Transforming Growth Factor β Integrates Smad 3 to Mechanistic Target of Rapamycin Complexes to Arrest Deptor Abundance for Glomerular Mesangial Cell Hypertrophy

Das, Falguni; Ghosh‐Choudhury, Nandini; Bera, Amit; Dey, Nirmalya; Abboud, Hanna E.; Kasinath, Balakuntalam S.; Choudhury, Goutam Ghosh

doi:10.1074/jbc.m113.455782

Cited by 31 publications

(50 citation statements)

References 64 publications

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“…Phosphorylation of Smad3 stimulates mTOR activation to increase the synthesis of collagen in mesangial cells (42). In another study, sustained activation of Smad3 by TGF-␤1 suppresses deptor expression to activate mTORC1 and mTORC2 in a similar cell type (39). In renal fibroblasts, Smad3-Nox4-induced ROS generation phosphorylates ERK1/2, leading to myofibroblastic transformation (56).…”

Section: Volume 290 • Number 52 • December 25 2015mentioning

confidence: 99%

Transforming Growth Factor β1-induced Apoptosis in Podocytes via the Extracellular Signal-regulated Kinase-Mammalian Target of Rapamycin Complex 1-NADPH Oxidase 4 Axis

Das

Nguyen

et al. 2015

Journal of Biological Chemistry

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TGF-␤ is a pleiotropic cytokine that accumulates during kidney injuries, resulting in various renal diseases. We have reported previously that TGF-␤1 induces the selective up-regulation of mitochondrial Nox4, playing critical roles in podocyte apoptosis. Here we investigated the regulatory mechanism of Nox4 up-regulation by mTORC1 activation on TGF-␤1-induced apoptosis in immortalized podocytes. TGF-␤1 treatment markedly increased the phosphorylation of mammalian target of rapamycin (mTOR) and its downstream targets p70S6K and 4EBP1. Blocking TGF-␤ receptor I with SB431542 completely blunted the phosphorylation of mTOR, p70S6K, and 4EBP1. Transient adenoviral overexpression of mTOR-WT and constitutively active mTOR⌬ augmented TGF-␤1-treated Nox4 expression, reactive oxygen species (ROS) generation, and apoptosis, whereas mTOR kinase-dead suppressed the above changes. In addition, knockdown of mTOR mimicked the effect of mTOR-KD. Inhibition of mTORC1 by low-dose rapamycin or knockdown of p70S6K protected podocytes through attenuation of Nox4 expression and subsequent oxidative stress-induced apoptosis by TGF-␤1. Pharmacological inhibition of the MEK-ERK cascade, but not the PI3K-Akt-TSC2 pathway, abolished TGF-␤1-induced mTOR activation. Inhibition of either ERK1/2 or mTORC1 did not reduce the TGF-␤1-stimulated increase in Nox4 mRNA level but significantly inhibited total Nox4 expression, ROS generation, and apoptosis induced by TGF-␤1. Moreover, double knockdown of Smad2 and 3 or only Smad4 completely suppressed TGF-␤1-induced ERK1/2-mTOR activation. Our data suggest that TGF-␤1 increases translation ofNox4throughtheSmad-ERK1/2-mTORC1axis,whichisindependent of transcriptional regulation. Activation of this pathway plays a crucial role in ROS generation and mitochondrial dysfunction, leading to podocyte apoptosis. Therefore, inhibition of the ERK1/2-mTORC1 pathway could be a potential therapeutic and preventive target in proteinuric and chronic kidney diseases.Podocyte damage is one of the key determinants of the majority of diabetic and non-diabetic glomerular diseases, leading to chronic kidney diseases and end-stage renal disease (1). Leakage of plasma proteins in the urine indicates the onset of renal diseases that are associated with podocyte injury (2-4). Recent evidence has shown that mammalian target of rapamycin (mTOR) 3 signaling activation is an important mediator of diabetic nephropathy in mice and humans (5, 6). Increased mTOR activity has been reported in different glomerular diseases, and mTORC1 inhibition by rapamycin and everolimus shows beneficial effects against diabetic nephropathy, focal segmental glomerulosclerosis, minimal change disease, membranous nephropathy, etc. (7-10). But contrasting evidence also indicates that mTORC1 inhibition by the immunosuppressive drug rapamycin leads proteinuria and podocyte apoptosis and develops primary focal segmental glomerulosclerosis in renal transplant recipients (11). Therefore, it might be important to investigate the detailed molecular mechanisms to...

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Section: Volume 290 • Number 52 • December 25 2015mentioning

confidence: 99%

Transforming Growth Factor β1-induced Apoptosis in Podocytes via the Extracellular Signal-regulated Kinase-Mammalian Target of Rapamycin Complex 1-NADPH Oxidase 4 Axis

Das

Nguyen

et al. 2015

Journal of Biological Chemistry

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“…Similarly, renal cortices from control and diabetic mice were harvested in the same radioimmune precipitation assay buffer. These cells and the renal cortices were lysed at 4°C for 30 min as described previously (11,17,22). The crude cell extracts were centrifuged at 12,000 ϫ g for 30 min at 4°C.…”

Section: Methodsmentioning

confidence: 99%

“…Immunoblotting was performed using the indicated antibodies, and the protein bands were developed with HRP-conjugated secondary antibody using ECL reagent as described previously (5,11,17). For immunoprecipitation, equal amounts of proteins were immunoprecipitated with FoxO1 antibody as described (17,22). The immunobeads were suspended in sample buffer followed by electrophoresis in SDS-polyacrylamide gel.…”

Section: Methodsmentioning

confidence: 99%

“…The luciferase activity in the cell lysates was determined using an assay kit according to the instructions of the vendor (22,23).…”

Section: Methodsmentioning

confidence: 99%

“…The PCR condition was 95°C for 10 min, followed by 40 cycles at 95°C for 30 s, 56°C for 30 s, and 72°C for 45 s. The data were normalized to GAPDH levels in the same sample (forward primer, 5Ј-GCTAA-CATCAAATGGGGTGATGCTG-3Ј; reverse primer, 5Ј-GAG-ATGATGACCCTTTTGGCCCCAC-3Ј). Data analyses were done by comparative C t method as described previously (22).…”

Section: Methodsmentioning

confidence: 99%

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High Glucose Forces a Positive Feedback Loop Connecting Akt Kinase and FoxO1 Transcription Factor to Activate mTORC1 Kinase for Mesangial Cell Hypertrophy and Matrix Protein Expression

Das

Ghosh‐Choudhury

Dey

et al. 2014

Journal of Biological Chemistry

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High glucose increases miR‐214 to power a feedback loop involving PTEN and the Akt/mTORC1 signaling axis

et al. 2019

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The mechanism of PTEN repression by high glucose in diabetic nephropathy is not known. Using proximal tubular cells, we show that inhibition of PI3 kinase/Akt and their inactive enzymes prevents high glucose‐induced PTEN downregulation. Similarly, rapamycin (Rapa) and shRaptor block suppression of PTEN by high glucose. In contrast, the constitutive activation of Akt and mechanistic target of rapamycin (mTOR)C1 decrease the expression of PTEN, similarly to high glucose. Remarkably, PI3 kinase/Akt/mTORC1 inhibition significantly attenuates high glucose‐stimulated increase in miR‐214, which targets PTEN, while constitutively active Akt/mTORC1 increases miR‐214. Furthermore, anti‐miR‐214 and mTORC1 inhibition block high glucose‐induced hypertrophy and fibronectin expression. These results reveal the first evidence for the presence of a high glucose‐forced positive feedback conduit between the three‐layered kinase cascade and miR‐214/ PTEN in tubular cell injury.

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Transforming Growth Factor β Integrates Smad 3 to Mechanistic Target of Rapamycin Complexes to Arrest Deptor Abundance for Glomerular Mesangial Cell Hypertrophy

Cited by 31 publications

References 64 publications

Transforming Growth Factor β1-induced Apoptosis in Podocytes via the Extracellular Signal-regulated Kinase-Mammalian Target of Rapamycin Complex 1-NADPH Oxidase 4 Axis

Transforming Growth Factor β1-induced Apoptosis in Podocytes via the Extracellular Signal-regulated Kinase-Mammalian Target of Rapamycin Complex 1-NADPH Oxidase 4 Axis

High Glucose Forces a Positive Feedback Loop Connecting Akt Kinase and FoxO1 Transcription Factor to Activate mTORC1 Kinase for Mesangial Cell Hypertrophy and Matrix Protein Expression

High glucose increases miR‐214 to power a feedback loop involving PTEN and the Akt/mTORC1 signaling axis

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