Van Gogh-like 2 (Vangl2), a core planar cell polarity (PCP) component, regulates spermatogenesis in Eriocheir sinensis, yet the molecular basis of its asymmetric membrane targeting remains uncharacterized. Here, we identified a conserved trafficking module consisting of the microtubule motor Es-Kif13 and the adaptor protein complex Es-AP-1 (β1/γ1/μ1/σ2), which assembled into a tripartite complex with Es-Vangl2 in E. sinensis testis. Knockdown of Es-Kif13 or Es-AP-1β1 disrupted polarized Es-Vangl2 localization without altering protein levels, leading to its cytoplasmic dispersion. This mislocalization suppressed the RhoA/Rock/MLC2 signaling axis and triggered stage-specific F-actin disorganization in spermatocytes via epidermal growth factor receptor pathway substrate 8 (Eps8) dysregulation, thereby phenocopying Es-Vangl2 deficiency. Subsequently, the hemolymph-testis barrier (HTB) integrity collapsed, as evidenced by biotin tracer leakage and junctional protein remodeling. These defects culminated in spermatogenic failure, characterized by seminiferous epithelium vacuolization and spermiation obstruction. Our findings establish Es-Kif13/Es-AP-1-mediated Es-Vangl2 trafficking as an evolutionarily conserved mechanism governing PCP-directed cytoskeletal dynamics and barrier function, with disruption directly impairing germline niche maintenance in crustaceans.

Male reproductive health, particularly the regulation of spermatogenesis, is controlled by a complex combination of factors, including luteinizing hormone (LH) and its effects on Leydig cells (LCs). LH stimulates testosterone synthesis in LCs, which is critical for maintaining spermatogenesis and male fertility. This review examines the pathways through which LH regulates testosterone production, LC proliferation, differentiation, and circadian rhythm in human and non-human species. In particular, the signaling pathways of luteinizing hormone involved in testosterone production are discussed. Additionally, we explore LH’s role in sperm maturation and quality, emphasizing its clinical implications in treating hypogonadotropic hypogonadism and diagnosing gonadal dysfunctions such as androgen insensitivity syndrome and precocious puberty. Furthermore, the potential of LH in assisted reproductive technologies for improving sperm quality is discussed. By highlighting key molecular mechanisms, this work provides insights into the therapeutic potential of LH in addressing male infertility and conditions of LC dysfunction.

Mitochondria play essential roles for animal reproduction, influencing not only cellular energetics but also gamete quality, inheritance and evolutionary patterns. Currently, most research still focuses on chordates or mitochondrial diseases and their impact on the health of germ cells. However, few studies focus on integrative synthesis that connect comparative morphology, inheritance mechanisms and evolutionary theory. In this review, we integrate cross-phyla evidence to explore two interconnected dimensions: the fate of mitochondria during gametogenesis and the strategy shaping their evolution. We compare mitochondrial morphology, distribution, and metabolic strategies in gametogenesis, revealing how these traits align with reproductive modes and ecological adaptations. Then we further discuss how mitochondrial genome evolution, bottleneck effects and mito-nuclear coevolution contribute to germline stability and maternal inheritance. Special attention is given to exceptional systems such as Doubly Uniparental Inheritance (DUI) in bivalves, which challenges conventional mode of strictly maternal transmission and illuminates the flexibility of mito-nuclear evolution. Altogether, these perspectives highlight mitochondria as gatekeepers and evolutionary recorders in the reproductive systems across metazoans, providing a unifying framework for future research across ecology, evolution and molecular biology.

The roles of PIWI in mammalian spermatogenesis have been well-studied but are largely unknown in invertebrates such as the Chinese mitten crab (Eriocheir sinensis), which produces non-flagellar sperm. Here, we demonstrate that knockdown of PIWIs significantly promotes the proliferation of spermatogonia and the transformation into spermatocytes. Expression of PIWIs in HEK 293T significantly inhibits cell proliferation through the Wnt-signaling pathway. PIWIs suppress transcriptional activity of the Wnt pathway to down-regulate Cyclin D and Cyclin E by inhibiting β-catenin and the phosphorylation of β-catenin at Ser552. The intracellular structure of the adherens junction is destroyed by PIWIs due to downregulated α-catenin, β-catenin, and ZO1. Overall, our results suggest that PIWIs regulate spermatogonia self-renewal and differentiation through inhibiting the Wnt-signaling pathway and stabilize the structure of the adherens junction by regulating the expression and location of α-catenin, β-catenin, and ZO1 in E. sinensis, which are different from the functions in mammals. Our findings revealed novel functions and molecular mechanisms of PIWIs in regulating spermatogonia self-renewal and differentiation during the Crustacea spermatogenesis.

Bisphenol A (BPA) is a well-known environmental pollutant, particularly in aquatic systems. The hazards of BPA exist in the following aspects, such as endocrine interference, reproductive system impact, development problems and metabolic disorders, and so on. As an economically important aquatic crustacean, Eriocheir sinensis lives in a wide range of BPA contaminated water environments. The possible damage caused by BPA to E. sinensis, especially reproductive damage, has not been reported as yet. We carried out experiments on reproductive damage, the results indicated that different concentrations of BPA not only lead to a decrease of testes weight but also caused abnormal spermatogenesis. After low concentrations of BPA was added, low concentrations of BPA led to apoptosis as well as proliferation inhibition of spermatogenic cells through the esERR-esKIF4A pathway. In a substitute experiment, BPB and BPF were probably not suitable substitutes for BPA. All in all, we demonstrated that BPA was harmful to the spermatogenesis of E. sinensis at environmental concentrations, and stimulated oxidative stress which to cause apoptosis and proliferation inhibition through the esERR-esKIF4A pathway. While its substitutes BPB and BPF were unreliable.

Hedgehog (HH) signaling has been researched for decades and Hedgehog has 3 homologs: Sonic Hedgehog (Shh), Indian Hedgehog (Ihh), and Desert Hedgehog (Dhh). Dhh is the one involved in male gonad and germ cell development. The distribution of molecules in Hedgehog signaling in testis indicated that Hedgehog signaling executes important functions during testis development. The patients with Dhh signaling deficiency develop dysgenesis of gonads and hormone production which demands further exploration of gonad HH signaling. Some results proved the indispensable roles of HH signaling in gonad and germ cell development and the interaction with hormones. This review evaluates HH functions in the testis and how HH affects and is affected by hormones and provides novel insights about HH signaling to the readers.

Hedgehog (HH) signaling plays important roles in the development of the nervous system (Sonic hedgehog), bone, cartilage (Indian Hedgehog) and testis (Desert Hedgehog). Research on HH and testes has mostly been conducted in HH-knockout mice and rats, etc. The relationship between HH and cellular junctions has mostly been found in the nervous system and intestine. However, few research studies concerning the link between HH signaling and cell junctions in testis function have been reported. We identified the members of HH signaling that are involved in Eriocheir sinensis testes: HH, Smoothen, Patched, Kif27 and Ci. HH has only one homolog in E. sinensis and is expressed in several types of germ cells in the testes. We found that Kif27 colocalized with Ci in the testes. The knockdown of HH induced enlarged interstitial spaces of the seminiferous tubules. A biotin–streptavidin immunofluorescence experiment indicated that the hemolymph–testis barrier (HTB) was disrupted. Western blot results showed that pinin, HH signaling and cell proliferation- and apoptosis-related protein levels were downregulated. Further immunofluorescent results showed the dislocation of several junction proteins, the abnormality of F-actin and the slowdown of germ cell proliferation and apoptosis. While β-catenin entered the spermatocyte nucleus, it did not activate Wnt-β-catenin signaling, which indicated that the disturbance of the cell cycle in germ cells was not caused by Wnt-β-catenin signaling. In summary, HH signaling plays some roles beyond our understanding in the regulation of the HTB and the germ cell cycle in E. sinensis testes.

Background The tumour microenvironment (TME) significantly influences intercellular communication, with several secreted factors activating both tumour cells and fibroblasts. Connexin43 (Cx43), a crucial gap junction protein, exhibits a significant regulatory role in tumourigenesis; however, the underlying regulatory mechanisms in colorectal cancer (CRC) are not fully understood.Methods Transwell co-culture system was utilized to evaluate fibroblast-mediated effects on CRC cells. Immunohistochemical analysis was conducted on clinical specimens. Cell migration and invasion capabilities were measured using Transwell assays. Subcellular localization was assessed via immunofluorescence. Protein interactions were validated by co-immunoprecipitation.Results The Wnt signalling pathway was activated in the co-culture of CRC cells and fibroblasts. Nuclear Cx43 upregulation was detected and confirmed as a pro-oncogenic factor via prognostic analysis of patient samples. Therefore, although Cx43 on the cell membrane serves as a tumour suppressor, the nuclear translocation of Cx43 has an important influence on the Wnt signalling pathway and promotes CRC progression. Nuclear translocation of Cx43 during malignant progression has a significant effect on metastasis and is regulated by secreted TGF-β. Distinct nuclear translocation patterns of Cx43 observed across CRC cell lines suggest potential regulation by S368 phosphorylation. Co-immunoprecipitation confirmed Cx43/β-catenin interaction, revealing its role in facilitating β-catenin nuclear accumulation.Conclusion We systematically identified nuclear Cx43 as a factor promoting CRC progression. These findings highlight the novel mechanism involving the nuclear translocation of Cx43 as a promoting factor in CRC progression, and enhance our understanding of the interplay between the TME and CRC progression.

E. sinensis is an animal model for studying the reproduction and development of crustaceans. In this study, we knocked down the Es-Kif2a gene by injecting dsRNA into E. sinensis and inhibited Es-Plk1 gene expression by injecting PLK1 inhibitor BI6727 into E. sinensis. Then, the cell proliferation level, apoptosis level, and PI3K/AKT signaling expression level were detected. Our results showed that the proliferation level of spermatogenic cells decreased, while the apoptosis level increased after Es-Kif2a knockdown or Es-Plk1 inhibition. In order to verify whether these changes are caused by regulating the PI3K/AKT pathway, we detected the expression of PI3K and AKT proteins after Es-Kif2a knockdown or Es-Plk1 inhibition. Western Blot showed that in both the Es-Kif2a knockdown group and the Es-Plk1 inhibition group, the expression of PI3K and AKT proteins decreased. In addition, immunofluorescence showed that Es-KIF2A and Es-PLK1 proteins were co-localized during E. sinensis spermatogenesis. To further explore the upstream and downstream relationship between Es-KIF2A and Es-PLK1, we detected the expression level of Es-PLK1 after Es-Kif2a knockdown as well as the expression level of Es-KIF2A after Es-Plk1 inhibition. Western Blot showed that the expression of Es-PLK1 decreased after Es-Kif2a knockdown, while there was no significant change of Es-KIF2A after Es-Plk1 inhibition, indicating that Es-PLK1 may be a downstream factor of Es-KIF2A. Taken together, these results suggest that Es-KIF2A upregulates the PI3K/AKT signaling pathway through Es-PLK1 during the spermatogenesis of E. sinensis, thereby affecting the proliferation and apoptosis levels of spermatogenic cells.

The hemolymph–testis barrier (HTB) is a reproduction barrier in Crustacea, guaranteeing the safe and smooth process of spermatogenesis, which is similar to the blood–testis barrier (BTB) in mammals. The MAPK signaling pathway plays an essential role in spermatogenesis and maintenance of the BTB. However, only a few studies have focused on the influence of MAPK on crustacean reproduction. In the present study, we knocked down and inhibited MAPK in Eriocheir sinensis. Increased defects in spermatogenesis were observed, concurrently with a damaged HTB. Further research revealed that es-MMP14 functions downstream of ERK and p38 MAPK and degrades junctional proteins (Pinin and ZO-1); es-CREB functions in the ERK cascade as a transcription factor of ZO-1. In addition, when es-MMP14 and es-CREB were deleted, the defects in HTB and spermatogenesis aligned with abnormalities in the MAPK. However, JNK impacts the integrity of the HTB by changing the distribution of intercellular junctions. In summary, the MAPK signaling pathway maintains HTB integrity and spermatogenesis through es-MMP14 and es-CREB, which provides insights into the evolution of gene function during barrier evolution.

As a key planar cell polarity protein, Van Gogh-like 2 (Vangl2) is essential for mammalian spermatogenesis. As a decapod crustacean, Eriocheir sinensis exhibits distinct spermatogenic processes due to its unique seminiferous tubule morphology and hemolymph-testis barrier (HTB). To determine whether Vangl2 performs analogous functions in E. sinensis, we identified the Es-Vangl2. Es-Vangl2 exhibited high expression and wide distribution in the testes, indicating its crucial involvement in spermatogenesis. Following targeted knockdown of Es-Vangl2 in vivo, the structure of seminiferous tubules was disrupted, characterized by vacuolization of the germinal zone and obstruction of spermatozoon release. Concurrently, the integrity of the HTB was compromised, accompanied by reduced expression and aberrant localization of junction proteins. More importantly, the regulatory influence of Es-Vangl2 was manifested through modulating the organization of microfilaments, a process mediated by epidermal growth factor receptor pathway substrate 8 (Eps8). Further studies demonstrated that these phenotypes resulting from Es-Vangl2 knockdown were attributed to the inhibition of Rock signaling pathway activity, which was verified by the Es-Rock interference and Y27632 inhibition assays. In summary, the findings highlight the pivotal role of Es-Vangl2 in stabilizing HTB integrity by regulating Eps8-mediated actin remodeling through the Rock signaling pathway in the spermatogenesis of E. sinensis.

As a pathway that plays a role in nutrient absorption, anabolic response, cell growth and survival, the important role of AKT/mTOR in tumorigenesis has also come to light. For cancer patients, most deaths are caused by the growth of metastatic tumors outside the primary focus. Therefore, migration and invasion in the late stage of tumor progression are the main unresolved issues in the study of tumor pathogenesis, and AKT/mTOR has been found to participate in the migration and invasion of cancer cells, which means that the study of this pathway may contribute to a solution for the problem. Because of its extensive and complex functions in the organism, this pathway can be regulated by a variety of different signals in the body, and then realize its function through different downstream signal molecules. This article reviews the proteins that can indirectly affect this pathway by regulating the common upstream signaling molecules of this pathway, and the proteins that can directly affect the level of phosphorylation of AKT/mTOR in cancer cells. We also review the proteins that can co-regulate this pathway and its downstream pathways. Through this study, we hope to gain a deeper understanding of the regulatory mechanism of the AKT/mTOR pathway in cancer cells, in hopes of finding effective and harmless cancer treatment targets in the future.

β-CATENIN is an evolutionarily conserved multifunctional molecule that maintains cell adhesion as a cell junction protein to safeguard the integrity of the mammalian blood-testes barrier, and also regulates cell proliferation and apoptosis as a key signaling molecule in the WNT/β-CATENIN signaling pathway. In the crustacean Eriocheir sinensis, Es-β-CATENIN has been shown to be involved in spermatogenesis, but the testes of E. sinensis have large and well-defined structural differences from those of mammals, and the impact of Es-β-CATENIN in them is still unknown. In the present study, we found that Es-β-CATENIN, Es-α-CATENIN and Es-ZO-1 interact differently in the testes of the crab compared to mammals. In addition, defective Es-β-CATENIN resulted in increased Es-α-CATENIN protein expression levels, distorted and deformed F-ACTIN, and disturbed localization of Es-α-CATENIN and Es-ZO-1, leading to loss of hemolymph-testes barrier integrity and impaired sperm release. In addition to this, we also performed the first molecular cloning and bioinformatics analysis of Es-AXIN in the WNT/β-CATENIN pathway to exclude the effect of the WNT/β-CATENIN pathway on the cytoskeleton. In conclusion, Es-β-CATENIN participates in maintaining the hemolymph-testes barrier in the spermatogenesis of E. sinensis.

Mammalian target of rapamycin (mTOR) is a crucial signaling protein regulating a range of cellular events. Numerous studies have reported that the mTOR pathway is related to spermatogenesis in mammals. However, its functions and underlying mechanisms in crustaceans remain largely unknown. mTOR exists as two multimeric functional complexes termed mTOR complex 1 (mTORC1) and mTORC2. Herein, we first cloned ribosomal protein S6 (rpS6, a downstream molecule of mTORC1) and protein kinase C (PKC, a downstream effector of mTORC2) from the testis of Eriocheir sinensis . The dynamic localization of rpS6 and PKC suggested that both proteins may be essential for spermatogenesis. rpS6 / PKC knockdown and Torin1 treatment led to defects in spermatogenesis, including germ cell loss, retention of mature sperm and empty lumen formation. In addition, the integrity of the testis barrier (similar to the blood-testis barrier in mammals) was disrupted in the rpS6 / PKC knockdown and Torin1 treatment groups, accompanied by changing in expression and distribution of junction proteins. Further study demonstrated that these findings may result from the disorganization of filamentous actin (F-actin) networks, which were mediated by the expression of actin-related protein 3 (Arp3) rather than epidermal growth factor receptor pathway substrate 8 (Eps8). In summary, our study illustrated that mTORC1/rpS6 and mTORC2/PKC regulated spermatogenesis via Arp3-mediated actin microfilament organization in E. sinensis .

There are two kinds of toxins in sea anemones: neurotoxins and pore forming toxins. As a representative of the sodium channel toxin, the neurotoxin ATX II in neurotoxin mainly affects the process of action potential and the release of transmitter to affect the inactivation of the sodium channel. As the representatives of potassium channel toxins, BgK and ShK mainly affect the potassium channel current. EqTx and Sticholysins are representative of pore forming toxins, which can form specific ion channels in cell membranes and change the concentration of internal and external ions, eventually causing hemolytic effects. Based on the above mechanism, toxins such as ATX II can also cause toxic effects in tissues and organs such as heart, lung and muscle. As an applied aspect it was shown that sea anemone toxins often have strong toxic effects on tumor cells, induce cancer cells to enter the pathway of apoptosis, and can also bind to monoclonal antibodies or directly inhibit relevant channels for the treatment of autoimmune diseases.

The myosin motor protein myosin VI plays an essential role in mammalian spermatogenesis, however, the effects of myosin VI on male reproduction in Crustacea remain obscure. We identified the macromolecule es-Myosin VI in Eriocheir sinensis, and studied it by multiple methods. It co-localized with F-actin and was highly expressed in the testis. We interfered es-Myosin VI using dsRNA in vivo, an apparent decrease in spermatozoa count was detected. We also found that the MAPK signalling pathway was changed, subsequently causing disruption of intercellular junctions and damage to the functional hemolymph-testis barrier. We observed that luteinizing hormone receptor es-LHR was located within seminiferous tubules, which was different from the expression in mammals. Es-LHR could bind with es-Myosin VI in testis of E. sinensis, its localization was significantly altered when es-Myosin VI was deleted. Moreover, we obtained consistent results for the MAPK signalling pathway and spermatogenesis defects between the es-LHR and es-Myosin VI knockdown groups. In summary, our research demonstrated that knockdown of es-Myosin VI disturbed the intercellular junction and HTB function via the MAPK signalling pathway by changing the localization of es-LHR in the testis of E. sinensis, which was the potential reason for its negative impact on spermatogenesis.

Recent findings found that TiO2 nanoparticles (TiO2-NPs) have male reproductive toxicity. However, few reports have studied the toxicity of TiO2-NPs in crustaceans. In this study, we first chose the freshwater crustacean Eriocheir sinensis (E. sinensis) to explore the male toxicity of TiO2-NP exposure and the underlying mechanisms. Three nm and 25 nm TiO2-NPs at a dose of 30 mg/kg bw induced apoptosis and damaged the integrity of the haemolymph-testis-barrier (HTB, a structure similar to the blood-testis-barrier) and the structure of the seminiferous tubule. The 3-nm TiO2-NPs caused more severe spermatogenesis dysfunction than the 25-nm TiO2-NPs. We initially confirmed that TiO2-NP exposure affected the expression patterns of adherens junctions (α-catenin and β-catenin) and induced tubulin disorganization in the testis of E. sinensis. TiO2-NP exposure caused reactive oxygen species (ROS) generation and an imbalance of mTORC1-mTORC2 (mTORC1/rps6/Akt levels were increased, while mTORC2 activity was not changed). After using the ROS scavenger NAC to inhibit ROS generation, both the mTORC1-mTORC2 imbalance and alterations in AJs were rescued. More importantly, the mTORC1 inhibitor rapamycin abolished mTORC1/rps6/Akt hyperactivation and partially restored the alterations in AJs and tubulin. Collectively, the mTORC1-mTORC2 imbalance induced by TiO2-NPs was involved in the mechanism of AJ and HTB disruption, resulting in spermatogenesis in E. sinensis.

The phosphoinositide-3-kinase/Akt (PI3K/AKT) signaling pathway is crucial for Sertoli cell development and completing spermatogenesis. Its main role is to promote proliferation and inhibit apoptosis. Many factors activate the PI3K/AKT pathway, like hormones, such as follicle stimulating hormone (FSH), androgen, estrogen, insulin to name a few. Many of these factors have receptors inside or on the surface of Sertoli cells (SCs). This review summarizes how these hormones directly regulate the PI3K/AKT signaling pathway in SCs, which in turn affects SC proliferation and differentiation. Further, hormone-mediated PI3K/AKT signaling also stimulates SC secretion, which is essential for germ cell development, suggesting an indirect role of PI3K/AKT signaling during spermatogenesis. These functions include promoting spermatogonia proliferation and differentiation, meiosis of spermatocytes, sperm maturation, and their release. This review also provides potential hints for clinically treating male infertility issues like cryptorchidism and Sertoli cell-only syndrome.

Spermatogenesis is a complicated process that includes spermatogonia differentiation, spermatocytes meiosis, spermatids spermiogenesis and final release of spermatozoa. Actin-related protein 3 (Arp3) and epidermal growth factor receptor pathway substrate 8 (Eps8) are two actin binding proteins that regulate cell adhesion in seminiferous tubules during mammalian spermatogenesis. However, the functions of these two proteins during spermatogenesis in nonmammalian species, especially Crustacea, are still unknown. Here, we cloned es-Arp3 and es-Eps8 from the testis of Chinese mitten crab Eriocheir sinensis. es-Arp3 and es-Eps8 were located in spermatocytes, spermatids and spermatozoa. Knockdown of es-Arp3 and es-Eps8 in vivo caused morphological changes to seminiferous tubules including delayed spermatozoa release, shedding of germ cells and vacuoles. Filamentous-actin (F-actin) filaments network was disorganized due to deficiency of es-Arp3 and es-Eps8. Accompanying this, four junctional proteins (α-catenin, β-catenin, pinin and ZO1) displayed abnormal expression levels as well as penetrating biotin signals in seminiferous tubules. We also used the Arp2/3 complex inhibitor CK666 to block es-Arp3 activity and supported es-Arp3 knockdown results. In summary, our study demonstrated for the first time that es-Arp3 and es-Eps8 are important for spermatogenesis via regulating microfilament-mediated cell adhesion in Eriocheir sinensis.

Cell adhesion and stable signaling regulation are fundamental ways of maintaining homeostasis. Among them, the Wnt/β-CATENIN signaling plays a key role in embryonic development and maintenance of body dynamic homeostasis. At the same time, the key signaling molecule β-CATENIN in the Wnt signaling can also function as a cytoskeletal linker protein to regulate tissue barriers, cell migration, and morphogenesis. Dysregulation of the balance between Wnt signaling and adherens junctions can lead to disease. How β-CATENIN maintains the independence of these two functions, or mediates the interaction and balance of these two functions, has been explored and debated for a long time. In this study, we will focus on five aspects of β-CATENIN chaperone molecules, phosphorylation of β-CATENIN and related proteins, epithelial mesenchymal transition, β-CATENIN homolog protein γ-CATENIN and disease, thus deepening the understanding of the Wnt/β-CATENIN signaling and the homeostasis between cell adhesion and further addressing related disease problems.