Figure 7.

Gα₁₃a promotes actin assembly via a PDZ RhoGEF-dependent pathway. (A–D) Nomarski images of live WT embryos (A), embryos overexpressing Gα₁₃a alone (B), embryos overexpressing Gα₁₃a and a dominant-negative mutant zebrafish Arhgef11, ΔDHPH (C), or embryos overexpressing Arhgef11 (D) at 80% epiboly. Bar, 250 µm. (E–H) Confocal z-projection images show phalloidin staining of F-actin. Red and green arrowheads indicate the dcm and the EVL, respectively; pink asterisks show the actin bundles in the yolk. Note the gap between dcm and the EVL, and the lack of actin bundles in embryos coinjected with Gα₁₃a and a ΔDHPH-encoding RNA. VP, vegetal pole. Bars, 100 µm. (I) The percentage of embryos with actin bundles in the embryos expressing Gα₁₃a alone or both Gα₁₃a and ΔDHPH. *, P < 0.05 versus Gα₁₃a. (J) Gα₁₃a interacts with zebrafish Arhgef11. Coimmunoprecipitation was performed on cell extracts from HEK 293 cells transfected with Gα₁₃a or Arhfef11 alone, or with both Gα₁₃a and myc-tagged Arhgef11 forms (WT, dominant-negative mutants lacking the RGS domain [ΔRGS], or lacking the DH and PH domains [ΔDHPH]). Immunoblotting was performed with the indicated antibodies. Error bars represent mean ± SEM.