A new protein, MORC3,that regulates nuclear localization of proteins, and MORC protein family

在致癌信号、转录调控、端粒维持和细胞衰老中，蛋白质通过募集到核亚区来调节。我们证明MORC3参与了PML小体中蛋白质的条件性或结构性定位。在表达MORC3的细胞中，Sp100定位于PML-NBS中，而在表达ATPase缺陷的MORC3突变体(E35A)中，Sp100分散在整个细胞核中，而在表达MORC3的细胞中，则通过shRNA表达。抑癌基因P53通过致癌信号被募集到PML-NBS中。MORC3过表达介导PML-NBS的P53募集。在对P53反应元件或p21或Bax的启动子的荧光素酶报告基因分析中，MORC3而不是MORC3-E35A增强了P53的转录激活。此外，MORC3还可诱导内源性p21的表达。此外，我们还培育了靶向Morc3的小鼠。所有Morc3-/-小鼠在出生时或一天内死亡。性交后18.5天的Morc3/、/-和-/-胚胎的比例几乎达到了预期的孟德尔比例。我们从14.5DPC的Morc3/和-/-胚胎中获得了小鼠胚胎成纤维细胞(MEF)。在Morc3-/-MEF中，p53通过翻译后修饰(包括丝氨酸18和23位的磷酸化)稳定下来，但几乎不能被阿霉素激活。Morc3-/-小鼠表现出髓系和小胸腺的异常发育。MORC家族蛋白(人的MORC1、MORC2、MORC3和MORC4以及小鼠的Morc1、Morc2a、Morc2b、Morc3和Morc4)的新命名被我们提出，并被Hugo和MGD接受。

In oncogenic signals, transcriptional regulation, telomere maintenance and cellular senescence, proteins are regulated by recruitment into nuclear subdomains. We show that MORC3 is involved in the conditional or constitutive localization of proteins in PML-body. Sp100 is localized in PML-NBs in MORC3-expressing cells but dispersed into entire nuclei in ATPase-deficient MORC3 mutant (E35A) expressing cells and in MORC3-repressed cells by shRNA expression. The tumor suppressor p53 is recruited into PML-NBs by oncogenic signal. Overexpression of MORC3 mediated p53 recruitment into PML-NBs. MORC3 but not MORC3-E35A enhanced p53-transcriptional activation in luciferase reporter gene analyses for p53-responsive elements, or the promoters of p21 or Bax. In addition, MORC3 induced endogenous p21 expression. Furthermore, we generated Morc3-targeted mice. All Morc3-/- mice died at birth or within a day. Morc3+/+, +/- and -/- embryos at 18.5 days postcoitum (dpc) were present at almost the expected Mendelian ratio. We generated mouse embryonic fibroblasts (MEFs) from Morc3+/+ and -/- embryos at 14.5 dpc. In Morc3-/- MEFs, p53 was stabilized through posttranslational modification including phosphorylation at serine 18 and 23 but barely activated by the treatment of adriamycin.Morc3-/- mice showed abnormal development of myeloid lineage and small thymus. In vitro CFU assay by Morc3-/- fetal liver, GM-CSF but not M-CSF mediated development to monocyte.New nomenclature for MORC family proteins (MORC1,MORC2,MORC3 and MORC4 in human and Morc1,Morc2a, Morc2b, Morc3 and Morc4 in mouse) were proposed by us and accepted in HUGO and MGD.