Summary
Protein-disulphide isomerase family (PDI) are an ER-stress protein that controls TF-procoagulant
activity but its role in HVSMC migration and coronary artery disease remains to be
elucidated. We aimed to investigate whether in human coronary smooth muscle cells
(HVSMC) the ER-stress protein-disulphide isomerase family A member 2 (PDIA2) regulates
tissue factor (TF) polarisation during migration and atherosclerotic remodeling. PDIA2
and TF were analysed by confocal microscopy, silenced by small interfering RNAs (siRNA)
and their function analysed by transwell and migration assays in vitro and in vivo.
PDIA2and TF co-localise in the front edge of motile HVSMC. Silencing PDIA2, as well
as silencing TF, reduces migration. PDIA2 silenced cells show increased TF-rich microparticle
shedding. In vivo cell-loaded plug implants in nude mice of PDIA2 silenced HVSMC together
with microvascular endothelial cells showed a significant impairment in mature microvessel
formation. PDIA2 and TF are found in remodelled atherosclerotic plaques but not in
healthy coronaries. In conclusion, we demonstrate that TF is chaperoned by PDIA2 to
the HVSMC membrane and to the cell migratory front. Absence of PDIA2 impairs TF intracellular
trafficking to its membrane docking favoring its uncontrolled release in microparticles.
TF-regulated HVSMC migration and microvessel formation is under the control of the
ER-protein PDIA2.
Keywords
Remodelling - angiogenesis - protein disulphide isomerase A2 - tissue factor - microparticle
shedding