circGAB1 Activates Autophagy to Promote Sepsis-Associated Acute Kidney Injury by Interacting with ELAVL1 to Activate the HMGB3/β-catenin Signaling Pathway​.

METTL3/FOSL1-associated inflammatory and autophagy-related responses involve m6A-related regulation in sepsis-induced acute kidney injury.

BACKGROUND Sepsis-induced acute kidney injury (S-AKI) is marked by tubular damage, inflammation, and dysregulated autophagy. N6-methyladenosine (m6A) RNA modification has emerged as an important regulator of mRNA stability and cellular stress responses; however, its involvement and related regulatory mechanisms in S-AKI remain incompletely understood. METHODS Human HK-2 proximal tubular epithelial cells were stimulated with LPS to establish an in vitro S-AKI model, while CLP-induced septic C57BL/6J mice were used as an in vivo model. Global m6A levels, METTL3, and FOSL1 expression were assessed by ELISA, qRT-PCR, and Western blot. Functional roles of METTL3 and FOSL1 were evaluated using siRNA-mediated knockdown, plasmid-driven overexpression, and pharmacological inhibitors. MeRIP-qPCR and RIP-qPCR were performed to evaluate m6A-related enrichment and the association between METTL3 and FOSL1 mRNA. Inflammatory cytokines, autophagy-related markers, NF-κB and mTOR signaling alterations, renal function, and histopathological changes were assessed. RESULTS LPS stimulation increased global m6A levels and upregulated METTL3 and FOSL1 expression in HK-2 cells, accompanied by enhanced inflammatory responses and autophagy-related alterations. FOSL1 knockdown attenuated LPS-induced inflammation and autophagy-related changes, whereas METTL3 overexpression increased FOSL1 expression and exacerbated these effects. Further analyses indicated that METTL3 was associated with FOSL1 mRNA stability in an m6A-related manner. Alterations in FOSL1 expression were associated with changes in NF-κB and mTOR-related signaling responses under S-AKI conditions. In CLP-induced S-AKI mice, METTL3 knockdown reduced FOSL1 expression, alleviated inflammatory responses and autophagy-related alterations, and improved renal function and histopathological injury. CONCLUSION Our findings suggest that METTL3/FOSL1-associated regulatory responses may participate in S-AKI through m6A-related regulation, contributing to inflammatory and autophagy-related alterations. These findings provide further insight into the involvement of m6A-related regulation in the pathogenesis of S-AKI.

The NF-κB/miR-378c/IRG1 axis drives tubular injury in septic AKI by suppressing immunometabolic protection

Septic acute kidney injury (AKI) is a life-threatening complication with high morbidity and mortality. Despite decades of research, therapeutic options remain limited to supportive care, underscoring the urgent need to decipher the molecular drivers that govern septic AKI. We used a murine LPS-induced septic AKI model and cultured BUMPT cells. miR-378c expression was assessed by qPCR and fluorescence in situ hybridization. Gain- and loss-of-function studies were performed using miR-378c mimics or locked nucleic acid (LNA) inhibitors in vivo and immune-responsive gene 1 (IRG1) overexpression in vitro. Molecular mechanisms were investigated via chromatin immunoprecipitation (ChIP), luciferase reporter assays, western blotting, and immunofluorescence. miR-378c was significantly upregulated in renal proximal tubules after LPS challenge. NF-κB p65 directly bound to the miR-378c host gene promoter and drove its transcription, confirmed by ChIP and NF-κB inhibition with TPCA-1. Overexpression of miR-378c exacerbated kidney dysfunction, tubular apoptosis, and inflammation, while its inhibition conferred protection. IRG1, encoding the immunomodulatory enzyme that produces itaconate, was identified as a direct target of miR-378c. miR-378c suppressed IRG1 expression, and IRG1 overexpression alone reduced LPS-induced apoptosis and proinflammatory cytokine production (IL-1β, IL-6, TNF-α). We define a maladaptive NF-κB/miR-378c/IRG1 axis in septic AKI, where inflammation-induced miR-378c silences a key metabolic protector in tubular cells. Targeting this pathway represents a promising therapeutic strategy to preserve renal function during sepsis.

Mir452 protects against septic acute kidney injury by targeting Apaf1 to relieve CASP9-mediated suppression of autophagy.

Septic acute kidney injury (AKI) is associated with high mortality and currently lacks effective therapeutics. Mir452 (microRNA 452) is a newly identified, highly sensitive biomarker for septic AKI, but the biological function of Mir452 was unknown. Here we report that Mir452 protects kidney tubular cells in septic AKI by repressing APAF1 (apoptotic peptidase activating factor 1) and associated caspase activation to preserve macroautophagy/autophagy. Using mouse and cell models of septic AKI induced by lipopolysaccharide (LPS), we found that inhibition of Mir452 exacerbated renal dysfunction, tubular apoptosis, and inflammatory responses, whereas Mir452 mimics significantly attenuated kidney injury. Mechanistically, Mir452 was shown to directly bind to the 3' untranslated region (3'UTR) of Apaf1 mRNA, repressing APAF1 expression and thereby inhibiting apoptosome-mediated CASP9 activation. This repression further alleviated caspase-mediated cleavage of autophagy-related proteins like BECN1 and ATG5, leading to the preservation of autophagic flux, which in turn limits inflammasome activation and inflammation. Notably, tubule-specific deletion of Apaf1 recapitulated the protective effects of Mir452, whereas forced Apaf1 expression aggravated injury, an effect reversed by CASP9 knockdown. Furthermore, Mir452 significantly promotes protective autophagy in septic AKI by suppressing the APAF1-CASP9 axis, as evidenced by upregulated ATG5 and BECN1 expression, enhanced LC3-II accumulation and autophagosome-lysosome fusion, along with reduced SQSTM1/p62 levels. Functional rescue experiments demonstrated that Mir452's anti-inflammatory effects depend entirely on activated autophagy, as overexpression fails when autophagy is inhibited. Together, the results unveil the Mir452-APAF1-CASP9-autophagy signaling axis that provides an intrinsic anti-inflammation and anti-apoptosis mechanism, suggesting new therapeutic targets for septic AKI.

Regulation of acute myocardial infarction by CircTMCC1 through mitochondrial dysfunction and AMPK/mTOR-driven M1 macrophage polarization: role in QFR assessment.

Circular RNAs (circRNAs) have been implicated in various cardiovascular diseases and hold promise as diagnostic biomarkers and therapeutic targets. However, the roles and mechanisms of circRNAs in coronary artery disease (CAD) and its severe complication, acute myocardial infarction (AMI), remain unclear. CircRNA sequencing, fluorescence in situ hybridization, and quantitative PCR were used to assess circTMCC1 expression in human coronary artery segments, peripheral blood mononuclear cells (PBMCs) from CAD patients, M1 macrophages, and an AMI mouse model. Multiple analytical methods were employed to investigate the predictive value of circTMCC1 for quantitative flow ratio (QFR) measurements. In vitro, we employed plasmid overexpression, small interfering RNA transfection, flow cytometry, immunofluorescence, reactive oxygen species (ROS), and mitochondrial membrane potential assays. In vivo, Masson's trichrome, hematoxylin and eosin staining, and immunohistochemistry were performed. Mechanistic investigations included bioinformatics, RNA pull-down, RNA immunoprecipitation, co-immunoprecipitation, western blotting, and immunofluorescence. CircTMCC1 was significantly upregulated in CAD patients (p < 0.001) and associated with poor prognosis in AMI mouse models. CircTMCC1 was highly expressed in M1 macrophages (p < 0.001), and silencing its expression reduced M1 polarization, improved cardiac function after infarction, and regulated mitochondrial autophagy. Mechanistically, circTMCC1 facilitates the interaction between annexin A1 and the E3 ligase TRIM38, leading to annexin A1 degradation. Additionally, the AMPK/mTOR signaling pathway was identified as a downstream target of circTMCC1. These findings suggest that circTMCC1 may serve as a promising diagnostic biomarker and therapeutic target for CAD and AMI, potentially improving prognosis.

LncRNA DLX6-AS1 promotes necroptosis through PI3K/AKT/mTOR signaling pathway in myocardial ischemia/reperfusion injury mice

Myocardial ischemia/reperfusion injury (MIRI) leads to life-threatening myocardial infarction. Necroptosis is involved in MIRI. The lncRNA DLX6-AS1 was found to participate in the context of MIRI. In this article, we examined the effect of DLX6-AS1 on ischemia perfusion-induced myocardial injury caused by necroptosis and the underlying potential mechanism. We constructed a mouse model of MIRI, and hematoxylin-eosin staining, TUNEL staining, echocardiology, Western blotting (WB), and reverse transcriptase-polymerase chain reaction (RT‒PCR) were employed to evaluate myocardial infarction and necroptosis. Rat H9c2 cells were induced by hypoxia-reoxygenation (H/R), and we analyzed the possible mechanism by overexpressing and inhibiting DLX6-AS1 expression. Cell Counting Kit 8, lactate dehydrogenase (LDH), flow cytometry, RT‒PCR, and WB were utilized to examine cell injury, apoptosis, and relative protein expression. MIRI induced myocardial damage and impaired cardiac function in mice. Ischemia/reperfusion injury results in necroptosis, a process that Nec-1 inhibits. The mRNA levels of RIP1, RIP3, and MLKL were increased, and DLX6-AS1 demonstrated an increase in the IR model, indicating that DLX6-AS1 was associated with necroptosis. Furthermore, H/R-induced H9C2 cells exhibited high LDH levels, low cell activity, and severe apoptosis levels. DLX6-AS1 overexpression caused cell damage and necroptosis and increased the expression of proteins, including PI3K, p-PI3K, AKT, p-AKT, mTOR and p-mTOR. DLX6-AS1 inhibition suppressed necroptosis and cell damage through the PI3K/AKT/mTOR signaling pathway. Myocardial ischemia‒reperfusion injury induces necroptosis, and DLX6-AS1 promotes this process through the PI3K/AKT/mTOR signaling pathway.

Salidroside alleviates sepsis-associated acute lung injury through modulation of the ERK/FoxO3a signaling axis and improvement of impaired autophagic flux