Emerin caps the pointed end of actin filaments: evidence for an actin cortical network at the nuclear inner membrane

• Published in: PLoS biology Vol. 2; no. 9; p. E231
• Main Authors: Holaska, James M, Kowalski, Amy K, Wilson, Katherine L
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 01.09.2004; Public Library of Science (PLoS)
• Subjects: Actin Cytoskeleton - chemistry; Actins - chemistry; Binding Sites; Cell Biology; Cell culture; Cell Membrane - metabolism; Cell Nucleus - metabolism; Chromatography, Affinity; Cytoskeleton; Disease; Gelsolin - chemistry; HeLa Cells; Homo (Human); Humans; Membrane Proteins - chemistry; Muscular Dystrophies - pathology; Nuclear Envelope - metabolism; Nuclear Proteins; Protein Binding; Proteins; Thymopoietins - chemistry; Transcription, Genetic; Thymopoietins; Actin Cytoskeleton; Cell Membrane; Humans; Actins; Nuclear Envelope; Nuclear Proteins; Membrane Proteins; Chromatography, Affinity; Muscular Dystrophies; Protein Binding; Transcription, Genetic; Gelsolin; HeLa Cells; Binding Sites; Cell Nucleus
• ISSN: 1545-7885; 1544-9173; 1545-7885
• DOI: 10.1371/journal.pbio.0020231

X-linked Emery-Dreifuss muscular dystrophy is caused by loss of emerin, a LEM-domain protein of the nuclear inner membrane. To better understand emerin function, we used affinity chromatography to purify emerin-binding proteins from nuclear extracts of HeLa cells. Complexes that included actin, alphaII-spectrin and additional proteins, bound specifically to emerin. Actin polymerization assays in the presence or absence of gelsolin or capping protein showed that emerin binds and stabilizes the pointed end of actin filaments, increasing the actin polymerization rate 4- to 12-fold. We propose that emerin contributes to the formation of an actin-based cortical network at the nuclear inner membrane, conceptually analogous to the actin cortical network at the plasma membrane. Thus, in addition to disrupting transcription factors that bind emerin, loss of emerin may destabilize nuclear envelope architecture by weakening a nuclear actin network.