Protein kinase A 억제제인 KT5720이 글루카곤 매개성 항산화 효소의 발현감소에 미치는 영향 = Effects of the Protein Kinase A Inhibitor KT5720 on Glucagon-Mediated Decrease in Expression of Antioxidant Enzymes

다국어 초록 (Multilingual Abstract)

We reported previously that glucagon decreased alpha- and pi-class glutathione S-transferases (GSTs) and microsomal epoxide hydrolase (mEN) protein levels in primary cultured rat hepatocytes. The present study examines the effects of Protein kinase A (PKA) inhibitor, KT5720, on the glucagon-mediated decrease in expression of GSTs and mEN. To assess cell viability. lactate dehydrogenase release and MTT activity were examined in hepatocytes treated KT5720. Cell viability was significantly decreased in a concentration dependent manner after incubation with KT5720 at the concentrations of 1 $\mu$M or above for 24 h, which was inhibited by the cytochrome P450 inhibitor SKF-525A. In contrast, another PKA inhibitor H89 (up to 25 $\mu$M) was not toxic to hepatocytes. The glucagon-mediated decrease in expression of alpha- and pi-class GSTs and mEH was completely inhibited by 25 $\mu$M H89 and attenuated by 0.1 $\mu$M KT5720. This study demonstrates that KT5720 may cause cytotoxicity in rat hepatocytes through cytochrome P450-dependent bioactivation. The present study implicates PKA in mediating the inhibitory effect of glucagon on expression of alpha- and pi- class GSTs and mEH.

참고문헌 (Reference)

1 "susceptibility in relation to combined polymorphisms of microsomal epoxide hydrolase and glutathione S-transferase P1" 173 : 155-162, 2001

2 "novel and potent inhibitors of protein kinase C and cyclic nucleotide-dependent protein kinas-es" 142 (142): 436-440, 1987

3 "glia potently protects neurons from oxidative stress" 23 (23): 3394-3406, 2003

4 "The mitogen-activated protein kinase kinase(mek) inhibitor PD98059 elevates primary cultured rat hepatocyte glutathione lev-els independent of inhibiting mek" 34 (34): 683-689, 2006b

5 "TOXICOL" 21 (21): 252-,

6 "Role of oxidative stress in dia-betic complications:a new perspective on an old para-digm" 48 : 1-9, 1999

7 "Role of mechanical and redox stress in activa-tion of mitogen-activated protein kinases in primary cul-tured rat hepatocytes" 70 (70): 1785-1795, 2005

8 "Reduction in endogenous parkin levels renders glial cells sensitive to both caspase-dependent and caspase-independent cell death" 20 (20): 2038-2048, 2004

9 "Polymorphisms of microsomal epoxide hydrolase gene and severity of HCV-related liver dis-ease" 36 : 195-201, 2002

10 "Oxidative stress: Introductory remarks. In: H. Sies, Editor, Oxidative Stress" Academic Press 1-8, 1985

11 "Nonalcoholic steatohepatitis: summary of an AASLD Single Topic Conference" 37 : 1202-1219, 2003

12 "Multiple kinase arrest points in the G1 phase of non-transformed mammalian cells are absent in transformed cells" 89 (89): 8626-8630, 1992

13 "Insulin signaling regulates gamma-glutamylcysteine ligase catalytic subunit expression in primary cultured rat hepatocytes" 311 (311): 99-108, 2004b

14 "Insulin and growth factor signaling: Effects on drug-metabolizing enzymes in Drug metabolism and transport" Humana Press 45-83, 2004a

15 "Insulin and glucagons regulation of glutathione S-transferase expression in primary cultured rat hepatocytes" 305 (305): 353-361, 2003a

16 "Insulin and glucagon signaling in regulation of microsomal epox-ide hydrolase expression in primary cultured rat hepato-cytes" 31 (31): 1260-1268, 2003b

17 "Inhibition of forskolin-induced neurite outgrowth and protein phos-phorylation by a newly synthesized selective inhibitor of cyclic AMP-dependent protein kinase, N-[2-(p-bro-mocinnamylamino)ethyl]-5-isoquinolinesulfonamide(H-89), of PC12D pheochromocytoma cells" 265 (265): 5267-5272, 1990

18 "Identification of the insulin signaling cascade in the regulation of alpha-class glutathione S-transferase expression in primary cultured rat hepatocytes" 316 (316): 1255-1261, 2006a

19 "Glutathione-ascorbic acid antioxidant system in animals" 269 (269): 9397-9400, 1994

20 "Glucagon represses signaling through the mammalian target of rapamycin in rat liver by activating AMP-activated pro-tein kinase" 279 : 54103-54109, 2004

21 "Coordinate regulation of glutathione biosynthesis and release by Nrf2-expressing"

22 "Acetoacetate activation of extracellular signal-regulated kinase 1/2 and p38 mitogen-activated protein kinase in primary cultured rat hepatocytes: role of oxidative stress" 310 (310): 728-736, 2004