cAMP perturbs inter-Sertoli tight junction permeability barrier in vitro via its effect on proteasome-sensitive ubiquitination of occludin.

Throughout spermatogenesis, inter-Sertoli tight junctions (TJs) that constitute the blood-testis barrier must be disassembled and reassembled to permit the timely movement of preleptotene and leptotene spermatocytes from the basal to the adluminal compartment of the seminiferous epithelium. However, the mechanism and the participating molecules that regulate the bioavailability of TJ proteins are entirely unknown. Using Sertoli cell culture, it was shown that there was an increase in occludin level, concomitant with a reduction of an E3 ubiquitin ligase, Itch, at the time when inter-Sertoli TJs were assembled. By co-immunoprecipitation, occludin was shown to associate with Itch at the TJs. A novel interaction between Itch and UBC4 (an ubiquitin-conjugating enzyme) was identified. When TJs were disrupted by dibutyryl-cAMP (db-cAMP), an increase in protein levels of Itch and UBC4 along with a significant reduction in endogenous occludin was detected. These results seemingly suggest that the interaction of Itch and UBC4 on occludin is potentially involved in regulating Sertoli TJ dynamics. Addition of a proteasome inhibitor, MG-132, into Sertoli cells cultured with db-cAMP blocked the db-cAMP-induced occludin loss in vitro. Accumulations of ubiquitin-conjugated and Itch-conjugated occludin were detected in Sertoli cells cultured in the presence of both MG-132 and db-cAMP. These results suggest that MG-132 prevented db-cAMP-induced TJ disruption by altering the rate of occludin degradation. Taken collectively, the results reported herein support the notion that db-cAMP-induced TJ disruption was mediated by an induction of Itch protein expression, which in turn triggered the ubiquitination of occludin resulting in TJ disruption.

Lui WY ，Lee WM 《JOURNAL OF CELLULAR PHYSIOLOGY》

Transforming growth factor-beta3 perturbs the inter-Sertoli tight junction permeability barrier in vitro possibly mediated via its effects on occludin, zonula occludens-1, and claudin-11.

Lui WY ，Lee WM ，Cheng CY 《ENDOCRINOLOGY》

Regulation of Sertoli cell tight junction dynamics in the rat testis via the nitric oxide synthase/soluble guanylate cyclase/3',5'-cyclic guanosine monophosphate/protein kinase G signaling pathway: an in vitro study.

Lee NP ，Cheng CY 《ENDOCRINOLOGY》

Is cadmium chloride-induced inter-sertoli tight junction permeability barrier disruption a suitable in vitro model to study the events of junction disassembly during spermatogenesis in the rat testis?

Chung NP ，Cheng CY 《ENDOCRINOLOGY》

The interplay of collagen IV, tumor necrosis factor-alpha, gelatinase B (matrix metalloprotease-9), and tissue inhibitor of metalloproteases-1 in the basal lamina regulates Sertoli cell-tight junction dynamics in the rat testis.

Siu MK ，Lee WM ，Cheng CY 《-》