Tuberous Sclerosis Protein 2 (TSC2) Modulates CCN4 Cytoprotection During Apoptotic Amyloid Toxicity in Microglia

Probably not a substantial claim: may not pass S3 (load-bearing).

During periods of oxidative stress, loss of TSC2 results in Purkinje cell degeneration.

“During periods of oxidative stress, loss of the TSC2 results in purkinje cell degeneration [44].”

• cites [44] Reith RM Way S McKenna J 3rd Haines K Gambello MJ Loss of the tuberous sclerosis complex protein tuberin causes Purkinje cell degeneration Neurobiol Dis 2011 43 1 113 122 21419848 PMC3096682 sourceSupported

Probably not a substantial claim: may not pass S3 (load-bearing).

Neurons without a functional TSC1/TSC2 complex have increased vulnerability to endoplasmic reticulum stress-induced cell death through activation of the mitochondrial death pathway.

“neurons without a functional TSC1/TSC2 complex have been shown to have increased vulnerability to endoplasmic reticulum stress-induced cell death through the activation of the mitochondrial death pathway [55].”

• cites [55] Di Nardo A Kramvis I Cho N Sadowski A Meikle L Kwiatkowski DJ Tuberous sclerosis complex activity is required to control neuronal stress responses in an mTOR-dependent manner J Neurosci 2009 29 18 5926 5937 19420259 PMC2691854 sourceSupported

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Apoptosis in cells involves both an early phase consisting of exposure of membrane PS residues and a late phase involving destruction of genomic DNA.

“Apoptosis in cells involves both an early phase consisting of the exposure of membrane PS residues and a late phase that involves the destruction of genomic DNA [23, 45–47].”

• cites [23] Maiese K Chong ZZ Wang S Shang YC Oxidant Stress and Signal Transduction in the Nervous System with the PI 3-K, Akt, and mTOR Cascade International journal of molecular sciences 2012 13 11 13830 13866 23203037 PMC3509553 sourceSupported
• cites [45] Chong ZZ Li F Maiese K Oxidative stress in the brain: Novel cellular targets that govern survival during neurodegenerative disease Prog Neurobiol 2005 75 3 207 246 15882775 sourceNot checked — no full text of the source
• cites [46] Maiese K Chong ZZ Shang YC OutFOXOing disease and disability: the therapeutic potential of targeting FoxO proteins Trends Mol Med 2008 14 5 219 227 18403263 PMC2572150 sourceCould not verify

  The Introduction discusses FoxO-related apoptotic pathways, but does not describe membrane phosphatidylserine exposure as an early phase or genomic DNA destruction as a late phase. Searches for those terms found only related reference titles, not a passage in this paper stating the claimed sequence. (LLM, conf=0.72)

  Experimental — accuracy not yet measured
• cites [47] Maiese K Chong ZZ Shang YC Wang S Targeting disease through novel pathways of apoptosis and autophagy Expert opinion on therapeutic targets 2012 (in press). PMC3500415 22924465 sourceSupported

Probably not a substantial claim: may not pass S3 (load-bearing).

The TSC1/TSC2 complex is a negative regulator of mTORC1 by controlling the activity of Rheb.

“The TSC1/TSC2 complex is a negative regulator of mTORC1 by controlling the activity of Ras homologue enriched in brain (Rheb).”

• cites [24] Chong ZZ Maiese K Mammalian Target of Rapamycin Signaling in Diabetic Cardiovascular Disease Cardiovasc Diabetol 2012 11 1 45 22545721 PMC3398846 sourceCould not verify

  The section “mTOR signaling in diabetic cardiovascular disease” mentions TSC1/TSC2 in relation to IRS1 inhibition, not regulation of Rheb. A reference title links Rheb to increased mTORC1 signaling, but no passage found states that TSC1/TSC2 negatively regulates mTORC1 by controlling Rheb (searched: TSC1/TSC2, Rheb, and tuberous sclerosis complex). Page numbers were unavailable in our copy. (LLM, conf=0.73)

  Experimental — accuracy not yet measured
• cites [25] Chong ZZ Shang YC Maiese K Cardiovascular Disease and mTOR Signaling Trends Cardiovasc Med 2011 21 5 151 155 22732551 PMC3384484 sourcePartly supported

  The Stem cell proliferation section (page not provided) says that phosphorylation of TSC2 results in inhibition of mTOR activity, supporting a negative regulatory role for TSC2. It does not establish that the TSC1/TSC2 complex regulates mTORC1 by controlling Rheb activity. (LLM, conf=0.82)

  Experimental — accuracy not yet measured

May combine two claims.

WISP1 promotes cytoprotection in multiple cell types through pathways that require PI 3-K and Akt and, in microglia, involve mTOR and PRAS40.

“WISP1 promotes cytoprotection in multiple cell types through pathways that not only require phosphatidylinositol-3-kinase (PI 3-K) and protein kinase B (Akt) [7, 8, 10, 11, 20, 21], but also utilize pathways in microglia that involve the mammalian target of rapamycin (mTOR) and the proline rich Akt substrate 40 kDa (PRAS40) [13].”

• cites [7] Su F Overholtzer M Besser D Levine AJ WISP-1 attenuates p53-mediated apoptosis in response to DNA damage through activation of the Akt kinase Genes Dev 2002 1 1 16 1 46 57 11782444 PMC155313 sourcePartly supported

  The section ‘WISP-1 inhibition of apoptosis requires Akt activity’ (page unavailable) reports that blocking Akt attenuated WISP-1’s protection against DNA-damage-induced apoptosis in H460 cells. The paper supports an Akt-dependent protective effect in that setting, but does not establish that PI 3-K is required or that the effect occurs across multiple cell types. The microglial mTOR/PRAS40 mechanism is separately attributed to citation [13], not this source. (LLM, conf=0.87)

  Experimental — accuracy not yet measured
• cites [8] Venkatesan B Prabhu SD Venkatachalam K Mummidi S Valente AJ Clark RA WNT1-inducible signaling pathway protein-1 activates diverse cell survival pathways and blocks doxorubicin-induced cardiomyocyte death Cell Signal 2010 5 22 5 809 820 20074638 PMC2885703 sourceSupported
• cites [10] Wang S Chong ZZ Shang YC Maiese K Wnt1 inducible signaling pathway protein 1 (WISP1) blocks neurodegeneration through phosphoinositide 3 kinase/Akt1 and apoptotic mitochondrial signaling involving Bad, Bax, Bim, and Bcl-xL Curr Neurovasc Res 2012 2 9 1 20 31 22272766 PMC3274638 sourceSupported
• cites [11] Wang S Chong ZZ Shang YC Maiese K WISP1 (CCN4) autoregulates its expression and nuclear trafficking of beta-catenin during oxidant stress with limited effects upon neuronal autophagy Curr Neurovasc Res 2012 4 4 9 2 89 99 PMC3354035 22475393 sourceSupported
• cites [20] Colston JT de la Rosa SD Koehler M Gonzales K Mestril R Freeman GL Wnt-induced secreted protein-1 is a prohypertrophic and profibrotic growth factor Am J Physiol Heart Circ Physiol 2007 9 293 3 H1839 H1846 17616748 sourceNot checked — no full text of the source
• cites [21] Reddy VS Valente AJ Delafontaine P Chandrasekar B Interleukin-18/WNT1-inducible signaling pathway protein-1 signaling mediates human saphenous vein smooth muscle cell proliferation J Cell Physiol 2011 12 226 12 3303 3315 21321938 PMC3111842 sourcePartly supported

  The Results section on WISP1-induced VSMC proliferation (page unavailable) shows that blocking PI3K or Akt attenuated proliferation, and the Discussion (page unavailable) reports induction of the pro-survival proteins survivin and Bcl-2 in these cells. The paper does not establish that cytoprotection across multiple cell types requires PI3K and Akt. The microglial mTOR/PRAS40 clause is attached to a different citation, not this paper. (LLM, conf=0.85)

  Experimental — accuracy not yet measured
• cites [13] Shang YC Chong ZZ Wang S Maiese K WNT1 Inducible Signaling Pathway Protein 1 (WISP1) Targets PRAS40 to Govern beta-Amyloid Apoptotic Injury of Microglia Curr Neurovasc Res 2012 8 6 9 4 239 249 22873724 PMC3521866 sourceSupported

Classified as probably not a substantial claim.

AMPK can inhibit mTOR activity.

“AMP activated protein kinase (AMPK), which can inhibit mTOR activity [41, 42]”

• cites [41] Chong ZZ Shang YC Wang S Maiese K Shedding new light on neurodegenerative diseases through the mammalian target of rapamycin Prog Neurobiol 2012 99 2 128 148 22980037 PMC3479314 sourceSupported
• cites [42] Gwinn DM Shackelford DB Egan DF Mihaylova MM Mery A Vasquez DS AMPK phosphorylation of raptor mediates a metabolic checkpoint Mol Cell 2008 30 2 214 226 18439900 PMC2674027 sourceNot checked — no full text of the source

May combine two claims.

WISP1 has been shown to be protective against oxidative stress in neurons and to block amyloid toxicity in inflammatory microglia of the brain.

“WISP1 has been shown to be protective against oxidative stress in neurons [10–12] and to block amyloid toxicity in inflammatory microglia of the brain [13].”

• cites [10] Wang S Chong ZZ Shang YC Maiese K Wnt1 inducible signaling pathway protein 1 (WISP1) blocks neurodegeneration through phosphoinositide 3 kinase/Akt1 and apoptotic mitochondrial signaling involving Bad, Bax, Bim, and Bcl-xL Curr Neurovasc Res 2012 2 9 1 20 31 22272766 PMC3274638 sourceSupported
• cites [11] Wang S Chong ZZ Shang YC Maiese K WISP1 (CCN4) autoregulates its expression and nuclear trafficking of beta-catenin during oxidant stress with limited effects upon neuronal autophagy Curr Neurovasc Res 2012 4 4 9 2 89 99 PMC3354035 22475393 sourceSupported
• cites [12] Wang S Chong ZZ Shang YC Maiese K WISP1 neuroprotection requires FoxO3a post-translational modulation with autoregulatory control of SIRT1 Curr Neurovasc Res 2012 11 12 (in press). PMC3568221 23151077 sourceSupported
• cites [13] Shang YC Chong ZZ Wang S Maiese K WNT1 Inducible Signaling Pathway Protein 1 (WISP1) Targets PRAS40 to Govern beta-Amyloid Apoptotic Injury of Microglia Curr Neurovasc Res 2012 8 6 9 4 239 249 22873724 PMC3521866 sourceSupported

Probably not a substantial claim: may not pass S3 (load-bearing).

Some studies have suggested that inhibition of mTOR activity may lead to cognitive improvement in mouse models of AD.

“Some studies have suggested that inhibition of mTOR activity may lead to cognitive improvement in mouse models of AD [54].”

• cites [54] Spilman P Podlutskaya N Hart MJ Debnath J Gorostiza O Bredesen D Inhibition of mTOR by rapamycin abolishes cognitive deficits and reduces amyloid-beta levels in a mouse model of Alzheimer's disease PLoS One 2010 5 4 e9979 20376313 PMC2848616 sourceSupported

Classified as probably not a substantial claim. May combine two claims.

mTOR phosphorylates and activates p70S6K at threonine389 and is a marker of mTOR activity.

“mTOR phosphorylates and activates p70S6K at threonine389 and is a marker of mTOR activity [40].”

• cites [40] Pearson RB Dennis PB Han JW Williamson NA Kozma SC Wettenhall RE The principal target of rapamycin-induced p70s6k inactivation is a novel phosphorylation site within a conserved hydrophobic domain Embo J 1995 14 21 5279 5287 7489717 PMC394637 sourcePartly supported

  The mutational-analysis section finds that phosphorylation of p70S6K at T389 is critical for its activity. The Discussion does not establish that mTOR (FRAP/RAFT1) directly phosphorylates that site: it says FRAP/RAFT1's upstream role remained to be determined and considers a phosphatase-based alternative. The paper also does not identify T389 phosphorylation as a marker of mTOR activity. Page numbers were not available in our copy. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

May combine two claims.

Loss of TSC2 in untreated cultures and during Aβ exposure alone did not increase membrane PS exposure.

“Loss of TSC2 in untreated cultures and during Aβ exposure alone did not increase membrane PS exposure.”

May combine two claims.

WISP1 (10 ng/ml) administered 1 hour prior to Aβ exposure significantly increased the red/green fluorescence intensity of mitochondria in microglia and preserved mitochondrial membrane polarization.

“WISP (10 ng/ml) administrated 1 hour prior to Aβ exposure significantly increased the red/green fluorescence intensity of mitochondria in microglia and preserved mitochondrial membrane polarization.”

May combine two claims.

Transfection with TSC2 shRNA prior to Aβ exposure impaired the ability of WISP1 to protect against cell injury and apoptosis and resulted in increased trypan blue dye exclusion and TUNEL staining.

“transfection with TSC2 shRNA prior to Aβ exposure impaired the ability of WISP1 to protect against cell injury and apoptosis and resulted in increased trypan blue dye exclusion and TUNEL staining.”

May combine two claims.

Gene silencing of TSC2 in untreated microglia and during Aβ exposure alone significantly increased p-p70S6K expression, but to a lesser extent than TSC2 silencing combined with WISP1.

“Gene silencing of TSC2 in untreated microglia and during Aβ exposure alone also significantly increased p-p70S6K expression but to a lesser extent than observed during gene silencing of TSC2 and combined WISP1 application”

May combine two claims.

WISP1 (10 ng/ml) administration prevented cytochrome c release and decreased the expression of cytochrome c in the cytosol during Aβ exposure.

“WISP1 (10 ng/ml) administration prevented cytochrome c release and decreased the expression of cytochrome c in the cytosol during Aβ exposure.”

May combine two claims.

Loss of TSC2 significantly reduced the ability of WISP1 to protect microglia during Aβ exposure, resulting in an increase in percent trypan blue staining (27 ± 7%) and TUNEL labeling (28 ± 8%).

“loss of TSC2 significantly reduced the ability of WISP1 to protect microglia during Aβ exposure, resulting in an increase in percent trypan blue staining (27 ± 7%) and TUNEL labeling (28 ± 8%).”

May combine two claims.

Scrambled shRNA during Aβ exposure did not injure cells in normal cultures or alter cell injury during Aβ exposure when compared to Aβ exposure alone.

“Scrambled shRNA during Aβ exposure did not injury cells in normal cultures or alter cell injury during Aβ exposure when compared to Aβ exposure alone.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Annexin V images were acquired with blinded assessment.

“Images were acquired with “blinded” assessment with a Leitz DMIRB microscope (Leica, McHenry, IL) and a Fuji/Nikon Super CCD (6.1 megapixels) using transmitted light and fluorescent single excitation light at 490 nm and detected emission at 585 nm.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Activation of AMPK can block mTOR and mTORC1 activity by phosphorylating and activating TSC2.

“activation of AMP activated protein kinase (AMPK), such as during decreased energy states, can block mTOR and mTORC1 activity by phosphorylating and activating TSC2 [29, 30].”

• cites [29] Inoki K Zhu T Guan KL TSC2 mediates cellular energy response to control cell growth and survival Cell 2003 115 5 577 590 26 14651849 sourceNot checked — no full text of the source
• cites [30] Sofer A Lei K Johannessen CM Ellisen LW Regulation of mTOR and cell growth in response to energy stress by REDD1 Mol Cell Biol 2005 25 14 5834 5845 15988001 PMC1168803 sourceNot checked — no full text of the source

Classified as probably not a substantial claim.

TSC2 blocks mTOR activity.

“tuberous sclerosis complex 2 (TSC2), that also blocks mTOR activity [26]”

• cites [26] Inoki K Li Y Zhu T Wu J Guan KL TSC2 is phosphorylated and inhibited by Akt and suppresses mTOR signalling Nat Cell Biol 2002 4 9 648 657 12172553 sourceNot checked — no full text of the source

Classified as probably not a substantial claim. May combine two claims.

For each experimental condition, 8 dishes were used, mean survival was determined by counting eight randomly selected non-overlapping fields containing approximately 20 cells, and each experiment was replicated 6 times with different cultures.

“For each experimental condition, 8 × 35 mm2 dishes were used, and for each dish, the mean survival was determined by counting eight randomly selected non-overlapping fields with each containing approximately 20 cells (viable + non-viable). Each experiment was replicated 6 times with different cultures.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

TSC2 functions as a GTPase-activating protein to convert active Rheb-GTP to inactive Rheb-GDP, resulting in inhibition of mTOR, the mTORC1 complex, and the mTOR signaling pathway p70S6K.

“TSC2, also known as tuberous sclerosis protein 2, functions as a GTPase-activating protein (GAP) to convert active Rheb-GTP to the inactive GDP-bound form (Rheb-GDP) resulting in the inhibition of mTOR, the mTORC1 complex [26], and the mTOR signaling pathway p70S6K [27].”

• cites [26] Inoki K Li Y Zhu T Wu J Guan KL TSC2 is phosphorylated and inhibited by Akt and suppresses mTOR signalling Nat Cell Biol 2002 4 9 648 657 12172553 sourceNot checked — no full text of the source
• cites [27] Manning BD Tee AR Logsdon MN Blenis J Cantley LC Identification of the tuberous sclerosis complex-2 tumor suppressor gene product tuberin as a target of the phosphoinositide 3-kinase/akt pathway Mol Cell 2002 10 1 151 162 12150915 sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing).

Some studies suggest that inhibition of the mTOR pathway in cancer cells may not adversely influence apoptosis through the mitochondrial pathway.

“some studies suggest that inhibition of the mTOR pathway in cancer cells may not adversely influence apoptosis through the mitochondrial pathway [56].”

• cites [56] Gazitt Y Kolaparthi V Moncada K Thomas C Freeman J Targeted therapy of human osteosarcoma with 17AAG or rapamycin: characterization of induced apoptosis and inhibition of mTOR and Akt/MAPK/Wnt pathways Int J Oncol 2009 34 2 551 561 19148492Not checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

TSC2 can be inhibited by Akt phosphorylation that destabilizes TSC2 and disrupts its interaction with TSC1.

“Subsequently, TSC2 can be inhibited by Akt phosphorylation that serves to destabilize TSC2 and disrupt its interaction with TSC1 [26, 28].”

• cites [26] Inoki K Li Y Zhu T Wu J Guan KL TSC2 is phosphorylated and inhibited by Akt and suppresses mTOR signalling Nat Cell Biol 2002 4 9 648 657 12172553 sourceNot checked — no full text of the source
• cites [28] Potter CJ Pedraza LG Xu T Akt regulates growth by directly phosphorylating Tsc2 Nat Cell Biol 2002 4 9 658 665 12172554 sourceNot checked — no full text of the source

May combine two claims.

WISP1/CCN4 controls the post-translational phosphorylation of Akt1, p70S6K, and AMPK such that TSC2 (Ser1387) phosphorylation is decreased and TSC2 (Thr1462) phosphorylation is increased.

“Here we show that Wnt1 inducible signaling pathway protein 1 (WISP1/CCN4) controls the post-translational phosphorylation of Akt1, p70S6K, and AMP activated protein kinase (AMPK) to the extent that tuberous sclerosis complex 2 (TSC2) (Ser1387) phosphorylation, a target of AMPK, is decreased and TSC2 (Thr1462) phosphorylation, a target of Akt1, is increased.”

Probably not a substantial claim: may not pass S3 (load-bearing).

For each shRNA assay, scrambled shRNA and an empty plasmid were used as controls.

“For each shRNA assay, scrambled shRNA and an empty plasmid were used as controls.”