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Dynamic constriction and fission of endoplasmic reticulum membranes by reticulon.

Nature communications (2019-11-24)
Javier Espadas, Diana Pendin, Rebeca Bocanegra, Artur Escalada, Giulia Misticoni, Tatiana Trevisan, Ariana Velasco Del Olmo, Aldo Montagna, Sergio Bova, Borja Ibarra, Peter I Kuzmin, Pavel V Bashkirov, Anna V Shnyrova, Vadim A Frolov, Andrea Daga
ABSTRACT

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.

MATERIALS
Product Number
Brand
Product Description

Avanti
18:1 PS (DOPS), 1,2-dioleoyl-sn-glycero-3-phospho-L-serine (sodium salt), chloroform
Sigma-Aldrich
L-α-Phosphatidylethanolamine, dioleoyl, ≥99% (GC), ≥98% (TLC), lyophilized powder
CellCrown inserts, 6 well plate inserts with 1.0 μm polycarbonate filter, sterile