Fridkin Alexandra, Mills Erez, Margalit Ayelet, Neufeld Esther, Lee Kenneth K, Feinstein Naomi, Cohen Merav, Wilson Katherine L, Gruenbaum Yosef
Department of Genetics, Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem 91904, Israel.
Proc Natl Acad Sci U S A. 2004 May 4;101(18):6987-92. doi: 10.1073/pnas.0307880101. Epub 2004 Apr 20.
Caenorhabditis elegans mtf-1 encodes matefin, which has a predicted SUN domain, a coiled-coil region, an anti-erbB-2 IgG domain, and two hydrophobic regions. We show that matefin is a nuclear membrane protein that colocalizes in vivo with Ce-lamin, the single nuclear lamin protein in C. elegans, and binds Ce-lamin in vitro but does not require Ce-lamin for its localization. Matefin is detected in all embryonic cells until midembryogenesis and thereafter only in germ-line cells. Embryonic matefin is maternally deposited, and matefin is the first nuclear membrane protein known to have germ line-restricted expression. Animals homozygous for an mtf-1 deletion allele show that matefin is essential for germ line maturation and survival. However, matefin is also required for embryogenesis because mtf-1 (RNAi) embryos die around the approximately 300-cell stage with defects in nuclear structure, DNA content, and chromatin morphology. Down-regulating matefin in mes-3 animals only slightly enhances embryonic lethality, and elimination of UNC-84, the only other SUN-domain gene in C. elegans, has no affect on mtf-1 (RNAi) animals. Thus, mtf-1 mediates a previously uncharacterized pathway(s) required for embryogenesis as well as germ line proliferation or survival.
秀丽隐杆线虫的mtf-1编码伴侣蛋白,其具有一个预测的SUN结构域、一个卷曲螺旋区域、一个抗erbB-2 IgG结构域和两个疏水区域。我们发现伴侣蛋白是一种核膜蛋白,在体内与秀丽隐杆线虫中的单个核纤层蛋白Ce-核纤层蛋白共定位,并且在体外与Ce-核纤层蛋白结合,但在定位过程中不需要Ce-核纤层蛋白。伴侣蛋白在所有胚胎细胞中都能检测到,直到胚胎发育中期,此后仅在生殖系细胞中存在。胚胎伴侣蛋白是母系遗传的,并且伴侣蛋白是已知的第一个具有生殖系限制性表达的核膜蛋白。mtf-1缺失等位基因的纯合动物表明,伴侣蛋白对于生殖系成熟和存活至关重要。然而,伴侣蛋白对于胚胎发育也是必需的,因为mtf-1(RNA干扰)胚胎在大约300细胞阶段左右死亡,伴有核结构、DNA含量和染色质形态的缺陷。在mes-3动物中下调伴侣蛋白只会略微增强胚胎致死率,而消除秀丽隐杆线虫中唯一的另一个SUN结构域基因UNC-84对mtf-1(RNA干扰)动物没有影响。因此,mtf-1介导了一条以前未被描述的胚胎发育以及生殖系增殖或存活所需的途径。