BMP, Kit and Mitf on melanocytes and melanoma cells

我们先前建立了三个不同的小鼠神经脊(NC)细胞群体，即NCCmelb4、NCCmelb4M5和NCCmer5。BMP4被激活，并参与大多数未成熟黑素细胞前体细胞Kit表达的调节。我们进一步研究了BMP4对体外培养的野生型小鼠NC细胞的影响。与未经处理的对照组相比，在培养液中添加BMP4可增加Kit阳性细胞的数量。我们已经确定BMP4是青春期前Kit阴性的黑素母细胞在进入Kit依赖的黑素合成周期之前的一个重要因素。Western blotting显示Ret蛋白在NCCmelb4M5和Mel-Ret细胞中有表达，而在NCCmelb4和NCCmer5细胞中未见表达。免疫组织化学染色显示NCCmelb4M5和Mel-Ret细胞Ret阳性，而NCCmelb4和NCCmer5细胞Ret阴性。因此，Ret蛋白在大多数未成熟的黑素母细胞中表达，而黑素细胞不表达Ret。基于这些发现，Ret和BMP4的联合作用可能为理解黑素细胞发育中的作用和工作机制提供重要线索。

We previously established three distinct cell populations of mouse neural crest (NC) cells, NCCmelb4, NCCmelb4M5 and NCCmelan5. BMP4 is activated and is involved in the regulation of Kit expression on most immature melanocyte precursors. We further investigated the influence of BMP4 in vitro using primary NC cells cultured from wild-type mice. Addition of BMP4 to the medium increased the number of Kit-positive cells compared to untreated controls. We have identified BMP4 as an important factor for prepubertal Kit-negative melanoblasts just prior to entering the Kit-dependent cycle of melanogenesis. Western blotting revealed expression of the Ret protein in NCCmelb4M5 and in Mel-Ret cells, but in contrast, there was no expression of the Ret protein in NCCmelb4 or NCCmelan5 cells. Immunostaining revealed that NCCmelb4M5 and Mel-Ret cells are positive for Ret, but NCCmelb4 and NCCmelan5 cells are negative for Ret. Thus, Ret protein is expressed in most immature melanoblasts, while melanocytes are negative for Ret. Based on these findings, the combined effects of Ret and BMP4 might provide important clues towards understanding the roles and working mechanisms in melanocyte development.