Functional genomic screen and network analysis reveal novel modifiers of tauopathy dissociated from tau phosphorylation

Genes white, brown and rosy were identified as modifiers independent of the collections screened.

“We incorporated genes white, brown and rosy into the network, which we identified as modifiers independent of the collections we screened (61).”

• cites [61] Ambegaokar, 2010, Interaction between eye pigment genes and tau-induced neurodegeneration in Drosophila melanogaster, Genetics sourceSupported

In vivo fly models of tau toxicity using phosphorylation-resistant tau constructs show equivalent or even increased toxicity when compared with wild-type tau.

“in vivo fly models of tau toxicity using phosphorylation-resistant tau constructs show equivalent or even increased toxicity when compared with wild-type tau (41,42).”

• cites [41] Steinhilb, 2007, Tau phosphorylation sites work in concert to promote neurotoxicity in vivo, Mol. Biol. Cell sourcePartly supported

  The Results and Discussion report that fly tau constructs resistant to phosphorylation at individual sites, or at a selected group of five sites, caused toxicity similar to wild-type tau. They do not report increased toxicity for those constructs; the Results instead associate greater toxicity with a phosphomimetic construct and markedly reduced toxicity with mutation of all 14 SP/TP sites. Page numbers were not available in our copy. (LLM, conf=0.89)

  Experimental — accuracy not yet measured
• cites [42] Chatterjee, 2009, Dissociation of tau toxicity and phosphorylation: role of GSK-3βeta, MARK and Cdk5 in a Drosophila model, Hum. Mol. Genet. sourceSupported

Mature protein substrates of Tom70 were observed to be aggregate-prone in the absence of Tom70.

“Indeed, mature protein substrates of Tom70 were observed to be aggregate-prone in the absence of Tom70, suggesting a crucial role of Tom70 in preventing aggregation (69).”

• cites [69] Yamamoto, 2009, Roles of Tom70 in import of presequence-containing mitochondrial proteins, J. Biol. Chem. sourceSupported

No significant differences in phospho-tau levels relative to controls were observed for 12E8 and AT270 with modifiers from the EY screen.

“No significant differences in phospho-tau levels relative to controls were observed (Supplementary Material, Fig. S4).”

• cites [85] Seubert, 1995, Detection of phosphorylated Ser262 in fetal tau, adult tau, and paired helical filament tau, J. Biol. Chem. sourceCould not verify

  The immunoblot-analysis and 12E8 results passages describe tau phosphorylation and the 12E8 antibody, but do not report an EY modifier screen or a comparison with its controls. Searches for EY-screen modifiers and AT270 found no passage addressing the claimed absence of significant differences. Page numbers were not available in our copy. (LLM, conf=0.76)

  Experimental — accuracy not yet measured
• cites [86] Goedert, 1994, Epitope mapping of monoclonal antibodies to the paired helical filaments of Alzheimer's disease: identification of phosphorylation sites in tau protein, Biochem. J. sourceCould not verify

  The indexed Abstract characterizes AT270 and reports phosphorylation in fetal, adult, and paired-helical-filament tau. It does not address an EY screen, 12E8, or statistical comparisons of phospho-tau levels with controls; searches for those terms found no relevant passage. The cited paper therefore cannot verify the reported lack of a significant difference. (LLM, conf=0.76)

  Experimental — accuracy not yet measured

Tau phosphorylation at S202/T205 as detected by the AT8 antibody is commonly found in tauopathies.

“Tau phosphorylation at S202/T205 as detected by the AT8 antibody (80) is commonly found in tauopathies (38,81–84).”

• cites [80] Biernat, 1992, The switch of tau protein to an Alzheimer-like state includes the phosphorylation of two serine-proline motifs upstream of the microtubule binding region, EMBO J. sourcePartly supported

  The indexed Abstract identifies AT8 as a phosphorylation-dependent antibody whose epitope is around residue 200, supporting the AT8 identification cited as (80). It specifies phosphorylation of serines 199 and/or 202, however, not T205. The separate claim that this phosphorylation is common in tauopathies is attached to other citations, not (80). (LLM, conf=0.88)

  Experimental — accuracy not yet measured
• cites [38] Wada, 1998, Microtubule-stimulated phosphorylation of tau at Ser202 and Thr205 by Cdk5 decreases its microtubule nucleation activity, J. Biochem. sourceNot checked — no full text of the source
• cites [81] Wray, 2008, Direct analysis of tau from PSP brain identifies new phosphorylation sites and a major fragment of N-terminally cleaved tau containing four microtubule-binding repeats, J. Neurochem. sourceNot checked — no full text of the source
• cites [82] Ferrer, 2003, Phosphorylated protein kinases associated with neuronal and glial tau deposits in argyrophilic grain disease, Brain Pathol. sourcePartly supported

  The Abstract reports using a Ser202 phosphospecific antibody to examine tau in argyrophilic grain disease and finding hyperphosphorylated tau in all cases. It does not establish that S202/T205 phosphorylation is commonly found across tauopathies. The AT8 antibody identification is attached to a separate citation in the citing sentence. (LLM, conf=0.81)

  Experimental — accuracy not yet measured
• cites [83] Ikura, 1998, Levels of tau phosphorylation at different sites in Alzheimer disease brain, Neuroreport sourceNot checked — no full text of the source
• cites [84] Han, 2009, Familial FTDP-17 missense mutations inhibit microtubule assembly-promoting activity of tau by increasing phosphorylation at Ser202 in vitro, J. Biol. Chem. sourcePartly supported

  The Discussion (page unavailable) reports strong AT8 staining in Alzheimer’s disease and Ser202 phosphorylation recognized by AT8 in FTDP-17 brains. This supports AT8-detected Ser202 phosphorylation in those conditions, but the copy does not establish Thr205 phosphorylation or its prevalence across tauopathies. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

Expression of Aβ42 and TDP-43Q331K in the fly eye driven by GMR-GAL4 leads to eye phenotypes.

“Similar to tau and to polyglutamine proteins, expression of Aβ42 and TDP-43Q331K in the fly eye driven by GMR-GAL4 leads to eye phenotypes.”

• cites [89] Casas-Tinto, 2011, The ER stress factor XBP1s prevents amyloid-beta neurotoxicity, Hum. Mol. Genet. sourcePartly supported

  The “Generation of a new AD model in flies” section reports that Aβ42 expression with gmr-Gal4 produced small, disorganized eyes with necrotic spots. The cited paper does not report an eye phenotype for TDP-43Q331K, so it supports only the Aβ42 part of the claim. No page number is available in our copy. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

• AssumptionRests on an assumption: TDP-43Q331K is an amyotrophic lateral sclerosis-causing mutation.

S11A demonstrates severe toxicity when expressed in the eye, producing an even smaller and rougher eye than wild-type tau.

“Instead of alleviating toxicity, S11A demonstrates severe toxicity when expressed in the eye, producing an even smaller and rougher eye than wild-type tau (42).”

• cites [42] Chatterjee, 2009, Dissociation of tau toxicity and phosphorylation: role of GSK-3βeta, MARK and Cdk5 in a Drosophila model, Hum. Mol. Genet. sourcePartly supported

  The Results section describes S11A-expressing flies as having reduced, rough eyes with fused ommatidia and missing bristles. The Discussion says the S11A eye phenotype was, in several instances, as severe as that of wild-type tau; it does not support the claim that S11A produced an even smaller and rougher eye than wild-type tau. Page numbers were not available in our copy. (LLM, conf=0.89)

  Experimental — accuracy not yet measured

• AssumptionRests on an assumption: The sites mutated in S11A are commonly hyperphosphorylated in tauopathic tissue and are known to be phosphorylated by GSK-3β and CDK-5.

GSK-3β has not been identified as a kinase of TDP-43, even when specifically tested for TDP-43 phosphorylation.

“GSK-3β has not been identified as a kinase of TDP-43, even when specifically tested for TDP-43 phosphorylation (102)”

• cites [102] Hasegawa, 2008, Phosphorylated TDP-43 in frontotemporal lobar degeneration and amyotrophic lateral sclerosis, Ann. Neurol. sourcePartly supported

  The Methods describe an in vitro test of GSK3β on TDP-43. In the Results section, TDP-43 treated with GSK3β was negative with the study’s phosphorylation-specific antibodies. That supports a negative result for the epitopes tested, but not the broader assertion that GSK3β has not been identified as a TDP-43 kinase at any site. (LLM, conf=0.85)

  Experimental — accuracy not yet measured

• AssumptionRests on an assumption: TDP-43Q331K is an amyotrophic lateral sclerosis-causing mutation.

Inhibition or genetic reduction of GSK-3β ameliorates tau-related deficits.

“many investigators have shown that either inhibition or genetic reduction of GSK-3β ameliorates tau-related deficits (94–99).”

• cites [94] Mudher, 2004, GSK-3beta inhibition reverses axonal transport defects and behavioural phenotypes in Drosophila, Mol. Psychiatry sourceNot checked — no full text of the source
• cites [95] Noble, 2005, Inhibition of glycogen synthase kinase-3 by lithium correlates with reduced tauopathy and degeneration in vivo, Proc. Natl Acad. Sci. USA sourcePartly supported

  The Results and Discussion (page numbers unavailable) report that lithium reduced GSK-3β activity and that treatment with GSK-3 inhibitors was associated with less aggregated tau and degeneration in mice. The paper does not report genetic reduction of GSK-3β, so it supports the inhibition part of the claim but not the genetic-reduction part. (LLM, conf=0.87)

  Experimental — accuracy not yet measured
• cites [96] Miyasaka, 2005, Progressive neurodegeneration in C. elegans model of tauopathy, Neurobiol. Dis. sourceNot checked — no full text of the source
• cites [97] Kraemer, 2006, Molecular pathways that influence human tau-induced pathology in Caenorhabditis elegans, Hum. Mol. Genet. sourceNot checked — no full text of the source
• cites [98] Blard, 2007, Cytoskeleton proteins are modulators of mutant tau-induced neurodegeneration in Drosophila, Hum. Mol. Genet. sourcePartly supported

  The References (ref. 13) list a study reporting that GSK-3β inhibition reverses axonal-transport defects and behavioural phenotypes in Drosophila, supporting the inhibition part of the claim. But this paper’s Discussion (p. 565–566) says its screen did not identify GSK-3β modifiers; it does not report that genetic reduction of GSK-3β ameliorates tau-related deficits. (LLM, conf=0.78)

  Experimental — accuracy not yet measured
• cites [99] Folwell, 2009, Abeta exacerbates the neuronal dysfunction caused by human tau expression in a Drosophila model of Alzheimer's disease, Exp. Neurol. sourceNot checked — no full text of the source

When either 5 or 11 putative GSK-3β phosphorylation sites were mutated to alanine, tau toxicity either comparable to or more robust than the toxicity induced by wild-type tau was still observed.

“when either 5 (41) or 11 (42) putative GSK-3β phosphorylation sites were mutated to alanine, tau toxicity either comparable to or more robust than the toxicity induced by wild-type tau was still observed.”

• cites [41] Steinhilb, 2007, Tau phosphorylation sites work in concert to promote neurotoxicity in vivo, Mol. Biol. Cell sourceSupported
• cites [42] Chatterjee, 2009, Dissociation of tau toxicity and phosphorylation: role of GSK-3βeta, MARK and Cdk5 in a Drosophila model, Hum. Mol. Genet. sourceSupported

GSK-3β phosphorylation of tau was independent of phosphorylation by PAR-1.

“However, our laboratory observed that GSK-3β phosphorylation of tau was independent of phosphorylation by PAR-1 (42).”

• cites [42] Chatterjee, 2009, Dissociation of tau toxicity and phosphorylation: role of GSK-3βeta, MARK and Cdk5 in a Drosophila model, Hum. Mol. Genet. sourceSupported

MARK-2 overexpression in primary neurons reduces tau-induced deficits by alleviating organelle and vesicle transport blockade.

“Furthermore, MARK-2 overexpression in primary neurons reduces tau-induced deficits by alleviating organelle and vesicle transport blockade (40,126).”

• cites [40] Thies, 2007, Missorting of tau in neurons causes degeneration of synapses that can be rescued by the kinase MARK2/Par-1, J. Neurosci. sourceSupported
• cites [126] Schneider, 1999, Phosphorylation that detaches tau protein from microtubules (Ser262, Ser214) also protects it against aggregation into Alzheimer paired helical filaments, Biochemistry sourceNot checked — no full text of the source

LOF of Nrg causes significant reduction in microtubules at synaptic terminals.

“LOF of Nrg causes significant reduction in microtubules at synaptic terminals (140,141)”

• cites [140] Godenschwege, 2006, A conserved role for Drosophila Neuroglian and human L1-CAM in central-synapse formation, Curr. Biol. sourceNot checked — no full text of the source
• cites [141] Shimada, 2008, Shootin1 interacts with actin retrograde flow and L1-CAM to promote axon outgrowth, J. Cell Biol. sourceCould not verify

  The Results sections provided (page numbers unavailable) examine shootin1 and L1-dependent axon outgrowth in hippocampal neurons, not Nrg loss of function at synaptic terminals. Searches for Nrg/neuroglian and for reduced microtubules at synaptic terminals found no passage addressing the claim. (LLM, conf=0.76)

  Experimental — accuracy not yet measured

Mutations in the pigment-associated genes white, brown and rosy enhance tau toxicity.

“Furthermore, we previously identified mutations in the pigment-associated genes white, brown and rosy that enhance tau toxicity (61).”

• cites [61] Ambegaokar, 2010, Interaction between eye pigment genes and tau-induced neurodegeneration in Drosophila melanogaster, Genetics sourcePartly supported

  The Abstract says null mutations in white and brown enhance the rough-eye phenotype in the Drosophila tauopathy model. It says the opposite for rosy: adding rosy mutations suppresses those effects, rather than enhancing tau toxicity. (LLM, conf=0.90)

  Experimental — accuracy not yet measured

Genetic manipulation of PSA expression in our model was previously shown to strongly modify tau toxicity.

“Whether by cleavage or by autophagy, genetic manipulation of PSA expression in our model was previously shown in a candidate genetic approach to strongly modify tau toxicity (48).”

• cites [48] Karsten, 2006, A genomic screen for modifiers of tauopathy identifies puromycin-sensitive aminopeptidase as an inhibitor of tau-induced neurodegeneration, Neuron sourceSupported

Here we report novel modifiers distinct from those identified in two recent reports that also screened for genetic modifiers of tau-induced neurodegeneration in Drosophila.

“Here we report novel modifiers distinct from those identified in two recent reports that also screened for genetic modifiers of tau-induced neurodegeneration in Drosophila (52,98).”

• cites [52] Shulman, 2003, Genetic modifiers of tauopathy in Drosophila, Genetics sourceNot checked — no full text of the source
• cites [98] Blard, 2007, Cytoskeleton proteins are modulators of mutant tau-induced neurodegeneration in Drosophila, Hum. Mol. Genet. sourceSupported

A direct fusion construct of the human full-length (2N/4R) tau cDNA to the eye-specific glass promoter induces a rough eye phenotype (gl-tau line).

“A direct fusion construct of the human full-length (2N/4R) tau cDNA to the eye-specific glass promoter induces a rough eye phenotype (gl-tau line), as previously described in Jackson et al. (47).”

• cites Jackson et al. [47] Jackson, 2002, Human wild-type tau interacts with wingless pathway components and produces neurofibrillary pathology in Drosophila, Neuron sourceSupported

The w+ marker gene in the P elements used in the P lethal and EY collections modifies the tau phenotype in a w+ dose-dependent manner.

“the w+ marker gene in the P elements used in the P lethal and EY collections modified the tau phenotype in a w+ dose-dependent manner (61)”

• cites [61] Ambegaokar, 2010, Interaction between eye pigment genes and tau-induced neurodegeneration in Drosophila melanogaster, Genetics sourcePartly supported

  Our copy (section labeled Abstract; no page available) reports that P-element insertions affected the tau rough-eye phenotype and that increasing copies of mini-white suppressed white mutation-induced toxicity in a dose-dependent manner. It does not identify the P lethal or EY collections, so the claim's collection-specific attribution is not established. (LLM, conf=0.83)

  Experimental — accuracy not yet measured

The data presented here provide further evidence that therapeutic approaches alternative to mitigating tau phosphorylation (such as improved microtubule stability) may be productive.

“the data presented here provide further evidence that such approaches may be productive”

• cites [354] Zhang, 2005, Microtubule-binding drugs offset tau sequestration by stabilizing microtubules and reversing fast axonal transport deficits in a tauopathy model, Proc. Natl Acad. Sci. USA sourceSupported
• cites [355] Brunden, 2010, Epothilone D improves microtubule density, axonal integrity, and cognition in a transgenic mouse model of tauopathy, J. Neurosci. sourceSupported

Diets with increased cholesterol increase tau phosphorylation in wild-type and human tau transgenic mammals.

“Reports in both wild-type and in human tau transgenic mammals indicate that diets with increased cholesterol do indeed increase tau phosphorylation (265–267).”

• cites [265] Ghribi, 2008, Potential mechanisms linking cholesterol to Alzheimer's disease-like pathology in rabbit brain, hippocampal organotypic slices, and skeletal muscle, J. Alz. Dis. sourcePartly supported

  The “Cholesterol and Tau Phosphorylation” section reports that a cholesterol-enriched diet caused hyperphosphorylated tau accumulation in rabbits. It discusses tau-transgenic mice separately, but does not report that a cholesterol-enriched diet increased tau phosphorylation in those animals. Page numbers are not available in our copy. (LLM, conf=0.88)

  Experimental — accuracy not yet measured
• cites [266] Harris, 2010, Cholesterol in Alzheimer's disease and other amyloidogenic disorders, Subcell. Biochem. sourceNot checked — no full text of the source
• cites [267] Glöckner, 2011, Dietary cholesterol and its effect on tau protein: a study in apolipoprotein E-deficient and P301L human tau mice, J. Neuropathol. Exp. Neurol. sourceNot checked — no full text of the source

No modifier stock showed an intrinsic effect on eye morphology when crossed to w1118.

“No modifier stock showed an intrinsic effect on eye morphology when crossed to w1118 in order to remove any effects of balancer chromosomes”

Modifiers showed poor correlation with tau phosphorylation using the AT8, 12E8 and AT270 epitopes.

“Modifiers showed poor correlation with tau phosphorylation (using the AT8, 12E8 and AT270 epitopes)”

Reduced GSK-3β dosage is a common suppressor of Aβ42 and TDP-43 toxicity.

“reduced GSK-3β dosage is also a common suppressor of Aβ42 and TDP-43 toxicity.”

The identified modifiers include the kinases shaggy/GSK-3beta, par-1/MARK, CamKI and Mekk1.

“including the kinases shaggy/GSK-3beta, par-1/MARK, CamKI and Mekk1.”

A total of 23 modifiers-11 suppressors and 12 enhancers-were identified from the P lethal screen of 920 stocks.

“A total of 23 modifiers—11 suppressors and 12 enhancers—were identified from the P lethal screen of 920 stocks”

Genes related to autophagy, the cell cycle, RNA-associated proteins and chromatin-binding proteins constitute a large percentage of identified modifiers.

“Genes related to autophagy, the cell cycle, RNA-associated proteins and chromatin-binding proteins constitute a large percentage of identified modifiers.”

NC2α and SdhB showed moderate suppression of the Q108 phenotype.

“However, NC2α and SdhB did show moderate suppression of the Q108 phenotype.”

Network analysis uncovered several other genes highly associated with the functional modifiers, including genes related to the PI3K, Notch, BMP/TGF-β and Hedgehog pathways, and nuclear trafficking.

“Network analysis uncovered several other genes highly associated with the functional modifiers, including genes related to the PI3K, Notch, BMP/TGF-β and Hedgehog pathways, and nuclear trafficking.”

Tau acts synergistically with Mekk1 and p38 to down-regulate extracellular regulated kinase (ERK) activity.

“Tau acts synergistically with Mekk1 and p38 to down-regulate extracellular regulated kinase activity”

No modifiers from the P lethal screen showed any appreciable suppression of the hid phenotype.

“No modifiers from the P lethal screen showed any appreciable suppression of the hid phenotype (Fig. 2).”

Other functional categories identified among modifiers include mitochondrial proteins, lipid trafficking, Golgi proteins, kinesins and dynein and the Hsp70/Hsp90-organizing protein (Hop).

“Other functional categories identified include mitochondrial proteins, lipid trafficking, Golgi proteins, kinesins and dynein and the Hsp70/Hsp90-organizing protein (Hop).”

Tested suppressors of wild-type tau were equally effective in suppressing toxicity of a phosphorylation-resistant S11A tau construct.

“tested suppressors of wild-type tau were equally effective in suppressing toxicity of a phosphorylation-resistant S11A tau construct”

Out of a total of 40 modifier genes, 17 do not meet the more rigorous criteria as applied to the other modifiers.

“Thus, out of a total of 40 modifier genes, 17 do not meet the more rigorous criteria as applied to the other modifiers”

The down-regulation of ERK activity by tau with Mekk1 and p38 corresponds to a decrease in AT8 immunoreactivity (pS202/T205).

“with a corresponding decrease in AT8 immunoreactivity (pS202/T205)”

Activity of GSK-3β is strongly upregulated due to TDP-43 expression.

“Activity of GSK-3β is strongly upregulated due to TDP-43 expression”

The functional genetic screen identified 37 additional modifier genes of tau-induced neurotoxicity from approximately 1900 genes screened.

“here, we report 37 additional genes identified from ∼1900 genes screened”

• Also stated in: § INTRODUCTION · plain

  “In total, 37 genes of the ∼1900 lines screened were uncovered as strong modifiers of tau toxicity.”

Tom34 and csul showed very strong effects on the gl-tau phenotype.

“Tom34, identified in the Mitochondrial gene cluster, and csul, identified in the RNA Trafficking cluster, showed very strong effects on the gl-tau phenotype (Fig. 5B).”

Most other RNA-associated genes uncovered in the screen did not also modify the Q108 phenotype.

“Given this, however, it is peculiar that most other RNA-associated genes uncovered in the screen did not also modify Q108 phenotype.”

No consistent pattern of S202/T205 phosphorylation can be attributed to a suppressive or enhancing effect of tau-induced toxicity.

“Thus, no consistent pattern of S202/T205 phosphorylation can be attributed to a suppressive or enhancing effect of tau-induced toxicity.”

• Also stated in: § Phosphorylation of tau does not correlate with enhancement or suppression of tau toxicity · plain

  “however, no pattern of phosphorylation correlated with enhancement or suppression of the tau phenotype.”

No change in GSK-3β activity was observed with Mekk1 overexpression.

“No change in GSK-3β activity was observed with Mekk1 overexpression.”

• Also stated in: § Tau demonstrates synergy with Mekk1 and p38 to decrease ERK activity · plain

  “No significant difference was observed for GSK-3β activity (phospho-GSK-3β-Ser9).”

In total, four kinases were identified in the functional screen-sgg/GSK-3β, par-1/MARK1, CamKI and Mekk1.

“In total, four kinases were identified in the functional screen—sgg/GSK-3β, par-1/MARK1, CamKI and Mekk1.”

When tau was co-expressed with Mekk1, a profound reduction (~60%) in phospho-ERK was observed.

“However, when tau was co-expressed with Mekk1, a profound reduction (∼60%) in phospho-ERK was observed (Fig. 7A).”

• Also stated in: § Tau demonstrates synergy with Mekk1 and p38 to decrease ERK activity · boosted

  “tau and Mekk1 co-overexpression strongly reduced phospho-ERK levels (second lane).”

Modifiers did not show a statistically significant difference in total tau levels relative to controls.

“Modifiers did not show a statistically significant difference in total tau levels relative to controls (Supplementary Material, Fig. S3), indicating that altered toxicity was not due to changing tau expression.”

• Also stated in: § Phosphorylation of tau does not correlate with enhancement or suppression of tau toxicity · plain

  “Modifiers did not significantly alter total tau expression.”

The increase in p38 activity was comparable to overexpression of Mekk1 alone.

“This increase in p38 activity was comparable to overexpression of Mekk1 alone (GMR-GAL4/+;Mekk1EY/+), indicating that p38 activity is not tau-dependent.”

No significant differences in AT8 levels were found for nearly all modifiers from the P lethal screen compared with controls.

“Unexpectedly, no significant differences in AT8 levels were found for nearly all modifiers from the P lethal screen when compared with controls.”

sgg and par-1 mutations did not show any significant effect on AT8 levels in trans to gl-tau.

“However, sgg and par-1 mutations did not show any significant effect on AT8 levels in trans to gl-tau, whereas CamKI and Mekk1, both enhancers, showed significant decreases in AT8 levels.”

Approximately half (18 of 40) of the modifiers showed no significant differences in phospho-tau when compared with control.

“Approximately half (18 of 40) of the modifiers showed no significant differences in phospho-tau when compared with control.”

Overexpression of Mekk1 alone did not produce any difference in phospho-ERK levels when compared with gl-tau-only flies.

“Overexpression of Mekk1 alone (GMR-GAL4/+;Mekk1EY/+) did not produce any difference in phospho-ERK levels when compared with gl-tau-only flies (GMR-GAL4/+;gl-tau/+).”

• Also stated in: § Tau demonstrates synergy with Mekk1 and p38 to decrease ERK activity · plain

  “ERK activity (phospho-ERK) was equivalent for tau expression alone (first lane) and Mekk1 expression alone (third lane)”

Suppressor CG31630 did not show a change in phosphorylation.

“Suppressor CG31630 did not show a change in phosphorylation, and the enhancer smooth was the only gene from either screen that had a significant increase in its AT8 level.”

Nearly all modifiers from the EY screen-suppressors and enhancers alike-showed robust decreases in phosphorylation.

“On the other hand, nearly all modifiers from the EY screen—suppressors and enhancers alike—showed robust decreases in phosphorylation.”

armi modified tau toxicity, enhancing toxicity with both loss-of-function and gain-of-function approaches.

“We also confirmed that the RNA Catabolism gene, armi, modified tau toxicity, enhancing toxicity with both LOF and GOF approaches.”

Alleles tested for Upf1 and Tom20 did not show significant changes in the gl-tau phenotype.

“Alleles tested for RNA Catabolism gene, Upf1, and the mitochondrial gene, Tom20, did not show significant changes in the gl-tau phenotype (data not shown).”

Immunoblots showed modest but statistically significant increases in activated p38 in GMR-GAL4/+;Mekk1EY/gl-tau fly heads compared with GMR-GAL4/+;gl-tau/+ flies.

“Using the GMR-GAL4 driver with the Mekk1 EY line, immunoblots showed modest but statistically significant increases in activated p38 in GMR-GAL4/+;Mekk1EY/gl-tau fly heads when compared with GMR-GAL4/+;gl-tau/+ flies (Fig. 7A).”

• Also stated in: § Tau demonstrates synergy with Mekk1 and p38 to decrease ERK activity · plain

  “Mekk1 overexpression induced a modest significant increase in p38 activity (phospho-p38) independent of human tau expression.”

Enhancer smooth was the only gene from either screen that had a significant increase in its AT8 level.

“Suppressor CG31630 did not show a change in phosphorylation, and the enhancer smooth was the only gene from either screen that had a significant increase in its AT8 level.”

TDP-43Q331K expression strongly induces GSK-3β activity, as indicated by reduced pGSK-3β [Ser9].

“A very strong increase in GSK-3β activity induced by TDP-43Q331K was observed, as indicated by reduced levels of pGSK-3β [Ser9] (Fig. 8D).”

• AssumptionRests on an assumption: TDP-43Q331K is an amyotrophic lateral sclerosis-causing mutation.

sgg strongly suppresses TDP-43Q331K toxicity.

“we also assayed sgg and ksr against TDP-43Q331K toxicity and found strong suppression with sgg.”

• AssumptionRests on an assumption: TDP-43Q331K is an amyotrophic lateral sclerosis-causing mutation.

The modifiers did not have anti-apoptotic effects.

“did not have anti-apoptotic effects (as assessed by their ability to suppress the proapoptotic effects of hid; see Fig. 4)”

Alleles of Dlic2 suppressed S11A toxicity.

“Alleles of Dynein light chain 2 (Dlic2) suppressed S11A toxicity”

• AssumptionRests on an assumption: The sites mutated in S11A are commonly hyperphosphorylated in tauopathic tissue and are known to be phosphorylated by GSK-3β and CDK-5.

No enhancer showed any effect with S2A.

“Surprisingly, no enhancer showed any effect with S2A”

ksr mutants showed a strong and statistically significant increase in inactivated GSK-3β.

“However, surprisingly, we observed a strong and statistically significant increase in inactivated GSK-3β in ksr mutants.”

In total, 37 hits were identified from ∼1900 lines screened.

“In total, 37 hits were identified from ∼1900 lines screened (Figs 1 and 3).”

TauS2A shows no toxicity in the eye.

“the TauS2A (or S2A) isoform has only two serines mutated to alanines (S262, S356), yet shows no toxicity in the eye.”

No consistent pattern between suppressors or enhancers was observed for GSK-3β phosphorylation state across all modifiers.

“Given this result, we assayed all the modifiers for GSK-3β phosphorylation state, as an indicator of GSK-3β activity, to determine whether GSK-3β was a common final pathway for toxicity, but no consistent pattern between suppressors or enhancers was observed (data not shown).”

ksr partially suppressed the TDP-43Q331K phenotype.

“from which we conclude that ksr partially suppressed the TDP-43Q331K phenotype.”

• AssumptionRests on an assumption: TDP-43Q331K is an amyotrophic lateral sclerosis-causing mutation.

The modifiers did not have independent effects on eye morphology.

“they (a) did not have independent effects on eye morphology”

A sgg/GSK-3β LOF allele suppresses the phosphorylation-resistant S11A construct.

“a sgg/GSK-3β LOF allele still showed suppression of the phosphorylation-resistant S11A construct”

• AssumptionRests on an assumption: The sites mutated in S11A are commonly hyperphosphorylated in tauopathic tissue and are known to be phosphorylated by GSK-3β and CDK-5.

Of the suppressors tested against Aβ42, only sgg showed robust suppression of the phenotype.

“Of these suppressors, only sgg showed a robust suppression of the phenotype, with increased size and volume of the eye”

All suppressors tested were able to suppress S11A toxicity.

“All suppressors tested were able to suppress S11A toxicity.”

• AssumptionRests on an assumption: The sites mutated in S11A are commonly hyperphosphorylated in tauopathic tissue and are known to be phosphorylated by GSK-3β and CDK-5.

Reductions in sgg and par-1 gene dosage have opposite effects on the tau phenotype.

“In the data presented here, reductions in sgg and par-1 gene dosage have opposite effects on the tau phenotype”

Our computational approach found the Insulin/PI3K and Hedgehog/Smoothened pathways to be highly associated with the modifiers identified in the screen.

“Our computational approach found the Insulin/PI3K and Hedgehog/Smoothened pathways to be highly associated with the modifiers identified in the screen.”

Our screen implicates the ERK/MAPK and p38/MAPK pathways in tauopathy.

“In addition to the PI3K and Wnt signaling pathways discussed above, our screen implicates other key pathways in tauopathy, including the ERK/MAPK and p38/MAPK pathways.”

There were no significant differences between suppressors and enhancers at either 12E8 or AT270 epitopes.

“There were no significant differences between suppressors and enhancers at either 12E8 or AT270 epitopes (Supplementary Material, Fig. S4).”

Loss-of-function of Atg6 increases tau toxicity.

“We uncovered an LOF allele of Autophagy-specific gene 6 (Atg6), the Drosophila homolog of mammalian Beclin-1, that increases tau toxicity, further implicating autophagy as a protective process.”

white homozygotes show a decrease in phospho-S6K compared with white heterozygotes.

“we observe a decrease in phospho-S6K in white homozygotes when compared with white hetereozygotes, suggesting that target of rapamycin-regulated autophagy is activated dose-dependently by white mutations (189).”

• cites [189] Ambegaokar, 2011, Double vision: pigment genes do more than just color, Fly sourceNot checked — no full text of the source

LOF alleles of ksr and Neuroglian (Nrg) suppress tau toxicity.

“LOF alleles of ksr and Neuroglian (Nrg), both of which promote ERK signaling (133–136), suppress tau toxicity”

Loss-of-function of Hop enhances tau toxicity.

“In our screen, LOF of Hop enhances tau toxicity, providing further evidence for the role of chaperones in tauopathy.”

We could not observe a consistent pattern between suppressors or enhancers when assaying GSK-3β activity among all other modifiers.

“However, when we assayed for GSK-3β activity among all other modifiers, we could not observe a consistent pattern between suppressors or enhancers (data not shown).”

The screen identified Vha14, a subunit of the V1 head group of the vacuolar ATPase complex.

“Our screen also identified Vha14, a subunit of the V1 head group of the vacuolar ATPase (v-ATPase) complex that is required for lysosomal acidification (183).”

• cites [183] Dow, 1999, The multifunctional Drosophila melanogaster V-ATPase is encoded by a multigene family, J. Bioenerg. Biomembr. sourceNot checked — no full text of the source

The computational network independently identified the protease PSA as highly associated with tau modifiers.

“The computational network independently identified the protease PSA as highly associated with tau modifiers.”

Tango5BG02353 produced an enhanced rough eye phenotype similar to that observed with stock No. 10151.

“Tango5BG02353 produced an enhanced rough eye phenotype similar to that observed with stock No. 10151”

The effects of GSK-3β activity are most pronounced under conditions of low ERK activity.

“but its effects are most pronounced under conditions of low ERK activity”

Our computational network identified Npc1 as highly associated with the modifier network.

“Our computational network identified Npc1, the Drosophila homolog of NPC1, as highly associated with the modifier network, further validating the network to identify relevant tauopathic genes.”

Reduction in dynein suppresses tau toxicity.

“Unexpected is the suppression of tau toxicity due to reduction in dynein.”

40 genetic modifiers were identified as strong modifiers of tau toxicity.

“In sum, 40 genetic modifiers were identified as strong modifiers of tau toxicity (Table 1); of these, sgg/GSK-3β and par-1/MARK-2 are known tau kinases, validating the design of the screen to identify modifiers of tau or tau toxicity.”

EY stock number 22422, which only affects milton, had no effect on the tau phenotype.

“EY stock number 22422, which only affects milton, was screened and had no effect on the tau phenotype”

bancalkG02524 and blG13574 showed enhanced toxicity often with necrotic plaques.

“bancalkG02524 and blG13574 showed enhanced toxicity often with necrotic plaques”

In nearly all RNA-associated modifiers identified in this screen, a loss-of-function led to increased toxicity.

“In nearly all RNA-associated modifiers identified in this screen, an LOF led to increased toxicity; this may be due to a reduced number of proteins able to sequester RNA away from the tau protein.”

A second allele of frc (frc0073) confirmed its suppressive effects on tau toxicity.

“A second allele of frc (frc0073) confirmed its suppressive effects on tau toxicity; however, none of the fng alleles tested (fngrG554, fng13, fngM69, fngL73, fng52) showed any effect on the tau phenotype, suggesting that altered Notch signaling does not underlie frc suppression of tau toxicity.”

Mutant TDP-43Q331K strongly increases GSK-3β activity.

“we report that mutant TDP-43Q331K strongly increases GSK-3β activity”

We demonstrate in vivo differential effects of kinesins (cana and Klp61F) and dynein (Dlic2) with tau-induced neurotoxicity.

“We demonstrate in vivo differential effects of kinesins (cana and Klp61F) and dynein (Dlic2) with tau-induced neurotoxicity.”

ksr can signal through the MAPK/ERK pathway.

“as well as through the MAPK/ERK pathway”

Reduction in smallminded (smid) gene dosage showed a dramatic suppression of tau-induced toxicity.

“Reduction in smallminded (smid) gene dosage showed a dramatic suppression of tau-induced toxicity.”

Suppressors of wild-type tau are equally able to suppress the phosphorylation-resistant but more toxic S11A tau isoform.

“suppressors of wild-type tau are equally able to suppress the phosphorylation-resistant but more toxic S11A tau isoform”

Tau phosphorylation at S202/T205 (AT8 epitope), S262/S356 (12E8 epitope) or T181 (AT270 epitope) did not correlate with toxicity.

“Tau phosphorylation at S202/T205 (AT8 epitope), S262/S356 (12E8 epitope) or T181 (AT270 epitope) did not correlate with toxicity, arguing against tau phosphorylation as”

Reducing GSK-3β (sgg) expression strongly suppresses TDP-43 and Aβ42 toxicity.

“reducing GSK-3β (sgg) expression strongly suppresses TDP-43 and Aβ42 toxicity”

GSK-3β activity highly correlates with toxicity.

“We observe that GSK-3β activity highly correlates with toxicity”

Hop enhanced toxicity.

“Hop but not U2af38 enhanced toxicity”

ksr can signal through the insulin/GSK-3β pathway.

“we demonstrate that ksr can signal through the insulin/GSK-3β pathway”

The non-toxic S2A tau isoform could not be induced to show toxicity with genetic enhancers.

“the non-toxic S2A tau isoform could not be induced to show toxicity with genetic enhancers”

Allele rig05056 had little effect on the tau phenotype.

“Allele rig05056 had little effect on the tau phenotype”

The common background mutation white (w) is itself a modifier of tau-induced neurotoxicity.

“it was discovered that the common background mutation white (w) was itself a modifier of tau-induced neurotoxicity”

A surprising number of modifiers identified from the screen play a role in regulating the cell cycle or chromatin binding.

“A surprising number of modifiers identified from the screen play a role in regulating the cell cycle or chromatin binding, lending further credence to the mitotic failure/cell-cycle re-entry hypothesis of neurodegeneration.”

The gene Psn was highly associated with tau modifiers in our computational network.

“The gene Psn, which encodes the single fly presenilin, was highly associated with tau modifiers in our computational network.”

U2af38 did not enhance toxicity.

“Hop but not U2af38 enhanced toxicity”

None of the fng alleles tested showed any effect on the tau phenotype.

“A second allele of frc (frc0073) confirmed its suppressive effects on tau toxicity; however, none of the fng alleles tested (fngrG554, fng13, fngM69, fngL73, fng52) showed any effect on the tau phenotype, suggesting that altered Notch signaling does not underlie frc suppression of tau toxicity.”

These findings suggest therapeutic targets other than mitigation of tau phosphorylation.

“These findings suggest therapeutic targets other than mitigation of tau phosphorylation.”

In most cases, at least two alleles were tested and confirmed to have the same effect on tau toxicity.

“In most of the cases, at least two alleles were tested and confirmed to have the same effect on tau toxicity, either through an LOF or a GOF allele.”

Important modifiers might not have been detected by our functional screen design.

“Thus, important modifiers might not have been detected by our functional screen design.”

The screen described here differs from previously reported screens in that the tau toxicity is induced by wild-type (non-mutant) tau.

“(ii) the tau toxicity is induced by wild-type (non-mutant) tau.”

Changes in tau phosphorylation state are not required to suppress or enhance tau toxicity.

“demonstrating that changes in tau phosphorylation state are not required to suppress or enhance its toxicity.”

Tom34 and Tom70 function more as chaperone proteins.

“This suggests that Tom34 and Tom70 function more as chaperone proteins which would help to explain why increased expression of Tom34 suppresses tau toxicity.”

Other factors that regulate or modify wild-type tau function must be involved in most tauopathies.

“suggesting that other factors that regulate or modify wild-type tau function must be involved.”

• AssumptionRests on an assumption: Most tauopathies are idiopathic and lack causative mutations in MAPT.

Our screen was not saturating: less than 20% of the approximately 12,000 fly genes were screened.

“Although the collection of genes screened was large and spanned the genome, our screen was not saturating: less than 20% of the ∼12 000 fly genes were screened.”

Tau can participate in signaling pathways to regulate its own kinases.

“suggesting that tau can participate in signaling pathways to regulate its own kinases.”

Pedigree studies in hereditary FTDP-17 identified mutations in the MAPT gene, demonstrating that dysregulated or dysfunctional tau can be a causative factor in inducing neurodegeneration.

“Pedigree studies in hereditary cases of frontotemporal dementia with parkinsonism linked to chromosome 17 (FTDP-17) (3,4) identified mutations in the MAPT gene, demonstrating that dysregulated or dysfunctional tau can be a causative factor in inducing neurodegeneration.”

• cites [3] Hutton, 1998, Association of missense and 5′-splice-site mutations in tau with the inherited dementia FTDP-17, Nature sourceNot checked — no full text of the source
• cites [4] Poorkaj, 1998, Tau is a candidate gene for chromosome 17 frontotemporal dementia, Ann. Neurol. sourceNot checked — no full text of the source

l(3)L6332's modifying effect is not attributable to any effect on tau expression.

“thus, its modifying effect is not attributable to any effect on tau expression.”

Mekk1/p38 and tau have a synergistic effect in down-regulating ERK activity.

“These data demonstrate a synergistic effect between Mekk1/p38 and tau in down-regulating ERK activity and suggest that tau has signaling properties to regulate the kinases or phosphatases that in turn regulate tau itself.”

Altered toxicity was not due to changing tau expression.

“indicating that altered toxicity was not due to changing tau expression.”

Tau has signaling properties to regulate the kinases or phosphatases that in turn regulate tau itself.

“These data demonstrate a synergistic effect between Mekk1/p38 and tau in down-regulating ERK activity and suggest that tau has signaling properties to regulate the kinases or phosphatases that in turn regulate tau itself.”

p38 activity is not tau-dependent.

“This increase in p38 activity was comparable to overexpression of Mekk1 alone (GMR-GAL4/+;Mekk1EY/+), indicating that p38 activity is not tau-dependent.”

The ability to empirically validate modification of toxicity of at least two genes identified by network association, from two different gene categories, suggests the potential of this network to identify future modifiers.

“However, the ability to empirically validate modification of toxicity of at least two genes identified by network association, from two different gene categories, suggests the potential of this network to identify future modifiers.”

Modifying the severity of tau-induced toxicity does not require altering the phosphorylation state of tau.

“Taken together, these results show that modifying the severity of tau-induced toxicity does not require altering the phosphorylation state of tau.”

• Also stated in: § Phosphorylation of tau does not correlate with enhancement or suppression of tau toxicity · plain

  “Modifying tau toxicity does not require altering tau phosphorylation state.”

The results validate the specificity of the enhancers in acting on the toxic effects of tau and not simply on the effect of misexpression of human tau protein.

“These results also further validate the specificity of the enhancers in acting on the toxic effects of tau and not simply on the effect of misexpression of human tau protein.”

The two serines mutated to alanines in S2A effectively make the tau protein inert in effecting toxicity, even in conditions promoting degeneration.

“We conclude from these results that these two select serines mutated to alanines effectively make the tau protein inert in effecting toxicity, even in conditions promoting degeneration.”

The role of GSK-3β in tau toxicity extends beyond direct tau phosphorylation.

“indicating that the role of GSK-3β in tau toxicity extends beyond direct tau phosphorylation.”

• AssumptionRests on an assumption: The sites mutated in S11A are commonly hyperphosphorylated in tauopathic tissue and are known to be phosphorylated by GSK-3β and CDK-5.

The effects of GSK-3β in TDP-43 toxicity observed here are likely TDP-43 phosphorylation-independent.

“it is likely that the effects of GSK-3β in TDP-43 toxicity observed here also are TDP-43 phosphorylation-independent.”

• AssumptionRests on an assumption: TDP-43Q331K is an amyotrophic lateral sclerosis-causing mutation.

GSK-3β phosphorylation state correlates with toxicity in reduced ERK activity conditions.

“GSK-3β phosphorylation state correlates with toxicity in reduced ERK activity conditions”

Microtubule-binding protein dynamics play a significant role in S11A and wild-type tau toxicity.

“lending further credence to the hypothesis that microtubule-binding protein dynamics play a significant role in S11A and wild-type tau toxicity.”

• AssumptionRests on an assumption: The sites mutated in S11A are commonly hyperphosphorylated in tauopathic tissue and are known to be phosphorylated by GSK-3β and CDK-5.

The approach can identify bona fide tau modifiers.

“providing a proof of principle that our approach can identify bona fide tau modifiers.”

The modifiers showed a high degree of specificity for tau-induced toxicity.

“These modifiers showed a high degree of specificity for tau-induced toxicity”

Robust expression of S2A with the enhancer alleles was confirmed by western blot.

“robust expression of S2A with the enhancer alleles was confirmed by western blot (Fig. 8B).”

The lack of toxicity of the S2A mutant tau construct underscores the role phosphorylation can play in tau toxicity.

“This result underscores the role phosphorylation can play in tau toxicity.”

There is additional evidence of shared regulatory pathways between GSK-3β and PAR-1.

“There is additional evidence of shared regulatory pathways between GSK-3β and PAR-1.”

A model of GSK-3β and PAR-1 antagonism, in which kinases that inactivate GSK-3β also enhance PAR-1 activity.

“Together, these data suggest a model of GSK-3β and PAR-1 antagonism, in which kinases that inactivate GSK-3β also enhance PAR-1 activity.”

Phosphorylation is not the only determinant of tau toxicity.

“the lack of correlation we observed between tau modifiers and their effects on phosphorylation suggest that this post-translational modification is not the only determinant of tau toxicity.”

It is the functional consequences of phosphorylation that determine toxicity and not simply increased levels of phosphorylation.

“the difference between lack of toxicity with the S2A mutant and the severe toxicity observed with S11A highlight that it is the functional consequences of phosphorylation that determine toxicity and not simply increased levels of phosphorylation.”

Alteration of tau phosphorylation state is not required to modify tau toxicity.

“The results presented here support a plethora of data that show phosphorylation can affect tau toxicity but demonstrate that alteration of tau phosphorylation state is not required to modify tau toxicity.”

GSK-3β may regulate tau toxicity through its role in metabolic signaling and activation of the FoxO class of transcription factors.

“thus, GSK-3β may regulate tau toxicity through its role in metabolic signaling and activation of the FoxO class of transcription factors (113,114).”

• cites [113] Erol, 2009, Unraveling the molecular mechanisms behind the metabolic basis of sporadic Alzheimer's disease, J. Alz. Dis. sourceNot checked — no full text of the source
• cites [114] Manolopoulos, 2010, Linking Alzheimer's disease to insulin resistance: the FoxO response to oxidative stress, Mol. Psychiatry sourceNot checked — no full text of the source

The finding that increased par-1 expression suppressed mutant tau-induced toxicity agrees with the results from the P lethal screen reported here.

“the latter finding agrees with the results from the P lethal screen reported here.”

Phosphorylation is an important regulatory feature of tau function.

“The presence of hyperphosphorylated tau in PHFs underscores that phosphorylation is an important regulatory feature of tau function.”

GSK-3β may regulate tau toxicity through regulation of MARK-2/PAR-1.

“GSK-3β also may regulate tau toxicity through regulation of MARK-2/PAR-1.”

A reduction in sgg may suppress tau toxicity by allowing increased Armadillo to activate transcription of target genes.

“thus a reduction in sgg may suppress tau toxicity by allowing increased Armadillo to activate transcription of target genes.”

Hedgehog is linked computationally to the tau modifier network.

“thus, it may be expected that Hedgehog is linked computationally to the tau modifier network.”

The modifiers identified in this screen operate at different levels in tau toxicity.

“This also indicates that the modifiers identified in this screen operate at different levels in tau toxicity, providing a diverse range of therapeutic targets.”

The effect of ksr may not be as robust as sgg suppression due to decreased ERK activity also found with ksr.

“however, the effect of ksr may not be as robust as sgg suppression due to decreased ERK activity also found with ksr.”

Chaperones play a role in tauopathy.

“In our screen, LOF of Hop enhances tau toxicity, providing further evidence for the role of chaperones in tauopathy.”

The effects of KSR and NRG on tau toxicity may not be directly related to their role in ERK signaling.

“thus their effects on tau toxicity may not be directly related to their role in ERK signaling.”

An increase in cytoskeletal instability caused by reduced Nrg in a tau-induced hyperstabilized environment may result in alleviation of tau toxicity.

“therefore, an increase in cytoskeletal instability caused by reduced Nrg in a tau-induced hyperstabilized environment may result in alleviation of tau toxicity.”

Target of rapamycin-regulated autophagy is activated dose-dependently by white mutations.

“we observe a decrease in phospho-S6K in white homozygotes when compared with white hetereozygotes, suggesting that target of rapamycin-regulated autophagy is activated dose-dependently by white mutations (189).”

• cites [189] Ambegaokar, 2011, Double vision: pigment genes do more than just color, Fly sourceNot checked — no full text of the source

Disruption of lysosomal function leads to increased GSK-3β activity.

“Our results suggest that disruption of lysosomal function leads to increased GSK-3β activity.”

Reducing ERK activity is beneficial.

“suggesting that reducing ERK activity is beneficial.”

Tau may block neurensin-1 from microtubule binding, leading to impaired lysosomal trafficking when tau is over-abundant.

“Hence, tau may block neurensin-1 from microtubule binding, leading to impaired lysosomal trafficking when tau is over-abundant.”

The effects of ERK activity on toxicity may be secondary to effects on GSK-3β activity.

“The effects of ERK activity on toxicity, however, may be secondary to effects on GSK-3β activity.”

An antagonistic cross-talk takes place between ERK and p38 activities, with tau playing a modulatory role.

“These data indicate that an antagonistic cross-talk takes place between ERK and p38 activities, with tau playing a modulatory role.”

Autophagy is a protective process in tauopathy.

“We uncovered an LOF allele of Autophagy-specific gene 6 (Atg6), the Drosophila homolog of mammalian Beclin-1, that increases tau toxicity, further implicating autophagy as a protective process.”

ksr can also influence the GSK-3β pathway.

“To our knowledge, this is the first report that kinase suppressor of Ras (ksr), classically identified in the Ras-Raf-MAPK/ERK pathway, can also influence the GSK-3β pathway.”

Dysregulation of the autophagy-lysosomal pathway and GSK-3β activity is related.

“These observations suggest that dysregulation of autophagy-lysosomal pathway and GSK-3β activity is related; however, the nature of this relation appears to be very complex.”

The role of GSK-3β in tau toxicity may be more prominent in conditions where ERK activity is reduced.

“This may indicate that the role of GSK-3β in tau toxicity may be more prominent in conditions where ERK activity is reduced.”

The suppressive effect of ksr on Aβ42 and TDP-43 is due to reduced GSK-3β activity.

“We conclude that the suppressive effect of ksr on Aβ42 and TDP-43 is due to reduced GSK-3β activity”

bancal was considered to be the causative gene.

“thus, bancal was considered to be the causative gene”

The differences in modifiers obtained may be attributed to several differences in study design, namely the use of mutant tau (tauV337M), tau overexpression driven by GAL4/UAS constructs, and different collections of P element insertion lines used for screening.

“The differences in modifiers obtained may be attributed to several differences in study design, namely (i) the use of mutant tau (tauV337M), (ii) tau overexpression driven by GAL4/UAS constructs and (iii) different collections of P element insertion lines used for screening, i.e. P{EP} and P{Mae-UAS.6.11}.”

Tango5 was the causative gene.

“thus, Tango5 was the causative gene”

The network is validated to identify relevant tauopathic genes.

“Our computational network identified Npc1, the Drosophila homolog of NPC1, as highly associated with the modifier network, further validating the network to identify relevant tauopathic genes.”

The network identification of PSA helps to validate the applicability of the network.

“The network identification of PSA helps to validate the applicability of the network and suggests that calpains A, B and C are highly relevant proteases.”

The haploinsufficient basis of modifiers identified suggests that relatively small changes in key proteins or other gene products can strongly modify tau toxicity.

“However, the haploinsufficient basis of modifiers identified suggests that relatively small changes in key proteins or other gene products can strongly modify tau toxicity, which is encouraging for the development of therapeutic treatments and may assist in identifying biomarkers that are predictive of neurodegenerative tauopathies.”

Tau phosphorylation is not an indispensable factor in tauopathy.

“arguing against tau phosphorylation as an indispensable factor in tauopathy”

The mitotic failure/cell-cycle re-entry hypothesis of neurodegeneration is supported.

“A surprising number of modifiers identified from the screen play a role in regulating the cell cycle or chromatin binding, lending further credence to the mitotic failure/cell-cycle re-entry hypothesis of neurodegeneration.”

The data identify a novel set of targets for such alternative approaches.

“identify a novel set of targets for such alternatives”

Our data suggest smid may be more closely related to VCP functions.

“Reductions in VCP expression appear to suppress neurodegenerative effects, while increased torsin A expression is beneficial, suggesting different functional pathways, of which our data suggest smid may be more closely related to VCP functions.”

Tau is not a substrate of Smid.

“Smid is predicted to be a serine-type endopeptidase, although no substrates have been identified, and total tau protein levels and AT8 signal show no differences in trans to smid when compared with control, indicating that tau is not a substrate.”

CG31630 was considered as the modifying gene.

“thus CG31630 was considered as the modifying gene”

Our data further support an interaction between tau and ribosomes.

“Our data further support an interaction between tau and ribosomes.”

Altered Notch signaling does not underlie frc suppression of tau toxicity.

“A second allele of frc (frc0073) confirmed its suppressive effects on tau toxicity; however, none of the fng alleles tested (fngrG554, fng13, fngM69, fngL73, fng52) showed any effect on the tau phenotype, suggesting that altered Notch signaling does not underlie frc suppression of tau toxicity.”

The increased toxicity of RNA-associated modifier loss-of-function may be due to a reduced number of proteins able to sequester RNA away from tau.

“In nearly all RNA-associated modifiers identified in this screen, an LOF led to increased toxicity; this may be due to a reduced number of proteins able to sequester RNA away from the tau protein.”

Mechanisms independent of tau phosphorylation can alter toxicity.

“from which we conclude that mechanisms independent of tau phosphorylation can alter toxicity”

ksr may function as a link between both signal transduction systems.

“and may function as a link between both signal transduction systems”

The S262 and S356 sites are particularly important in producing toxicity.

“indicating that the S262 and S356 sites are particularly important in producing toxicity”

The design of the screen to identify modifiers of tau or tau toxicity is validated.

“In sum, 40 genetic modifiers were identified as strong modifiers of tau toxicity (Table 1); of these, sgg/GSK-3β and par-1/MARK-2 are known tau kinases, validating the design of the screen to identify modifiers of tau or tau toxicity.”

• AssumptionRests on an assumption: sgg/GSK-3β and par-1/MARK-2 are known tau kinases.

Increased cholesterol intake leads to cognitive impairments.

“It does seem clear that increased cholesterol intake leads to cognitive impairments (268), of which increased tau phosphorylation may contribute.”

• cites [268] Morley, 2010, Lipids and cognition, J. Alz. Dis. sourceNot checked — no full text of the source