Mitochondrial dynamics in Huntington's disease.
Emerging evidence suggests a central and early role of mitochondrial dysfunction, including altered mitochondrial dynamics, in Huntington's disease (HD) pathogenesis. Processes such as mitochondrial fission, fusion, transport and mitophagy are vital for proper mitochondrial function and seem to be key mediators of neuronal vulnerability in HD. In this review, we summarize mechanistic insights into mitochondrial dynamics in HD, highlighting how mutant huntingtin (mHTT) impairs mitochondrial biogenesis and morphology, disrupts Drp1-dependent fission, compromises fusion, transport and organelle crosstalk with the endoplasmic reticulum, and disrupts mitochondrial quality control, ultimately leading to neuronal degeneration. Since these alterations correlate with bioenergetic deficits, calcium dysregulation and oxidative stress, we highlight how altered mitochondrial dynamics contribute to and possibly drive HD pathogenesis. Furthermore, we discuss how mitochondrial dynamics in HD can be altered based on cell type specificity, experimental model and disease stage.