Alzheimer Disease: George-Hyslop PS

Rogaeva E, Kawarai T, George-Hyslop PS. · Centre for Research in Neurodegenerative Diseases, Department of Medicine, University of Toronto, 6 Queen's Park Crescent West, Toronto, ON, Canada M5S 3H2. · J Alzheimers Dis. · Pubmed #16914876 No free full text.

Abstract: About 1% of Alzheimer's Disease (AD) cases have an early-onset autosomal dominant familial form of the disease, genetic analyses of which have found three causal genes: amyloid beta-protein precursor (AbetaPP), presenilin 1 (PS1) and presenilin 2 (PS2). The APOE gene is the only robustly replicated risk factor for the common form of AD with onset after 65 years of age. In at least half of the AD cases, there is no known cause of the disease. Here we provide an overview on known AD-linked genes and discuss the strategies of searching for novel AD genetic risk factors.

Shibata N, Kawarai T, Meng Y, Lee JH, Lee HS, Wakutani Y, Shibata E, Pathan N, Bi A, Sato C, Sorbi S, Bruni AC, Duara R, Mayeux R, Farrer LA, George-Hyslop PS, Rogaeva E. · Centre for Research in Neurodegenerative Diseases, Department of Medicine, University of Toronto and Toronto Western Hospital Research Institute, Toronto, Ontario, Canada. · Neurobiol Aging. · Pubmed #16828203 links to  free full text

Abstract: The plasmin system is involved in the degradation of Abeta peptides, the accumulation of which in brain is a hallmark of Alzheimer's disease (AD). In a North European case-control AD dataset we studied 14 common variations in the PLG, PAI-1, PLAT and PLI genes encoding components of the plasmin system. Among the four polymorphisms in the PLAT, PAI-1 and PLI genes showing nominally significant evidence for an association with AD (allele p-value=0.01-0.00003) the strongest association was detected for the deletion allele in the Alu-repeat region of the PLAT gene. However, none of these positive results were confirmed in follow-up studies using an independent Canadian case-control cohort and two familial AD datasets of North European and Caribbean Hispanic origin. Thus, the current survey does not support the notion that common polymorphisms in the plasmin genes influence the development of AD.

George-Hyslop PS, Rossor M. · Department of Medicine, Centre for Research in Neurodegenerative Diseases, University of Toronto, ON M5S 3H2, Toronto, Canada. · Lancet. · Pubmed #11784550 No free full text.

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Katayama T, Imaizumi K, Honda A, Yoneda T, Kudo T, Takeda M, Mori K, Rozmahel R, Fraser P, George-Hyslop PS, Tohyama M. · Department of Anatomy and Neuroscience, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan. · J Biol Chem. · Pubmed #11551913 links to  free full text

Abstract: Recent studies have shown independently that presenilin-1 (PS1) null mutants and familial Alzheimer's disease (FAD)-linked mutants should both down-regulate signaling of the unfolded protein response (UPR). However, it is difficult to accept that both mutants possess the same effects on the UPR. Furthermore, contrary to these observations, neither loss of PS1 and PS2 function nor expression of FAD-linked PS1 mutants were reported to have a discernable impact on the UPR. Therefore, re-examination and detailed analyses are needed to clarify the relationship between PS1 function and UPR signaling. Here, we report that PS1/PS2 null and dominant negative PS1 mutants, which are mutated at aspartate residue 257 or 385, did not affect signaling of the UPR. In contrast, FAD-linked PS1 mutants were confirmed to disturb UPR signaling by inhibiting activation of both Ire1alpha and ATF6, both of which are endoplasmic reticulum (ER) stress transducers in the UPR. Furthermore, PS1 mutants also disturbed activation of PERK (PKR-like ER kinase), which plays a crucial role in inhibiting translation during ER stress. Taken together, these observations suggested that PS1 mutations could affect signaling pathways controlled by each of the respective ER-stress transducers, possibly through a gain-of-function.

Jaikaran ET, Marcon G, Levesque L, George-Hyslop PS, Fraser PE, Clark A. · Diabetes Research Laboratories and Department of Human Anatomy and Genetics, Oxford, UK. · J Cell Sci. · Pubmed #10362543 links to  free full text

Abstract: Mutations in presenilin 1 and 2 are causative factors for early onset familial Alzheimer's disease and possible roles for presenilins include protein trafficking, regulation of apoptosis and/or calcium homeostasis. Presenilin 2 mRNA is expressed in brain, muscle and pancreas but the role of pancreatic presenilin 2 and its relationship to diabetes are unknown. Presenilin 2 immunoreactivity was localised in human and rodent pancreas to islet cells and found in granules of beta-cells. Presenilin 2 was identified in primitive islet and duct cells of human foetal pancreas and in proliferating exocrine duct cells in human pancreatitis but not found in islet amyloid deposits in Type 2 diabetic subjects. Full length, approximately 50 kDa, and the approximately 30 kDa N-terminal fragment of presenilin 2 were identified by western blotting in extracted rodent pancreas but only the 30 kDa fragment was detected in mouse islets and human insulinoma. Post-mortem pancreatic morphology was normal in a subject with the presenilin 2 Met239Val variant and early onset familial Alzheimer's disease. Oral glucose tolerance tests on subjects with the presenilin 2 Met239Val mutation unaffected by early onset familial Alzheimer's disease (mean age 35 years) and on their first-degree relatives without the mutation demonstrated no evidence of glucose intolerance or increased proinsulin secretion. PS2 is a novel &bgr;-cell protein with potential roles in development or protein processing but pancreatic islet structure and function appear to be unaffected by the Met239Val mutation.