Pyridine (PY) is present in coal tar, tobacco smoke, roasted coffee and creosote oil. PY inhalation has been reported to increase liver:body weight ratios in rats and to produce fatty degeneration of the liver; oral administration of PY to rats caused hepatic necrosis and the appearance of hepatic nodules. Research in our laboratories has shown PY to be a potent inducer of cytochromes P-450 in nasal, hepatic and renal tissues following inhalation exposure or i.p. administration. Western blot analysis shows P450IIE1 to be one of the major forms induced in these tissues and this form is the low KM PY N-oxidase. Preliminary data reveal no increase in hybridization P450IIE1 mRNA levels in total RNA isolated from hepatic tissues as evidence by Northern or dot blot analysis following PY treatment. In contrast, Northern or dot blot analysis reveals a rapid time-dependent loss of P450IIE1 poly (A)+ mRNA in hepatic tissue following PY treatment. This decrease in poly(A)+ mRNA is attributed to a loss of the poly(A)+ tail and is associated with early posttranscriptional events (increased translational efficiency) of P450IIE1 induction. Moreover, immunocytochemistry shows the presence of P450IIE1 in the nasal """"""""transition zone"""""""" and initial data suggest that PY may be per- oxisome proliferator. Thus, research is proposed to examine two hypotheses: (1) that P450IIE1 exhibits a unique substrate specificity in the oxidation of certain N and S atoms in xenobiotics, and (2) that PY induction of P450IIE1 occurs by posttranscriptional events, i.e. by increased translational efficiency which results in increased protein synthesis, whereas simultaneous induction of P450IIE1 and IA2 by PY is mediated by both transcriptional activation and posttranscriptional events. The specific objectives include: studies on the substrate specificity of P450IIE1 toward N- and S- containing xenobiotics, immunohistochemical studies on PY induction of P450 in nasal tissue including examination of P450IIE1, IA1 and IA2 mRNA in situ; and examination of the role of transcriptional and posttranscriptional regulation of P450IIE1, IA1 and IA2 in nasal, hepatic and renal tissue. Northern and dot blot analysis of mRNA and poly(A)+ mRNA, nuclear run-off assays, cell free translation of poly(A)+ mRNA, analysis of poly(A)+ tail length, mRNA ribosomal content, the levels of polysome-bound and free mRNA and the rate of P-450 protein synthesis in the presence and absence of cyclohexamide and actinomycin D following PY treatment will be accomplished with the goal of elucidating posttranscriptional regulatory pathways in the induction of P450s by PY.

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Shukla, Upasana; Tumma, Nithin; Gratsch, Theresa et al. (2013) Insights into insulin-mediated regulation of CYP2E1: miR-132/-212 targeting of CYP2E1 and role of phosphatidylinositol 3-kinase, Akt (protein kinase B), mammalian target of rapamycin signaling in regulating miR-132/-212 and miR-122/-181a expression in pri Drug Metab Dispos 41:1769-77
Hudder, Alice; Novak, Raymond F (2008) miRNAs: effectors of environmental influences on gene expression and disease. Toxicol Sci 103:228-40
Kim, Sang K; Novak, Raymond F (2007) The role of intracellular signaling in insulin-mediated regulation of drug metabolizing enzyme gene and protein expression. Pharmacol Ther 113:88-120
Kim, Sang K; Abdelmegeed, Mohamed A; Novak, Raymond F (2006) Identification of the insulin signaling cascade in the regulation of alpha-class glutathione S-transferase expression in primary cultured rat hepatocytes. J Pharmacol Exp Ther 316:1255-61
Kim, Sang K; Abdelmegeed, Mohamed A; Novak, Raymond F (2006) The mitogen-activated protein kinase kinase (mek) inhibitor PD98059 elevates primary cultured rat hepatocyte glutathione levels independent of inhibiting mek. Drug Metab Dispos 34:683-9
Abdelmegeed, Mohamed A; Carruthers, Nicholas J; Woodcroft, Kimberley J et al. (2005) Acetoacetate induces CYP2E1 protein and suppresses CYP2E1 mRNA in primary cultured rat hepatocytes. J Pharmacol Exp Ther 315:203-13
Kim, Sang K; Woodcroft, Kimberley J; Oh, Soo Jin et al. (2005) Role of mechanical and redox stress in activation of mitogen-activated protein kinases in primary cultured rat hepatocytes. Biochem Pharmacol 70:1785-95
Abdelmegeed, Mohamed A; Kim, Sang K; Woodcroft, Kimberley J et al. (2004) Acetoacetate activation of extracellular signal-regulated kinase 1/2 and p38 mitogen-activated protein kinase in primary cultured rat hepatocytes: role of oxidative stress. J Pharmacol Exp Ther 310:728-36
Kim, Sang K; Woodcroft, Kimberley J; Khodadadeh, Sarah S et al. (2004) Insulin signaling regulates gamma-glutamylcysteine ligase catalytic subunit expression in primary cultured rat hepatocytes. J Pharmacol Exp Ther 311:99-108
Kim, Sang K; Woodcroft, Kimberley J; Kim, Sang G et al. (2003) Insulin and glucagon signaling in regulation of microsomal epoxide hydrolase expression in primary cultured rat hepatocytes. Drug Metab Dispos 31:1260-8

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