Host EPAC1 Modulates Rickettsial Adhesion to Vascular Endothelial Cells via Regulation of ANXA2 Y23 Phosphorylation.

INTRODUCTION

Intracellular cAMP receptor exchange proteins directly activated by cAMP 1 () regulate obligate intracellular parasitic bacterium rickettsial adherence to and invasion into vascular endothelial cells (ECs). However, underlying precise mechanism(s) remain unclear. The aim of the study is to dissect the functional role of the signaling pathway during initial adhesion of rickettsiae to EC surfaces.

METHODS

In the present study, an established system that is anatomically based and quantifies bacterial adhesion to ECs in vivo was combined with novel fluidic force microscopy (FluidFM) to dissect the functional role of the signaling pathway in rickettsiae-EC adhesion.

RESULTS

The deletion of the gene impedes rickettsial binding to endothelium in vivo. Rickettsial OmpB shows a host -dependent binding strength on the surface of a living brain microvascular EC (BMEC). Furthermore, ectopic expression of phosphodefective and phosphomimic mutants replacing tyrosine (Y) 23 of in -knock out BMECs results in different binding force to reOmpB in response to the activation of .

CONCLUSIONS

modulates rickettsial adhesion, in association with Y23 phosphorylation of the binding receptor . Underlying mechanism(s) should be further explored to delineate the accurate role of cAMP- system during rickettsial infection.