Porcine somatostatin receptor 2 displays typical pharmacological sst2 features but unique dynamics of homodimerization and internalization

Mario Durán-Prado, Christine Bucharles, Bruno J. Gonzalez, Rafael Vázquez-Martínez, Antonio J. Martínez-Fuentes, Socorro García-Navarro, Simon Rhodes, Hubert Vaudry, María M. Malagón, Justo P. Castaño

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Abstract

Somatostatin (SRIF) exerts its multiple actions, including inhibition of GH secretion and of tumoral growth, through a family of five receptor subtypes (sst1-sst5). We recently reported that an sst2-selective agonist markedly decreases GH release from pig somatotropes, suggesting important roles for this scarcely explored receptor, psst2. Here, functional expression of psst2 in Chinese hamster ovary-K1 and human embryonic kidney-293-AD cell lines was employed to determine its pharmacological features and functional ability to reduce cAMP, and to examine its homodimerization and internalization dynamics in real time in single living cells. Results show that psst2 is a high-affinity receptor (dissociation constant = 0.27 nM) displaying a typical sst2 profile (nM affinity for SRIF-14≥SRIF-28>cortistatin>MK678>octreotide) and high selectivity (EC50 = 1.1 nM) for the sst2 agonist L-779,976, but millimolar or undetectable affinity to other sst-specific agonists (sst3>sst1>sst5⋙sst4). Accordingly, SRIF dose-dependently inhibited forskolin-stimulated cAMP with high potency (EC50 = 6.55 pM) and modest efficacy (maximum 29.1%) via psst2. Cotransfection of human embryonic kidney-293 and Chinese hamster ovary-K1 cells with two receptor constructs modified with distinct fluorescent tags (psst2-YFP/psst2-CFP) enabled fluorescence resonance energy transfer measurement of physical interaction between psst2 receptors and also receptor internalization in single living cells. This revealed that under basal conditions, psst2 forms constitutive homodimers/homomultimers, which dissociate immediately (11 sec) upon SRIF binding. Interestingly, contrary to human sst2, psst2 rapidly reassociates (110.5 sec) during a subsequent process that temporally overlaps with receptor internalization (half-maximal = 95.1 sec). Therefore, psst2 is a potent inhibitory receptor displaying a unique set of interrelated dynamic features of agonist-dependent dimerization, dissociation, internalization, and reassociation, a cascade of events that might be critical for receptor function.

Original languageEnglish
Pages (from-to)411-421
Number of pages11
JournalEndocrinology
Volume148
Issue number1
DOIs
StatePublished - 2007

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Swine
Pharmacology
Cricetulus
Ovary
Fluorescence Resonance Energy Transfer
Octreotide
HEK293 Cells
Dimerization
Colforsin
Somatostatin
Kidney
Growth
somatostatin receptor 2
cortistatin

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

Cite this

Durán-Prado, M., Bucharles, C., Gonzalez, B. J., Vázquez-Martínez, R., Martínez-Fuentes, A. J., García-Navarro, S., ... Castaño, J. P. (2007). Porcine somatostatin receptor 2 displays typical pharmacological sst2 features but unique dynamics of homodimerization and internalization. Endocrinology, 148(1), 411-421. https://doi.org/10.1210/en.2006-0920

Porcine somatostatin receptor 2 displays typical pharmacological sst2 features but unique dynamics of homodimerization and internalization. / Durán-Prado, Mario; Bucharles, Christine; Gonzalez, Bruno J.; Vázquez-Martínez, Rafael; Martínez-Fuentes, Antonio J.; García-Navarro, Socorro; Rhodes, Simon; Vaudry, Hubert; Malagón, María M.; Castaño, Justo P.

In: Endocrinology, Vol. 148, No. 1, 2007, p. 411-421.

Research output: Contribution to journalArticle

Durán-Prado, M, Bucharles, C, Gonzalez, BJ, Vázquez-Martínez, R, Martínez-Fuentes, AJ, García-Navarro, S, Rhodes, S, Vaudry, H, Malagón, MM & Castaño, JP 2007, 'Porcine somatostatin receptor 2 displays typical pharmacological sst2 features but unique dynamics of homodimerization and internalization', Endocrinology, vol. 148, no. 1, pp. 411-421. https://doi.org/10.1210/en.2006-0920
Durán-Prado M, Bucharles C, Gonzalez BJ, Vázquez-Martínez R, Martínez-Fuentes AJ, García-Navarro S et al. Porcine somatostatin receptor 2 displays typical pharmacological sst2 features but unique dynamics of homodimerization and internalization. Endocrinology. 2007;148(1):411-421. https://doi.org/10.1210/en.2006-0920
Durán-Prado, Mario ; Bucharles, Christine ; Gonzalez, Bruno J. ; Vázquez-Martínez, Rafael ; Martínez-Fuentes, Antonio J. ; García-Navarro, Socorro ; Rhodes, Simon ; Vaudry, Hubert ; Malagón, María M. ; Castaño, Justo P. / Porcine somatostatin receptor 2 displays typical pharmacological sst2 features but unique dynamics of homodimerization and internalization. In: Endocrinology. 2007 ; Vol. 148, No. 1. pp. 411-421.
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AU - Martínez-Fuentes, Antonio J.

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