FASEB bioAdvances最新文献

Emerging evidence highlights the pivotal role of the gut microbiota (GM) in regulating host metabolism and contributing to the development of insulin resistance (IR). Gut dysbiosis alters the production of critical metabolites, including short-chain fatty acids (SCFAs), bile acids, indole derivatives, and trimethylamine N-oxide (TMAO), which influence intestinal barrier integrity, inflammatory pathways, and glucose homeostasis. Recent clinical and translational studies indicate that SCFAs can improve fasting insulin and HOMA-IR, although the magnitude of benefit varies substantially across individuals, highlighting ongoing controversy surrounding their metabolic effects. Altered microbial regulation of bile-acid metabolism has also been implicated in impaired lipid and glucose signaling, reinforcing the relevance of FXR- and TGR5-mediated pathways in IR. Elevated TMAO levels have further been associated with adverse metabolic outcomes, though debate persists regarding its causal role versus its function as a diet-dependent biomarker. Microbiota-targeted strategies, including dietary fiber, probiotics, and fecal microbiota transplantation (FMT), show potential to modulate these metabolic pathways, yet clinical results remain inconsistent. This narrative review synthesizes recent mechanistic discoveries and clinical findings on microbiota-derived metabolites in IR, highlights key controversies, and outlines future priorities for translating microbiome science into effective and personalized interventions for metabolic disease prevention and management.

Gut microbes are key regulators of immune homeostasis. Their composition fluctuates over time and between individuals and is also influenced by disease. We and others have reported changes in gut bacterial composition following induction of experimental autoimmune encephalomyelitis (EAE), a well-established model for multiple sclerosis (MS). Specifically, we observed reductions in the abundance of bacteria capable of producing gamma-aminobutyric acid (GABA). Because GABA regulates immune cell function, we genetically engineered a Lactococcus lactis strain to overproduce GABA (P8s-GAD L. lactis) and hypothesized that this strain would have protective activity in EAE. To test this hypothesis, a suspension of P8s-GAD L. lactis was administered by gavage to C57BL/6 Envigo (Env) and Jackson Laboratories (Jax) mice at the time of EAE induction. Controls included mice treated with unmodified L. lactis (P-L. lactis) and mice treated with sterile bacterial medium. P8s-GAD L. lactis was clinically protective in Env mice but not in Jax mice. To understand the lack of protection in Jax mice, we examined the effects of treatments on intestinal micro- and mycobiota using 16S rRNA and IST sequencing, and samples were collected at disease induction, 14 days after, and at the end of the experiment (day 28). We also examined the impact of treatments on the brain, using whole-brain proteomics (day 28). Despite the lack of disease protection, P8s-GAD L. lactis significantly modified the gut microbiome by affecting broad taxonomic composition, as quantified by beta-diversity changes over time, and the CNS protein profile, including an increase in Gabra6 expression, the alpha-6 subunit of the GABA type A (GABA_RA) receptor. These changes, combined with reduced EAE severity observed in Env mice, suggest that GABA-producing bacteria could be considered for the treatment of neuroinflammatory conditions. The study also highlights the importance of controlling the mouse source in probiotic and microbiota research within experimental models of immune-mediated diseases.

Mawdsley L, Eskandari R, Kamar F, et al. “In Vivo Optical Assessment of Cerebral and Skeletal Muscle Microvascular Response to Phenylephrine,” FASEB BioAdvances (2024); 6: 390–399, https://doi.org/10.1096/fba.2024-00063.

In paragraph 2 of Section 2.1: Animal Protocol, the reported dosage for the phenylephrine injections was incorrect. The correct intravenous dosage is 10 μg/mL.

We apologize for this error.

Ischemic cardiomyopathy remains a leading cause of heart failure (HF), yet its molecular mechanisms remain incompletely defined. This study aimed to identify the RNA-binding protein 25(RBM25) as a critical regulator of HF progression through MAP4K4 alternative splicing and p38 MAPK pathway activation. A left anterior descending (LAD) coronary artery ligation-induced HF model was established in Sprague–Dawley (SD) rats, with pericardial delivery of lentiviral vectors for RBM25 overexpression (OE-RBM25) or shRNA-mediated knockdown (sh-RBM25). Quantitative PCR (qPCR) experiments confirmed that overexpression of RBM25 induces exon 16 skipping in MAP4K4. Computational modeling further predicted that the resulting variant enhances binding to MAP3K1 and potentially activates the MAPK pathway. Cardiac function, infarct size, apoptosis, and molecular markers were evaluated via echocardiography, TTC staining, ELISA, qPCR, Western blot, and TUNEL assays. RBM25 overexpression significantly increased myocardial infarction area compared to the HF control group (p < 0.01), while RBM25 knockdown reduced infarct size (p < 0.01). Consistently, RBM25 overexpression upregulated pro-apoptotic markers (Caspase-3, Bax; p < 0.05) and downregulated anti-apoptotic Bcl-2 (p < 0.05), whereas RBM25 inhibition reversed these effects. Mechanistically, RBM25 induced exon 16 skipping in MAP4K4, generating a truncated isoform that activated MAPK signaling, as evidenced by increased phosphorylation of ERK (p < 0.05) and elevated downstream effectors (C-FOS, EGR1, PARP1; p < 0.05). P38 MAPK inhibition (SB203580) attenuated RBM25-mediated myocardial injury, while agonist-induced MAPK activation (Gambogic Amide) abolished the protective effects of RBM25 knockdown. These findings suggest that RBM25 exacerbates HF through MAP4K4 splicing-dependent p38 MAPK activation, highlighting its potential as a therapeutic target for ischemic cardiomyopathy.

Ischemic heart disease is a primary cause of death for men and women in the United States. Recent epidemiologic findings, however, suggest that premenopausal women have inherent protection from many cardiovascular pathologies compared to age-matched men, which is lost with menopause. We and others have documented similar protective signaling in animal models, with females exhibiting protection from ischemic injury that is lost with ovariectomy (OVX). Furthermore, in recent studies, we demonstrated that the loss of alcohol dehydrogenase 5 (ADH5) blocked sex-specific cardioprotection in females, but activation of aldehyde dehydrogenase 2 (ALDH2) provided a rescue. ADH5 and ALDH2 both metabolize formaldehyde to formate, potentially implicating formate in female-specific cardioprotection. Therefore, the objective of this study was to examine a role for formate during ischemic injury in female hearts using wild-type (WT) and ADH5^−/− mice. We also aimed to explore estrogen-dependent effects by using ovariectomized (OVX) WT mice. To assess the protective effects of formate in intact WT and ADH5^−/− female mice, as well as OVX WT female mice, hearts were Langendorff-perfused and subjected to ischemia/reperfusion (I/R) injury. Since formate is used in one-carbon metabolism (OCM), select OCM enzymes were also probed via western blot. Importantly, we found that formate significantly reduced infarct size in intact ADH5^−/− female hearts subjected to I/R injury, but formate was without effect in intact WT female hearts. Additionally, formate failed to reduce I/R injury in OVX WT female hearts, despite OVX WT female hearts exhibiting reduced ADH5 and ALDH2 activity. However, we noted that the expression of certain OCM enzymes was downregulated in OVX WT female hearts versus intact WT females, which may prevent proper formate utilization by OCM in OVX WT female hearts. Furthermore, blockage of formate import into OCM in intact WT female hearts also exacerbated I/R injury. Taken together, our findings support formate utilization by OCM as a key component of cardioprotective signaling in female hearts, with estrogen acting as a potential mediator.

Osteoarthritis (OA), a common degenerative joint disorder, continued to present significant challenges in clinical management due to an incomplete understanding of its pathogenesis. Although the full pathophysiology of OA remained unclear, emerging evidence implicated double-stranded RNA (dsRNA) released from damaged articular chondrocytes in promoting cartilage degeneration via the TLR3–IL-33 signaling axis. Our investigation demonstrated that IL-33 exerted dual pathological effects on chondrocytes: it induced cellular hypertrophy with upregulated osteogenic marker expression and mediated fluid shear stress (FSS)–induced matrix degradation. Notably, age-related chondrocyte was associated with increased IL-33 secretion. In vitro experiments revealed that IL-33 administration significantly promoted chondrocyte hypertrophy and osteogenesis. Consistent with these findings, IL-33-knockout (KO) murine models showed marked resistance to FSS-induced joint damage, with reduced cartilage erosion compared to wild-type counterparts. These mechanistic insights not only advanced the understanding of OA progression but also highlighted IL-33 inhibition as a potential therapeutic strategy. This study provided a solid experimental foundation for the development of novel disease-modifying interventions targeting this pathway.

Liquid–liquid phase separation is a basic biophysical process that creates essential membraneless organelles that support different cellular activities, including chromatin organization and gene expression. The malfunction of liquid–liquid phase separation (LLPS) plays a critical role in numerous diseases, such as neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS) and Alzheimer's disease (AD), which involve TDP-43 and Tau, various cancers that utilize SPOP and YAP/TAZ proteins, and viral infections where pathogens use LLPS to replicate and avoid immune detection. This review brings together the fast-growing knowledge about LLPS across multiple scientific fields. The paper examines the physiological functions of LLPS along with its disease pathogenesis mechanisms and presents various experimental techniques (e.g., advanced microscopy, FRAP, FCS) for its investigation. It introduces new therapeutic approaches such as PTM modulation, small molecules like 1,6-hexanediol and Lipoamide, and advanced genetic tools including CRISPR and PROTACs like PSETAC, which also explores diagnostic applications. The thorough integration of knowledge presented here is essential to connect separate scientific findings while propelling research forward and turning LLPS discoveries into new biomedical developments.

For patients with certain types of malignant tumors, chemotherapy is administered before and/or after surgery. However, the potential impact of chemotherapeutic agents on tissue regeneration and wound healing after surgery is not fully understood. In this study, we examined the possible effects of doxorubicin (DOX), one of the most widely used chemotherapeutic agents, on muscle regeneration using a mouse muscle injury model. Histologic analysis revealed that DOX significantly impairs muscle regeneration, resulting in reduced muscle mass and fibrosis when administered during the early phase of the inflammatory response following injury. Contrary to our initial assumption, DOX administration did not suppress the proliferation of satellite cells or the expression of myogenic transcripts. Rather, DOX delayed the infiltration of immune cells to the injury site, which most likely resulted in insufficient clearance of necrotic tissues and prolonged immune cell infiltration. Taken together, our findings reveal an unrecognized effect of DOX on muscle regeneration and underscore the critical role of the early inflammatory response in initiating proper muscle regeneration after injury.

Atherosclerosis is a chronic vascular disease characterized by the accumulation of cholesterol-rich lipids within the intima of large and medium-sized arteries. It is a leading cause of morbidity and mortality worldwide, contributing to the majority of myocardial infarctions and strokes. Ellagic acid (EA), a naturally occurring polyphenolic compound found in various plant species, exhibits promising potential in enhancing cholesterol metabolism and reducing the risk of atherosclerosis. However, the precise mechanisms and molecular targets underlying EA's cholesterol-regulating effects remain poorly understood. In this study, we demonstrate that EA effectively binds to the epidermal growth factor receptor (EGFR), exhibiting a dissociation constant (Kd) of 4.33 × 10⁻⁷ M and a binding energy of −7.1 kcal/mol. This binding activates EGFR and specifically engages the mitogen-activated protein kinase (MAPK) pathway, leading to the upregulation of low-density lipoprotein receptor (LDLR) expression in HepG2 cells. Furthermore, cetuximab, an EGFR-blocking antibody, inhibits the LDLR upregulation induced by EA, confirming EGFR as a key target in the regulation of LDLR expression. To evaluate the in vivo effects of EA on atherosclerosis, we encapsulated EA within human serum albumin to form nanoparticles (EA-NPs). This approach addresses poor water solubility and its tendency to convert into urolithin derivatives of EA following oral administration. In HepG2 cells, EA-NPs significantly enhanced LDLR expression, accompanied by increased phosphorylation of EGFR and extracellular signal-regulated kinase (ERK). In an ApoE⁻/⁻ mouse model, EA-NPs exhibited potent anti-atherosclerotic effects mediated through the EGFR and MAPK pathways. Additionally, EA-NPs reduced hepatic lipid accumulation and attenuated the formation of aortic plaques. In conclusion, EA and its nanoparticle formulation effectively impede the progression of atherosclerosis, underscoring their therapeutic potential. These findings provide a robust foundation for the development of EA-based strategies as a viable daily therapeutic intervention for atherosclerosis management.

De novo proline synthesis is a highly conserved and essential biochemical pathway in mammals. Beyond serving as a fundamental building block for proteins, proline also plays key roles in diverse cellular functions and maintaining tissue homeostasis. Over the past decade, accumulating evidence has underscored the significance of this pathway in regulating critical cellular processes, including redox balance, cell growth, signal transduction, and the synthesis of nucleotides and proteins, as well as overall cellular metabolism. The biosynthesis of proline is tightly controlled by multiple evolutionarily conserved mechanisms to ensure proper cellular function. Importantly, disruptions in proline metabolism—particularly changes in the activity or expression of enzymes involved in its synthesis and degradation—have been implicated in the onset and progression of several diseases, notably cancer and fibrosis. In this review, we highlight recent advances in understanding the regulation of de novo proline synthesis. We also examine how dysregulation of this pathway contributes to disease development and influences therapeutic outcomes. Finally, we explore the therapeutic potential of targeting proline metabolism in disease treatment.