Figure 2.

Autophagy-dependent resource allocation in the male reproductive system. Autophagy participates in somatic-germ cell interactions and spermiogenesis in the male reproductive systems. (a) Autophagy participates in testosterone synthesis by regulating cholesterol uptake. In the Leydig cells, SCARB1 functions as a receptor for high-density lipoprotein, and autophagy promotes cholesterol uptake by eliminating its negative regulator SLC9A3R2. (b) Autophagy is involved in acrosome biogenesis. Autophagy participates in proacrosomic vesicle transport and further fusion into a single acrosome on the nuclear membrane. (c and d) Autophagy regulates cytoplasm removal and sperm head shaping by selective degradation of a negative cytoskeleton assembly regulator (PDLIM1) in both Sertoli cells (c) and spermatids (d). PDLIM1 is degraded by autophagy to ensure the proper organization of the cytoskeleton in the apical ES of the Sertoli cell and in the manchette of spermatids.