Dynamic constriction and fission of endoplasmic reticulum membranes by reticulon
Through an in vitro analysis of the visco-elastic properties of membrane nanotubes containing purified reticulon, the authors show that reticulons link the topology and motility of the ER network, providing a novel means of controlling morphology of dynamic intracellular organelles.
Espadas J, Pendin D, Bocanegra R, Escalada A, Misticoni G, Trevisan T, Velasco Del Olmo A, Montagna A, Bova S, Ibarra B, Kuzmin PI, Bashkirov PV, Shnyrova AV, Frolov VA, Daga A.
Nat Commun 2019 Nov; 10: 5327.
The endoplasmic reticulum (ER) is a continuous cell-wide membrane network. Network formation has been associated with proteins producing membrane curvature and fusion, such as reticulons and atlastin. Regulated network fragmentation, occurring in different physiological contexts, is less understood. Here we find that the ER has an embedded fragmentation mechanism based upon the ability of reticulon to produce fission of elongating network branches. In Drosophila, Rtnl1-facilitated fission is counterbalanced by atlastin-driven fusion, with the prevalence of Rtnl1 leading to ER fragmentation. Ectopic expression of Drosophila reticulon in COS-7 cells reveals individual fission events in dynamic ER tubules. Consistently, in vitro analyses show that reticulon produces velocity-dependent constriction of lipid nanotubes leading to stochastic fission via a hemifission mechanism. Fission occurs at elongation rates and pulling force ranges intrinsic to the ER, thus suggesting a principle whereby the dynamic balance between fusion and fission controlling organelle morphology depends on membrane motility.
PubMed: 31757972. Doi: 10.1038/s41467-019-13327-7. OPEN Free PMC
