Expression of Soluble Guanylate Cyclase in Rat and Human Hepatocytes

Abstract

Soluble Guanylate Cyclase (sGC) is a key enzyme in the nitric oxide (NO) signaling pathway. sGC binds NO to produce cyclic guanosine-3’,5’-monophosphate (cGMP). The NO-sGC-cGMP pathway is directly involved in a number of physiological functions including smooth muscle vasodilation. Deficiencies in this system, such as reduced NO tone, can result in cardiovascular dysfunction. Stimulators of sGC have been developed to synergize with and enhance NO signaling, creating potential therapies for a number of diseases. Currently, it is known that sGC is expressed in tissues such as the brain, kidney, lung, and liver. However, as an intracellular enzyme, sGC expression in specific cell types within these tissues remains to be explored. This study aims to uncover the expression of sGC in rat and human hepatocyte cells, the major cell type in the liver responsible for metabolizing and detoxifying the body. To begin, the expression of sGC subunits α1 and β1 was assessed by immunohistochemistry (IHC) staining on a paraffin fixed rat liver slice. The results uncovered the localization of sGC in stellate, endothelial and hepatocytes surrounding the vasculature in a rat liver. To confirm positive expression of sGC in hepatocytes, branched DNA (bDNA) probes for sGC were used to confirm expression of sGC in isolated, cryopreserved rat and human hepatocyte cells. Finally, the functionality of the sGC enzyme was shown in vitro by stimulating both rat and human hepatocytes in the presence of an sGC stimulator with and without the NO-donor (DETA). Target engagement by the sGC stimulator was determined through the quantitation of cGMP.