NELL2-mediated lumicrine signaling through OVCH2 is required for male fertility

CRISPR/Cas9-mediated disruption of lipocalins, Ly6g5b, and Ly6g5c causes male subfertility in mice

BACKGROUND

Spermatozoa become mature and competent for fertilization during transit from the caput epididymis to the cauda epididymis. However, detailed molecular mechanisms of epididymal sperm maturation are still unclear. Here, we focused on multiple epididymis-enriched genes: lipocalin family genes (Lcn5, Lcn6, Lcn8, Lcn9, and Lcn10) and Ly6 family genes (Ly6g5b and Ly6g5c). These genes are evolutionarily conserved in mammals and form clusters on chromosomes 2 and 17 in the mouse, respectively.

OBJECTIVE

To clarify whether these genes are required for epididymal sperm maturation and acquisition of fertilizing ability, we generated knockout (KO) mice using the CRISPR/Cas9 system and analyzed their phenotype.

MATERIALS AND METHODS

We generated four lines of KO mice: Lcn9 single KO, the lipocalin family quadruple KO (Lcn5, Lcn6, Lcn8, and Lcn10), quintuple KO (Lcn5, Lcn6, Lcn8, Lcn10, and Lcn9), and double KO of Ly6 family genes (Ly6g5b and Ly6g5c).

RESULTS

Although the Lcn9 single KO did not affect male fertility, the quadruple KO and quintuple KO male mice were subfertile and mostly infertile, respectively, with a reduced amount of ADAM3, an essential protein for sperm binding to the zona pellucida. Further analysis revealed that the quintuple KO spermatozoa lack the CMTM2A/B that are required for ADAM3 maturation. Intriguingly, Ly6g5b and Ly6g5c double KO male mice also showed subfertility with reduced sperm ADAM3.

CONCLUSION

These results suggest epididymal secretory proteins are involved in ADAM3 maturation and acquisition of sperm fertilizing ability.

Loss of DIS3L in the initial segment is dispensable for sperm maturation in the epididymis and male fertility

DIS3L, a catalytic exoribonuclease associated with the cytoplasmic exosome complex, degrades cytoplasmic RNAs and is implicated in cancers and certain other diseases in humans. Epididymis plays a pivotal role in the transport, maturation, and storage of sperm required for male fertility. However, it remains unclear whether DIS3L-mediated cytoplasmic RNA degradation plays a role in epididymis biology and functioning. Herein, we fabricated a Dis3l conditional knockout (Dis3l cKO) mouse line in which DIS3L was ablated from the principal cells of the initial segment (IS). Morphological analyses showed that spermatogenesis and IS differentiation occurred normally in Dis3l cKO mice. Additionally, the absence of DIS3L had no dramatic influence on the transcriptome of IS. Moreover, the sperm count, morphology, motility, and acrosome reaction frequency in Dis3l cKO mice were comparable to that of the control, indicating that the Dis3l cKO males had normal fertility. Collectively, our genetic model demonstrates that DIS3L inactivation in the IS is nonessential for sperm maturation and male fertility.

Gene-deficient mouse model established by CRISPR/Cas9 system reveals 15 reproductive organ-enriched genes dispensable for male fertility

Since the advent of gene-targeting technology in embryonic stem cells, mice have become a primary model organism for investigating human gene function due to the striking genomic similarities between the two species. With the introduction of the CRISPR/Cas9 system for genome editing in mice, the pace of loss-of-function analysis has accelerated significantly. This has led to the identification of numerous genes that play crucial roles in male reproductive processes, including meiosis, chromatin condensation, flagellum formation in the testis, sperm maturation in the epididymis, and fertilization in the oviduct. Despite the advancements, the functions of many genes, particularly those enriched in male reproductive tissues, remain largely unknown. In our study, we focused on 15 genes and generated 13 gene-deficient mice [4933411K16Rik, Adam triple (Adam20, Adam25, and Adam39), BC048671, Cfap68, Gm4846, Gm4984, Gm13570, Nt5c1b, Ppp1r42, Saxo4, Sh3d21, Spz1, and Tektl1] to elucidate their roles in male fertility. Surprisingly, all 13 gene-deficient mice exhibited normal fertility in natural breeding experiments, indicating that these genes are not essential for male fertility. These findings have important implications as they may help prevent other research laboratories from duplicating efforts to generate knockout mice for genes that do not demonstrate an apparent phenotype related to male fertility. By shedding light on the dispensability of these genes, our study contributes to a more efficient allocation of research resources in the exploration of male reproductive biology.

Multiple genes in the Pate5-13 genomic region contribute to ADAM3 processing†

Sperm proteins undergo post-translational modifications during sperm transit through the epididymis to acquire fertilizing ability. We previously reported that the genomic region coding Pate family genes is key to the proteolytic processing of the sperm membrane protein ADAM3 and male fertility. This region contains nine Pate family genes (Pate5-13), and two protein-coding genes (Gm27235 and Gm5916), with a domain structure similar to Pate family genes. Therefore, in this study, we aimed to identify key factors by narrowing the genomic region. We generated three knockout (KO) mouse lines using CRISPR/Cas9: single KO mice of Pate10 expressed in the caput epididymis; deletion KO mice of six caput epididymis-enriched genes (Pate5-7, 13, Gm27235, and Gm5916) (Pate7-Gm5916 KO); and deletion KO mice of four genes expressed in the placenta and epididymis (Pate8, 9, 11, and 12) (Pate8-12 KO). We observed that the fertility of only Pate7-Gm5916 KO males was reduced, whereas the rest remained unaffected. Furthermore, when the caput epididymis-enriched genes, Pate8 and Pate10 remained in Pate7-Gm5916 KO mice were independently deleted, both KO males displayed more severe subfertility due to a decrease in mature ADAM3 and a defect in sperm migration to the oviduct. Thus, our data showed that multiple caput epididymis-enriched genes within the region coding Pate5-13 cooperatively function to ensure male fertility in mice.

Distinct actions of testicular endocrine and lumicrine signaling on the proximal epididymal transcriptome

The epididymal function and gene expression in mammals are under the control of the testis. Sex steroids are secreted from the testis and act on the epididymis in an endocrine manner. There is another, non-sex steroidal secreted signaling, named lumicrine signaling, in which testis-derived secreted proteins go through the male reproductive tract and act on the epididymis. The effects of such multiple regulations on the epididymis by the testis have been investigated for many genes. The recent development of high-throughput next-generation sequencing now enables us a further comparative survey of endocrine and lumicrine action-dependent gene expression. In the present study, testis-derived endocrine and lumicrine actions on epididymal gene expression were comparatively investigated by RNA-seq transcriptomic analyses. This investigation utilized experimental animal models in which testis-derived endocrine and/or lumicrine actions were interfered with, such as unilateral or bilateral orchidectomy. By bilateral orchidectomy, which interferes with both endocrine and lumicrine actions, 431 genes were downregulated. By unilateral orchidectomy, which also interferes with endocrine and lumicrine actions by the unilateral testis, but the endocrine action was compensated by the contralateral testis, 283 genes were downregulated. The content of such genes downregulated by unilateral orchidectomy was like those of lumicrine action-interfered efferent duct-ligation, W/Wv, and Nell2-/- mice. When genes affected by unilateral and bilateral orchidectomy were compared, 154 genes were commonly downregulated, whereas 217 genes were specifically downregulated only by bilateral orchidectomy, indicating the distinction between endocrine and lumicrine actions on the proximal epididymal transcriptome. Comparative transcriptome analyses also showed that the expressions of genes emerging since Amniota were notably impacted by bilateral orchidectomy, unilateral orchidectomy, and lumicrine action-interfering treatments; the degree of influence from these treatments varied based on the evolutionary stage beyond Amniota. These findings unveil an evolutional transition of regulated gene expression in the proximal epididymis by two different testis-derived signaling mechanisms.

Busulfan administration replicated the characteristics of the epididymal initial segment observed in mice lacking testis-epididymis lumicrine signaling

The physiological functions of the mammalian epididymis are typically regulated by the testes. In addition to sex steroids secreted by testicular Leydig cells, which act on the epididymis in an endocrine manner, there is a non-sex-steroidal signaling pathway known as the lumicrine pathway. This lumicrine signaling pathway involves ligand proteins secreted from germ cells within the testicular seminiferous tubules traversing the male reproductive tract, which induce epithelial differentiation in the epididymis. These findings prompted an inquiry into whether treatments influencing testis physiology can disrupt epididymal function by interfering with testis-epididymis communication. Busulfan, an alkylating agent commonly used to deplete testicular germ cells in reproductive biology, has not been sufficiently explored because of its effects on the epididymis. This study investigated the effects of busulfan administration on the proximal epididymis using histological and transcriptomic analyses. Notably, busulfan, as opposed to the vehicle dimethyl sulfoxide (DMSO), altered the morphology of the initial segment of the epididymis, leading to a reduction in the cell height of the luminal epithelium. RNA sequencing identified 185 significantly downregulated genes in the proximal epididymis of busulfan-administered mice compared to DMSO-administered mice. Comparative transcriptome analyses revealed similarities between the epididymal transcriptome of busulfan-administered mice and lumicrine-deficient mice, such as efferent-duct-ligated W/Wv and Nell2-/- mice. However, this differed from that of bilaterally orchidectomized mice, in which both the endocrine and lumicrine signaling pathways were simultaneously ablated. Collectively, these results suggested that the harmful effects of busulfan on the proximal epididymis are secondary consequences of the ablation of testis-epididymis lumicrine signaling.

Bringing proteomics to bear on male fertility: key lessons

INTRODUCTION

Male infertility is a major public health concern globally. Proteomics has revolutionized our comprehension of male fertility by identifying potential infertility biomarkers and reproductive defects. Studies comparing sperm proteome with other male reproductive tissues have the potential to refine fertility diagnostics and guide infertility treatment development.

AREAS COVERED

This review encapsulates literature using proteomic approaches to progress male reproductive biology. Our search methodology included systematic searches of databases such as PubMed, Scopus, and Web of Science for articles up to 2023. Keywords used included 'male fertility proteomics,' 'spermatozoa proteome,' 'testis proteomics,' 'epididymal proteomics,' and 'non-hormonal male contraception.' Inclusion criteria were robust experimental design, significant contributions to male fertility, and novel use of proteomic technologies.

EXPERT OPINION

Expert analysis shows a shift from traditional research to an integrative approach that clarifies male reproductive health's molecular intricacies. A gap exists between proteomic discoveries and clinical application. The expert opinions consolidated here not only navigate the current findings but also chart the future proteomic applications for scientific and clinical breakthroughs. We underscore the need for continued investment in proteomic research - both in the technological and collaborative arenas - to further unravel the secrets of male fertility, which will be central to resolving fertility issues in the coming era.

Taste receptor type 1 member 3 regulates Western diet-induced male infertility

Western diet (WD), characterized by a high intake of fats and sugary drinks, is a risk factor for male reproductive impairment. However, the molecular mechanisms underlying this remain unclear. Taste receptor type 1 member 3 (TAS1R3), activated by ligands of WD, is highly expressed in extra-oral tissues, particularly in the testes. Here, we investigated to determine the effects of WD intake on male reproduction and whether TAS1R3 mediates WD-induced impairment in male reproduction. Male C57BL/6 J wild-type (WT) and Tas1r3 knockout (KO) mice were fed either a normal diet and plain water (ND) or a 60 % high-fat-diet and 30 % (w/v) sucrose water (WD) for 18 weeks (n = 7-9/group). Long-term WD consumption significantly impaired sperm count, motility and testicular morphology in WT mice with marked Tas1r3 overexpression, whereas Tas1r3 KO mice were protected from WD-induced reproductive impairment. Testicular transcriptome analysis revealed downregulated AMP-activated protein kinase (AMPK) signaling and significantly elevated AMPK-targeted nuclear receptor 4A1 (Nr4a1) expression in WD-fed Tas1r3 KO mice. In vitro studies further validated that Tas1r3 knockdown in Leydig cells prevented the suppression of Nr4a1 and downstream steroidogenic genes (Star, Cyp11a1, Cyp17a1, and Hsd3b1) caused by high glucose, fructose, and palmitic acid levels, and maintained the levels of testosterone. Additionally, we analyzed the public human dataset to assess the clinical implications of our findings and confirmed a significant association between TAS1R3 and male-infertility-related diseases. Our findings suggest that TAS1R3 regulates WD-induced male reproductive impairment via the AMPK/NR4A1 signaling and can be a novel therapeutic target for male infertility.

CUB domains are not required for OVCH2 function in sperm maturation in the mouse epididymis

BACKGROUND

Ovochymase 2 (Ovch2) is an epididymis-specific gene that is required for male fertility. While a multitude of reproductive tract-specific genes required for male fertility have been identified, OVCH2 is thus far the first protein required for male fertility that contains Complement C1r/C1s, Uegf, Bmp1 (CUB) domains located in tandem in the C-terminus of the protein. Identifying the functional significance of this unique domain has implications in better understanding fertility and infertility and as a potential contraceptive target.

OBJECTIVE

The goals of these studies were to understand the influence and requirement of OVCH2 CUB domains in the localization and functional requirement of OVCH2 in sperm maturation and function.

MATERIALS AND METHODS

To this end, we performed in vivo localization analysis of OVCH2 and reproductive phenotype analysis of mice containing C-terminal FLAG tag on OVCH2, with either the entire protein intact, or CUB2 or both CUB1 and CUB2 genetically ablated. All mice were generated through the CRISPR/Cas9 gene editing approach.

RESULTS

We found that OVCH2 is specifically expressed in the proximal caput epididymidis, and the absence of CUB2 did not affect this localization pattern. Although the absence of both CUB domains significantly reduced sperm motility and progressive motility, this effect was not manifested in a reduction in fertility over a 6-month period mating trial, which showed no significant differences between control and CUB deletant mice. Further, the absence of one or both CUB domains did not affect reproductive organ structure or sperm morphology.

CONCLUSIONS

Our studies demonstrate that the CUB domains are not required for fertility in male mice, at least under the normal animal housing conditions our mice were tested in, and suggest that the enzymatic activity of the OVCH2 protease, in the absence of its CUB domains, is sufficient for normal sperm processing in the epididymis. Although our findings do not preclude the possibility that OVCH2 CUB domains are required under a yet-identified stress condition, our findings demonstrate that the most likely region for deleterious mutations in men with idiopathic infertility and the most vulnerable site for inhibition of OVCH2 protein function is in its protease domain, and not its CUB domains. Our findings have implications in the genetic screening of infertile men and the development of a novel non-hormonal male contraceptive by honing in on the more critical region of a functionally required protein.

Expression of NELL2/NICOL-ROS1 lumicrine signaling-related molecules in the human male reproductive tract

The maturation of spermatozoa is a regulated process, influenced by genes expressing essential secreted proteins in the proximal epididymis. Recent genetic studies in rodents have identified the non-sex steroidal molecular signals that regulate gene expression in the proximal epididymis. Germ cells in the testis secrete ligand proteins into the seminiferous tubule lumen The ligand proteins travel through the male reproductive tract lumen to the epididymis, where they bind to receptors, triggering the differentiation of the luminal epithelium for sperm maturation. It is, however, not fully unveiled if such a testis-epididymis trans-luminal signaling mechanism exists in other species, especially humans. In the present study, the rodent-type testis-epididymis trans-luminal signaling in the human male reproductive tract was evaluated in a step-by-step manner by analyzing testis and epididymis gene expression and signaling mediator protein function. There was a significant correlation between the epididymal expressions of mouse genes upregulated by the trans-luminal signaling and those of their human orthologs, as evaluated by the correlation coefficient of 0.604. The transcript expression of NELL2 and NICOL encoding putative ligand proteins was also observed in human testicular cells. In vitro experiments demonstrated that purified recombinant human NELL2 and NICOL formed a molecular complex with similar properties to rodent proteins, which was evaluated by a dissociation equilibrium constant of 110 nM. Recombinant human NELL2 also specifically bound to its putative receptor human ROS1 in vitro. Collectively, these findings suggest that the rodent-type testis-epididymis secreted signaling mechanism is also possible in the human male reproductive tract.

Individualized targeted treatment in a case of a rare TFG::ROS1 fusion positive inflammatory myofibroblastic tumor (IMT)

BACKGROUND

Inflammatory myofibroblastic tumor (IMTs) are rare mesenchymal neoplasms with slow growth. Resection is considered as therapeutic standard, with chemotherapy being insufficiently effective in advanced disease. ALK translocations are present in 50% of cases, ROS1 fusions (YWHAE::ROS1, TFG::ROS1) are extremely rare. Here, we present a case with TFG::ROS1 fusion and highlight the significance of molecular tumor boards (MTBs) in clinical precision oncology for post-last-line therapy.

CASE PRESENTATION

A 32-year-old woman presented with IMT diagnosed at age 27 for biopsy and treatment evaluation. Previous treatments included multiple resections and systemic therapy with vinblastine, cyclophosphamide, and methotrexate. A computed tomography scan showed extensive tumor infiltration of the psoas muscles and the posterior abdomen. Next generation sequencing revealed an actionable ROS1 fusion (TFG::ROS1) with breakpoints at exon 4/35 including the kinase domain and activating the RAS-pathway. TFG, the Trk-fused gene, exerts functions such as intracellular trafficking and exhibits high sequence homology between species. Based on single reports about efficacy of ROS1-targeting in ROS1 translocation positive IMTs the patient was started on crizotinib, an ATP-competitive small molecule c-MET, ALK and ROS1-inhibitor. With a follow-up of more than 9 months, the patient continues to show a profound response with major tumor regression, improved quality of life and no evidence for severe adverse events.

CONCLUSION

This case underscores the importance of the availability of modern molecular diagnostics and interdisciplinarity in precision oncology to identify rare, disease-defining genotypes that make an otherwise difficult-to-treat disease targetable.

KLC1-ROS1 Fusion Exerts Oncogenic Properties of Glioma Cells via Specific Activation of JAK-STAT Pathway

Here, we investigated the detailed molecular oncogenic mechanisms of a novel receptor tyrosine kinase (RTK) fusion, KLC1-ROS1, with an adapter molecule, KLC1, and an RTK, ROS1, discovered in pediatric glioma, and we explored a novel therapeutic target for glioma that possesses oncogenic RTK fusion. When wild-type ROS1 and KLC1-ROS1 fusions were stably expressed in the human glioma cell lines A172 and U343MG, immunoblotting revealed that KLC1-ROS1 fusion specifically activated the JAK2-STAT3 pathway, a major RTK downstream signaling pathway, when compared with wild-type ROS1. Immunoprecipitation of the fractionated cell lysates revealed a more abundant association of the KLC1-ROS1 fusion with JAK2 than that observed for wild-type ROS1 in the cytosolic fraction. A mutagenesis study of the KLC1-ROS1 fusion protein demonstrated the fundamental roles of both the KLC1 and ROS1 domains in the constitutive activation of KLC1-ROS1 fusion. Additionally, in vitro assays demonstrated that KLC1-ROS1 fusion upregulated cell proliferation, invasion, and chemoresistance when compared to wild-type ROS1. Combination treatment with the chemotherapeutic agent temozolomide and an inhibitor of ROS1, JAK2, or a downstream target of STAT3, demonstrated antitumor effects against KLC1-ROS1 fusion-expressing glioma cells. Our results demonstrate that KLC1-ROS1 fusion exerts oncogenic activity through serum-independent constitutive activation, resulting in specific activation of the JAK-STAT pathway. Our data suggested that molecules other than RTKs may serve as novel therapeutic targets for RTK fusion in gliomas.

CRISPR/Cas9-mediated genome editing reveals seven testis-enriched transmembrane glycoproteins dispensable for male fertility in mice

BACKGROUND

Mammalian fertilization is mediated by multiple sperm acrosomal proteins, many of which are testis-enriched transmembrane glycoproteins expressed during spermiogenesis (e.g., Izumo sperm-egg fusion 1, Sperm acrosome associated 6, and Transmembrane protein 95).

METHODS

We hypothesized that proteins with these features might have a role in sperm-egg interaction and thus carried out an in-silico screen based on multiple public databases. We generated knockout mouse lines lacking seven candidate proteins by the CRISPR/Cas9 system and conducted detailed analyses on the fecundity of the knockout males, as well as their testis appearance and weight, testis and epididymis histology, and sperm motility and morphology.

RESULTS

Through the in-silico screen, we identified 4932438H23Rik, A disintegrin and metalloproteinase domain-containing protein 29, SAYSvFN domain-containing protein 1, Sel-1 suppressor of lin-12-like 2 (C. elegans), Testis-expressed protein 2, Transmembrane and immunoglobulin domain-containing 3, and Zinc and ring finger 4. Phenotypic analyses unveiled that the knockout males showed normal testis gross appearance, normal testis and epididymis histology, and normal sperm morphology and motility. Fertility tests further indicated that the knockout male mice could sire pups with normal litter sizes when paired with wild-type females.

DISCUSSION AND CONCLUSION

These findings suggest that these seven proteins are individually dispensable for male reproduction and fertilization. Future studies are warranted to devise advanced in-silico screening approaches that permit effective identification of gamete fusion-required sperm proteins.

Segmental differentiation of the murine epididymis: identification of segment-specific, GM1-enriched vesicles and regulation by luminal fluid factors†

The murine epididymis has 10 distinct segments that provide the opportunity to identify compartmentalized cell physiological mechanisms underlying sperm maturation. However, despite the essential role of the epididymis in reproduction, remarkably little is known about segment-specific functions of this organ. Here, we investigate the dramatic segmental localization of the ganglioside GM1, a glycosphingolipid already known to play key roles in sperm capacitation and acrosome exocytosis. Frozen tissue sections of epididymides from adult mice were treated with the binding subunit of cholera toxin conjugated to AlexaFluor 488 to label GM1. We report that GM1-enriched vesicles were found exclusively in principal and clear cells of segment 2. These vesicles were also restricted to the lumen of segment 2 and did not appear to flow with the sperm into segment 3, within the limits of detection by confocal microscopy. Interestingly, this segment-specific presence was altered in several azoospermic mouse models and in wild-type mice after efferent duct ligation. These findings indicate that a lumicrine factor, itself dependent on spermatogenesis, controls this segmental differentiation. The RNA sequencing results confirmed global de-differentiation of the proximal epididymal segments in response to efferent duct ligation. Additionally, GM1 localization on the surface of the sperm head increased as sperm transit through segment 2 and have contact with the GM1-enriched vesicles. This is the first report of segment-specific vesicles and their role in enriching sperm with GM1, a glycosphingolipid known to be critical for sperm function, providing key insights into the segment-specific physiology and function of the epididymis.

Core binding factor subunit β plays diverse and essential roles in the male germline

Much of the foundation for lifelong spermatogenesis is established prior to puberty, and disruptions during this developmental window negatively impact fertility long into adulthood. However, the factors that coordinate prepubertal germline development are incompletely understood. Here, we report that core-binding factor subunit-β (CBFβ) plays critical roles in prepubertal development and the onset of spermatogenesis. Using a mouse conditional knockout (cKO) approach, inactivation of Cbfb in the male germline resulted in rapid degeneration of the germline during the onset of spermatogenesis, impaired overall sperm production, and adult infertility. Utilizing a different Cre driver to generate another Cbfb cKO model, we determined that the function of CBFβ in the male germline is likely limited to undifferentiated spermatogonia despite expression in other germ cell types. Within undifferentiated spermatogonia, CBFβ regulates proliferation, survival, and overall maintenance of the undifferentiated spermatogonia population. Paradoxically, we discovered that CBFβ also distally regulates meiotic progression and spermatid formation but only with Cbfb cKO within undifferentiated spermatogonia. Spatial transcriptomics revealed that CBFβ modulates cell cycle checkpoint control genes associated with both proliferation and meiosis. Taken together, our findings demonstrate that core programs established within the prepubertal undifferentiated spermatogonia population are necessary for both germline maintenance and sperm production.

Lumicrine signaling: Extracellular regulation of sperm maturation in the male reproductive tract lumen

The behaviors of cells, tissues, and organs are controlled by the extracellular environment in addition to their autonomous regulatory system. Dysfunction of extracellular regulatory mechanisms affects not only the development and survival of organisms but also successful reproduction. In this review article, a novel extracellular regulatory mechanism regulating the mammalian male reproductive ability will be briefly summarized. In terrestrial vertebrates, spermatozoa generated in the testis are transported through the lumen of the male reproductive tract and become functionally mature during the transport. Recent studies with gene-modified animals are unveiling the luminal extracellular environment of the reproductive tract to function not only as the pathway of sperm transport and the site of sperm maturation but also as the channel for cellular communication to regulate sperm maturation. Of special interest is the molecular mechanism of lumicrine signaling, a transluminal secreted signal transduction in the male reproductive tract lumen as a master regulator of sperm maturation and male reproductive ability. The general significance of such transluminal signaling in the context of cell biology will also be discussed.

Adhesion G protein-coupled receptor G2 is dispensable for lumicrine signaling regulating epididymal initial segment differentiation and gene expression†

The mammalian epididymis is the organ for functional sperm maturation. In rodents, the initial segment, the most proximal region of the epididymis, plays a critical role in sperm maturation. The luminal epithelial differentiation and the following gene expression of the initial segment are regulated by the lumicrine signaling, a testis-epididymis transluminal secreted signaling. Adhesion G protein-coupled receptor G2 (ADGRG2) is expressed in the efferent duct and the initial segment epididymis. In the preceding study, Adgrg2 ablation decreased the expression of several genes expressed in the initial segment. Such downregulated genes include those known to be regulated by lumicrine signaling, suggesting the involvement of ADGRG2 in lumicrine signaling. The present study examined whether ADGRG2 is associated with the lumicrine signaling regulating epididymal initial segment differentiation and gene expression. Adgrg2-null mice were generated by CRISPR/CAS9-mediated genome editing. The postnatal differentiation of the Adgrg2-null male epididymal initial segment was histologically comparable with that of control wild-type animals. The RNA-seq of Adgrg2-null mice was performed together with those of efferent duct-ligated and W/Wv mice in both of which lumicrine signaling is defective. The comparative transcriptome analyses clarified that the expressions of genes expressed in the initial segment and regulated by lumicrine signaling were decreased by Adgrg2 nullification. However, the extent of such downregulations observed in Adgrg2-null epididymis was not so prominent compared with those of lumicrine signaling deficient Nell2-/-, efferent duct-ligated, or W/Wv mice. Collectively, these findings indicate that ADGRG2 is dispensable for the lumicrine regulation of epididymal initial segment differentiation.

Epithelial and mesenchymal fate decisions in Wolffian duct development

Wolffian ducts (WDs) are the paired embryonic structures that give rise to internal male reproductive tract organs. WDs are initially formed in both sexes but have sex-specific fates during sexual differentiation. Understanding WD differentiation requires insights into the process of fate decisions of epithelial and mesenchymal cells, which are tightly coordinated by endocrine, paracrine, and autocrine signals. In this review, we discuss current advances in understanding the fate-decision process of WD epithelial and mesenchymal lineages from their initial formation at the embryonic stage to postnatal differentiation. Finally, we discuss aberrant cell differentiation in WD abnormalities and pathologies and identify opportunities for future investigations.

Melatonin alleviated fluoride-induced impairment of spermatogenesis and sperm maturation process via Interleukin-17A

Fluoride-induced male reproductive failure is a major environmental and human health concern, but interventions are still lacking. Melatonin (MLT) has potential functions in regulating testicular damage and interleukin-17 (IL-17) production. This study aims to explore whether MLT can mitigate fluoride-induced male reproductive toxicity through IL-17A, and screen the potential targets. So the wild type and IL-17A knockout mice were employed and treated with sodium fluoride (100 mg/L) by drinking water and MLT (10 mg/kg.BW, intraperitoneal injection per two days starting from week 16) for 18 weeks. Bone F- concentrations, grade of dental damage, sperm quality, spermatogenic cells counts, histological morphology of testis and epididymis, and the mRNA expression of spermatogenesis and maturation, classical pyroptosis related and immune factor genes were detected respectively. The results revealed that MLT supplementations alleviated fluoride-induced impairment of spermatogenesis and maturation process, protecting the morphology of testis and epididymis through IL-17A pathway, and Tesk1 and Pten were identified as candidate targets from 29 regulation genes. Taken together, this study demonstrated a new physiological role for MLT in the protection against fluoride-induced reproductive injury and possible regulation mechanisms, which providing a useful therapeutic strategy for male reproductive function failure caused by fluoride or other environmental pollutants.

Transcriptome profiling of the initial segment and proximal caput of mouse epididymis

Background

The proximal region of the mouse epididymis plays a pivotal role in sperm transport, sperm maturation, and male fertility. Several studies have focused on segment-dependent gene expression of the mouse epididymis through high-throughput sequencing without the precision of the microdissection.

Methods and results

Herein, we isolated the initial segment (IS) and proximal caput (P-caput) by physical microdissection using an Lcn9-cre; Rosa26tdTomato mouse model. We defined the transcriptome changes of caput epididymis by RNA sequencing (RNA-seq), which identified 1,961 genes that were abundantly expressed in the IS and 1,739 genes that were prominently expressed in the P-caput. In addition, we found that many differentially expressed genes (DEGs) were predominantly or uniquely expressed in the epididymis and region-specific genes were highly associated with transport, secretion, sperm motility, fertilization, and male fertility.

Conclusion

Thus, this study provides an RNA-seq resource to identify region-specific genes in the caput epididymis. The epididymal-selective/specific genes are potential targets for male contraception and may provide new insights into understanding segment-specific epididymal microenvironment-mediated sperm transport, maturation, and male fertility.

Single-cell RNA sequencing reveals the local cell landscape in mouse epididymal initial segment during aging

BACKGROUND

Morphological and functional alterations in aging reproductive organs result in decreased male fertility. The epididymis functions as the transition region for post-testicular sperm maturation. And we have previously demonstrated that the epididymal initial segment (IS), a region of the reproductive tract essential for sperm maturation and capacitation, undergoes considerable histological changes and chronic immune activation in mice during aging. However, the local aging-associated cellular and molecular changes in the aged epididymal IS are poorly understood.

RESULTS

We conducted single-cell RNA sequencing analysis on the epididymal IS of young (3-month-old) and old (21-month-old) mice. In total, 10,027 cells from the epididymal IS tissues of young and old mice were obtained and annotated. The cell composition, including the expansion of a principal cell subtype and Ms4a4b^HiMs4a6b^Hi T cells, changed with age. Aged principal cells displayed multiple functional gene expression changes associated with acrosome reaction and sperm maturation, suggesting an asynchronous process of sperm activation and maturation during epididymal transit. Meanwhile, aging-related altered pathways in immune cells, especially the "cell chemotaxis" in Cx3cr1^Hi epididymal dendritic cells (eDCs), were identified. The monocyte-specific expression of chemokine Ccl8 increased with age in eDCs. And the aged epididymal IS showed increased inflammatory cell infiltration and cytokine secretion. Furthermore, cell-cell communication analysis indicated that age increased inflammatory signaling in the epididymal IS.

CONCLUSION

Contrary to the general pattern of lower immune responses in the male proximal genital tract, we revealed an inflammaging status in mouse epididymal initial segment. These findings will allow future studies to enable the delay of male reproductive aging via immune regulation.

Epididymal DIS3 exosome ribonuclease is not necessary for mouse sperm maturation or fertility

DIS3 is an RNA exosome associated ribonuclease that degrades a wide range of transcripts that can be essential for cell survival and development. The proximal region of the mouse epididymis (initial segment and caput) plays a pivotal role in sperm transport and maturation required for male fertility. However, whether DIS3 ribonuclease mediates RNA decay in proximal epididymides remains unclear. Herein, we established a conditional knockout mouse line by crossing a floxed Dis3 allele with Lcn9-cre mice in which the recombinase is expressed in the principal cells of initial segment as early as post-natal day 17. Morphological and histological analyses, immunofluorescence, computer-aided sperm analysis and fertility were used for functional analyses. We document that DIS3 deficiency in the initial segment had no effect on male fertility. Dis3 cKO males had normal spermatogenesis and initial segment development. In cauda epididymides of Dis3 cKO mice, sperm abundance, morphology, motility, and the frequency of acrosome exocytosis were comparable to controls. Collectively, our genetic model demonstrates that loss of DIS3 in the initial segment of the epididymis is not essential for sperm maturation, motility, or male fertility.

A small secreted protein NICOL regulates lumicrine-mediated sperm maturation and male fertility

The mammalian spermatozoa produced in the testis require functional maturation in the epididymis for their full competence. Epididymal sperm maturation is regulated by lumicrine signalling pathways in which testis-derived secreted signals relocate to the epididymis lumen and promote functional differentiation. However, the detailed mechanisms of lumicrine regulation are unclear. Herein, we demonstrate that a small secreted protein, NELL2-interacting cofactor for lumicrine signalling (NICOL), plays a crucial role in lumicrine signalling in mice. NICOL is expressed in male reproductive organs, including the testis, and forms a complex with the testis-secreted protein NELL2, which is transported transluminally from the testis to the epididymis. Males lacking Nicol are sterile due to impaired NELL2-mediated lumicrine signalling, leading to defective epididymal differentiation and deficient sperm maturation but can be restored by NICOL expression in testicular germ cells. Our results demonstrate how lumicrine signalling regulates epididymal function for successful sperm maturation and male fertility.

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.

Vasopressin V1a receptor and oxytocin receptor regulate murine sperm motility differently

Specific receptors for the neurohypophyseal hormones, arginine vasopressin (AVP) and oxytocin, are present in the male reproductive organs. However, their exact roles remain unknown. To elucidate the physiological functions of pituitary hormones in male reproduction, this study first focused on the distribution and function of one of the AVP receptors, V1a. In situ hybridization analysis revealed high expression of the Avpr1a in Leydig cells of the testes and narrow/clear cells in the epididymis, with the expression pattern differing from that of the oxytocin receptor (OTR). Notably, persistent motility and highly proportional hyperactivation were observed in spermatozoa from V1a receptor-deficient mice. In contrast, OTR blocking by antagonist atosiban decreased hyperactivation rate. Furthermore, AVP stimulation could alter the extracellular pH mediated by the V1a receptor. The results highlight the crucial role of neurohypophyseal hormones in male reproductive physiology, with potential contradicting roles of V1a and OTR in sperm maturation. Our findings suggest that V1a receptor antagonists are potential therapeutic drugs for male infertility.

Deficiency of primate-specific SSX1 induced asthenoteratozoospermia in infertile men and cynomolgus monkey and tree shrew models

Primate-specific genes (PSGs) tend to be expressed in the brain and testis. This phenomenon is consistent with brain evolution in primates but is seemingly contradictory to the similarity of spermatogenesis among mammals. Here, using whole-exome sequencing, we identified deleterious variants of X-linked SSX1 in six unrelated men with asthenoteratozoospermia. SSX1 is a PSG expressed predominantly in the testis, and the SSX family evolutionarily expanded independently in rodents and primates. As the mouse model could not be used for studying SSX1, we used a non-human primate model and tree shrews, which are phylogenetically similar to primates, to knock down (KD) Ssx1 expression in the testes. Consistent with the phenotype observed in humans, both Ssx1-KD models exhibited a reduced sperm motility and abnormal sperm morphology. Further, RNA sequencing indicated that Ssx1 deficiency influenced multiple biological processes during spermatogenesis. Collectively, our experimental observations in humans and cynomolgus monkey and tree shrew models highlight the crucial role of SSX1 in spermatogenesis. Notably, three of the five couples who underwent intra-cytoplasmic sperm injection treatment achieved a successful pregnancy. This study provides important guidance for genetic counseling and clinical diagnosis and, significantly, describes the approaches for elucidating the functions of testis-enriched PSGs in spermatogenesis.

Reconstitution of reproductive organ system that produces functional oocytes

Reproductive organs have unique developmental and functional properties that enable them to manage both germ cell development and the endocrine system in a sex-dependent manner. Proper reconstitution of the reproductive organs, therefore, will contribute to a deeper understanding of the mechanisms underlying germ cell development and sex-determination. However, reproductive organs have not yet been systematically reconstituted from pluripotent stem cells. This is largely due to technical problems in the reconstitution of the germ cell and somatic cell lineages, which have very different developmental trajectories. Accordingly, faithful construction of reproductive organoids requires that the reconstitution and evaluation of these two different cell lineages be performed separately. Here, we update the state-of-the-art in the reconstitution of reproductive organoids that produce functional oocytes.

ADK-VR2, a cell line derived from a treatment-naïve patient with SDC4-ROS1 fusion-positive primarily crizotinib-resistant NSCLC: a novel preclinical model for new drug development of ROS1-rearranged NSCLC

BACKGROUND

ROS1 fusions are driver molecular alterations in 1-2% of non-small cell lung cancers (NSCLCs). Several tyrosine kinase inhibitors (TKIs) have shown high efficacy in patients whose tumors harbour a ROS1 fusion. However, the limited availability of preclinical models of ROS1-positive NSCLC hinders the discovery of new drugs and the understanding of the mechanisms underlying drug resistance and strategies to overcome it.

METHODS

The ADK-VR2 cell line was derived from the pleural effusion of a treatment-naïve NSCLC patient bearing SDC4-ROS1 gene fusion. The sensitivity of ADK-VR2 and its crizotinib-resistant clone ADK-VR2 AG143 (selected in 3D culture in the presence of crizotinib) to different TKIs was tested in vitro, in both 2D and 3D conditions. Tumorigenic and metastatic ability was assessed in highly immunodeficient mice. In addition, crizotinib efficacy on ADK-VR2 was evaluated in vivo.

RESULTS

2D-growth of ADK-VR2 cells was partially inhibited by crizotinib. On the contrary, the treatment with other TKIs, such as lorlatinib, entrectinib and DS-6051b, did not result in cell growth inhibition. TKIs showed dramatically different efficacy on ADK-VR2 cells, depending on the cell culture conditions. In 3D culture, ADK-VR2 growth was indeed almost totally inhibited by lorlatinib and DS-6051b. The clone ADK-VR2 AG143 showed higher resistance to crizotinib treatment in vitro, compared to its parental cell line, in both 2D and 3D cultures. Similarly to ADK-VR2, ADK-VR2 AG143 growth was strongly inhibited by lorlatinib in 3D conditions. Nevertheless, ADK-VR2 AG143 sphere formation was less affected by TKIs treatment, compared to the parental cell line. In vivo experiments highlighted the high tumorigenic and metastatic ability of ADK-VR2 cell line, which, once injected in immunodeficient mice, gave rise to both spontaneous and experimental lung metastases while the crizotinib-resistant clone ADK-VR2 AG143 showed a slower growth in vivo. In addition, ADK-VR2 tumor growth was significantly reduced but not eradicated by crizotinib treatment.

CONCLUSIONS

The ADK-VR2 cell line is a promising NSCLC preclinical model for the study of novel targeted therapies against ROS1 fusions and the mechanisms of resistance to TKI therapies.

Tissue hydraulics in reproduction

The development of functional eggs and sperm are critical processes in mammalian development as they ensure successful reproduction and species propagation. While past studies have identified important genes that regulate these processes, the roles of luminal flow and fluid stress in reproductive biology remain less well understood. Here, we discuss recent evidence that support the diverse functions of luminal fluid in oogenesis, spermatogenesis and embryogenesis. We also review emerging techniques that allow for precise quantification and perturbation of tissue hydraulics in female and male reproductive systems, and propose new questions and approaches in this field. We hope this review will provide a useful resource to inspire future research in tissue hydraulics in reproductive biology and diseases.

The molecular mechanisms of mammalian sperm maturation regulated by NELL2-ROS1 lumicrine signaling

In terrestrial vertebrates, spermatozoa generated in the testis are transported through the reproductive tract toward outside the body. In addition to as the pathway of sperm transport, the male reproductive tract also functions as the site of post-testicular sperm maturation and the epididymis, which constitutes the majority of male reproductive tract, plays central roles in such a sperm maturation. Recent studies with gene-modified animals have been unveiling not only the molecular mechanisms of sperm maturation in the epididymis but the regulatory system by which the epididymis acquires and executes sperm maturing functions. In this review, the mechanisms of mammalian sperm maturation will be summarized, based on recent findings including the lumicrine regulation of sperm maturation.

Transcriptional Regulatory Role of NELL2 in Preproenkephalin Gene Expression

Preproenkephalin (PPE) is a precursor molecule for multiple endogenous opioid peptides Leu-enkephalin (ENK) and Met-ENK, which are involved in a wide variety of modulatory functions in the nervous system. Despite the functional importance of ENK in the brain, the effect of brain-derived factor(s) on PPE expression is unknown. We report the dual effect of neural epidermal growth factor (EGF)-likelike 2 (NELL2) on PPE gene expression. In cultured NIH3T3 cells, transfection of NELL2 expression vectors induced an inhibition of PPE transcription intracellularly, in parallel with downregulation of protein kinase C signaling pathways and extracellular signal-regulated kinase. Interestingly, these phenomena were reversed when synthetic NELL2 was administered extracellularly. The in vivo disruption of NELL2 synthesis resulted in an increase in PPE mRNA level in the rat brain, suggesting that the inhibitory action of intracellular NELL2 predominates the activation effect of extracellular NELL2 on PPE gene expression in the brain. Biochemical and molecular studies with mutant NELL2 structures further demonstrated the critical role of EGF-like repeat domains in NELL2 for regulation of PPE transcription. These are the first results to reveal the spatio-specific role of NELL2 in the homeostatic regulation of PPE gene expression.

Current treatments for non-small cell lung cancer

Despite improved methods of diagnosis and the development of different treatments, mortality from lung cancer remains surprisingly high. Non-small cell lung cancer (NSCLC) accounts for the large majority of lung cancer cases. Therefore, it is important to review current methods of diagnosis and treatments of NSCLC in the clinic and preclinic. In this review, we describe, as a guide for clinicians, current diagnostic methods and therapies (such as chemotherapy, chemoradiotherapy, targeted therapy, antiangiogenic therapy, immunotherapy, and combination therapy) for NSCLC.

An integrative approach to uncover the components, mechanisms, and functions of traditional Chinese medicine prescriptions on male infertility

Male infertility is a major and growing health problem with an estimated global prevalence of 4.2%. The current therapy is limited by the unknown etiology of MI, emphasizing the critical requirement forward to a more efficient method or medication. Through thousands of years, Traditional Chinese Medicine (TCM) has been shown to be effective in treating MI effectively. However, the components, mechanisms and functions of TCM prescriptions on MI are still obscure, severely limiting its clinical application. In order to discover the molecular mechanism of TCM against MI, our study presents a comprehensive approach integrated data mining, network pharmacology, molecular docking, UHPLC-Q-Orbitrap HRMS, and experimental validation. Here, we begin to acquire 289 clinical TCM prescriptions for MI from a TCM hospital’s outpatient department. Then, Core Chinese Materia Medica (CCMM) was then retrieved from the TCM Inheritance Support System (TCMISS), which was utilized to discover the underlying rules and connections in clinical prescriptions. After that, 98 CCMM components and 816 MI targets were obtained from ten distinct databases. Additionally, the network pharmacology methods, including network construction, GO and KEGG pathway enrichment, PPI analysis, were utilized to reveal that kaempferol, quercetin, isorhamnetin, and beta-sitosterol are the core components of CCMM in treating MI. The mechanisms and functions of CCMM against MI are hormone regulation, anti-apoptosis, anti-oxidant stress, and anti-inflammatory. Furthermore, the strong connections between four core components and six key targets were verified using a molecular docking method. Following that, the core components of the CCMM extract were identified using UHPLC-Q-Orbitrap HRMS analysis. Finally, in vivo experiments demonstrated that CCMM and four core components could improve the density, motility, viability of sperm, lecithin corpuscle density, decrease the rate of sperm malformation and testis tissue damage, and regulate the protein expressions of AKT1, MAPK3/1, EGFR, and TNF-α in a mouse model of MI. UHPLC-Q-Orbitrap HRMS analysis and in vivo experiments further validated the results of data mining, network pharmacology, and molecular docking. Our study could uncover the components, mechanisms, and functions of TCM prescriptions against MI and develop a new integrative approach to demonstrate TCM’s multi-component, multi-target, and multi-pathway approach to disease treatment.

Identifying pleiotropic variants and candidate genes for fertility and reproduction traits in Holstein cattle via association studies based on imputed whole-genome sequence genotypes

Background

Genetic progress for fertility and reproduction traits in dairy cattle has been limited due to the low heritability of most indicator traits. Moreover, most of the quantitative trait loci (QTL) and candidate genes associated with these traits remain unknown. In this study, we used 5.6 million imputed DNA sequence variants (single nucleotide polymorphisms, SNPs) for genome-wide association studies (GWAS) of 18 fertility and reproduction traits in Holstein cattle. Aiming to identify pleiotropic variants and increase detection power, multiple-trait analyses were performed using a method to efficiently combine the estimated SNP effects of single-trait GWAS based on a chi-square statistic.

Results

There were 87, 72, and 84 significant SNPs identified for heifer, cow, and sire traits, respectively, which showed a wide and distinct distribution across the genome, suggesting that they have relatively distinct polygenic nature. The biological functions of immune response and fatty acid metabolism were significantly enriched for the 184 and 124 positional candidate genes identified for heifer and cow traits, respectively. No known biological function was significantly enriched for the 147 positional candidate genes found for sire traits. The most important chromosomes that had three or more significant QTL identified are BTA22 and BTA23 for heifer traits, BTA8 and BTA17 for cow traits, and BTA4, BTA7, BTA17, BTA22, BTA25, and BTA28 for sire traits. Several novel and biologically important positional candidate genes were strongly suggested for heifer (SOD2, WTAP, DLEC1, PFKFB4, TRIM27, HECW1, DNAH17, and ADAM3A), cow (ANXA1, PCSK5, SPESP1, and JMJD1C), and sire (ELMO1, CFAP70, SOX30, DGCR8, SEPTIN14, PAPOLB, JMJD1C, and NELL2) traits.

Conclusions

These findings contribute to better understand the underlying biological mechanisms of fertility and reproduction traits measured in heifers, cows, and sires, which may contribute to improve genomic evaluation for these traits in dairy cattle.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08555-z.

Spatiotemporal Small Non-coding RNAs Expressed in the Germline as an Early Biomarker of Testicular Toxicity and Transgenerational Effects Caused by Prenatal Exposure to Nanosized Particles

In recent years, an apparent decline in human sperm quality has been observed worldwide. One in every 5.5 couples suffers from infertility, with male reproductive problems contributing to nearly 40% of all infertility cases. Although the reasons for the increasing number of infertility cases are largely unknown, both genetic and environmental factors can be contributing factors. In particular, exposure to chemical substances during mammalian male germ cell development has been linked to an increased risk of infertility in later life owing to defective sperm production, reproductive tract obstruction, inflammation, and sexual disorders. Prenatal exposure to nanomaterials (NMs) is no exception. In animal experiments, maternal exposure to NMs has been reported to affect the reproductive health of male offspring. Male germ cells require multiple epigenetic reprogramming events during their lifespan to acquire reproductive capacity. Given that spermatozoa deliver the paternal genome to oocytes upon fertilization, we hypothesized that maternal exposure to NMs negatively affects male germ cells by altering epigenetic regulation, which may in turn affect embryo development. Small non-coding RNAs (including microRNAs, PIWI-interacting RNAs, tRNA-derived small RNAs, and rRNA-derived small RNAs), which are differentially expressed in mammalian male germ cells in a spatiotemporal manner, could play important regulatory roles in spermatogenesis and embryogenesis. Thus, the evaluation of RNAs responsible for sperm fertility is of great interest in reproductive toxicology and medicine. However, whether the effect of maternal exposure to NMs on spermatogenesis in the offspring (intergenerational effects) really triggers multigenerational effects remains unclear, and infertility biomarkers for evaluating paternal inheritance have not been identified to date. In this review, existing lines of evidence on the effects of prenatal exposure to NMs on male reproduction are summarized. A working hypothesis of the transgenerational effects of sperm-derived epigenomic changes in the F1 generation is presented, in that such maternal exposure could affect early embryonic development followed by deficits in neurodevelopment and male reproduction in the F2 generation.

Anatomical Transcriptome Atlas of the Male Mouse Reproductive System During Aging

The elderly males undergo degenerative fertility and testicular endocrine function that jeopardize the reproductive health and well-being. However, the mechanisms underlying reproductive aging are unclear. Here, we tried to address this by investigating the phenotypes and transcriptomes of seven regions of the male mouse reproductive tract: the testis, efferent ductules, initial segment, caput, corpus and cauda epididymidis, and vas deferens, in adult (3 months) and aged (21 months) mice. Quantitative PCR, immunohistochemistry, immunofluorescent staining, and enzyme-linked immunosorbent assay were performed for the analysis of gene expression in mice, human tissues, and semen samples. Aged male mice showed both systematic and reproductive changes, and remarkable histological changes were detected in the testis and proximal epididymis. Transcriptomes of the male reproductive tract were mapped, and a series of region-specific genes were identified and validated in mouse and/or human tissues, including Protamine 1 (Prm2), ADAM metallopeptidase domain 28 (Adam28), Ribonuclease A family member 13 (Rnase13), WAP four-disulfide core domain 13 (Wfdc13), and Wfdc9. Meanwhile, age-related transcriptome changes of different regions of the male reproductive tract were characterized. Notably, increased immune response was functionally related to the male reproductive aging, especially the T cell activation. An immune response-associated factor, phospholipase A2 group IID (Pla2g2d), was identified as a potential biomarker for reproductive aging in mice. And the PLA2G2D level in human seminal plasma surged at approximately 35 years of age. Furthermore, we highlighted Protein tyrosine phosphatase receptor type C (Ptprc), Lymphocyte protein tyrosine kinase (Lck), Microtubule associated protein tau (Mapt), and Interferon induced protein with tetratricopeptide repeats 3 (Ifit3) as critical molecules in the aging of initial segment, caput, caput, and cauda epididymidis, respectively. This study provides an RNA-seq resource for the male reproductive system during aging in mice, and is expected to improve our understanding of male reproductive aging and infertility.

Calcium Homeostasis in the Epididymal Microenvironment: Is Extracellular Calcium a Cofactor for Matrix Gla Protein-Dependent Scavenging Regulated by Vitamins

In the male reproductive tract, the epididymis is an essential organ for sperm maturation, in which sperm cells acquire mobility and the ability to fertilize oocytes while being stored in a protective microenvironment. Epididymal function involves a specialized luminal microenvironment established by the epithelial cells of epididymal mucosa. Low-calcium concentration is a unique feature of this epididymal luminal microenvironment, its relevance and regulation are, however, incompletely understood. In the rat epididymis, the vitamin D-related calcium-dependent TRPV6-TMEM16A channel-coupler has been shown to be involved in fluid transport, and, in a spatially complementary manner, vitamin K2-related γ-glutamyl carboxylase (GGCX)-dependent carboxylation of matrix Gla protein (MGP) plays an essential role in promoting calcium-dependent protein aggregation. An SNP in the human GGCX gene has been associated with asthenozoospermia. In addition, bioinformatic analysis also suggests the involvement of a vitamin B6-axis in calcium-dependent MGP-mediated protein aggregation. These findings suggest that vitamins interact with calcium homeostasis in the epididymis to ensure proper sperm maturation and male fertility. This review article discusses the regulation mechanisms of calcium homeostasis in the epididymis, and the potential role of vitamin interactions on epididymal calcium homeostasis, especially the role of matrix calcium in the epididymal lumen as a cofactor for the carboxylated MGP-mediated scavenging function.

H3K27ac chromatin acetylation and gene expression analysis reveal sex- and situs-related differences in developing chicken gonads

BACKGROUND

Birds exhibit a unique asymmetry in terms of gonad development. The female left gonad generates a functional ovary, whereas the right gonad regresses. In males, both left and right gonads would develop into testes. How is this left/right asymmetry established only in females but not in males remains unknown. The epigenetic regulation of gonadal developmental genes may contribute to this sex disparity. The modification of histone tails such as H3K27ac is tightly coupled to chromatin activation and gene expression. To explore whether H3K27ac marked chromatin activation is involved in the asymmetric development of avian gonads, we probed genome-wide H3K27ac occupancy in left and right gonads from both sexes and related chromatin activity profile to the expression of gonadal genes. Furthermore, we validated the effect of chromatin activity on asymmetric gonadal development by manipulating the chromatin histone acetylation levels.

METHODS

The undifferentiated gonads from both sides of each sex were collected and subjected to RNA-Seq and H3K27ac ChIP-Seq experiments. Integrated analysis of gene expression and active chromatin regions were performed to identify the sex- and situs-specific regulation and expression of gonadal genes. The histone deacetylase inhibitor trichostatin A (TSA) was applied to the undifferentiated female right gonads to assess the effect of chromatin activation on gonadal gene expression and cell proliferation.

RESULTS

Even before sex differentiation, the gonads already show divergent gene expression between different sexes and between left/right sides in females. The sex-specific H3K27ac chromatin distributions coincide with the higher expression of male/female specification genes in each sex. Unexpectedly, the H3K27ac marked chromatin activation show a dramatic difference between left and right gonads in both sexes, although the left/right asymmetric gonadal development was observed only in females but not in males. In females, the side-specific H3K27ac occupancy instructs the differential expression of developmental genes between the pair of gonads and contributes to the development of left but not right gonad. However, in males, the left/right discrepancy of H3K27ac chromatin distribution does not drive the side-biased gene expression or gonad development. The TSA-induced retention of chromatin acetylation causes up-regulation of ovarian developmental genes and increases cell proliferation in the female right gonad.

CONCLUSIONS

We revealed that left/right asymmetry in H3K27ac marked chromatin activation exists in both sexes, but this discrepancy gives rise to asymmetric gonadal development only in females. Other mechanisms overriding the chromatin activation would control the symmetric development of male gonads in chicken.

Proteolysis in Reproduction: Lessons From Gene-Modified Organism Studies

The physiological roles of proteolysis are not limited to degrading unnecessary proteins. Proteolysis plays pivotal roles in various biological processes through cleaving peptide bonds to activate and inactivate proteins including enzymes, transcription factors, and receptors. As a wide range of cellular processes is regulated by proteolysis, abnormalities or dysregulation of such proteolytic processes therefore often cause diseases. Recent genetic studies have clarified the inclusion of proteases and protease inhibitors in various reproductive processes such as development of gonads, generation and activation of gametes, and physical interaction between gametes in various species including yeast, animals, and plants. Such studies not only clarify proteolysis-related factors but the biological processes regulated by proteolysis for successful reproduction. Here the physiological roles of proteases and proteolysis in reproduction will be reviewed based on findings using gene-modified organisms.

Deepening the Knowledge of ROS1 Rearrangements in Non-Small Cell Lung Cancer: Diagnosis, Treatment, Resistance and Concomitant Alterations

ROS proto-oncogene 1 (ROS1) rearrangements are reported in about 1-2% of non-squamous non-small-cell lung cancer (NSCLC). After efficacy of crizotinib was demonstrated, identification of ROS1 translocations in advanced disease became fundamental to give patients the chance of specific and effective treatment. Different methods are available for detection of rearrangements, and probably the real prevalence of ROS1 rearrangements is higher than that reported in literature, as our capacity to detect gene rearrangements is improving. In particular, with next generation sequencing (NGS) techniques, we are currently able to assess multiple genes simultaneously with increasing sensitivity. This is leading to overcome the "single oncogenic driver" paradigm, and in the very near future, the co-existence of multiple drivers will probably emerge more frequently and represent a therapeutic issue. Since recently, crizotinib has been the only available therapy, but today, many other tyrosine kinase inhibitors (TKI) are emerging and seem promising both in first and subsequent lines of treatment. Indeed, novel inhibitors are also able to overcome resistance mutations to crizotinib, hypothesizing a possible sequential strategy also in ROS1-rearranged disease. In this review, we will focus on ROS1 rearrangements, dealing with diagnostic aspects, new therapeutic options, resistance issues and the coexistence of ROS1 translocations with other molecular alterations.

The conserved fertility factor SPACA4/Bouncer has divergent modes of action in vertebrate fertilization

Fertilization is the fundamental process that initiates the development of a new individual in all sexually reproducing species. Despite its importance, our understanding of the molecular players that govern mammalian sperm-egg interaction is incomplete, partly because many of the essential factors found in nonmammalian species do not have obvious mammalian homologs. We have recently identified the lymphocyte antigen-6 (Ly6)/urokinase-type plasminogen activator receptor (uPAR) protein Bouncer as an essential fertilization factor in zebrafish [S. Herberg, K. R. Gert, A. Schleiffer, A. Pauli, Science 361, 1029-1033 (2018)]. Here, we show that Bouncer's homolog in mammals, Sperm Acrosome Associated 4 (SPACA4), is also required for efficient fertilization in mice. In contrast to fish, in which Bouncer is expressed specifically in the egg, SPACA4 is expressed exclusively in the sperm. Male knockout mice are severely subfertile, and sperm lacking SPACA4 fail to fertilize wild-type eggs in vitro. Interestingly, removal of the zona pellucida rescues the fertilization defect of Spaca4-deficient sperm in vitro, indicating that SPACA4 is not required for the interaction of sperm and the oolemma but rather of sperm and the zona pellucida. Our work identifies SPACA4 as an important sperm protein necessary for zona pellucida penetration during mammalian fertilization.

Tackling Refractory Metastatic Colorectal Cancer: Future Perspectives

Substantial improvements have characterized the systemic treatment of metastatic colorectal cancer (mCRC) over the past 20 years. Besides strong evidence that supports the use of RAS and BRAF status as prognostic and predictive indicators of disease and response, novel technologies have made possible the incorporation of emerging biomarkers for the management of mCRC. On one hand, the discovery of point mutations, amplifications, fusions, and gene expression profiles highlights the genomic and dynamic complexity of CRC. On the other, such discoveries are leading to newer biomarker-driven strategies that add to existing anti-epidermal growth factor receptor (EGFR) and anti-angiogenic approaches. In addition, the availability of a wide molecular profiling has relevant implications for patient prognosis and treatment benefits. Here, we will review the molecular underpinnings and clinical data supporting novel targeted treatments under development for refractory mCRC harboring BRAF mutations, KRAS G12C mutations, HER2 amplification, and less common molecular alterations, such as the re-arrangements of NTRK, ALK, and ROS1. Additionally, we will discuss novel strategies driving the rechallenge of EGFR antibodies and the incorporation of newer anti-angiogenic agents in the therapeutic armamentarium.

Examination of testicular lumicrine regulation of activins and immunoregulatory genes in the epididymal caput

BACKGROUND

Immunoregulatory genes encoding activin A (Inhba) and B (Inhbb), and indolamine 2,3-dioxygenase-1 (Ido1) are highly expressed in the murine caput epididymidis, which also has a network of intraepithelial mononuclear phagocytes. This environment is postulated to promote immunological tolerance to epididymal sperm. The factors regulating the immunoregulatory agents in the epididymal caput are poorly understood.

OBJECTIVES

This study aimed to investigate the potential role of testicular lumicrine factors in regulating activin and other immune-related genes in the caput epididymidis.

MATERIALS AND METHODS

The efferent ducts in adult C57/Bl6 mice were exposed and ligated bilaterally. Serum and tissues were collected seven days later. Animals with bilateral sham ligation and animals with no ligations (collectively referred to as the "intact" group) were used as controls.

RESULTS

Pressure-induced seminiferous epithelial damage due to intratubular fluid accumulation was observed in all ligated testes. Testicular inhibin was significantly increased and testosterone was elevated in some animals following bilateral ligation, but serum testosterone, serum LH, and serum inhibin were normal. Ligation caused epithelial regression in the initial segment, with similar but less severe effects in other caput segments. Activin A staining by immunohistochemistry in the epithelium was reduced in bilateral ligation, particularly in the initial segment, with moderately reduced staining intensity in the rest of the caput. Inhba expression within the caput was not significantly affected by bilateral ligation, but Inhbb was reduced by more than 60%. Transcripts encoding the macrophage-specific receptor Cx3cr1 were significantly reduced following bilateral ligation, but other immune cell markers, Ido1, and inflammatory genes were unaffected.

CONCLUSION

These data indicate that testicular lumicrine secretion regulates several genes that are preferentially expressed in the initial segment, but has marginal effects on genes such as those encoding activin A and IDO1, which are expressed more widely in the caput.

Three-dimensional analysis of mesonephric tubules remodeling into efferent tubules in the male mouse embryo

BACKGROUND

Spermatozoa are transported to the epididymal duct through efferent tubules. Although the origin of the efferent tubules is thought to be mesonephric tubules (MTs), their detailed developmental process, for example, where the rete testis and efferent tubules are connected, is unclear. We investigated the structural changes of the MTs in the male mouse embryo using a three-dimensional reconstruction method.

RESULTS

Three to six MTs were connected to the Wolffian duct, and some of them branched, resulting in five to nine tips. Rete cells contacted the three to six tips. The MTs showed a folded shape when the gonadal fate was determined. After the testis development started, they became short and straight but emerged as long and twisting by birth. Before birth, the efferent duct was composed of MTs and a cranial portion of the folded Wolffian duct.

CONCLUSIONS

The contact between the rete testis and efferent tubules is possibly established at the tip of each MT. The MTs regress after gonadal fate is determined but is remodeled to the twisting efferent tubules by birth. The efferent tubules are composed of the MTs but also a cranial portion of the folded Wolffian duct in the mouse.

NELL2 modulates cell proliferation and apoptosis via ERK pathway in the development of benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) is a quite common illness but its etiology and mechanism remain unclear. Neural epidermal growth factor-like like 2 (NELL2) plays multifunctional roles in neural cell growth and is strongly linked to the urinary tract disease. Current study aims to determine the expression, functional activities and underlying mechanism of NELL2 in BPH. Human prostate cell lines and tissues from normal human and BPH patients were utilized. Immunohistochemical staining, immunofluorescent staining, RT-polymerase chain reaction (PCR) and Western blotting were performed. We further generated cell models with NELL2 silenced or overexpressed. Subsequently, proliferation, cycle, and apoptosis of prostate cells were determined by cell counting kit-8 (CCK-8) assay and flow cytometry analysis. The epithelial-mesenchymal transition (EMT) and fibrosis process were also analyzed. Our study revealed that NELL2 was up-regulated in BPH samples and localized in the stroma and the epithelium compartments of human prostate tissues. NELL2 deficiency induced a mitochondria-dependent cell apoptosis, and inhibited cell proliferation via phosphorylating extracellular signal-regulated kinase 1/2 (ERK1/2) activation. Additionally, suppression of ERK1/2 with U0126 incubation could significantly reverse NELL2 deficiency triggered cell apoptosis. Consistently, overexpression of NELL2 promoted cell proliferation and inhibited cell apoptosis. However, NELL2 interference was observed no effect on EMT and fibrosis process. Our novel data demonstrated that up-regulation of NELL2 in the enlarged prostate could contribute to the development of BPH through enhancing cell proliferation and inhibited a mitochondria-dependent cell apoptosis via the ERK pathway. The NELL2-ERK system might represent an important target to facilitate the development of future therapeutic approaches in BPH.

Deleterious variants in genes regulating mammalian reproduction in Neanderthals, Denisovans and extant humans

STUDY QUESTION

Were Neanderthals and Denisovans (referred here also as extinct hominidae) carrying deleterious variants in genes regulating reproduction?

SUMMARY ANSWER

The majority of extinct hominidae analyzed here, presented a considerable number of deleterious variants per individual in proteins regulating different aspects of reproduction, including gonad and uterine function, and gametogenesis.

WHAT IS KNOWN ALREADY

Neanderthals, Denisovans and extant humans were interfertile and hybridized while occupying geographically overlapping areas in Europe and Asia. This is evidenced by the small archaic genome component (average ∼2%) present in non-African extant humans.

STUDY DESIGN, SIZE, DURATION

The genome of eight extinct hominidae, together with five human genome databases, plus 44 mothers and 48 fathers (fertile controls), were screened to look for deleterious variants in 1734 protein-coding genes regulating reproduction.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Ancient DNA from six Neanderthals and two Denisovans dated between ∼82 000 and 43 000 calibrated years was retrieved from the public European Nucleotide Archive. The hominins analyzed include Altai, Vindija 33.15, 33.19, 33.25 and 33.26, El Sidron 1253, Denisova 3 and 11. Their DNA was analyzed using the CLC Genomics Workbench 12, by mapping overlapping paired-end reads (Illumina, FASTQ files) to the human genome assembly GRCh37 (hg19) (Vindija 33.19, 33.25, 33.26, Denisova 3 and Denisova 11) or by analyzing BAM files (Altai, El Sidron 1253 and Vindija 33.15) (human genome reference, GRCh37 (hg19)). Non-synonymous reproductive variants were classified as deleterious or tolerated (PolyPhen-2 and SIFT analyses) and were compared to deleterious variants obtained from extant human genome databases (Genome Aggregation Database (GnomAD), 1000 Genomes, the Haplotype Map (HapMap), Single Nucleotide Polymorphism Database (dbSNPs)) across different populations. A genetic intersection between extant or extinct DNA variants and other genetic disorders was evaluated by annotating the obtained variants with the Clinical Variant (ClinVar) database.

MAIN RESULTS AND THE ROLE OF CHANCE

Among the eight extinct hominidae analyzed, a total of 9650 non-synonymous variants (only coverage ≥20 reads included; frameshift mutations were excluded) in 1734 reproductive protein-coding genes were found, 24% of which were classified as deleterious. The majority (73%) of the deleterious alleles present in extant humans that are shared between extant humans and extinct hominidae were found to be rare (<1%) in extant human populations. A set of 8044 variants were found uniquely in extinct hominidae. At the single-gene level, no extinct individual was found to be homozygous for deleterious variants in genes necessary for gamete recognition and fusion, and no higher chance of embryo-lethality (calculated by Mendelian Genetics) was found upon simulated mating between extant human and extinct hominidae compared to extant human-extant human. However, three of the eight extinct hominidae were found to be homozygous for 48-69 deleterious variants in 55 genes controlling ovarian and uterine functions, or oogenesis (AKAP1, BUB1B, CCDC141, CDC73, DUSP6, ESR1, ESR2, PATL2, PSMC3IP, SEMA3A, WT1 and WNT4). Moreover, we report the distribution of nine Neanderthal variants in genes associated with a human fertility phenotype found in extant human populations, one of which has been associated with polycystic ovarian syndrome and primary congenital glaucoma.

LIMITATIONS, REASONS FOR CAUTION

While analyzing archaic DNA, stringent filtering criteria were adopted to screen for deleterious variants in Neanderthals and Denisovans, which could result in missing a number of variants. Such restraints preserve the potential for detection of additional deleterious variants in reproductive proteins in extinct hominidae.

WIDER IMPLICATIONS OF THE FINDINGS

This study provides a comprehensive overview of putatively deleterious variants in extant human populations and extinct individuals occurring in 1734 protein-coding genes controlling reproduction and provides the fundaments for future functional studies of extinct variants in human reproduction.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the Department of Biological Science and by the Office of Research and Sponsored Programs at the University of Tulsa (Faculty Research Grant and Faculty Research Summer Fellowship) to M.A. and the University of Tulsa, Tulsa Undergraduate Research Challenge (TURC) program to E.L.; no conflict of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.