有丝分裂磷酸化将肝癌衍生生长因子激活为一种促有丝分裂原。
Mitotic phosphorylation activates hepatoma-derived growth factor as a mitogen.
作者信息
Everett Allen D, Yang Jun, Rahman Monzur, Dulloor Pratima, Brautigan David L
机构信息
Department of Pediatrics, Cardiology Division, Johns Hopkins University, 600 N. Wolfe Street, Baltimore, MD 21287, USA.
出版信息
BMC Cell Biol. 2011 Apr 13;12:15. doi: 10.1186/1471-2121-12-15.
BACKGROUND
Hepatoma-derived growth factor (HDGF) is a nuclear protein that is a mitogen for a wide variety of cells. Mass spectrometry based methods have identified HDGF as a phosphoprotein without validation or a functional consequence of this post-translational modification.
RESULTS
We found that HDGF in primary mouse aortic vascular smooth muscle cells (VSMC) was phosphorylated. Wild type HDGF was phosphorylated in asynchronous cells and substitution of S103, S165 and S202 to alanine each demonstrated a decrease in HDGF phosphorylation. A phospho-S103 HDGF specific antibody was developed and demonstrated mitosis-specific phosphorylation. HDGF-S103A was not mitogenic and FACS analysis demonstrated a G2/M arrest in HDGF-S103A expressing cells, whereas cells expressing HDGF-S103D showed cell cycle progression. Nocodazole arrest increased S103 phosphorylation from 1.6% to 29% (P = 0.037).
CONCLUSIONS
Thus, HDGF is a phosphoprotein and phosphorylation of S103 is mitosis related and required for its function as a mitogen. We speculate that cell cycle regulated phosphorylation of HDGF may play an important role in vascular cell proliferation.
背景
肝癌衍生生长因子（HDGF）是一种核蛋白，对多种细胞具有促有丝分裂作用。基于质谱的方法已将HDGF鉴定为一种磷酸化蛋白，但未对这种翻译后修饰进行验证或研究其功能后果。
结果
我们发现原代小鼠主动脉血管平滑肌细胞（VSMC）中的HDGF发生了磷酸化。野生型HDGF在异步细胞中被磷酸化，将S103、S165和S202替换为丙氨酸均显示HDGF磷酸化水平降低。我们制备了一种磷酸化S103 HDGF特异性抗体，并证明了其有丝分裂特异性磷酸化。HDGF-S103A没有促有丝分裂作用，流式细胞术分析表明，表达HDGF-S103A的细胞出现G2/M期阻滞，而表达HDGF-S103D的细胞则显示细胞周期进展。诺考达唑阻滞使S103磷酸化水平从1.6%提高到29%（P = 0.037）。
结论
因此，HDGF是一种磷酸化蛋白，S103的磷酸化与有丝分裂相关，是其作为促有丝分裂剂发挥功能所必需的。我们推测，HDGF的细胞周期调控磷酸化可能在血管细胞增殖中起重要作用。
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