The FASEB Journal最新文献

Exosomes originate from multivesicular bodies formed by the invagination of intracellular lysosomal particles and constitute endogenous extracellular vesicles. When the microenvironment of an organism undergoes changes, exosomes sort different proteins, lipids, and nucleic acids. This selective packaging allows them to target and localize in recipient cells, thereby influencing or modulating cellular behavior. In aquatic organisms, exosomes play a crucial role as mediators of cellular communication, participating in vital processes such as immune regulation and growth and development. This paper aims to review the biogenesis and contents of exosomes, introduces commonly employed methods for their separation and identification, and discusses recent applications of exosomes in aquatic organisms and therefore provides a valuable reference for further research on exosomes within this group of organisms.

Tenascin-X (TNXB) is an extracellular matrix glycoprotein known for its structural and regulatory roles in connective tissues, yet its pathophysiological role in testicular development and spermatogenesis remains uncharacterized. Here, we identified TNXB as clinically implicated in human spermatogenic disorder, with a significant downregulation in the testes of patients with non-obstructive azoospermia (NOA) revealed by isobaric tags for relative and absolute quantification (iTRAQ)-based proteomics. Developmental profiling in mice revealed a progressive increase in TNXB expression with testicular maturation, with strong localization in germ cells. To elucidate its function in spermatogenesis, we generated conditional knockout (cKO) mice with germ cell-specific deletion of the Tnxb gene by using the Cre-LoxP system (Ddx4-Cre⁺, Tnxb^LoxP/Null). Tnxb deficiency led to reduced testis size, severe tubular degeneration, excessive germ cell loss, impaired spermatogenesis, and decreased sperm count and motility. Transcriptomic profiling of cKO testes revealed that dysregulated genes were mainly associated with meiosis and germ cell development, cytoskeletal and tight junction organization, and cell junction assembly, which were validated by quantitative real-time PCR, western blotting, and immunofluorescence. Further investigation demonstrated mislocalization and altered expression of key proteins regulating the cytoskeleton, cell junction, and extracellular matrix organization in the cKO testes. Notably, TNXB demonstrated an interaction with Collagen IV, a crucial extracellular matrix component. Deficiency of Tnxb led to an abnormal association between the Sertoli cell cytoskeleton and the junctional structure. These findings confirm that TNXB is indispensable for preserving the integrity and interactions among the extracellular matrix, cytoskeleton, and cell junction within the testis, and its deficiency impairs testicular architecture and spermatogenesis.

Elevated circulating low-density lipoprotein cholesterol (LDL-C) is a key risk factor for coronary artery disease (CAD). The pathogenesis of CAD is multifactorial, driven by heritable and lifestyle-related risk factors. Although CD4⁺ T cells are one of the main cell types in atherosclerotic lesions, their interaction with atherogenic oxidized LDL (ox-LDL) remains poorly understood. Therefore, we sought to characterize the transcriptomic and epigenomic consequences of ox-LDL on activated human CD4⁺ T cells. We find that ox-LDL causes a shift towards a pro-inflammatory, cytokine-producing CD4⁺ T cell transcriptomic state. Concurrently, ox-LDL induces genome-wide changes in chromatin accessibility, notably in promoter regions. By integrating our multiomic data, we identify the NRF1 and SP1 transcription factors as likely mediators of ox-LDL-induced changes in gene expression. In contrast, the influence of AP-1 related factors over CD4⁺ T cell gene expression decreases following ox-LDL stimulation. We leveraged our multiomic data to investigate the disease relevance of ox-LDL exposure, by investigating genomic locations where CAD-associated single nucleotide polymorphisms were found within dynamic ox-LDL-regulated accessible chromatin regions. Together, we demonstrate a disease-relevant role for ox-LDL in atherogenic conditioning of CD4⁺ T cells. Understanding such cell-type specific interactions with CAD risk factors may facilitate the development of targeted therapies for CAD.

Loss of function G-protein coupled receptor 75 (GPR75) variants in humans are associated with leanness, and Gpr75 null mice are protected from diet-induced obesity (DIO). However, the mechanisms underlying this protection are largely unknown. Here, we investigated the contribution of adipocyte-derived Gpr75 to DIO. Adipocyte-specific Gpr75 knockout (adipo-Gpr75^−/−) male and female mice and their wild-type (WT) littermates were placed on a high-fat diet (HFD) for 14 weeks. Metabolic parameters including body weight, energy intake and expenditure, activity, and glucose metabolism were monitored before and after diet feeding. While WT mice obtained a diabetogenic phenotype on HFD, the adipo-Gpr75^−/− counterparts were protected. This protection showed sexual dimorphism. Female adipo-Gpr75^−/− mice displayed a 50% (p < 0.001) decrease in weight gain and adiposity compared to WT, whereas male adipo-Gpr75^−/− gained weight like WT mice. Interestingly, both male and female adipo-Gpr75^−/− mice exhibited improved glucose handling compared to WT, which was correlated to decreased adiposity, abrogated adipose tissue inflammation, and increased insulin sensitivity in skeletal muscle. Importantly, no differences in food intake were observed; however, adipo-Gpr75^−/− mice exhibited increased activity and energy expenditure, regardless of sex. Taken together, these findings demonstrate that deletion of GPR75 specifically in adipocytes is sufficient to confer protection against DIO and suggest that adipocyte-derived GPR75 contributes importantly to the pathogenesis of DIO potentially by mechanisms that may include promotion of inflammation, impairment of insulin signaling, and disruption of metabolic homeostasis.

Cisplatin-induced ototoxicity is a detrimental side effect of chemotherapy leading to hearing loss, for which no treatments are currently available. Despite the growing recognition of the endocannabinoid (eCB) system (ECS) as a significant contributor to different physiological and pathological processes, its role in hearing remains poorly investigated. To fill this knowledge gap, we performed a molecular profiling of the ECS in auditory hair cell (HC)-like UB/OC1 cells derived from the mouse organ of Corti (OC), demonstrating the presence of the main eCBs-binding receptors and metabolic enzymes along with the major eCBs (N-arachidonoylethanolamine, AEA, and 2-arachidonoylglycerol, 2-AG) and additional eCB-like compounds. Subsequently, we established an in vitro model of cisplatin-induced ototoxicity, which was characterized by the downregulation of the HC marker myosin 7a (Myo 7a), and activation of nuclear factor kappa-light-chain-enhancer of activated B-cells (NF-κB) associated with caspase-3-mediated cell death. In this model, we observed a downregulation of cannabinoid receptor 2 (CB₂R), diacylglycerol lipase β (DAGLβ), and α/β hydrolase domain-containing protein 6 (ABHD6), indicating a perturbation of the 2-AG metabolic pathway. Furthermore, we validated the observed in vitro alterations in the OC of an in vivo model of cisplatin-induced ototoxicity, thereby strengthening the physiological relevance of our findings. Finally, we demonstrated that pharmacological blockade of CB₂R through SR144528 mitigates cisplatin-induced HC damage via inhibition of caspase-3 cleavage in UB/OC1 HC-like cells, thereby providing novel mechanistic insights into the role of CB₂R in ototoxicity. Overall, our study demonstrates the involvement of selective elements of the ECS in cisplatin-induced ototoxicity, hence identifying novel potential biomolecular targets for chemotherapy-related side effects.