Induction of collagen expression during inter-sertoli Tight Junction (TJ) assembly in vitro

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The dynamics of Sertoli (SC)-germ cell (GC) anchoring junctions (AJs) are regulated by E-cadherin, N-cadherin and Src

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Thyroid Hormone Function in the Rat Testis

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The dynamics of inter-Sertoli (SC) tight junctions (TJ) are regulated by transforming growth factor-beta 3 (TGF-beta 3) via the p38 mitogen-activated protein (MAP) kinase signaling pathway

published_or_final_versio

Extracellular matrix (ECM) regulates the dynamics of tight junctions (TJs) in the testis possibly via its interactions with cytokines and proteases

Abstract no. 646published_or_final_versio

Disruption of the blood-testis barrier integrity by bisphenol A in vitro: Is this a suitable model for studying blood-testis barrier dynamics?

Bisphenol A, an estrogenic environmental toxicant, has been implicated to have hazardous effects on reproductive health in humans and rodents. However, there are conflicting reports in the literature regarding its effects on male reproductive function. In this study, it was shown that in adult rats treated with acute doses of bisphenol A, a small but statistically insignificant percentage of seminiferous tubules in the testes displayed signs of germ cell loss, consistent with some earlier reports. It also failed to disrupt the blood-testis barrier in vivo. This is possibly due to the low bioavailability of free bisphenol A in the systemic circulation. However, bisphenol A disrupted the blood-testis barrier when administered to immature 20-day-old rats, consistent with earlier reports concerning the higher susceptibility of immature rats towards bisphenol A. This observation was confirmed using primary Sertoli cells cultured in vitro with established tight junction-permeability barrier that mimicked the blood-testis barrier in vivo. The reversible disruption of Sertoli cell tight junction barrier by bisphenol A was associated with an activation of ERK, and a decline in the levels of selected proteins at the tight junction, basal ectoplasmic specialization, and gap junction at the blood-testis barrier. Studies by dual-labeled immunofluorescence analysis and biotinylation techniques also illustrated declining levels of occludin, connexin 43, and N-cadherin at the cell-cell interface following bisphenol A treatment. In summary, bisphenol A reversibly perturbs the integrity of the blood-testis barrier in Sertoli cells in vitro, which can also serve as a suitable model for studying the dynamics of the blood-testis barrier. © 2009 Elsevier Ltd. All rights reserved.postprin

Ectoplasmic specialization: A friend or a foe of spermatogenesis?

The ectoplasmic specialization (ES) is a testis-specific, actin-based hybrid anchoring and tight junction. It is confined to the interface between Sertoli cells at the blood-testis barrier, known as the basal ES, as well as between Sertoli cells and developing spermatids designated the apical ES. The ES shares features of adherens junctions, tight junctions and focal contacts. By adopting the best features of each junction type, this hybrid nature of ES facilitates the extensive junction-restructuring events in the seminiferous epithelium during spermatogenesis. For instance, the α6β1-integrin- laminin 333 complex, which is usually limited to the cell-matrix interface in other epithelia to facilitate cell movement, is a putative apical ES constituent. Furthermore, JAM-C and CAR, two tight junction integral membrane proteins, are also components of apical ES involving in spermatid orientation. We discuss herein the mechanisms that maintain the cross-talk between ES and blood-testis barrier to facilitate cell movement and orientation in the seminiferous epithelium. © 2006 Wiley Periodicals, Inc.postprin

Differential interactions between transforming growth factor-β3/ TβR1, TAB1, and CD2AP disrupt blood-testis barrier and sertoli-germ cell adhesion

The biochemical basis that regulates the timely and selective opening of the blood-testis barrier (BTB) to migrating preleptotene/leptotene spermatocytes at stage VIII of the epithelial cycle in adult rat testes is virtually unknown. Recent studies have shown that cytokines (e.g. transforming growth factor (TGF)-β3) may play a crucial role in this event. However, much of this information relies on the use of toxicants (e.g. CdCl 2), making it difficult to relay these findings to normal testicular physiology. Here we report that overexpression of TGF-β3 in primary Sertoli cells cultured in vitro indeed perturbed the tight junction (TJ) barrier with a concomitant decline in the production of BTB constituent proteins as follows: occludin, N-cadherin, and ZO-1. Additionally, local administration of TGF-β3 to testes in vivo was shown to reversibly perturb the BTB integrity and Sertoli-germ cell adhesion via the p38 MAPK and ERK signaling pathways. Most importantly, the simultaneous activation of p38 and ERK signaling pathways is dependent on the association of the TGF-β3-TβR1 complex with adaptors TAB1 and CD2AP because if TβR1 was associated preferentially with CD2AP, only Sertoli-germ cell adhesion was perturbed without compromising the BTB. Collectively, these data illustrate that local production of TGF-β3, and perhaps other TGF-βs and cytokines, by Sertoli and germ cells into the microenvironment at the BTB during spermatogenesis transiently perturbs the BTB and Sertoli-germ cell adhesion to facilitate germ cell migration when the activated TβRI interacts with adaptors TAB1 and CD2AP. However, TGF-β3 selectively disrupts Sertoli-germ cell adhesion in the seminiferous epithelium to facilitate germ cell migration without compromising BTB when TβRI interacts only with adaptor CD2AP. © 2006 by The American Society for Biochemistry and Molecular Biology, Inc.postprin

Fasting plasma zeaxanthin response to Fructus barbarum L. (wolfberry; Kei Tze) in a food-based human supplementation trial

Antioxidant Research Group, Faculty of Health & Social Sciences2004-2005 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe