Busulfan Suppresses Autophagy in Mouse Spermatogonial Progenitor Cells via mTOR of AKT and p53 Signaling Pathways

SDF-1/CXCR4 axis maintains porcine prospermatogonia undifferentiated state through regulation of transcription suppressor PLZF

Prospermatogonia (ProSGs), the progenitors of spermatogonial stem cells in neonatal testes, undergo critical migration to the testicular microenvironment-a fundamental process for testicular development and subsequent spermatogenic capacity. The SDF-1/CXCR4 chemokine axis serves as an essential molecular guidance mechanism, directing ProSGs toward the basal membrane of seminiferous tubules. Nevertheless, the precise molecular mechanisms governing this axis remain incompletely understood. Utilizing a porcine in vitro model system, this investigation elucidated the molecular mechanisms underlying the SDF-1/CXCR4 axis in ProSGs fate determination. Through integrated molecular and transcriptomic analyses, we investigated the consequences of CXCR4 inhibition on ProSG cellular dynamics. Our findings demonstrated that the SDF-1/CXCR4 axis exerts regulatory control over ProSGs differentiation via the PI3K-AKT-AP-1 signaling cascade. This regulation significantly influences the transcriptional landscape of ProSGs, particularly modulating the expression of PLZF, a crucial suppressor of spermatogonial differentiation, and DMRT1, an essential mediator of germ cell differentiation. These findings elucidate the molecular mechanisms orchestrating ProSGs homing and emphasize the significance of maintaining male reproductive competence. Furthermore, this research could enhance our understanding of ProSGs biology and its relationship to boar fertility, while potentially facilitating the development of innovative reproductive technologies and sustainable livestock management strategies.

Autophagy mediated tubulobulbar complex components degradation is required for spermiation

Spermiation is the process that releases mature spermatids from Sertoli cells into the lumen of the seminiferous tubule. Tubulobulbar complexes (TBCs) are elaborate cytoskeleton-related structures that are indispensable for spermiation. Despite well-defined ultrastructural events, the molecular regulation of TBCs during spermiation remains largely unknown. Here, we show that autophagy is active in TBC regions, and impaired autophagy in Sertoli cells affects spermiation. Further studies demonstrated that many TBC components bound to LC3 and could be selectively degraded through the autophagy-lysosome pathway. Perturbed autophagy impaired the degradation of some TBC components in Sertoli cells, such as VCL and CTTN, and led to the accumulation of TBC components surrounding the spermatid head, which may be associated with the sperm-releasing defect. Together, our results reveal that autophagy is essential for the TBC components degradation in mouse Sertoli cells and define a functional role of autophagy during spermiation.

The role of p53 in male infertility

The tumor suppressor p53 is a transcription factor involved in a variety of crucial cellular functions, including cell cycle arrest, DNA repair and apoptosis. Still, a growing number of studies indicate that p53 plays multiple roles in spermatogenesis, as well as in the occurrence and development of male infertility. The representative functions of p53 in spermatogenesis include the proliferation of spermatogonial stem cells (SSCs), spermatogonial differentiation, spontaneous apoptosis, and DNA damage repair. p53 is involved in various male infertility-related diseases. Innovative therapeutic strategies targeting p53 have emerged in recent years. This review focuses on the role of p53 in spermatogenesis and male infertility and analyses the possible underlying mechanism involved. All these conclusions may provide a new perspective on drug intervention targeting p53 for male infertility treatment.

Ferritinophagy-mediated ferroptosis of spermatogonia is involved in busulfan-induced oligospermia in the mice

Busulfan, a bifunctional alkylated chemotherapeutic agent, has male reproductive toxicity and induce oligospermia, which is associated with ferroptosis. However, the specific target cells of busulfan-induced oligospermia triggered by ferroptosis are largely elusive, and the detailed mechanisms also require further exploration. In the present study, busulfan (0.6, and 1.2 mM, 48 h) causes ferroptosis in GC-1 spg cells through inducing Fe2+, ROS and MDA accumulation and functional inhibition of Xc-GSH-GPX4 antioxidant system. After inhibition of ferroptosis by Fer-1 (1 μM, pretreatment for 2 h) or DFO (10 μM, pretreatment for 2 h) reverses busulfan-induced destructive effects in GC-1 spg cells. Furthermore, using RNA-seq and Western blotting, we found that busulfan promotes autophagy-dependent ferritin degradation, as reflected by enriching in autophagy, increased LC3 II, Beclin1 and NCOA4, as well as decreased P62 and ferritin heavy chain 1 (FTH1). Ultimately, GC-1 spg cells and Balb/c mice were treated with busulfan and/or 3-MA, the inhibitor of autophagy. The results displayed that inhibition of autophagy relieves busulfan-induced FTH1 degradation and then blocks the occurrence of ferroptosis in GC-1 spg cells and testicular spermatogonia, which subsequently alleviates busulfan-caused testicular damage and spermatogenesis disorders. In summary, these data collectively indicated that ferroptosis of spermatogonia is involved in busulfan-induced oligospermia and mediated by autophagy-dependent FTH1 degradation, identifying a new target for the therapy of busulfan-induced male infertility.

mTOR signalling pathway in stem cell bioactivities and angiogenesis potential

The mammalian target of rapamycin (mTOR) is a protein kinase that responds to different stimuli such as stresses, starvation and hypoxic conditions. The modulation of this effector can lead to the alteration of cell dynamic growth, proliferation, basal metabolism and other bioactivities. Considering this fact, the mTOR pathway is believed to regulate the diverse functions in several cell lineages. Due to the pleiotropic effects of the mTOR, we here, hypothesize that this effector can also regulate the bioactivity of stem cells in response to external stimuli pathways under physiological and pathological conditions. As a correlation, we aimed to highlight the close relationship between the mTOR signalling axis and the regenerative potential of stem cells in a different milieu. The relevant publications were included in this study using electronic searches of the PubMed database from inception to February 2023. We noted that the mTOR signalling cascade can affect different stem cell bioactivities, especially angiogenesis under physiological and pathological conditions. Modulation of mTOR signalling pathways is thought of as an effective strategy to modulate the angiogenic properties of stem cells.

Low dose of zearalenone inhibited the proliferation of porcine prospermatogonia and transformed the physiology through cytokine-cytokine receptor interaction

Zearalenone (ZEA) is a prevalent mycotoxin functions as an endocrine disrupter to the reproductive systems of farm animals, especially in pigs. To evaluate the effect and the underlying molecular changes that occurred when the porcine germline stem cells were exposed to ZEA, prospermatogonia (ProSGs) were enriched and treated with a gradient concentration (0-10 μM) of ZEA for 2-8 days. Our results showed that the ZEA treatment inhibited the proliferation of ProSGs in a dose-dependent manner with a critical concentration at 1 μM. Transcriptome analysis revealed that the differentially expressed genes mainly concentrated on the molecular function of positive regulation of response to stimulus, and the most enriching pathway is cytokine-cytokine receptor interaction. ZEA exposure decreased a buck of cytokine/chemokine expression involved in the inflammatory response and stem cells maintenance/self-renewal, moreover, some energy expenditure and anti-apoptosis genes were also down-regulated, while the up-regulated genes were mainly connected with the innate immunity. These data demonstrate that ZEA induces multiply cellular damage and may eventually do harm to the health and fertility of animals.

Autophagy, a critical element in the aging male reproductive disorders and prostate cancer: a therapeutic point of view

Autophagy is a highly conserved, lysosome-dependent biological mechanism involved in the degradation and recycling of cellular components. There is growing evidence that autophagy is related to male reproductive biology, particularly spermatogenic and endocrinologic processes closely associated with male sexual and reproductive health. In recent decades, problems such as decreasing sperm count, erectile dysfunction, and infertility have worsened. In addition, reproductive health is closely related to overall health and comorbidity in aging men. In this review, we will outline the role of autophagy as a new player in aging male reproductive dysfunction and prostate cancer. We first provide an overview of the mechanisms of autophagy and its role in regulating male reproductive cells. We then focus on the link between autophagy and aging-related diseases. This is followed by a discussion of therapeutic strategies targeting autophagy before we end with limitations of current studies and suggestions for future developments in the field.

E-cadherin maintains the undifferentiated state of mouse spermatogonial progenitor cells via β-catenin

Background

Cadherins play a pivotal role in facilitating intercellular interactions between spermatogonial progenitor cells (SPCs) and their surrounding microenvironment. Specifically, E-cadherin serves as a cellular marker of SPCs in many species. Depletion of E-cadherin in mouse SPCs showed no obvious effect on SPCs homing and spermatogenesis.

Results

Here, we investigated the regulatory role of E-cadherin in regulating SPCs fate. Specific deletion of E-cadherin in germ cells was shown to promote SPCs differentiation, evidencing by reduced PLZF⁺ population and increased c-Kit⁺ population in mouse testes. E-cadherin loss down-regulated the expression level of β-catenin, leading to the reduced β-catenin in nuclear localization for transcriptional activity. Remarkably, increasing expression level of Cadherin-22 (CDH22) appeared specifically after E-cadherin deletion, indicating CDH22 played a synergistic effect with E-cadherin in SPCs. By searching for the binding partners of β-catenin, Lymphoid enhancer-binding factor 1 (LEF1), T-cell factor (TCF3), histone deacetylase 4 (HDAC4) and signal transducer and activator 3 (STAT3) were identified as suppressors of SPCs differentiation by regulating acetylation of differentiation genes with PLZF.

Conclusions

Two surface markers of SPCs, E-cadherin and Cadherin-22, synergically maintain the undifferentiation of SPCs via the pivotal intermediate molecule β-catenin. LEF1, TCF3, STAT3 and HDAC4 were identified as co-regulatory factors of β-catenin in regulation of SPC fate. These observations revealed a novel regulatory pattern of cadherins on SPCs fate.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13578-022-00880-w.

Human placental mesenchymal stem cells ameliorate chemotherapy-induced damage in the testis by reducing apoptosis/oxidative stress and promoting autophagy

Background

The side effects of busulfan on male reproduction are serious, so fertility preservation in children undergoing busulfan treatment is a major worldwide concern. Human placental mesenchymal stem cells (hPMSCs) have advantages such as stable proliferation and lower immunogenicity that make them an ideal material for stimulating tissue repair, especially restoring spermatogenesis. The protective effects of hPMSCs in busulfan-induced Sertoli cells and in busulfan-treated mouse testes have not been determined. Our study aimed to elaborate the protective effect and potential mechanisms of hPMSCs in busulfan-treated testes and Sertoli cells.

Methods

First, we developed a mouse model of busulfan-induced testicular toxicity in vivo and a mouse Sertoli cell line treated with busulfan in vitro to assess the protective effect and mechanisms of hPMSC treatment on spermatogenesis. Then, the length, width, and weight of the testes were monitored using Vernier calipers. Furthermore, at 1 week and 4 weeks after the transplantation of hPMSCs, histological sections of testes were stained with hematoxylin-eosin, and the seminiferous tubules with fluid-filled cavities were counted. Through ELISA analysis, testosterone levels and MDA, SOD, LDH, and CAT activities, which are associated with ROS, were detected. Markers of ROS, proliferation (Ki67), and apoptosis (Annexin V) were evaluated by FACS. Next, the fluorescence intensity of proliferation markers (BrdU and SCP3), an antioxidant marker (SIRT1), a spermatogenesis marker (PLZF), and autophagy-related genes (P62 and LC3AB) were detected by fluorescence microscopy. The mRNA expression of γ-H2AX, BRCA1, PARP1, PCNA, Ki67, P62, and LC3 was determined by qRT-PCR.

Results

hPMSCs restored disrupted spermatogenesis, promoted improved semen parameters, and increased testosterone levels, testis size, and autophagy in the testis toxicity mouse model induced by busulfan. hPMSCs suppressed the apoptosis of Sertoli cells and enhanced their rate of proliferation in vitro. Additionally, hPMSCs protected against oxidative stress and decreased oxidative damage in the testis toxicity mouse model induced by busulfan. Furthermore, hPMSCs increased the expression of proliferation genes (PCNA and KI67) and decreased the mRNA levels of apoptotic genes such as γ-H2AX, BRCA1, and PARP1.

Conclusions

This research showed that hPMSC injection ameliorated busulfan-induced damage in the testis by reducing apoptosis/oxidative stress and promoting autophagy. The present study offers an idea for a new method for clinical treatment of chemotherapy-induced spermatogenesis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02275-z.

Effect of 7-Methylsulfinylheptyl Isothiocyanate on the Inhibition of Melanogenesis in B16-F1 Cells

Skin aging, characterized by hyperpigmentation, inflammation, wrinkles, and skin cancer, is influenced by intrinsic and extrinsic factors with synergistic effects. Autophagy maintains the homeostatic balance between the degradation, synthesis, and recycling of cellular proteins and organelles, and plays important roles in several cellular and biological processes, including aging. The compound 7-methylsulfinylheptyl isothiocyanate (7-MSI) is a sulfur-containing phytochemical produced by various plants, particularly cruciferous vegetables, with reported anti-inflammatory properties and a role in pathogen defense; however, its effects on skin whitening have not been studied in detail. The purpose of this study was to observe the effects of 7-MSI on skin whitening and autophagy in cultured murine melanoma (B16-F1) cells. Western blotting was used to evaluate the impact of 7-MSI on melanogenesis-, tyrosinase-, and autophagy-associated proteins. The levels of the melanogenesis-associated protein’s microphthalmia-associated transcription factor (MITF) and tyrosinase and tyrosinase-related protein-1 were decreased by treatment with 7-MSI under melanogenesis induction. Melanin synthesis also decreased by approximately 63% after treatment with 7-MSI for 73 h, compared with that non-treated controls. In addition, autophagosome formation and the expression levels of the autophagy-related proteins mTOR, p-mTOR, Beclin-1, Atg12, and LC3 were higher in 7-MSI-treated B16-F1 cells than in non-treated cells. These results indicate that 7-MSI can inhibit melanin synthesis in B16-F1 cells by suppressing melanogenesis and autophagy activation and thus can potentially be used as a novel multifunctional cosmetic agent.

Analysis of lncRNA Expression Profile during the Formation of Male Germ Cells in Chickens

Simple Summary

The differentiation of germ cells plays an important role in sex differentiation in poultry. Therefore, it is necessary for us to explore the potential regulators in the process of germ cell development. In this study, RNA-seq was used to detect the expression profile of long non-coding RNAs (lncRNAs) in chicken embryonic stem cells (ESCs), primordial germ cells (PGCs) and spermatogonial stem cells (SSCs). The results showed that a total of 296, 280 and 357 differentially expressed lncRNAs (DELs) were screened in ESCs vs. PGCs, ESCs vs. SSCs and PGCs vs. SSCs, respectively. Functional analysis of the target genes of DELs showed that autophagy, Wnt/β-catenin, TGF-β, Notch and ErbB signaling pathways were involved in the differentiation process of male germ cells and, moreover, XLOC_612026, XLOC_612029, XLOC_240662, XLOC_362463, XLOC_023952, XLOC_674549, XLOC_160716, ALDBGALG0000001810, ALDBGALG0000002986, XLOC_657380674549, XLOC_022100 and XLOC_657380 were predicted to be the key lncRNAs in this process. Our findings could not only supply scientific data for constructing the gene regulatory network of germ cell development, but also provide new ideas for further optimizing the induction efficiency of germ cells in vitro.

Abstract

Germ cells have an irreplaceable role in transmitting genetic information from one generation to the next, and also play an important role in sex differentiation in poultry, while little is known about epigenetic factors that regulate germ cell differentiation. In this study, RNA-seq was used to detect the expression profiles of long non-coding RNAs (lncRNAs) during the differentiation of chicken embryonic stem cells (ESCs) into spermatogonial stem cells (SSCs). The results showed that a total of 296, 280 and 357 differentially expressed lncRNAs (DELs) were screened in ESCs vs. PGCs, ESCs vs. SSCs and PGCs vs. SSCs, respectively. Gene Ontology (GO) and KEGG enrichment analysis showed that DELs in the three cell groups were mainly enriched in autophagy, Wnt/β-catenin, TGF-β, Notch and ErbB and signaling pathways. The co-expression network of 37 candidate DELs and their target genes enriched in the biological function of germ cell development showed that XLOC_612026, XLOC_612029, XLOC_240662, XLOC_362463, XLOC_023952, XLOC_674549, XLOC_160716, ALDBGALG0000001810, ALDBGALG0000002986, XLOC_657380674549, XLOC_022100 and XLOC_657380 were the key lncRNAs in the process of male germ cell formation and, moreover, the function of these DELs may be related to the interaction of their target genes. Our findings preliminarily excavated the key lncRNAs and signaling pathways in the process of male chicken germ cell formation, which could be helpful to construct the gene regulatory network of germ cell development, and also provide new ideas for further optimizing the induction efficiency of germ cells in vitro.