Schoft Vera K, Beauvais Ariane J, Lang Carmen, Gajewski Andreas, Prüfert Kristina, Winkler Christoph, Akimenko Marie-Andrée, Paulin-Levasseur Micheline, Krohne Georg
Division of Electron Microscopy, Biocenter of the University of Wü rzburg, Am Hubland, Germany.
J Cell Sci. 2003 Jun 15;116(Pt 12):2505-17. doi: 10.1242/jcs.00450. Epub 2003 May 6.
Zebrafish lamina-associated polypeptides 2 (ZLAP2) beta, gamma and omega have in common an N-terminal region with a LEM domain, and in the C-terminal half of the molecule a lamina binding domain and a membrane spanning sequence. The maternally synthesized omega is the largest isoform and the only LAP2 present in the rapidly dividing embryonic cells up to the gastrula stage. ZLAP2omega levels decrease during development, concomitant with the increase of the somatic isoforms ZLAP2beta and gamma. In somatic zebrafish cells ZLAP2gamma is the predominant isoform, whereas only small amounts of ZLAP2beta are present. During early embryonic development, ZLAP2omega becomes associated with mitotic chromosomes before anaphase. The surface of these chromosomes is decorated with vesicles, and each chromosome assembles its own nuclear envelope at the end of mitosis (karyomere formation). Ectopically expressed ZLAP2omega-green fluorescent protein (GFP) fusion protein targets vesicles to mitotic chromosomes in Xenopus A6 cells, suggesting that ZLAP2omega is involved in karyomere formation during early zebrafish development. When ZLAP2beta and gamma were expressed as GFP fusion proteins in Xenopus A6 cells, the beta- but not the gamma-isoform was found in association with mitotic chromosomes, and ZLAP2beta-containing chromosomes were decorated with vesicles. Further analysis of ZLAP2-GFP fusion proteins containing only distinct domains of the ZLAP2 isoforms revealed that the common N-terminal region in conjunction with beta- or omega-specific sequences mediate binding to mitotic chromosomes in vivo.
斑马鱼核纤层相关多肽2（ZLAP2）的β、γ和ω亚型在N端区域都有一个LEM结构域，在分子的C端有一个核纤层结合结构域和一个跨膜序列。母源合成的ω亚型是最大的异构体，也是原肠胚阶段之前快速分裂的胚胎细胞中唯一存在的LAP2。在发育过程中，ZLAP2ω的水平下降，同时体细胞异构体ZLAP2β和γ的水平增加。在斑马鱼体细胞中，ZLAP2γ是主要的异构体，而只有少量的ZLAP2β存在。在胚胎早期发育过程中，ZLAP2ω在后期之前与有丝分裂染色体结合。这些染色体的表面布满了小泡，并且每个染色体在有丝分裂结束时（核小体形成）组装自己的核膜。在非洲爪蟾A6细胞中，异位表达的ZLAP2-绿色荧光蛋白（GFP）融合蛋白将小泡靶向到有丝分裂染色体，这表明ZLAP2ω参与斑马鱼早期发育过程中的核小体形成。当ZLAP2β和γ在非洲爪蟾A6细胞中作为GFP融合蛋白表达时，发现β异构体而不是γ异构体与有丝分裂染色体结合，并且含有ZLAP2β的染色体布满了小泡。对仅包含ZLAP2异构体不同结构域的ZLAP2-GFP融合蛋白的进一步分析表明，共同的N端区域与β或ω特异性序列一起介导了体内与有丝分裂染色体的结合。
