TY - JOUR
T1 - Amino acid residues 268-276 of the erythropoietin receptor contain an endocytosis motif and are required for erythropoietin-mediated proliferation
AU - Flint-Ashtamker, Galit
AU - Eisen-Lev, Ronit
AU - Cohen, Jacob
AU - Jun-shen Huang, Lily
AU - Neumann, Drorit
N1 - Funding Information:
We thank Prof. R. Sagi-Eisenberg for critically reviewing the manuscript, Lia Supino-Rosin for many helpful suggestions as well as helping in many practical aspects and Prof. Harvey F. Lodish for enlightening discussions. We gratefully acknowledge the assistance of Eran Barzilay and Mazal Reyna. This work was supported by a Grant from the Israel Science Foundation administered by the Israel Academy of Sciences and Humanities (574/99 18.2) and the Israel Cancer Research Fund (RCDA) to D.N. L.J.H. holds a postdoctoral fellowship from the National Institutes of Health. This work was performed in partial fulfillment of the requirements of an M.Sc. degree for G.F.A. and of Ph.D. degrees for R.E.-L. and J.C.
PY - 2002/5/8
Y1 - 2002/5/8
N2 - Erythropoietin (EPO) promotes viability, proliferation and differentiation of mammalian erythroid progenitor cells via its specific cell surface receptor (EPO-R). We have previously shown that truncated EPO-Rs containing 267 amino acids or less were defective in internalization of 125I-EPO, whereas internalization via a receptor derivative containing 276 amino acids was unaffected, thus directing focus to the nine amino acid residues FEGLFTTHK at positions 268-276 [Levin, Cohen, Supino, Yoshimura, Watowich, Neumann, FEBS Lett. 427 (1998) 164-170]. Here, a panel of EPO-R mutants was generated to determine the role of these residues in EPO endocytosis, down regulation of cell surface receptors and EPO-mediated signaling. While linking amino acid residues 268-276 to a truncated EPO-R (Δ+9 EPO-R) conferred both ligand uptake and ligand-independent down regulation of the respective receptor from the cell surface, Phe 272 was crucial for EPO endocytosis but not for ligand-independent down regulation. Additional receptor motifs probably play a role in EPO endocytosis and receptor down-regulation, as these processes were not adversely impaired in Δ268-276 EPO-R. A central role of residues 268-276, in particular Phe, was demonstrated by the inability of Δ268-276 and F268,272A EPO-Rs to support EPO-mediated signal transduction.
AB - Erythropoietin (EPO) promotes viability, proliferation and differentiation of mammalian erythroid progenitor cells via its specific cell surface receptor (EPO-R). We have previously shown that truncated EPO-Rs containing 267 amino acids or less were defective in internalization of 125I-EPO, whereas internalization via a receptor derivative containing 276 amino acids was unaffected, thus directing focus to the nine amino acid residues FEGLFTTHK at positions 268-276 [Levin, Cohen, Supino, Yoshimura, Watowich, Neumann, FEBS Lett. 427 (1998) 164-170]. Here, a panel of EPO-R mutants was generated to determine the role of these residues in EPO endocytosis, down regulation of cell surface receptors and EPO-mediated signaling. While linking amino acid residues 268-276 to a truncated EPO-R (Δ+9 EPO-R) conferred both ligand uptake and ligand-independent down regulation of the respective receptor from the cell surface, Phe 272 was crucial for EPO endocytosis but not for ligand-independent down regulation. Additional receptor motifs probably play a role in EPO endocytosis and receptor down-regulation, as these processes were not adversely impaired in Δ268-276 EPO-R. A central role of residues 268-276, in particular Phe, was demonstrated by the inability of Δ268-276 and F268,272A EPO-Rs to support EPO-mediated signal transduction.
KW - Endocytosis
KW - Erythropoietin
KW - Erythropoietin receptor
KW - Tyr-phosphorylation
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U2 - 10.1016/S0014-5793(02)02691-1
DO - 10.1016/S0014-5793(02)02691-1
M3 - Article
C2 - 11997044
AN - SCOPUS:0037042229
SN - 0014-5793
VL - 518
SP - 189
EP - 194
JO - FEBS Letters
JF - FEBS Letters
IS - 1-3
ER -