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conferenceseries
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Volume 7, Issue 4 (Suppl)
J Nephrol Ther 2017
ISSN: 2161-0959 JNT, an open access journal
Nephrology & Urology 2017
July 06-07, 2017
JULY 06-07, 2017 KUALA LUMPUR, MALAYSIA
12
TH
ANNUAL CONFERENCE ON
Nephrology & Urology
Ser-660 phosphorylation of protein kinase C beta II ( PKCβII) by mammalian target of rapamycin
complex 2 (mTORC2) regulates high glucose (HG)-induced mesangial cell hypertrophy
F Das, N Ghosh Choudhury, M Mariappan, B S Kasinath and G Ghosh Choudhury
University of Texas Health Science Center, USA
P
rotein kinase C beta II (PKCβII) has been implicated in diabetic nephropathy (DN). Mesangial cell (MC) hypertrophy is a
pathologic feature of DN. PKCβII undergoes phosphorylation at the hydrophobic motif site Ser-660 for its activity. We have
shown that mTOR complex 1 (C1) regulates MC hypertrophy. How activation of PKCβII by Ser-660 phosphorylation fits into
mTOR signaling to control MC hypertrophy is not known. HG significantly increased phosphorylation of PKCβII at Ser-660
in a PI 3 kinase-dependent manner. siRNAs against PKCβII, dominant negative PKCβII and nonphosphorylatable mutant of
PKCβII, PKCβIIS660A, blocked mTORC1 activity due to lack of PRAS40 phosphorylation, resulting in significant inhibition
of HG-induced MC protein synthesis and hypertrophy. Also, PKCβIIS660A attenuated phosphorylation of Akt at Ser-473, a
putative mTOR complex 2 (C2) site. Specific inhibition of mTORC2 by shRNAs against rictor or Sin1, two exclusive and required
components for its activity, suppressed HG-induced phosphorylation of PKCβII Ser-660 and Akt Ser-473, resulting in attenuation
ofmTORC1 activity leading to inhibitionofMChypertrophy. Constitutively active (CA) Akt or CAmTORC1 reversed shRictor- or
shSin1-mediated inhibition of HG-induced MC hypertrophy. Furthermore, CA PKCβII reversed the shRictor- or shSin1 induced
inhibition of HG-stimulated Akt Ser-473 phosphorylation and MC hypertrophy. Finally, we show increased phosphorylation of
PKCβII Ser660, PRAS40 and Akt Ser-473 in association with activation of mTORC1 in renal cortices of OVE26 mice with type 1
diabetes. These results provided the first evidence that HG-induced activation of mTORC2 phosphorylates and activates PKCβII
to increase the phosphorylation of Akt at Ser-473 to finally activate mTORC1 to induce MC hypertrophy. Thus, we uncovered a
specific role of mTORC2 for Akt/mTORC1 activation
via
PKCβII Ser-660 phosphorylation.
dasf@uthscsa.eduJ Nephrol Ther 2017, 7:4 (Suppl)
DOI: 10.4172/2161-0959-C1-043