PSMA8‐Containing 20S Proteasome Regulates Spermiogenesis and Male Fertility

males could produce round spermatids, but sperm formation is delayed and abnormal, exhibiting a phenotype of oligoasthenoteratozoospermia. s20S is required for the ubiquitination-dependent proteasomal degradation of a group of proteins in elongating spermatids. These s20S-mediated degradation events are essential for liquid-liquid phase separation of FXR1 and thereby translational-activation of its substrates. Taken together, these findings provide an in vivo evidence of protein homeostasis control in spermiogenesis in mammals.