A review of the current state of pannexin channels as they relate to the blood vessel wall

Abstract

Pannexin proteins comprise a family of channels whose sole function, to date, is the release of nucleotides (e.g., adenosine 5'-triphosphate [ATP] and uridine 5′-triphosphate [UTP]). With purinergic signaling being such a prevalent form of cellular communication, it is hard to image why a channel dedicated to the release of nucleotides has not been previously identified. However, with their topography and discovery being lumped with the gap junction field (i.e., connexin), they were thought for a long time to be more similar to connexin-based proteins. It is now known that there is a distinct difference between pannexins and connexins. Unlike connexin hemichannels (undocked gap junctions), pannexins can open under physiological Ca2+ levels. With their distribution being nearly ubiquitous across the vasculature and importance of purinergic signaling in the vasculature, it is easy to see why pannexin channels may be, especially, important. In this mini-review, we highlight what we know about the cell biology of pannexins, followed closely by what is known about pannexins in the vasculature in regards to its importance in vascular physiology.