Objective: Effects of the diet-induced gut microbiota dysbiosis reach far beyond the gut. We aim to uncover the direct evidence involving the gut–testis axis in the aetiology of impaired spermatogenesis. Design: An excessive-energy diet-induced metabolic syndrome (MetS) sheep model was established. The testicular samples, host metabolomes and gut microbiome were analysed. Faecal microbiota transplantation (FMT) confirmed the linkage between gut microbiota and spermatogenesis. Results: We demonstrated that the number of arrested spermatogonia was markedly elevated by using 10× single-cell RNA-seq in the MetS model. Furthermore, through using metabolomics profiling and 16S rDNA-seq, we discovered that the absorption of vitamin A in the gut was abolished due to a notable reduction of bile acid levels, which was significantly associated with reduced abundance of Ruminococcaceae_NK4A214_group . Notably, the abnormal metabolic effects of vitamin A were transferable to the testicular cells through the circulating blood, which contributed to abnormal spermatogenesis, as confirmed by FMT. Conclusion: These findings define a starting point for linking the testicular function and regulation of gut microbiota via host metabolomes and will be of potential value for the treatment of male infertility in MetS.

Controlled mRNA storage and stability is essential for oocyte meiosis and early embryonic development. However, how to regulate mRNA storage and stability in mammalian oogenesis remains elusive. Here we showed that LSM14B, a component of membraneless compartments including P-body-like granules and mitochondria-associated ribonucleoprotein domain (MARDO) in germ cell, is indispensable for female fertility. To reveal loss of LSM14B disrupted primordial follicle assembly and caused mRNA reduction in non-growing oocytes, which was concomitant with the impaired assembly of P-body-like granules. 10× Genomics single-cell RNA-sequencing and immunostaining were performed. Meanwhile, we conducted RNA-seq analysis of GV-stage oocytes and found that Lsm14b deficiency not only impaired the maternal mRNA accumulation but also disrupted the translation in fully grown oocytes, which was closely associated with dissolution of MARDO components. Moreover, Lsm14b-deficient oocytes reassembled a pronucleus containing decondensed chromatin after extrusion of the first polar body, through compromising the activation of maturation promoting factor, while the defects were restored via WEE1/2 inhibitor. Together, our findings reveal that Lsm14b plays a pivotal role in mammalian oogenesis by specifically controlling of oocyte mRNA storage and stability.

The mediation of maternal-embryonic cross-talk via nutrition and metabolism impacts greatly on offspring health. However, the underlying key interfaces remain elusive. Here, we determined that maternal high-fat diet during pregnancy in mice impaired preservation of the ovarian primordial follicle pool in female offspring, which was concomitant with mitochondrial dysfunction of germ cells. Furthermore, this occurred through a reduction in maternal gut microbiota-related vitamin B1 while the defects were restored via vitamin B1 supplementation. Intriguingly, vitamin B1 promoted acetyl-CoA metabolism in offspring ovaries, contributing to histone acetylation and chromatin accessibility at the promoters of cell cycle-related genes, enhancement of mitochondrial function, and improvement of granulosa cell proliferation. In humans, vitamin B1 is downregulated in the serum of women with gestational diabetes mellitus. In this work, these findings uncover the role of the non-gamete transmission of maternal high-fat diet in influencing offspring oogenic fate. Vitamin B1 could be a promising therapeutic approach for protecting offspring health.

Background: Men with prediabetes often exhibit concomitant low-quality sperm production or even infertility, problems which urgently require improved therapeutic options. In this study, we have established a sheep model of diet-induced prediabetes that is associated with spermatogenic defects and have explored the possible underlying metabolic causes.Results: We compared male sheep fed a normal diet with those in which prediabetes was induced by a rich diet and with a third group in which the rich diet was supplemented by melatonin. Only the rich diet group had symptoms of prediabetes, and in these sheep, we found impaired spermatogenesis characterized by a block in the development of round spermatids and an increased quantity of testicular apoptotic cells. Comparing the gut microbiomes and intestinal digest metabolomes of the three groups revealed a distinctive difference in the taxonomic composition of the microbiota in prediabetic sheep, and an altered metabolome, whose most significant feature was altered sphingosine metabolism; elevated sphingosine was also found in blood and testes. Administration of melatonin alleviated the symptoms of prediabetes, including those of impaired spermatogenesis, while restoring a more normal microbiota and metabolic levels of sphingosine. Fecal microbiota transplantation from prediabetic sheep induced elevated sphingosine levels and impaired spermatogenesis in recipient mice, indicating a causal role of gut microbiota in these phenotypes.Conclusions: Our results point to a key role of sphingosine in the disruption of spermatogenesis in prediabetic sheep and suggest it could be a useful disease marker; furthermore, melatonin represents a potential prebiotic agent for the treatment of male infertility caused by prediabetes.

Parkinson’s disease (PD), a neurodegenerative disorder caused by complex factors, is usually associated to mitochondrial dysfunctions but the links between such disorder and PD remain object of research. Here, we report that impaired mitochondrial quality control (MQC) system is a molecular basis of the mitochondrial dysfunction in PD and that tricarboxylic acid cycle (TCA cycle) disorder is the main feature of such mitochondrial dysfunction. Multi-omics analysis revealed that MDH2, OGDHL and IDH3G enzymes are bottlenecks in the enzymatic reactions of the TCA cycle in PD. Mechanistically, the abnormal α-KG/fumarate ratio caused by the TCA cycle bottleneck inhibits histone H3K4me3 demethylation and further enhances the expression of alpha-synuclein (SNCA), which may promote PD at an early stage. On these bases, we proposed a number of PD therapeutic strategies targeting mitochondria and histone methylation modifications, which proved to be effective in in vitro or in vivo models, especially citrate supplementation, in restoring normal TCA cycle enzymatic reactions. Taken together, our work highlights the non-negligible regulatory role of “mitochondrial-nuclear” communication in PD and provides important insights for the development of PD therapeutic strategies.

Mounting evidence underscores that high-concentrate diets (HCD) significantly impair male reproductive health, leading to infertility, and are closely associated with dysregulation of the gut microbiome and metabolome. However, effective therapeutic strategies targeting these alterations remain elusive. Notably, compelling evidence implicates the gut-testis axis as a critical mediator in the etiology of poor semen quality. Gut-derived metabolites, as key players in the gut-testis axis, warrant in-depth investigation as potential therapeutic targets for addressing male infertility caused by environmental factors, particularly dietary stressors. In this study, through an integrated multi-omics approach employing 10× Genomics single-cell mRNA sequencing, 16S ribosomal DNA sequencing and metabolomic profiling, we demonstrate that HCD induces DNA damage in Sertoli cells and disrupts the integrity of the blood-testis barrier (BTB), resulting in a significant decline in spermatozoa quality. Moreover, HCD impairs gut microbiota homeostasis and arginine biosynthesis, particularly leading to a remarkable decrease in L-citrulline levels. Additionally, fecal microbiota transplantation (FMT) experiments confirm that gut microbiota dysbiosis contributes to Sertoli cell DNA damage and BTB dysfunction. Interestingly, the effect of HCD-induced aberrant Sertoli cells function can be rescued by supplementation with L-citrulline. Collectively, these findings highlight the therapeutic potential of L-citrulline in protecting male reproductive health under dietary stress conditions, particularly through its action on the gut-testis axis.