ABSTRACT
Spermatogenesis is a critical and tightly regulated process that ultimately generates mature haploid sperm from diploid spermatogonia. The mammalian target of rapamycin (mTOR) signaling regulates cell growth, metabolism, proliferation and survival by several extracellular and intracellular signals and is considered as one of the key pathways in the regulation of spermatogenesis. This kinase assembles into two, evolutionarily conserved multiprotein complexes, the mTORC1 and mTORC2, which can be differentiated from each other by their unique binding partners and substrates. During spermatogenesis, a fine balance between the spermatogonial stem cell renewal and differentiation is crucial for ensuring continual sperm production, and mTOR signaling regulates this. Further, the polarity of Sertoli cells that helps in providing the essential structural framework and microenvironment for the development of germ cells also requires precise mTOR signaling. The junctional restructuring of the blood-testes barrier (BTB) is synchronized with the timing of the translocation of germ cells into the adluminal compartment by mTOR signaling in the seminiferous tubules. The current chapter presents a brief account of the role of mTOR activity in regulating the crucial balance between spermatogonial stem cells’ (SSCs) self-renewal and differentiation as well as the functionality of the BTB and the Sertoli cell polarity to ensure incessant spermatogenesis. Further, the antagonistic effects of two mTOR complexes in maintaining a functional BTB are also summarized.
