Regulation of Hippo pathway components by FSH in testis.

The transition of testicular Sertoli cells (Sc) from a proliferative state during infancy to a non proliferative functionally mature state at the onset of puberty is essential for proper spermatogenic progression. The Hippo signaling pathway is a conserved growth control pathway that has been shown to play a crucial role in regulating proliferation and differentiation of different cell types. However, the expression pattern of the pathway components relative to proliferative infant Sc and functionally mature pubertal Sc is not known. In this study, we show that the Hippo pathway components are differentially expressed in infant and pubertal rat Sc. Interestingly, Hippo transducer- YAP was found to be significantly up-regulated in pubertal Sc as compared to infant Sc. Follicle stimulating hormone (FSH) was found to up-regulate Yap expression in pubertal Sc but not in infant Sc. Moreover, FSH induced the phosphorylation of YAP at Ser 127 residue (which is associated with its inactivation) in pubertal Sc. This indicated negative regulation of YAP by FSH mediated signaling in pubertal Sc. Our results demonstrated the differential expression of Hippo pathway genes in infant and pubertal Sc and also established an important role of FSH in regulating YAP expression and phosphorylation in Sc.