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Abstract

Transforming growth factor β3 perturbs the inter-Sertoli tight junction permeability barrier in vitro possibly mediated via its effects on occludin, zonula occludens-1, and claudin-11 (PDF) (HTML) 
Lui,Wing-Yee; Lee,William M.; Cheng,Chuen-yan
Endocrinology 142(5): 1865-1877
Publication date: 2001

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Throughout spermatogenesis, inter-Sertoli tight junctions (TJs)that create the blood-testis barrier in the rat must be disassembledand reassembled to permit the timely passage of preleptotenespermatocytes from the basal to the adluminal compartment ofthe seminiferous epithelium. However, the mechanism(s) and theparticipating molecules that regulate this event are largelyunknown. Although there is no in vitro model to study the eventand regulation of inter-Sertoli TJ disassembly, primary culturesof Sertoli cells in vitro can be used to study junction assembly.In this study, we sought to investigate whether cytokines areinvolved in the inter-Sertoli TJ assembly in vitro. Sertolicells isolated from 20-day-old rats were cultured at a densityof 0.5-1.2 x 10 cells/cm on Matrigel-coated dishes orbicameral units for 8-9 days. The steady-state messengerRNA levels of basic fibroblast growth factor (bFGF), transforminggrowth factor (TGF)-ß2, and TGF-ß3 at differenttime points were assessed by semiquantitative RT-PCR. In selectedexperiments, the assembly of inter-Sertoli TJs was monitored bytransepithelial electrical resistance measurement. It was foundthat there was no change in the expression of basic fibroblastgrowth factor throughout the entire culture period. However,there was a 2-fold reduction in the expression of TGF-ß2and TGF-ß3 at the time inter-Sertoli TJs were beingassembled. On days 5-8, after the inter-Sertoli TJs hadbeen assembled, the Sertoli cell steady-state messenger RNAlevels of TGF-ß2 and TGF-ß3 increased byas much as 3- and 6-fold, respectively, when compared with Sertolicells on days 1-3 when TJs were being assembled. Also,it was found that recombinant TGF-ß3 added to Sertolicells cultured in vitro at 1.2 x 10 cells/cm on Matrigel-coatedbicameral units perturbed the inter-Sertoli TJ permeabilitybarrier dose-dependently. Moreover, the presence of TGF-ß3also inhibited the transient and/or basal expression of severalTJ-associated proteins, which include occludin, zonula occludens-1,and claudin-11 when inter-Sertoli TJs were being assembled invitro. These results suggest that TGF-ß plays a crucialrole in regulating the complicated biochemical events of junctionassembly in the testis.

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