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Blood-Testis Barrier

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C. Yan Cheng – One of the best experts on this subject based on the ideXlab platform.

  • Transcriptional regulation of cell adhesion at the Blood-Testis Barrier and spermatogenesis in the testis.
    Advances in Experimental Medicine and Biology, 2020
    Co-Authors: C. Yan Cheng

    Abstract:

    Spermatogenesis involves precise co-ordination of multiple cellular events that take place in the seminiferous epithelium composed of Sertoli cells and developing germ cells during the seminiferous epithelial cycle. Given the cyclic and co-ordinated nature of spermatogenesis, temporal and spatial expression of certain genes pertinent to a specific cellular event are essential. As such, transcriptional regulation is one of the major regulatory machineries in controlling the cell type- and stage-specific gene expression, some of which are under the influence of gonadotropins (e.g., FSH and LH) and sex steroids (e.g., testosterone and estradiol-17β). Recent findings regarding transcriptional control of spermatogenesis, most notably target genes at the Sertoli-Sertoli and Sertoli-spermatid interface at the site of the Blood-Testis Barrier (BTB) and apical ectoplasmic specialization (apical ES), respectively, involving in cell adhesion are reviewed and discussed herein. This is a much neglected area of research and a concerted effort by investigators is needed to understand transcriptional regulation of cell adhesion function in the testis particularly at the BTB during spermatogenesis.

  • Blood-Testis Barrier
    Encyclopedia of Reproduction, 2020
    Co-Authors: Linxi Li, C. Yan Cheng

    Abstract:

    In the mammalian testis, the Blood-Testis Barrier (BTB) is an important ultrastructure in the epithelium of the seminiferous tubule—the functional unit of the testis that produces sperm—to support spermatogenesis. For instance, studies using multiple animal models have shown that a disruption of the BTB always leads to an impairment in spermatogenesis, including defects in meiosis, spermiogenesis, and spermatid cell differentiation and survival—cellular events that take place behind the BTB in the adluminal (apical) compartment of the seminiferous epithelium. In this article, besides summarizing the unique morphological features of the BTB, and many of its known functions including its role in supporting spermatogenesis, we focus on recent findings regarding the biology of a local autocrine-based functional axis known as the apical ectoplasmic specialization (apical ES)-Blood-Testis Barrier/basal ES-the basement membrane axis in the testis, which is essential to maintain the homeostasis of the BTB. Specifically, we focus on the role of biologically active peptides generated at the apical ES and also at the basement membrane in the testis during the epithelial cycle of spermatogenesis, and their intriguing antagonistic effects on the BTB function. We also put forth a hypothetic model based on these data to serve as a framework for investigators in the field who seek to better understand the BTB biology.

  • antagonistic effects on Blood-Testis Barrier dynamics in the rat
    , 2020
    Co-Authors: Dolores D. Mruk, Linlin Su, C. Yan Cheng

    Abstract:

    Focaladhesionkinase(FAK),anonreceptorproteintyrosinekinase,displays phosphorylation-dependent localization in the seminifer-ous epithelium of adult rat testes. FAK is an integrated componentof the blood–testis Barrier (BTB) involved in regulating Sertoli celladhesion via its effects on the occludin–zonula occludens-1 com-plex. Herein, we report that p-FAK-Tyr

Dolores D. Mruk – One of the best experts on this subject based on the ideXlab platform.

  • antagonistic effects on Blood-Testis Barrier dynamics in the rat
    , 2020
    Co-Authors: Dolores D. Mruk, Linlin Su, C. Yan Cheng

    Abstract:

    Focaladhesionkinase(FAK),anonreceptorproteintyrosinekinase,displays phosphorylation-dependent localization in the seminifer-ous epithelium of adult rat testes. FAK is an integrated componentof the blood–testis Barrier (BTB) involved in regulating Sertoli celladhesion via its effects on the occludin–zonula occludens-1 com-plex. Herein, we report that p-FAK-Tyr

  • Monitoring the Integrity of the Blood-Testis Barrier (BTB): An In Vivo Assay
    Methods of Molecular Biology, 2018
    Co-Authors: Haiqi Chen, Dolores D. Mruk, Xiang Xiao, Renshan Ge, Qingquan Lian, Lee Wm, Bruno Silvestrini, Cy Cheng

    Abstract:

    The Blood-Testis Barrier is a unique ultrastructure in the mammalian testis, located near the basement membrane of the seminiferous tubule that segregates the seminiferous epithelium into the basal and the adluminal (apical) compartment. Besides restricting paracellular and transcellular passage of biomolecules (e.g., paracrine factors, hormones), water, electrolytes, and other substances including toxicants and/or drugs to enter the adluminal compartment of the epithelium, the BTB is an important ultrastructure that supports spermatogenesis. As such, a sensitive and reliable assay to monitor its integrity in vivo is helpful for studying testis biology. This assay is based on the ability of an intact BTB to exclude the diffusion of a small molecule such as sulfo-NHS-LC-biotin (C20H29N4NaO9S2, Mr. 556.59, a water-soluble and membrane-impermeable biotinylation reagent) from the basal to the apical compartment of the seminiferous epithelium. Herein, we summarize the detailed procedures on performing the assay and to obtain semiquantitative data to assess the extent of BTB damage when compared to positive controls, such as treatment of rats with cadmium chloride (CdCl2) which is known to compromise the BTB integrity.

  • Annexin A2 is critical for Blood-Testis Barrier integrity and spermatid disengagement in the mammalian testis
    Biochimica et Biophysica Acta, 2016
    Co-Authors: Katarzyna Chojnacka, Barbara Bilińska, Dolores D. Mruk

    Abstract:

    Abstract Throughout spermatogenesis, two important processes occur at late stage VIII of the seminiferous epithelial cycle in the rat testis: preleptotene spermatocytes commence entry into the adluminal compartment and step 19 spermatids release from the seminiferous epithelium. Presently, it is not clear how these processes, which involve extensive restructuring of unique Sertoli–Sertoli and Sertoli–germ cell junctions, are mediated. We aimed to determine whether annexin A2 (ANXA2), a Ca 2 + -dependent and phospholipid-binding protein, participates in cell junction dynamics. To address this, in vitro and in vivo RNA interference studies were performed on prepubertal Sertoli cells and adult rat testes. The endpoints of Anxa2 knockdown were determined by immunoblotting, morphological analyses, fluorescent immunostaining, and Barrier integrity assays. In the testis, ANXA2 localized to the Sertoli cell stalk, with specific staining at the blood–testis Barrier and the concave (ventral) surface of elongated spermatids. ANXA2 also bound actin when testis lysates were used for immunoprecipitation. Anxa2 knockdown was found to disrupt the Sertoli cell/blood–testis Barrier in vitro and in vivo. The disruption in Barrier function was substantiated by changes in the localization of claudin-11, zona occludens-1, N-cadherin, and β-catenin. Furthermore, Anxa2 knockdown resulted in spermiation defects caused by a dysfunction of tubulobulbar complexes, testis-specific actin-rich ultrastructures that internalize remnant cell junction components prior to spermiation. Additionally, there were changes in the localization of several tubulobulbar complex component proteins, including actin-related protein 3, cortactin, and dynamin I/II. Our results indicate that ANXA2 is critical for the integrity of the blood–testis Barrier and the timely release of spermatids.

Linlin Su – One of the best experts on this subject based on the ideXlab platform.

  • antagonistic effects on Blood-Testis Barrier dynamics in the rat
    , 2020
    Co-Authors: Dolores D. Mruk, Linlin Su, C. Yan Cheng

    Abstract:

    Focaladhesionkinase(FAK),anonreceptorproteintyrosinekinase,displays phosphorylation-dependent localization in the seminifer-ous epithelium of adult rat testes. FAK is an integrated componentof the blood–testis Barrier (BTB) involved in regulating Sertoli celladhesion via its effects on the occludin–zonula occludens-1 com-plex. Herein, we report that p-FAK-Tyr

  • Regulation of the Blood-Testis Barrier by coxsackievirus and adenovirus receptor
    American Journal of Physiology-cell Physiology, 2012
    Co-Authors: Linlin Su, Dolores D. Mruk, C. Yan Cheng

    Abstract:

    The Blood-Testis Barrier (BTB) divides the seminiferous epithelium into the basal and the adluminal compartment. It restricts paracellular diffusion of molecules between Sertoli cells, confers cell polarity, and creates a unique microenvironment in the adluminal compartment for spermatid development. However, it undergoes restructuring during the epithelial cycle so that preleptotene spermatocytes differentiated from type B spermatogonia residing in the basal compartment can traverse the BTB at stage VIII of the cycle, while the immunological Barrier is maintained. Herein, coxsackievirus and adenovirus receptor (CAR), a tight junction (TJ) integral membrane protein in the testis and multiple epithelia and endothelia, was found to act as a regulatory protein at the BTB, besides serving as a structural adhesion protein. RNAi-mediated knockdown of CAR in a Sertoli cell epithelium with an established TJ-permeability Barrier that mimicked the BTB in vivo resulted in a disruption of the TJ Barrier and an increase in endocytosis of the TJ-protein occludin. Furthermore, such an enhancement in occludin endocytosis was accompanied by a downregulation of Thr-phosphorylation in occludin and an increase in the association of endocytosed occludin with early endosome antigen-1. These findings were confirmed by overexpressing CAR in Sertoli cells, which was found to “tighten” the Sertoli cell TJ Barrier, promoting BTB function. These findings support the emerging concept that CAR is not only a structural protein, it is involved in conferring the phosphorylation status of other adhesion proteins at the BTB (e.g., occludin) possibly mediated via its structural interactions with nonreceptor protein kinases, thereby modulating endocytic vesicle-mediated protein trafficking.

  • Drug transporters and blood–testis Barrier function
    Journal of Endocrinology, 2011
    Co-Authors: Linlin Su, Dolores D. Mruk, C. Yan Cheng

    Abstract:

    The blood–testis Barrier (BTB) creates an immunological Barrier that segregates the seminiferous epithelium into the basal and apical compartment. Thus, meiosis I/II and postmeiotic germ cell development take place in a specialized microenvironment in the apical compartment behind the BTB and these events are being shielded from the host immune system. If unwanted drugs and/or chemicals enter the apical compartment from the microvessels in the interstitium via the basal compartment, efflux pumps (e.g. P-glycoprotein) located in Sertoli cells and/or spermatids can actively transport these molecules out of the apical compartment. However, the mechanism(s) by which influx pumps regulate the entry of drugs/chemicals into the apical compartment is not known. In this study, a solute carrier (SLC) transporter organic anion transporting polypeptide 3 (Oatp3, Slco1a5) was shown to be an integrated component of the N-cadherin-based adhesion complex at the BTB. However, a knockdown of Oatp3 alone or in combination with three other major Sertoli cell drug influx pumps, namely Slc22a5, Slco6b1, and Slco6c1, by RNAi using corresponding specific siRNA duplexes failed to perturb the Sertoli cell tight junction (TJ) permeability Barrier function. Yet, the transport of [ 3 H]adjudin, a potential male contraceptive that is considered a toxicant to spermatogenesis, across the BTB was impeded following the knockdown of either Oatp3 or all the four SLC transporters. In short, even though drug transporters (e.g. influx pumps) are integrated components of the adhesion protein complexes at the BTB, they are not involved in regulating the Sertoli cell TJ permeability Barrier function, instead they are only involved in the transport of drugs, such as adjudin, across the immunological Barrier at the BTB.