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Toocheck C, Clister T, Shupe J, Crum C, Ravindranathan P, Lee TK, Ahn JM, Raj GV, Sukhwani M, Orwig KE, Walker WH. Mouse Spermatogenesis Requires Classical and Nonclassical Testosterone Signaling. Biol Reprod 2015; 94:11. [PMID: 26607719 PMCID: PMC4809556 DOI: 10.1095/biolreprod.115.132068] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 11/16/2015] [Indexed: 01/12/2023] Open
Abstract
Testosterone acts though the androgen receptor in Sertoli cells to support germ cell development (spermatogenesis) and male fertility, but the molecular and cellular mechanisms by which testosterone acts are not well understood. Previously, we found that in addition to acting through androgen receptor to directly regulate gene expression (classical testosterone signaling pathway), testosterone acts through a nonclassical pathway via the androgen receptor to rapidly activate kinases that are known to regulate spermatogenesis. In this study, we provide the first evidence that nonclassical testosterone signaling occurs in vivo as the MAP kinase cascade is rapidly activated in Sertoli cells within the testis by increasing testosterone levels in the rat. We find that either classical or nonclassical signaling regulates testosterone-mediated Rhox5 gene expression in Sertoli cells within testis explants. The selective activation of classical or nonclassical signaling pathways in Sertoli cells within testis explants also resulted in the differential activation of the Zbtb16 and c-Kit genes in adjacent spermatogonia germ cells. Delivery of an inhibitor of either pathway to Sertoli cells of mouse testes disrupted the blood-testis barrier that is essential for spermatogenesis. Furthermore, an inhibitor of nonclassical testosterone signaling blocked meiosis in pubertal mice and caused the loss of meiotic and postmeiotic germ cells in adult mouse testes. An inhibitor of the classical pathway caused the premature release of immature germ cells. Collectively, these observations indicate that classical and nonclassical testosterone signaling regulate overlapping and distinct functions that are required for the maintenance of spermatogenesis and male fertility.
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Affiliation(s)
- Corey Toocheck
- Center for Research in Reproductive Physiology, Department of Obstetrics, Gynecology, and Reproductive Sciences, Magee Womens Research Institute, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Terri Clister
- Center for Research in Reproductive Physiology, Department of Obstetrics, Gynecology, and Reproductive Sciences, Magee Womens Research Institute, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - John Shupe
- Center for Research in Reproductive Physiology, Department of Obstetrics, Gynecology, and Reproductive Sciences, Magee Womens Research Institute, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Chelsea Crum
- Center for Research in Reproductive Physiology, Department of Obstetrics, Gynecology, and Reproductive Sciences, Magee Womens Research Institute, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Preethi Ravindranathan
- Department of Urology, University of Texas, Southwestern Medical Center at Dallas, Dallas, Texas
| | - Tae-Kyung Lee
- Department of Chemistry, University of Texas, Dallas, Richardson, Texas
| | - Jung-Mo Ahn
- Department of Chemistry, University of Texas, Dallas, Richardson, Texas
| | - Ganesh V Raj
- Department of Urology, University of Texas, Southwestern Medical Center at Dallas, Dallas, Texas
| | - Meena Sukhwani
- Center for Research in Reproductive Physiology, Department of Obstetrics, Gynecology, and Reproductive Sciences, Magee Womens Research Institute, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Kyle E Orwig
- Center for Research in Reproductive Physiology, Department of Obstetrics, Gynecology, and Reproductive Sciences, Magee Womens Research Institute, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - William H Walker
- Center for Research in Reproductive Physiology, Department of Obstetrics, Gynecology, and Reproductive Sciences, Magee Womens Research Institute, University of Pittsburgh, Pittsburgh, Pennsylvania
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52
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Nakamura S, Maehara T, Watanabe S, Ishihara M, Sato M. Liver lobe and strain difference in gene expression after hydrodynamics-based gene delivery in mice. Anim Biotechnol 2015; 26:51-7. [PMID: 25153456 DOI: 10.1080/10495398.2014.886583] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Hydrodynamics-based gene delivery (HGD) is a widely recognized technique for delivering exogenous DNA with high efficiency to murine hepatocytes. In this study, we investigated stimulation of exogenous DNA uptake and expression using a commercially available reagent for HGD. We also examined which mouse strain and mouse liver lobe would achieve the best gene delivery performance. Mice were injected with a solution containing reporter plasmid DNA or DNA and a gene delivery reagent. One day after the HGD procedure, liver samples were isolated and subjected to biochemical and histochemical analyses. The reporter plasmid DNA showed the strongest signal when the DNA was dissolved in TransIT-EE Hydrodynamic Delivery Solution (Takara Bio Inc., Shiga, Japan). Evaluation of transgene expression in each hepatic lobe in ICR, C57BL/6N, Balb/cA, and B6C3F1 mice showed that ICR mice exhibited the best gene transfer and that the right median lobe had the highest level of transgene expression. These findings suggest the importance of choice in mouse strains and liver lobes when performing gene-based manipulations of the liver.
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Affiliation(s)
- Shingo Nakamura
- a Department of Surgery II , National Defense Medical College , Saitama , Japan
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53
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Mok KW, Chen H, Lee WM, Cheng CY. rpS6 regulates blood-testis barrier dynamics through Arp3-mediated actin microfilament organization in rat sertoli cells. An in vitro study. Endocrinology 2015; 156:1900-13. [PMID: 25714812 PMCID: PMC4398761 DOI: 10.1210/en.2014-1791] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
In the seminiferous epithelium of rat testes, preleptotene spermatocytes residing in the basal compartment are transported across the blood-testis barrier (BTB) to enter the adluminal compartment at stage VIII of the epithelial cycle. This process involves redistribution of tight junction (TJ) proteins via reorganization of actin cytoskeleton in Sertoli cells that serves as attachment site for adhesion protein complexes. Ribosomal protein S6 (rpS6), a downstream molecule of mTORC1 (mammalian target of rapamycin complex 1), participates in this process via a yet-to-be defined mechanism. Here, we constructed an rpS6 quadruple phosphomimetic mutant by converting Ser residues at 235, 236, 240, and 244 to Glu via site-directed mutagenesis, making this mutant constitutively active. When this rpS6 mutant was overexpressed in Sertoli cells cultured in vitro with an established TJ barrier mimicking the BTB in vivo, it perturbed the TJ permeability by down-regulating and redistributing TJ proteins at the cell-cell interface. These changes are mediated by a reorganization of actin microfilaments, which was triggered by a redistribution of activated actin-related protein 3 (Arp3) as well as changes in Arp3-neuronal Wiskott-Aldrich Syndrome protein (N-WASP) interaction. This in turn induced reorganization of actin microfilaments, converting them from a "bundled" to an "unbundled/branched" configuration, concomitant with a reduced actin bundling activity, thereby destabilizing the TJ-barrier function. These changes were mediated by Akt (transforming oncogene of v-akt), because an Akt knockdown by RNA interference was able to mimic the phenotypes of rpS6 mutant overexpression at the Sertoli cell BTB. In summary, this study illustrates a mechanism by which mTORC1 signal complex regulates BTB function through rpS6 downstream by modulating actin organization via the Arp2/3 complex, which may be applicable to other tissue barriers.
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Affiliation(s)
- Ka-Wai Mok
- The Mary M. Wohlford Laboratory for Male Contraceptive Research (K.-W.M., H.C., C.Y.C.), Center for Biomedical Research, Population Council, New York, New York 10065; and School of Biological Sciences (W.M.L.), University of Hong Kong, Hong Kong, China
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54
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ErLin S, WenJie W, LiNing W, BingXin L, MingDe L, Yan S, RuiFa H. Musashi-1 maintains blood-testis barrier structure during spermatogenesis and regulates stress granule formation upon heat stress. Mol Biol Cell 2015; 26:1947-56. [PMID: 25717188 PMCID: PMC4436837 DOI: 10.1091/mbc.e14-11-1497] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 02/18/2015] [Indexed: 12/26/2022] Open
Abstract
Msi-1 knockdown disrupts blood-testis barrier structure and the continuous process of spermatogenesis. A role for Msi-1 in regulating Sertoli cell fate following heat-induced injury is noted. In mouse testes, Musashi-1 (Msi-1) was predominantly expressed in the cytoplasm and nuclei of Sertoli cells. Here we demonstrate that knockdown of Msi-1 in Sertoli cells altered the levels and distribution of blood–testis barrier (BTB)-associated proteins. Moreover, Msi-1 knockdown in vivo disrupted BTB functional structure and spermatogenesis. In addition, we report a novel role of Msi-1 in regulating Sertoli cells survival following heat-induced injury. Endogenous Msi-1 protein in heat-treated Sertoli cells was recruited to stress granules. The formation of stress granules was considerably disrupted, and apoptosis was significantly up-regulated in Msi-1–knockdown Sertoli cells after heat treatment. p-ERK1/2 acted downstream of stress granule formation, and inhibition of p-ERK1/2 signaling triggered Sertoli cell apoptosis upon heat stress. In conclusion, we demonstrate that Msi-1 is critical for constructing a functional BTB structure and maintaining spermatogenesis. We also note a role for Msi-1 in regulating Sertoli cell fate following heat-induced injury, likely through the induction of stress granule formation and subsequent activation of p-ERK1/2 signaling.
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Affiliation(s)
- Sun ErLin
- Department of Urology, Tianjin Institute of Urology, Second Hospital of Tianjin Medical University, Tianjin 300211, People's Republic of China
| | - Wei WenJie
- Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, PA 19104 Department of Urology, Second Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325027, People's Republic of China
| | - Wang LiNing
- Department of Urology, Tianjin Institute of Urology, Second Hospital of Tianjin Medical University, Tianjin 300211, People's Republic of China
| | - Lu BingXin
- Department of Urology, Tianjin Institute of Urology, Second Hospital of Tianjin Medical University, Tianjin 300211, People's Republic of China
| | - Lei MingDe
- Department of Urology, Tianjin Institute of Urology, Second Hospital of Tianjin Medical University, Tianjin 300211, People's Republic of China
| | - Sun Yan
- Department of Urology, Tianjin Institute of Urology, Second Hospital of Tianjin Medical University, Tianjin 300211, People's Republic of China
| | - Han RuiFa
- Department of Urology, Tianjin Institute of Urology, Second Hospital of Tianjin Medical University, Tianjin 300211, People's Republic of China
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55
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Xiao H, Wang H, Silva EA, Thompson J, Guillou A, Yates JR, Buchon N, Franc NC. The Pallbearer E3 ligase promotes actin remodeling via RAC in efferocytosis by degrading the ribosomal protein S6. Dev Cell 2014; 32:19-30. [PMID: 25533207 DOI: 10.1016/j.devcel.2014.11.015] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2014] [Revised: 10/06/2014] [Accepted: 11/10/2014] [Indexed: 01/24/2023]
Abstract
Clearance of apoptotic cells (efferocytosis) is achieved through phagocytosis by professional or amateur phagocytes. It is critical for tissue homeostasis and remodeling in all animals. Failure in this process can contribute to the development of inflammatory autoimmune or neurodegenerative diseases. We found previously that the PALL-SCF E3-ubiquitin ligase complex promotes apoptotic cell clearance, but it remained unclear how it did so. Here we show that the F-box protein PALL interacts with phosphorylated ribosomal protein S6 (RpS6) to promote its ubiquitylation and proteasomal degradation. This leads to RAC2 GTPase upregulation and activation and F-actin remodeling that promotes efferocytosis. We further show that the specific role of PALL in efferocytosis is driven by its apoptotic cell-induced nuclear export. Finding a role for RpS6 in the negative regulation of efferocytosis provides the opportunity to develop new strategies to regulate this process.
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Affiliation(s)
- Hui Xiao
- Department of Immunology and Microbial Science and Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Hui Wang
- Department of Immunology and Microbial Science and Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Elizabeth A Silva
- Medical Research Council Laboratory for Molecular Cell Biology, London WC1E 6BT, UK
| | - James Thompson
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Aurélien Guillou
- Department of Entomology, Cornell University, Ithaca, NY 14853, USA
| | - John R Yates
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Nicolas Buchon
- Department of Entomology, Cornell University, Ithaca, NY 14853, USA
| | - Nathalie C Franc
- Department of Immunology and Microbial Science and Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA; Medical Research Council Laboratory for Molecular Cell Biology, London WC1E 6BT, UK.
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56
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Mok KW, Mruk DD, Cheng CY. rpS6 regulates blood-testis barrier dynamics through Akt-mediated effects on MMP-9. J Cell Sci 2014; 127:4870-82. [PMID: 25217631 DOI: 10.1242/jcs.152231] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Mammalian target of rapamycin complex 1 (mTORC1) is an emerging regulator of blood-tissue barriers that utilizes ribosomal protein S6 (rpS6) as the downstream signaling molecule. To explore the role of rpS6 in blood-testis barrier (BTB) function, a constitutively active quadruple rpS6 phosphomimetic mutant was constructed in mammalian expression vector and overexpressed in Sertoli cells cultured in vitro that mimicked the BTB in vivo. Using this quadruple phosphomimetic mutant, phosphorylated (p)-rpS6 was shown to disrupt IGF-1/insulin signaling, thereby abolishing Akt phosphorylation, which led to an induction of MMP-9. This increase in MMP-9 secretion perturbed the Sertoli cell tight junction permeability barrier by proteolysis-mediated downregulation of tight junction proteins at the BTB. These findings were confirmed by the use of a specific MMP-9 inhibitor that blocked the disruption of the tight junction permeability barrier by the rpS6 mutant. Additionally, RNA interference (RNAi)-mediated Akt silencing was able to mimic the results of rpS6 mutant overexpression in Sertoli cells, further confirming this p-rpS6-Akt-MMP-9 signaling pathway. In conclusion, these data support a new concept of mTORC1-mediated BTB regulation, that is possibly also applicable to other blood-tissue barriers.
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Affiliation(s)
- Ka-Wai Mok
- The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, 1230 York Avenue, New York, NY 10065, USA
| | - Dolores D Mruk
- The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, 1230 York Avenue, New York, NY 10065, USA
| | - C Yan Cheng
- The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, 1230 York Avenue, New York, NY 10065, USA
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57
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Oliveira PF, Martins AD, Moreira AC, Cheng CY, Alves MG. The Warburg effect revisited--lesson from the Sertoli cell. Med Res Rev 2014; 35:126-51. [PMID: 25043918 DOI: 10.1002/med.21325] [Citation(s) in RCA: 125] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Otto Warburg observed that cancerous cells prefer fermentative instead of oxidative metabolism of glucose, although the former is in theory less efficient. Since Warburg's pioneering works, special attention has been given to this difference in cell metabolism. The Warburg effect has been implicated in cell transformation, immortalization, and proliferation during tumorigenesis. Cancer cells display enhanced glycolytic activity, which is correlated with high proliferation, and thus, glycolysis appears to be an excellent candidate to target cancer cells. Nevertheless, little attention has been given to noncancerous cells that exhibit a "Warburg-like" metabolism with slight, but perhaps crucial, alterations that may provide new directions to develop new and effective anticancer therapies. Within the testis, the somatic Sertoli cell (SC) presents several common metabolic features analogous to cancer cells, and a clear "Warburg-like" metabolism. Nevertheless, SCs actively proliferate only during a specific time period, ceasing to divide in most species after puberty, when they become terminally differentiated. The special metabolic features of SC, as well as progression from the immature but proliferative state, to the mature nonproliferative state, where a high glycolytic activity is maintained, make these cells unique and a good model to discuss new perspectives on the Warburg effect. Herein we provide new insight on how the somatic SC may be a source of new and exciting information concerning the Warburg effect and cell proliferation.
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Affiliation(s)
- Pedro F Oliveira
- CICS-UBI, Health Sciences Research Centre, University of Beira Interior, Covilhã, Portugal
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58
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Cheng CY, Lie PPY, Wong EWP, Mruk DD. Focal adhesion kinase and actin regulatory/binding proteins that modulate F-actin organization at the tissue barrier: Lesson from the testis. Tissue Barriers 2014; 1:e24252. [PMID: 24665388 PMCID: PMC3875635 DOI: 10.4161/tisb.24252] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Revised: 03/07/2013] [Accepted: 03/09/2013] [Indexed: 11/28/2022] Open
Abstract
Focal adhesion kinase (FAK), as its name implied, is an important mediator of integrin-based signaling function in mammalian cells at the focal adhesion complex (FAC, also known as focal contact) at the cell-extracellular matrix interface. FAK is intimately related to cell movement, such as in macrophages, fibroblasts and also tumor cells. In the testis, however, FAK and two of its phosphorylated forms, p-FAK-Tyr407 and -Tyr397, are not found at the FAC since there is no ultrastructure analogous or similar to FAC in the mammalian testis vs. other epithelia. Instead, FAK and its two phosphorylated forms are detected along the seminiferous epithelium in the rat testis at the cell-cell interface in a testis-specific adherens junction (AJ) known as the ectoplasmic specialization (ES). ES is an F-actin-rich ultrastructure in which bundles of actin filaments are sandwiched in-between plasma membrane and cisternae of endoplasmic reticulum not found in other mammalian epithelial/endothelial cells. The ES is restricted to the interface of Sertoli cells and spermatids (step 8–19) known as the apical ES, and to the Sertoli cell-cell interface known as the basal ES. Interestingly, the basal ES is also an integrated component of the blood-testis barrier (BTB), coexisting with tight junction (TJ) and gap junction (GJ), and it is conceivable that actin filament bundles at the ES undergo extensive organization, converting from their “bundled” to “de-bundled/branching” configuration to facilitate transport of germ cells across the epithelium and at the BTB during the epithelial cycle. A recent report (Lie et al. PNAS 109:12562–12567, 2012) has demonstrated that the stage-specific and spatiotemporal expression of p-FAK-Tyr407 and -Tyr397 are crucial to the regulation of these events via their stage-specific and spatiotemporal expression during the epithelial cycle mediated by their effects on the organization of the actin filament bundles at the ES, involving actin binding/regulatory proteins. In this Commentary, we will critically evaluate these findings in light of other recent reports in the field. While these ideas are based on studies in the BTB in the rat testis, this information should be applicable and helpful to investigators studying other tissue barriers.
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Affiliation(s)
- C Yan Cheng
- The Mary M. Wohlford Laboratory for Male Contraceptive Research; Center for Biomedical Research; Population Council; New York, NY USA
| | - Pearl P Y Lie
- The Mary M. Wohlford Laboratory for Male Contraceptive Research; Center for Biomedical Research; Population Council; New York, NY USA
| | - Elissa W P Wong
- The Mary M. Wohlford Laboratory for Male Contraceptive Research; Center for Biomedical Research; Population Council; New York, NY USA
| | - Dolores D Mruk
- The Mary M. Wohlford Laboratory for Male Contraceptive Research; Center for Biomedical Research; Population Council; New York, NY USA
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59
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Mok KW, Mruk DD, Cheng CY. Regulation of blood-testis barrier (BTB) dynamics during spermatogenesis via the "Yin" and "Yang" effects of mammalian target of rapamycin complex 1 (mTORC1) and mTORC2. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 301:291-358. [PMID: 23317821 DOI: 10.1016/b978-0-12-407704-1.00006-3] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In mammalian testes, haploid spermatozoa are formed from diploid spermatogonia during spermatogenesis, which is a complicated cellular process. While these cellular events were reported in the 1960s and 1970s, the underlying molecular mechanism(s) that regulates these events remained unexplored until the past ∼10 years. For instance, adhesion proteins were shown to be integrated components at the Sertoli cell-cell interface and/or the Sertoli-spermatid interface in the late 1980s. But only until recently, studies have demonstrated that some of the adhesion proteins serve as the platform for signal transduction that regulates cell adhesion. In this chapter, a brief summary and critical discussion are provided on the latest findings regarding these cell-adhesion proteins in the testis and their relationship to spermatogenesis. Moreover, antagonistic effects of two mammalian target of rapamycin (mTOR) complexes, known as mTORC1 and mTORC2, on cell-adhesion function in the testis are discussed. Finally, a hypothetic model is presented to depict how these two mTOR-signaling complexes having the "yin" and "yang" antagonistic effects on the Sertoli cell tight junction (TJ)-permeability barrier can maintain the blood-testis barrier (BTB) integrity during the epithelial cycle while preleptotene spermatocytes are crossing the BTB.
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Affiliation(s)
- Ka Wai Mok
- Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, New York, USA
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60
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Wan HT, Mruk DD, Li SYT, Mok KW, Lee WM, Wong CKC, Cheng CY. p-FAK-Tyr(397) regulates spermatid adhesion in the rat testis via its effects on F-actin organization at the ectoplasmic specialization. Am J Physiol Endocrinol Metab 2013; 305:E687-99. [PMID: 23880313 PMCID: PMC4073987 DOI: 10.1152/ajpendo.00254.2013] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
During spermatogenesis, the molecular mechanism that confers spermatid adhesion to the Sertoli cell at the apical ectoplasmic specialization (apical ES), a testis-specific F-actin-rich adherens junction, in the rat testis remains elusive. Herein, the activated form of focal adhesion kinase (FAK), p-FAK-Tyr(397), a component of the apical ES that was expressed predominantly and stage specifically in stage VII-early stage VIII tubules, was found to be a crucial apical ES regulator. Using an FAK-Y397E phosphomimetic mutant cloned in a mammalian expression vector for its transfection vs. FAK and vector alone in adult rat testes in vivo, its overexpression was found to cause defects in spermiation. These defects in spermiation were manifested by entrapment of spermatids in the seminiferous epithelium in late stage VIII-X tubules and were mediated by a disruption on the spatiotemporal expression and/or mislocalization of actin regulatory protein actin-related protein 3, which induces branched actin polymerization, epidermal growth factor receptor pathway substrate 8 (an actin barbed end capping and bundling protein), and palladin (an actin cross-linking and bundling protein). This thus perturbed changes of F-actin organization at the apical ES to facilitate spermiation, which also led to a concomitant alteration in the distribution and upregulation of adhesion proteins nectin-2 and nectin-3 at the apical ES. As such, nectin-2 and -3 remained at the apical ES to anchor step 19 spermatids on to the epithelium, delaying spermiation. These findings illustrate a mechanistic pathway mediated by p-FAK-Tyr(397) that regulates spermatid adhesion at the apical ES in vivo.
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Affiliation(s)
- Hin-Ting Wan
- 1The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, New York, New York;
| | - Dolores D. Mruk
- 1The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, New York, New York;
| | - Stephen Y. T. Li
- 1The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, New York, New York;
| | - Ka-Wai Mok
- 1The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, New York, New York;
| | - Will M. Lee
- 2School of Biological of Sciences, University of Hong Kong, Hong Kong, China; and
| | - Chris K. C. Wong
- 3Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - C. Yan Cheng
- 1The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, New York, New York;
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61
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Acharya KD, Veney SL. Sexually dimorphic expression and estradiol mediated up-regulation of a sex-linked ribosomal gene, RPS6, in the zebra finch brain. Dev Neurobiol 2013; 73:599-608. [PMID: 23554148 DOI: 10.1002/dneu.22085] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Revised: 03/12/2013] [Accepted: 03/26/2013] [Indexed: 12/24/2022]
Abstract
Sex-linked genes are considered to be a major contributor to neural sex differences in zebra finches. While several candidates have been identified, additional ones are continuously being discovered. Here we report on a novel Z-linked ribosomal gene (rpS6) that is enhanced in the male brain as compared to the female's throughout life. In both sexes, expression of rpS6 is highest at P3 and P8 (just before the onset of morphologically detectable sex differences), decreases around P15, and then remains decreased through adulthood. Analysis of rpS6 mRNA revealed widespread distribution throughout the brain. However, within song regions HVC and RA, mRNA containing cells were greater in males as compared to females. Hormones are also involved in the development of neural dimorphisms, so we additionally investigated whether rpS6 might interact with estradiol (E2 ). An up-regulation of rpS6 gene was observed in both sexes following treatment with E2 and the effect was approximately twice as large in males as compared with females. These data suggest that rpS6 may be involved in sexual differentiation of the zebra finch brain, and that the effect is facilitated by E2 .
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Affiliation(s)
- Kalpana D Acharya
- School of Biomedical Sciences, Kent State University, Kent, OH 44242, USA
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62
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Qian X, Mruk DD, Wong EWP, Lie PPY, Cheng CY. Palladin is a regulator of actin filament bundles at the ectoplasmic specialization in adult rat testes. Endocrinology 2013; 154:1907-20. [PMID: 23546604 PMCID: PMC3628023 DOI: 10.1210/en.2012-2269] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In rat testes, the ectoplasmic specialization (ES) at the Sertoli-Sertoli and Sertoli-spermatid interface known as the basal ES at the blood-testis barrier and the apical ES in the adluminal compartment, respectively, is a testis-specific adherens junction. The remarkable ultrastructural feature of the ES is the actin filament bundles that sandwiched in between the cisternae of endoplasmic reticulum and apposing plasma membranes. Although these actin filament bundles undergo extensive reorganization to switch between their bundled and debundled state to facilitate blood-testis barrier restructuring and spermatid adhesion/transport, the regulatory molecules underlying these events remain unknown. Herein we report findings of an actin filament cross-linking/bundling protein palladin, which displayed restrictive spatiotemporal expression at the apical and the basal ES during the epithelial cycle. Palladin structurally interacted and colocalized with Eps8 (epidermal growth factor receptor pathway substrate 8, an actin barbed end capping and bundling protein) and Arp3 (actin related protein 3, which together with Arp2 form the Arp2/3 complex to induce branched actin nucleation, converting bundled actin filaments to an unbundled/branched network), illustrating its role in regulating actin filament bundle dynamics at the ES. A knockdown of palladin in Sertoli cells in vitro with an established tight junction (TJ)-permeability barrier was found to disrupt the TJ function, which was associated with a disorganization of actin filaments that affected protein distribution at the TJ. Its knockdown in vivo also perturbed F-actin organization that led to a loss of spermatid polarity and adhesion, causing defects in spermatid transport and spermiation. In summary, palladin is an actin filament regulator at the ES.
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Affiliation(s)
- Xiaojing Qian
- Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, 1230 York Ave, New York, New York 10065, USA
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Qian X, Mruk DD, Wong EWP, Cheng CY. Breast cancer resistance protein regulates apical ectoplasmic specialization dynamics stage specifically in the rat testis. Am J Physiol Endocrinol Metab 2013; 304:E757-69. [PMID: 23403943 PMCID: PMC3625752 DOI: 10.1152/ajpendo.00645.2012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Drug transporters determine the bioavailability of drugs in the testis behind the blood-testis barrier (BTB). Thus, they are crucial for male contraceptive development if these drugs (e.g., adjudin) exert their effects behind the BTB. Herein breast cancer resistance protein (Bcrp), an efflux drug transporter, was found to be expressed by both Sertoli and germ cells. Interestingly, Bcrp was not a component of the Sertoli cell BTB. Instead, it was highly expressed by peritubular myoid cells at the tunica propria and also endothelial cells of the microvessels in the interstitium at all stages of the epithelial cycle. Unexpectedly, Bcrp was found to be expressed at the Sertoli-step 18-19 spermatid interface but limited to stage VI-early VIII tubules, and an integrated component of the apical ectoplasmic specialization (apical ES). Apparently, Bcrp is being used by late-stage spermatids to safeguard their completion of spermiogenesis by preventing harmful drugs to enter these cells while they transform to spermatozoa. Also, the association of Bcrp with actin, Eps8 (epidermal growth factor receptor pathway substrate 8, an actin barbed end capping and bundling protein), and Arp3 (actin-related protein 3, a component of the Arp2/3 complex known to induce branched actin polymerization) at the apical ES suggest that Bcrp may be involved in regulating the organization of actin filament bundles at the site. Indeed, a knockdown of Bcrp by RNAi in the testis perturbed the apical ES function, disrupting spermatid polarity and adhesion. In summary, Bcrp is a regulator of the F-actin-rich apical ES in the testis.
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Affiliation(s)
- Xiaojing Qian
- 1The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, New York, New York;
- 2Department of Anatomy, Histology and Embryology, School of Basic Medicine, Peking Union Medical College, Beijing, China
| | - Dolores D. Mruk
- 1The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, New York, New York;
| | - Elissa W. P. Wong
- 1The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, New York, New York;
| | - C. Yan Cheng
- 1The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, New York, New York;
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64
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Abstract
The blood-testis barrier (BTB) is a large junctional complex composed of tight junctions, adherens junctions, and gap junctions between adjacent Sertoli cells in the seminiferous tubules of the testis. Maintenance of the BTB as well as the controlled disruption and reformation of the barrier is essential for spermatogenesis and male fertility. Tyrosine phosphorylation of BTB proteins is known to regulate the integrity of adherens and tight junctions found at the BTB. SHP2 is a nonreceptor protein tyrosine phosphatase (PTP) and a key regulator of growth factor-mediated tyrosine kinase signaling pathways. We found that SHP2 is localized to Sertoli-Sertoli cell junctions in rat testis. The overexpression of a constitutive active SHP2 mutant, SHP2 Q79R, up-regulated the BTB disruptor ERK1/2 via Src kinase in primary rat Sertoli cells in culture. Furthermore, focal adhesion kinase (FAK), which also supports BTB integrity, was found to interact with SHP2 and constitutive activation of SHP2 decreased FAK tyrosine phosphorylation. Expression of the SHP2 Q79R mutant in primary cultured Sertoli cells also resulted in the loss of tight junction and adherens junction integrity that corresponded with the disruption of the actin cytoskeleton and mislocalization of adherens junction and tight junction proteins N-cadherin, β-catenin, and ZO-1 away from the plasma membrane. These results suggest that SHP2 is a key regulator of BTB integrity and Sertoli cell support of spermatogenesis and fertility.
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Affiliation(s)
- Pawan Puri
- Center for Research in Reproductive Physiology, Department of Cell Biology and Molecular Physiology, Magee-Womens Research Institute, University of Pittsburgh, Pittsburgh, PA 15261, USA
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Su W, Mruk DD, Cheng CY. Regulation of actin dynamics and protein trafficking during spermatogenesis--insights into a complex process. Crit Rev Biochem Mol Biol 2013; 48:153-72. [PMID: 23339542 DOI: 10.3109/10409238.2012.758084] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In the mammalian testis, extensive restructuring takes place across the seminiferous epithelium at the Sertoli-Sertoli and Sertoli-germ cell interface during the epithelial cycle of spermatogenesis, which is important to facilitate changes in the cell shape and morphology of developing germ cells. However, precise communications also take place at the cell junctions to coordinate the discrete events pertinent to spermatogenesis, namely spermatogonial renewal via mitosis, cell cycle progression and meiosis, spermiogenesis and spermiation. It is obvious that these cellular events are intimately related to the underlying actin-based cytoskeleton which is being used by different cell junctions for their attachment. However, little is known on the biology and regulation of this cytoskeleton, in particular its possible involvement in endocytic vesicle-mediated trafficking during spermatogenesis, which in turn affects cell adhesive function and communication at the cell-cell interface. Studies in other epithelia in recent years have shed insightful information on the intimate involvement of actin dynamics and protein trafficking in regulating cell adhesion and communications. The goal of this critical review is to provide an updated assessment of the latest findings in the field on how these complex processes are being regulated during spermatogenesis. We also provide a working model based on the latest findings in the field including our laboratory to provide our thoughts on an apparent complicated subject, which also serves as the framework for investigators in the field. It is obvious that this model will be rapidly updated when more data are available in future years.
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Affiliation(s)
- Wenhui Su
- The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, New York, NY 10065, USA
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66
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Mok KW, Mruk DD, Lee WM, Cheng CY. Rictor/mTORC2 regulates blood-testis barrier dynamics via its effects on gap junction communications and actin filament network. FASEB J 2013; 27:1137-52. [PMID: 23288930 DOI: 10.1096/fj.12-212977] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
In the mammalian testis, coexisting tight junctions (TJs), basal ectoplasmic specializations, and gap junctions (GJs), together with desmosomes near the basement membrane, constitute the blood-testis barrier (BTB). The most notable feature of the BTB, however, is the extensive network of actin filament bundles, which makes it one of the tightest blood-tissue barriers. The BTB undergoes restructuring to facilitate the transit of preleptotene spermatocytes at stage VIII-IX of the epithelial cycle. Thus, the F-actin network at the BTB undergoes cyclic reorganization via a yet-to-be explored mechanism. Rictor, the key component of mTORC2 that is known to regulate actin cytoskeleton, was shown to express stage-specifically at the BTB in the seminiferous epithelium. Its expression was down-regulated at the BTB in stage VIII-IX tubules, coinciding with BTB restructuring at these stages. Using an in vivo model, a down-regulation of rictor at the BTB was also detected during adjudin-induced BTB disruption, illustrating rictor expression is positively correlated with the status of the BTB integrity. Indeed, the knockdown of rictor by RNAi was found to perturb the Sertoli cell TJ-barrier function in vitro and the BTB integrity in vivo. This loss of barrier function was accompanied by changes in F-actin organization at the Sertoli cell BTB in vitro and in vivo, associated with a loss of interaction between actin and α-catenin or ZO-1. Rictor knockdown by RNAi was also found to impede Sertoli cell-cell GJ communication, disrupting protein distribution (e.g., occludin, ZO-1) at the BTB, illustrating that rictor is a crucial BTB regulator.
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Affiliation(s)
- Ka-Wai Mok
- Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, 1230 York Ave, New York, NY 10065, USA
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