Loss of OPA1 disturbs cellular calcium homeostasis and sensitizes for excitotoxicity
Abbreviated Journal Title
Cell Death Differ.
calcium; mitochondria; OPA1; DOMINANT OPTIC ATROPHY; MITOCHONDRIAL INNER-MEMBRANE; DYNAMIN-RELATED; GTPASE; RETINAL GANGLION-CELLS; ACUTE GLUTAMATE EXCITOTOXICITY; CYTOCHROME-C RELEASE; CEREBELLAR GRANULE CELLS; ATP PRODUCTION; APOPTOSIS; CRISTAE; Biochemistry & Molecular Biology; Cell Biology
Optic atrophy 1 (OPA1) mutations cause dominant optic atrophy (DOA) with retinal ganglion cell (RGC) and optic nerve degeneration. The mechanism for the selective degeneration of RGCs in DOA remains elusive. To address the mechanism, we reduced OPA1 protein expression in cell lines and RGCs by RNA interference. OPA1 loss results in mitochondrial fragmentation, deficiency in oxidative phosphorylation, decreased ATP levels, decreased mitochondrial Ca2+ retention capacity, reduced mtDNA copy numbers, and sensitization to apoptotic insults. We demonstrate profound cristae depletion and loss of crista junctions in OPA1 knockdown cells, whereas the remaining crista junctions preserve their normal size. OPA1-depleted cells exhibit decreased agonist-evoked mitochondrial Ca2+ transients and corresponding reduction of NAD(+) to NADH, but the impairment in NADH oxidation leads to an overall more reduced mitochondrial NADH pool. Although in our model OPA1 loss in RGCs has no apparent impact on mitochondrial morphology, it decreases buffering of cytosolic Ca2+ and sensitizes RGCs to excitotoxic injury. Exposure to glutamate triggers delayed calcium deregulation (DCD), often in a reversible manner, indicating partial resistance of RGCs to this injury. However, when OPA1 is depleted, DCD becomes irreversible. Thus, our data show that whereas OPA1 is required for mitochondrial fusion, maintenance of crista morphology and oxidative phosphorylation, loss of OPA1 also results in defective Ca2+ homeostasis. Cell Death and Differentiation (2013) 20, 353-365; doi:10.1038/cdd.2012.128; published online 9 November 2012
Cell Death and Differentiation
"Loss of OPA1 disturbs cellular calcium homeostasis and sensitizes for excitotoxicity" (2013). Faculty Bibliography 2010s. 4248.