This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Rabadan-Diehl, C. Articles by Aguilera, G. Search for Related Content PubMed PubMed Citation Articles by Rabadan-Diehl, C. Articles by Aguilera, G.

Translational Regulation of the Vasopressin V1b Receptor Involves an Internal Ribosome Entry Site

Section on Endocrine Physiology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-1862

Address all correspondence and requests for reprints to: Greti Aguilera, M.D., Section on Endocrine Physiology, Developmental Endocrinology Branch, National Institute of Child Health and Human Development, National Institutes of Health, Building 10, Room 10N262, 10 Center Drive, Mall Stop Code 1862, Bethesda, Maryland 20892-1862. E-mail: Greti_Aguilera{at}nih.gov.

Posttranscriptional mechanisms play an important role regulating pituitary levels of vasopressin V1b receptors (V1bR) during adaptation to stress. This study investigates the involvement of an internal ribosome entry site (IRES) in the 5'untranslated region (5'UTR) on V1bR translation. Transfection of bicistronic luciferase constructs into MCF-7 cells showed marked increases in translation of the second cistron after insertion of a 499-bp fragment of the V1bR 5'UTR in the intercistronic region, independently of cap-mediated translation, indicating the presence of IRES activity. IRES-mediated translation was potentiated by the protein kinase C activators, 12-O-tetradecanoylphorbol 13-acetate (PMA) and bryostatin 1, and appears to involve phosphorylation of amino terminus of eIF4G. In Chinese hamster ovary cells transfected with pV1bR-green fluorescent protein (pV1bR-GFP), PMA increased V1bR-GFP protein levels when cap-mediated translation was inhibited by rapamycin. The effect of PMA was due to increased translation because it persisted under transcriptional blockade by actinomycin D, and it was completely abolished by cycloheximide. In addition, PMA stimulated [³⁵S]methionine incorporation into V1bR-GFP but not ß-actin in the absence of mRNA changes. The data show that regulation of IRES activity in the 5'UTR of the V1bR mRNA probably through phosphorylation of eIF4G may serve as a mechanism for rapid changes in V1bR translation to meet physiological demands.

This article has been cited by other articles:

				S. D. Baird, M. Turcotte, R. G. Korneluk, and M. Holcik Searching for IRES RNA, October 1, 2006; 12(10): 1755 - 1785. [Abstract] [Full Text] [PDF]

				C. J. Lynch, B. Gern, C. Lloyd, S. M. Hutson, R. Eicher, and T. C. Vary Leucine in food mediates some of the postprandial rise in plasma leptin concentrations Am J Physiol Endocrinol Metab, September 1, 2006; 291(3): E621 - E630. [Abstract] [Full Text] [PDF]

				S. Ma, M. J. Shipston, D. Morilak, and J. A. Russell Reduced Hypothalamic Vasopressin Secretion Underlies Attenuated Adrenocorticotropin Stress Responses in Pregnant Rats Endocrinology, March 1, 2005; 146(3): 1626 - 1637. [Abstract] [Full Text] [PDF]