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Date of Award
Doctor of Philosophy (PhD)
Aging is a major risk factor in many forms of late-onset neurodegenerative disorders. The ability to capture age-related characteristics of human neurons in culture will be invaluable to study the biological processes that are underlying neuronal aging. There are barriers, however, to accessibility of individual-specific neurons to investigate the age-related changes in neurons. Therefore, an appropriate alternative model of human neuronal aging is required. Here, I show that using a recently demonstrated microRNA-based cellular reprogramming approach, human fibroblasts from postnatal to centenarian donors can be efficiently converted to functionally mature neurons. I show that these neurons interestingly maintain multiple age-associated signatures. First, applying the epigenetic clock, which is an epigenetic biomarker of aging, to DNA methylation data reveals that the epigenetic ages of reprogrammed neurons were highly correlated with the age estimates of the corresponding starting fibroblast samples. Additionally, transcriptome and microRNA profiles of reprogrammed neurons confirm the presence of genes that are differentially expressed between young and old neurons, indicating the preservation of these age-related signatures. I also further investigated the levels of oxidative stress, DNA damage, and lengths of telomeres which all exhibited retention of age-associated cellular properties in converted neurons from corresponding fibroblasts. These results demonstrate the maintenance of age in reprogrammed neurons after direct conversion, highlighting the potential utility to study age-related neurodegenerative diseases. I further investigate the neurogenic potential of miR-9/9*-124 to not only convert fibroblasts to neurons, but also directly convert somatic cells of multiple cellular origins. This investigation reveals that miR-9/9*-124-mediated reprogramming can be universally applicable for neuronal conversion of multiple cell types, potentially by regulating genetic networks to promote neuronal fate acquisition and maintenance.
Chair and Committee
Andrew S. Yoo
Tim Schedl, Joseph Corbo, Kristen Kroll, Shin Imai
Huh, Christine Jean, "The Maintenance of Age in Reprogrammed Human Neurons" (2016). Arts & Sciences Electronic Theses and Dissertations. 994.
Available for download on Tuesday, December 15, 2116