Both authors contributed equally to the work.
Biochemical and pharmacological characterization of nuclear urotensin-II binding sites in rat heart
Version of Record online: 10 APR 2012
© 2011 The Authors. British Journal of Pharmacology © 2011 The British Pharmacological Society
British Journal of Pharmacology
Special Issue: Themed Section: Secretin Family (Class B) G Protein-Coupled Receptors - from Molecular to Clinical Perspectives. Guest Editors: David R Poyner and Debbie L Hay
Volume 166, Issue 1, pages 243–257, May 2012
How to Cite
Doan, N., Nguyen, T., Létourneau, M., Turcotte, K., Fournier, A. and Chatenet, D. (2012), Biochemical and pharmacological characterization of nuclear urotensin-II binding sites in rat heart. British Journal of Pharmacology, 166: 243–257. doi: 10.1111/j.1476-5381.2011.01710.x
- Issue online: 10 APR 2012
- Version of Record online: 10 APR 2012
- Accepted manuscript online: 1 NOV 2011 06:47AM EST
- Received; 21 March 2011; Revised; 12 August 2011; Accepted; 17 September 2011
- urotensin II-related peptide;
- nuclear receptors;
BACKGROUND AND PURPOSE During the past decade, a few GPCRs have been characterized at the nuclear membrane where they exert complementary physiological functions. In this study, we investigated (1) the presence of a functional urotensin-II (U-II) receptor (UT) in rat heart nuclear extracts and (2) the propensity of U-II and U-II-related peptide (URP) to cross the plasma membrane in a receptor-independent manner.
EXPERIMENTAL APPROACH Biochemical and pharmacological methods including competitive binding assays, photoaffinity labelling, immunoblotting as well as de novo RNA synthesis were used to characterize the presence of functional UT receptors in rat heart nuclei. In addition, confocal microscopy and flow cytometry analysis were used to investigate the cellular uptake of fluorescent U-II and URP derivatives.
KEY RESULTS The presence of specific U-II binding sites was demonstrated in rat heart nuclear extracts. Moreover, such subcellular localization was also observed in monkey heart extracts. In vitro transcription initiation assays on rat, freshly isolated, heart nuclei suggested that nuclear UT receptors are functional, and that U-II, but not URP, participates in nuclear UT-associated gene expression. Surprisingly, hU-II and URP efficiently crossed the plasma membrane in a receptor-independent mechanism involving endocytosis through caveolin-coated pits; this uptake of hU-II, but not that of URP, was dependent on extracellular pH.
CONCLUSION Our results suggest that (1) U-II and URP can differentially modulate nuclear UT functions such as gene expression, and (2) both ligands can reach the internal cellular space through a receptor-independent mechanism.