BRI2 (ITM2b) Inhibits A Deposition In Vivo

Synthetic ABri and ADan are neurotoxic.

“Notably, synthetic ABri and ADan undergo rapid aggregation and fibrillization into amyloid, and they are neurotoxic (Gibson et al., 2005;Ghiso et al., 2006).”

• cites Gibson et al., 2005 sourceNot checked — no full text of the source
• cites Ghiso et al., 2006 sourcePartly supported

  The Abstract (page not provided) identifies ABri and ADan as amyloid peptides and reports that both form ion-channel-like structures in reconstituted membranes. The References name a study of ADan neurotoxicity, but the passages do not establish that synthetic ABri and ADan are both neurotoxic. (LLM, conf=0.68)

  Experimental — accuracy not yet measured

Aβ1-40 and Aβ42 have opposing effects on amyloid deposition in BRI2-Aβ transgenic mice crossed with Tg2576 mice.

“By crossing BRI2-A␤1-40 or BRI-A␤1-42 transgenic mice with Tg2576 mice, we previously demonstrated that A␤1-40 and A␤42 have opposing effects on amyloid deposition (McGowan et al., 2005;Kim et al., 2007).”

• cites McGowan et al., 2005 sourceNot checked — no full text of the source
• cites Kim et al., 2007 sourcePartly supported

  The Results section reports 60–90% less amyloid deposition in BRI-Aβ40/Tg2576 mice than in Tg2576 littermates. The Abstract states that Aβ42 promotes deposition while Aβ40 inhibits it, and the Generation of mice section says both BRI lines were crossed with Tg2576. But the passages do not establish the opposing effects on deposition by comparing both types of Tg2576 cross; the Aβ42 deposition evidence described in the Introduction concerns BRI-Aβ42 mice. (LLM, conf=0.84)

  Experimental — accuracy not yet measured

Synthetic ABri and ADan undergo rapid aggregation and fibrillization into amyloid.

“Notably, synthetic ABri and ADan undergo rapid aggregation and fibrillization into amyloid, and they are neurotoxic (Gibson et al., 2005;Ghiso et al., 2006).”

• cites Gibson et al., 2005 sourceNot checked — no full text of the source
• cites Ghiso et al., 2006 sourcePartly supported

  The Abstract identifies ABri and ADan as the main components of amyloid fibrils in familial British and Danish dementias. It does not establish that synthetic versions of both peptides aggregate or fibrillize rapidly; searches for “synthetic,” “aggregation,” and “fibrillization” found no passage reporting that behavior. (LLM, conf=0.82)

  Experimental — accuracy not yet measured

Cerebral accumulation of amyloidogenic peptides in familial British and familial Danish dementias and Alzheimer's disease is associated with neurodegeneration.

“Analyses of the biologic effects of mutations in the BRI2 (ITM2b) and the amyloid ␤ precursor protein (APP) genes support the hypothesis that cerebral accumulation of amyloidogenic peptides in familial British and familial Danish dementias and Alzheimer's disease (AD) is associated with neurodegeneration.”

• cites Golde, 2003 sourceSupported

The reduction in Aβ deposition in mice expressing the rAAV1 BRI2-Aβ1-40 transgene was consistent with previous transgenic mice studies.

“The reduction in A␤ deposition observed in the mice expressing the rAAV1 BRI2-A␤1-40 transgene was consistent with our previous transgenic mice studies (Kim et al., 2007), whereas the reduction of A␤ deposition observed in the mice expressing BRI2 was unexpected.”

• cites Kim et al., 2007 sourceSupported

The somatic brain transgenic BRI2-A␤1-40 studies confirmed previous studies using conventional transgenic mice expressing BRI2-A␤1-40.

“The studies with BRI2-A␤1-40 confirmed previous studies obtained using conventional transgenic mice expressing BRI2-A␤1-40 (McGowan et al., 2005;Kim et al., 2007).”

• cites McGowan et al., 2005 sourceNot checked — no full text of the source
• cites Kim et al., 2007 sourceSupported

Plasma Aβ1-42 levels were not significantly changed by BRI2 expression.

“BRI2-A␤1-40 expression slightly increased plasma A␤40 levels, attributable to brain to plasma efflux of A␤1-40; plasma A␤1-42 levels were not significantly changed by BRI2 expression (Fig. 2 D).”

There was no evidence for an anti-Aβ titer in any of the rAAV1-injected mice.

“There was no evidence for an anti-A␤ titer in any of the rAAV1injected mice (Fig. 2 F).”

Bri23 is present in human CSF.

“Additional data indicate that the 23 aa peptide, Bri23, released from BRI2 by normal processing, is present in human CSF, inhibits A␤ aggregation in vitro and mediates its anti-amyloidogenic effect in vivo.”

Expression of BRI2-Aβ1-40 mimics the suppressive effect on Aβ deposition previously observed using conventional transgenic methods.

“Expression of BRI2-A␤1-40 mimics the suppressive effect previously observed using conventional transgenic methods, further validating the somatic brain transgenic methodology.”

Levels of endogenous rodent Aβ in the brains of nontransgenic littermates of TgCRND8 mice expressing the BRI2 transgene were not altered.

“Moreover, levels of endogenous rodent A␤ levels in the brains of the nontransgenic littermates of the TgCRND8 mice expressing the BRI2 transgene were not altered (Fig. 2C).”

Expression of wild-type human BRI2 reduces cerebral Aβ deposition in an Alzheimer's disease mouse model.

“Unexpectedly, we also find that expression of wild-type human BRI2 reduces cerebral A␤ deposition in an AD mouse model.”

BRI2-Aβ1-40 expression slightly increased plasma Aβ40 levels.

“BRI2-A␤1-40 expression slightly increased plasma A␤40 levels, attributable to brain to plasma efflux of A␤1-40; plasma A␤1-42 levels were not significantly changed by BRI2 expression (Fig. 2 D).”

There is no evidence for alterations in the steady-state levels of APP or APP CTFβ in TgCRND8 mice expressing the virally delivered BRI2-Aβ1-40 or BRI2 transgenes.

“As in the studies of BRI2-A␤ transgenic mice crossed into Tg2576 mice (McGowan et al., 2005;Kim et al., 2007), we found no evidence for alterations in the steady-state levels of APP or APP CTF␤ in TgCRND8 mice expressing the virally delivered BRI2-A␤1-40 or BRI2 transgenes (Fig. 2 A, B).”

Addition of Bri2-23 or Aβ1-40 to the reaction resulted in retention of the monomeric Aβ1-42 signal, suggesting direct inhibition of aggregation.

“Addition of Bri2-23 or A␤1-40 to the reaction resulted in retention of the monomeric A␤1-42 signal, suggesting direct inhibition of aggregation (Fig. 3A, compare lane 10 with lanes 4, 6, and 8).”

rAAV1-mediated delivery of BRI2 to P0 Tg2576 did not lower steady-state Aβ levels in brains of 2-month-old mice.

“rAAV1-mediated delivery of BRI2 to P0 Tg2576 did not lower steady-state A␤ levels in brains of 2-month-old mice.(Fig. 2 E).”

• AssumptionRests on an assumption: Because of the rapid onset of Aβ deposition in TgCRND8 mice, it is not possible to measure steady-state Aβ levels.

Both BRI2-Aβ1-40 and BRI2 transgenes dramatically suppress parenchymal Aβ1-40 and Aβ1-42 accumulation as measured by biochemical and histochemical assessments of Aβ levels.

“These analyses revealed a dramatic suppressive effect of both the BRI2-A␤1-40 and BRI2 transgenes on parenchymal A␤1-40 and A␤1-42 accumulation as measured by biochemical and histochemical assessments of A␤ levels (Fig. 1C-E).”

Bri23 inhibits Aβ aggregation in vitro.

“Additional data indicate that the 23 aa peptide, Bri23, released from BRI2 by normal processing, is present in human CSF, inhibits A␤ aggregation in vitro and mediates its anti-amyloidogenic effect in vivo.”

The Bri2-23 peptide is present in human CSF.

“The Bri2-23 peptide is present in human CSF”

• Also stated in: § The Bri2-23 sequence is required to suppress A␤ deposition in vivo · plain

  “We then tested normal human CSF and were able to detect the endogenously secreted Bri2-23 peptide in all samples tested (Fig. 4G).”

• Also stated in: § Discussion · plain

  “Spectra from the CSF of three normal subjects each yielded a peak absent from the blank with an assessed mass-to-charge ratio nearly identical to the Bri2-23 peptide standard.”

Expression of the BRI2del244-266 construct that lacks a secreted peptide sequence has no effect on A␤ deposition after expression in vivo.

“We demonstrate that expression of the BRI2del244 -266 construct that lacks a secreted peptide sequence has no effect on A␤ deposition after expression in vivo.”

BRI2 suppresses A␤ deposition in APP CRND8 transgenic mice to an extent equivalent to A␤1-40.

“The novel result from these studies was the finding that BRI2 suppresses A␤ deposition in APP CRND8 transgenic mice to an extent equivalent to A␤1-40.”

• Also stated in: § Discussion · plain

  “BRI2 expression inhibits A␤ deposition in vivo.”

The expression of BRI2 did not lower the steady-state A␤ levels compared with control group in 2-month-old Tg2576 mice.

“The expression of BRI2 did not lower the steady-state A␤ levels compared with control group.”

Atomic force microscopy imaging confirmed the inhibitory effects of Bri2-23 on Aβ1-42 aggregation in these assays.

“Atomic force microscopy (AFM) imaging confirmed the inhibitory effects of Bri2-23 on A␤1-42 aggregation in these assays (Fig. 3D).”

Quantification of APP and CTF␤ protein level after normalization to ␤-actin level showed no change in the relative levels of both proteins in all groups.

“B, Quantification of APP and CTF␤ protein level after normalization to ␤-actin level showed no change in the relative levels of both proteins in all groups.”

Prolonged incubations of Bri2-23 by itself did not result in aggregation or β-sheet formation as assessed by ThT fluorescence assay, change in circular dichroism spectra, or insolubility.

“Prolonged incubations of Bri2-23, by itself, did not result in aggregation or ␤-sheet formation as assessed by ThT fluorescence assay, change in circular dichroism spectra, or insolubility (data not shown) (Gibson et al., 2005).”

• cites Gibson et al., 2005 sourceNot checked — no full text of the source

There is no significant difference in Aβ loads between BRI2del244-266 and control groups.

“Analyses of A␤ loads showed no significant difference between BRI2del244 -266 and the control groups (Fig. 4 B-D).”

The effect of Bri2-23 on retaining Aβ1-42 in its monomeric state was more robust with increasing concentrations of Bri2-23.

“Quantification by an ELISA capable of only recognizing monomeric A␤ confirmed that the Bri2-23 peptide retained A␤1-42 in its monomeric state, and this effect was more robust with increasing concentrations of Bri2-23 (Fig. 3B).”

The steady-state endogenous mouse A␤ levels in nontransgenic littermates of TgCNRD8 mice were comparable between PBS injection control and rAAV1-BRI2 group.

“C, The steady-state endogenous mouse A␤ levels in nontransgenic littermates of TgCNRD8 mice, measured by rodent A␤-specific ELISA, were comparable between PBS injection control and rAAV1-BRI2 group.”

Bri2-23 peptide inhibits A␤ aggregation in vitro.

“Bri2-23 peptide inhibits A␤ aggregation in vitro.”

• Also stated in: § Discussion · boosted

  “Coupled with their inhibition of aggregation in vitro, we conclude that the A␤1-40 and Bri2-23 peptides are directly responsible for reduced A␤ deposition in our experiments rather than any other part of the BRI2 protein scaffold on which they were delivered.”

No evidence was found that the suppressive effect of BRI2 on A␤ deposition was mediated by alterations in APP processing or A␤ production.

“Although it is not possible to completely rule out subtle effects on A␤ generation that could influence deposition, we found no evidence that the suppressive effect was mediated by alterations in APP processing or A␤ production.”

Cerebral expression of BRI2 and BRI2-A␤1-40 in TgCRND8 mice did not trigger anti-A␤ immune response in all groups, except in the positive control group immunized with fibrillar A␤42.

“Cerebral expression of BRI2 and BRI2-A␤1-40 in TgCRND8 mice did not trigger anti-A␤ immune response in all groups, except in the positive control group immunized with fibrillar A␤42.”

There was no change in plasma A␤ level in the BRI2 group compared with no injection control group.

“There was no change in A␤ level in BRI2 group, compared with no injection control group.”

Bri2-23 retained Aβ1-42 in its monomeric state as confirmed by an ELISA capable of only recognizing monomeric Aβ.

“Quantification by an ELISA capable of only recognizing monomeric A␤ confirmed that the Bri2-23 peptide retained A␤1-42 in its monomeric state, and this effect was more robust with increasing concentrations of Bri2-23 (Fig. 3B).”

BRI2-A␤1-40-injected TgCRND8 mice had significantly increased plasma A␤40 levels compared with no injection and BRI2 injection groups.

“BRI2-A␤1-40-injected TgCRND8 mice had significantly increased plasma A␤40 levels, compared with no injection and BRI2 injection groups (*p Ͻ 0.05).”

A␤42 levels were comparable between all groups.

“A␤42 levels were comparable between all groups ( p Ͼ 0.05).”

After 120-200 h of incubation, Bri2-23 inhibited Aβ1-42 aggregation by 46 ± 9% (n=6; p=0.0004).

“After 120 -200 h of incubation, Bri2-23 inhibited A␤1-42 aggregation by 46 Ϯ 9% (n ϭ 6; p ϭ 0.0004).”

Somatic brain transgenesis leads to consistent widespread and permanent expression of the transgene in forebrain and hippocampal neurons.

“This methodology of gene transfer, which we have termed somatic brain transgenesis, leads to consistent widespread and permanent expression of the transgene in forebrain and hippocampal neurons (Fig. 1 A) and enables one to rapidly and cost-effectively evaluate the effects of transgene expression on the amyloid deposition phenotype (Levites et al., 2006b).”

• cites Levites et al., 2006bNot matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

The increase in plasma Aβ40 levels is attributable to brain to plasma efflux of Aβ1-40.

“BRI2-A␤1-40 expression slightly increased plasma A␤40 levels, attributable to brain to plasma efflux of A␤1-40; plasma A␤1-42 levels were not significantly changed by BRI2 expression (Fig. 2 D).”

Biochemical and histochemical Aβ loads in the control groups were equivalent.

“Biochemical and histochemical A␤ loads in the control groups were equivalent.”

The 23 aa peptide Bri23 is released from BRI2 by normal processing.

“It is expressed at high levels in the brain and cleaved by furin or furin-like proteases at its C terminus to produce a 23 aa peptide (Bri2-23) (Kim et al., 1999;Choi et al., 2004) (Fig. 1 B).”

• cites Kim et al., 1999 sourceNot checked — no full text of the source
• cites Choi et al., 2004Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Somatic brain transgenesis enables rapid and cost-effective evaluation of the effects of transgene expression on the amyloid deposition phenotype.

“This methodology of gene transfer, which we have termed somatic brain transgenesis, leads to consistent widespread and permanent expression of the transgene in forebrain and hippocampal neurons (Fig. 1 A) and enables one to rapidly and cost-effectively evaluate the effects of transgene expression on the amyloid deposition phenotype (Levites et al., 2006b).”

• cites Levites et al., 2006bNot matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

The reduction of Aβ accumulation by BRI2 and BRI2-Aβ1-40 transgenes was not likely attributable to alterations in APP processing resulting from altered Aβ production or induction of an anti-Aβ immune response.

“Collectively, these results in TgCRND8, wild-type TgCRND8 littermates, and Tg2576 mice demonstrate that the reduction of A␤ accumulation by BRI2 and BRI2-A␤1-40 transgenes was not likely to be attributable to alterations in APP processing resulting from altered A␤ production or induction of an anti-A␤ immune response.”

• AssumptionRests on an assumption: Anti-Aβ antibodies reduce Aβ deposition in mice.
• AssumptionRests on an assumption: Expression of virally encoded Aβ peptides in the periphery generates an anti-Aβ response.

There are clear pathological and clinical similarities between FBD, FDD, and Alzheimer's disease.

“Thus, there are clear pathological and clinical similarities between FBD, FDD, and Alzheimer's disease (AD).”

Bri23 mediates the anti-amyloidogenic effect of BRI2 in vivo.

“Additional data indicate that the 23 aa peptide, Bri23, released from BRI2 by normal processing, is present in human CSF, inhibits A␤ aggregation in vitro and mediates its anti-amyloidogenic effect in vivo.”

BRI2 is a novel mediator of Aβ deposition in vivo.

“These studies demonstrate that BRI2 is a novel mediator of A␤ deposition in vivo.”

BRI2 has an anti-amyloidogenic function mediated by the Bri2-23 peptide.

“Together with the data demonstrating that Bri2-23 directly inhibits A␤ aggre- gation in vitro, these data support an anti-amyloidogenic function for BRI2 mediated by the Bri2-23 peptide.”

We validated the HPLC/MS methodology by detecting untagged Bri2-23 peptide secretion from H4 cells transfected with BRI2 but not BRIdel244-266.

“We validated this methodology by detecting untagged Bri2-23 peptide secretion from H4 cells transfected with BRI2 but not BRIdel244 -266 (Fig. 4 F).”

• Also stated in: § Discussion · plain

  “Synthetic Bri2-23 yielded a peak that was in excellent agreement with its predicted mass-to-charge ratio (m/z) of 2630.”

• Also stated in: § Discussion · plain

  “Spectra from the conditioned media of cells transiently transfected with pcDNA3-BRI2 yielded a peak absent from both the blank and conditioned media from cells transfected with pcDNA3 BRI2del-244 -266.”

Bri2-23 contains the sequence FENKF that is homologous to peptide-based A␤ aggregation inhibitors incorporating a FxxxF motif.

“In support of our observations, Bri2-23 contains the sequence FENKF that is homologous to peptide-based A␤ aggregation inhibitors incorporating a FxxxF motif (Sato et al., 2006).”

• cites Sato et al., 2006 sourceNot checked — no full text of the source

The Bri2-23 peptide sequence is critical for the inhibitory effect of BRI2 in vivo.

“These later data and the lack of anti-amyloidogenic effect from BRI2del244 -266 demonstrate that the Bri2-23 peptide sequence is critical for the inhibitory effect of BRI2 in vivo.”

The anti-amyloidogenic effect of the BRI2 protein is mediated by an interaction between Bri2-23 and Aβ.

“These observations suggested that the anti-amyloidogenic effect of the BRI2 protein is mediated by an interaction between Bri2-23 and A␤.”

The anti-aggregation effects of Bri2-23 peptide may be physiologically relevant to human AD, FDD, and FBD.

“This finding strengthens the notion that the anti-aggregation effects of Bri2-23 peptide in our experiments may be physiologically relevant to human AD, FDD, and FBD.”

Endogenous BRI2 could function, at least in part, by secretion of the Bri2-23 peptide as an antiamyloidogenic binding partner of A␤.

“Our mouse data suggested that endogenous BRI2 could function, at least in part, by secretion of the Bri2-23 peptide as an antiamyloidogenic binding partner of A␤.”

These data support a novel approach to AD therapy or prevention based on increasing levels of BRI2 and more specifically the Bri2-23 peptide in the brain.

“These data support a novel approach to AD therapy or prevention based on increasing levels of BRI2 and more specifically the Bri2-23 peptide in the brain.”

The A␤1-40 and Bri2-23 peptides are directly responsible for reduced A␤ deposition in our experiments rather than any other part of the BRI2 protein scaffold on which they were delivered.

“Coupled with their inhibition of aggregation in vitro, we conclude that the A␤1-40 and Bri2-23 peptides are directly responsible for reduced A␤ deposition in our experiments rather than any other part of the BRI2 protein scaffold on which they were delivered.”

• AssumptionRests on an assumption: BRI2del244-266 encodes a protein containing the region of BRI2 previously shown to interact with APP and interfere with APP processing in cell culture.
• AssumptionRests on an assumption: BRI2 and BRI2-A␤1-40 are cleaved by furin and other kex2 proteases to release Bri2-23 and A␤1-40, respectively.

BRI2 is a novel factor that modulates A␤ aggregation and deposition.

“The robust inhibitory effect of BRI2 on A␤ deposition in vivo and aggregation in vitro BRI2 indicates that BRI2 is a novel factor that modulates A␤ aggregation and deposition.”

BRI2del244-266 does not encode the Bri2-23 peptide.

“BRI2del244 -266 construct does not encode the Bri2-23 peptide.”

The Bri2-23 peptide is required for the anti-amyloidogenic effect of the BRI2 protein in vivo.

“The Bri2-23 peptide is required for the anti-amyloidogenic effect of the BRI2 protein in vivo and is present in human CSF.”

The FDD-linked BRI2 mutation may corrupt a normally protective anti-amyloidogenic mechanism resulting in coaggregation of the mutant peptide with a normal binding partner.

“These later findings suggest that the FDD-linked BRI2 mutation may corrupt a normally protective anti-amyloidogenic mechanism resulting in coaggregation of the mutant peptide with a normal binding partner.”

Solid-state nuclear magnetic resonance analysis demonstrated direct binding of an 8 aa peptide containing the sequence FEGKF with the glycine zipper (G33xxxG37) segment of A␤1-40, a sequence proposed to be critical for formation and stability of ␤-sheet structure.

“Moreover, solid-state nuclear magnetic resonance analysis demonstrated direct binding of an 8 aa peptide containing the sequence FEGKF with the glycine zipper (G33xxxG37) segment of A␤1-40, a sequence proposed to be critical for formation and stability of ␤-sheet structure (Liu et al., 2005;Sato et al., 2006).”

• cites Liu et al., 2005 sourceNot checked — no full text of the source
• cites Sato et al., 2006 sourceNot checked — no full text of the source

The suppressive effect of BRI2 on A␤ deposition is likely mediated by inhibition of A␤ aggregation by the secreted peptide.

“Instead, we find that the suppressive effect of BRI2 is likely to be mediated by inhibition of A␤ aggregation by the secreted peptide.”

• AssumptionRests on an assumption: BRI2 and BRI2-A␤1-40 are cleaved by furin and other kex2 proteases to release Bri2-23 and A␤1-40, respectively.

The somatic brain transgenic BRI2-A␤1-40 studies provide additional validation for this rapid cost-effective method of manipulating gene expression in the brain.

“Thus, the somatic brain transgenic BRI2-A␤1-40 studies provide additional validation for this rapid cost-effective method of manipulating gene expression in the brain (Levites et al., 2006b).”

• cites Levites et al., 2006bNot matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Somatic brain transgenesis results in consistent transduction of forebrain and hippocampal neurons.

“A, Somatic brain transgenesis results in consistent transduction of forebrain and hippocampal neurons.”