mitochondriaux

Mitochondriaux is the French adjective meaning mitochondrial or relating to mitochondria. In English-language texts the corresponding term is mitochondrial. This article provides a concise overview of mitochondria and processes typically described as mitochondriaux.

Mitochondria are double-membrane organelles with an outer membrane and an inner membrane that folds into cristae. The matrix contains enzymes of the TCA cycle. They house their own circular DNA (mtDNA) and ribosomes, but most mitochondrial proteins are encoded in the nucleus and imported through translocases.

Their core function is ATP production via oxidative phosphorylation in the inner membrane, driven by a proton gradient established by the electron transport chain. The TCA cycle operates in the matrix to supply reducing equivalents. Mitochondria also regulate calcium signaling, participate in heme and iron-sulfur cluster biosynthesis, and can initiate apoptosis in response to cellular stress. In brown adipose tissue, the protein UCP1 can uncouple respiration to generate heat.

Mitochondria continually undergo fusion and fission, balancing maintenance and distribution within cells. Quality control includes mitophagy, a selective autophagy pathway that removes damaged mitochondria. Protein and lipid trafficking, as well as mitochondrial biogenesis, coordinate with cellular energy demands.

Origin and genetics: mitochondria are widely believed to descend from an ancestral alpha-proteobacterium through endosymbiosis. In humans, mtDNA is a small circular genome inherited maternally; many mitochondrial proteins are encoded in the nucleus. Heteroplasmy and mutation rates influence disease risk and expression.

Clinical relevance: mutations in mtDNA or in nuclear genes essential for mitochondrial function cause a range of mitochondrial diseases, including LHON and MELAS, as well as various complex I deficiencies. Mitochondrial dysfunction also features in aging and several neurodegenerative disorders. Research explores metabolism, organelle dynamics, and therapeutic approaches.