Essential diurnal Rac1 activation during retinal phagocytosis requires αvβ5 integrin but not tyrosine kinases focal adhesion kinase or Mer tyrosine kinase.

ABSTRACT: Diurnal phagocytosis of shed photoreceptor outer-segment particles by retinal pigment epithelial (RPE) cells belongs to a group of conserved clearance mechanisms employing αv integrins upstream of tyrosine kinases and Rho GTPases. In this study, we tested the interdependence of the tyrosine kinases focal adhesion kinase (FAK) and Mer tyrosine kinase (MerTK) and Rho GTPases during engulfment. RPE cells activated and redistributed Rac1, but not RhoA or Cdc42, during phagocytosis. Toxin B, overexpression of dominant-negative Rac1, or decreasing Rac1 expression prevented particle engulfment. Fluorescence microscopy showed that Rac1 inhibition had no obvious effect on F-actin arrangement in resting RPE but prevented recruitment of F-actin to surface-bound phagocytic particles. Quantification of

SUBMITTER: Mao Y 

PROVIDER: S-EPMC3302737 | biostudies-literature | 2012 Mar

REPOSITORIES: biostudies-literature