Work

An intracellular trafficking pathway in the seminiferous epithelium regulating spermatogenesis: a biochemical and molecular perspective

Year: 2009

Type: review

Abstract: During spermatogenesis in adult rat testes, fully developed spermatids (i.e. spermatozoa) at the luminal edge of the seminiferous epithelium undergo "spermiation" at stage VIII of the seminiferous epithelial cycle. This is manifested by the disruption of the apical ectoplasmic specialization (apical ES) so that spermatozoa can enter the tubule lumen and to complete their maturation in the epididymis. At the same time, the blood-testis barrier (BTB) located near the basement membrane undergoes extensive restructuring to allow transit of preleptotene spermatocytes so that post-meiotic germ cells complete their development behind the BTB. While spermiation and BTB restructuring take place concurrently at opposite ends of the Sertoli cell epithelium, the biochemical mechanism(s) by which they are coordinated were not known until recently. Studies have shown that fragments of laminin chains are generated from the laminin/integrin protein complex at the apical ES via the action of MMP-2 (matrix metalloprotease-2) at spermiation. These peptides serve as the local autocrine factors to destabilize the BTB. These laminin peptides also exert their effects on hemidesmosome which, in turn, further potentiates BTB restructuring. Thus, a novel apical ES-BTB-hemidesmosome regulatory loop is operating in the seminiferous epithelium to coordinate these two crucial cellular events of spermatogenesis. This functional loop is further assisted by the Par3/Par6-based polarity protein complex in coordination with cytokines and testosterone at the BTB. Herein, we provide a critical review based on the latest findings in the field regarding the regulation of these cellular events. These recent findings also open up a new window for investigators studying blood-tissue barriers.

Source: Critical Reviews in Biochemistry and Molecular Biology

DOI: 10.1080/10409230903061207

Authors: C. Yan Cheng, Dolores D. Mruk

Institution: Population Council

Language: English

Topic: Sperm and Testicular Function

Subfield: Reproductive Medicine

Field: Medicine

Domain: Health Sciences

Open Access status: green

Funders: National Institutes of Health, Eunice Kennedy Shriver National Institute of Child Health and Human Development

Awards: G1409385275, Junction Dynamics and Male Fertility Regulation, Biology of the Blood-Testis Barrier, An in vivo model to study blood-testis barrier dynamics, Cooperative Contraceptive Research Center: New Contraceptives with Dual Benefits