Functional expression of the CXC-chemokine receptor-4/fusin on mouse microglial cells and astrocytes.
The mRNA for the seven-transmembrane-spanning G protein-coupled receptor fusin/CXCR-4 is expressed in primary mouse astrocyte cultures and the transformed mouse microglial cell line, N9. Cell surface expression of fusin in these cells was confirmed by staining with a polyclonal anti-fusin Ab. The functional capacity of this chemokine receptor was examined by evaluating the calcium responses following stimulation of glial cells with the CXC-chemokine, stromal-derived cell factor-1alpha (SDF-1alpha). Both astrocytes and microglial cells mobilized calcium following stimulation with chemically synthesized SDF-1alpha. SDF-1alpha- and carbachol-mediated calcium responses of astrocytes were partially inhibited by treatment with pertussis toxin (PTx), suggesting receptor coupling to a combination of G alpha(i) and other G proteins. In contrast, the calcium responses of microglial cells to SDF-1alpha were completely PTx sensitive, while responses to carbachol stimulation were PTx resistant. The ability of SDF-1alpha to induce glial cell migration was also examined. Synthetic SDF-1alpha was a potent chemoattractant for mouse microglial cells at ligand concentrations of 10 to 500 ng/ml; peak responses were noted at 100 ng/ml. In contrast, astrocytes did not migrate toward a gradient of SDF-1alpha. The failure of SDF-1alpha to induce astrocyte migration was specific, as another chemokine, macrophage inflammatory protein-1alpha, triggered astrocyte chemotaxis.
Tanabe
S
S
Department of Pathology, Harvard Medical School, Boston, MA 02115, USA.
Heesen
M
M
Yoshizawa
I
I
Berman
M A
MA
Luo
Y
Y
Bleul
C C
CC
Springer
T A
TA
Okuda
K
K
Gerard
N
N
Dorf
M E
ME
D000818:Animals; D001253:Astrocytes / Q000378:metabolism* / Q000473:pathology; D002118:Calcium / Q000378:metabolism; D002461:Cell Line, Transformed; D002465:Cell Movement / Q000187:drug effects; D054377:Chemokine CXCL12; D019743:Chemokines, CXC; D016207:Cytokines / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000378:metabolism; D008565:Membrane Proteins / Q000096:biosynthesis*; D051379:Mice; D008807:Mice, Inbred BALB C; D017628:Microglia / Q000378:metabolism* / Q000473:pathology; D019718:Receptors, CXCR4; D015728:Receptors, HIV / Q000096:biosynthesis*
D054377:Chemokine CXCL12; D019743:Chemokines, CXC; C515256:Cxcl12 protein, mouse; D016207:Cytokines; D008565:Membrane Proteins; D019718:Receptors, CXCR4; D015728:Receptors, HIV; D019204:GTP-Binding Proteins; D002118:Calcium