Signal transduction events leading to the spatial and temporal regulation of Dictyostelium discoideum chemotaxis.
)A simplified model depicting the major effectors (in blue) activated by cAMP receptors. Receptor stimulation ultimately gives rise to actin polymerization at the front for propulsion, myosin II assembly at the sides to suppress lateral pseudopod formation, and myosin II assembly also at the rear for retraction. The molecular details leading to the regulation of the lipid phosphatase PTEN, phosphoinositide 3-kinae (PI3K), guanylate cyclase (GC), and adenylate cyclase (AC) by Gbg
are still being elucidated. Ras appears to be directly required for the activation of PI3K, although its role in PI3K localization is not known. Green arrows, enzyme activation; blue arrows, membrane localization; red arrows, product relation; dashed arrow, complex regulations that have yet to be fully established. (Inset image
) Myosin heavy chain (MHC) and actin filament distribution in polarized cells. Cells expressing MHC fused with green fluorescent protein (GFP) were fully differentiated, fixed, and stained with tetramethyl rhodamine isothiocyanate (TRITC)-phalloidin. The MHC-GFP posterior signal appears in green, and the actin filaments in red. Bar, 10 m
m. This figure was reproduced from the Science
Viewpoint by Kimmel and Parent.
A. R. Kimmel, C. A. Parent, Dictyostelium discoideum cAMP chemotaxis pathway.
Sci. STKE (Connections Map), http://stke.sciencemag.org/cgi/cm/CMP_7918. [Specific Pathway]
A. R. Kimmel, C. A. Parent, The signal to move: D. discoideum go orienteering. Science 300, 1525-1527 (2003). [Abstract] [Full Text]
Citation for this figure
A. R. Kimmel, C. A. Parent, Signal transduction events leading to the spatial and temporal regulation of Dictyostelium discoideum chemotaxis. Sci. STKE (Supplement to Connections Maps), http://stke.sciencemag.org/cgi/content/full/sigtrans;CMP_7918/DC2.