O1–01–05: Human iPSC‐derived neurons reveal novel effects of the APP London mutation and show cell fate‐specific Alzheimer's disease relevant phenotypes
Year: 2013
Type: article
Abstract: Alzheimer's disease (AD) is characterized by extracellular plaques containing amyloid β-protein (Aβ) and intracellular tangles containing hyperphosphorylated Tau protein. Distinct brain regions are differentially susceptible to neurodegeneration in AD, with the cortex and hippocampus being primarily affected and the cerebellum and spinal cord being relatively spared. While familial AD (fAD) comprises <1% of cases, analyses of these patients have advanced understanding of molecular mechanisms and therapeutic approaches for all AD cases. We describe the generation of inducible pluripotent stem cells (iPSCs) from humans harboring the London fAD APP mutation (V717I), and examine AD-relevant phenotypes following directed differentiation of these cells to rostral forebrain neuronal fates vulnerable in AD, as well as more caudal fates, which are relatively spared in AD. Immunostaining, qPCR, Nanostring analyses and Western blotting were used to examine expression of factors central to APP cleavage. In addition, ELISAs were utilized to measure the generation and secretion of APP cleavage products. In all fates examined, the APP V717I mutation led to elevated production of Aβ42 and Aβ38. Unexpectedly, this mutation, which lies near the γ -secretase cleavage site in the transmembrane domain of APP, also led to increased β-secretase cleavage of APP. This increase was abolished by inhibiting γ -secretase, suggesting that the two protease activities are functionally linked. Interestingly, directing cells to different neuronal fates resulted in altered cleavage patterns of APP. From both control and fAD lines, Aβ generated from neurons directed to forebrain cortical fates showed a higher Aβ42 to Aβ40 ratio relative to neurons directed to more caudal fates of the hindbrain and spinal cord. Moreover, consistent with fate-specific biochemical effects on Aβ, the APP V717I mutation led to increased Tau expression in forebrain cultures but not in more caudally directed neurons. These studies identify previously unappreciated effects of an fAD APP mutation in human neurons and demonstrate that human iPSC technology provides a powerful system for analyzing the effects of both genetic alterations and cell types on processes directly relevant to human brain diseases.
Source: Alzheimer s & Dementia
Institutions: Brigham and Women's Hospital, Harvard University
Language: English
Subfield: Physiology
Field: Medicine
Domain: Health Sciences
Open Access status: bronze
OpenAlex ID: W2122840348