Applications of single-cell RNA sequencing in spermatogenesis and molecular evolution.

Spermatogenic cell heterogeneity is determined by the complex process of spermatogenesis differentiation. However, effectively revealing the regulatory mechanisms underlying mammalian spermatogenic cell development and differentiation via traditional methods is difficult. Advances in technology have led to the emergence of many single-cell transcriptome sequencing protocols, which have partially addressed these challenges. In this review, we detail the principles of 10x Genomics technology and summarize the methods for downstream analysis of single-cell transcriptome sequencing data. Furthermore, we explore the role of single-cell transcriptome sequencing in revealing the heterogeneity of testicular ecological niche cells, delineating the establishment and disruption of testicular immune homeostasis during human spermatogenesis, investigating abnormal spermatogenesis in humans, and, ultimately, elucidating the molecular evolution of mammalian spermatogenesis.

A multi-omics analysis of viral nucleic acid poly(I:C) responses to mammalian testicular stimulation.

The male reproductive system has a standard immune response regulatory mechanism, However, a variety of external stimuli, including viruses, bacteria, heat, and medications can damage the testicles and cause orchitis and epididymitis. It has been shown that various RNA viruses are more likely to infect the testis than DNA viruses, inducing orchitis and impairing testicular function. It was found that local injection of the viral RNA analog poly(I:C) into the testes markedly disrupted the structure of the seminiferous tubules, accompanied by apoptosis and inflammation. Poly(I:C) mainly inhibited the expression of testosterone synthesis-associated proteins, STAR and MGARP, and affected the synthesis and metabolism of amino acids and lipids in the testis. This led to the disruption of the metabolite levels in the testis of mice, thus affecting the normal spermatogenesis process. The present study analyzed the acute inflammatory response of the testis to viral infection using a multi-omics approach. It provides insights into how RNA virus infection impairs testicular function and offers a theoretical basis for future studies on immune homeostasis and responses under stress conditions in male reproduction.

Induction of lung progenitor cell-like organoids by porcine pluripotent stem cells.

Organoids are in vitro 3D models that are generated using stem cells to study organ development and regeneration. Despite the extensive research on lung organoids, there is limited information on pig lung cell generation or development. Here, we identified five epithelial cell types along with their characteristic markers using scRNA-seq. Additionally, we found that NKX2.1 and FOXA2 acted as the crucial core transcription factors in porcine lung development. The presence of SOX9/SOX2 double-positive cells was identified as a key marker for lung progenitor cells. The Monocle algorithm was used to create a pseudo-temporal differentiation trajectory of epithelial cells, leading to the identification of signaling pathways related to porcine lung development. Moreover, we established the differentiation method from porcine pluripotent stem cells (pPSCs) to SOX17+ FOXA2+ definitive endoderm (DE) and NKX2.1+ FOXA2+ CDX2- anterior foregut endoderm (AFE). The AFE is further differentiated into lung organoids while closely monitoring the differentiation process. We showed that NKX2.1 overexpression facilitated the induction of lung organoids and supported subsequent lung differentiation and maturation. This model offers valuable insights into studying the interaction patterns between cells and the signaling pathways during the development of the porcine lung.

PLZF protein forms a complex with protein TET1 to target TCF7L2 in undifferentiated spermatogonia.

The transcription factor promyelocytic leukemia zinc finger (PLZF, also known as ZBTB16) is critical for the self-renewal of spermatogonial stem cells (SSCs). However, the function of PLZF in SSCs is not clear. Here, we found that PLZF acted as an epigenetic regulator of stem cell maintenance and self-renewal of germ cells. The PLZF protein interacts with the ten-eleven translocation 1 (TET1) protein and subsequently acts as a modulator to regulate the expression of self-renewal-related genes. Furthermore, Transcription Factor 7-like 2 (TCF7L2) is promoted by the coordination of PLZF and Tri-methylation of lysine 4 on histone H3 (H3K4me3). In addition, testicular single-cell sequencing indicated that TCF7L2 is commonly expressed in the PLZF cluster. We demonstrated that PLZF directly targets TCF7L2 and alters the landscape of histone methylation in the SSCs nucleus. Meanwhile, the RD domain and Zn finger domain of PLZF synergize with H3K4me3 and directly upregulate TCF7L2 expression at the transcriptional level. Additionally, we identified a new association between PLZF and the histone methyltransferase EZH2 at the genomic level. Our study identified a new association between PLZF and H3K4me3, established the novel PLZF&TET1-H3K4me3-TCF7L2 axis at the genomic level which regulates undifferentiated spermatogonia, and provided a platform for studying germ cell development in male domestic animals.

Rapid conversion of porcine pluripotent stem cells into macrophages with chemically defined conditions.

A renewable source of porcine macrophages derived from pluripotent stem cells (PSCs) would be a valuable alternative to primary porcine alveolar macrophages (PAMs) in the research of host-pathogen interaction mechanisms. We developed an efficient and rapid protocol, within 11 days, to derive macrophages from porcine PSCs (pPSCs). The pPSC-derived macrophages (pPSCdMs) exhibited molecular and functional characteristics of primary macrophages. The pPSCdMs showed macrophage-specific surface protein expression and macrophage-specific transcription factors, similar to PAMs. The pPSCdMs also exhibited the functional characteristics of macrophages, such as endocytosis, phagocytosis, porcine respiratory and reproductive syndrome virus infection and the response to lipopolysaccharide stimulation. Furthermore, we performed transcriptome sequencing of the whole differentiation process to track the fate transitions of porcine PSCs involved in the signaling pathway. The activation of transforming growth factor beta signaling was required for the formation of mesoderm and the inhibition of the transforming growth factor beta signaling pathway at the hematopoietic endothelium stage could enhance the fate transformation of hematopoiesis. In summary, we developed an efficient and rapid protocol to generate pPSCdMs that showed aspects of functional maturity comparable with PAMs. pPSCdMs could provide a broad prospect for the platforms of host-pathogen interaction mechanisms.

[BLOC1S1 promotes proliferation of goat spermatogonial stem cells].

With the rapid development of gene editing technology, the study of spermatogonial stem cells (SSCs) holds great significance in understanding spermatogenesis and its regulatory mechanism, developing transgenic animals, gene therapy, infertility treatment and protecting rare species. Biogenesis of lysosome-related organelles complex 1 subunit 1 (BLOC1S1) is believed to have anti-brucella potential. Exploring the impack of BLOC1S1 on goat SSCs not only helps investigate the ability of BLOC1S1 to promote SSCs proliferation, but also provides a cytological basis for disease-resistant breeding research. In this study, a BLOC1S1 overexpression vector was constructed by homologous recombination. The BLOC1S1 overexpression cell line of goat spermatogonial stem cells was successfully constructed by lentivirus packaging, transfection and puromycin screening. The overexpression efficiency of BLOC1S1 was found to be 18 times higher using real time quantitative PCR (RT-qPCR). Furthermore, the results from cell growth curve analysis, flow cytometry for cell cycle detection, and 5-ethynyl-2'-deoxyuridine (EdU) staining showed that BLOC1S1 significantly increased the proliferation activity of goat SSCs. The results of RT-qPCR, immunofluorescence staining and Western blotting analyses revealed up-regulation of proliferation-related genes (PCNA, CDK2, CCND1), and EIF2S3Y, a key gene regulating the proliferation of spermatogonial stem cells. These findings strongly suggest that the proliferative ability of goat SSCs can be enhanced through the EIF2S3Y/ERK pathway. In summary, this study successfully created a goat spermatogonial stem cell BLOC1S1 overexpression cell line, which exhibited improved proliferation ability. This research laid the groundwork for exploring the regulatory role of BLOC1S1 in goat spermatogonia and provided a cell platform for further study into the biological function of BLOC1S1. These findings also establish a foundation for breeding BLOC1S1 overexpressing goats.

UCHL1 maintains microenvironmental homeostasis in goat germline stem cells.

Spermatogonial stem cells (SSCs) play a crucial role in mammalian spermatogenesis and maintain the stable inheritance of the germline in livestock. However, stress and bacterial or viral infections can disrupt immune homeostasis of the testes, thereby leading to spermatogenesis destruction and infertility, which severely affects the health and productivity of mammals. This study aimed to explore the effect of ubiquitin C-terminal hydrolase L1 (UCHL1) knockdown (KD) in goat SSCs and mouse testes and investigate the potential anti-inflammatory function of UCHL1 in a poly(I:C)-induced inflammation model to maintain microenvironmental homeostasis. In vitro, the downregulation of UCHL1 (UCHL1 KD) in goat SSCs increased the expression levels of apoptosis and inflammatory factors and inhibited the self-renewal and proliferation of SSCs. In vivo, the structure of seminiferous tubules and spermatogenic cells was disrupted after UCHL1 KD, and the expression levels of apoptosis- and inflammation-related proteins were significantly upregulated. Furthermore, UCHL1 inhibited the TLR3/TBK1/IRF3 pathway to resist poly(I:C)-induced inflammation in SSCs by antagonizing HSPA8 and thus maintaining SSC autoimmune homeostasis. Most importantly, the results of this study showed that UCHL1 maintained immune homeostasis of SSCs and spermatogenesis. UCHL1 KD not only inhibited the self-renewal and proliferation of goat SSCs and spermatogenesis but was also involved in the inflammatory response of goat SSCs. Additionally, UCHL1 has an antiviral function in SSCs by antagonizing HSPA8, which provides an important basis for exploring the specific mechanisms of UCHL1 in goat spermatogenesis.

[Progress on mRNA vaccine for the prevention of major infectious diseases in humans and animals].

A large number of studies have demonstrated that mRNA vaccine has been characterized as a technique with good safety, strong immunogenicity and high developmental potential, which makes it have broad prospects in immunotherapy. In recent years, the stability and in vivo delivery efficiency of mRNA vaccines have been largely addressed by the progresses in mRNA engineering and delivery innovation. And some mRNA vaccines are now clinical approved or in preclinical trials. Here, we summarize current knowledge on the research advances, technology, and application in major infectious diseases in humans and animals of mRNA vaccines, with the aim to provide a reference for improving the development of novel mRNA vaccines.

Genomic selection analysis of morphological and adaptation traits in Chinese indigenous dog breeds.

The significant morphological differences and abundant germplasm resources of Chinese indigenous dog breeds can be attributed to the diverse geographical environment, including plateaus, mountains, and a long history of raising dogs. The combination of both natural and artificial selection during the past several thousand years has led to hundreds of dog breeds with distinct morphological traits and environmental adaptations. China is one of the earliest countries to domesticate dogs and there are more than 50 ancient indigenous dog breeds. In this study, the run of homozygosity (ROH) and proportion of the autosomal genome covered by ROHs (FROH) were calculated for 10 dog breeds that are the most representative Chinese indigenous dogs based on 170K SNP microarray. The results of FROH showed that the Chuandong hound dogs (HCSSC) have the highest level of inbreeding among the tested breeds. The inbreeding in HCSSC occurred more recently than the Liangshan dogs (SCLSQ) dogs because of more numbers of long ROHs in HCSSC dogs, and the former also have higher inbreeding degree. In addition, there are significant differences in the inbreeding degree among different subpopulations of the same breed, such as the Thin dogs from Shaanxi and Shandong province. To explore genome-wide selection signatures among different breeds, including coat color, ear shape, and altitude adaptability, we performed genome selection analyses of FST and cross population extended haplotype homozygosity (XP-EHH). For the coat color, the FST analysis between Xiasi dogs (XSGZ) and HCSSC dogs was performed and identified multiple genes involved in coat color, hair follicle, and bone development, including MC1R, KITLG, SOX5, RSPO2, and TBX15. For the plateau adaptability, we performed FST and XP-EHH analyses between dogs from Tibet (Tibetan Mastiffs and Nyingchi dogs) and plain regions (Guangxi Biwei dogs GXBWQ and Guandong Sharpei dogs). The results showed the EPAS1 gene in dogs from Tibet undergo strong selection. Multiple genes identified for selection signals based on different usage of dogs. Furthermore, the results of ear shape analyses showed that MSRB3 was likely to be the main gene causing the drop ear of domestic dogs. Our study provides new insights into further understanding of Chinese indigenous dogs.

Interaction between Mesenchymal Stem Cells and Immune Cells during Bone Injury Repair.

Fractures are the most common large organ trauma in humans. The initial inflammatory response promotes bone healing during the initial post-fracture phase, but chronic and persistent inflammation due to infection or other factors does not contribute to the healing process. The precise mechanisms by which immune cells and their cytokines are regulated in bone healing remain unclear. The use of mesenchymal stem cells (MSCs) for cellular therapy of bone injuries is a novel clinical treatment approach. Bone progenitor MSCs not only differentiate into bone, but also interact with the immune system to promote the healing process. We review in vitro and in vivo studies on the role of the immune system and bone marrow MSCs in bone healing and their interactions. A deeper understanding of this paradigm may provide clues to potential therapeutic targets in the healing process, thereby improving the reliability and safety of clinical applications of MSCs to promote bone healing.

Eif2s3y alleviated LPS-induced damage to mouse testis and maintained spermatogenesis by negatively regulating Adamts5.

Eif2s3y (eukaryotic translation initiation factor 2, subunit 3, structural gene Y-linked, Eif2s3y) is an essential gene for spermatogenesis. Early studies have shown that Eif2s3y can promote the proliferation of spermatogonial stem cells (SSCs) and can replace the Y chromosome together with sex-determining region Y (Sry) to transform SSCs into round spermatozoa. We injected lentiviral particles into the seminiferous tubules of mouse testes by sterile surgery surgically to establish overexpressing Eif2s3y testes. And then the mice were intraperitoneally injected with LPS to established the model of testis inflammation. Through RNA sequencing, qRT-PCR analysis, Western blot, co-culture etc., we found that Eif2s3y alleviated LPS-induced damage in mouse testes and maintained spermatogenesis. In testes with Eif2s3y overexpression, the seminiferous tubules were more regularly organized after exposure to LPS compared with the control. Eif2s3y performs its function by negatively regulating Adamts5 (a disintegrin and metalloproteinase containing a thrombospondin-1 motif), an extracellular matrix-degrading enzyme. ADAMTS5 shows a disruptive effect when the testis is exposed to LPS. Overexpression of Eif2s3y inhibited the TLR4/NFκB signaling pathway in the testis in response to LPS. Generally, our research shows that Eif2s3y protects the testis from LPS and maintains spermatogenesis by negatively regulating Adamts5.

Liraglutide ameliorates diabetic-induced testicular dysfunction in male rats: role of GLP-1/Kiss1/GnRH and TGF-ß/Smad signaling pathways.

Introduction: Glucagon-like peptide -1 (GLP-1) is released by intestinal cells to stimulate glucose-dependent insulin release from the pancreas. GLP-1 has been linked to ameliorating obesity and/or diabetic complications as well as controlling reproductive function. Liraglutide is a GLP-1 receptor agonist (GLP-1RA) with 97% homology with GLP-1. The main objective of this study was to investigate the ameliorative role of liraglutide in diabetic-induced reproductive dysfunction in male rats. Methods: Rats were randomly allocated into 3 groups; a control group, a diabetic group, and a liraglutide-treated diabetic group. Results: In the diabetic group, a significant increase in BMI, FBG, HbA1c, HOMA-IR, TC, TAG, LDL, IL6, TNFα, and MDA, as well as decreased serum insulin, HDL, GSH, total testosterone, LH, and FSH, were shown compared to the control group. Furthermore, A significant downregulation in relative hypothalamic gene expression of GLP-1R, PPAR-α, PGC-1α, kiss, kiss1R, leptin, leptin R, GnRH GLP-1R, testicular PGC-1α, PPARα, kiss1, kiss1R, STAR, CYP17A1, HSD17B3, CYP19A, CYP11A1, and Smad7, as well as upregulation in hypothalamic GnIH and testicular TGF- ß and Smad2 expression, were noticed compared to the control group. Liraglutide treatment significantly improved such functional and structural reproductive disturbance in diabetic rats. Conclusion: GLP-1RAs ameliorated the deleterious effects of diabetes on reproductive function by targeting GLP-1/leptin/kiss1/GnRH, steroidogenesis, and TGF- ß/Smad pathways.

Remodeling of Gut Microbiota by Probiotics Alleviated Heat Stroke-Induced Necroptosis in Male Germ Cells.

SCOPE: Systemic heat stress (or heatstroke; HS) induces germ cell death and spermatogenesis disorders in men and male mammals. Also, it affects the immune environment of the circulatory system promoting gut inflammation and intestinal permeability, leading to pathogenic infection. In this study, the crosstalk between the gut and testis (gut-testis axis) under HS is explored, by examining the effects of intestinal immune status on the health of the male reproductive system in mice. METHODS AND RESULTS: A mouse model of systemic heat stress is established to investigate the effect of probiotics on testis health. The results reveal that pro-inflammatory factor receptor activation pathway and pathogen infection response pathway are significantly upregulated in HS testes, leading to necroptosis, while pro-inflammatory factor and endotoxin are detected locally in the intestine and then entered the blood. The study then uses probiotics to intervene in gut microbiota, which results in milder gut microbial changes, lower inflammatory responses in the HS gut, and less necroptosis in the HS testes. CONCLUSION: Probiotics-based remodeling of gut microbiota (GM) reduces the proliferation of abnormal bacteria and decreases the spread of gut-derived inflammatory mediators into the blood circulation under long-term systemic heat stress, which relieves inflammation on germ cells.

Mesenchymal Stem Cells Pretreated with Collagen Promote Skin Wound-Healing.

The existing treatment modalities for skin injuries mainly include dressings, negative-pressure wound treatment, autologous skin grafting, and high-pressure wound treatment. All of these therapies have limitations such as high time cost, the inability to remove inactivated tissue in a timely manner, surgical debridement, and oxygen toxicity. Mesenchymal stem cells have a unique self-renewal ability and wide differentiation potential, and they are one of the most promising stem cell types in cell therapy and have great application prospects in the field of regenerative medicine. Collagen exerts structural roles by promoting the molecular structure, shape, and mechanical properties of cells, and adding it to cell cultures can also promote cell proliferation and shorten the cell doubling time. The effects of collagen on MSCs were examined using Giemsa staining, EdU staining, and growth curves. Mice were subjected to allogeneic experiments and autologous experiments to reduce individual differences; all animals were separated into four groups. Neonatal skin sections were detected by HE staining, Masson staining, immunohistochemical staining, and immunofluorescence staining. We found that the MSCs pretreated with collagen accelerated the healing of skin wounds in mice and canines by promoting epidermal layer repair, collagen deposition, hair follicle angiogenesis, and an inflammatory response. Collagen promotes the secretion of the chemokines and growth factors associated with skin healing by MSCs, which positively influences skin healing. This study supports the treatment of skin injuries with MSCs cultured in medium with collagen added.

Transcription factor Dmrt1 triggers the SPRY1-NF-κB pathway to maintain testicular immune homeostasis and male fertility.

Bacterial or viral infections, such as Brucella, mumps virus, herpes simplex virus, and Zika virus, destroy immune homeostasis of the testes, leading to spermatogenesis disorder and infertility. Of note, recent research shows that SARS-CoV-2 can infect male gonads and destroy Sertoli and Leydig cells, leading to male reproductive dysfunction. Due to the many side effects associated with antibiotic therapy, finding alternative treatments for inflammatory injury remains critical. Here, we found that Dmrt1 plays an important role in regulating testicular immune homeostasis. Knockdown of Dmrt1 in male mice inhibited spermatogenesis with a broad inflammatory response in seminiferous tubules and led to the loss of spermatogenic epithelial cells. Chromatin immunoprecipitation sequencing (ChIP-seq) and RNA sequencing (RNA-seq) revealed that Dmrt1 positively regulated the expression of Spry1, an inhibitory protein of the receptor tyrosine kinase (RTK) signaling pathway. Furthermore, immunoprecipitation-mass spectrometry (IP-MS) and co-immunoprecipitation (Co-IP) analysis indicated that SPRY1 binds to nuclear factor kappa B1 (NF-κB1) to prevent nuclear translocation of p65, inhibit activation of NF-κB signaling, prevent excessive inflammatory reaction in the testis, and protect the integrity of the blood-testis barrier. In view of this newly identified Dmrt1- Spry1-NF-κB axis mechanism in the regulation of testicular immune homeostasis, our study opens new avenues for the prevention and treatment of male reproductive diseases in humans and livestock.

[Development of porcine induced pluripotent stem cells with a CD163 reporter system].

As main recipient cells for porcine reproductive and respiratory syndrome virus (PRRSV), porcine alveolar macrophage (PAM) are involved in the progress of several highly pathogenic virus infections. However, due to the fact that the PAM cells can only be obtained from primary tissues, research on PAM-based virus-host interactions remains challenging. The improvement of induced pluripotent stem cells (iPSCs) technology provides a new strategy to develop IPSCs-derived PAM cells. Since the CD163 is a macrophage-specific marker and a validated receptor essential for PRRSV infection, generation of stable porcine induced pluripotent stem cells lines containing CD163 reporter system play important roles in the investigation of IPSCs-PAM transition and PAM-based virus-host interaction. Based on the CRISPR/Cas9- mediated gene editing system, we designed a sgRNA targeting CD163 locus and constructed the corresponding donor vectors. To test whether this reporter system has the expected function, the reporter system was introduced into primary PAM cells to detect the expression of RFP. To validate the low effect on stem cell pluripotency, we generated porcine iPSC lines containing CD163 reporter and assessed the pluripotency through multiple assays such as alkaline phosphatase staining, immunofluorescent staining, and EdU staining. The red-fluorescent protein (RFP) expression was detected in CD163-edited PAM cells, suggesting that our reporter system indeed has the ability to reflect the expression of gene CD163. Compared with wild-type (WT) iPSCs, the CD163 reporter-iPSCs display similar pluripotency-associated transcription factors expression. Besides, cells with the reporter system showed consistent cell morphology and proliferation ability as compared to WT iPSCs, indicating that the edited-cells have no effect on stem cell pluripotency. In conclusion, we generated porcine iPSCs that contain a CD163 reporter system. Our results demonstrated that this reporter system was functional and safe. This study provides a platform to investigate the iPS-PAM development and virus-host interaction in PAM cells.

MMPs, ADAMs and ADAMTSs are associated with mammalian sperm fate.

Metalloproteinases include matrix metalloproteinases and disintegrin metalloproteinases. They are important members of the ECM degradation and reconstruction process and are associated with tissue development and disease. The ECM is a three-dimensional network of large molecules consisting of a variety of proteins. It is a physical scaffold for organs, and all types of cells can be found within the ECM. The testicle, where sperm are produced, is an organ that is constantly in dynamic flux. Metalloproteinases can regulate testicular tissue development and the maturation of sperm by affecting the ECM. Metalloproteinase disorders can lead to cryptorchidism, azoospermia, poor semen quality and other diseases. As a member of the metalloproteinase family, ADAMTS plays an important role in testicular slippage to the scrotum. ADAM is involved in the fertilization process, and excessive MMP can damage the BTB. In the testis, metalloproteinase stability represents the stability of the extracellular microenvironment in which germ cells are located and is associated with reproductive function. Metalloproteinases have a definite relationship with male reproduction, but the underlying mechanism is still unclear. This paper summarizes the literature on various metalloproteinases in testicular tissue physiology and pathology to elucidate their role in reproductive function and male reproductive mechanisms.

Scd1 Deficiency in Early Embryos Affects Blastocyst ICM Formation through RPs-Mdm2-p53 Pathway.

Embryos contain a large number of lipid droplets, and lipid metabolism is gradually activated during embryonic development to provide energy. However, the regulatory mechanisms remain to be investigated. Stearoyl-CoA desaturase 1 (Scd1) is a fatty acid desaturase gene that is mainly involved in intracellular monounsaturated fatty acid production, which takes part in many physiological processes. Analysis of transcripts at key stages of embryo development revealed that Scd1 was important and expressed at an increased level during the cleavage and blastocyst stages. Knockout Scd1 gene by CRISPR/Cas9 from zygotes revealed a decrease in lipid droplets (LDs) and damage in the inner cell mass (ICM) formation of blastocyst. Comparative analysis of normal and knockout embryo transcripts showed a suppression of ribosome protein (RPs) genes, leading to the arrest of ribosome biogenesis at the 2-cell stage. Notably, the P53-related pathway was further activated at the blastocyst stage, which eventually caused embryonic development arrest and apoptosis. In summary, Scd1 helps in providing energy for embryonic development by regulating intra-embryonic lipid droplet formation. Moreover, deficiency activates the RPs-Mdm2-P53 pathway due to ribosomal stress and ultimately leads to embryonic development arrest. The present results suggested that Scd1 gene is essential to maintain healthy development of embryos by regulating energy support.

Ubiquitin C-terminal hydrolase L1 (UCHL1), a double-edged sword in mammalian oocyte maturation and spermatogenesis.

BACKGROUND: Recent studies have shown that ubiquitin-mediated cell apoptosis can modulate protein interaction and involve in the progress of oocyte maturation and spermatogenesis. As one of the key regulators involved in ubiquitin signal, ubiquitin C-terminal hydrolase L1 (UCHL1) is considered a molecular marker associated with spermatogonia stem cells. However, the function of UCHL1 was wildly reported to regulate various bioecological processes, such as Parkinson's disease, lung cancer, breast cancer and colon cancer, how UCHL1 affects the mammalian reproductive system remains an open question. METHODS: We identified papers through electronic searches of PubMed database from inception to July 2022. RESULTS: Here, we summarize the important function of UCHL1 in controlling mammalian oocyte development, regulating spermatogenesis and inhibiting polyspermy, and we posit the balance of UCHL1 was essential to maintaining reproductive cellular and tissue homeostasis. CONCLUSION: This study considers the 'double-edged sword' role of UCHL1 during gametogenesis and presents new insights into UCHL1 in germ cells.