Journal
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Volume 102, Issue 33, Pages 11722-11727Publisher
NATL ACAD SCIENCES
DOI: 10.1073/pnas.0503855102
Keywords
spermatogenesis; ectoplasmic specialization; Sertoli-germ cell interaction
Categories
Funding
- NICHD NIH HHS [U54 HD029990, U01 HD045908, 5U54 HD029990, 5U01 HD045908] Funding Source: Medline
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In the mammalian testis, the blood-testis barrier (BTB), unlike the blood-brain and blood-retina barriers, is composed of coexisting tight junctions (TJs) and adherens junctions (AJs). Yet these junctions must open (or disassemble) to accommodate the migration of preleptotene and leptotene spermatocytes across the BTB during spermatogenesis while maintaining its integrity. In this report, we show that the BTB utilizes a unique engagement and disengagement mechanism to permit the disruption of AJ that facilitates germ cell movement without compromising the BTB integrity. For instance, both TJ (e.g., occludin and JAM-1) and AJ (e.g., N-cadherin) integral membrane proteins were colocalized to the same site at the BTB. Although these TJ- and AJ-integral membrane proteins did not physically interact with each other, they were structurally linked by means of peripheral adaptors (e.g., ZO-1 and alpha- and gamma-catenins). As such, these proteins are structurally engaged under physiological conditions to reinforce the BTB. When rats were exposed to Adjudin to induce AJ restructuring that eventually led to germ cell loss from the epithelium, this structural interaction between occludin and N-cadherin by means of their adaptors became disengaged while their protein levels were significantly induced. In short, when the epithelium is under assault, such as by Adjudin or plausibly at the time of germ cell migration across the BTB during spermatogenesis, the TJ- and A.J-integral membrane proteins can be disengaged. Thus, this mechanism is used by the testis to facilitate AJ restructuring to accommodate germ cell migration while maintaining the BTB integrity.
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