QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Sciaudone, M. P. Articles by Freake, H. C. Search for Related Content PubMed PubMed Citation Articles by Sciaudone, M. P. Articles by Freake, H. C.

---

Article

Chelation of Zinc Amplifies Induction of Growth Hormone mRNA Levels in Cultured Rat Pituitary Tumor Cells^{1 ,2}

Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269-4017

⁴To whom correspondence should be addressed.

Zinc is thought to be an integral part of nuclear receptor proteins, stabilizing them in a conformation required for binding to target genes. However, we have recently shown that restriction of zinc availability with a chelator (diethylenetriaminepenta-acetic acid, DTPA) enhances, rather than inhibits, the ability of thyroid hormone to induce growth hormone mRNA expression in GH3 rat pituitary tumor cells. In this report, we have extended these observations by showing that a prolonged (48 h) exposure to DTPA is required to see these effects. The induction by DTPA can be reversed by subsequent addition of zinc, but again, this reversal is slow. A second chelator, EDTA, can also induce growth hormone gene expression in the presence of thyroid hormone, though it is less potent than DTPA. Other agents which act via the nuclear receptor pathway, all-trans and 9-cis retinoic acid, also induce expression of growth hormone mRNA. Addition of DTPA amplifies these effects in a zinc-dependent manner. Thus chelation of zinc potentiates the action of ligands acting via nuclear receptors on growth hormone gene expression. The delayed nature of the response suggests an indirect effect.

KEY WORDS: • zinc • thyroid hormone • retinoic acid • growth hormone • diethylenetriaminepenta-acetic acid • rat pituitary tumor cells

This article has been cited by other articles:

				H. C. Freake, K. E. Govoni, K. Guda, C. Huang, and S. A. Zinn Actions and Interactions of Thyroid Hormone and Zinc Status in Growing Rats J. Nutr., April 1, 2001; 131(4): 1135 - 1141. [Abstract] [Full Text]

				R. B. Eckhardt Genetic Research and Nutritional Individuality J. Nutr., February 1, 2001; 131(2): 336S - 339. [Abstract] [Full Text]