Maintenance of strict developmental stage- and cell type-specific gene expression is critical for the progression of spermatogenesis. However, the mechanisms which sustain the spatiotemporal order of gene transcription within the seminiferous epithelium are poorly understood. Previous work has established that the proximal promoter of the mouse SP-10 gene was sufficient to maintain round spermatid-specific expression (Reddi, P.P., Shore, A.N., Shapiro, J.A., Anderson, A., Stoler, M.H., Acharya, K.K., 2003b. Spermatid-specific promoter of the SP-10 gene functions as an insulator in somatic cells. Dev. Biol. 262, 173-182). The present study addressed the cis-requirement for this regulation and sought to identify the cognate transcription factor(s). We found that mutation of two 5'-ACACAC motifs (at -172 and -160) within the -186/+28 SP-10 promoter led to premature and indiscriminate expression of a reporter gene in the seminiferous epithelium of transgenic mice, whereas the wild-type -186/+28 promoter retained spermatid specificity. Neither promoter showed ectopic expression in the somatic tissues. Expression cloning using the -186/-148 portion of the promoter yielded transcriptional repressors TDP-43 and Puralpha of which TDP-43 required the complementary 5'-GTGTGT elements located on the opposite strand for binding in vitro. Further, Northern analysis and immunohistochemistry of mouse testis showed the presence of TDP-43 in cell-types where the SP-10 gene remains repressed. Taken together, our results demonstrate that 5'-GTGTGT motifs on the complementary strand are required to prevent premature expression of SP-10 during spermatogenesis and implicate TDP-43 as the putative regulatory factor. The study also implied that additional level(s) of regulation keep the SP-10 gene silent in the somatic tissues.

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Oestrogen controls Foxp3 expression in regulatory T cells (Treg cells) via a mechanism thought to involve oestrogen receptor alpha (ERα), but the molecular basis and functional impact of ERα signalling in Treg cells remain unclear. We report that ERα ligand oestradiol (E2) is significantly increased in human cervical cancer (CxCa) tissues and tumour-infiltrating Treg cells (CD4+CD25hiCD127low), whereas blocking ERα with the antagonist ICI 182,780 abolishes FOXP3 expression and impairs the function of CxCa infiltrating Treg cells. Using a novel approach of co-immunoprecipitation with antibodies to E2 for capture, we identified binding of E2:ERα complexes to FOXP3 protein in CxCa-derived Treg cells. Chromatin immunoprecipitation analyses of male blood Treg cells revealed ERα occupancy at the FOXP3 promoter and conserved non-coding DNA elements 2 and 3. Accordingly, computational analyses of the enriched regions uncovered eight putative oestrogen response elements predicted to form a loop that can activate the FOXP3 promoter. Together, these data suggest that E2-mediated ERα signalling is critical for the sustenance of FOXP3 expression and Treg cell function in human CxCa via direct interaction of ERα with FOXP3 promoter. Overall, our work gives a molecular insight into ERα signalling and highlights a fundamental role of E2 in controlling human Treg cell physiology.

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