AIM:To investigate the role and underlying mechanisms of NADPH oxidase 4(NOX4)/transient receptor potential channel subfamily C member 6(TRPC6)in the context of podocyte damage in diabetic nephropathya comprehensive investigative study was warranted.METHODS:(1)Male Sprague-Dawley rats were randomly divided in-to four distinct groups:a control group,a diabetic nephropathy group,a NOX4 inhibitor GKT137831-treated group,and a combined diabetic nephropathy with NOX4 inhibitor GKT137831-treated group,each consisting of 8～10 rats.The type 1 diabetes mellitus model was constructed via a single intraperitoneal injection of streptozotocin(STZ)(70 mg/kg),subse-quent to the successful induction of the model,GKT137831(at the dose of 5 mg/kg)was administered intraperitoneally.Regular monitoring of blood glucose levels was conducted,and urinary albumin excretion was quantified after 24 hours.Moreover,blood and kidney tissues were harvested for further analysis.(2)Mouse glomerular podocytes were divided into four distinct groups:a normal control group,a high glucose group,a GKT137831-treated group and a high glucose GKT137831-treated group.These podocytes were subsequently cultivated in vitro under high glucose conditions for 2 weeks.Thereafter,transfection of podocytes was carried out using NOX4 inhibitors and short interfering RNA targeting(siRNA)TRPC6.To detect the expression levels of NOX4 and TRPC6,a battery of techniques including Western blot,Immunohistochemistry,and reverse transcription polymerase chain reaction(RT-qPCR)were employed.(3)The morpho-logical changes of podocyte mitochondria under the condition of high glucose were observed by fluorescence confocal mi-croscopy,and the expression levels of peroxisome proliferator-activated receptor gamma coactivator 1α(PGC1α),mito-chondrial transcription factor A(TFAM),cytochromec oxidase subunit Ⅰ(COX Ⅰ)and cytochromec oxidase subunit Ⅳ(COX Ⅳ)in podocytes were assessed utilizing the Western blot technique.RESULTS:(1)Compared with normal con-trol group,mice with diabetic nephropathy manifested pronounced glomerular hypertrophy,thickening of basement mem-brane,expansion of the mesangial region,and an increased rate of urinary albumin excretion was observed.Analytical techniques such as Western blot and Immunohistochemistry showed a significant upsurge in the expression level of the NOX4 protein in kidney tissue,a diminished expression of glomerular podocyte protein(nephrin),an increased expression of interstitial cell markers(desmin),and an enhanced level of TRPC6 expression(P＜0.05).GKT137831 was assoiated with a reduction in desmin expression in renal tissue,preservation of glomerular nephrin expression,and a decrease in uri-nary albumin excretion(P＜0.05).(2)In vitro podocyte experiment,the expression of NOX4 and TRPC6 in podocyte was significantly increased in the context of high glucose(P＜0.05).Findings from Immunofluorescence and Western blot showed that GKT137831 effectively diminished the expression levels of TRPC6 and desmin while partially rescuing neph-rin expression in podocellular cells(P＜0.05).Western blot results showed that transfection of TRPC6 small interfering RNA could further promote the protective effect of GKT137831 on podiocytes.(3)Under high-glucose conditions,fluores-cence confocal microscopy revealed mitochondrial morphological damage in podocytes.However,therapeutic intervention with GKT137831 and transfection of TRPC6 siRNA partially rescued the mitochondrial structural integrity.Under high glucose conditions,immunoblot analysis demonstrated a marked decrement in the protein expression levels of PGC1α,TFAM,COX Ⅰ,and COX Ⅳ in podocytes.Importantly,GKT137831 and the transfection of TRPC6 siRNA significantly upregulated the levels of PGC1α,TFAM,COX Ⅰ,and COX Ⅳ(P＜0.05).CONCLUSION:In the context of the patho-genesis of diabetic nephropathy,the increased expression of NOX4 in the kidneys contributes to podocyte damage,with the effect being partially mediated via the TRPC6 channel.Inhibiting the NOX4-TRPC6 signaling pathway has the potential to ameliorate mitochondrial dysfunction in podocytes.This finding offers novel perspectives and strategies for the clinical di-agnosis and treatment of diabetic nephropathy.

AIM:To investigate the role and underlying mechanisms of NADPH oxidase 4(NOX4)/transient receptor potential channel subfamily C member 6(TRPC6)in the context of podocyte damage in diabetic nephropathya comprehensive investigative study was warranted.METHODS:(1)Male Sprague-Dawley rats were randomly divided in-to four distinct groups:a control group,a diabetic nephropathy group,a NOX4 inhibitor GKT137831-treated group,and a combined diabetic nephropathy with NOX4 inhibitor GKT137831-treated group,each consisting of 8～10 rats.The type 1 diabetes mellitus model was constructed via a single intraperitoneal injection of streptozotocin(STZ)(70 mg/kg),subse-quent to the successful induction of the model,GKT137831(at the dose of 5 mg/kg)was administered intraperitoneally.Regular monitoring of blood glucose levels was conducted,and urinary albumin excretion was quantified after 24 hours.Moreover,blood and kidney tissues were harvested for further analysis.(2)Mouse glomerular podocytes were divided into four distinct groups:a normal control group,a high glucose group,a GKT137831-treated group and a high glucose GKT137831-treated group.These podocytes were subsequently cultivated in vitro under high glucose conditions for 2 weeks.Thereafter,transfection of podocytes was carried out using NOX4 inhibitors and short interfering RNA targeting(siRNA)TRPC6.To detect the expression levels of NOX4 and TRPC6,a battery of techniques including Western blot,Immunohistochemistry,and reverse transcription polymerase chain reaction(RT-qPCR)were employed.(3)The morpho-logical changes of podocyte mitochondria under the condition of high glucose were observed by fluorescence confocal mi-croscopy,and the expression levels of peroxisome proliferator-activated receptor gamma coactivator 1α(PGC1α),mito-chondrial transcription factor A(TFAM),cytochromec oxidase subunit Ⅰ(COX Ⅰ)and cytochromec oxidase subunit Ⅳ(COX Ⅳ)in podocytes were assessed utilizing the Western blot technique.RESULTS:(1)Compared with normal con-trol group,mice with diabetic nephropathy manifested pronounced glomerular hypertrophy,thickening of basement mem-brane,expansion of the mesangial region,and an increased rate of urinary albumin excretion was observed.Analytical techniques such as Western blot and Immunohistochemistry showed a significant upsurge in the expression level of the NOX4 protein in kidney tissue,a diminished expression of glomerular podocyte protein(nephrin),an increased expression of interstitial cell markers(desmin),and an enhanced level of TRPC6 expression(P＜0.05).GKT137831 was assoiated with a reduction in desmin expression in renal tissue,preservation of glomerular nephrin expression,and a decrease in uri-nary albumin excretion(P＜0.05).(2)In vitro podocyte experiment,the expression of NOX4 and TRPC6 in podocyte was significantly increased in the context of high glucose(P＜0.05).Findings from Immunofluorescence and Western blot showed that GKT137831 effectively diminished the expression levels of TRPC6 and desmin while partially rescuing neph-rin expression in podocellular cells(P＜0.05).Western blot results showed that transfection of TRPC6 small interfering RNA could further promote the protective effect of GKT137831 on podiocytes.(3)Under high-glucose conditions,fluores-cence confocal microscopy revealed mitochondrial morphological damage in podocytes.However,therapeutic intervention with GKT137831 and transfection of TRPC6 siRNA partially rescued the mitochondrial structural integrity.Under high glucose conditions,immunoblot analysis demonstrated a marked decrement in the protein expression levels of PGC1α,TFAM,COX Ⅰ,and COX Ⅳ in podocytes.Importantly,GKT137831 and the transfection of TRPC6 siRNA significantly upregulated the levels of PGC1α,TFAM,COX Ⅰ,and COX Ⅳ(P＜0.05).CONCLUSION:In the context of the patho-genesis of diabetic nephropathy,the increased expression of NOX4 in the kidneys contributes to podocyte damage,with the effect being partially mediated via the TRPC6 channel.Inhibiting the NOX4-TRPC6 signaling pathway has the potential to ameliorate mitochondrial dysfunction in podocytes.This finding offers novel perspectives and strategies for the clinical di-agnosis and treatment of diabetic nephropathy.