scholarly journals Regulation of BTB Dynamics in Spermatogenesis—Insights From the Adjudin Model

2019 ◽  
Vol 172 (1) ◽  
pp. 75-88 ◽  
Author(s):  
Bai-Ping Mao ◽  
Linxi Li ◽  
Ming Yan ◽  
Renshan Ge ◽  
Qingquan Lian ◽  
...  
Keyword(s):  
Germ Cell ◽  
Low Dose ◽  
Mammalian Target Of Rapamycin ◽  
Underlying Mechanism ◽  
Seminiferous Epithelium ◽  
Regulatory Proteins ◽  
Cell Organelles ◽  
Adult Rats ◽  
Downstream Signaling ◽  
Cellular Events

Abstract During spermatogenesis, cell organelles, and germ cells, most notably haploid spermatids, are transported across the seminiferous epithelium so that fully developed spermatids line-up at the edge of the tubule lumen to undergo spermiation at stage VIII of the cycle. Studies have suggested that the microtubule (MT)-based cytoskeleton is necessary to support these cellular events. However, the regulatory molecule(s) and underlying mechanism(s) remain poorly understood. Herein, we sought to better understand this event by using an adjudin-based animal model. Adult rats were treated with adjudin at low-dose (10 mg/kg b.w.) which by itself had no notable effects on spermatogenesis. Rats were also treated with low-dose adjudin combined with overexpression of 2 endogenously produced blood-testis barrier (BTB) modifiers, namely rpS6 (ribosomal protein S6, the downstream signaling protein of mammalian target of rapamycin complex 1 [mTORC1]) and F5-peptide (a biological active peptide released from laminin-γ3 chain at the Sertoli-spermatid interface) versus the 2 BTB modifiers alone. Overexpression of these 2 BTB modifiers in the testis was shown to enhance delivery of adjudin to the testis, effectively inducing disruptive changes in MT cytoskeletons, causing truncation of MT conferred tracks that led to their collapse across the epithelium. The net result was massive germ cell exfoliation in the tubules, disrupting germ cell transport and cell adhesion across the seminiferous epithelium that led to aspermatogenesis. These changes were the result of disruptive spatial expression of several MT-based regulatory proteins. In summary, MT cytoskeleton supported by the network of MT regulatory proteins is crucial to maintain spermatogenesis.

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

2018 ◽  
Vol 315 (5) ◽  
pp. E924-E948 ◽  
Author(s):  
Qing Wen ◽  
Elizabeth I. Tang ◽  
Wing-yee Lui ◽  
Will M. Lee ◽  
Chris K. C. Wong ◽  
...  
Keyword(s):  
Germ Cell ◽  
Heavy Chain ◽  
Sertoli Cells ◽  
Cytoplasmic Dynein ◽  
Seminiferous Epithelium ◽  
Organelle Transport ◽  
Cellular Events

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. Both treatments were shown to extensively induce disruption of MT organization across Sertoli cells in vitro and the testis in vivo. These changes also perturbed the transport of spermatids and other organelles (such as phagosomes) across the epithelium. These changes thus led to disruption of spermatogenesis. Interestingly, the knockdown of dynein 1 or its inactivation by ciliobrevin D also perturbed gross disruption of F-actin across the Sertoli cells in vitro and the seminiferous epithelium in vivo, illustrating there are cross talks between the two cytoskeletons in the testis. In summary, these findings confirm the role of cytoplasmic dynein 1 to support the transport of spermatids and organelles across the seminiferous epithelium during the epithelial cycle of spermatogenesis.

scholarly journals F5-Peptide and mTORC1/rpS6 Effectively Enhance BTB Transport Function in the Testis—Lesson From the Adjudin Model

Endocrinology ◽  
2019 ◽  
Vol 160 (8) ◽  
pp. 1832-1853 ◽  
Author(s):  
Baiping Mao ◽  
Linxi Li ◽  
Ming Yan ◽  
Chris K C Wong ◽  
Bruno Silvestrini ◽  
...  
Keyword(s):  
Mammalian Target Of Rapamycin ◽  
Regulatory Proteins ◽  
Permeability Barrier ◽  
Oral Gavage ◽  
Downstream Signaling ◽  
Ribosomal Protein S6 ◽  
Mtorc1 Signaling ◽  
Tight Junction Permeability ◽  
Stage Viii ◽  
Immunological Barrier

Abstract During spermatogenesis, the blood–testis barrier (BTB) undergoes cyclic remodeling that is crucial to support the transport of preleptotene spermatocytes across the immunological barrier at stage VIII to IX of the epithelial cycle. Studies have shown that this timely remodeling of the BTB is supported by several endogenously produced barrier modifiers across the seminiferous epithelium, which include the F5-peptide and the ribosomal protein S6 [rpS6; a downstream signaling molecule of the mammalian target of rapamycin complex 1 (mTORC1)] signaling protein. Herein, F5-peptide and a quadruple phosphomimetic (and constitutively active) mutant of rpS6 [i.e., phosphorylated (p-)rpS6-MT] that are capable of inducing reversible immunological barrier remodeling, by making the barrier “leaky” transiently, were used for their overexpression in the testis to induce BTB opening. We sought to examine whether this facilitated the crossing of the nonhormonal male contraceptive adjudin at the BTB when administered by oral gavage, thereby effectively improving its BTB transport to induce germ cell adhesion and aspermatogenesis. Indeed, it was shown that combined overexpression of F5-peptide and p-rpS6-MT and a low dose of adjudin, which by itself had no noticeable effects on spermatogenesis, was capable of perturbing the organization of actin- and microtubule (MT)-based cytoskeletons through changes in the spatial expression of actin- and MT-binding/regulatory proteins to the corresponding cytoskeleton. These findings thus illustrate the possibility of delivering drugs to any target organ behind a blood–tissue barrier by modifying the tight junction permeability barrier using endogenously produced barrier modifiers based on findings from this adjudin animal model.

scholarly journals Nitric Oxide and Cyclic Nucleotides: Their Roles in Junction Dynamics and Spermatogenesis

2008 ◽  
Vol 1 (1) ◽  
pp. 25-32 ◽  
Author(s):  
Nikki P. Y. Lee ◽  
C. Yan Cheng
Keyword(s):  
Nitric Oxide ◽  
Germ Cell ◽  
Tight Junctions ◽  
Germ Cells ◽  
Cell Movement ◽  
Soluble Guanylyl Cyclase ◽  
Seminiferous Epithelium ◽  
Seminiferous Tubules ◽  
Downstream Signaling ◽  
Oxide Synthase

Spermatogenesis is a highly complicated process in which functional spermatozoa (haploid, 1n) are generated from primitive mitotic spermatogonia (diploid, 2n). This process involves the differentiation and transformation of several types of germ cells as spermatocytes and spermatids undergo meiosis and differentiation. Due to its sophistication and complexity, testis possesses intrinsic mechanisms to modulate and regulate different stages of germ cell development under the intimate and indirect cooperation with Sertoli and Leydig cells, respectively. Furthermore, developing germ cells must translocate from the basal to the apical (adluminal) compartment of the seminiferous epithelium. Thus, extensive junction restructuring must occur to assist germ cell movement. Within the seminiferous tubules, three principal types of junctions are found namely anchoring junctions, tight junctions, and gap junctions. Other less studied junctions are desmosome-like junctions and hemidesmosome junctions. With these varieties of junction types, testes are using different regulators to monitor junction turnover. Among the uncountable junction modulators, nitric oxide (NO) is a prominent candidate due to its versatility and extensive downstream network. NO is synthesized by nitric oxide synthase (NOS). Three traditional NOS, specified as endothelial NOS (eNOS), inducible NOS (iNOS), and neuronal NOS (nNOS), and one testis-specific nNOS (TnNOS) are found in the testis. For these, eNOS and iNOS were recently shown to have putative junction regulation properties. More important, these two NOSs likely rely on the downstream soluble guanylyl cyclase/cGMP/protein kinase G signaling pathway to regulate the structural components at the tight junctions and adherens junctions in the testes. Apart from the involvement in junction regulation, NOS/NO also participates in controlling the levels of cytokines and hormones in the testes. On the other hand, NO is playing a unique role in modulating germ cell viability and development, and indirectly acting on some aspects of male infertility and testicular pathological conditions. Thus, NOS/NO bears an irreplaceable role in maintaining the homeostasis of the microenvironment in the seminiferous epithelium via its different downstream signaling pathways.

scholarly journals Prenatal and lactation nicotine exposure affects Sertoli cell and gonadotropin levels in rats

Reproduction ◽  
2016 ◽  
Vol 151 (2) ◽  
pp. 117-133 ◽  
Author(s):  
C C Paccola ◽  
S M Miraglia
Keyword(s):  
Epithelial Cells ◽  
Germ Cell ◽  
Sertoli Cells ◽  
Hormone Secretion ◽  
Seminiferous Epithelium ◽  
Nicotine Exposure ◽  
Adult Rats ◽  
Pregnant Rats ◽  
Tubular Lumen ◽  
Hormonal Analysis

Nicotine is largely consumed in the world as a component of cigarettes. It can cross the placenta and reach the milk of smoking mothers. This drug induces apoptosis, affects sex hormone secretion, and leads to male infertility. To investigate the exposure to nicotine during the whole intrauterine and lactation phases in Sertoli cells, pregnant rats received nicotine (2 mg/kg per day) through osmotic minipumps. Male offsprings (30, 60, and 90 days old) had blood collected for hormonal analysis (FSH and LH) and their testes submitted for histophatological study, analysis of the frequency of the stages of seminiferous epithelium cycle, immunolabeling of apoptotic epithelial cells (TUNEL and Fas/FasL), analysis of the function and structure of Sertoli cells (respectively using transferrin and vimentin immunolabeling), and analysis of Sertoli-germ cell junctional molecule (β-catenin immunolabeling). The exposure to nicotine increased the FSH and LH plasmatic levels in adult rats. Although nicotine had not changed the number of apoptotic cells, neither in Fas nor FasL expression, it provoked an intense sloughing of epithelial cells and also altered the frequency of some stages of the seminiferous epithelium cycle. Transferrin and β-catenin expressions were not changed, but vimentin was significantly reduced in the early stages of the seminiferous cycle of the nicotine-exposed adult rats. Thus, we concluded that nicotine exposure during all gestational and lactation periods affects the structure of Sertoli cells by events causing intense germ cell sloughing observed in the tubular lumen and can compromise the fertility of the offspring.

scholarly journals Ionizing Radiation and Translation Control: A Link to Radiation Hormesis?

2020 ◽  
Vol 21 (18) ◽  
pp. 6650
Author(s):  
Usha Kabilan ◽  
Tyson E. Graber ◽  
Tommy Alain ◽  
Dmitry Klokov
Keyword(s):  
Protein Synthesis ◽  
Ionizing Radiation ◽  
Molecular Mechanisms ◽  
Low Dose ◽  
Mrna Translation ◽  
Cellular Responses ◽  
Translation Control ◽  
Cis Acting ◽  
Radiation Hormesis ◽  
Downstream Signaling

Protein synthesis, or mRNA translation, is one of the most energy-consuming functions in cells. Translation of mRNA into proteins is thus highly regulated by and integrated with upstream and downstream signaling pathways, dependent on various transacting proteins and cis-acting elements within the substrate mRNAs. Under conditions of stress, such as exposure to ionizing radiation, regulatory mechanisms reprogram protein synthesis to translate mRNAs encoding proteins that ensure proper cellular responses. Interestingly, beneficial responses to low-dose radiation exposure, known as radiation hormesis, have been described in several models, but the molecular mechanisms behind this phenomenon are largely unknown. In this review, we explore how differences in cellular responses to high- vs. low-dose ionizing radiation are realized through the modulation of molecular pathways with a particular emphasis on the regulation of mRNA translation control.

scholarly journals Correlation between DNA synthesis in the second, third and fourth generations of spermatogonia and the occurrence of apoptosis in both spermatogonia and spermatocytes

Reproduction ◽  
2003 ◽  
pp. 661-668 ◽  
Author(s):  
J Blanco-Rodriguez ◽  
C Martinez-Garcia ◽  
A Porras
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Dna Synthesis ◽  
Functional Significance ◽  
Tunel Assay ◽  
Seminiferous Epithelium ◽  
Cell Cycle Checkpoints ◽  
Clear Correlation ◽  
Cellular Events ◽  
Dna Strand

In the seminiferous epithelium, both DNA synthesis and apoptosis occur at equivalent stages in various species, with apoptosis taking place mainly at the same stages as DNA replication in the second, third and fourth spermatogonial generations. As preservation of the cellular associations found at these stages may have some functional significance, it is important to determine whether there is a correlation between these cellular events. In this study, pairs of immunoperoxidase-stained adjacent testis sections from rats, mice, rabbits and cats in which either bromodeoxyuridine incorporated into the newly synthesized DNA strand (BrdU labelling) or DNA 3' end labelling of the apoptotic DNA fragments (TUNEL assay) were detected were compared. In addition, both events were analysed in double-labelled sections. These two methods revealed a clear correlation between the occurrence of DNA replication in the second to fourth generations of spermatogonia and most physiological apoptosis taking place in both spermatogonia and spermatocytes in the three different mammalian orders (Rodentia, Lagomorpha and Carnivora). This correlation may result from the synchronization of mitotic spermatogonial and meiotic spermatocyte cell cycle checkpoints operating at these stages.

scholarly journals Prodigiosin-Emerged PI3K/Beclin-1-Independent Pathway Elicits Autophagic Cell Death in Doxorubicin-Sensitive and -Resistant Lung Cancer

2018 ◽  
Vol 7 (10) ◽  
pp. 321 ◽  
Author(s):  
Wei-Jun Chiu ◽  
Shian-Ren Lin ◽  
Yu-Hsin Chen ◽  
May-Jwan Tsai ◽  
Max Leong ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Cell Death ◽  
Mammalian Target Of Rapamycin ◽  
Underlying Mechanism ◽  
Beclin 1 ◽  
Class Iii ◽  
Microtubule Associated Proteins ◽  
Associated Proteins ◽  
Anti Tumor Activity

Prodigiosin (PG) belongs to a family of prodiginines isolated from gram-negative bacteria. It is a water insoluble red pigment and a potent proapoptotic compound. This study elucidates the anti-tumor activity and underlying mechanism of PG in doxorubicin-sensitive (Dox-S) and doxorubicin-resistant (Dox-R) lung cancer cells. The cytotoxicity and cell death characteristics of PG in two cells were measured by MTT assay, cell cycle analysis, and apoptosis/autophagic marker analysis. Then, the potential mechanism of PG-induced cell death was evaluated through the phosphatidylinositol-4,5-bisphosphate 3-kinase-p85/Protein kinase B /mammalian target of rapamycin (PI3K-p85/Akt/mTOR) and Beclin-1/phosphatidylinositol-4,5-bisphosphate 3-kinase-Class III (Beclin-1/PI3K-Class III) signaling. Finally, in vivo efficacy was examined by intratracheal inoculation and treatment. There was similar cytotoxicity with PG in both Dox-S and Dox-R cells, where the half maximal inhibitory concentrations (IC50) were all in 10 μM. Based on a non-significant increase in the sub-G1 phase with an increase of microtubule-associated proteins 1A/1B light chain 3B-phosphatidylethanolamine conjugate (LC3-II), the cell death of both cells was categorized to achieve autophagy. Interestingly, an increase in cleaved-poly ADP ribose polymerase (cleaved-PARP) also showed the existence of an apoptosis-sensitive subpopulation. In both Dox-S and Dox-R cells, PI3K-p85/Akt/mTOR signaling pathways were reduced, which inhibited autophagy initiation. However, Beclin-1/PI3K-Class III downregulation implicated non-canonical autophagy pathways were involved in PG-induced autophagy. At completion of the PG regimen, tumors accumulated in the mice trachea and were attenuated by PG treatment, which indicated the efficacy of PG for both Dox-S and Dox-R lung cancer. All the above results concluded that PG is a potential chemotherapeutic agent for lung cancer regimens regardless of doxorubicin resistance.

The murine seminiferous epithelial cycle is pre-figured in the Sertoli cells of the embryonic testis

Development ◽  
2002 ◽  
Vol 129 (3) ◽  
pp. 635-647 ◽  
Author(s):  
Paula M. Timmons ◽  
Peter W. J. Rigby ◽  
Françoise Poirier
Keyword(s):  
Germ Cell ◽  
Sertoli Cells ◽  
Cell Function ◽  
Seminiferous Epithelium ◽  
Developmental Origins ◽  
Sperm Production ◽  
Functional Heterogeneity ◽  
Adult Testis ◽  
Germ Cell Apoptosis ◽  
Cell Lineages

The seminiferous epithelial cycle and spermatogenic wave are conserved features of vertebrate spermatogenic organisation that reflect the need for the rigorous maintenance of sperm production. Although the cycle and the wave of the adult seminiferous epithelium have been well characterised, particularly in rodent species, their developmental origins are unknown. We show that the Sertoli cells of the pre-pubertal mouse, including those of the germ cell-deficient XXSxra mutant, exhibit coordinated, cyclical patterns of gene expression, presaging the situation in the adult testis, where Sertoli cell function is coupled to the spermatogenic cycle. In the case of the galectin 1 gene (Lgals1), localised differential expression in the Sertoli cells can be traced back to neonatal and embryonic stages, making this the earliest known molecular marker of functional heterogeneity in mammalian testis cords. In addition, the timing of germ cell apoptosis in normal pre-pubertal testes is linked to the temporal cycle of the Sertoli cells. These data show that the cycle and wave of the murine seminiferous epithelium originate at a much earlier stage in development than was previously known, and that their maintenance in the early postnatal cords depends exclusively on the somatic cell lineages.

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