- Email: [email protected]
P3-293: Interaction between amyloid-beta peptides with butyrylcholinesterase and ApoE proteins: Mechanism of amyloid fibrils deposition in the brain of patients with Alzheimer's disease
T608
Poster Presentations P3:
tion of A in the CA1 neurons correlates spatially and temporarily (t 1/2⬃ 1 week) with the accumulation of intraneuronal apoE in these neurons. Furthermore, these effects are associated with the loss of CA1 neurons synapses and with the occurrence of pronounced learning and memory deficits. Conclusions: These findings provide the first in vivo evidence regarding the cellular mechanisms underlying the pathological cross talk between apoE4 and A, as well as a novel model system of neurodegeneration in vivo that is uniquely suitable for studying the early stages of the amyloid cascade and the effects thereon of apoE4. P3-292
ASSOCIATION OF APOLIPOPROTEIN E AND SERUM ABETA LEVELS IN MEN UNDERGOING INTERMITTENT ANDROGEN ABLATION
Monique Cherrier, Patti Green, Gerald Schellenberg, Celestia Higano, University of Washington, Seattle, WA, USA. Contact e-mail: [email protected] Background: Declines in serum testosterone levels from aging is a risk factor for Alzheimer’s disease (AD). It has been suggested that increased risk for AD may be conferred through androgen regulation of beta-amyloid (abeta) accumulation which is believed to be a critical step in the cascade of AD pathogenesis. Recent evidence has shown that androgens regulate abeta in neuronal cell cultures and in a transgenic mouse model of AD. Methods: In the present study, we examined serum levels of abeta 1-40, 42 in men undergoing intermittent androgen deprivation therapy (ADT) for prostate cancer. Twenty hormone naı¨ve, eugonadal prostate cancer patients without evidence of metastases and with a rising PSA were treated with intermittent ADT consisting of nine months of leuprolide and flutamide followed by an “off treatment” period. Cognitive function tests were administered at baseline, after three and nine months of ADT and after three months of no treatment and blood samples were taken at these sessions. Results: As expected, serum levels of testosterone (T) were reduced significantly to castrate levels (p⬍.01) and estradiol levels were reduced approximately 50% (p⬍.05). ADT patients evidenced a significant decline in spatial reasoning, spatial abilities and working memory during treatment compared to baseline. Serum abeta 1-40, 42 levels were reduced significantly over time (p⬍.01) with an increase in the abeta42/40 ratio. However, when ADT patients were divided according to APOE status (apolipoprotein ⑀4 allele (APOE*4/4 and APOE*3/4 ⫽ APOE positive; all else ⫽ APOE negative) serum abeta 1-40, 42 levels increased only in the APOE*4 positive group and not in the APOE negative group and serum abeta 42/40 ratio decreased. Conclusions: These findings suggest that in humans, androgen regulation of abeta may be further modulated by the apolipoprotein ⑀4 allele. This is consistent with findings of T mediated modulation of cognitive impairments in the transgenic human APOE mouse model. P3-293
INTERACTION BETWEEN AMYLOID-BETA PEPTIDES WITH BUTYRYLCHOLINESTERASE AND APOE PROTEINS: MECHANISM OF AMYLOID FIBRILS DEPOSITION IN THE BRAIN OF PATIENTS WITH ALZHEIMER’S DISEASE
Taher Darreh-Shori1, Anton Forsberg1, Niels Andreasen1, Kaj Blennow2, Anders Wall3, Chelenk Kamil1, Bengt Långstro¨m3, Agneta Nordberg1, 1Karolinska Institutet, Stockholm, Sweden; 2 Gotenberg University, Gotenberg, Sweden; 3Imanet Uppsala, Uppsala, Sweden. Contact e-mail: [email protected] Background: We have previously shown that high age, ApoE4 and female gender (three AD risk factors) confer differential levels of circulating BuChE protein in CSF of AD patients. We hypothesize that CSF BuChE is inversely related to its deposition in amyloid plaques in the AD brain so that low level of BuChE in CSF may be predictive of higher degree of neurodegeneration due to an extensive incorporation of BuChE in neuritic plaques and the consequential increased neurotoxicity of plaques. Methods: BuChE and ApoE levels in plasma and CSF
of ninety mild AD patients were measured. Cerebral glucose utilization (CMRglc) was assessed by FDG-PET in 44 of the patients, whereas cerebral amyloid by PIB-PET in 26 patients. Results: The AD risk factors conferred differential level of ApoE protein in CSF of the patients. The CSF level of ApoE was increased with age (r⫽0.30, p⬍0.0006). Women and the carriers of ApoE e4 allele (in a gene-dose manner) had 40-45% higher level of ApoE protein in their CSF (p⬍0.01-0.002). These findings are similar to what we previously reported for the BuChE in CSF but in the opposite direction. Indeed, the CSF ApoE level showed a strong negative correlation with the BuChE level (r⫽0.47, p⬍0.0001). We also found that patients with high CSF BuChE had also a high soluble APP (r⫽0.59, p⬍0.006) and A-beta40 (r⫽0.45, p⬍0.05) in CSF. Preliminary functional assay of the BuChE suggested that the specific activity of BuChE was decreased in the CSF in an ApoE protein concentration-dependent manner. Remarkably, a high ratio of BuChE/ApoE protein was associated with a low amyloid load (PIB retention, r⫽ - 0.49, p⬍0.006) and a high rate of the cerebral glucose utilization (r⫽0.38, p⬍0.01) in the majority of cortical brain regions of the patients. Conclusions: These observations strongly support our hypothesis and suggest that high levels of ApoE protein in the brain may facilitate an extensive incorporation of BuChE in the A-beta deposits and conversion of benign plaques into the neuritic plaques. Further analysis are however needed to understand in details the proposed molecular interactions between ApoE, BuChE and A-beta fibrils in AD patients. P3-294
POST-TRANSLATIONAL MODIFICATIONS OF APOLIPOPROTEIN-E IN THE HUMAN BRAIN
David A. Elliott, Woojin S. Kim, Glenda M. Halliday, Brett Garner, Prince of Wales Medical Research Inst, Randwick, Australia. Contact e-mail: [email protected] Background: Polymorphism of apolipoprotein-E (apoE) is the greatest genetic risk factor for developing Alzheimer’s Disease (AD). We have investigated the influence of polymorphism and disease status on apoE post-translational modification in the human brain. Methods: Human brain homogenate samples were prepared from hippocampal, frontal and occipital regions obtained from AD and control donors of known apoE genotype. ApoE was examined by western blot under either reducing or non-reducing conditions. ApoE was also examined in SKNSH neuronal cells and rabbit brain homogenate prepared immediately after death. Results: A greater percentage of apoE was present as fragmentation products in the control E3/E3 brain (n⫽5) when compared to the diseased E4/E4 brain (n⫽5). This trend reached statistical significance in all three brain regions examined (p⬍0.05). Analysis of diseased E3/E3 brains (n⫽3) has so far revealed a non-significant trend for greater fragmentation than diseased E4/E4 but less than control E3/E3. Examination of the brain samples under non-reducing conditions revealed that a substantial proportion of apoE is present as a homo-dimer in E3/E3 brains regardless of the disease status. This was not observed in E4/E4 brains as E4 lacks a cysteine residue and thus is unable to form disulphide linked bonds. The contribution of postmortem delay and contamination by serum and cerebro spinal fluid seems an unlikely cause for this phenomenon as the homo-dimer was also observed in fresh rabbit brain and a neuronal cell line. Conclusions: ApoE fragmentation in the brain is most strongly correlated with the E3 isoform and the absence of AD. ApoE E3 exists in the brain as a homo-dimer, thus representing a major difference between E3 and E4 in the conformation, and possibly function, of brain apoE. P3-295
THE EFFECT OF APOLIPOPROTEIN E GENOTYPE ON NEUROGENESIS IN THE DENTATE GYRUS OF ADULT AND AGED MICE
Karen J. Horsburgh, Chantal Mutsaers, Jessica Smith, Jill H. Fowler, University of Edinburgh, Edinburgh, United Kingdom. Contact e-mail: [email protected]
Poster Presentations P3:
tion of A in the CA1 neurons correlates spatially and temporarily (t 1/2⬃ 1 week) with the accumulation of intraneuronal apoE in these neurons. Furthermore, these effects are associated with the loss of CA1 neurons synapses and with the occurrence of pronounced learning and memory deficits. Conclusions: These findings provide the first in vivo evidence regarding the cellular mechanisms underlying the pathological cross talk between apoE4 and A, as well as a novel model system of neurodegeneration in vivo that is uniquely suitable for studying the early stages of the amyloid cascade and the effects thereon of apoE4. P3-292
ASSOCIATION OF APOLIPOPROTEIN E AND SERUM ABETA LEVELS IN MEN UNDERGOING INTERMITTENT ANDROGEN ABLATION
Monique Cherrier, Patti Green, Gerald Schellenberg, Celestia Higano, University of Washington, Seattle, WA, USA. Contact e-mail: [email protected] Background: Declines in serum testosterone levels from aging is a risk factor for Alzheimer’s disease (AD). It has been suggested that increased risk for AD may be conferred through androgen regulation of beta-amyloid (abeta) accumulation which is believed to be a critical step in the cascade of AD pathogenesis. Recent evidence has shown that androgens regulate abeta in neuronal cell cultures and in a transgenic mouse model of AD. Methods: In the present study, we examined serum levels of abeta 1-40, 42 in men undergoing intermittent androgen deprivation therapy (ADT) for prostate cancer. Twenty hormone naı¨ve, eugonadal prostate cancer patients without evidence of metastases and with a rising PSA were treated with intermittent ADT consisting of nine months of leuprolide and flutamide followed by an “off treatment” period. Cognitive function tests were administered at baseline, after three and nine months of ADT and after three months of no treatment and blood samples were taken at these sessions. Results: As expected, serum levels of testosterone (T) were reduced significantly to castrate levels (p⬍.01) and estradiol levels were reduced approximately 50% (p⬍.05). ADT patients evidenced a significant decline in spatial reasoning, spatial abilities and working memory during treatment compared to baseline. Serum abeta 1-40, 42 levels were reduced significantly over time (p⬍.01) with an increase in the abeta42/40 ratio. However, when ADT patients were divided according to APOE status (apolipoprotein ⑀4 allele (APOE*4/4 and APOE*3/4 ⫽ APOE positive; all else ⫽ APOE negative) serum abeta 1-40, 42 levels increased only in the APOE*4 positive group and not in the APOE negative group and serum abeta 42/40 ratio decreased. Conclusions: These findings suggest that in humans, androgen regulation of abeta may be further modulated by the apolipoprotein ⑀4 allele. This is consistent with findings of T mediated modulation of cognitive impairments in the transgenic human APOE mouse model. P3-293
INTERACTION BETWEEN AMYLOID-BETA PEPTIDES WITH BUTYRYLCHOLINESTERASE AND APOE PROTEINS: MECHANISM OF AMYLOID FIBRILS DEPOSITION IN THE BRAIN OF PATIENTS WITH ALZHEIMER’S DISEASE
Taher Darreh-Shori1, Anton Forsberg1, Niels Andreasen1, Kaj Blennow2, Anders Wall3, Chelenk Kamil1, Bengt Långstro¨m3, Agneta Nordberg1, 1Karolinska Institutet, Stockholm, Sweden; 2 Gotenberg University, Gotenberg, Sweden; 3Imanet Uppsala, Uppsala, Sweden. Contact e-mail: [email protected] Background: We have previously shown that high age, ApoE4 and female gender (three AD risk factors) confer differential levels of circulating BuChE protein in CSF of AD patients. We hypothesize that CSF BuChE is inversely related to its deposition in amyloid plaques in the AD brain so that low level of BuChE in CSF may be predictive of higher degree of neurodegeneration due to an extensive incorporation of BuChE in neuritic plaques and the consequential increased neurotoxicity of plaques. Methods: BuChE and ApoE levels in plasma and CSF
of ninety mild AD patients were measured. Cerebral glucose utilization (CMRglc) was assessed by FDG-PET in 44 of the patients, whereas cerebral amyloid by PIB-PET in 26 patients. Results: The AD risk factors conferred differential level of ApoE protein in CSF of the patients. The CSF level of ApoE was increased with age (r⫽0.30, p⬍0.0006). Women and the carriers of ApoE e4 allele (in a gene-dose manner) had 40-45% higher level of ApoE protein in their CSF (p⬍0.01-0.002). These findings are similar to what we previously reported for the BuChE in CSF but in the opposite direction. Indeed, the CSF ApoE level showed a strong negative correlation with the BuChE level (r⫽0.47, p⬍0.0001). We also found that patients with high CSF BuChE had also a high soluble APP (r⫽0.59, p⬍0.006) and A-beta40 (r⫽0.45, p⬍0.05) in CSF. Preliminary functional assay of the BuChE suggested that the specific activity of BuChE was decreased in the CSF in an ApoE protein concentration-dependent manner. Remarkably, a high ratio of BuChE/ApoE protein was associated with a low amyloid load (PIB retention, r⫽ - 0.49, p⬍0.006) and a high rate of the cerebral glucose utilization (r⫽0.38, p⬍0.01) in the majority of cortical brain regions of the patients. Conclusions: These observations strongly support our hypothesis and suggest that high levels of ApoE protein in the brain may facilitate an extensive incorporation of BuChE in the A-beta deposits and conversion of benign plaques into the neuritic plaques. Further analysis are however needed to understand in details the proposed molecular interactions between ApoE, BuChE and A-beta fibrils in AD patients. P3-294
POST-TRANSLATIONAL MODIFICATIONS OF APOLIPOPROTEIN-E IN THE HUMAN BRAIN
David A. Elliott, Woojin S. Kim, Glenda M. Halliday, Brett Garner, Prince of Wales Medical Research Inst, Randwick, Australia. Contact e-mail: [email protected] Background: Polymorphism of apolipoprotein-E (apoE) is the greatest genetic risk factor for developing Alzheimer’s Disease (AD). We have investigated the influence of polymorphism and disease status on apoE post-translational modification in the human brain. Methods: Human brain homogenate samples were prepared from hippocampal, frontal and occipital regions obtained from AD and control donors of known apoE genotype. ApoE was examined by western blot under either reducing or non-reducing conditions. ApoE was also examined in SKNSH neuronal cells and rabbit brain homogenate prepared immediately after death. Results: A greater percentage of apoE was present as fragmentation products in the control E3/E3 brain (n⫽5) when compared to the diseased E4/E4 brain (n⫽5). This trend reached statistical significance in all three brain regions examined (p⬍0.05). Analysis of diseased E3/E3 brains (n⫽3) has so far revealed a non-significant trend for greater fragmentation than diseased E4/E4 but less than control E3/E3. Examination of the brain samples under non-reducing conditions revealed that a substantial proportion of apoE is present as a homo-dimer in E3/E3 brains regardless of the disease status. This was not observed in E4/E4 brains as E4 lacks a cysteine residue and thus is unable to form disulphide linked bonds. The contribution of postmortem delay and contamination by serum and cerebro spinal fluid seems an unlikely cause for this phenomenon as the homo-dimer was also observed in fresh rabbit brain and a neuronal cell line. Conclusions: ApoE fragmentation in the brain is most strongly correlated with the E3 isoform and the absence of AD. ApoE E3 exists in the brain as a homo-dimer, thus representing a major difference between E3 and E4 in the conformation, and possibly function, of brain apoE. P3-295
THE EFFECT OF APOLIPOPROTEIN E GENOTYPE ON NEUROGENESIS IN THE DENTATE GYRUS OF ADULT AND AGED MICE
Karen J. Horsburgh, Chantal Mutsaers, Jessica Smith, Jill H. Fowler, University of Edinburgh, Edinburgh, United Kingdom. Contact e-mail: [email protected]