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:The odontoblasts are specialized cells responsible for dentin synthesis and nociceptive signal detection in response to external stimuli. Recent studies have shown that the mechanosensitive ion channel PIEZO1 is involved in bone formation and remodeling through the influx of calcium ions, and it is abundantly expressed in odontoblasts. However, the specific role of PIEZO1 in reactionary dentinogenesis by odontoblasts and the underlying mechanisms still remain elusive. In this study, we found intense PIEZO1 expression in the plasma membrane and cytoplasm of odontoblasts in human and mouse mandibular molars, and human odontoblast-like cells (hOBLCs). In hOBLCs, PIEZO1 positively regulated DSPP, DMP1, and COL1A1 expression through the Ca2+/PI3K-Akt/SEMA3A signaling pathway. Additionally, exogenous SEMA3A supplementation effectively reversed reduced mineralization capacity in PIEZO1-knockdown hOBLCs. In vivo, Piezo1 expression peaked at day 7 and returned to baseline at day 21 in a wild-type (WT) mice dentin injury model, with Sema3a presenting a similar expression pattern. To investigate the specific role of PIEZO1 in reactionary dentinogenesis, mice with a conditional knockout of PIEZO1 in odontoblasts were generated, and no significant differences of teeth phenotypes were observed between the control and conditional knockout (cKO) mice. Nevertheless, cKO mice exhibited reduced reactionary dentin formation, and decreased Sema3a and Dsp positive staining after dentin injury, indicating impaired dental pulp repair mediated by odontoblasts. In summary, these findings suggest that PIEZO1 enhances mineralization capacity of hOBLCs in vitro via the Ca2+/Akt/SEMA3A signaling pathway and contributes to dental pulp repair through enhancing reactionary dentinogenesis in vivo.
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:In previous studies, we found that high expression of aldehyde dehydrogenase 1 family member A3 (ALDH1A3) was associated with more lymph node metastases in pancreatic ductal adenocarcinoma (PDAC). We here report in PDAC Aldh1a3 promotes lung colonization, while is dispensable in liver colonization or proliferation. Aldh1a3 upregulates the transcription of Plxnb1 and Nrp1 via accelerating acetylation at histone H3 lysine in the promoter regions of Plxnb1 and Nrp1. The enhancing signaling of Sema4d-Plxnb1 and Sema3a-Nrp1 between pancreatic cancer cells and lung epithelial cells facilitate tumor cells to colonize in the lung. Our studies have uncovered Aldh1a3 as a key regulator of semaphorin signaling. Sema4d-Plxnb1 and Sema3a-Nrp1 signaling is important for lung metastatic organotropism of PDAC, but is dispensable in liver metastasis.
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:Renal hypoxia is widespread in acute kidney injury (AKI) of various aetiologies. Hypoxia adaptation, conferred through the hypoxia-inducible factor (HIF), appears to be insufficient. Here we show that HIF activation in renal tubules through Pax8-rtTA-based inducible knockout of von Hippel-Lindau protein (VHL-KO) protects from rhabdomyolysis-induced AKI. In this model, histological observations indicate that injury mainly affects proximal convoluted tubules, with 5% necrosis at d1 and 40% necrosis at d2. HIF-1alpha up-regulation in distal tubules reflects renal hypoxia. However, lack of HIF in proximal tubules suggests insufficient adaptation by HIF. AKI in VHL-KO mice leads to prominent HIF activation in all nephron segments, as well as to reduced serum creatinine, serum urea, tubular necrosis, and apoptosis marker caspase-3 protein. At d1 after rhabdomyolysis, when tubular injury is potentially reversible, HIF mediated protection in AKI is associated with activated glycolysis, cellular glucose uptake and utilization, autophagy, vasodilation, and proton removal as demonstrated by qPCR, pathway enrichment analysis and immunohistochemistry. Together, our data provide evidence for a HIF-orchestrated multi-level shift towards glycolysis as a major mechanism for protection against acute tubular injury. All experiments were carried out in transgenic mice in which selective renal tubular VHL knockout (VHL-KO) was inducible by doxycycline (Reference: Mathia S, Paliege A, Koesters R, Peters H, Neumayer HH, Bachmann S, Rosenberger C. Action of hypoxia-inducible factor in liver and kidney from mice with Pax8-rtTA-based deletion of von Hippel-Lindau protein. Acta Physiol (Oxf). 2013; 207(3):565-76.). Four groups of animals were used: 1) controls: untreated mice; 2) VHL-KO: injected with doxycycline (0.1 mg per 10 g body weight SC), 4 days prior to sacrifice; 3) AKI: rhabdomyolysis; 4) VHL-KO/AKI: doxycycline plus rhabdomyolysis. To induce AKI, 50% glycerol (0.05 ml per 10 g body weight) was injected IM into the left hind limb under isoflurane narcosis. Drinking water was withdrawn between 20 h prior and 24 h after glycerol injection.
Project description:Farnesoid X receptor (FXR, also known as NR1H4) is crucial to nephroprotective in several kinds of kidney diseases, including obesity, diabetes, aging, acute kidney injury and chronic kidney disease. FXR plays a key role in maintaining cholesterol and bile acid levels and is highly expressed in the liver, intestine and kidneys. In kidney diseases, it is reported that FXR has anti-lipogenic, anti‐inflammatory, antifibrotic, and antioxidant functions. Here, using genomics analysis, we investigated whether FXR attenuates cisplatin-induced AKI through the regulation of ferroptosis. The increased blood urea nitrogen, serum creatinine and ferroptotic responses in cisplatin-induced AKI mice were attenuated by treatment with FXR agonist, GW4064, while those were exacerbated in FXR knockout mice. Using RNA-sequencing analysis, we found novel target genes for FXR associated with ferroptosis. FXR agonist treatment increases lipid and glutathione metabolic gene expression and decreases cell death genes expression. This study identifies transcriptional regulation of ferroptosis by FXR as a potential therapeutic target for cisplatin-induced AKI.