Fig. 5

CXCR7 Does Not Activate Major Pathways Downstream to Chemokine Signaling (A) CXCR7 depletion does not alter calcium levels in the cytosol of somatic cells in control and CXCR7-depleted embryos (p > 0.1, t test). n signifies the number of cells examined. Error bars represent SEM. a.u., arbitrary units. (B) CXCR7 knockdown phenotype is not caused by absence of PI3K function. Shown are PGCs expressing DsRed (red) migrating in embryos globally expressing Akt-PH-EGFP. Migration was monitored in CXCR7-depleted embryos and compared with the migration of PGCs in embryos in which PI3K was inhibited. In CXCR7-depleted embryos PGCs display multiple protrusions in opposing directions (upper panel, arrowheads), typical of CXCR7 inhibition. By contrast, PGCs treated with the selective PI3K inhibitor Wortmannin (25 μM) are polar and migrate with the protrusions, forming in the direction of migration (lower panel, arrowheads). Effective inhibition of PI3K function was monitored by the localization of Akt-PH-EGFP. In DMSO-treated embryos (upper panel), the PH domain localizes to the plasma membrane, whereas PI3K inhibition by Wortmannin induces translocation of the sensor to the cytosol (lower panel). Movies of control cells not treated with the drug and cells in CXCR7-depleted embryos treated with Wortmannin are provided in Movies S8 and S9, respectively. (C) Germ cell-specific expression of CXCR7 does not substitute for CXCR4b function. CXCR7 expression does not revert the effect of CXCR4b-deficient fish (gray bars), but rescues CXCR7 morpholino-treated embryos (white bar). n signifies the number of embryos examined. Error bars represent SEM.