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.

Cutaneous application of alpha-methylspermidine activates the growth of resting hair follicles in mice.

Recent studies using transgenic animals have revealed a crucial role for polyamines in the development and the growth of skin and hair follicles. In mammals, the growth of hair is characterized by three main cyclic phases of transformation, including a rapid growth phase (anagen), an apoptosis-driven regression phase (catagen) and a relatively quiescent resting phase (telogen). The polyamine pool during the anagen phase is higher than in telogen and catagen phases. In this study, we used alpha-methylspermidine, a metabolically stable polyamine analog, to artificially elevate the polyamine pool during telogen. This manipulation was sufficient to induce hair growth in telogen phase mice after 2 weeks of daily topical application. The application site was characterized by typical features of anagen, such as pigmentation, growing hair follicles, proliferation of follicular keratinocytes and upregulation of beta-catenin. The analog penetrated the protective epidermal layer of the skin and could be detected in dermis. The natural polyamines were partially replaced by the analog in the application site. However, the combined pool of natural spermidine and alpha-methylspermidine exceeded the physiological spermidine pool in telogen phase skin. These results highlight the role of polyamines in hair cycle regulation and show that it is possible to control the process of hair growth using physiologically stable polyamine analogs.