Heat-induced stress response in germ and somatic testicular cells: involvement of SUMO proteins.

Abby M Feldman, Yeshiva University Carol Benichuo, Yeshiva University Nolan Skop, Yeshiva University Margarita Vigodner, Yeshiva University

Abstract Spermatogenesis or sperm production consists of proliferation of spermatogonia, meiosis of spermatocytes and differentiation of spermatids, coordinate processes supported by hormones and growth factors released from testicular somatic Sertoli and Leydig cells. Successful progression through spermatogenesis is crucial for normal gamete formation and the transfer of genetic information to the next generations. It is known that an elevated temperature may affect sperm development; however, the exact mechanisms have not yet been elucidated upon. In this study, we used spermatogonia and Setoli cell-derived cells lines in order to understand the differential effect of heat on germ and somatic testicular cells. Using combined Annexin -5 and Propidium iodide staining as markers for early and late apoptosis correspondingly, we found Sertoli cells to be more susceptible to the effect of elevated temperatures. In addition, we are interested in characterizing the role of novel small proteins known as SUMO (for small-ubiquitin-related modifiers) in response to the stress caused by heat. SUMO proteins were implicated in diverse cellular events, including stress response, in other tissues, but their reproductive function is largely unknown. Our data, obtained after exposure of the testicular cells to increased temperatures, reveals significant changes in SUMO expression level and localization pattern within the spermatogonia and Sertoli cell nuclei. Together our data suggests that Sertoli, not germ cells, are the primary target of the heat stress in the testis and revealed a specific role for SUMO proteins playing in the heat mediated stress response. Studies are in progress to confirm these results using cells freshly isolated from mouse testis.

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