scholarly journals Regulation of spermiogenesis, spermiation and blood–testis barrier dynamics: novel insights from studies on Eps8 and Arp3

2011 ◽  
Vol 435 (3) ◽  
pp. 553-562 ◽  
Author(s):  
C. Yan Cheng ◽  
Dolores D. Mruk
Keyword(s):  
Sertoli Cell ◽  
Morphological Changes ◽  
Growth Factor Receptor ◽  
Adhesion Protein ◽  
Apical Compartment ◽  
Epidermal Growth ◽  
Actin Regulatory Proteins ◽  
Filament Network ◽  
Ectoplasmic Specialization ◽  
Blood Testis Barrier

Spermiogenesis in the mammalian testis is the most critical post-meiotic developmental event occurring during spermatogenesis in which haploid spermatids undergo extensive cellular, molecular and morphological changes to form spermatozoa. Spermatozoa are then released from the seminiferous epithelium at spermiation. At the same time, the BTB (blood–testis barrier) undergoes restructuring to facilitate the transit of preleptotene spermatocytes from the basal to the apical compartment. Thus meiotic divisions take place behind the BTB in the apical compartment to form spermatids. These germ cells enter spermiogenesis to transform into elongating spermatids and then into spermatozoa to replace those that were released in the previous cycle. However, the mole-cular regulators that control spermiogenesis, in particular the dynamic changes that occur at the Sertoli cell–spermatid interface and at the BTB, are not entirely known. This is largely due to the lack of suitable animal models which can be used to study these events. During the course of our investigation to develop adjudin [1-(2,4-dichlorobenzyl)-1H-indazole-3-carbohydrazide] as a potential male contraceptive, this drug was shown to ‘accelerate’ spermiation by inducing the release of premature spermatids from the epithelium. Using this model, we have identified several molecules that are crucial in regulating the actin filament network and the unique adhesion protein complex at the Sertoli cell–spermatid interface known as the apical ES (ectoplasmic specialization). In the present review, we critically evaluate these and other findings in the literature as they relate to the restricted temporal and spatial expression of two actin regulatory proteins, namely Eps8 (epidermal growth factor receptor pathway substrate 8) and Arp3 (actin-related protein 3), which regulate these events.

scholarly journals Drug transporters and blood–testis barrier function

2011 ◽  
Vol 209 (3) ◽  
pp. 337-351 ◽  
Author(s):  
Linlin Su ◽  
Dolores D Mruk ◽  
Will M Lee ◽  
C Yan Cheng
Keyword(s):  
Sertoli Cell ◽  
Barrier Function ◽  
Drug Transporters ◽  
Organic Anion ◽  
Permeability Barrier ◽  
Host Immune System ◽  
Slc Transporters ◽  
Apical Compartment ◽  
Immunological Barrier ◽  
Blood Testis Barrier

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 post-meiotic 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 [3H]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.

scholarly journals c-Yes regulates cell adhesion at the apical ectoplasmic specialization-blood-testis barrier axis via its effects on protein recruitment and distribution

2013 ◽  
Vol 304 (2) ◽  
pp. E145-E159 ◽  
Author(s):  
Xiang Xiao ◽  
Dolores D. Mruk ◽  
C. Yan Cheng
Keyword(s):  
Cell Adhesion ◽  
Sertoli Cell ◽  
Germ Cells ◽  
Early Stage ◽  
Seminiferous Epithelium ◽  
Permeability Barrier ◽  
Cell Interface ◽  
Ectoplasmic Specialization ◽  
Cell Cell ◽  
Blood Testis Barrier

During spermatogenesis, extensive restructuring takes place at the cell-cell interface since developing germ cells migrate progressively from the basal to the adluminal compartment of the seminiferous epithelium. Since germ cells per se are not motile cells, their movement relies almost exclusively on the Sertoli cell. Nonetheless, extensive exchanges in signaling take place between these cells in the seminiferous epithelium. c-Yes, a nonreceptor protein tyrosine kinase belonging to the Src family kinases (SFKs) and a crucial signaling protein, was recently shown to be upregulated at the Sertoli cell-cell interface at the blood-testis barrier (BTB) at stages VIII–IX of the seminiferous epithelial cycle of spermatogenesis. It was also highly expressed at the Sertoli cell-spermatid interface known as apical ectoplasmic specialization (apical ES) at stage V to early stage VIII of the epithelial cycle during spermiogenesis. Herein, it was shown that the knockdown of c-Yes by RNAi in vitro and in vivo affected both Sertoli cell adhesion at the BTB and spermatid adhesion at the apical ES, causing a disruption of the Sertoli cell tight junction-permeability barrier function, germ cell loss from the seminiferous epithelium, and also a loss of spermatid polarity. These effects were shown to be mediated by changes in distribution and/or localization of adhesion proteins at the BTB (e.g., occludin, N-cadherin) and at the apical ES (e.g., nectin-3) and possibly the result of changes in the underlying actin filaments at the BTB and the apical ES. These findings implicate that c-Yes is a likely target of male contraceptive research.

scholarly journals EGFR/ErbB Inhibition Promotes OPC Maturation up to Axon Engagement by Co-Regulating PIP2 and MBP

Cells ◽  
2019 ◽  
Vol 8 (8) ◽  
pp. 844 ◽  
Author(s):  
Emanuela Nocita ◽  
Alice Del Giovane ◽  
Marta Tiberi ◽  
Laura Boccuni ◽  
Denise Fiorelli ◽  
...  
Keyword(s):  
Gene Silencing ◽  
Morphological Changes ◽  
Growth Factor Receptor ◽  
Study Drug ◽  
Drug Efficacy ◽  
Adult Brain ◽  
Egfr Inhibition ◽  
Epidermal Growth ◽  
Oligodendrocyte Precursor ◽  
Neuronal Precursor Cell

Remyelination in the adult brain relies on the reactivation of the Neuronal Precursor Cell (NPC) niche and differentiation into Oligodendrocyte Precursor Cells (OPCs) as well as on OPC maturation into myelinating oligodendrocytes (OLs). These two distinct phases in OL development are defined by transcriptional and morphological changes. How this differentiation program is controlled remains unclear. We used two drugs that stimulate myelin basic protein (MBP) expression (Clobetasol and Gefitinib) alone or combined with epidermal growth factor receptor (EGFR) or Retinoid X Receptor gamma (RXRγ) gene silencing to decode the receptor signaling required for OPC differentiation in myelinating OLs. Electrospun polystyrene (PS) microfibers were used as synthetic axons to study drug efficacy on fiber engagement. We show that EGFR inhibition per se stimulates MBP expression and increases Clobetasol efficacy in OPC differentiation. Consistent with this, Clobetasol and Gefitinib co-treatment, by co-regulating RXRγ, MBP and phosphatidylinositol 4,5-bisphosphate (PIP2) levels, maximizes synthetic axon engagement. Conversely, RXRγ gene silencing reduces the ability of the drugs to promote MBP expression. This work provides a view of how EGFR/ErbB inhibition controls OPC differentiation and indicates the combination of Clobetasol and Gefitinib as a potent remyelination-enhancing treatment.

Regulation of epidermal growth factor receptor expression and morphology of lung epithelial cells by interleukin-1β

2020 ◽  
Vol 168 (2) ◽  
pp. 113-123
Author(s):  
Izumi Nakayama ◽  
Sayomi Higa-Nakamine ◽  
Ayako Uehara ◽  
Kazuhiro Sugahara ◽  
Manabu Kakinohana ◽  
...  
Keyword(s):  
Epidermal Growth Factor Receptor ◽  
Growth Factor ◽  
Epithelial Cells ◽  
Map Kinase ◽  
Morphological Changes ◽  
A549 Cells ◽  
Growth Factor Receptor ◽  
Alveolar Epithelial Cells ◽  
Alveolar Epithelial ◽  
Epidermal Growth

Abstract Accumulating evidences suggested that the overactivation of epidermal growth factor receptor (EGFR) was involved in the development of adult respiratory distress syndrome and pulmonary fibrosis. Elucidation of the mechanisms that regulate EGFR residence on the plasma membrane during inflammatory lung conditions is important for identifying potential therapies. We have demonstrated that flagellin phosphorylated EGFR at Ser1047 and induced transient EGFR internalization. In this study, we examined the molecular pathway and effect of interleukin 1 beta (IL-1β) on EGFR in alveolar epithelial cells. Treatment of A549 cells with IL-1β induced the activation of p38 mitogen-activated protein kinase (MAP kinase) and MAP kinase-activated protein kinase-2 (MAPKAPK-2), as well as EGFR phosphorylation at serine 1047. Both MAPKAPK-2 activation and EGFR phosphorylation were inhibited by SB203580, a p38 MAP kinase inhibitor. In addition, MK2a inhibitor (a MAPKAPK-2 inhibitor) suppressed EGFR phosphorylation. Assessment of the biotinylation of cell surface proteins indicated that IL-1β induced EGFR internalization. Furthermore, long-term treatment of A549 cells with IL-1β caused morphological changes and loss of cell–cell contact. Moreover, IL-1β augmented the effect of transforming growth factor beta 1 on the epithelial–mesenchymal transition. These results suggested that IL-1β regulates EGFR functions and induces morphological changes of alveolar epithelial cells.

scholarly journals An Occludin-Focal Adhesion Kinase Protein Complex at the Blood-Testis Barrier: A Study Using the Cadmium Model

Endocrinology ◽  
2009 ◽  
Vol 150 (7) ◽  
pp. 3336-3344 ◽  
Author(s):  
Erica R. Siu ◽  
Elissa W. P. Wong ◽  
Dolores D. Mruk ◽  
K. L. Sze ◽  
Catarina S. Porto ◽  
...  
Keyword(s):  
Focal Adhesion Kinase ◽  
Sertoli Cell ◽  
Focal Adhesion ◽  
Adhesion Molecule ◽  
Protein Complex ◽  
Permeability Barrier ◽  
Ectoplasmic Specialization ◽  
Blood Testis Barrier

Several integral membrane proteins that constitute the blood-testis barrier (BTB) in mammalian testes, in particular rodents, are known to date. These include tight junction (TJ) proteins (e.g. occludin, junctional adhesion molecule-A, claudins), basal ectoplasmic specialization proteins (e.g. N-cadherin), and gap junction proteins (e.g. connexin43). However, the regulators (e.g. protein kinases and phosphatases) that affect these proteins, such as their interaction with the cytoskeletal actin, which in turn confer cell adhesion at the TJ, remain largely unknown. We report herein that focal adhesion kinase (FAK) is a putative interacting partner of occludin, but not claudin-11 or junctional adhesion molecule-A. Immunohistochemistry and fluorescence microscopy studies illustrated that the expression of FAK in the seminiferous epithelium of adult rat testes was stage specific. FAK colocalized with occludin at the BTB in virtually all stages of the seminiferous epithelial cycle but considerably diminished in stages VIII–IX, at the time of BTB restructuring to facilitate the transit of primary leptotene spermatocytes. Using Sertoli cells cultured in vitro with established TJ-permeability barrier and ultrastructures of TJ, basal ectoplasmic specialization and desmosome-like junction that mimicked the BTB in vivo, FAK was shown to colocalize with occludin and zonula occludens-1 (ZO-1) at the Sertoli-Sertoli cell interface. When these Sertoli cell cultures were treated with CdCl2 to perturb the TJ-barrier function, occludin underwent endocytic-mediated internalization in parallel with FAK and ZO-1. Thus, these findings demonstrate that FAK is an integrated regulatory component of the occludin-ZO-1 protein complex, suggesting that functional studies can be performed to study the role of FAK in BTB dynamics.

scholarly journals Filamin A Is a Regulator of Blood-Testis Barrier Assembly during Postnatal Development in the Rat Testis

Endocrinology ◽  
2012 ◽  
Vol 153 (10) ◽  
pp. 5023-5035 ◽  
Author(s):  
Wenhui Su ◽  
Dolores D. Mruk ◽  
Pearl P. Y. Lie ◽  
Wing-yee Lui ◽  
C. Yan Cheng
Keyword(s):  
Postnatal Development ◽  
Sertoli Cell ◽  
Actin Filament ◽  
Permeability Barrier ◽  
Filamin A ◽  
Rat Testis ◽  
Filament Network ◽  
Blood Testis Barrier

Abstract The blood-testis barrier (BTB) is an important ultrastructure in the testis. A delay in its assembly during postnatal development leads to meiotic arrest. Also, a disruption of the BTB by toxicants in adult rats leads to a failure in spermatogonial differentiation. However, the regulation of BTB assembly remains unknown. Herein, filamin A, an actin filament cross-linker that is known to maintain and regulate cytoskeleton structure and function in other epithelia, was shown to be highly expressed during the assembly of Sertoli cell BTB in vitro and postnatal development of BTB in vivo, perhaps being used to maintain the actin filament network at the BTB. A knockdown of filamin A by RNA interference was found to partially perturb the Sertoli cell tight junction (TJ) permeability barrier both in vitro and in vivo. Interestingly, this down-regulating effect on the TJ barrier function after the knockdown of filamin A was associated with a mis-localization of both TJ and basal ectoplasmic specialization proteins. Filamin A knockdown also induced a disorganization of the actin filament network in Sertoli cells in vitro and in vivo. Collectively, these findings illustrate that filamin A regulates BTB assembly by recruiting these proteins to the microenvironment in the seminiferous epithelium to serve as the building blocks. In short, filamin A participates in BTB assembly by regulating protein recruitment during postnatal development in the rat testis.

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