| First Author | van den Bos E | Year | 2020 |
| Journal | J Biol Chem | Volume | 295 |
| Issue | 22 | Pages | 7726-7742 |
| PubMed ID | 32332099 | Mgi Jnum | J:295172 |
| Mgi Id | MGI:6458176 | Doi | 10.1074/jbc.RA119.011984 |
| Citation | van den Bos E, et al. (2020) Knockout mouse models reveal the contributions of G protein subunits to complement C5a receptor-mediated chemotaxis. J Biol Chem 295(22):7726-7742 |
| abstractText | G protein-coupled receptor signaling is required for the navigation of immune cells along chemoattractant gradients. However, chemoattractant receptors may couple to more than one type of heterotrimeric G protein, each of which consists of a Galpha, Gbeta, and Ggamma subunit, making it difficult to delineate the critical signaling pathways. Here, we used knockout mouse models and time-lapse microscopy to elucidate Galpha and Gbeta subunits contributing to complement C5a receptor-mediated chemotaxis. Complement C5a-mediated chemokinesis and chemotaxis were almost completely abolished in macrophages lacking Gnai2 (encoding Galphai2), consistent with a reduced leukocyte recruitment previously observed in Gnai2 (-/-) mice, whereas cells lacking Gnai3 (Galphai3) exhibited only a slight decrease in cell velocity. Surprisingly, C5a-induced Ca(2+) transients and lamellipodial membrane spreading were persistent in Gnai2 (-/-) macrophages. Macrophages lacking both Gnaq (Galphaq) and Gna11 (Galpha11) or both Gna12 (Galpha12) and Gna13 (Galpha13) had essentially normal chemotaxis, Ca(2+) signaling, and cell spreading, except Gna12/Gna13-deficient macrophages had increased cell velocity and elongated trailing ends. Moreover, Gnaq/Gna11-deficient cells did not respond to purinergic receptor P2Y2 stimulation. Genetic deletion of Gna15 (Galpha15) virtually abolished C5a-induced Ca(2+) transients, but chemotaxis and cell spreading were preserved. Homozygous Gnb1 (Gbeta1) deletion was lethal, but mice lacking Gnb2 (Gbeta2) were viable. Gnb2 (-/-) macrophages exhibited robust Ca(2+) transients and cell spreading, albeit decreased cell velocity and impaired chemotaxis. In summary, complement C5a-mediated chemotaxis requires Galphai2 and Gbeta2, but not Ca(2+) signaling, and membrane protrusive activity is promoted by G proteins that deplete phosphatidylinositol 4,5-bisphosphate. |
