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Mitochondrial fission

)]] Although commonly depicted singular oval-shaped structures, mitochondria form a highly dynamic network within most cells where they constantly undergo fission and fusion. Mitochondria can divide by prokaryotic binary fission and since they require mitochondrial DNA for their function, fission is coordinated with DNA replication. Some of the proteins that are involved in mitochondrial fission have been identified and some of them are associated with mitochondrial diseases.{{Cite journal | last1 = Otera | first1 = H. | last2 = Mihara | first2 = K. | doi = 10.4161/sgtp.2.3.16486 | title = Discovery of the membrane receptor for mitochondrial fission GTPase Drp1 | journal = Small GTPases | volume = 2 | issue = 3 | pages = 167–172 | year = 2011 | pmid = 21776419 | pmc =3136948 }} Mitochondrial fission has significant implications in stress response and apoptosis.

Mechanism

The Drp1 protein is a member of the dynamin family of large GTPases. Drp1 controls the final part of mitochondrial fission, pinching off the membrane stalk between two forming daughter mitochondria. The MFN2 protein is part of a complex that links the endoplasmic reticulum (ER) to mitochondria. Points of ER-mitochondrial association have been associated with the formation of Drp1 complexes and mitochondrial fission.{{Cite journal | last1 = Friedman | first1 = J. R. | last2 = Lackner | first2 = L. L. | last3 = West | first3 = M. | last4 = Dibenedetto | first4 = J. R. | last5 = Nunnari | first5 = J. | last6 = Voeltz | first6 = G. K. | title = ER Tubules Mark Sites of Mitochondrial Division | doi = 10.1126/science.1207385 | journal = Science | year = 2011 | pmid = 21885730 | pmc = 3366560| volume=334 | issue=6054 | pages=358–62 }} Several Drp1-binding proteins have been identified.{{Cite journal | last1 = Dikov | first1 = D. | last2 = Reichert | first2 = A. S. | doi = 10.1038/emboj.2011.219 | title = How to split up: Lessons from mitochondria | journal = The EMBO Journal | volume = 30 | issue = 14 | pages = 2751–2753 | year = 2011 | pmid = 21772324 | pmc =3160261 }} A protein called mitochondrial fission factor (Mff) binds Drp1 and promotes mitochondrial fission.{{Cite journal | last1 = Otera | first1 = H. | last2 = Wang | first2 = C. | last3 = Cleland | first3 = M. M. | last4 = Setoguchi | first4 = K. | last5 = Yokota | first5 = S. | last6 = Youle | first6 = R. J. | last7 = Mihara | first7 = K. | doi = 10.1083/jcb.201007152 | title = Mff is an essential factor for mitochondrial recruitment of Drp1 during mitochondrial fission in mammalian cells | journal = The Journal of Cell Biology | volume = 191 | issue = 6 | pages = 1141–1158 | year = 2010 | pmid = 21149567 | pmc =3002033 }} The FIS1 protein might recruit Drp1 to sites of fission{{Cite journal | last1 = Huang | first1 = P. | last2 = Galloway | first2 = C. A. | last3 = Yoon | first3 = Y. | editor1-last = Jackson | editor1-first = Catherine L. | title = Control of Mitochondrial Morphology Through Differential Interactions of Mitochondrial Fusion and Fission Proteins | doi = 10.1371/journal.pone.0020655 | journal = PLoS ONE | volume = 6 | issue = 5 | pages = e20655 | year = 2011 | pmid = 21647385 | pmc =3103587 }} but it might require association with another protein, MIEF1 (mitochondrial elongation factor 1) coded for by the SMCR7L gene, to promote mitochondrial fission. In contrast, MIEF1 when bound to Drp1 might prevent mitochondrial fission and thus shift the balance towards fusion of mitochondria.{{Cite journal | last1 = Zhao | first1 = J. | last2 = Liu | first2 = T. | last3 = Jin | first3 = S. | last4 = Wang | first4 = X. | last5 = Qu | first5 = M. | last6 = Uhlén | first6 = P. | last7 = Tomilin | first7 = N. | last8 = Shupliakov | first8 = O. | last9 = Lendahl | first9 = U. | doi = 10.1038/emboj.2011.198 | last10 = Nistér | first10 = M. | title = Human MIEF1 recruits Drp1 to mitochondrial outer membranes and promotes mitochondrial fusion rather than fission | journal = The EMBO Journal | volume = 30 | issue = 14 | pages = 2762–2778 | year = 2011 | pmid = 21701560 | pmc =3160255 }} Recent research found that actin polymerization through ER-localized inverted formin 2 (INF2) was required for efficient mitochondrial fission in mammalian cells. INF2 functioned upstream of Drp1. INF2-induced actin filaments may drive initial mitochondrial constriction, which allows Drp1-driven secondary constriction. Cryo-electron tomography has been able to visualize mitochondrial division in frozen hydrated cells and has led to the suggestion that mitochondria divide by budding.

See also

References

"green air" © 2007 - Ingo Malchow, Webdesign Neustrelitz
This article based upon the http://en.wikipedia.org/wiki/Mitochondrial_fission, the free encyclopaedia Wikipedia and is licensed under the GNU Free Documentation License.
Further informations available on the list of authors and history: http://en.wikipedia.org/w/index.php?title=Mitochondrial_fission&action=history
presented by: Ingo Malchow, Mirower Bogen 22, 17235 Neustrelitz, Germany