Stimulated by retinoic acid gene 8 (STRA8) interacts with the germ cell specific bHLH factor SOHLH1 and represses c-KIT expression in vitro

Differential Impairment Mechanism of Sperm Production via Induction of miR-34c-Activated Apoptosis and Spermatogenesis Pathway in Diet-Induced Obesity and Resistant Mice and GC-1 Spg Cells

Male reproductive dysfunction is a clinical disease, with a large number of cases being idiopathic. Reproductive disorders have been found in obese (diet-induced obesity and diet-induced obesity-resistant) mice, but the mechanism behind the male reproductive dysfunction between them may be different. The purpose of this study was to explore the possible role and mechanism of miR-34c on sperm production in high-fat-diet-induced obesity-resistant (DIO-R) mice and GC-1 spg cells, which may differ from those in high-fat-diet-induced obesity (DIO) mice. In vivo and in vitro experiments were performed. C57BL/6J mice were fed a high-fat diet for 10 weeks to establish the DIO and DIO-R mouse model. GC-1 spg cells were used to verify the mechanism of miR-34c on sperm production. During in vivo experiments, sperm production damage was found in both DIO and DIO-R male mice. Compared to the control mice, significantly decreased levels of testosterone, LH, activities of acrosome enzyme (ACE), HAse, and activating transcription factor 1 (ATF1) were found in both DIO and DIO-R male mice (p < 0.05). Compared with the control group, the ratio of B-cell lymphoma-2 (Bcl-2)/bcl-2-associated X protein (Bax) in the DIO group was significantly decreased, and the expression level of cleaved caspase-3 was significantly increased (p < 0.05). Compared with the control group, the Bcl-2 protein expression level in the testes of the DIO-R group significantly decreased (p < 0.05). However, the Bax expression level increased. Thus, the Bcl-2/Bax ratio significantly decreased (p < 0.01); however, the factor-related apoptosis (Fas), Fas ligand (FasLG), cleaved caspase-8, caspase-8, cleaved caspase-3, and caspase-3 protein expression levels significantly increased (p < 0.05). Compared with the DIO group, in DIO-R mice, the activities of ACE, ATF1, Bcl-2, and Bcl-2/Bax's spermatogenesis protein expression decreased, while the apoptosis-promoting protein expression significantly increased (p < 0.05). During the in vitro experiment, the late and early apoptotic ratio in the miR-34c over-expression group increased. MiR-34c over-expression enhanced the expression of apoptosis-related proteins Fas/FasLG and Bax/Bcl-2 while inhibiting the expression of ATF1 and the sperm-associated protein in GC-1 spg cells. DIO and DIO-R could harm sperm production. DIO-R could impair sperm production by inducing the miR-34c-activated apoptosis and spermatogenesis pathway, which may be different from that of DIO.

A review on the nexus of autophagy genes from the perspective of polycystic ovary syndrome

Polycystic ovary syndrome or PCOS is an endocrine disorder in women of reproductive age. It is a diversified multi factorial disorder and diagnosis is very complicated because of its overlapping symptoms some of which are irregular menstrual cycle, acne in face, excess level of androgen (AE), insulin resistance, obesity, cardiovascular disease, mood disorder and type 2 diabetes (T2DM). PCOS may be caused by hormonal imbalance, genetic and epigenetic vulnerability, hypothalamic and ovarian troubles. PCOS is essentially hyperandrogenimia with oligo-anovulation. This review explains the abnormal regulation of autophagy related genes and proteins in different cells at various stages which leads to the genesis of PCOS. During nutrient starvation cells face stress condition, which it tries to overcome by activating its macroautophagy mechanism and by degrading the cytoplasmic material. This provides energy to the cell facilitating its survival. Downregulation of autophagy related genes in endometria has been observed in PCOS women. PCOS can be managed by maintaining proper lifestyle and medical treatment. Healthy meals and regular exercise can prevent the excessive weight and also reduce the PCOS complications. Medicines such as metformin, clomiphene, and the oral contraceptive pill can also balance the hormonal level. The imbalance in regulation of autophagy genes has been discussed with correlation to PCOS. The different management strategies for PCOS have also been summarized.

NECL2 regulates blood-testis barrier dynamics in mouse testes

The adhesion protein nectin-like molecule 2 (NECL2) is involved in spermatogenesis and participates in the connections between Sertoli cells and germ cells. Necl2 deficiency leads to infertility in male mice. We found that NECL2 is relatively highly expressed on the cell membranes of preleptotene spermatocytes. It is known that preleptotene spermatocytes pass through the blood-testis barrier (BTB) from the base of the seminiferous tubules to the lumen to complete meiosis. We hypothesized that the NECL2 protein on the surfaces of preleptotene spermatocytes has an effect on the BTB when crossing the barrier. Our results showed that Necl2 deficiency caused the levels of proteins in the BTB to be abnormal, such as those of Claudin 3, claudin 11, and Connexin43. NECL2 interacted and colocalized with adhesion proteins forming the BTB, such as Connexin43, Occludin, and N-cadherin. NECL2 regulated BTB dynamics when preleptotene spermatocytes passed through the barrier, and Necl2 deficiency caused BTB damage. Necl2 deletion significantly affected the testicular transcriptome, especially the expression of spermatogenesis-related genes. These results suggest that before meiosis and spermatid development occur, BTB dynamics regulated by NECL2 are necessary for spermatogenesis.

Identification of bHLH family genes in Agaricus bisporus and transcriptional regulation of arginine catabolism-related genes by AbbHLH1 after harvest

Basic helix-loop-helix (bHLH) transcription factors (TFs) are widely distributed in eukaryotes and play an important role in biological growth and development. The identification and functional analyses of bHLH genes/proteins in edible mushrooms (Agaricus bisporus) have yet to be reported. In the present study, we identified 10 putative bHLH members carrying the conserved bHLH domains. Phylogenetic analyses revealed that the 10 AbbHLHs were the closest to sequences of species belonging to 7 different fungal subgroups, which was supported by loop length, intron patterns, and key amino acid residues. The substantial increase after harvest and continuously elevated expression of AbbHLH1 during the development until the disruption of mushroom velum, and the preferential expression in cap and gill tissues suggest the important function of AbbHLH1 in postharvest development of A. bisporus. The relationship of arginine catabolism-related genes with the early stage of postharvest continuing development also was revealed by expression determination. Subcellular localization showed that AbbHLH1 could be localized in nucleus. Importantly, the electrophoretic mobility shift and dual-luciferase reporter assays showed that AbbHLH1 activated the promoters of AbOAT, AbSPDS, and AbSAMDC and suppressed the expression of AbARG, AbUREA, and AbODC, probably for the modulation of arginine catabolism and thus control of postharvest mushroom development. Taken together, the available data provide valuable functional insight into the role of AbbHLH proteins in postharvest mushrooms.

circRNA-miRNA-mRNA network analysis to explore the pathogenesis of abnormal spermatogenesis due to aberrant m6A methylation

Many studies have shown that circRNAs and miRNAs play important roles in many different life processes. However, the function of circRNAs in spermatogenesis remains unknown. Here, we aimed to explore the mechanisms whereby circRNA-miRNAs-mRNAs regulate abnormal m6A methylation in GC-1spg spermatogonia. We first reduced m6A methylation in GC-1spg whole cells after knocking down the m6A methyltransferase enzyme, METTL3. Then, we performed circRNA- and miRNA-seq on GC-1spg cells with low m6A methylation and identified 48 and 50 differentially expressed circRNAs and miRNAs, respectively. We also predicted the targets of the differentially expressed miRNAs by using Miranda software and further constructed the differentially expressed circRNA-differentially expressed miRNA-mRNA ceRNA network. GO analysis was performed on the differentially expressed circRNAs and miRNA-targeted mRNAs, and an interaction network between the proteins of interest was constructed using Cytoscape. The final GO analysis showed that the target mRNAs were involved in sperm formation. Therefore, a PPI network was subsequently constructed and 2 hub genes (H2afx and Dnmt3a) were identified. In this study, we constructed a ceRNA network and explored the regulatory roles of circRNAs and miRNAs in the pathogenesis of abnormal spermatogenesis caused by low levels of methylated m6A. Also, we identified two pivotal genes that may be key factors in infertility caused by abnormal m6A methylation. This may provide some ideas for the treatment of infertility resulting from abnormal spermatogenesis.

The Beginning of Meiosis in Mammalian Female Germ Cells: A Never-Ending Story of Intrinsic and Extrinsic Factors

Meiosis is the unique division of germ cells resulting in the recombination of the maternal and paternal genomes and the production of haploid gametes. In mammals, it begins during the fetal life in females and during puberty in males. In both cases, entering meiosis requires a timely switch from the mitotic to the meiotic cell cycle and the transition from a potential pluripotent status to meiotic differentiation. Revealing the molecular mechanisms underlying these interrelated processes represents the essence in understanding the beginning of meiosis. Meiosis facilitates diversity across individuals and acts as a fundamental driver of evolution. Major differences between sexes and among species complicate the understanding of how meiosis begins. Basic meiotic research is further hindered by a current lack of meiotic cell lines. This has been recently partly overcome with the use of primordial-germ-cell-like cells (PGCLCs) generated from pluripotent stem cells. Much of what we know about this process depends on data from model organisms, namely, the mouse; in mice, the process, however, appears to differ in many aspects from that in humans. Identifying the mechanisms and molecules controlling germ cells to enter meiosis has represented and still represents a major challenge for reproductive medicine. In fact, the proper execution of meiosis is essential for fertility, for maintaining the integrity of the genome, and for ensuring the normal development of the offspring. The main clinical consequences of meiotic defects are infertility and, probably, increased susceptibility to some types of germ-cell tumors. In the present work, we report and discuss data mainly concerning the beginning of meiosis in mammalian female germ cells, referring to such process in males only when pertinent. After a brief account of this process in mice and humans and an historical chronicle of the major hypotheses and progress in this topic, the most recent results are reviewed and discussed.

Single-cell transcriptomics reveals male germ cells and Sertoli cells developmental patterns in dairy goats

Spermatogenesis holds considerable promise for human-assisted reproduction and livestock breeding based on stem cells. It occurs in seminiferous tubules within the testis, which mainly comprise male germ cells and Sertoli cells. While the developmental progression of male germ cells and Sertoli cells has been widely reported in mice, much less is known in other large animal species, including dairy goats. In this study, we present the data of single cell RNA sequencing (scRNA-seq) for 25,373 cells from 45 (pre-puberty), 90 (puberty), and 180-day-old (post-puberty) dairy goat testes. We aimed to identify genes that are associated with key developmental events in male germ cells and Sertoli cells. We examined the development of spermatogenic cells and seminiferous tubules from 15, 30, 45, 60, 75, 90, 180, and 240-day-old buck goat testes. scRNA-seq clustering analysis of testicular cells from pre-puberty, puberty, and post-puberty goat testes revealed several cell types, including cell populations with characteristics of spermatogonia, early spermatocytes, spermatocytes, spermatids, Sertoli cells, Leydig cells, macrophages, and endothelial cells. We mapped the timeline for male germ cells development from spermatogonia to spermatids and identified gene signatures that define spermatogenic cell populations, such as AMH, SOHLH1, INHA, and ACTA2. Importantly, using immunofluorescence staining for different marker proteins (UCHL1, C-KIT, VASA, SOX9, AMH, and PCNA), we explored the proliferative activity and development of male germ cells and Sertoli cells. Moreover, we identified the expression patterns of potential key genes associated with the niche-related key pathways in male germ cells of dairy goats, including testosterone, retinoic acid, PDGF, FGF, and WNT pathways. In summary, our study systematically investigated the elaborate male germ cells and Sertoli cells developmental patterns in dairy goats that have so far remained largely unknown. This information represents a valuable resource for the establishment of goat male reproductive stem cells lines, induction of germ cell differentiation in vitro, and the exploration of sequential cell fate transition for spermatogenesis and testicular development at single-cell resolution.

Meiosis initiation: a story of two sexes in all creatures great and small

Meiosis facilitates diversity across individuals and serves as a major driver of evolution. However, understanding how meiosis begins is complicated by fundamental differences that exist between sexes and species. Fundamental meiotic research is further hampered by a current lack of human meiotic cells lines. Consequently, much of what we know relies on data from model organisms. However, contextualising findings from yeast, worms, flies and mice can be challenging, due to marked differences in both nomenclature and the relative timing of meiosis. In this review, we set out to combine current knowledge of signalling and transcriptional pathways that control meiosis initiation across the sexes in a variety of organisms. Furthermore, we highlight the emerging links between meiosis initiation and oncogenesis, which might explain the frequent re-expression of normally silent meiotic genes in a variety of human cancers.

Stimulated by retinoic acid gene 8 (STRA8) interacts with the germ cell specific bHLH factor SOHLH1 and represses c-KIT expression in vitro

STRA8 (Stimulated by Retinoic Acid Gene 8) controls the crucial decision of germ cells to engage meiotic division up and down‐regulating genes involved in the meiotic programme. It has been proven as an amplifier of genes involved in cell cycle control and chromosome events, however, how STRA8 functions as negative regulator are not well understood. In this study, we demonstrate that STRA8 can interact with itself and with other basic Helix‐Loop‐Helix (bHLH) transcription factors through its HLH domain and that this domain is important for its ability to negatively interfere with the Ebox‐mediated transcriptional activity of bHLH transcription factors. Significantly, we show that STRA8 interacts with TCF3/E47, a class I bHLH transcription factors, and with SOHLH1, a gonadal‐specific bHLH, in male germ cells obtained from prepuberal mouse testis. We demonstrated that STRA8, indirectly, is able to exert a negative control on the SOHLH1‐dependent stimulation of c‐KIT expression in late differentiating spermatogonia and preleptotene spermatocytes. Although part of this results were obtained only ‘in vitro’, they support the notion that STRA8 interacting with different transcription factors, besides its established role as ‘amplifier’ of meiotic programme, is able to finely modulate the balance between spermatogonia proliferation, differentiation and acquisition of meiotic competence.