Quantitative proteomic analysis of induced pluripotent stem cells derived from a human Huntington's disease patient

Abstract

HD (Huntington's disease) is a devastating neurodegenerative genetic disorder caused by abnormal expansion of CAG repeats in the HTT (huntingtin) gene. We have recently established two iPSC (induced pluripotent stem cell) lines derived from a HD patient carrying 72 CAG repeats (HD-iPSC). In order to understand the proteomic profiles of HD-iPSCs, we have performed comparative proteomic analysis among normal hESCs (human embryonic stem cells; H9), iPSCs (551-8) and HD-iPSCs at undifferentiated stages, and identified 26 up- and down-regulated proteins. Interestingly, these differentially expressed proteins are known to be involved in different biological processes, such as oxidative stress, programmed cell death and cellular oxygen-associated proteins. Among them, we found that oxidative stress-related proteins, such as SOD1 (superoxide dismutase 1) and Prx (peroxiredoxin) families are particularly affected in HD-iPSCs, implying that HD-iPSCs are highly susceptible to oxidative stress. We also found that BTF3 (basic transcription factor 3) is up-regulated in HD-iPSCs, which leads to the induction of ATM (ataxia telangiectasia mutated), followed by activation of the p53-mediated apoptotic pathway. In addition, we observed that the expression of cytoskeleton-associated proteins was significantly reduced in HD-iPSCs, implying that neuronal differentiation was also affected. Taken together, these results demonstrate that HD-iPSCs can provide a unique cellular disease model system to understand the pathogenesis and neurodegeneration mechanisms in HD, and the identified proteins from the present study may serve as potential targets for developing future HD therapeutics.

In Vivo Roles of a Patient-Derived Induced Pluripotent Stem Cell Line (HD72-iPSC) in the YAC128 Model of Huntington’s Disease

“…We recently reported the characteristics of a HD patient-derived iPSC carrying 72 CAG repeats (HD72-iPSC) (10, 11). In this study, we investigated the in vivo roles of HD72-iPSC in the YAC128 transgenic mice, carrying the entire 170-kb genomic locus of human HTT gene plus 25 kb of the 5’ flanking sequence and about 120 kb of 3’ flanking sequence, which is commonly used as a pre-clinical model in HD (12).…”

iPSC-based drug screening for Huntington׳s disease

“…ATP levels were lower in NSCs bearing a longer CAG expansion (38), which indicates impaired mitochondrial function, as mitochondria are the major power source inside cells that produce ATP. Furthermore, neurite outgrowth was impaired in neurons differentiated from HD patient derived iPSCs (26), a phenomenon resembling defects in neuronal maturation and axon outgrowth in HD. These examples represent endpoints suitable for HD screens in a high throughput format, which is especially valuable when screening thousands of potential therapeutic candidates.…”

Translational Prospects and Challenges in Human Induced Pluripotent Stem Cell Research in Drug Discovery

“…In general, mRNAs, proteins, hormones, cytokines, and metabolites are measured by mapping these biomarkers to the landscape of the hypothetical disease pathway. For example, high susceptibility to oxidative stress was confirmed by quantitative proteomic analysis in iPS cells derived from a Huntington’s disease patient [52]. SOD1 (superoxide dismutase 1) and Prx (peroxiredoxin) families which were particularly affected in patient-derived iPS cells are expected to be clinical biomarkers in assessing efficiency of drug therapy.…”