Myosin VIIa Supports Spermatid/Organelle Transport and Cell Adhesion During Spermatogenesis in the Rat Testis.

The biology of transport of spermatids and spermatid adhesion across the seminiferous epithelium during the epithelial cycle remains largely unexplored. Nonetheless, studies have implicated the role of motor proteins in these cellular events. In this article, we report findings to unravel the role of myosin VIIa, an F-actin-based barbed (+)-end-directed motor protein, to support cellular transport and adhesion in the testis.

Dynein 1 supports spermatid transport and spermiation during spermatogenesis in the rat testis.

In the mammalian testis, spermatogenesis is dependent on the microtubule (MT)-specific motor proteins, such as dynein 1, that serve as the engine to support germ cell and organelle transport across the seminiferous epithelium at different stages of the epithelial cycle. Yet the underlying molecular mechanism(s) that support this series of cellular events remain unknown. Herein, we used RNAi to knockdown cytoplasmic dynein 1 heavy chain (Dync1h1) and an inhibitor ciliobrevin D to inactivate dynein in Sertoli cells in vitro and the testis in vivo, thereby probing the role of dynein 1 in spermatogenesis.

Vangl2 regulates spermatid planar cell polarity through microtubule (MT)-based cytoskeleton in the rat testis.

During spermatogenesis, developing elongating/elongated spermatids are highly polarized cells, displaying unique apico-basal polarity. For instance, the heads of spermatids align perpendicular to the basement membrane with their tails pointing to the tubule lumen. Thus, the maximal number of spermatids are packed within the limited space of the seminiferous epithelium to support spermatogenesis.

Monitoring the Integrity of the Blood-Testis Barrier (BTB): An In Vivo Assay.

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.

Regulation of Blood-Testis Barrier (BTB) Dynamics, Role of Actin-, and Microtubule-Based Cytoskeletons.

The blood-testis barrier (BTB) is an important ultrastructure in the testis that supports meiosis and postmeiotic spermatid development since a delay in the establishment of a functional Sertoli cell barrier during postnatal development in rats or mice by 17-20 day postpartum (dpp) would lead to a delay of the first wave of meiosis. Furthermore, irreversible disruption of the BTB by toxicants also induces infertility in rodents. Herein, we summarize recent findings that BTB dynamics (i.

Actin nucleator Spire 1 is a regulator of ectoplasmic specialization in the testis.

Germ cell differentiation during the epithelial cycle of spermatogenesis is accompanied by extensive remodeling at the Sertoli cell-cell and Sertoli cell-spermatid interface to accommodate the transport of preleptotene spermatocytes and developing spermatids across the blood-testis barrier (BTB) and the adluminal compartment of the seminiferous epithelium, respectively. The unique cell junction in the testis is the actin-rich ectoplasmic specialization (ES) designated basal ES at the Sertoli cell-cell interface, and the apical ES at the Sertoli-spermatid interface. Since ES dynamics (i.

Rescue of PFOS-induced human Sertoli cell injury by overexpressing a p-FAK-Y407E phosphomimetic mutant.

Unlabelled: PFOS induces Sertoli cell injury using testicular cells isolated from rodent testes, but it remains unknown if PFOS has similar effects in humans. Herein, we maintained human Sertoli cells in a mitotically active state in vitro, thus enabling transfection experiments that altered gene expression to explore the molecular mechanism(s) underlying toxicant-induced cell injury. Human Sertoli cells obtained from men at ages 15, 23, 36 and 40 were cultured in vitro.

mTORC1/rpS6 regulates blood-testis barrier dynamics and spermatogenetic function in the testis in vivo.

The blood-testis barrier (BTB), conferred by Sertoli cells in the mammalian testis, is an important ultrastructure that supports spermatogenesis. Studies using animal models have shown that a disruption of the BTB leads to meiotic arrest, causing defects in spermatogenesis and male infertility. To better understand the regulation of BTB dynamics, we report findings herein to understand the role of ribosomal protein S6 (rpS6), a downstream signaling protein of mammalian target of rapamycin complex 1 (mTORC1), in promoting BTB disruption in the testis in vivo, making the barrier "leaky.

Cell polarity and cytoskeletons-Lesson from the testis.

Cell polarity in the adult mammalian testis refers to the polarized alignment of developing spermatids during spermiogenesis and the polarized organization of organelles (e.g., phagosomes, endocytic vesicles, Sertoli cell nuclei, Golgi apparatus) in Sertoli cells and germ cells to support spermatogenesis.

Cell polarity and planar cell polarity (PCP) in spermatogenesis.

In adult mammalian testes, spermatids, most notably step 17-19 spermatids in stage IV-VIII tubules, are aligned with their heads pointing toward the basement membrane and their tails toward the tubule lumen. On the other hand, these polarized spermatids also align across the plane of seminiferous epithelium, mimicking planar cell polarity (PCP) found in other hair cells in cochlea (inner ear). This orderly alignment of developing spermatids during spermiogenesis is important to support spermatogenesis, such that the maximal number of developing spermatids can be packed and supported by a fixed population of differentiated Sertoli cells in the limited space of the seminiferous epithelium in adult testes.

Abcb1a and Abcb1b genes function differentially in blood-testis barrier dynamics in the rat.

During spermatogenesis, immature spermatocytes traverse the blood-testis barrier (BTB) and enter the apical apartment of seminiferous epithelium for further development. This course involves extensive junction disassembly and reassembly at the BTB. P-glycoprotein is known to be coded by two genes in rodents, namely Abcb1a and Abcb1b.

Erratum: Perfluorooctanesulfonate (PFOS)-induced Sertoli cell injury through a disruption of F-actin and microtubule organization is mediated by Akt1/2.

A correction to this article has been published and is linked from the HTML version of this paper. The error has been fixed in the paper.

Regulation of spermatogenesis by a local functional axis in the testis: role of the basement membrane-derived noncollagenous 1 domain peptide.

Spermatogenesis takes place in the epithelium of the seminiferous tubules of the testes, producing millions of spermatozoa per day in an adult male in rodents and humans. Thus, multiple cellular events that are regulated by an array of signaling molecules and pathways are tightly coordinated to support spermatogenesis. Here, we report findings of a local regulatory axis between the basement membrane (BM), the blood-testis barrier (BTB), and the apical ectoplasmic specialization (apical ES; a testis-specific, actin-rich adherens junction at the Sertoli cell-spermatid interface) to coordinate cellular events across the seminiferous epithelium during the epithelial cycle.

Signaling pathways regulating blood-tissue barriers - Lesson from the testis.

Signaling pathways that regulate blood-tissue barriers are important for studying the biology of various blood-tissue barriers. This information, if deciphered and better understood, will provide better therapeutic management of diseases particularly in organs that are sealed by the corresponding blood-tissue barriers from systemic circulation, such as the brain and the testis. These barriers block the access of antibiotics and/or chemotherapeutical agents across the corresponding barriers.

Perfluorooctanesulfonate (PFOS)-induced Sertoli cell injury through a disruption of F-actin and microtubule organization is mediated by Akt1/2.

PFOS (perfluorooctanesulfonate, or perfluorooctane sulfonic acid) is an anthropogenic fluorosurfactant widely used in consumer products. While its use in Europe, Canada and the U.S.

Basement Membrane Laminin α2 Regulation of BTB Dynamics via Its Effects on F-Actin and Microtubule Cytoskeletons Is Mediated Through mTORC1 Signaling.

A local axis connects the apical ectoplasmic specialization (ES) at the Sertoli-spermatid interface, the basal ES at the blood-testis barrier (BTB), and the basement membrane across the seminiferous epithelium functionally in rat testes. As such, cellular events that take place simultaneously across the epithelium such as spermiation and BTB remodeling that occur at the apical ES and the basal ES, respectively, at stage VIII of the cycle are coordinated. Herein, laminin α2, a structural component of the basement membrane, was found to regulate BTB dynamics.

Regulation of the blood-testis barrier by a local axis in the testis: role of laminin α2 in the basement membrane.

Laminin α2 is one of the constituent components of the basement membrane (BM) in adult rat testes. Earlier studies that used a mouse genetic model have shown that a deletion of laminin α2 impedes male fertility by disrupting ectoplasmic specialization (ES; a testis-specific, actin-rich anchoring junction) function along the length of Sertoli cell in the testis. This includes ES at the Sertoli cell-elongating/elongated spermatid interface, which is known as apical ES and possibly the Sertoli-Sertoli cell interface, known as basal ES, at the blood-testis barrier (BTB).

F5-peptide induces aspermatogenesis by disrupting organization of actin- and microtubule-based cytoskeletons in the testis.

During the release of sperm at spermiation, a biologically active F5-peptide, which can disrupt the Sertoli cell tight junction (TJ) permeability barrier, is produced at the site of the degenerating apical ES (ectoplasmic specialization). This peptide coordinates the events of spermiation and blood-testis barrier (BTB) remodeling at stage VIII of the epithelial cycle, creating a local apical ES-BTB axis to coordinate cellular events across the epithelium. The mechanism(s) by which F5-peptide perturbs BTB restructuring, and its involvement in apical ES dynamics remain unknown.

Overexpression of plastin 3 in Sertoli cells disrupts actin microfilament bundle homeostasis and perturbs the tight junction barrier.

Throughout the epithelial cycle of spermatogenesis, actin microfilaments arranged as bundles near the Sertoli cell plasma membrane at the Sertoli cell-cell interface that constitute the blood-testis barrier (BTB) undergo extensive re-organization by converting between bundled and unbundled/branched configuration to give plasticity to the F-actin network. This is crucial to accommodate the transport of preleptotene spermatocytes across the BTB. Herein, we sought to examine changes in the actin microfilament organization at the Sertoli cell BTB using an in vitro model since Sertoli cells cultured in vitro is known to establish a functional tight junction (TJ)-permeability barrier that mimics the BTB in vivo.

Rescue of perfluorooctanesulfonate (PFOS)-mediated Sertoli cell injury by overexpression of gap junction protein connexin 43.

Perfluorooctanesulfonate (PFOS) is an environmental toxicant used in developing countries, including China, as a stain repellent for clothing, carpets and draperies, but it has been banned in the U.S. and Canada since the late 2000s.

Polarity protein Crumbs homolog-3 (CRB3) regulates ectoplasmic specialization dynamics through its action on F-actin organization in Sertoli cells.

Crumbs homolog 3 (or Crumbs3, CRB3) is a polarity protein expressed by Sertoli and germ cells at the basal compartment in the seminiferous epithelium. CRB3 also expressed at the blood-testis barrier (BTB), co-localized with F-actin, TJ proteins occludin/ZO-1 and basal ES (ectoplasmic specialization) proteins N-cadherin/β-catenin at stages IV-VII only. The binding partners of CRB3 in the testis were the branched actin polymerization protein Arp3, and the barbed end-capping and bundling protein Eps8, illustrating its possible role in actin organization.

Cell polarity proteins and spermatogenesis.

When the cross-section of a seminiferous tubule from an adult rat testes is examined microscopically, Sertoli cells and germ cells in the seminiferous epithelium are notably polarized cells. For instance, Sertoli cell nuclei are found near the basement membrane. On the other hand, tight junction (TJ), basal ectoplasmic specialization (basal ES, a testis-specific actin-rich anchoring junction), gap junction (GJ) and desmosome that constitute the blood-testis barrier (BTB) are also located near the basement membrane.

Formin 1 Regulates Microtubule and F-Actin Organization to Support Spermatid Transport During Spermatogenesis in the Rat Testis.

Formin 1 confers actin nucleation by generating long stretches of actin microfilaments to support cell movement, cell shape, and intracellular protein trafficking. Formin 1 is likely involved in microtubule (MT) dynamics due to the presence of a MT binding domain near its N terminus. Here, formin 1 was shown to structurally interact with α-tubulin, the building block of MT, and also end-binding protein 1 (a MT plus [+]-end-binding protein that stabilizes MT) in the testis.

Planar Cell Polarity (PCP) Protein Vangl2 Regulates Ectoplasmic Specialization Dynamics via Its Effects on Actin Microfilaments in the Testes of Male Rats.

Planar cell polarity (PCP) proteins confer polarization of a field of cells (eg, elongating/elongated spermatids) within the plane of an epithelium such as the seminiferous epithelium of the tubule during spermatogenesis. In adult rat testes, Sertoli and germ cells were found to express PCP core proteins (eg, Van Gogh-like 2 [Vangl2]), effectors, ligands, and signaling proteins. Vangl2 expressed predominantly by Sertoli cells was localized at the testis-specific, actin-rich ectoplasmic specialization (ES) at the Sertoli-spermatid interface in the adluminal compartment and also Sertoli-Sertoli interface at the blood-testis barrier (BTB) and structurally interacted with actin, N-cadherin, and another PCP/polarity protein Scribble.

Coordination of Actin- and Microtubule-Based Cytoskeletons Supports Transport of Spermatids and Residual Bodies/Phagosomes During Spermatogenesis in the Rat Testis.

Germ cell transport across the seminiferous epithelium during spermatogenesis requires the intricate coordination of cell junctions, signaling proteins, and both actin- and microtubule (MT)-based cytoskeletons. Although the involvement of cytoskeletons in germ cell transport has been suggested, the precise mechanism(s) remains elusive. Based on growing evidence that actin and MT interactions underlie fundamental cellular processes, such as cell motility, it is unlikely that actin- and MT-based cytoskeletons work independently to regulate germ cell transport in the testis.