Uno S, Nakamura M, Ohomagari Y, Matsuyama S, Seki T, Ariga T
Department of Nutrition and Physiology, Nihon University College of Bioresource Sciences, 3-34-1 Shimouma, Setagaya-ku, Tokyo 154-8513, Japan.
J Biochem. 1998 May;123(5):806-12. doi: 10.1093/oxfordjournals.jbchem.a022008.
We have performed a comparative study on tPA and PAI-1 mRNA expression in primary cultures of rat hepatocytes and elucidated the possible regulation of these factors by certain hormonal stimulation. The tPA mRNA increased 2- to 4-fold in the presence of cholera toxin (CT), dibutyryl cyclic AMP (dbcAMP), or 3-isobutyl-1-methyl xanthine (IBMX), but slightly decreased in the presence of dexamethasone. The tPA activity was also changed by these agents in a similar fashion. On the contrary, PAI-1 mRNA decreased with CT, dbcAMP, or IBMX, but increased transiently with dexamethasone. From results obtained with cycloheximide, ongoing protein synthesis was judged to be required for both PAI-1 induction with dexamethasone and PAI-1 suppression with IBMX, but not for the tPA induction with IBMX. Dexamethasone exerted opposite regulatory effects on the tPA mRNA expression depending on its concentration: at 10(-8) to 10(-6) M, it suppressed the expression; whereas at 10(-10) M, it elevated the expression.
