Project description:Mitochondrial fusion and fission accompany adaptive responses to stress and altered metabolic demands. Inner membrane fusion and cristae morphogenesis depends on Optic Atrophy 1 (Opa1), which is expressed in different isoforms and is cleaved from a membrane-bound, long to a soluble, short form. Here, we have analyzed the physiological role of Opa1 isoforms and Opa1 processing by generating mouse lines expressing only one cleavable Opa1 isoform or a non-cleavable variant thereof. Our results show that expression of a single cleavable or non-cleavable Opa1 isoform preserves embryonic development and the health of adult mice. Opa1 processing is dispensable under metabolic and thermal stress, but prolongs lifespan and protects against mitochondrial cardiomyopathy in OXPHOS-deficient Cox10-/- mice. Mechanistically, loss of Opa1 processing disturbs the balance between mitochondrial biogenesis and mitophagy, suppressing cardiac hypertrophic growth in Cox10-/- hearts. Our results highlight the critical regulatory role of Opa1 processing, mitochondrial dynamics and metabolism for cardiac hypertrophy.
Project description:To investigate the function of Opa1 in the regulation of adult neurogenesis, we created a conditional Opa1-knockout mouse line by cross-breeding Nestin-CreERT2;ROSA26YFP mice with Opa1-Flox mice. Using Tamoxifen, we induced Opa1 knockout on 8-weeks-old Nestin-CreERT2;ROSA26YFP;Opa1-Flox mice. We then sorted YFP-positive cells from the hippocampus using flow cytometry at 10 weeks. RNA was extracted from sorted cells and subjected to next generation sequencing.
Project description:To investigate the function of Opa1 in the regulation of adult neurogenesis, we created a conditional Opa1-knockout mouse line by cross-breeding Nestin-CreERT2;ROSA26YFP mice with Opa1-Flox mice.
Project description:Dysfunctions in mitochondria dynamics and metabolism are common pathological processes associated with Parkinson’s disease (PD). Recently, it was shown that an inherited form of PD and dementia is caused by new mutations in the OPA1 gene, which encodes for a key player of mitochondrial fusion and structure. iPSC-derived neural cells from these patients exhibited severe mitochondrial fragmentation, respiration impairment, ATP deficits and heightened oxidative stress. Reconstitution of normal levels of OPA1 in PD-derived neural cells normalized mitochondria morphology and function. OPA1 mutated neuronal cultures showed reduced survival in vitro. Intriguingly, selective inhibition of necroptosis effectively rescued this survival deficit. Additionally, dampening necroptosis in MPTP treated mice protected from DA neuronal cell loss. This human iPSC-based model captures both the early pathological events in OPA1 mutant neural cells and the beneficial effects of blocking necroptosis, highlighting this cell death process as a promising therapeutic target for PD.
Project description:OPA1 is a dynamin-related GTPase that plays a critial role in governing mitochondrial fusion, cristae structure, and energetics. Here we found that OPA1 functions as a postive regulator of a nonapoptotic form of cell death termed ferroptosis. Although we determined that the OPA1 GTPase activity is required to drive ferroptosis, the fusogenic activity of OPA1 is dispensable for ferroptosis execution. Mechanistically, our studies show that OPA1 promotes ferroptosis through distinct mechanisms involving the generation of mitochondrial reactive oxygen species and suppression of the integrated stress response.
