Role of PTEN in TNFα induced insulin resistance.
OBJECTIVE
PTEN may play a reversible role in TNFα induced insulin resistance, which has been linked to obesity-associated insulin resistance (IR).


METHODS
Western blots for PTEN and p-Akt were performed on H-411E liver cells incubated with insulin, TNFα, and in selected experiments VO-OHpic vanadium complex in the presence and absence of PTEN siRNA. Total PTEN was compared to β-actin loading control and p-Akt was compared to total Akt.


RESULTS
Western blot and Real Time RT-PCR experiments showed increased PTEN after TNFα treatment (p = 0.04); slightly decreased PTEN after insulin treatment; and slightly increased PTEN after insulin + TNFα treatment. PTEN siRNA markedly inhibited the TNFα-induced increase in PTEN (p < 0.01) without significantly changing the p-Akt levels. The vanadium complex, exhibiting insulin-like effects, also significantly prevented the TNFα-induced increase in PTEN. Combining insulin and VO-OHpic was additive, providing both proof of concept and insight into mechanism.


CONCLUSIONS
The PTEN increase due to TNFα treatment was reversible by both PTEN siRNA knockdown and VO-OHpic treatment. Thus, PTEN is identified as a potential new therapeutic target for reducing IR in Type 2 DM.
Departments of Medicine and Pharmacology, University of Tennessee Health Science Center, Memphis, TN 38163, USA; Medicine and Research Services, Veterans Association Medical Center, Memphis, TN 38104, USA; Wellcome Trust Medical Research Council Institute of Metabolic Science, Cambridge CB2 0QQ, UK; National Institute of Diabetes & Digestive & Kidney Disease, National Institutes of Health, Bethesda, MD 20892, USA.
David A
DA
Bulger
Medicine and Research Services, Veterans Association Medical Center, Memphis, TN 38104, USA.
Jermaine
J
Conley
Departments of Medicine and Pharmacology, University of Tennessee Health Science Center, Memphis, TN 38163, USA; Medicine and Research Services, Veterans Association Medical Center, Memphis, TN 38104, USA.
Spencer H
SH
Conner
Departments of Medicine and Pharmacology, University of Tennessee Health Science Center, Memphis, TN 38163, USA; Medicine and Research Services, Veterans Association Medical Center, Memphis, TN 38104, USA.
Gipsy
G
Majumdar
Departments of Medicine and Pharmacology, University of Tennessee Health Science Center, Memphis, TN 38163, USA; Medicine and Research Services, Veterans Association Medical Center, Memphis, TN 38104, USA. Electronic address: ssolomon@uthsc.edu.
Solomon S
SS
Solomon
D000818:Animals; D001483:Base Sequence; D045744:Cell Line, Tumor; D017931:DNA Primers; D007333:Insulin Resistance; D008099:Liver / Q000166:cytology / Q000378:metabolism; D051059:PTEN Phosphohydrolase / Q000235:genetics / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D060888:Real-Time Polymerase Chain Reaction; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D017931:DNA Primers; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D051059:PTEN Phosphohydrolase; C487216:Pten protein, rat
Adipocyte; Diabetes; Hepatocytes; Insulin resistance; Obesity