PALMITOYLATION OF G‐PROTEIN ALPHAQ IN HYPOXIC PULMONARY HYPERTENSION

Abstract

IntroductionHyperreactivity of thromboxane prostanoind receptor (TP) is a major contributor to persistent pulmonary hypertension of the newborn (PPHN). We previously reported that in hypoxic pulmonary artery smooth muscle cells (PASMCs) TP couples mainly with G‐protein alphaq (Gαq), which undergoes palmitoylation. Palmitoylation is a dynamic, reversible post‐translational modification of the N‐terminal cysteine residues of Gαq, which is required for efficient receptor‐Gαq interaction.ObjectiveTo study the role of Gαq palmitoylation in hypoxic pulmonary hypertension.MethodsPPHN was induced in newborn piglets by exposure to normobaric hypoxia (FiO2 0.10) for 72h; age‐matched normoxic piglets served as controls. Serum deprived primary cultured myocytes from newborn pig (day 0) were placed in hypoxic (10% O2) or normoxic (21% O2) environment for 72h. Palmitoylable cysteine to alanine mutants of Gαq were obtained commercially and transiently transfected in HEK293T cells stably expressing TP. Calcium mobilization to TP stimulation was studied by calcium indicator dyes in hypoxic and normoxic conditions. Metabolic labeling of Gαq by 3H palmitic acid is currently pursued under hypoxia and normoxia.ResultsPretreatment with 2‐BrP decreased the maximum contractile response and calcium mobilization of hypoxic pulmonary artery rings and PASMCs respectively. 2‐BrP had minimal effect on rings and PASMCs from normoxic piglets.ConclusionsPalmitoylation of Gαq could play role in hypoxia‐induced hyperreactivity of TP.Funding:MHRC‐MICH Graduate studentship