Project description:We have employed whole genome microarray expression profiling as a discovery platform to identify genes with the potential to distinguish between the mice with renal IRI injury and sham-operated group.Expression of Gpr97 from this signature was quantified in the same kind of samples by real-time PCR, confirming the change pattern. By microarray analysis, we found that IR-induced Sema3A expression was significantly abolished by Gpr97 deficiency in mice
Project description:Background G protein-coupled receptors (GPCRs) participate in a variety of physiologic functions, and several GPCRs have critical physiologic and pathophysiologic roles in the regulation of renal function. We investigated the role of Gpr97, a newly identified member of the adhesion GPCR family, in AKI.Methods AKI was induced by ischemia-reperfusion or cisplatin treatment in Gpr97-deficient mice. We assessed renal injury in these models and in patients with acute tubular necrosis by histologic examination, and we conducted microarray analysis and in vitro assays to determine the molecular mechanisms of Gpr97 function.Results Gpr97 was upregulated in the kidneys from mice with AKI and patients with biopsy-proven acute tubular necrosis compared with healthy controls. In AKI models, Gpr97-deficient mice had significantly less renal injury and inflammation than wild-type mice. Gpr97 deficiency also attenuated the AKI-induced expression of semaphorin 3A (Sema3A), a potential early diagnostic biomarker of renal injury. In NRK-52E cells subjected to oxygen-glucose deprivation, siRNA-mediated knockdown of Gpr97 further increased the expression of survivin and phosphorylated STAT3 and reduced toll-like receptor 4 expression. Cotreatment with recombinant murine Sema3A protein counteracted these effects. Finally, additional in vivo and in vitro studies, including electrophoretic mobility shift assays and luciferase reporter assays, showed that Gpr97 deficiency attenuates ischemia-reperfusion-induced expression of the RNA-binding protein human antigen R, which post-transcriptionally regulates Sema3A expression.Conclusions Gpr97 is an important mediator of AKI, and pharmacologic targeting of Gpr97-mediated Sema3A signaling at multiple levels may provide a novel approach for the treatment of AKI.
Project description:Acute kidney injury (AKI) is a critical public health concern with high morbidity and mortality.Using male mice and HK-2 cells, we found that the NAD⁺ precursor NMN restored renal NAD⁺ levels and activated SIRT1, markedly lowering plasma creatinine and BUN, reducing NGAL and KIM-1 expression, suppressing IL-6/IL-18 and neutrophil infiltration, and attenuating ROS and LDH release. Thus, NMN protects against CIS-AKI via the NAD⁺–SIRT1 pathway and represents a promising therapeutic strategy.
Project description:Interstitial renal inflammation contributes to the transition from acute kidney injury (AKI) to chronic kidney disease (CKD). Recently, protein lactylation modification has emerged as a novel mechanism mediating chronic organ damage. We investigated lactylated protein profiles and the role of protein lactylation during AKI progression. Severe and moderate AKI mouse models were constructed by bilateral renal ischemia for 35 and 25 min respectively. The lactylation enhancer and inhibitors were used to verify the effect of protein lactylation. Lactylated proteomics was used to detect lactylated protein changes in kidneys, and the lactylated proteins related to kidney injury were screened for verification. We observed significantly higher lactate and protein lactylation levels in the severe than in the moderate AKI model 1–28 days post-injury. Inhibition of protein lactylation protected against renal interstitial fibrosis. In vitro and in vivo experiments demonstrated that protein lactylation activated Nod-like receptor protein 3 (NLRP3) inflammasomes, promoting the AKI–CKD transition. Comprehensive lactylome profiling of severe AKI models revealed a role for lactylated proteins in metabolic pathways, primarily the tricarboxylic acid (TCA) cycle where the rate-limiting enzyme, citrate synthase (CS), exhibited significantly elevated lactylation levels 3–7 days post-AKI induction; K370 was the most significant lysine residue. In vitro, following hypoxia/reoxygenation, the modified/lactylated K370T group significantly decreased CS activity and mitochondrial function. Furthermore, CS-K370 lactylation activated the NLRP3 inflammasome. Lactylation of CS promotes the AKI–CKD transition through NLRP3 inflammasome activation. Inhibition of CS lactylation shows therapeutic potential for preventing this transition.
Project description:Kidney repair after acute kidney injury (AKI) relies on a well-regulated extracellular matrix (ECM) that provides structural and mechanical cues. Fibroblasts and pericytes, key ECM producers, are rapidly activated post-injury, but ECM-driven repair mechanisms remain unclear. Using proteomics, spatial transcriptomics, and animal models, we profiled the landscape of matrix proteins altered post-AKI, highlighting microfibrillar-associated protein 2 (Mfap2) as a critical ECM component. Predominantly derived from fibroblasts and pericytes, Mfap2 loss impairs kidney architecture and metabolism, worsening AKI. Proteomics revealed that Mfap2 knockout suppresses tubule-derived Hmgcs2 via Esr2-mediated transcriptional repression and enhanced succinylation. Phosphoproteomics showed Mfap2 deletion hyperactivates MAPK and Lats1 in tubules, independent of integrin signaling and Yap/Taz. Mechanistically, reduced Lats1 boosts Esr2 transcription without affecting its degradation. Esr2 agonists restored kidney function in Mfap2-deficient models. Thus, Mfap2 governs ECM stiffness, transduces mechanical signals, reprograms metabolism, and fosters a pro-repair microenvironment critical for AKI recovery.