Spermiation

The β1-integrin-p-FAK-p130Cas-DOCK180-RhoA-vinculin is a novel regulatory protein complex at the apical ectoplasmic specialization in adult rat testes

“…Nonetheless, subsequent studies from another laboratory have confirmed this earlier observation that p-FAK is indeed tightly associated with the apical ES in rat testes 18 and it is critical to be involved in the process of sperm release during spermiation. 5 Additionally, we have also demonstrated in recent studies that FAK is also an integrated component of the occludin-ZO-1 complex, regulating the Sertoli cell tight junction-permeability barrier at the SertoliSertoli cell interface. 38,39 Herein, we further expand our earlier observations to identify other components of this β1-integrin-FAK cell adhesion complex at the apical ES, illustrating this complex may be used to induce rapid "adhesion" and "de-adhesion" at the β1-integrin-based apical ES during spermiogenesis to facilitate changes in spermatid cell shape and its relative position in the seminiferous epithelium via the action of FAK-induced phosphorylation and the RhoA-mediated cytoskeletal dynamics.…”

“…1,4 Spermiogenesis is typified by the condensation of nuclear materials in the spermatid head, the development of acrosome above the head region, the packaging of the mitochondria in the mid-piece, the elongation of the tail and the shedding of the unwanted cytosolic materials as the residual body to be engulfed by Sertoli cells, so that fully developed spermatids (spermatozoa) can be released from the seminiferous epithelium at spermiation. [5][6][7] However, developing spermatids remain attached to the Sertoli cell in the seminiferous epithelium until spermiation to obtain the needed nourishments, structural and hormonal supports from Sertoli cells. From steps 8 through 19 elongating spermatids, these differentiating cells remain anchored onto the Sertoli cell via a testis-specific atypical adherens junction (AJ) type known as apical ectoplasmic specialization (apical ES).…”

Autophagy is required for ectoplasmic specialization assembly in sertoli cells

“…The apical ES disassembly facilitates the release of spermatozoa during spermiation. 6,17,18 Both basal and apical ES undergo recycling at the late stages of the epithelial cycle so that the ES proteins can be endocytosed, transcytosed and recycled to assemble new apical and basal ES. 9,19 The extensive restructuring of basal and apical ES is crucial to spermatogenesis, and recent studies have shown many molecules and signaling pathways participate in ES restructuring.…”

Actin binding proteins and spermiogenesis

“…39 More importantly, drebrin E was highly expressed at the apical ES at stage VII, 67 co-localizing with Arp3 to the concave side of the elongating spermatid head where extensive endocytic vesicle-mediated protein trafficking events are known to take place, begining at stage VII to prepare for the release of sperm at spermiation at stage VIII. 7,23 Recent studies have shown that proteins known to be involved in protein endocytosis, namely clathrin, cortactin and N-WASP, are also found at the same site. 39,40,69 Additionally, drebrin E was found to structurally interact with Arp3, but not with occludin, FAK, β-catenin and Esp8 in the testis.…”

“…[6][7][8] During spermiogenesis, spermatids undergo a series of morphological changes which are categorized into steps. These are manifested by the condensation of genetic material in the spermatid head, formation of the acrosome over the nucleus, packaging of mitochondria into the mid-piece and elongation of the tail, and they can be classified into 19, 16 and 12 steps in rats, mice and humans, respectively.…”