Functional in vivo and in vitro analysis of MORC3, which regulates nuclear domain

急性早幼粒细胞白血病（APL）是由造血细胞中PML/RARA融合基因的表达引起的。PML编码一种参与核亚结构域PML-核小体（NBs）形成的蛋白质，并将许多蛋白质（如肿瘤抑制因子p53）招募到PML-NBs中以调节转录。PML/RARA融合蛋白的表达破坏APL中PML- nbs的表达。然而，Pml敲除小鼠不会出现造血功能异常或白血病。我们已经证明，MORC3以依赖于ghl - atp酶氨基末端的方式定位在pml - nb中，并调节p53的定位和转录活性(Mol。医学杂志。单元18,1701-1709,2007)。为了分析MORC3在体内的功能，我们生成了MORC3 -/-小鼠。所有的小鼠在出生时或一天内死亡。在性交后18.5天（dpc）出现了更多的c3 +/+、+/-和-/-胚胎，几乎达到预期的孟德尔比例。Morc3 -/-小鼠在胚胎18.5 dpc时，血管和小胸腺周围有Gr-1和Mac-1双阳性骨髓细胞浸润，肝脏肿大。为了描述Morc3-/-的造血功能异常，我们将14.5 dpc的Morc3-/-或+/+胎肝细胞移植到辐照致死的同基因小鼠体内。移植约2个月后，Morc3 -/-胎肝移植小鼠出现皮肤炎症，皮肤、脾脏和肝脏中有更多的Gr-1和Mac-1双阳性骨髓细胞。这些骨髓细胞向成熟巨噬细胞的分化受到阻碍。MORC3缺乏诱导以c-Kit表达为特征的未成熟髓细胞。我们在1966年的日本癌症协会年会上提出了这些结果，并正在准备论文。

Acute promyelocytic leukemia(APL) is caused by the expression of the PML/RARA fusion gene in hematopoietic cells. PML encodes a protein that is involved in the formation of the nuclear subdomains, PML-nuclear bodies(NBs) and recruits many proteins such as tumor suppressor p53 into PML-NBs to regulate the transcription. The expression of PML/RARA fusion protein disrupts PML-NBs in APL. However, Pml knockout mice do not develop abnormal hematopoiesis or leukemia. We have shown that MORC3 localizes in PML-NBs in a manner dependent on GHL-ATPase at its amino-terminus and regulates the localization and transcriptional activity of p53(Mol. Biol. Cell 18, 1701-1709, 2007) . To analyze functions of MORC3 in vivo, we have generates Morc3 -/- 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. Morc3 -/- mice presented with hepatomegaly by the infiltration of Gr-1 and Mac-1 double positive myeloid cells around vessels and small thymus at 18.5 dpc embryo. To characterize the abnormal hematopoiesis in Morc3-/-, we transplanted 14.5 dpc Morc3 -/- or +/+ fetal liver cells into lethally irradiated syngeneic mice. About two months after transplantation, the Morc3 -/- fetal liver transplanted mice presented with dermal inflammation and had more Gr-1 and Mac-1 double positive myeloid cells in skin, spleen and liver than the wild type transplanted mice. The differentiation of these myeloid cells into mature macrophage was impaired. The deficiency of MORC3 induced immature myeloid cells characterized by c-Kit expression. We presented these results in 66the annual meeting of the Japanese cancer association and are preparing the paper.