The Protective Role Of MiR-30 In Podocyte Injuries

Part One: mi R-30 protects podocyte through inhibiting u PAR-integrin β3 signaling.Urokinase plasminogen activator receptor(u PAR)is upregulated in podocytes of glomerular diseases and crucially mediates podocyte injury through ITGB3.We have previously shown mi R-30 family functions to maintain podocyte structure and function by inhibiting injurious calcineurin-NFATC signaling,we wonder whether mi R-30-calcineurin-NFATC and u PAR-ITGB3,two of major pathways leading to podocyte injury,could interact.We found that podocyte-specific mi R-30 s knockdown induced u PAR upregulation and ITGB3 activation,accompanied by proteinuria and podocyte injury which were ameliorated by ITGB3 inhibitor,cyclo-RGDf K;in addition,mi R-30knockdown-induced u PAR upregulation and ITGB3 activation were abolished by calcineurin and NFATC inhibitors,respectively,indicating mi R-30 deficiency induces calcineurin-NFATC signaling,which in turn activates u PAR-ITGB3 pathway.In cultured podocytes,mi R-30 knockdown also caused u PAR-ITGB3 signaling activation,leading to Rho GTPase activation,synaptopodin downregulation and podocyte injuries.To explore the role of u PAR-ITGB3 signaling regulation by mi R-30 s in podocytopathy development,we treated mice with lipopolysaccharide(LPS)and found that mi R-30 s were downregulated in the podocytes,accompanied by u PAR upregulation and ITGB3activation;however,podocyte-specific transgenic mi R-30 acd abolished u PAR-ITGB3 signaling and ameliorated podocyte injury and proteinuria.In cultured podocytes,LPS also induced mi R-30 s downregulation,u PAR-ITGB3 activation and podocyte injury,which were all prevented by mi R-30 a overexpression.Taken together,u PAR-ITGB3 signaling is negatively regulated by mi R-30 s through calcineurin-NFATC pathway,a novel mechanism underlying podocyte injury in glomerular diseases.Our study has elucidated the relationship among the crucial players governing podocyte pathophysiology and the actions of drugs commonly used for podocytopathies.Part two: mi R-30 suppression of SOCS3 attenuates inflammatory podocyte injuryExcessive renal inflammation associated with various acute and chronic kidney diseases often results in podocyte damage and glomerular injuries,which are influenced by aberrant epigenetic alterations.However,podocyte itself possesses inflammation-regulatory capabilities that might in turn affect the renal inflammatory processes.Whether epigenetic alterations regulate podocytic inflammation and its functional relevance to inflammatory kidney diseases remain largely unknown.In this study we discovered that endotoxin lipopolysaccharide(LPS)-induced acute renal inflammation and glomerular injury are accompanied by a marked suppression of glomerular mi R-30 family(mi R-30a-e).Exogenous supplementation of mi R-30 a,the major family member,alleviated LPS-induced podocytic pro-inflammatory NF-κB signaling,cytokine induction,migration and phagocytosis,indicating that mi R-30 s are negative regulators of podocytic inflammation.Further,mi R-30 a targeted and suppressed SOCS3(suppressor of cytokine signaling 3),an inducible inhibitor of JAK/STAT signaling,and inhibited the podocytic inflammatory responses in a SOCS3inhibition-dependent manner.Moreover,transgenic mice over-expressing mi R-30 a in podocytes inhibited the induction of renal SOCS3 and inflammatory cytokines,alleviated podocyte phagocytic activities,and reduced the glomerular structural and functional losses incurred by LPS.Thus,our results demonstrate that mi R-30 s inhibition of SOCS3 forms a critical regulatory loop that controls podocytic inflammation and that maintaining mi R-30 s protects kidney from acute renal inflammation and the associated glomerular injuries.