Role of protein kinase D1 in pulmonary hypertension in rats

Abstract

Protein kinase D (PKD) is known to be implicated in a variety of physiological functions and pathological conditions including cardiovascular diseases, such as cardiac hypertrophy and ischemia reperfusion injury. PKD has been thought to be a new target of the diseases for treatments. Previously, we showed that PKD played a role in pulmonary arterial contraction through MYPT1 phosphorylation and actin polymerization and that inhibition of PKD activity decreased right cardiac ventricular pressure in monocrotaline‐induced pulmonary hypertension (PH) model,. In this study, we further investigated a precise role of PKD in PH and in human pulmonary smooth muscle cells (HPSMCs).Material and methodsEight‐week‐old male rats were given either 60 mg/kg MCT or saline 4 weeks before experiments. Isometric tension was measured using pulmonary arterial ring samples to examine the effect of PKD inhibitor, CRT0066101 on norepinephrine (NE)‐induced contraction and phosphorylation of PKD, myosin phosphatase target subunit 1 (MYPT1), regulatory myosin light chain (RLC) and other PKD substrate proteins. Expression of PKD and phosphorylated‐PKD in rats lungs were also examined with immunohistochemistry using anti‐phospho‐PKD antibodies. We also investigated precise roles of PKD isoforms using HPSMCs with RNA interference.ResultsIn pulmonary arterial rings, basal expression of PKD1 and phosphorylated PKD were increased in pulmonary arteries in PH rats. NE increased phosphorylation of PKD, MYPT1 and RLC in ring samples during contraction, which were attenuated by pretreatment of CRT0066101. In immunohistochemistry, increased expression of PKD1 was observed in pulmonary arteries in PH rats (Fig 1). In HASMCs, increased phosphorylation of MYPT1 and RLC with NE were significantly inhibited by PKD1 but not PKD2, 3 knock down.ConclusionsPKD1 may play role in contraction of pulmonary arteries and at least partially via MYPT1 phosphorylation. Increased PKD1 could be involved in PH development in rats.Support or Funding InformationGrant‐in‐Aid for Scientific Research (C) 17K11058Immunohistochemistry with anti‐PKD antibody in lung tissue from PH rats.Figure 1