Figure 6. Model for CRN7 mediated regulation of phagocytosis and development through major Rac downstream effectors WASP and SCAR, respectively.

In WT cells A) CRN7 regulates actin de-polymerization and prevents phagosome formation (arrow at the tip of the phagocytic cup)⁷,¹², B) CRN7 prevents ‘local’ activation of Rac GTPases by sequestering Rac-GDP and impacts WASP activation, C) CRN7 interacts with WASP and inhibits its activity (phagocytosis), D) CRN7 mediated inhibition of Rac activity affects SCAR activation, E) CRN7 binds to SCAR and affects its activity thereby regulating motility and development. In CRN7 KO cells (corB⁻), absence of CRN7 leads to increased local levels of Rac-GTP. The higher Rac-GTP levels activate WASP resulting in increased phagocytosis. On the other hand loss of CRN7 also results in decreased SCAR activity, which affects motility (decreased) and development (accelerated).