Endoplasmic reticulum stress increases exosome biogenesis and packaging relevant to sperm maturation in response to oxidative stress in obese mice

Abstract

Background Mammalian sperm maturation in the epididymis is mainly modulated by exosomes that are secreted into the epididymal lumen from epididymal epithelial cells (EECs). Exposure to oxidative stress (OS) resulting from being fed a high fat diet (HFD) reduces sperm fertility, which is one of the cause inducing male infertility. Thus, we hypothesize that stress-induced changes in exosome content play a critical role in mediating this detrimental process. Methods An obese mouse model was established by feeding a HFD. Then oxidative stress status was measured in the mouse caput epididymis, epididymal fluid and spermatozoa. Meanwhile, epididymis-derived purified exosomes were isolated and validated. Subsequently, liquid chromatography tandem mass spectrometry (LC-MS) was used to perform proteomic analysis of purified exosomes. Gene Ontology (GO) analysis was performed along with pathway enrichment to identify differentially expressed proteins (DEPs). Results Two hundred and two DEPs mostly related to endoplasmic reticulum (ER) function were identified in the exosomes separated from the epididymis of control mice and obese mice. The ER stress and CD63 (an exosome marker), both increased in the caput epididymis of obese mice. Furthermore, an in vitro study showed that palmitic acid (PA), an-oxidative stress inducer, increased exosome biogenesis and secretion in the EECs. Conclusion Oxidative stress in the epididymal microenvironment induces ER stress in the EECs. This effect alters the epididymis-derived exosome content, profile and amounts of their differentially expressed ER proteins. Such changes may affect exosome biogenesis and cargo packaging, finally leading to abnormalities in sperm maturation and fertility.

Effects of a high‐fat diet on rat epididymis

“…These results indicated an increase in oxidative stress and matched the findings of previous studies conducted on HFD rats, indicating that HFD causes cellular oxidative stress in the testis (Latino et al, 2022; Verderame et al, 2018; Migliaccio, Sica et al, 2019; Migliaccio, Gregorio et al, 2019). Exposure to oxidative stress due to the administration of an HFD can reduce sperm fertility in obese mice (Y. Li et al, 2022). Oxidative stress in the epididymal microenvironment can induce stress in the endoplasmic reticulum, altering the epididymis‐derived exosome content, profile, and content of differentially expressed proteins in the endoplasmic reticulum, which can cause abnormalities in sperm maturation and fertility (Y. Li et al, 2022).…”

“…Exposure to oxidative stress due to the administration of an HFD can reduce sperm fertility in obese mice (Y. Li et al, 2022). Oxidative stress in the epididymal microenvironment can induce stress in the endoplasmic reticulum, altering the epididymis‐derived exosome content, profile, and content of differentially expressed proteins in the endoplasmic reticulum, which can cause abnormalities in sperm maturation and fertility (Y. Li et al, 2022).…”

“…In this study, we also found that the expression of the PINK1 protein was lower in the corpus and cauda of rats in the HFD group, which indicated a decrease in mitophagy. Mitophagy is important for maintaining the quality and quantity of the mitochondria, as well as homeostasis; conversely, the inadequate removal of mitochondria leads to the generation of oxidative species, including reactive oxygen species and reactive nitrogen species, which can cause various degenerative diseases (Kitagishi et al, 2017; Y. Li et al, 2022; Shefa et al, 2019). Therefore, we hypothesized that the decrease in mitophagy induced by HFD could contribute to an increase in oxidative stress and impairment in the function of the epididymis.…”

“…Also, processes that are activated and mechanisms that can damage the epididymis are not clear. An increase in oxidative stress in the epididymis of mice fed an HFD was found to induce stress in the endoplasmic reticulum, which altered the profile and the quantity of differentially expressed proteins, leading to abnormalities in sperm maturation and fertility (Y. Li et al, 2022).…”

Oxidative Stress and Male Fertility: Promising Role of Nutraceuticals

“…Obesity change in the epididymis's microenvironment by increasing MDA expression in epididymal fluids with low glutathione levels that impair sperm quality. Epididymosomes secreted in the epididymal lumen communicates with the sperm by sharing the protein and noncoding RNA contents, lowering oxidative stress levels [27].…”