Semi autonomous nature of mitochondria

Actin plays many well-known roles in cells, and understanding any specific role is often confounded by the overlap of multiple actin-based structures in space and time. Here, we review our rapidly expanding understanding of actin in mitochondrial biology, where actin plays multiple distinct roles, exemplifying the versatility of actin and its functions in cell biology. One well-studied role of actin in mitochondrial biology is its role in mitochondrial fission, where actin polymerization from the endoplasmic reticulum through the formin INF2 has been shown to stimulate two distinct steps. However, roles for actin during other types of mitochondrial fission, dependent on the Arp2/3 complex, have also been described. In addition, actin performs functions independent of mitochondrial fission. During mitochondrial dysfunction, two distinct phases of Arp2/3 complex-mediated actin polymerization can be triggered. First, within 5 min of dysfunction, rapid actin assembly around mitochondria serves to suppress mitochondrial shape changes and to stimulate glycolysis. At a later time point, at more than 1 h post-dysfunction, a second round of actin polymerization prepares mitochondria for mitophagy. Finally, actin can both stimulate and inhibit mitochondrial motility depending on the context. These motility effects can either be through the polymerization of actin itself or through myosin-based processes, with myosin 19 being an important mitochondrially attached myosin. Overall, dis...

• Live cell imaging studies showed that mitochondria are highly dynamic organelles that frequently fuse and divide. • Two evolutionarily conserved large GTPases constitute the core machinery of fusion: mitofusins are found in the outer membrane, and Mgm1 and optic atrophy protein 1 (OPA1) are found in the inner membrane of yeast and mammals, respectively. • Mitochondrial fission is mediated by dynamin-related proteins (DRPs) and cofactors that are required for assembly of DRP rings and spirals on the mitochondrial surface. Only little is known about division of the inner membrane. • The machineries of mitochondrial fusion and fission are regulated by many cellular pathways, including proteolytic processing, ubiquitylation, sumoylation, phosphorylation and dephosphorylation. • Mitochondrial fusion and fission are required for faithful inheritance and proper intracellular distribution of the organelle. • Mitochondrial dynamics counteracts cellular ageing by allowing complementation of gene products after fusion of impaired mitochondria, and it constitutes an important part of organellar quality control as it facilitates the elimination of damaged mitochondria by autophagy. Furthermore, mitochondrial division is an important step in apoptosis. • Dysfunctions of mitochondrial dynamics contribute to several inherited and age-associated neurodegenerative diseases. Mitochondria are dynamic organelles that constantly fuse and divide. These processes (collectively termed mitochondr...

Much of our current knowledge about mitochondria has come from studying patients who have respiratory chain disorders. These disorders comprise a large collection of individually rare syndromes, each presenting in a unique and often devastating way. In recent years, there has been great progress in defining their genetic basis, but we still know little about the cascade of events that gives rise to such diverse pathology. Here, we review these disorders and explore them in the context of a contemporary understanding of mitochondrial evolution, biochemistry and genetics. Fully deciphering their pathogenesis is a challenging next step that will inspire the development of drug treatments for rare and common diseases. Open Access articles citing this article. • • Fumika Nanto-Hara • , Makoto Yamazaki • … Haruhiko Ohtsu Journal of Animal Science and Biotechnology Open Access 03 June 2023 • • Ricardo Sánchez-Rodríguez • , Caterina Tezze • … Barbara Molon Cell Death & Differentiation Open Access 28 October 2022 • • Yifei Chen • , Fuji Yang • … Jianhua Jin Journal of Translational Medicine Open Access 22 October 2022 Access options • Ernster, L., Ikkos, D. & Luft, R. Enzymic activities of human skeletal muscle mitochondria: a tool in clinical metabolic research. Nature 184, 1851–1854 (1959). This paper reports a fascinating case of euthyroid hypermetabolism, which is now regarded as the first case of a biochemically proven mitochondrial disease. • DiMauro, S. et al. Luft's disease...

An organelle being fully autonomous would mean that it is fully self-sustainable - requiring no assistance from the cell to function and reproduce. The mitochondria is semi-autonomous because it is, in large, self-sustainable. The mitochondria has its own DNA (circular), Rhibosomes and the ability to make its own proteins. The reason then, that it is not fully autonomous, is simply that is does not have contact with the external environment - this means that the mitochondria is dependent on its surroundings, to give to it, molecules for metabolism (via endocytosis and other membrane transport mechanisms). So if you think about it in respect to evolution, the mitochondria once was a fully independent (autonomous) bacterium. Once engulfed by a eukaryotic cell, it was embraced due to its high E producing ability and in turn, the bacterium became part of the eukaryote cell and is now dependant on the cell but only to supply it with metabolites. In short: It hasn't the ability to obtain and breakdown its own biomolecules D students answer: "In can do everything on its own except get its own food" What are the semi autonomous organelles in a cell? these are the mitochondria and chloroplasts and it is because they have their own DNA, mRNA, tRNA, ribosomes and they replicate by binary fission so they are said to be self governing. Semi autonomous means they want to leave but they are in a symbiotic relationship with the cell and have evolved to become part of it. Name three charac...

Mitochondrial biogenesis is indispensable for organismal homeostasis. The semi-autonomous nature of mitochondria renders their biogenesis rather complex, as it requires the contribution of the nucleus, the cytoplasm and the organelle itself. Recently, several transcription regulators, RNA binding proteins and outer mitochondrial membrane (OMM) components have been implicated in the coordination of the process. Both the expression and the abundance of several of these factors are altered during ageing, and their impairment can have diverse, yet principally detrimental, effects on lifespan. These findings converge on the notion that mitochondrial biogenesis is an age-modulated process that, when perturbed, compromises survival. Notably, core brain functions are dependent on mitochondrial metabolite availability. Indeed, emerging evidence indicates that mitochondrial biogenesis regulators play important roles in the onset and progression of severe neurodegenerative syndromes such as AD, PD and HD. These devastating human pathologies remain incurable to date. A better understanding of the mechanisms that govern mitochondrial biogenesis could facilitate the development of effective pharmaceutical interventions against these diseases. Introduction Mitochondria serve pivotal roles in the regulation of cellular homeostasis by controlling energy metabolism. In addition, they are tightly associated with the regulation of ion homeostasis, intermediate metabolism, apoptosis, lipid met...