Expression of Flotilin-2 and Acrosome Biogenesis Are Regulated by MiR-124 during Spermatogenesis

17α-estradiol does not adversely affect sperm parameters or fertility in male mice: implications for reproduction-longevity trade-offs

17α-estradiol (17α-E2) is referred to as a nonfeminizing estrogen that was recently found to extend healthspan and lifespan in male, but not female, mice. Despite an abundance of data indicating that 17α-E2 attenuates several hallmarks of aging in male rodents, very little is known with regard to its effects on feminization and fertility. In these studies, we evaluated the effects of 17α-E2 on several markers of male reproductive health in two independent cohorts of mice. In alignment with our previous reports, chronic 17α-E2 treatment prevented gains in body mass, but did not adversely affect testes mass or seminiferous tubule morphology. We subsequently determined that chronic 17α-E2 treatment also did not alter plasma 17β-estradiol or estrone concentrations, while mildly increasing plasma testosterone levels. We also determined that chronic 17α-E2 treatment did not alter plasma follicle-stimulating hormone or luteinizing hormone concentrations, which suggests 17α-E2 treatment does not alter gonadotropin-releasing hormone neuronal function. Sperm quantity, morphology, membrane integrity, and various motility measures were also unaffected by chronic 17α-E2 treatment in our studies. Lastly, two different approaches were used to evaluate male fertility in these studies. We found that chronic 17α-E2 treatment did not diminish the ability of male mice to impregnate female mice, or to generate successfully implanted embryos in the uterus. We conclude that chronic treatment with 17α-E2 at the dose most commonly employed in aging research does not adversely affect reproductive fitness in male mice, which suggests 17α-E2 does not extend lifespan or curtail disease parameters through tradeoff effects with reproduction.

The Potential Role of MicroRNA‐124‐3p in Growth, Development, and Reproduction of Schistosoma japonicum

The microRNA‐124‐3p plays an important role in regulating development and neurogenesis. Previous microRNA sequencing analyses of Schistosoma japonicum revealed sja-miR-124-3p differential expression patterns in schistosomes from different hosts and at different developmental stages. This study explores the regulatory role of sja-miR-124-3p in S. japonicum development and reproduction. Quantitative reverse-transcription PCR (qRT-PCR) showed that the expression level of sja-miR-124-3p in S. japonicum from resistant hosts, such as Microtus fortis, and unsuitable hosts, such as rats and water buffalo, was significantly higher than that in mice and yellow cattle at the same developmental stage. Overexpressing sja-miR-124-3p in infected mice led to a hepatic egg reduction rate of 36.97%, smaller egg granulomas in the livers, increased liver weight, subsided hepatocyte necrosis, and diminished inflammatory cell infiltration. The width of female worms increased but decreased in males. The vitelline cells were irregular, swollen, or fused. The teguments and ventral sucker of males and females were swollen and broken, but the morphological changes were particularly notable in males. qRT-PCR and dual-luciferase reporter assay system were used to confirm the in-silico-predicted target genes, S. japonicum DEAD-box ATP-dependent RNA helicase 1 (sjDDX1) and DNA polymerase II subunit 2 (sjPOLE2). Our results showed that RNA interference (RNAi)-mediated sjDDX1 silencing in mice provided a 24.55% worm reduction rate and an 18.36% egg reduction rate, but the difference was not significant (p > 0.05). Thus, our findings suggest that sja-miR-124-3p has an important role in growth, development, and reproduction in S. japonicum. All these results will greatly contribute toward providing important clues for searching vaccine candidates and new drug targets against schistosomiasis.

OUP accepted manuscript

STUDY QUESTION

Are taurine and its transporter TAUT associated with spermiogenesis and early embryo development?

SUMMARY ANSWER

Morphologically abnormal spermatozoa increased after local functional interference by intratesticular injection, and taurine depletion significantly reduced the normal embryo numbers in vivo and blastocyst formation rate in vitro.

WHAT IS KNOWN ALREADY

Taurine is one of the most abundant amino acids in the male reproductive system and it has been demonstrated that taurine can efficiently improve spermatogenic function in rat models of testicular injury. However, limited information is known about the role of taurine and its transporter TAUT in spermatogenesis and early embryo development.

STUDY DESIGN, SIZE, DURATION

Clinical characteristics from 110 couples who have experienced recurrent pregnancy loss (RPL) were collected from December 2014 to March 2018. According to whether a fetal heartbeat was seen in the previous pregnancy under ultrasonic monitoring, patients with RPL were divided into two groups: an RPL without heartbeat (pregnancy with no fetal heartbeat, ROH) group, and an RPL with heartbeat (one or more pregnancies with fetal heartbeat, RWH) group. Semen samples (21 ROH and 20 RWH) were finally used for metabolomic analysis. Furthermore, semen samples were obtained from 30 patients with teratozoospermia (normal sperm morphology <4%) seeking evaluation for infertility and 25 age-matched control subjects with normal semen quality for western blotting. Animal experiments were performed in CD-1/ICR mice.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Metabolomics was performed to determine the metabolic changes between the ROH and RWH groups. Sperm proteins from patients with teratozoospermia and healthy controls were extracted for detecting TAUT expression using western blot analysis. Immunofluorescence was used to characterize the localization of TAUT in the testis and ejaculated spermatozoa. Functional analysis in mice was performed by intratesticular injection of siRNAs or antagonist (β-alanine) and 5% β-alanine was provided in drinking water to 3-week-old male mice for 5 weeks with the aim of depleting taurine. Murine epididymal spermatozoa were stained with hematoxylin and eosin for morphological assessment. IVF and mating tests were performed in mice for assessing fertility.

MAIN RESULTS AND THE ROLE OF CHANCE

Metabolomic analysis demonstrated that the taurine content was lower in spermatozoa but higher in seminal plasma from the ROH than the RWH group. TAUT expression was lower in spermatozoa from patients with teratozoospermia than controls. Immunofluorescence showed that TAUT was localized to the manchette in mouse elongated spermatids functional analysis showed that morphologically abnormal spermatozoa increased after interference, and this defect increased after supplementation with 5% β-alanine but was improved by 5% taurine supplementation. Supplementation with 5% β-alanine significantly reduced the normal embryo number in the mouse uterus as well as blastocyst formation rate in vitro.

LARGE SCALE DATA

N/A

LIMITATIONS, REASONS FOR CAUTION

The sample size was low and larger cohorts are needed to confirm the positive effect of taurine on human sperm quality. A comprehensive safety examination should be performed to evaluate whether taurine is a possible treatment for teratozoospermia. Furthermore, the specific molecular mechanism of TAUT involvement in spermiogenesis remains to be clarified.

WIDER IMPLICATIONS OF THE FINDINGS

The study provides new insights into the role of taurine and its transporter TAUT in male reproduction and embryo development. The results also indicate that TAUT is a promising molecular candidate for the assessment of sperm quality, which may contribute to the diagnosis and treatment for teratozoospermia.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by grants from the National Natural Science Foundation of China (no. 81774075, 31900605, 81971451), Jiangsu Science and Technology Program Grant (BK20190654) and Maternal and child health scientific research of Jiangsu Province (F202121). The authors declare no competing financial interests.

Testis-expressed protein 33 is not essential for spermiogenesis and fertility in mice

Gene expression analyses have revealed that there are >2,300 testis-enriched genes in mice, and gene knockout models have shown that a number of them are responsible for male fertility. However, the functions of numerous genes have yet to be clarified. The aim of the present study was to identify the expression pattern of testis-expressed protein 33 (TEX33) in mice and explore the role of TEX33 in male reproduction. Reverse transcription-polymerase chain reaction and western blot assays were used to investigate the mRNA and protein levels of TEX33 in mouse testes during the first wave of spermatogenesis. Immunofluorescence analysis was also performed to identify the cellular and structural localization of TEX33 protein in the testes. Tex33 knockout mice were generated by CRISPR/Cas9 gene-editing. Histological analysis with hematoxylin and eosin or periodic acid-Schiff (PAS) staining, computer-assisted sperm analysis (CASA) and fertility testing, were also carried out to evaluate the effect of TEX33 on mouse spermiogenesis and male reproduction. The results showed that Tex33 mRNA and protein were exclusively expressed in mouse testes and were first detected on postnatal days 21–28 (spermiogenesis phase); their expression then remained into adulthood. Immunofluorescence analysis revealed that TEX33 protein was located in the spermatids and sperm within the seminiferous tubules of the mouse testes, and exhibited specific localization to the acrosome, flagellum and manchette during spermiogenesis. These results suggested that TEX33 may play a role in mouse spermiogenesis. However, Tex33 knockout mice presented no detectable difference in testis-to-body weight ratios when compared with wild-type mice. PAS staining and CASA revealed that spermatogenesis and sperm quality were normal in mice lacking Tex33. In addition, fertility testing suggested that the Tex33 knockout mice had normal reproductive functions. In summary, the findings of the present study indicate that TEX33 is associated with spermiogenesis but is not essential for sperm development and male fertility.

Quantitative Proteomic Analysis of Human Seminal Plasma from Normozoospermic and Asthenozoospermic Individuals

Seminal plasma is a complex mixture of secretions from various glands in the male genital tract. Compared to sperm cells, it contains important proteins that are both directly and indirectly associated with sperm motility. Here, we constructed quantitative proteomes of human seminal plasma from three normozoospermic and asthenozoospermic individuals. A total of 524 proteins were identified, and 366 of them were found to be quantified in all six samples. We first investigated the absolute expression features of these proteins and found that the variations of protein identification among different samples and other published datasets were mainly due to some lowly expressed proteins. By integration of various proteomic datasets and bioinformatics databases, we comprehensively annotated the biological functions, physiological originations, and disease associations of these proteins. We found that our dataset could benefit the studies of both male infertility and other male diseases. Finally, based on the relative expression values determined by chemical labeling, we identified a total of 29 differentially expressed proteins, which could be used as candidate targets for studying the molecular bases of sperm motility or developing precise diagnostic biomarkers of asthenozoospermia. We further successfully verified the expression trends of four representative proteins by Western blotting. Compared to a previous dataset based on label-free quantification, our results showed that most of the important proteins could be identified in the sample collected only once for each individual, providing the bases for personalized examination of seminal plasma proteins in clinic.

Caveolin-1 and MLRs: A potential target for neuronal growth and neuroplasticity after ischemic stroke

Ischemic stroke is a leading cause of morbidity and mortality worldwide. Thrombolytic therapy, the only established treatment to reduce the neurological deficits caused by ischemic stroke, is limited by time window and potential complications. Therefore, it is necessary to develop new therapeutic strategies to improve neuronal growth and neurological function following ischemic stroke. Membrane lipid rafts (MLRs) are crucial structures for neuron survival and growth signaling pathways. Caveolin-1 (Cav-1), the main scaffold protein present in MLRs, targets many neural growth proteins and promotes growth of neurons and dendrites. Targeting Cav-1 may be a promising therapeutic strategy to enhance neuroplasticity after cerebral ischemia. This review addresses the role of Cav-1 and MLRs in neuronal growth after ischemic stroke, with an emphasis on the mechanisms by which Cav-1/MLRs modulate neuroplasticity via related receptors, signaling pathways, and gene expression. We further discuss how Cav-1/MLRs may be exploited as a potential therapeutic target to restore neuroplasticity after ischemic stroke. Finally, several representative pharmacological agents known to enhance neuroplasticity are discussed in this review.

Effect of folate deficiency on promoter methylation and gene expression of Esr1, Cav1, and Elavl1, and its influence on spermatogenesis

This study aims to investigate the effect of folate deficiency on the male reproductive function and the underlying mechanism. A total of 269 screened participants from 421 recruitments were enrolled in this study. An animal model of folate deficiency was constructed. Folate concentration was measured in the ejaculate, and its association with semen parameters was then determined. The expression and promoter methylation status of ESR1, CAV1, and ELAVL1 were also evaluated. Results showed that seminal plasma folate level was significantly lower among subjects with azoospermia than those with normozoospermia. Low folate level was significantly correlated with low sperm concentration in men with normozoospermia. Folate deficiency significantly reduced the expression of ESR1, CAV1, and ELAVL1, which are critical to spermatogenesis. However, low folate levels did not increase the methylation levels of the promoter regions of ESR1, CAV1, and ELAVL1 in human sperm DNA. Thus, folate deficiency impairs spermatogenesis may partly due to inhibiting the expression of these genes. Thus future research should determine the significance of sufficient folate status in male fertilization and subsequent pregnancy outcomes.

MicroRNA-150 regulates steroidogenesis of mouse testicular Leydig cells by targeting STAR

Leydig cells are essential for male reproductive development throughout life. Production of androgens as well as intermediate steroids is tightly regulated. Although microRNAs (miRNAs) are suggested to play important roles in spermatogenesis, little is currently known regarding the regulation of steroidogenesis by miRNAs in Leydig cells. Here, we found that miR-150 was predominantly expressed in Leydig cells within mouse testis. Therefore, we determined steroidogenesis of the Leydig cells in which miR-150 was knocked down or overexpressed using miR-150 antagomir and agomir, respectively. Compared with negative control group, a significant increase of STAR expression was observed in miR-150 antagomir-treated Leydig cells. Conversely, STAR expression was significantly reduced in miR-150 agomir-transfected Leydig cells. Production of sex-steroid precursors and testosterone of Leydig cells was also negatively controlled by miR-150. We further identified Star as a target of miR-150 using luciferase reporter assay. Finally, we confirmed that miR-150 was necessary for steroidogenesis and spermatogenesis in vivo via intratesticular injection of miR-150 antagomir or agomir. Taken together, our studies suggest that miR-150 negatively regulates the expression of STAR and steroidogenesis of Leydig cells in mice.

Lipid rafts in immune signalling: current progress and future perspective

Lipid rafts are dynamic assemblies of proteins and lipids that harbour many receptors and regulatory molecules and so act as a platform for signal transduction. They float freely within the liquid-disordered bilayer of cellular membranes and can cluster to form larger ordered domains. Alterations in lipid rafts are commonly found to be associated with the pathogenesis of several human diseases and recent reports have shown that the raft domains can also be perturbed by targeting raft proteins through microRNAs. Over the last few years, the importance of lipid rafts in modulating both innate and acquired immune responses has been elucidated. Various receptors present on immune cells like B cells, T cells, basophils and mast cells associate with lipid rafts on ligand binding and initiate signalling cascades leading to inflammation. Furthermore, disrupting lipid raft integrity alters lipopolysaccharide-induced cytokine secretion, IgE signalling, and B-cell and T-cell activation. The objective of this review is to summarize the recent progress in understanding the role of lipid rafts in the modulation of immune signalling and its related therapeutic potential for autoimmune diseases and inflammatory disorders.