During human spermatogenesis, germ cells undergo dynamic changes in chromatin organization/re-packaging and in transcriptomes. In order to better understand the underlying mechanism(s), scATAC-Seq of 5376 testicular cells from 3 normal men were performed. Data were analyzed in parallel with the scRNA-Seq data of human testicular cells. In all, 10 germ cell types associated with spermatogenesis and 6 testicular somatic cell types were identified, along with 142 024 peaks located in promoter, genebody and CpG Island. We had examined chromatin accessibility of all chromosomes, with chromosomes 19 and 17 emerged as the leading chromosomes that displayed high chromatin accessibility. In accessible chromatin regions, transcription factor-binding sites were identified and specific motifs with high frequencies at different spermatogenesis stages were detected, including CTCF, BORIS, NFY, DMRT6, EN1, ISL1 and GLI3. Two most remarkable observations were noted. First, TLE3 was specifically expressed in differentiating spermatogonia. Second, PFN4 was found to be involved in actin cytoskeletal organization during meiosis. More important, unique regions upstream of PFN4 and TLE3 were shown to display high accessibility, illustrating their significance in supporting human spermatogenesis.

During meiosis, telomeres attach to the nuclear envelope (NE) to promote homologous chromosome moving, pairing, synapsis, and recombination. The telomere-NE attachment is mediated by SUN1, TERB1-TERB2-MAJIN (TTM complex), and TRF1. The interaction of the TTM complex with shelterin is mediated by TERB1 and TRF1, but how SUN1 interacts with the TTM complex is not yet fully understood. In this study, we found that SUN1 not only interacted with TERB1 but also interacted with MAJIN, and the interaction of SUN1 with MAJIN is stronger than TERB1. We also found that SUN1 interacted with SPDYA, an activator of CDK2. The binding sites of MAJIN and SPDYA at SUN1 were mapped, and both MAJIN and SPDYA bound to the N-terminal domain of SUN1 and the two binding sites were close to each other. Furthermore, SPDYA bound to SUN1 via the Ringo domain and recruited CDK2 to SUN1. Then, we found that the interaction of SUN1 with MAJIN was decreased by the CDK2 inhibitors. Taken together, our results provide the possible mechanism of SUN1, MAJIN, and SPDYA-CDK2 in promoting the telomere-NE attachment during meiosis.

Environmental toxicants, such as cadmium, found in foods, water and consumer products are known to induce male reproductive dysfunction. However, the underlying molecular mechanism(s) by which cadmium-induced Sertoli cell injury as manifested by a disruption of the blood-testis barrier remains unknown. Interestingly, one of the primary targets of cadmium toxicity in the testis is the cytoskeletons of the Sertoli cells, which, in turn, impedes cell junctions in the seminiferous epithelium. In order to expand these earlier observations and to provide a roadmap for future studies, we embarked a study using RNA-Seq to identify the pertinent genes involved in cadmium-induced Sertoli cell injury. Using bioinformatics analyses, multiple gene sets that regulated actin and microtubule (MT) cytoskeletons were identified along with components of the MAPK (mitogen activated protein kinase) signaling protein and several signaling pathways. More important, we have also discovered that while the gene expression of p38-MAPK (also JNK or c-Jun) was considerably up- or down-regulated during cadmium-induced Sertoli cell injury, the activated (phosphorylated) form was up-regulated. Importantly, doramapimod (BIRB 796), a specific p38-MARK inhibitor, that was shown to selectively block cadmium-induced p-p38 MAPK activation via phosphorylation in Sertoli cells, was indeed capable of blocking cadmium-induced Sertoli cell injury including disruption of the Sertoli cell-permeability barrier function, disruptive distribution of BTB-associated proteins, and disruptive organization of the actin and MT cytoskeletons. These data provide a helpful source of information for investigators to probe the role of signaling proteins and/or cascades, besides MAPKs, that likely utilized by cadmium to induce reproductive dysfunction.

Male infertility is a rising problem around the world. Often the cause of male infertility is unclear, and this hampers diagnosis and treatment. Spermatogenesis is a complex process under sophisticated regulation by many testis‐specific genes. Here, we report the testis‐specific gene 1700102P08Rik is conserved in both the human and mouse and highly expressed in spermatocytes. To investigate the role of 1700102P08Rik in male fertility, knockout mice were generated by CRISPR‐Cas9. 1700102P08Rik knockout male mice were infertile with smaller testis and epididymis, but female knockout mice retained normal fertility. Spermatogenesis in the 1700102P08Rik knockout male mouse was arrested at the spermatocyte stage, and no sperm were found in the epididymis. The deletion of 1700102P08Rik causes apoptosis in the testis but did not affect the serum concentration of testosterone, luteinizing hormone, and follicle‐stimulating hormone or the synapsis and recombination of homologous chromosomes. We also found that 1700102P08Rik is downregulated in spermatocyte arrest in men. Together, these results indicate that the 1700102P08Rik gene is essential for spermatogenesis and its dysfunction leads to male infertility.

Glycine is the simplest amino acid in living organisms and plays important roles in biology and medicine. However, few biosensors for glycine sensing have been reported. Herein, we present a facile strategy to construct dopaminemodified AuCu bimetallic nanoclusters (denoted as AuCu NC− DA) as charge transfer-based biosensors for highly sensitive glycine sensing. The AuCu NCs stabilized by bovine serum albumin (BSA) exhibited a fluorescence maximum at 400 nm. Because of the high affinity of BSA for dopamine (DA), the surface of the AuCu NCs was modified with DA without any complicated chemical reactions, resulting in fluorescence quenching through a charge transfer process. Among 20 amino acids, AuCu NC−DA exhibited an off/on fluorescence switching response specifically toward glycine through the formation of hydrogen bonds with oxidized DA, which inhibited the charge transfer process, leading to the emergence of a new emission peak at 475 nm. Spectroscopic and thermodynamic results combined with molecular docking analyses provided comprehensive understanding of the sensing mechanism. Furthermore, we showed that AuCu NC−DA was able to sense glycine in cells by imaging. Finally, the practicability of AuCu NC−DA for glycine detection was validated in milk drink samples. This study presents a promising type of a charge transfer-based sensor.