Hypoxia increases pulmonary arterial thromboxane receptor internalization independent of receptor sensitization
| Autor: | Martha Hinton, P.P. Lizotte, Jena Fediuk, Shyamala Dakshinamurti, Nora Nolette, Anurag Singh Sikarwar |
|---|---|
| Rok vydání: | 2014 |
| Předmět: |
Pulmonary and Respiratory Medicine
medicine.medical_specialty Thromboxane Swine media_common.quotation_subject education Myocytes Smooth Muscle Receptors Thromboxane Prostacyclin Biology Pulmonary Artery Endocytosis Persistent Fetal Circulation Syndrome Muscle Smooth Vascular Thromboxane receptor 03 medical and health sciences 0302 clinical medicine Internal medicine Caveolin medicine Animals Humans Pharmacology (medical) Receptor Internalization Protein kinase C 030304 developmental biology media_common 0303 health sciences Biochemistry (medical) Infant Newborn Thromboxanes Epoprostenol Actins Cell Hypoxia Cell biology Endocrinology 030217 neurology & neurosurgery medicine.drug Signal Transduction |
| Zdroj: | Pulmonary pharmacologytherapeutics. 30 |
| ISSN: | 1522-9629 |
| Popis: | Persistent Pulmonary Hypertension of the Newborn (PPHN) is characterized by sustained vasospasm and an increased thromboxane:prostacyclin ratio. Thromboxane (TP) receptors signal via Gαq to mobilize IP 3 and Ca 2+ , causing pulmonary arterial constriction. We have previously reported increased TP internalization in hypoxic pulmonary arterial (PA) myocytes. Serum-deprived PA myocytes were grown in normoxia (NM) or hypoxia (HM) for 72 h. TP localization was visualized in agonist-naive and -challenged NM and HM by immunocytochemistry. Pathways for agonist-induced TP receptor internalization were determined by inhibiting caveolin- or clathrin-mediated endocytosis, and caveolar fractionation. Roles of actin and tubulin in TP receptor internalization were assessed using inhibitors of tubulin, actin-stabilizing or -destabilizing agents. PKA, PKC or GRK activation and inhibition were used to determine the kinase responsible for post-agonist receptor internalization. Agonist-naive HM had decreased cell surface TP, and greater TP internalization after agonist challenge. TP protein did not sort with caveolin-rich fractions. Inhibition of clathrin prevented TP internalization. Both actin-stabilizing and -destabilizing agents prevented TP endocytosis in NM, while normalizing TP internalization in HM. Velocity of TP internalization was unaffected by PKA activity, but PKC activation normalized TP receptor internalization in HM. GRK inhibition had no effect. We conclude that in hypoxic myocytes, TP is internalized faster and to a greater extent than in normoxic controls. Internalization of the agonist-challenged TP requires clathrin, dynamic actin and is sensitive to PKC activity. TP receptor trafficking and signaling in hypoxia are pivotal to understanding increased vasoconstrictor sensitivity. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect