Rodriguez-Polo Ignacio, Nielsen Maike, Debowski Katharina, Behr Rüdiger
Platform Degenerative Diseases, German Primate Center (DPZ), Leibniz Institute for Primate Research, Kellnerweg 4, 37077 Göttingen, Germany.
DZHK, German Center for Cardiovascular Research, Partner Site Göttingen, Göttingen, Germany.
Primate Biol. 2017 Nov 20;4(2):231-240. doi: 10.5194/pb-4-231-2017. eCollection 2017.
The protein c-CBL is a ubiquitin ligase. It catalyzes the last step of the transfer of ubiquitin to target proteins. Upon completion of polyubiquitination, the target proteins are degraded. Clinically, it is important that c-CBL is mutated in a subset of patients who develop myeloid malignancies, which are diseases of the hematopoietic stem or progenitor cells. c-CBL has also been shown to be expressed by human spermatogonia. The whole spermatogonial cell population possesses a subset that comprises also the spermatogonial stem cells. Based on these findings we hypothesized that c-CBL might be a general stem cell marker. To test this, we first validated the antibody using marmoset bone marrow and adult testis. In both tissues, the expected staining pattern was observed. Western blot analysis revealed only one band of the expected size. Then, we examined the expression of c-CBL in marmoset monkey embryonic stem (ES) cells, induced pluripotent stem (iPS) cells and adult stem cells. We found that c-CBL is strongly expressed in undifferentiated marmoset iPS cells and ES cells. However, adult stem cells in the gut and the stomach did not express c-CBL, indicating that c-CBL is not a general stem cell marker. In summary, c-CBL is strongly expressed in pluripotent stem cells of the marmoset monkey as well as in selected adult stem cell types. Future studies will define the function of c-CBL in pluripotent stem cells.
蛋白质c-CBL是一种泛素连接酶。它催化泛素转移至靶蛋白的最后一步。多聚泛素化完成后，靶蛋白被降解。临床上，重要的是，在一部分发生髓系恶性肿瘤（造血干细胞或祖细胞疾病）的患者中，c-CBL发生了突变。c-CBL也已被证明由人类精原细胞表达。整个精原细胞群体包含一个子集，其中也包括精原干细胞。基于这些发现，我们推测c-CBL可能是一种通用的干细胞标志物。为了验证这一点，我们首先使用狨猴骨髓和成年睾丸对该抗体进行了验证。在这两种组织中，均观察到了预期的染色模式。蛋白质印迹分析仅显示出一条预期大小的条带。然后，我们检测了c-CBL在狨猴胚胎干细胞、诱导多能干细胞和成体干细胞中的表达。我们发现c-CBL在未分化的狨猴诱导多能干细胞和胚胎干细胞中强烈表达。然而，肠道和胃中的成体干细胞不表达c-CBL，这表明c-CBL不是一种通用的干细胞标志物。总之，c-CBL在狨猴的多能干细胞以及某些成体干细胞类型中强烈表达。未来的研究将确定c-CBL在多能干细胞中的功能。
