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Asian Journal of Andrology 2021Male meiosis is a complex process whereby spermatocytes undergo cell division to form haploid cells. This review focuses on the role of retinoic acid (RA) in meiosis, as... (Review)
Review
Male meiosis is a complex process whereby spermatocytes undergo cell division to form haploid cells. This review focuses on the role of retinoic acid (RA) in meiosis, as well as several processes regulated by RA before cell entry into meiosis that are critical for proper meiotic entry and completion. Here, we discuss RA metabolism in the testis as well as the roles of stimulated by retinoic acid gene 8 (STRA8) and MEIOSIN, which are responsive to RA and are critical for meiosis. We assert that transcriptional regulation in the spermatogonia is critical for successful meiosis.
Topics: Animals; Cell Differentiation; Humans; Meiosis; Spermatogenesis; Tretinoin
PubMed: 34472453
DOI: 10.4103/aja202156 -
Reproductive Biology Mar 2022D-Aspartate (D-Asp) and its methylated form N-methyl-d-aspartate (NMDA) promote spermatogenesis by stimulating the biosynthesis of sex steroid hormones. d-Asp also...
D-Aspartate (D-Asp) and its methylated form N-methyl-d-aspartate (NMDA) promote spermatogenesis by stimulating the biosynthesis of sex steroid hormones. d-Asp also induces spermatogonia proliferation directly by activating the ERK/Aurora B pathway. In the present study, a mouse spermatocyte-derived cell line (GC-2) which represents a stage between preleptotene spermatocyte and round spermatids was exposed to 200 μM d-Asp or 50 μM NMDA for 30 min, 2 h, and 4 h to explore the influence of these amino acids on cell proliferation and mitochondrial activities occurring during this process. By Western blotting analyses, the expressions of AMPAR (GluA1-GluA2/3 subunits), cell proliferation as well as mitochondria functionality markers were determined at different incubation times. The results revealed that d-Asp or NMDA stimulate proliferation and meiosis in the GC-2 cells via the AMPAR/ERK/Akt pathway, which led to increased levels of the PCNA, p-H3, and SYCP3 proteins. The effects of d-Asp and NMDA on the mitochondrial functionality of the GC-2 cells strongly suggested an active role of these amino acids in germ cell maturation. In both d-Asp- and NMDA-treated GC-2 cells mitochondrial biogenesis as well as mitochondrial fusion are increased while mitochondria fission is inhibited. Finally, the findings showed that NMDA significantly increased the expressions of the CII, CIII, CIV, and CV complexes of oxidative phosphorylation system (OXPHOS), whereas d-Asp induced a significant increase in the expressions only of the CIV and CV complexes. The present study provides novel insights into the mechanisms underlying the role of d-Asp and NMDA in promoting spermatogenesis.
Topics: Animals; D-Aspartic Acid; Male; Mice; N-Methylaspartate; Spermatocytes; Spermatogenesis; Spermatogonia
PubMed: 35032869
DOI: 10.1016/j.repbio.2021.100601 -
BioRxiv : the Preprint Server For... Dec 2023Spermatogenesis is a unidirectional differentiation process that generates haploid sperm, but how the gene expression program that directs this process is established is...
Spermatogenesis is a unidirectional differentiation process that generates haploid sperm, but how the gene expression program that directs this process is established is largely unknown. Here we determine the high-resolution 3D chromatin architecture of male germ cells during spermatogenesis and show that CTCF-mediated 3D chromatin predetermines the gene expression program required for spermatogenesis. In undifferentiated spermatogonia, CTCF-mediated chromatin contacts on autosomes pre-establish meiosis-specific super-enhancers (SE). These meiotic SE recruit the master transcription factor A-MYB in meiotic spermatocytes, which strengthens their 3D contacts and instructs a burst of meiotic gene expression. We also find that at the mitosis-to-meiosis transition, the germline-specific Polycomb protein SCML2 resolves chromatin loops that are specific to mitotic spermatogonia. Moreover, SCML2 and A-MYB establish the unique 3D chromatin organization of sex chromosomes during meiotic sex chromosome inactivation. We propose that CTCF-mediated 3D chromatin organization enforces epigenetic priming that directs unidirectional differentiation, thereby determining the cellular identity of the male germline.
PubMed: 38076840
DOI: 10.1101/2023.11.30.569508 -
Reproduction (Cambridge, England) Mar 2020Recent studies have shown that the testis is producing several biologically active peptides, namely the F5- and the NC1-peptides from laminin-γ3 and collagen α3 (IV)... (Review)
Review
Recent studies have shown that the testis is producing several biologically active peptides, namely the F5- and the NC1-peptides from laminin-γ3 and collagen α3 (IV) chain, respectively, that promotes blood-testis barrier (BTB) remodeling and also elongated spermatid release at spermiation. Also the LG3/4/5 peptide from laminin-α2 chain promotes BTB integrity which is likely being used for the assembly of a 'new' BTB behind preleptotene spermatocytes under transport at the immunological barrier. These findings thus provide a new opportunity for investigators to better understand the biology of spermatogenesis. Herein, we briefly summarize the recent findings and provide a critical update. We also present a hypothetical model which could serve as the framework for studies in the years to come.
Topics: Adherens Junctions; Animals; Blood-Testis Barrier; Collagen Type IV; Humans; Laminin; Male; Spermatogenesis; Testis
PubMed: 31581125
DOI: 10.1530/REP-19-0288 -
Biology of Reproduction Sep 2021Emerging evidence suggests that exposures in prepuberty, particularly in fathers-to-be, may impact the phenotype of future offspring. Analyses of the RHINESSA cohort... (Review)
Review
Emerging evidence suggests that exposures in prepuberty, particularly in fathers-to-be, may impact the phenotype of future offspring. Analyses of the RHINESSA cohort find that offspring of father's exposed to tobacco smoking or overweight that started in prepuberty demonstrate poorer respiratory health in terms of more asthma and lower lung function. A role of prepuberty onset smoking for offspring fat mass is suggested in the RHINESSA and ALSPAC cohorts, and historic studies suggest that ancestral nutrition during prepuberty plays a role for grand-offspring's health and morbidity. Support for causal relationships between ancestral exposures and (grand-)offspring's health in humans has been enhanced by advancements in statistical analyses that optimize the gain while accounting for the many complexities and deficiencies in human multigeneration data. The biological mechanisms underlying such observations have been explored in experimental models. A role of sperm small RNA in the transmission of paternal exposures to offspring phenotypes has been established, and chemical exposures and overweight have been shown to influence epigenetic programming in germ cells. For example, exposure of adolescent male mice to smoking led to differences in offspring weight and alterations in small RNAs in the spermatozoa of the exposed fathers. It is plausible that male prepuberty may be a time window of particular susceptibility, given the extensive epigenetic reprogramming taking place in the spermatocyte precursors at this age. In conclusion, epidemiological studies in humans, mechanistic research, and biological plausibility, all support the notion that exposures in the prepuberty of males may influence the phenotype of future offspring.
Topics: Animals; Child Health; Cohort Studies; Epigenesis, Genetic; Humans; Male; Mice; Paternal Exposure; Puberty; Risk Factors; Smoking; Spermatozoa
PubMed: 34416759
DOI: 10.1093/biolre/ioab158 -
Nucleic Acids Research Apr 2023DNA double-strand breaks (DSBs) are functionally linked to genomic instability in spermatocytes and to male infertility. The heavy metal cadmium (Cd) is known to induce...
DNA double-strand breaks (DSBs) are functionally linked to genomic instability in spermatocytes and to male infertility. The heavy metal cadmium (Cd) is known to induce DNA damage in spermatocytes by unknown mechanisms. Here, we showed that Cd ions impaired the canonical non-homologous end-joining (NHEJ) repair pathway, but not the homologous recombination (HR) repair pathway, through stimulation of Ser2056 and Thr2609 phosphorylation of DNA-PKcs at DSB sites. Hyper-phosphorylation of DNA-PKcs led to its premature dissociation from DNA ends and the Ku complex, preventing recruitment of processing enzymes and further ligation of DNA ends. Specifically, this cascade was initiated by the loss of PP5 phosphatase activity, which results from the dissociation of PP5 from its activating ions (Mn), that is antagonized by Cd ions through a competitive mechanism. In accordance, in a mouse model Cd-induced genomic instability and consequential male reproductive dysfunction were effectively reversed by a high dosage of Mn ions. Together, our findings corroborate a protein phosphorylation-mediated genomic instability pathway in spermatocytes that is triggered by exchange of heavy metal ions.
Topics: Animals; Humans; Male; Mice; Cadmium; DNA; DNA End-Joining Repair; DNA Repair; Genomic Instability; Infertility, Male; Ions; Phosphorylation; Recombinational DNA Repair; Spermatocytes
PubMed: 36869674
DOI: 10.1093/nar/gkad128 -
MicroRNA-202 safeguards meiotic progression by preventing premature SEPARASE-mediated REC8 cleavage.EMBO Reports Aug 2022MicroRNAs (miRNAs) are believed to play important roles in mammalian spermatogenesis but the in vivo functions of single miRNAs in this highly complex developmental...
MicroRNAs (miRNAs) are believed to play important roles in mammalian spermatogenesis but the in vivo functions of single miRNAs in this highly complex developmental process remain unclear. Here, we report that miR-202, a member of the let-7 family, plays an important role in spermatogenesis by phenotypic evaluation of miR-202 knockout (KO) mice. Loss of miR-202 results in spermatocyte apoptosis and perturbation of the zygonema-to-pachynema transition. Multiple processes during meiosis prophase I including synapsis and crossover formation are disrupted, and inter-sister chromatid synapses are detected. Moreover, we demonstrate that Separase mRNA is a miR-202 direct target and provides evidence that miR-202 upregulates REC8 by repressing Separase expression. Therefore, we have identified miR-202 as a new regulating noncoding gene that acts on the established SEPARASE-REC8 axis in meiosis.
Topics: Animals; Cell Cycle Proteins; Chromatids; Male; Meiosis; Mice; MicroRNAs; Separase
PubMed: 35712867
DOI: 10.15252/embr.202154298 -
Animals : An Open Access Journal From... May 2024We identified Wdr17 as a highly expressed gene in pachytene spermatocytes by transcriptomic analysis of mouse testis. Germ cell-deficient infertile mouse models had...
We identified Wdr17 as a highly expressed gene in pachytene spermatocytes by transcriptomic analysis of mouse testis. Germ cell-deficient infertile mouse models had significantly reduced Wdr17 expression. We performed gene interference and overexpression in the mouse spermatocyte cell line GC-2spd(ts) and investigated how Wdr17 affects spermatocyte growth and development. Our results showed that Wdr17 suppression significantly decreased cell growth rate and increased cell apoptosis in GC-2spd(ts) cells. Wdr17 suppression also arrested the cell cycle at the G1 phase. On the contrary, Wdr17 overexpression significantly promoted cell proliferation and inhibited cell apoptosis in GC-2spd(ts) cells. More cells were enriched at the S stage with a concomitant reduction of cells at the G1 stage. Wdr17 promotes mouse spermatocyte proliferation by advancing cell cycle progression and inhibiting cell apoptosis, indicating its potential role in regulating spermatogenesis in the mouse.
PubMed: 38791636
DOI: 10.3390/ani14101418 -
Andrology May 2023Germ granules are large cytoplasmic ribonucleoprotein complexes that emerge in the germline to participate in RNA regulation. The two most prominent germ granules are...
BACKGROUND
Germ granules are large cytoplasmic ribonucleoprotein complexes that emerge in the germline to participate in RNA regulation. The two most prominent germ granules are the intermitochondrial cement (IMC) in meiotic spermatocytes and the chromatoid body (CB) in haploid round spermatids, both functionally linked to the PIWI-interacting RNA (piRNA) pathway.
AIMS
In this study, we clarified the IMC function by identifying proteins that form complexes with a well-known IMC protein PIWIL2/MILI in the mouse testis.
RESULTS
The PIWIL2 interactome included several proteins with known functions in piRNA biogenesis. We further characterized the expression and localization of two of the identified proteins, Exonuclease 3'-5' domain-containing proteins EXD1 and EXD2, and confirmed their localization to the IMC. We showed that EXD2 interacts with PIWIL2, and that the mutation of Exd2 exonuclease domain in mice induces misregulation of piRNA levels originating from specific pachytene piRNA clusters, but does not disrupt male fertility.
CONCLUSION
Altogether, this study highlights the central role of the IMC as a platform for piRNA biogenesis, and suggests that EXD1 and EXD2 function in the IMC-mediated RNA regulation in postnatal male germ cells.
Topics: Mice; Male; Animals; Spermatocytes; Piwi-Interacting RNA; Spermatogenesis; Germ Cell Ribonucleoprotein Granules; Exonucleases; Proteins; RNA; RNA, Small Interfering; Testis
PubMed: 36624638
DOI: 10.1111/andr.13361 -
Reproductive Biology Jun 2023Spermatocyte apoptosis is the primary cause of a poor outcome after hypoxia-triggered spermatogenesis reduction (HSR). Vacuolar H-ATPase (V-ATPase) is involved in the...
https://elsevier.proofcentral.com/en-us/landing-page.html?token=baf280639f2773e07701834b1c13daInhibition of spermatogenesis by hypoxia is mediated by V-ATPase via the JNK/c-Jun pathway in mice.
Spermatocyte apoptosis is the primary cause of a poor outcome after hypoxia-triggered spermatogenesis reduction (HSR). Vacuolar H-ATPase (V-ATPase) is involved in the regulation of hypoxia-induced spermatocyte apoptosis; however, the underlying mechanism remains to be elucidated. The aim of this study was to investigate the effect of V-ATPase deficiency on spermatocyte apoptosis and the relationship between c-Jun and apoptosis in primary spermatocytes induced by hypoxia. We found that mice under hypoxia exposure for 30 days demonstrated a marked spermatogenesis reduction and downregulation of V-ATPase expression, which were assessed by a TUNEL assay and western blotting, respectively. V-ATPase deficiency resulted in more severe spermatogenesis reduction and spermatocyte apoptosis after hypoxia exposure. We also observed that silencing V-ATPase expression enhanced JNK/c-Jun activation and death receptor-mediated apoptosis in primary spermatocytes. However, inhibition of c-Jun attenuated V-ATPase deficiency-induced spermatocyte apoptosis in primary spermatocytes. In conclusion, the data in this study suggest that V-ATPase deficiency aggravated hypoxia-induced spermatogenesis reduction by promoting spermatocyte apoptosis in mice via the JNK/c-Jun pathway.
Topics: Male; Mice; Animals; Signal Transduction; Adenosine Triphosphatases; Spermatogenesis; MAP Kinase Signaling System; Apoptosis; Hypoxia
PubMed: 37023662
DOI: 10.1016/j.repbio.2023.100761