Transferrin receptor functions as a signal-transduction molecule for its own recycling via increases in the internal Ca2+ concentration

Autor: Alain Bienvenüe, Virginie Lafont, Jean R. Philippot, Eve-Isabelle Pécheur, Jean Favero, Josette Sainte-Marie
Přispěvatelé: Institut de biologie et chimie des protéines [Lyon] (IBCP), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Deleage, Gilbert
Jazyk: angličtina
Rok vydání: 1997
Předmět:
Zdroj: European Journal of Biochemistry
European Journal of Biochemistry, Wiley, 1997, 250, pp.689-697
ISSN: 0014-2956
1432-1327
Popis: International audience; Transferrin binding to its receptor modulates transferrin receptor (Tf-R) recycling rates in several cells [Klausner, R. D., Van Renswoude, J., Ashwell, G., Kempf, C., Schechter, A., Dean, A. & Bridges, K. R. (1983a) J. Biol. Chem. 258, 4715-4724; Girones, N. & Davis, R. J. (1989) Biochem. J. 264, 35-46; Sainte-Marie, J., Vidal, M., Bette-Bobillo, P., Philippot, J. R. & Bienvenue, A. (1991) Eur. J. Biochem. 201, 295-302]. To delineate the mechanism of this regulation, we hypothesized that the binding of the ligand to its receptor could lead to activation of several second-messenger pathways, which may redundantly stimulate recycling of the receptor. The effects of different regulators of Ca2+ flux or concentrations were investigated on the Tf-R-recycling pathway; these studies were carried out in two cell types. Perhexiline, a calcium antagonist, slowed receptor recycling in comparison with the control by more than 80% in L2C cells and by 60% in Jurkat cells (B and T lymphoblasts, respectively) but did not affect their internalization rate. Perhexiline thus trapped considerable amounts of Tf-R in the internal compartment. Ca2+ chelators, such as EGTA or 1,2-bis(2-aminophenoxy)ethane-N,N,N,N'-tetraacetic acid, and a Ca2+-channel inhibitor (Ni2+) decreased drastically the recycling rate of Tf-R. Tf-R recycling was shown to be slowed by a calmodulin antagonist. Conversely, artificial elevation of free internal Ca2+ in L2C cells, using lectin, accelerated the recycling rate. These results suggest that the intracellular Ca2+ concentration plays an important role in the outward flow of transferrin receptors. Consequently, we examined the role of transferrin in internal free Ca2+ regulation. The addition of transferrin or anti-(Tf-R) Ig specifically elicited a rise in [Ca2+], as demonstrated by inefficacy of apotransferrin or irrelevant antibodies. These results suggest that Ca2+ is a regulator of Tf-R recycling and that Tf-R seems to function as a signal-transduction molecule (perhaps in conjunction with other membrane proteins) rather than merely as an endocytic receptor.Transferrin binding to its receptor modulates transferrin receptor (Tf-R) recycling rates in several cells [Klausner, R. D., Van Renswoude, J., Ashwell, G., Kempf, C., Schechter, A., Dean, A. & Bridges, K. R. (1983a) J. Biol. Chem. 258, 4715-4724; Girones, N. & Davis, R. J. (1989) Biochem. J. 264, 35-46; Sainte-Marie, J., Vidal, M., Bette-Bobillo, P., Philippot, J. R. & Bienvenue, A. (1991) Eur. J. Biochem. 201, 295-302]. To delineate the mechanism of this regulation, we hypothesized that the binding of the ligand to its receptor could lead to activation of several second-messenger pathways, which may redundantly stimulate recycling of the receptor. The effects of different regulators of Ca2+ flux or concentrations were investigated on the Tf-R-recycling pathway; these studies were carried out in two cell types. Perhexiline, a calcium antagonist, slowed receptor recycling in comparison with the control by more than 80% in L2C cells and by 60% in Jurkat cells (B and T lymphoblasts, respectively) but did not affect their internalization rate. Perhexiline thus trapped considerable amounts of Tf-R in the internal compartment. Ca2+ chelators, such as EGTA or 1,2-bis(2-aminophenoxy)ethane-N,N,N,N'-tetraacetic acid, and a Ca2+-channel inhibitor (Ni2+) decreased drastically the recycling rate of Tf-R. Tf-R recycling was shown to be slowed by a calmodulin antagonist. Conversely, artificial elevation of free internal Ca2+ in L2C cells, using lectin, accelerated the recycling rate. These results suggest that the intracellular Ca2+ concentration plays an important role in the outward flow of transferrin receptors. Consequently, we examined the role of transferrin in internal free Ca2+ regulation. The addition of transferrin or anti-(Tf-R) Ig specifically elicited a rise in [Ca2+], as demonstrated by inefficacy of apotransferrin or irrelevant antibodies. These results suggest that Ca2+ is a regulator of Tf-R recycling and that Tf-R seems to function as a signal-transduction molecule (perhaps in conjunction with other membrane proteins) rather than merely as an endocytic receptor.
Databáze: OpenAIRE
Externí odkaz: