Faculty Opinions recommendation of Fluorofenidone attenuates tubulointerstitial fibrosis by inhibiting TGF-β(1)-induced fibroblast activation.

It is well recognized that murine double minute gene 2 (MDM2) plays a critical role in cell proliferation and inflammatory processes during tumorigenesis. It is also reported that MDM2 is expressed in glomeruli and involved in podocyte injury. However, whether MDM2 is implicated in renal fibrosis remains unclear. Here we investigated the role of MDM2 in tubulointerstitial fibrosis (TIF). By immunohistochemical staining and Western blotting we confirmed that MDM2 is upregulated in the tubulointerstitial compartment in patients with TIF and unilateral urethral obstruction (UUO) mice, which mainly originates from myofibroblasts. Consistently, in vitro MDM2 is increased in TGF-β1-treated fibroblasts, one of the major sources of collagen-producing myofibroblasts during TIF, along with fibroblast activation. Importantly, genetic deletion of MDM2 significantly attenuates fibroblast activation. We then analyzed the possible downstream signaling of MDM2 during fibroblast activation. p53-dependent pathway is the classic downstream signaling of MDM2, and Nutlin-3 is a small molecular inhibitor of MDM2-p53 interaction. To our surprise, Nutlin-3 could not ameliorate fibroblast activation in vitro and TIF in UUO mice. However, we found that Notch1 signaling is attenuated during fibroblast activation, which could be markedly rescued by MDM2 knockdown. Overexpression of intracellular domain of Notch1 (NICD) by plasmid could obviously minimize fibroblast activation induced by TGF-β1. In addition, the degradation of NICD is strikingly suppressed by PYR-41, an inhibitor of ubiquitin-activating enzyme E1, and proteasome inhibitor MG132. Taken together, our findings provide the first evidence that MDM2 is involved in fibroblast activation and TIF, which associates with Notch1 ubiquitination and proteasome degradation.

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Inhibition of SIRT2 Alleviates Fibroblast Activation and Renal Tubulointerstitial Fibrosis via MDM2

Cellular Physiology and Biochemistry ◽

10.1159/000488613 ◽

2018 ◽

Vol 46 (2) ◽

pp. 451-460 ◽

Cited By ~ 4

Author(s):

Fang-Fang He ◽

Ren-Yu You ◽

Chen Ye ◽

Chun-Tao Lei ◽

Hui Tang ◽

...

Keyword(s):

Epithelial Cells ◽

Western Blot ◽

Tubulointerstitial Fibrosis ◽

Tubular Epithelial Cells ◽

Mesenchymal Transition ◽

Fibroblast Activation ◽

Renal Tubulointerstitial Fibrosis ◽

Collagen Iii ◽

Chemical Inhibition ◽

Tgf Β1

Background/Aims: Renal tubular epithelial cells and fibroblasts are the main sources of myofibroblasts, and these cells produce the extracellular matrix during tubulointerstitial fibrosis (TIF). Histone deacetylases (HDAC) inhibitors exert an antifibrogenic effect in the skin, liver and lung. Sirtuin 2 (SIRT2), which is a class III HDAC, is an important member of NAD+-dependent protein deacetylases. The current study evaluated the role of SIRT2 in renal TIF. Methods: Immunohistochemical staining and Western blot were performed to evaluate SIRT2 expression in TIF patients and unilateral urethral obstruction (UUO) mice. Western blot was used to assess the protein levels of SIRT2, α-SMA, collagen III, fibronectin, and MDM2 in tubular epithelial cells and fibroblasts. The specific inhibitor AGK2 was used to inhibit SIRT2 activity, and targeted siRNA was used to suppress SIRT2 expression. Results: SIRT2 expression increased in the tubulointerstitium of TIF patients and UUO mice. SIRT2 inhibition ameliorated TIF in UUO mice. SIRT2 expression in tubular cells was unchanged after exposure to TGF-β1. The SIRT2-specifc inhibitor AGK2 did not attenuate TGF-β1-induced tubular epithelial-mesenchymal transition. However, SIRT2 was upregulated in fibroblasts, and fibroblasts were activated after TGF-β1 treatment. Genetic knockdown and chemical inhibition of SIRT2 attenuated TGF-β1-induced fibroblast activation. We also explored the downstream signaling of SIRT2 during fibroblast activation. Genetic knockdown and chemical inhibition of SIRT2 suppressed TGF-β1-induced increase in MDM2 expression, and inhibition of the MDM2-p53 interaction using Nutlin-3 did not suppress SIRT2 upregulation. Conclusion: Our results suggest that SIRT2 participates in the activation of fibroblasts and TIF, which is mediated via regulation of the MDM2 pathway, and the downregulation of SIRT2 may be a therapeutic strategy for renal fibrosis.

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Fluorofenidone Attenuates Tubulointerstitial Fibrosis by Inhibiting TGF-β1-Induced Fibroblast Activation

American Journal of Nephrology ◽

10.1159/000329080 ◽

2011 ◽

Vol 34 (2) ◽

pp. 181-194 ◽

Cited By ~ 18

Author(s):

Qiongjing Yuan ◽

Rui Wang ◽

Yu Peng ◽

Xiao Fu ◽

Wei Wang ◽

...

Keyword(s):

Tubulointerstitial Fibrosis ◽

Fibroblast Activation ◽

Tgf Β1

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BMPER Ameliorates Renal Fibrosis by Inhibiting Tubular Dedifferentiation and Fibroblast Activation

Frontiers in Cell and Developmental Biology ◽

10.3389/fcell.2021.608396 ◽

2021 ◽

Vol 9 ◽

Author(s):

Ting Xie ◽

Zunen Xia ◽

Wei Wang ◽

Xiangjun Zhou ◽

Changgeng Xu

Keyword(s):

Kidney Disease ◽

Renal Fibrosis ◽

Therapeutic Potential ◽

Interstitial Fibrosis ◽

Tubulointerstitial Fibrosis ◽

Tubular Damage ◽

Mesenchymal Transition ◽

Fibroblast Activation ◽

Tgf Β1 ◽

E Cadherin

Tubulointerstitial fibrosis is both a pathological manifestation of chronic kidney disease and a driving force for the progression of kidney disease. A previous study has shown that bone morphogenetic protein-binding endothelial cell precursor-derived regulator (BMPER) is involved in lung fibrogenesis. However, the role of BMPER in renal fibrosis remains unknown. In the present study, the expression of BMPER was examined by real-time PCR, Western blot and immunohistochemical staining. The in vitro effects of BMPER on tubular dedifferentiation and fibroblast activation were analyzed in cultured HK-2 and NRK-49F cells. The in vivo effects of BMPER were dissected in unilateral ureteral obstruction (UUO) mice by delivery of BMPER gene via systemic administration of plasmid vector. We reported that the expression of BMPER decreased in the kidneys of UUO mice and HK-2 cells. TGF-β1 increased inhibitor of differentiation-1 (Id-1) and induced epithelial mesenchymal transition in HK-2 cells, and knockdown of BMPER aggravated Id-1 up-regulation, E-cadherin loss, and tubular dedifferentiation. On the contrary, exogenous BMPER inhibited Id-1 up-regulation, prevented E-cadherin loss and tubular dedifferentiation after TGF-β1 exposure. In addition, exogenous BMPER suppressed fibroblast activation by hindering Erk1/2 phosphorylation. Knockdown of low-density lipoprotein receptor-related protein 1 abolished the inhibitory effect of BMPER on Erk1/2 phosphorylation and fibroblast activation. Moreover, delivery of BMPER gene improved renal tubular damage and interstitial fibrosis in UUO mice. Therefore, BMPER inhibits TGF-β1-induced tubular dedifferentiation and fibroblast activation and may hold therapeutic potential for tubulointerstitial fibrosis.

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MAD2B-mediated SnoN downregulation is implicated in fibroblast activation and tubulointerstitial fibrosis

AJP Renal Physiology ◽

10.1152/ajprenal.00600.2015 ◽

2016 ◽

Vol 311 (1) ◽

pp. F207-F216 ◽

Cited By ~ 5

Author(s):

Hui Tang ◽

Hua Su ◽

Di Fan ◽

Chen Ye ◽

Chun-Tao Lei ◽

...

Keyword(s):

Transforming Growth Factor ◽

Mitotic Checkpoint ◽

Tubulointerstitial Fibrosis ◽

Renal Diseases ◽

Kidney Cortex ◽

Dependent Manner ◽

Checkpoint Control ◽

Fibroblast Activation ◽

Tgf Β1

MAD2B, an anaphase-promoting complex/cyclosome (APC/C) inhibitor and a small subunit of DNA polymerase ζ, is indispensible for mitotic checkpoint control and DNA repair. Previously, we established that MAD2B is expressed in glomerular and tubulointerstitial compartments and participates in high glucose-induced podocyte injury. However, its role in other renal diseases remains elusive. In the present study, we aim to illustrate the potential role of MAD2B in the pathogenesis of renal fibrosis. By immunofluorescence and Western blotting, we found MAD2B expression is obviously increased in tubulointerstitial fibrosis (TIF) patients and unilateral ureteral obstruction (UUO) mice. It is widely accepted that resident fibroblasts are the major source of collagen-producing myofibroblasts during TIF. Therefore, we evaluated the level of MAD2B in fibroblasts (NRK-49F) exposed to transforming growth factor (TGF)-β1 by immunoblotting and revealed that MAD2B is upregulated in a time-dependent manner. Intriguingly, SnoN, a transcriptional repressor of the TGF-β1/Smad signaling pathway, is decreased in TGF-β1-treated fibroblasts as well as the kidney cortex from TIF patients and UUO mice. Either in vitro or in vivo, local genetic depletion of MAD2B by lentiviral transfection could preserve SnoN abundance and suppress Smad3 phosphorylation, which finally dampens fibroblast activation, ECM accumulation, and alleviates the severity of TIF. However, the ubiquitin ligase APC/C is not involved in the MAD2B-mediated SnoN decline, although this process is ubiquitination dependent. In conclusion, our observation proposes that besides cell cycle management, MAD2B has a profibrotic role during fibroblast activation and TIF by suppressing SnoN expression. Targeting the MAD2B-SnoN pathway is a promising intervention for TIF.

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