Expression analysis of Tudor-SN protein in mouse tissues

Tudor-SN (SND1, p100) has been shown to function as a transcriptional coactivator as well as a modulator of RNA metabolism and biogenesis and a component in the RNA-induced silencing complex (RISC). Tudor-SN consists of five repeats of staphylococcus nuclease-like domains (SN1-SN5) and, a Tudor domain implicated in binding to methylated ligands. The protein is highly conserved through evolution from fission yeast to mammals and it exists as a single gene without any close homologs. Tudor-SN is found to be overexpressed in several cancers such as colon adenocarcinomas and prostate cancer. The conservation of Tudor-SN along evolution suggests it may have important functions; however, the physiological function of Tudor-SN has not yet been characterized. In this study we analyzed the expression and localization of Tudor-SN in mouse tissues and organs by immunohistochemistry, fluorescent immunostaining, Western blotting and RT-qPCR. Expression analysis indicated that Tudor-SN is widely expressed in most organs with the exception of muscle cells. Up-regulated expression was observed in rapidly dividing cells and progenitor cells such as in spermatogonial cells in testis, in the follicular cells of ovary, in the cells of crypts of Lieberkühn of ileum and basal keratinocytes of skin and hair follicle when compared to more differentiated or terminally differentiated cells in the respective organs. Moreover, Tudor-SN was robustly expressed in T-cells and Tudor-SN was co-expressed with CD3 in T-cells in the Peyer's patch, spleen and lymph node. The wide expression pattern of Tudor-SN and high expression in proliferating and self-differentiating cells suggests that the protein serves functions related to activated state of cells.