Holaska James M, Kowalski Amy K, Wilson Katherine L
Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
PLoS Biol. 2004 Sep;2(9):E231. doi: 10.1371/journal.pbio.0020231. Epub 2004 Aug 24.
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.
X连锁型埃默里-德赖富斯肌营养不良症是由emerin（一种核内膜的LEM结构域蛋白）缺失引起的。为了更好地理解emerin的功能，我们使用亲和层析法从HeLa细胞核提取物中纯化emerin结合蛋白。包含肌动蛋白、αII-血影蛋白和其他蛋白质的复合物特异性结合emerin。在有或没有凝溶胶蛋白或封端蛋白存在的情况下进行的肌动蛋白聚合试验表明，emerin结合并稳定肌动蛋白丝的尖端，使肌动蛋白聚合速率提高4至12倍。我们认为emerin有助于在核内膜形成基于肌动蛋白的皮质网络，从概念上讲类似于质膜上的肌动蛋白皮质网络。因此，除了破坏与emerin结合的转录因子外，emerin的缺失可能通过削弱核肌动蛋白网络而使核膜结构不稳定。
