Up-regulation of the human-specific CHRFAM7A gene protects against renal fibrosis in mice with obstructive nephropathy

Renal fibrosis is a major factor in the progression of chronic kidney diseases. Obstructive nephropathy is a common cause of renal fibrosis, which is also accompanied by inflammation. To explore the effect of human-specific CHRFAM7A expression, an inflammation-related gene, on renal fibrosis during obstructive nephropathy, we studied CHRFAM7A transgenic mice and wild type mice that underwent unilateral ureteral obstruction (UUO) injury. Transgenic overexpression of CHRFAM7A gene inhibited UUO-induced renal fibrosis, which was demonstrated by decreased fibrotic gene expression and collagen deposition. Furthermore, kidneys from transgenic mice had reduced TGF-β1 and Smad2/3 expression following UUO compared with those from wild type mice with UUO. In addition, the overexpression of CHRFAM7A decreased release of inflammatory cytokines in the kidneys of UUO-injured mice. In vitro, the overexpression of CHRFAM7A inhibited TGF-β1-induced increase in expression of fibrosis-related genes in human renal tubular epithelial cells (HK-2 cells). Additionally, up-regulated expression of CHRFAM7A in HK-2 cells decreased TGF-β1-induced epithelial-mesenchymal transition (EMT) and inhibited activation f TGF-β1/Smad2/3 signalling pathways. Collectively, our findings demonstrate that overexpression of the human-specific CHRFAM7A gene can reduce UUO-induced renal fibrosis by inhibiting TGF-β1/Smad2/3 signalling pathway to reduce inflammatory reactions and EMT of renal tubular epithelial cells.     

Suppression of LMCD1 ameliorates renal fibrosis by blocking the activation of ERK pathway

Tubulointerstitial fibrosis is a common pathway of chronic kidney disease (CKD) and is closely related to the progression of CKD. LMCD1, acting as an intermediary, has been reported to play a role in cardiac fibrosis. However, its role in renal fibrosis is yet to be deciphered. Based on the GEO database, we found the expression of LMCD1 is increased in kidney tissues of CKD patients and in human proximal tubular epithelial (HK-2) cells treated with transforming growth factor-β1 (TGF-β1), suggesting that LMCD1 may be involved in tubulointerstitial fibrosis. Herein, we investigated the role of LMCD1 in mice with unilateral ureteral obstruction (UUO) and in TGF-β1-stimulated HK-2 cells. In the UUO model, the expression of LMCD1 was upregulated. UUO-induced renal histopathological changes were mitigated by knockdown of LMCD1. LMCD1 silence alleviated renal interstitial fibrosis in UUO mice by decreasing the expression of TGF-β1, fibronectin, collagen I, and collagen III. LMCD1 deficiency suppressed cell apoptosis in kidney to prevent UUO-triggered renal injury. Furthermore, LMCD1 deficiency blocked the activation of ERK signaling in UUO mice. In vitro, LMCD1 was upregulated in HK-2 cells after TGF-β1 stimulation. LMCD1 silence abrogated TGF-β1-mediated upregulation of fibrotic genes. Treatment of HK-2 cells with ERK-specific inhibitor SCH772984 and agonist TPA validated LMCD1 exerted its function via activating ERK signaling. Together, our findings suggest that inhibition of LMCD1 protects against renal interstitial fibrosis by impeding ERK activation.     

HSP47 regulates ECM accumulation in renal proximal tubular cells induced by TGF-β1 through ERK1/2 and JNK MAPK pathways

Heat shock protein (HSP)47 is a collagen-specific molecular chaperone that is essential for the biosynthesis of collagen molecules. It is likely that increased levels of HSP47 contribute to the assembly of procollagen and thereby cause an excessive accumulation of collagens in disease processes associated with fibrosis. Although HSP47 promotes renal fibrosis, the underlying mechanism and associated signaling events have not been clearly delineated. We examined the role of HSP47 in renal fibrosis using a rat unilateral ureteral obstruction model and transforming growth factor (TGF)-β(1)-treated human proximal tubular epithelial (HK-2) cells. An upregulation of HSP47 in both in vivo and in vitro models was observed, which correlated with the increased synthesis of extracellular matrix (ECM) proteins and expression of tissue-type plasminogen activator inhibitor (PAI)-1. Blockade of HSP47 by short interfering RNA suppressed the expression of ECM proteins and PAI-1. In addition, TGF-β(1)-induced HSP47 expression in HK-2 cells was attenuated by ERK1/2 and JNK MAPK inhibitors. These data suggest that ERK1/2 and JNK signaling events are involved in modulating the expression of HSP47, the chaperoning effect of which on TGF-β(1) would ultimately contribute to renal fibrosis by enhancing the synthesis and deposition of ECM proteins.     

LncRNA ENST00000453774.1 contributes to oxidative stress defense dependent on autophagy mediation to reduce extracellular matrix and alleviate renal fibrosis

Although long noncoding RNA (LncRNA) are important players in the initiation and progression of many pathological processes, the role of LncRNAENST00000453774.1 (LncRNA 74.1) in renal fibrosis still remains unclear. Lentivirus mediated LncRNA 74.1 overexpressing HK2 cells and overexpression mice models were constructed. HK2 cells induced by transforming growth factor-β (TGF-β) in vitro, and the mice UUO model in vivo were used to simulate renal fibrosis. The expression of LncRNA 74.1 was significantly downregulated in the TGF-β-induced HK-2 cell fibrosis and clinical renal fibrosis specimens. LncRNA 74.1 overexpression obviously attenuated renal fibrosis in vitro and unilateral ureteral obstruction-induced renal fibrosis in vivo. LncRNA 74.1 promoted reactive oxygen species defense by activating prosurvival autophagy then decreased ECM-related proteins fibronectin and collagen I involved in renal fibrosis. We also found that Nrf2-keap1 signaling played important roles in the remission of ECM mediated by LncRNA 74.1. This study indicates that LncRNA 74.1 downregulation would contribute to renal fibrosis and its overexpression might represent a novel anti-fibrotic treatment in renal diseases.     

C1q/tumor necrosis factor-related protein-3 improves renal fibrosis via inhibiting notch signaling pathways

C1q/tumor necrosis factor-related protein-3 (CTRP3) has been extensively reported as an important role involved in antifibrosis, antiapoptosis, and anti-inflammation. However, the role of CTRP3 involved in renal fibrosis remains unclear. Our current study explored the role of CTRP3 in renal fibrosis and its underlying mechanisms by using serums and renal biopsy specimens from renal fibrosis patients and control subjects, rats models with the surgery of unilateral ureteral obstruction (UUO) and human renal proximal tubular epithelial cells (HRPTEpiCs). We found that circulating levels of CTRP3 had no significant difference between renal fibrosis patients and healthy subjects; however, renal CTRP3 expression was markedly downregulated in the fibrotic region with an abundant expression of collagen-I. In UUO rat models, circulating levels of CTRP3 have not changed with the prolonged obstruction of the kidney; renal CTRP3 expression was decreased with the severity of renal fibrosis; adenovirus-mediated CTRP3 treatment inhibited renal interstitial fibrosis. In vitro experiments revealed that CTRP3 attenuates TGF-β1 induced tubular epithelial cells fibrotic changes; CTRP3 knockdown facilitates the expression of fibrotic markers in TGF-β1-induced HRPTEpiCs; recombinant CTRP3 or adenovirus-mediated CTRP3 overexpression significantly inhibited the Notch signaling pathway-associated factors, and knockdown of CTRP3 increased TGF-β1-mediated activation of the Notch signaling pathways. Collectively, our current study found that CTRP3 could improve renal fibrosis, to some extent, through inhibiting the Notch pathway.     

The TGFβ-ERK pathway contributes to Notch3 upregulation in the renal tubular epithelial cells of patients with obstructive nephropathy

Renal interstitial fibrosis is a common renal injury resulted from a variety of chronic kidney conditions and an array of factors. We report here that Notch3 is a potential contributor. In comparison to 6 healthy individuals, a robust elevation of Notch3 expression was observed in the renal tubular epithelial cells of 18 patients with obstructive nephropathy. In a rat unilateral ureteral obstruction (UUO) model which mimics the human disease, Notch3 upregulation closely followed the course of renal injury, renal fibrosis, TGFβ expression, and alpha-smooth muscle actin (α-SMA) expression, suggesting a role of Notch3 in promoting tubulointerstitial fibrosis. This possibility was supported by the observation that TGFβ, the major renal fibrogenic cytokine, stimulated Notch3 expression in human proximal tubule epithelial HK-2 cells. TGFβ enhanced the activation of ERK, p38, but not JNK MAP kinases in HK-2 cells. While inhibition of p38 activation using SB203580 did not affect TGFβ-induced Notch3 expression, inhibition of ERK activation with a MEK1 inhibitor PD98059 dramatically reduced the event. Furthermore, enforced ERK activation through overexpression of the constitutively active MEK1 mutant MEK1Q56P upregulated Notch3 expression in HK-2 cells, and PD98059 reduced ERK activation and Notch3 expression in HK-2 cells expressing MEK1Q56P. Collectively, we provide the first clinical evidence for Notch3 upregulation in patients with obstructive nephropathy; the upregulation is likely mediated through the TGFβ-ERK pathway. This study suggests that Notch3 upregulation contributes to renal injury caused by obstructive nephropathy, which could be prevented or delayed through ERK inhibition.     

Melatonin ameliorates renal fibroblast-myofibroblast transdifferentiation and renal fibrosis through miR-21-5p regulation

Fibroblast-myofibroblast transdifferentiation (FMT) is widely recognized as the major pathological feature of renal fibrosis. Although melatonin has exerted antifibrogenic activity in many diseases, its role in renal FMT remains unclear. In the present study, the aim was to explore the effect of melatonin on renal FMT and the underlying mechanisms. We established the transforming growth factor (TGF)-β1 stimulated rat renal fibroblast cells (NRK-49F) model in vitro and unilateral ureteral obstruction (UUO) mice model in vivo. We assessed levels of α-smooth muscle actin (α-SMA), col1a1 and fibronectin, STAT3 and AP-1, as well as miR-21-5p and its target genes (Spry1, PTEN, Smurf2 and PDCD4). We found that melatonin reduced the expression of α-SMA, col1a1 and fibronectin, as well as the formation of α-SMA filament in TGF-β1-treated NRK-49F cells. Meanwhile, melatonin inhibited STAT3 phosphorylation, down-regulated miR-21-5p expression, and up-regulated Spry1 and PTEN expression. Moreover, miR-21-5p mimics partially antagonized the anti-fibrotic effect of melatonin. For animal experiments, the results revealed that melatonin remarkably ameliorated UUO-induced renal fibrosis, attenuated the expression of miR-21-5p and pro-fibrotic proteins and elevated Spry1 and PTEN expression. Nevertheless, agomir of miR-21-5p blocked the renoprotective effect of melatonin in UUO mice. These results indicated that melatonin could alleviate TGF-β1-induced renal FMT and UUO-induced renal fibrosis through down-regulation of miR-21-5p. Regulation of miR-21-5p/PTEN and/or miR-21-5p/Spry1 signal might be involved in the anti-fibrotic effect of melatonin in the kidneys of UUO mice.     

A bioinformatics and network pharmacology approach to the mechanisms of action of Shenxiao decoction for the treatment of diabetic nephropathy

BackgroundThe epithelial-to-mesenchymal transition (EMT) of renal tubular epithelial cells is the main pathological alteration in diabetic nephropathy (DN). Traditional Chinese medicine (TCM) has been used for the treatment of DN in clinical practice and has been proven to be effective.PurposeThis aim of this study was to shed light on the efficacy of Shenxiao decoction (SXD) on the EMT of renal tubular epithelial cells and the molecular mechanisms of SXD in mice with DN, as well as on the high glucose (HG)- and TGF-β1-induced EMT of NRK-52E and HK-2 cells.Study design and methodsA bioinformatics and network pharmacology method were utilized to construct the active ingredient-target networks of SXD that were responsible for the beneficial effects against DN. The effects of RUNX3 were validated in HG- and TGF-β1-induced EMT processes in NRK-52E and HK-2 cells.ResultsBioinformatics analysis revealed that 122 matching targets were closely associated with the regulation of cell migration and the AGE-RAGE signaling pathway in diabetic complications. The results also revealed that, relative to the mice with DN, the mice in the treatment group had an improved general state and reduced blood glucose levels. The degradation of renal function was ameliorated by SXD. Moreover, the protective effects of SXD were also observed on renal structural changes. Furthermore, SXD suppressed the activation of the transforming growth factor (TGF)-β1/Smad pathway and upregulated the RUNX3 and E-cadherin levels and downregulated the extracellular matrix (ECM) protein levels in mice with DN. SXD was further found to prevent the HG- and TGF-β1-induced EMT processes in NRK-52E and HK-2 cells. Additionally, the overexpression of RUNX3 markedly inhibited the EMT and TGF-β1/Smad pathway induced by HG and TGF-β1 in NRK-52E and HK-2 cells.ConclusionTaken together, these results suggest that SXD maybe alleviate EMT in DN via the inhibition of the TGF-β1/Smad/RUNX3 signaling pathway under hyperglycemic conditions.     

Mindin deficiency alleviates renal fibrosis through inhibiting NF-κB and TGF-β/Smad pathways

Renal fibrosis acts as a clinical predictor in patients with chronic kidney disease and is characterized by excessive extracellular matrix (ECM) accumulation. Our previous study suggested that mindin can function as a mediator for liver steatosis pathogenesis. However, the role of mindin in renal fibrosis remains obscure. Here, tumour necrosis factor (TGF)-β-treated HK-2 cells and global mindin knockout mouse were induced with renal ischaemia reperfusion injury (IRI) to test the relationship between mindin and renal fibrosis. In vitro, mindin overexpression promoted p65—the hub subunit of the NF-κB signalling pathway—translocation from the cytoplasm into the nucleus, resulting in NF-κB pathway activation in TGF-β-treated HK-2 cells. Meanwhile, mindin activated the TGF-β/Smad pathway, thereby causing fibrotic-related protein expression in vitro. Mindin^−/− mice exhibited less kidney lesions than controls, with small renal tubular expansion, inflammatory cell infiltration, as well as collagen accumulation, following renal IRI. Mechanistically, mindin^−/− mice suppressed p65 translocation and deactivated NF-κB pathway. Simultaneously, mindin disruption inhibited the TGF-β/Smad pathway, alleviating the expression of ECM-related proteins. Hence, mindin may be a novel target of renal IRI in the treatment of renal fibrogenesis.     

TGFβ-Stimulated MicroRNA-21 Utilizes PTEN to Orchestrate AKT/mTORC1 Signaling for Mesangial Cell Hypertrophy and Matrix Expansion

Transforming growth factor-β (TGFβ) promotes glomerular hypertrophy and matrix expansion, leading to glomerulosclerosis. MicroRNAs are well suited to promote fibrosis because they can repress gene expression, which negatively regulate the fibrotic process. Recent cellular and animal studies have revealed enhanced expression of microRNA, miR-21, in renal cells in response to TGFβ. Specific miR-21 targets downstream of TGFβ receptor activation that control cell hypertrophy and matrix protein expression have not been studied. Using 3'UTR-driven luciferase reporter, we identified the tumor suppressor protein PTEN as a target of TGFβ-stimulated miR-21 in glomerular mesangial cells. Expression of miR-21 Sponge, which quenches endogenous miR-21 levels, reversed TGFβ-induced suppression of PTEN. Additionally, miR-21 Sponge inhibited TGFβ-stimulated phosphorylation of Akt kinase, resulting in attenuation of phosphorylation of its substrate GSK3β. Tuberin and PRAS40, two other Akt substrates, and endogenous inhibitors of mTORC1, regulate mesangial cell hypertrophy. Neutralization of endogenous miR-21 abrogated TGFβ-stimulated phosphorylation of tuberin and PRAS40, leading to inhibition of phosphorylation of S6 kinase, mTOR and 4EBP-1. Moreover, downregulation of miR-21 significantly suppressed TGFβ-induced protein synthesis and hypertrophy, which were reversed by siRNA-targeted inhibition of PTEN expression. Similarly, expression of constitutively active Akt kinase reversed the miR-21 Sponge-mediated inhibition of TGFβ-induced protein synthesis and hypertrophy. Furthermore, expression of constitutively active mTORC1 prevented the miR-21 Sponge-induced suppression of mesangial cell protein synthesis and hypertrophy by TGFβ. Finally, we show that miR-21 Sponge inhibited TGFβ-stimulated fibronectin and collagen expression. Suppression of PTEN expression and expression of both constitutively active Akt kinase and mTORC1 independently reversed this miR-21-mediated inhibition of TGFβ-induced fibronectin and collagen expression. Our results uncover an essential role of TGFβ-induced expression of miR-21, which targets PTEN to initiate a non-canonical signaling circuit involving Akt/mTORC1 axis for mesangial cell hypertrophy and matrix protein synthesis.     

Focal adhesion kinase (FAK)-related non-kinase inhibits myofibroblast differentiation through differential MAPK activation in a FAK-dependent manner

Transforming growth factor (TGF)-beta1 induces fibroblast transdifferentiation to myofibroblasts, a process that requires the involvement of integrin-mediated signaling and focal adhesion kinase (FAK). FAK-related non-kinase (FRNK) is known for its role in inhibiting integrin-mediated cell migration; however, its role in myofibroblast differentiation has not been defined. Here, we report that FRNK abrogates TGF-beta1-induced myofibroblast differentiation in vitro and in vivo. TGF-beta1 can induce alpha-smooth muscle actin (alpha-SMA) expression in the presence or absence of FAK; however, TGF-beta1-induced alpha-SMA expression is reduced (approximately 73%) in FAK-deficient fibroblasts. Although both ERK and p38 MAPK activation is required for maximal TGF-beta1-induced alpha-SMA expression, ERK is the major signaling intermediate in cells that express FAK. In contrast, p38 MAPK is the dominant mediator of TGF-beta1-induced alpha-SMA expression in FAK-deficient cells. FRNK overexpression blocks TGF-beta1-induced ERK or p38 MAPK activation in the presence, and surprisingly, in the absence of FAK. The loss of FRNK was tested in vivo during experimentally induced pulmonary fibrosis in mice. FRNK knock-out mice have a greater increase in alpha-SMA-expressing cells in response to a pulmonary fibrotic stimulus in vivo, as compared with congenic wild type mice. This is the first time that FRNK loss has been shown to modify the pathobiology in any animal disease model. Together, the data demonstrate that FRNK negatively regulates myofibroblast differentiation in vitro and in vivo. These data further suggest that modulation FRNK expression may be a novel avenue for therapeutic intervention in tissue fibrosis.     

Therapeutic DNA vaccine encoding CEMIP (KIAA1199) ameliorates kidney fibrosis in obesity through inhibiting the Wnt/β-catenin pathway

BackgroundCEMIP is a novel risk factor of various cancers through activating Wnt/β-catenin /epithelial-mesenchymal transition between epithelial cells and stroma. The chronic fibrosis commonly contributes renal carcinogenesis in patients with obesity. As there have very few choices of medicines targeting CEMIP. This study intended to design therapeutic DNA vaccines for nephropathy in obesity, through diminishing the CEMIP/Wnt1/β-catenin pathway.MethodIn an 8-week experiment, plasmid-encoding CEMIP was vaccinated into high-fat diet (HFD) or obesity mice in the first 4 weeks, and then vaccination was stopped for at least 4 weeks. Then, plasma and spleens were harvested to evaluate anti-CEMIP antibody synthesis and T-helper type 1 and 2 activation after vaccination. Kidneys were collected to investigate efficacy of CEMIP DNA vaccine on inhibiting HFD and obesity-induced fibrosis and Wnt1/β-catenin pathway. To confirm that CEMIP crucially contributed towards fibrotic formation, CEMIP gene or siRNA transfection was performed in HK-2 cells under VLDL stimulation, or not.ResultsAt the end point, anti-CEMIP antibody was successfully produced in the pcDNA 3.1-CEMIP vaccinated group, while Wnt1/β-catenin signaling and fibrosis was inactive. Through VLDL stimulation and CEMIP overexpression, Wnt1/β-catenin signaling and fibrosis significantly presented in vitro. Otherwise, anti-sera of CEMIP-vaccinated mice could inhibit the VLDL-induced Wnt1/β-catenin/fibrosis pathway in HK-2 cells. Similarly, the silencing of CEMIP by siRNA ameliorated the Wnt1/β-catenin pathway and fibrogenesis under VLDL stimulation.ConclusionDNA vaccine targeting CEMIP/Wnt1/β-catenin pathway plays a novel strategy in nephropathy.General significanceImmune therapy might provide a new therapeutic option on nephropathy of obesity.     

Lin28a attenuates TGF-β-induced renal fibrosis

Lin28a has diverse functions including regulation of cancer, reprogramming and regeneration, but whether it promotes injury or is a protective reaction to renal injury is unknown. We studied how Lin28a acts in unilateral ureteral obstruction (UUO)-induced renal fibrosis following unilateral ureteral obstruction, in a mouse model. We further defined the role of Lin28a in transforming growth factor (TGF)-signaling pathways in renal fibrosis through in vitro study using human tubular epithelium-like HK-2 cells. In the mouse unilateral ureteral obstruction model, obstruction markedly decreased the expression of Lin28a, increased the expression of renal fibrotic markers such as type I collagen, α-SMA, vimentin and fibronectin. In TGF-β-stimulated HK-2 cells, the expression of Lin28a was reduced and the expression of renal fibrotic markers such as type I collagen, α-SMA, vimentin and fibronectin was increased. Adenovirus-mediated overexpression of Lin28a inhibited the expression of TGF-β-stimulated type I collagen, α-SMA, vimentin and fibronectin. Lin28a inhibited TGF-β-stimulated SMAD3 activity, via inhibition of SMAD3 phos-phorylation, but not the MAPK pathway ERK, JNK or p38. Lin28a attenuates renal fibrosis in obstructive nephropathy, making its mechanism a possible therapeutic target for chronic kidney disease.     

Sphingosine kinase 1 protects renal tubular epithelial cells from renal fibrosis via induction of autophagy

Autophagy is an important homoeostatic mechanism for the lysosomal degradation of protein aggregates and damaged cytoplasmic components. Recent studies suggest that autophagy which is induced by TGF-β1 suppresses kidney fibrosis in renal tubular epithelial cells (RTECs) of obstructed kidneys. Sphingosine kinase 1(SK1), converting sphingosine into endogenous sphingosine-1-phosphate (S1P), was shown to modulate autophagy and involved in the processes of fibrotic diseases. Since SK1 activity is also up-regulated by TGF-β1, we explored its effect on the induction of autophagy and development of renal fibrosis in this study. In vitro, SK1 expression and activity were markedly increased by TGF-β1 stimulation in a time and concentration dependent manner, and concomitant changes in autophagic response were observed in HK-2 cells. Further, knockdown of SK-1 led to a decrease of autophagy whereas overexpression of SK1 caused a greater induction of autophagy. In addition, overexpression of SK1 resulted in decreased of mature TGF-β levels through autophagic degradation. In vivo, SK1 enzymatic activity and autophagic response were both up-regulated in a mouse model of kidney fibrosis induced by unilateral ureteral obstruction (UUO); meanwhile, increased of mature TGF-β1 and deposition of extracellular matrix (ECM) were observed in tubulointerstitial areas compared with sham-operated mice. However, aggravation of renal fibrosis was detected when SK1 inhibitor PF-543 was applied to suppress SK1 enzymatic activity in UUO mice. At the same time, autophagy was also inhibited by PF-543. Thus, our findings suggest that SK1 activation is renoprotective via induction of autophagy in the fibrotic process.     

PTEN alleviates maladaptive repair of renal tubular epithelial cells by restoring CHMP2A-mediated phagosome closure

Phosphatase and Tensin Homolog on chromosome Ten (PTEN) has emerged as a key protein that governs the response to kidney injury. Notably, renal adaptive repair is important for preventing acute kidney injury (AKI) to chronic kidney disease (CKD) transition. To test the role of PTEN in renal repair after acute injury, we constructed a mouse model that overexpresses PTEN in renal proximal tubular cells (RPTC) by crossing PTEN^fl-stop-fl mice with Ggt1-Cre mice. Mass spectrometry-based proteomics was performed after subjecting these mice to ischemia/reperfusion (I/R). We found that PTEN was downregulated in renal tubular cells in mice and cultured HK-2 cells subjected to renal maladaptive repair induced by I/R. Renal expression of PTEN negatively correlated with NGAL and fibrotic markers. RPTC-specific PTEN overexpression relieved I/R-induced maladaptive repair, as indicated by alleviative tubular cell damage, apoptosis, and subsequent renal fibrosis. Mass spectrometry analysis revealed that differentially expressed proteins in RPTC-specific PTEN overexpression mice subjected to I/R were significantly enriched in phagosome, PI3K/Akt, and HIF-1 signaling pathway and found significant upregulation of CHMP2A, an autophagy-related protein. PTEN deficiency downregulated CHMP2A and inhibited phagosome closure and autolysosome formation, which aggravated cell injury and apoptosis after I/R. PTEN overexpression had the opposite effect. Notably, the beneficial effect of PTEN overexpression on autophagy flux and cell damage was abolished when CHMP2A was silenced. Collectively, our study suggests that PTEN relieved renal maladaptive repair in terms of cell damage, apoptosis, and renal fibrosis by upregulating CHMP2A-mediated phagosome closure, suggesting that PTEN/CHMP2A may serve as a novel therapeutic target for the AKI to CKD transition.Subject terms: Macroautophagy, Kidney     

A novel reciprocal loop between microRNA-21 and TGFβRIII is involved in cardiac fibrosis

Cardiac fibrosis is characterized by aberrant proliferation of cardiac fibroblasts and exaggerated deposition of extracellular matrix (ECM) in the myocardial interstitial, and ultimately impairs cardiac function. It is still controversial whether microRNA-21 (miR-21) participates in the process of cardiac fibrosis. Our previous study confirmed that transforming growth factor beta receptor III (TGFβRIII) is a negative regulator of TGF-β pathway. Here, we aimed to decipher the relationship between miR-21 and TGFβRIII in the pathogenic process of myocardial fibrosis. We found that TGF-β1 and miR-21 were up-regulated, whereas TGFβRIII was down-regulated in the border zone of mouse hearts in response to myocardial infarction. After transfection of miR-21 into cardiac fibroblasts, TGFβRIII expression was markedly reduced and collagen content was increased. And, luciferase results confirmed that TGFβRIII was a target of miR-21. It suggests that up-regulation of miR-21 could increase the collagen content and at least in part through inhibiting TGFβRIII. Conversely, we also confirmed that overexpression of TGFβRIII could inhibit the expression of miR-21 and reduce collagen production in fibroblasts. Further studies showed that overexpression of TGFβRIII could also deactivate TGF-β1 pathway by decreasing the expression of TGF-β1 and phosphorylated-Smad3 (p-Smad3). TGF-β1 has been proven as a positive regulator of miR-21. Taken together, we found a novel reciprocal loop between miR-21 and TGFβRIII in cardiac fibrosis caused by myocardial infarction in mice, and targeting this pathway could be a new strategy for the prevention and treatment of myocardial remodeling.