The goals of this project are evaluate the roles of the sexually differentiated pituitary growth hormone secretory pattern (GHSP), and of other hormones, in the regulation of multiple hepatic genes in the rat, and to clone cDNAs and genomic genes for hepatic mRNAs regulated by the GHSP. This will constitute a major step towards the elucidation of the molecular mechanism(s) of growth hormone action in the liver. The GHSP is distinguished by a highly regular pulsatile rhythm in males, and a more continuous, irregular pattern in females. Several sex-dependent hepatic gene products are regulated by the sexually differentiated GHSP, including two isozymes of cytochrome P-450 (h and i) for which I have cloned cDNAs. Various lines of evidence indicate that although the GHSP has a major role in regulation of these function, other hormones also control the expression of at least some of them.
One specific aim of this project is to evaluate the relative roles of the GHSP and other hormones in regulation of sexually differentiated hepatic gene expression, using P-450h and i as a model. The roles of glucocorticoids and thyroid hormones will be investigated in vivo by administering them to hypophysectomized rats, alone or in combination with growth hormone. The molecular level at which these hormones act will be investigated by measuring hormone effects on the hepatic proteins, their mRNAs, and the rates of nuclear transcription of their genes. Similarly, the role of insulin will be evaluated using a streptozotocin diabetes model. The modulation of P-450h and i during acute inflammatory stress, and the humoral factors involved, will also be examined. Another aim is to clone cDNAs and genomic genes for multiple hepatic GHSP-regulated mRNAs using a hybridization-subtraction method to obtain cDNA libraries and probes enriched for such sequences. The possibility that P- 450 isozyme DEa is GHSP-regulated will be studied by purifying it by a published method, preparing specific antibodies to it, and by cloning its cDNA. It is anticipated that the cloned GHSP- responsive genes and their 5'-flanking regions will be valuable and essential tools in the gaining a better understanding of the mechanism of action of this important hormone, and of peptide hormones in general.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
First Independent Research Support & Transition (FIRST) Awards (R29)
Project #
5R29DK039968-02
Application #
3463303
Study Section
Endocrinology Study Section (END)
Project Start
1988-05-01
Project End
1993-04-30
Budget Start
1989-05-01
Budget End
1990-04-30
Support Year
2
Fiscal Year
1989
Total Cost
Indirect Cost
Name
Emory University
Department
Type
Schools of Medicine
DUNS #
042250712
City
Atlanta
State
GA
Country
United States
Zip Code
30322
Morgan, E T; Thomas, K B; Swanson, R et al. (1994) Selective suppression of cytochrome P-450 gene expression by interleukins 1 and 6 in rat liver. Biochim Biophys Acta 1219:475-83
Ferguson, N L; Donahue, B S; Tenney, K A et al. (1993) Pretranslational induction of CYP4A subfamily gene products in diabetic rats and reversal by oral vanadate treatment. Drug Metab Dispos 21:745-6
Morgan, E T (1993) Down-regulation of multiple cytochrome P450 gene products by inflammatory mediators in vivo. Independence from the hypothalamo-pituitary axis. Biochem Pharmacol 45:415-9
Wright, K; Morgan, E T (1991) Regulation of cytochrome P450IIC12 expression by interleukin-1 alpha, interleukin-6, and dexamethasone. Mol Pharmacol 39:468-74
Morgan, E T (1991) Suppression of P450IIC12 gene expression and elevation of actin messenger ribonucleic acid levels in the livers of female rats after injection of the interferon inducer poly rI.poly rC. Biochem Pharmacol 42:51-7
Donahue, B S; Skottner-Lundin, A; Morgan, E T (1991) Growth hormone-dependent and -independent regulation of cytochrome P-450 isozyme expression in streptozotocin-diabetic rats. Endocrinology 128:2065-76
Wright, K; Morgan, E T (1990) Transcriptional and post-transcriptional suppression of P450IIC11 and P450IIC12 by inflammation. FEBS Lett 271:59-61
Morgan, E T; Norman, C A (1990) Pretranslational suppression of cytochrome P-450h (IIC11) gene expression in rat liver after administration of interferon inducers. Drug Metab Dispos 18:649-53
Morgan, E T (1989) Suppression of constitutive cytochrome P-450 gene expression in livers of rats undergoing an acute phase response to endotoxin. Mol Pharmacol 36:699-707