Dissociation of chemotaxis from agonist-induced receptor internalization in a lymphocyte cell line transfected with CCR2B. Evidence that directed migration does not require rapid modulation of signaling at the receptor level.
To investigate the role of the carboxyl-terminal region (52 amino acids) of the monocyte chemoattractant protein 1 receptor (CCR2B) in chemotaxis, we created a series of mutants and expressed them in a murine pre-B lymphocyte cell line. Truncation of the cytoplasmic carboxyl tail to 20 amino acids had little or no effect on chemotaxis or signal transduction, but further truncation resulted in marked functional defects. Upon incubation with monocyte chemoattractant protein 1, CCR2B underwent rapid and extensive internalization, and this was impaired progressively as the carboxyl tail was truncated from 52 to 8 amino acids. Mutation of all of the serine and threonine residues in the carboxyl tail to alanine also resulted in markedly impaired receptor internalization but did not affect signaling or chemotaxis. We conclude that the membrane-proximal portion of the cytoplasmic carboxyl tail of CCR2B is critically involved in chemotaxis and signal transduction, but neither phosphorylation of carboxyl serines or threonines nor internalization of the receptor is required for robust chemotaxis.
Arai
H
H
Gladstone Institute of Cardiovascular Disease, University of California, San Francisco, California 94141-9100, USA.
Monteclaro
F S
FS
Tsou
C L
CL
Franci
C
C
Charo
I F
IF
D000262:Adenylyl Cyclases / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001402:B-Lymphocytes; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000502:physiology; D018932:Chemokine CCL2 / Q000494:pharmacology*; D002634:Chemotaxis, Leukocyte / Q000187:drug effects; D006801:Humans; D007668:Kidney; D007700:Kinetics; D051379:Mice; D008961:Models, Structural; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D016133:Polymerase Chain Reaction; D017433:Protein Structure, Secondary; D054390:Receptors, CCR2; D019707:Receptors, Chemokine; D018121:Receptors, Cytokine / Q000819:agonists / Q000737:chemistry / Q000502:physiology*; D011994:Recombinant Proteins / Q000819:agonists / Q000096:biosynthesis / Q000737:chemistry; D017384:Sequence Deletion; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014162:Transfection
C515334:CCR2 protein, human; C515335:Ccr2 protein, mouse; D018932:Chemokine CCL2; D054390:Receptors, CCR2; D019707:Receptors, Chemokine; D018121:Receptors, Cytokine; D011994:Recombinant Proteins; D000262:Adenylyl Cyclases; D002118:Calcium