Nuclear myosin I regulates cell membrane tension.

Tomáš Venit,Martin Petr,Alžběta Kalendová,Lukáš Pastorek,Rastislav Dzijak,Jana Rohožková,Jakub Malohlava,Pavel Hozák

doi:10.1038/srep30864

Abstract

Plasma membrane tension is an important feature that determines the cell shape and influences processes such as cell motility, spreading, endocytosis and exocytosis. Unconventional class 1 myosins are potent regulators of plasma membrane tension because they physically link the plasma membrane with adjacent cytoskeleton. We identified nuclear myosin 1 (NM1) - a putative nuclear isoform of myosin 1c (Myo1c) - as a new player in the field. Although having specific nuclear functions, NM1 localizes predominantly to the plasma membrane. Deletion of NM1 causes more than a 50% increase in the elasticity of the plasma membrane around the actin cytoskeleton as measured by atomic force microscopy. This higher elasticity of NM1 knock-out cells leads to 25% higher resistance to short-term hypotonic environment and rapid cell swelling. In contrast, overexpression of NM1 in wild type cells leads to an additional 30% reduction of their survival. We have shown that NM1 has a direct functional role in the cytoplasm as a dynamic linker between the cell membrane and the underlying cytoskeleton, regulating the degree of effective plasma membrane tension.

Highlights

Plasma membrane tension is an important feature that determines the cell shape and influences processes such as cell motility, spreading, endocytosis and exocytosis
By using the antibody specific for the N-terminal peptide of nuclear myosin 1 (NM1) and the antibody against the tail domain, we have shown that both proteins are predominantly localized in the cytoplasm, as shown by densitometric analysis of the immunoblotting (Fig. 1C.)
Our results revealed that both, wild-type NM1 and myosin 1c (Myo1c) localize to the cytoplasm and are enriched at the plasma membrane

Summary

Introduction

Plasma membrane tension is an important feature that determines the cell shape and influences processes such as cell motility, spreading, endocytosis and exocytosis. Deletion of NM1 causes more than a 50% increase in the elasticity of the plasma membrane around the actin cytoskeleton as measured by atomic force microscopy This higher elasticity of NM1 knock-out cells leads to 25% higher resistance to short-term hypotonic environment and rapid cell swelling. Myosin 1C belongs to the group of class 1 myosins (named A-H), which are monomeric molecules with relatively short tails through which they interact with cargos and other proteins In humans, it is transcribed from the MYO1C gene, which gives rise to two additional mRNAs differing at the 5′UTRs and translation start sites. All vertebrate class 1 myosins share the same features: they bind actin with their head domain and acidic phospholipids with the pleckstrin homology domain (PH), which is localized in their tail part[3,4,5] This implicates their physiological functions – linking membranes and membrane-coated vesicles to actin-rich structures, such as cytoskeleton. We asked whether NM1 could functionally replace Myo1c in the cytoplasm of cells

Methods

Results

Conclusion