Connexin and pannexin (hemi)channels in the liver

The liver was among the first organs in which connexin proteins have been identified. Hepatocytes mainly harbour connexin32, while non-parenchymal liver cells typically produce connexin43. Connexins give raise to hemichannels, which dock with counterparts on adjacent cells to form gap junctions. Both hemichannels and gap junctions provide pathways for communication, namely at the extracellular and intercellular level, respectively. Over the years, hepatocellular gap junctions have been shown to underlie a number of liver-specific functions and to drive liver cell growth. In the last few years, it has become clear that connexin hemichannels are involved in liver cell death, in particular in hepatocyte apoptosis. This also holds true for hemichannels composed of pannexin1, a connexin-like protein recently identified in the liver. Moreover, pannexin1 hemichannels are key players in the regulation of hepatic inflammatory process. The current paper provides a concise overview of the features of connexins, pannexins and their channels in the liver.