| Summary: | 碩士 === 國立陽明大學 === 藥理學研究所 === 105 === Leber’s hereditary optic neuropathy (LHON) is a maternally inherited mitochondrial disease caused by homoplasmic point mutations in Complex I subunit genes of mitochondrial DNA. LHON is characterized by incomplete penetrance, as only part of Complex I mutation carriers become affected. Therefore, the mitochondrial DNA mutation is necessary, but not sufficient to cause optic neuropathy. Multiple factors were considered for explaining its variable penetrance, such as environmental triggers and genetic modifying factors. However, the mechanism of low penetrance of Complex I mutation is still largely unclear. LHON patient-specific induced pluripotent stem cells (iPSCs) from affected patients and carriers provide a powerful in vitro model for evaluating the pathological phenotypes of the disease. First, we detected an identical homoplasmic 11778 G>A mutation in all individuals after RGCs differentiation to verify mitochondrial DNA mutation load would not affect by reprogramming and differentiation. To characterize the pathological phenotypes of LHON iPSC-RGCs, we compared the neurite outgrowth and mitochondrial function between control, affected and carriers. The common compensatory strategy to mitochondrial dysfunction observed in LHON iPSC-RGCs, a globally activated mitochondrial biogenesis associated with increased mitochondrial DNA content. The neurites morphology indicated affected individuals were defective in RGC neurogenesis and maintenance. We measured the mitochondrial Complex I enzyme activity and oxygen consumption, and showed that carriers have a significantly higher Complex I activity and affected have lower maximal respiratory capacity as compared to control. Furthermore, the whole genome profile and LHON-related pathways would be analyzed by microarray analysis in LHON carriers and patients. This study will provide a novel finding for the pathological mechanism of LHON.
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