Differential involvement of Galpha16 in CC chemokine-induced stimulation of phospholipase Cbeta, ERK, and chemotaxis.
Chemokines are known to regulate the chemotaxis of leukocytes and play an important role in immunological processes. Chemokine receptors are widely distributed in hematopoietic cells and are often co-localized with the hematopoietic-specific G(16) and its close relative, G(14). Yet, many chemokine receptors utilize pertussis toxin-sensitive G(i) proteins for signaling. Given that both G(16) and G(14) are capable of linking G(i)-coupled receptors to the stimulation of phospholipase Cbeta, we examined the capacity of six CC chemokine receptors (CCR1, CCR2a, CCR2b, CCR3, CCR5 and CCR7) to interact with G(14) and G(16) in a heterologous expression system. Among the CC chemokine receptors tested, CCR1, CCR2b, and CCR3 were capable of mediating chemokine-induced stimulation of phospholipase Cbeta via either G(14) or G(16). The G(14)/G(16)-mediated responses exhibited CC chemokine dose-dependency and were resistant to pertussis toxin (PTX) treatment. In contrast, CCR2a, CCR5 and CCR7 were unable to interact with G(14) and G(16). Under identical experimental conditions, all six CC chemokine receptors were fully capable of inhibiting adenylyl cyclase via G(i) as well as stimulating phospholipase Cbeta via 16z44, a G(16/z) chimera that possesses increased promiscuity toward G(i)-coupled receptors. Moreover, CCR1-mediated ERK1/2 phosphorylation was largely PTX-insensitive in THP-1 monocytic cells that endogenously express Galpha(16). In addition, CCR1 agonist was less efficacious in mediating chemotaxis of THP-1 cells following the knockdown of Galpha(16) by overexpressing siRNA, indicating the participation of Galpha(16) in CCR1-induced cell migration. These results show that different CC chemokine receptors can discriminate against G(14) and G(16) for signal transduction.
Tian
Yaji
Y
Department of Biochemistry, Duke University, Durham, North Carolina 27710, USA.
Lee
Maggie M K
MM
Yung
Lisa Y
LY
Allen
Rodger A
RA
Slocombe
Patrick M
PM
Twomey
Breda M
BM
Wong
Yung H
YH
D000818:Animals; D002460:Cell Line; D018925:Chemokines / Q000494:pharmacology; D002633:Chemotaxis; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051379:Mice; D037342:Pertussis Toxin / Q000494:pharmacology; D054799:Phospholipase C beta / Q000378:metabolism*; D054388:Receptors, CCR / Q000378:metabolism*; D054389:Receptors, CCR1 / Q000378:metabolism; D054390:Receptors, CCR2 / Q000378:metabolism; D054397:Receptors, CCR3 / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction
C515300:CCR1 protein, human; C515351:Ccr3 protein, mouse; D018925:Chemokines; D054388:Receptors, CCR; D054389:Receptors, CCR1; D054390:Receptors, CCR2; D054397:Receptors, CCR3; D011993:Recombinant Fusion Proteins; D037342:Pertussis Toxin; D048049:Extracellular Signal-Regulated MAP Kinases; D054799:Phospholipase C beta; C112631:G protein alpha 16; D043802:GTP-Binding Protein alpha Subunits, Gq-G11