| Autor: |
Sykes, David A, Riddy, Darren M, Stamp, Craig, Bradley, Michelle E, McGuiness, Neil, Sattikar, Afrah, Guerini, Danilo, Rodrigues, Ines, Glaenzel, Albrecht, Dowling, Mark R, Mullershausen, Florian, Charlton, Steven J |
| Předmět: |
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| Zdroj: |
British Journal of Pharmacology; Nov2014, Vol. 171 Issue 21, p4797-4807, 11p |
| Abstrakt: |
Background and Purpose The molecular mechanism underlying the clinical efficacy of FTY720- P is thought to involve persistent internalization and enhanced degradation of the S1P1 receptor subtype ( S1P1R). We have investigated whether receptor binding kinetics and β-arrestin recruitment could play a role in the persistent internalization of the S1P1R by FTY720- P. Experimental Approach [3 H]- FTY720- P and [33 P]- S1P were used to label CHO- S1P1/ 3Rs for binding studies. Ligand efficacy was assessed through [35 S]- GTPγ S binding and β-arrestin recruitment. Metabolic stability was evaluated using a bioassay measuring intracellular Ca2+ release. CHO- S1P1/ 3R numbers were determined, following FTY720- P treatment using flow cytometry. Key Results The kinetic off-rate of [3 H]- FTY720- P from the S1P1R was sixfold slower than from the S1P3R, and comparable to [33 P]- S1P dissociation from S1P1/ 3Rs. S1P and FTY720- P stimulated [35 S]- GTPγ S incorporation to similar degrees, but FTY720- P was over 30-fold less potent at S1P3Rs. FTY720- P stimulated a higher level of β-arrestin recruitment at S1P1Rs, 132% of the total recruited by S1P. In contrast, FTY720- P was a weak partial agonist at S1P3R, stimulating just 29% of the total β-arrestin recruited by S1P. Internalization experiments confirmed that cell surface expression of the S1P1R but not the S1P3R was reduced following a pulse exposure to FTY720- P, which is metabolically stable unlike S1P. Conclusions and Implications FTY720- P and S1P activation of the S1P1R results in receptor internalization as a consequence of an efficient recruitment of β-arrestin. The combination of slow off-rate, efficacious β-arrestin recruitment and metabolic stability all contribute to FTY720- P's ability to promote prolonged S1P1R internalization and may be critical factors in its efficacy in the clinic. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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