Krug 2018 Thesis
|Krug KP (2018) Adaptation of metabolism and respiratory chain functions in pulmonary arterial vascular muscle cells under chronic hypoxia: especially considering the cytochrome c oxidase subunit 4 isoform 2. Doctoral Dissertation 136.|
Abstract: Vascular remodeling and cellproliferation are part of the pathogenesis of pulmonary arterial hypertension (PAH). Mitochondria play an important role in disease development, due to their important functions in the regulation of reactive oxygen species (ROS), calcium homeostasis and apoptosis. Last but not least, the mitochondrial tricarboxylic acid cycle forms the hub in cell metabolism and the electron transport chain (ETC) acts as the main producer of adenosine triphosphate (ATP). The aim of this study was to elucidate the hypoxia-induced changes in mitochondrial respiration between normoxic control cells and hypoxic incubated cells with help of a modell of the hypoxia-induced PAH. For this purpose, isolated pulmonary arterial smooth muscle cells (PASMC) were incubates in 1% or 7% oxygen (O2) for 24 and for 48 hours. In addition, the O2 affinity and the respiration of defined complex enzymes of the ETC were investigated. Complementary, the analysis of the messenger ribonucleic acid (mRNA) amount of various proteins of the ETC, the cell metabolism and the mitochondrial ROS metabolism took place. The measurements were carried out after 12, 24 and 48 hours. Finally, this study aimed to investigate whether pharmacological intervention with dichloroacetate (DCA) can prevent hypoxia-induced changes in respiration and mRNA amount.
It could be shown that chronic exposure to hypoxia of 1% O2 leads to reduced respiration and reduced O2 affinity in PASMC. At 7% O2, only respiration was reduced. The activity of cytochrome-c-oxidase (Cox) was reduced only after chronic exposure to 1% O2. After chronic exposure to hypoxia, there were numerous changes in the amount of mRNA, so were glucose transporter (GLUT) 1 and lactate dehydrogenase (LDH) a, as representatives of the cell metabolism increased. Succinate dehydrogenase (SDH) d, Cox8b an especially Cox4i2 were also highly regulated. Furthermore, there was an increase in the amount of mRNA of superoxide dismutase (SOD) 2, as a protein of the ROS metabolism. The apoptosis marker p66 SH2 containing proto-oncogene (SHC) was decreased.
The protein concentration of Cox4i2 was increased after exposure to hypoxia. After administration of the pyruvate dehydrogenase kinase (PDK) 1 inhibitor DCA, the hypoxic effect on Cox but not on the respiration could be inhibited. By administration of DCA, the mRNA of LDHa could be further increased in comparison to hypoxically incubated cells alone. The mRNA of PDK1, Cox4i2 and Cox8b was reduced. In conclusion, DCA could have an antiproliferative effect via a reduction of the lactate level that could possibily be used therapeutically.
• Bioblast editor: Plangger M
Labels: MiParea: Respiration
Stress:Hypoxia Organism: Rat Tissue;cell: Other cell lines Preparation: Intact cells, Permeabilized cells
Coupling state: LEAK, ROUTINE, OXPHOS, ET Pathway: N, S, CIV, ROX HRR: Oxygraph-2k