Biochemical and pharmacological characterization of nuclear urotensin-II binding sites in rat heart

Autor: Doan, N. D., Nguyen, T. T. M., Létourneau, M., Turcotte, K., Fournier, Alain, Chatenet, D.
Přispěvatelé: Institut Armand Frappier (INRS-IAF), Institut National de la Recherche Scientifique [Québec] (INRS)-Réseau International des Instituts Pasteur (RIIP), International Associated laboratory Samuel de Champlain, Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut National de la Recherche Scientifique [Québec] (INRS)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Normandie Université (NU), This work was supported by the Canadian Institutes of Health Research
Jazyk: angličtina
Rok vydání: 2012
Předmět:
Zdroj: British Journal of Pharmacology
British Journal of Pharmacology, Wiley, 2012, 166 (1), pp.243-57. ⟨10.1111/j.1476-5381.2011.01710.x⟩
ISSN: 0007-1188
1476-5381
DOI: 10.1111/j.1476-5381.2011.01710.x⟩
Popis: International audience; 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.
Databáze: OpenAIRE
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