Sagara Junji, Higuchi Tsukasa, Hattori Yukiko, Moriya Mie, Sarvotham Haritha, Shima Hiroshi, Shirato Haruki, Kikuchi Kunimi, Taniguchi Shunichiro
Department of Molecular Oncology, Institute on Aging and Adaptation, Shinshu University Graduate School of Medicine, 3-1-1 Asahi, Matsumoto 390-8621, Japan.
J Biol Chem. 2003 Nov 14;278(46):45611-9. doi: 10.1074/jbc.M305227200. Epub 2003 Aug 17.
It is thought that the nuclear nonchromatin structures, such as the nuclear matrix and lamina, play regulatory roles in gene expression. In this study, we identified an insoluble protein that was associated with the chromatin-depleted nuclear structure of proliferating human leukemia HL-60 cells. Preparation of the chromatin-depleted nuclear structure, referred to as the nuclear matrix-intermediate filament scaffold (Fey, E., Krochmalnic, G., and Penman, S. (1986) J. Cell. Biol. 102, 1654-1665), involved cell extraction using a series of buffers containing Triton X-100, DNase I, and 2 M NaCl. A yeast two-hybrid assay revealed that this protein bound to the catalytic subunit of protein phosphatase-1 (PP1). Furthermore, it inhibited PP1 activity in vitro. We therefore named it scapinin (scaffold-associated PP1 inhibiting protein). cDNA cloning revealed that scapinin had two splicing variants of 448 amino acids (scapinin-S) and 518 amino acids (scapinin-L). Scapinin was down-regulated by differentiation in HL-60 cells. These results suggest that scapinin is a putative regulatory subunit of PP1 and is involved in transformed or immature phenotypes of HL-60 cells. We also describe the presence of scapinin family proteins from worm to human.
据认为，核非染色质结构，如核基质和核纤层，在基因表达中发挥调节作用。在本研究中，我们鉴定出一种不溶性蛋白质，它与增殖的人白血病HL-60细胞的无染色质核结构相关。制备无染色质核结构，即核基质-中间丝支架（Fey, E., Krochmalnic, G., and Penman, S. (1986) J. Cell. Biol. 102, 1654 - 1665），涉及使用一系列含有 Triton X-100、DNase I 和 2 M NaCl 的缓冲液对细胞进行抽提。酵母双杂交分析表明，该蛋白质与蛋白磷酸酶-1（PP1）的催化亚基结合。此外，它在体外抑制PP1活性。因此，我们将其命名为scapinin（支架相关PP1抑制蛋白）。cDNA克隆显示，scapinin有两种剪接变体，分别为448个氨基酸（scapinin-S）和518个氨基酸（scapinin-L）。在HL-60细胞中，scapinin随分化而下调。这些结果表明，scapinin是PP1的一个假定调节亚基，并且参与HL-60细胞的转化或未成熟表型。我们还描述了从蠕虫到人类均存在scapinin家族蛋白。
