The G protein beta3 subunit splice variant Gbeta3-s causes enhanced chemotaxis of human neutrophils in response to interleukin-8.
A C825T polymorphism was recently described in GNB3, the gene encoding the Gbeta3 subunit of heterotrimeric G proteins. The 825T allele is associated with the expression of a shorter splice variant (Gbeta3-s) and enhanced signal transduction via pertussis toxin (PTX)-sensitive G proteins. Given the pivotal role of G protein betagamma dimers in chemotaxis, we related the genotype at the GNB3 locus as a marker for Gbeta3-s expression to chemotaxis of human neutrophils in response to stimulation with interleukin-8 (IL-8). IL-8, which activates a CXC receptor coupled to PTX-sensitive G proteins, induced at 10 nM an enhanced maximum chemotaxis of neutrophils from individuals with TC/TT genotype compared to CC genotype. Furthermore, migration of neutrophils from 825T allele carriers was 2.5-fold higher at 0.1 nM and 1 nM IL-8. At these concentrations of IL-8, no significant chemotaxis was observed in neutrophils from homozygous C825 allele carriers, indicating a genotype-dependent, different potency of IL-8 to chemoattract neutrophils. In contrast, IL-8-induced Ca2+ signals and O2- generation were independent of genotype. The role of Gbeta3-s in enhanced chemotaxis could be confirmed by determination of chemotaxis of COS-7 cells following transfection with either Gbeta3-s or "wild-type" Gbeta3. Upon stimulation of the transfected cells with the chemoattractant lysophosphatidic acid (LPA), we observed an enhanced chemotactic response of Gbeta3-s-transfected compared to Gbeta3-transfected COS-7 cells, confirming that Gbeta3-s actually causes enhanced chemotaxis.
Virchow
S
S
Institut für Pharmakologie, Universitätsklinikum Essen, Germany. sebastian.virchow@uni-essen.de
Ansorge
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N
Rosskopf
D
D
Rübben
H
H
Siffert
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W
D000483:Alleles; D017398:Alternative Splicing; D000818:Animals; D000838:Anions; D019556:COS Cells; D002118:Calcium / Q000378:metabolism; D002630:Chemotactic Factors / Q000494:pharmacology*; D002634:Chemotaxis, Leukocyte / Q000235:genetics*; D019204:GTP-Binding Proteins / Q000235:genetics*; D006801:Humans; D066298:In Vitro Techniques; D016209:Interleukin-8 / Q000494:pharmacology*; D008246:Lysophospholipids / Q000494:pharmacology; D009504:Neutrophils / Q000502:physiology*; D010100:Oxygen / Q000378:metabolism; D014162:Transfection
D000838:Anions; D002630:Chemotactic Factors; D016209:Interleukin-8; D008246:Lysophospholipids; D019204:GTP-Binding Proteins; D010100:Oxygen; D002118:Calcium