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Despite rapid evolution across eutherian mammals, the X-linked MIR-506 family miRNAs are located in a region flanked by two highly conserved protein-coding genes (SLITRK2 and FMR1) on the X chromosome. Intriguingly, these miRNAs are predominantly expressed in the testis, suggesting a potential role in spermatogenesis and male fertility. Here, we report that the X-linked MIR-506 family miRNAs were derived from the MER91C DNA transposons. Selective inactivation of individual miRNAs or clusters caused no discernible defects, but simultaneous ablation of five clusters containing 19 members of the MIR-506 family led to reduced male fertility in mice. Despite normal sperm counts, motility, and morphology, the KO sperm were less competitive than wild-type sperm when subjected to a polyandrous mating scheme. Transcriptomic and bioinformatic analyses revealed that these X-linked MIR-506 family miRNAs, in addition to targeting a set of conserved genes, have more targets that are critical for spermatogenesis and embryonic development during evolution. Our data suggest that the MIR-506 family miRNAs function to enhance sperm competitiveness and reproductive fitness of the male by finetuning gene expression during spermatogenesis.

Pachytene piRNA biogenesis is a hallmark of the germline, distinct from another wave of pre-pachytene piRNA biogenesis with regard to the lack of a secondary amplification process known as the Ping-pong cycle. However, the underlying molecular mechanism and the venue for the suppression of the Ping-pong cycle remain elusive. Here, we showed that a testis-specific protein, ADAD2, interacts with a TDRD family member protein RNF17 and is associated with P-bodies. Importantly, ADAD2 directs RNF17 to repress Ping-pong activity in pachytene piRNA biogenesis. The P-body localization of RNF17 requires the intrinsically disordered domain of ADAD2. Deletion of Adad2 or Rnf17 causes the mislocalization of each other and subsequent Ping-pong activity derepression, secondary piRNAs overproduced, and disruption of P-body integrity at the meiotic stage, thereby leading to spermatogenesis arrested at the round spermatid stage. Collectively, by identifying the ADAD2-dependent mechanism, our study reveals a novel function of P-bodies in suppressing Ping-pong activity in pachytene piRNA biogenesis.

Sertoli cells (SCs) support and nourish germ cells (GCs) through their crosstalk during spermatogenesis. However, the underlying epigenetic mechanism that ensures SCs' functions in this process remains unclear. Here, we report that UHRF1, a critical epigenetic regulator, is mainly expressed in human and mouse pre-mature SCs, and is essential for establishing Sertoli-Germ cell crosstalk. SC-specific UHRF1 knockout mice exhibit complete sterility with Sertoli cell (SC) proliferation and differentiation aberrance, blood-testis barrier (BTB) disruption, and immature germ cell (GC) sloughing. RNA sequencing and Whole Genome Bisulfite Sequencing (WGBS) revealed that many extracellular matrix (ECM)-related genes (e.g., Timp1, Trf, and Spp1) appeared upregulated with the DNA hypomethylation status in UHRF1-deficient SCs. Strikingly, overexpression of Timp1, Trf, and Spp1 in SCs in vitro and in vivo could phenocopy the SC-specific UHRF1-deficient mice. Our data demonstrated that UHRF1 regulates the transcriptional program of ECM-related genes in SCs and establishes SC-GC crosstalk.

Mammalian oviducts play an essential role in female fertility by picking up ovulated oocytes and transporting and nurturing gametes (sperm/oocytes) and early embryos. However, the relative contributions to these functions from various cell types within the oviduct remain controversial. The oviduct in mice deficient in two microRNA (miRNA) clusters (miR-34b/c and miR-449) lacks cilia, thus allowing us to define the physiological role of oviductal motile cilia. Here, we report that the infundibulum without functional motile cilia failed to pick up the ovulated oocytes. In the absence of functional motile cilia, sperm could still reach the ampulla region, and early embryos managed to migrate to the uterus, but the efficiency was reduced. Further transcriptomic analyses revealed that the five messenger ribonucleic acids (mRNAs) encoded by miR-34b/c and miR-449 function to stabilize a large number of mRNAs involved in cilium organization and assembly and that Tubb4b was one of their target genes. Our data demonstrate that motile cilia in the infundibulum are essential for oocyte pickup and thus, female fertility, whereas motile cilia in other parts of the oviduct facilitate gamete and embryo transport but are not absolutely required for female fertility.

There are no non-hormonal male contraceptives currently on the market despite decades of efforts toward the development of "male pills". Here, we report that triptonide, a natural compound purified from the Chinese herb Tripterygium Wilfordii Hook F displays reversible male contraceptive effects in both mice and monkeys. Single daily oral doses of triptonide induces deformed sperm with minimal or no forward motility (close to 100% penetrance) and consequently male infertility in 3-4 and 5-6 weeks in mice and cynomolgus monkeys, respectively. Male fertility is regained in ~4-6 weeks after cessation of triptonide intake in both species. Either short- or long-term triptonide treatment causes no discernable systematic toxic side effects based on histological examination of vital organs in mice and hematological and serum biochemical analyses in monkeys. Triptonide appears to target junction plakoglobin and disrupts its interactions with SPEM1 during spermiogenesis. Our data further prove that targeting late spermiogenesis represents an effective strategy for developing non-hormonal male contraceptives.

DNA methylation, repressive histone marks, and PIWI-interacting RNA (piRNA) are essential for the control of retrotransposon silencing in the mammalian germline. However, it remains unknown how these repressive epigenetic pathways crosstalk to ensure retrotransposon silencing in the male germline. Here, we show that UHRF1 is responsible for retrotransposon silencing and cooperates with repressive epigenetic pathways in male germ cells. Conditional loss of UHRF1 in postnatal germ cells causes DNA hypomethylation, upregulation of retrotransposons, the activation of a DNA damage response, and switches in the global chromatin status, leading to complete male sterility. Furthermore, we show that UHRF1 interacts with PRMT5, an arginine methyltransferase, to regulate the repressive histone arginine modifications (H4R3me2s and H3R2me2s), and cooperates with the PIWI pathway during spermatogenesis. Collectively, UHRF1 regulates retrotransposon silencing in male germ cells and provides a molecular link between DNA methylation, histone modification, and the PIWI pathway in the germline.

Nonobstructive azoospermia (NOA) is considered to be the most severe form of male infertility. Meiotic arrest is one of the major causes of NOA and can be caused by single gene mutations. Here, a novel homozygous missense mutation (c.131G>T) in the MEI1 gene was identified through whole exome sequencing in a Chinese men with NOA caused by meiotic arrest. Bioinformatics and genetic analysis predicted that this novel mutation may be deleterious. Our findings confirm that spermatogenesis is arrested at the primary spermatocyte stage, with defective programed DNA double‐strand breaks (DSBs) formation. In vitro functional analysis revealed that the defects of DSBs formation may be a result of a lower expression level of MEI1 protein in the mutant. Therefore, the NOA in this patient is likely caused by the single novel mutation in the MEI1 gene leading to meiotic arrest. Our report expands the mutation spectrum of MEI1 and provides new evidence that the MEI1 gene may serve as a diagnostic marker for genetic counseling in NOA patients. [ABSTRACT FROM AUTHOR]

Eggs of teleost fish, unlike those of many other animals, allow sperm entry only at a single site, a narrow canal in the egg's chorion called the micropyle. In some fish (e.g., flounder, herring, and Alaska pollock), the micropyle is a narrow channel in the chorion, with or without a shallow depression around the outer opening of micropyle. In some other fish (e.g., salmon, pufferfish, cod, and medaka), the micropyle is like a funnel with a conical opening. Eggs of all the above fish have a glycoprotein tightly bound to the chorion surface around the micropyle. This glycoprotein directs spermatozoa into the micropylar canal in a Ca2+-dependent manner. This substance, called the micropylar sperm attractant or MISA, increases fertilization efficiency and is essential in herring. In flounder, salmon, and perhaps medaka, fertilization is possible without MISA, but its absence makes fertilization inefficient because most spermatozoa swim over the micropyle without entering it. The mechanism underlying sperm-MISA interactions is yet to be determined, but at least in herring the involvement of Ca2+ and K+ channel proteins, as well as CatSper and adenylyl cyclase, is very likely. In some other fish (e.g., zebrafish, loach, and goldfish), the chorion around the micropyle is deeply indented (e.g., zebrafish and loach) or it has radially or spirally arranged grooves around the outer opening of the micropyle (e.g., goldfish). MISA is absent from the eggs of these fish and sperm entry into micropylar canal seems to be purely physical.

This study aims to investigate whether transfection of miR‐486 in the corpus cavernosum of spontaneously hypertensive rats (SHR) can improve erectile function and its mechanism. SHR penile cavernous smooth muscle cells were divided into control group, mimic negative control transfection group, inhibitor negative control transfection group, miR‐486 mimic transfection group, and miR‐486 inhibitor transfection group. miR‐486 mimic (50 nM), miR‐486 inhibitor (100 nM), and corresponding negative control preparation were transfected into the corresponding groups of cells. The mRNA expressions of miR‐486, TGF‐β1, Collagen I, and Collagen III in each group were detected after transfection. Twelve 12‐week‐old healthy male SHR and 12 WKY rats were randomly divided into WKY control group, SHR control group, SHR + Agomir negative control (NC) group, and SHR + miR‐486 Agomir group. In the SHR + miR‐486 Agomir group, penile cavernosa was transfected with miR‐486 agonist. Penile sponge internal pressure (ICPmax)/mean arterial pressure (MAP), the expression of miR‐486, the ratio of smooth muscle to collagen (SM/C), and the expression of TGF‐β1, Collagen I, and Collagen III in penile cavernosum tissues were determined. Compared with the control group, the expressions of TGF‐β1, Collagen I, and Collagen Ⅲ in the miR‐486 mimic transfection group of SHR rat corpus cavernosum smooth muscle cells were significantly decreased, while those in the miR‐486 inhibitor transfection group were significantly increased (P < 0.05). The ratios of ICPmax/MAP and SM/C in the SHR group were significantly lower than those in the WKY group and in the SHR + miR‐486 Agomir group were significantly higher than those in the SHR group and the SHR + Agomir NC group (P < 0.05). The expressions of TGF‐β1, Collagen I, and Collagen Ⅲ in SHR group were significantly increased compared with those in WKY group, while those in SHR + miR‐486 Agomir group were significantly lower than those in SHR group and SHR + Agomir NC group (P < 0.05). The upregulation of the expression of miR‐486 in the corpus cavernosum of SHR rats can inhibit fibrosis of the corpus cavernosum and improve erectile function. [ABSTRACT FROM AUTHOR]