Impact of the liver-specific expression of SHIP2 (SH2-containing inositol 5'-phosphatase 2) on insulin signaling and glucose metabolism in mice.
We investigated the role of hepatic SH2-containing inositol 5'-phosphatase 2 (SHIP2) in glucose metabolism in mice. Adenoviral vectors encoding wild-type SHIP2 (WT-SHIP2) and a dominant-negative SHIP2 (DeltaIP-SHIP2) were injected via the tail vein into db/+m and db/db mice, respectively. Four days later, amounts of hepatic SHIP2 protein were increased by fivefold. Insulin-induced phosphorylation of Akt in liver was impaired in WT-SHIP2-expressing db/+m mice, whereas the reduced phosphorylation was restored in DeltaIP-SHIP2-expressing db/db mice. The abundance of mRNA for glucose-6-phosphatase (G6Pase) and PEPCK was increased, that for glucokinase (GK) was unchanged, and that for sterol regulatory element-binding protein 1 (SREBP)-1 was decreased in hepatic WT-SHIP2-overexpressing db/+m mice. The increased expression of mRNA for G6Pase and PEPCK was partly suppressed, that for GK was further enhanced, and that for SREBP1 was unaltered by the expression of DeltaIP-SHIP2 in db/db mice. The hepatic expression did not affect insulin signaling in skeletal muscle and fat tissue in both mice. After oral glucose intake, blood glucose levels and plasma insulin concentrations were elevated in WT-SHIP2-expressing db/+m mice, while elevated values were decreased by the expression of DeltaIP-SHIP2 in db/db mice. These results indicate that hepatic SHIP2 has an impact in vivo on the glucose metabolism in both physiological and diabetic states possibly by regulating hepatic gene expression.
Department of Internal Medicine, Toyama Medical & Pharmaceutical University, 2630 Sugitani, Toyama, 930-0194, Japan.
Kazuhito
K
Fukui
Tsutomu
T
Wada
Syota
S
Kagawa
Kiyofumi
K
Nagira
Mariko
M
Ikubo
Hajime
H
Ishihara
Masashi
M
Kobayashi
Toshiyasu
T
Sasaoka
D000818:Animals; D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D018014:Gene Transfer Techniques; D005822:Genetic Vectors; D005941:Glucokinase / Q000235:genetics / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D005952:Glucose-6-Phosphatase / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000494:pharmacology*; D020738:Leptin / Q000172:deficiency / Q000235:genetics; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D000072183:Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics* / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects; D051780:Sterol Regulatory Element Binding Protein 1; D014157:Transcription Factors
D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D007328:Insulin; D020738:Leptin; D012333:RNA, Messenger; C497387:SREBF1 protein, human; C497388:Srebf1 protein, mouse; C497389:Srebf1 protein, rat; D051780:Sterol Regulatory Element Binding Protein 1; D014157:Transcription Factors; D005941:Glucokinase; D010744:Phosphoric Monoester Hydrolases; C098706:INPPL1 protein, human; D000072183:Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases; D005952:Glucose-6-Phosphatase; D005947:Glucose