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

Doan, Ngoc-Duc; Nguyen, Thi Tuyet Mai; Letourneau, Myriam; Turcotte, Kathy; Fournier, Alain et Chatenet, David ORCID: https://orcid.org/0000-0002-7270-4328 (2012). Biochemical and pharmacological characterization of nuclear urotensin-II binding sites in rat heart British Journal of Pharmacology , vol. 166 , nº 1. pp. 243-257. DOI: 10.1111/j.1476-5381.2011.01710.x.

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Résumé

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.

Type de document:	Article
Mots-clés libres:	urotensin-II; urotensin II-related peptide; nuclear receptors; intracrine; cardiovascular; endocytosis
Centre:	Centre INRS-Institut Armand Frappier
Date de dépôt:	07 mars 2024 16:38
Dernière modification:	07 mars 2024 16:38
URI:	https://espace.inrs.ca/id/eprint/14015

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