Summary
Prolonged vascular hyperpermeability is a common feature of many diseases. Vascular
hyperpermeability is typically associated with changes in the expression patterns
of adherens and tight junction proteins. Here, we focus on the less-appreciated contribution
of gap junction proteins (connexins) to basal vascular permeability and endothelial
dysfunction. First, we assess the association of connexins with endothelial barrier
integrity by introducing tools used in connexin biology and relating the findings
to customary readouts in vascular biology. Second, we explore potential mechanistic
ties between connexins and junction regulation. Third, we review the role of connexins
in microvascular organisation and development, focusing on interactions of the endothelium
with mural cells and tissue-specific perivascular cells. Last, we see how connexins
contribute to the interactions between the endothelium and components of the immune
system, by using neutrophils as an example. Mounting evidence of crosstalk between
connexins and other junction proteins suggests that we rethink the way in which different
junction components contribute to endothelial barrier function. Given the multiple
points of connexin-mediated communication arising from the endothelium, there is great
potential for synergism between connexin-targeted inhibitors and existing immune-targeted
therapeutics. As more drugs targeting connexins progress through clinical trials,
it is hoped that some might prove effective at countering vascular hyperpermeability.
Keywords
Connexins - endothelial cells - gap junctions - permeability