Project description:Aims: Cardiac fibroblasts (CFs) play a crucial role in cardiac remodelling, which is a common cause of heart failure (HF). However, the molecular mechanisms underlying the fibroblast-to-myofibroblast transition remain largely unknown. Foxm1 is well known in various cardiopulmonary pathologies. However, Foxm1-driven CF activation in the progression of cardiac remodelling to HF remains to be investigated. Methods: Changes in Foxm1 expression were assessed in samples from patients with HF and mice with transverse aortic constriction (TAC)-induced cardiac remodelling. Pharmacologic antagonist FDI-6 was used to explore the effects of Foxm1 inhibition on post-TAC outcomes. Tcf21-Cre and PostnMCM were used to evaluate Foxm1 loss- and gain-of-function in CFs and myofibroblasts, respectively. Cardiac function and remodelling were examined by echocardiography and histological analysis. Foxm1 downstream target genes were identified by mass spectrometry (MS) and transcriptomic analysis. Post-translational regulation was evaluated by in vitro chromatin immunoprecipitation, co-immunoprecipitation, and ubiquitination assays. Pharmacological inhibition of Usp10 or knockout of p38γ in vivo verified the signalling pathway by which Foxm1 regulated cardiac remodelling. Results: Foxm1 was upregulated in human HF samples as well as in the mouse cardiac remodelling model. CFs were the primary cell type responsible for Foxm1 upregulation. Foxm1 pharmacological inhibition or genetic knockout in CFs or myofibroblasts significantly attenuated TAC-induced cardiac remodelling and HF. Conversely, conditional overexpression of Foxm1 in CFs or myofibroblasts resulted in more severe pathological cardiac remodelling and dysfunction. Combined RNA-sequencing and MS analysis revealed that Foxm1 promoted Usp10 expression by binding to its promoter. Usp10 interacted with p38γ, resulting in p38γ deubiquitination and thus inﬂuencing the downstream p38 mitogen-activated protein kinase (MAPK) signalling pathway. Pharmacological inhibition of Usp10 or genetic knockout of p38γ ameliorated the exacerbated TAC-induced cardiac remodelling in mice with myofibroblast-specific Foxm1 overexpression. Conclusion: Our findings reveal an essential role of Foxm1 in CF activation during cardiac remodelling. These results suggest that targeting the Foxm1/Usp10/p38γ MAPK axis may represent a new potential therapeutic strategy against pathological cardiac remodelling and HF.

Project description:Purpose:Renal injury with the loss of podocyte was characteristic pathology of diabetic nephropathy (DN) and correlated with increased albuminuria. Many studies have found the nephroprotective effect of the novel inhibitors of sodium-glucose cotransporter 2 (SGLT2-is), like Dapagliflozin, delaying the progression of DN. However, the underlying mechanisms of SGLT2 associated with podocyte injury are still not fully elucidated. Methods: Through mRNA sequencing, streptozotocin-induced and Dapagliflozin-intraperitoneal injection mice models were established to explore potential mechanism between Dapagliflozin and renal phenotype. And all changes referring this observed pathway were proven repeatedly in podocyte. Results: Here, we generated the streptozotocin-induced DN models and found the accumulation of nephrotoxin and pathological lesions of the kidney, including interstitial inflammatory infiltration, mesangial expansion and glomerular sclerosis, while low expression of SGLT2 mitigated these injuries in Dapagliflozin-treated mice. Moreover, mRNA expression profile in these treated models determined the significance of insulin-like growth factor-1 receptor (IGF1R)/PI3K regulatory axis in glomerular injury. Particularly, SGLT2-is inhibited the increase of mesenchymal marker, α-SMA and the decrease of podocyte marker, nephrin at the gene or protein level. KEGG analysis also showed the enrichment of phosphatidylinositol signaling system and TGF-β/smad pathway. In parallel, the protein level of IGF1R, phosphorylated PI3K, and α-SMA were increased in high-glucose stimulated human podocyte, and reduced in Dapagliflozin (50nM and 100nM) or OSI-906 (inhibitor of IGF1R, 60nM) used groups. Notably, combination of the two inhibitors produced an accumulative effect in the protection of podocyte integrity. Mechanistically, IGF1 or IGF2 could bind to IGF1 receptors to mediate the epithelial-mesenchymal transition (EMT) of diabetic podocyte in response to the upregulation of SGLT2. Indeed, we enrolled the urine and plasma samples from a cohort consisting of 13 healthy people, and a cohort of 19 patients with DN using SGLT2-inhibitors (n=9) or not (n=10). Compared with pure DN patients, Elisa results suggested an increased circulation and excretion level of IGF1/2 in SGLT2-is used DN cohort. Conclusions: Taken together, our study reported the key role of SGLT2/IGF1R/PI3K signaling in regulating podocyte EMT. Modulating the IGF1R expression may provide a novel idea for DN therapy.

Project description:BACKGROUND: Heart failure (HF) is one of the leading causes of mortality worldwide. Extracellular vesicles (EVs) including small EVs, or exosomes and their molecular cargo are known to modulate cell to cell communication during multiple cardiac diseases. However, the role of systemic EV biogenesis inhibition in the models of HF is not well documented and remains unclear. METHODS: We investigated the role of circulating exosomes during cardiac dysfunction and remodeling in a mouse transverse aortic constriction (TAC) model of HF. Importantly, we investigate the efficacy of Tipifarnib (Tip), a recently identified exosome biogenesis inhibitor that targets the critical proteins (Rab27a, nSmase2 and Alix) involved in exosome biogenesis for this mouse model of HF. In this study, 10-week-old male mice underwent TAC surgery, were randomly assigned to groups with and without Tip treatment (10 mg/kg three times/week) and monitored for 8 weeks and a comprehensive assessment was conducted through performed echocardiographic, histological, and biochemical studies. RESULTS: TAC significantly elevated circulating plasma exosomes and markedly increased cardiac left ventricular (LV) dysfunction, cardiac hypertrophy, and fibrosis. Furthermore, injection of plasma exosomes from TAC mice induced LV dysfunction and cardiomyocyte hypertrophy in uninjured mice without TAC. On the contrary, treatment of Tip in TAC mice reduced circulating exosomes to baseline and remarkably improved LV functions, hypertrophy, and fibrosis. Tip treatment also drastically altered the miRNA profile of circulating post-TAC exosomes, including miR331-5p which was highly downregulated both in TAC circulating exosomes and in TAC cardiac tissue. Mechanistically, miR331-5p is crucial for inhibiting fibroblast-to-myofibroblast transition by targeting HOXC8, a critical regulator of fibrosis. Tipifarnib treatment in TAC mice upregulated the expression of miR331-5p that acts as potent repressor for one of the fibrotic mechanisms mediated by HOXC8. CONCLUSIONS: Our study underscores the pathological role of exosomes in HF and fibrosis in response to pressure overload. Tipifarnib mediated inhibition of exosome biogenesis and cargo sorting may serve as a viable strategy to prevent progressive cardiac remodeling to HF.

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Dapagliflozin protects against chronic heart failure in mice via inhibiting macrophage-mediated inflammation, independent of SGLT2 [RNA-Seq]

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