Emerin organizes actin flow for nuclear movement and centrosome orientation in migrating fibroblasts

Abstract

Emerin, a nuclear membrane protein, and myosin IIB contribute to nuclear movement by regulating the directionality of nuclear movement and dorsal actin cable flow. Emerin interacts with myosin IIB and is required for its perinuclear localization. The results show that the nuclear envelope actively organizes cytoplasmic polarity.

The nucleus is an intracellular propagator of tensile forces in NIH 3T3 fibroblasts

“…Similarly, we observed no significant deformation but some translocation in KASH4-expressing cells, suggesting that there is a requirement of nuclear-cytoskeletal linkage for mechanical coupling of the membrane to the nucleus. These linkages might be due to nuclear proteins like nesprin 2G (Chang et al, 2013) Because the nucleus is thought to potentially be compressed by lateral stress fibers in slender portions of the migrating cell (Versaevel et al, 2012), one hypothesis is also that local protrusion pulls out lateral fibers that then allows the nucleus to expand. Our results, however, indicate that nuclear deformation is not necessarily accompanied by stress fiber motion in the direction of the protrusion and that severing individual fibers touching the nucleus or in close physical proximity of it does not cause expansion of the nucleus; these results argue against the lateral compression hypothesis.…”

Nuclear migration events throughout development

“…At the nucleoplasmic side of TAN lines, lamin A (Lmna) and emerin (Emd) are required to anchor nuclei to TAN lines but are not involved in TAN line formation. Although mutations in lamin A or emerin result in non-moving nuclei, TAN lines still glide along the surface of the nuclear envelope (Chang et al, 2013a;Folker et al, 2011). The inner nuclear membrane protein spindle-associated membrane protein 1 (Samp1; also known as NET5 and officially known as TMEM201) is an additional component of TAN lines and functions, in part, to connect Sun2 to lamin A (Borrego-Pinto et al, 2012).…”

The contractome – a systems view of actomyosin contractility in non-muscle cells

“…The nucleus, which is the target of many signaling events, is also sensitive to contractility forces that affect its architecture, stiffness, localization within the cell and its activity, for instance with regard to chromatin remodeling, DNA synthesis and gene expression (Chang et al, 2013;Goulding et al, 2007;Guilluy et al, 2014;Hossain et al, 2006;Kim et al, 2005;Kiss et al, 2014;Maeda et al, 2013;SarasaRenedo et al, 2006;Song et al, 2002;Szabo et al, 2011). With these key regulatory roles, it is not surprising that contractility has been shown to affect cell proliferation and differentiation in several experimental systems (Chowdhury et al, 2010;Ozdemir et al, 2013;Rottmar et al, 2014).…”