Mesangial Cell Hypertrophy by High Glucose Is Mediated by Downregulation of the Tumor Suppressor PTEN

Glomerular hypertrophy is an early morphological alteration in diabetic nephropathy. Cyclin-Dependent Kinases have been shown to be required for high glucose (HG)-induced hypertrophy; however, the upstream regulators of CDKN1B in glomerular hypertrophy remain unclear. Herein we describe a novel pathway in which Long noncoding RNA (lncRNA) NEAT1 regulates the progression of mesangial cell hypertrophy via a competing endogenous RNA (ceRNA) mechanism. Real-time PCR was performed to detect the relative NEAT1 and miR-222-3p expressions and further confirmed the relationship between NEAT1 and miR-222-3p. Cell cycle was evaluated by flow cytometry. The related mechanisms were explored by Western blot, RNA immunoprecipitation and chromatin immunoprecipitation assay. We show that NEAT1 forms double stranded RNA (dsRNA) with miR-222-3p, thus limiting miR-222-3p’s binding with CDKN1B. This release of CDKN1B mRNA leads to elevated CDKN1B protein expression, resulting in hypertrophy. In addition, we demonstrated that STAT3 which is activated by HG induces the transcription of NEAT1 by binding to its promoter. Our findings underscore an unexpected role of lncRNAs on gene regulation and introduce a new mode of proliferation regulation in mesangial cells.

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High glucose upregulation of early-onset Parkinson's disease protein DJ-1 integrates the PRAS40/TORC1 axis to mesangial cell hypertrophy

Cellular Signalling ◽

10.1016/j.cellsig.2011.03.012 ◽

2011 ◽

Vol 23 (8) ◽

pp. 1311-1319 ◽

Cited By ~ 25

Author(s):

Falguni Das ◽

Nirmalya Dey ◽

Balachandar Venkatesan ◽

Balakuntalam S. Kasinath ◽

Nandini Ghosh-Choudhury ◽

...

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

High Glucose ◽

Early Onset ◽

Mesangial Cell ◽

Cell Hypertrophy ◽

Disease Protein ◽

Early Onset Parkinson’S Disease

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The cyclin kinase inhibitor p21WAF1, CIP1 is increased in experimental diabetic nephropathy: potential role in glomerular hypertrophy.

Journal of the American Society of Nephrology ◽

10.1681/asn.v96986 ◽

1998 ◽

Vol 9 (6) ◽

pp. 986-993 ◽

Cited By ~ 2

Author(s):

C J Kuan ◽

M al-Douahji ◽

S J Shankland

Keyword(s):

Cell Cycle ◽

Diabetic Nephropathy ◽

High Glucose ◽

Mesangial Cell ◽

Kinase Inhibitor ◽

Glomerular Hypertrophy ◽

Glomerular Cell ◽

Cyclin Dependent Kinases ◽

Cell Hypertrophy

High glucose inhibits mesangial cell proliferation in vitro and induces hypertrophy in mesangial cells in culture and in experimental diabetic nephropathy. Cell growth is ultimately controlled at the level of the cell cycle by cell cycle regulatory proteins. Cell cycle progression requires that cyclin-dependent kinases be activated by cyclins. Cyclin kinase inhibitors (CKI) inactivate cyclin-dependent kinases, causing cell cycle arrest. In the current study, high glucose-induced mesangial cell hypertrophy in vitro is shown to be associated with increased levels of the CKI p21, but not p27. In the streptozotocin model of experimental diabetes in the mouse, glomerular hypertrophy was associated with a selective increase in p21 expression, whereas the levels of the CKI p27 and p57 did not change. Unlike many other forms of glomerular injury, diabetic nephropathy was not associated with increased apoptosis. These results support a role for p21 in causing glomerular cell hypertrophy in diabetic nephropathy.

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High glucose enhances microRNA-26a to activate mTORC1 for mesangial cell hypertrophy and matrix protein expression

Cellular Signalling ◽

10.1016/j.cellsig.2015.03.007 ◽

2015 ◽

Vol 27 (7) ◽

pp. 1276-1285 ◽

Cited By ~ 28

Author(s):

Nirmalya Dey ◽

Amit Bera ◽

Falguni Das ◽

Nandini Ghosh-Choudhury ◽

Balakuntalam S. Kasinath ◽

...

Keyword(s):

Protein Expression ◽

High Glucose ◽

Matrix Protein ◽

Mesangial Cell ◽

Cell Hypertrophy

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Hydrophobic motif site-phosphorylated protein kinase CβII between mTORC2 and Akt regulates high glucose-induced mesangial cell hypertrophy

AJP Cell Physiology ◽

10.1152/ajpcell.00266.2015 ◽

2016 ◽

Vol 310 (7) ◽

pp. C583-C596 ◽

Cited By ~ 11

Author(s):

Falguni Das ◽

Nandini Ghosh-Choudhury ◽

Meenalakshmi M. Mariappan ◽

Balakuntalam S. Kasinath ◽

Goutam Ghosh Choudhury

Keyword(s):

High Glucose ◽

Mesangial Cell ◽

Pi3 Kinase ◽

Dependent Manner ◽

Akt Phosphorylation ◽

Cell Hypertrophy ◽

Motif Site ◽

Hydrophobic Motif ◽

Mtorc1 Activation ◽

Constitutively Active

PKCβII controls the pathologic features of diabetic nephropathy, including glomerular mesangial cell hypertrophy. PKCβII contains the COOH-terminal hydrophobic motif site Ser-660. Whether this hydrophobic motif phosphorylation contributes to high glucose-induced mesangial cell hypertrophy has not been determined. Here we show that, in mesangial cells, high glucose increased phosphorylation of PKCβII at Ser-660 in a phosphatidylinositol 3-kinase (PI3-kinase)-dependent manner. Using siRNAs to downregulate PKCβII, dominant negative PKCβII, and PKCβII hydrophobic motif phosphorylation-deficient mutant, we found that PKCβII regulates activation of mechanistic target of rapamycin complex 1 (mTORC1) and mesangial cell hypertrophy by high glucose. PKCβII via its phosphorylation at Ser-660 regulated phosphorylation of Akt at both catalytic loop and hydrophobic motif sites, resulting in phosphorylation and inactivation of its substrate PRAS40. Specific inhibition of mTORC2 increased mTORC1 activity and induced mesangial cell hypertrophy. In contrast, inhibition of mTORC2 decreased the phosphorylation of PKCβII and Akt, leading to inhibition of PRAS40 phosphorylation and mTORC1 activity and prevented mesangial cell hypertrophy in response to high glucose; expression of constitutively active Akt or mTORC1 restored mesangial cell hypertrophy. Moreover, constitutively active PKCβII reversed the inhibition of high glucose-stimulated Akt phosphorylation and mesangial cell hypertrophy induced by suppression of mTORC2. Finally, using renal cortexes from type 1 diabetic mice, we found that increased phosphorylation of PKCβII at Ser-660 was associated with enhanced Akt phosphorylation and mTORC1 activation. Collectively, our findings identify a signaling route connecting PI3-kinase to mTORC2 to phosphorylate PKCβII at the hydrophobic motif site necessary for Akt phosphorylation and mTORC1 activation, leading to mesangial cell hypertrophy.

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