Role of the PI3-kinase signaling pathway in trafficking of the surfactant protein A receptor P63 (CKAP4) on type II pneumocytes
| Autor: | Li Zhang, Jian-Qin Tao, Aron B. Fisher, Altaf S. Kazi, Sheldon I. Feinstein, Sandra R. Bates |
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| Jazyk: | angličtina |
| Rok vydání: | 2010 |
| Předmět: |
Pulmonary and Respiratory Medicine
Physiology Receptors Cell Surface Biology chemistry.chemical_compound Physiology (medical) Cyclic AMP Animals Humans Secretion Phosphatidylinositol Enzyme Inhibitors Protein kinase B Cells Cultured Pulmonary Surfactant-Associated Protein A Kinase Endoplasmic reticulum Type-II Pneumocytes Cell Membrane Membrane Proteins Cell Biology Articles Cell biology Surfactant protein A Rats Enzyme Activation chemistry Biochemistry Alveolar Epithelial Cells Liposomes sense organs Signal transduction Phosphatidylinositol 3-Kinase Proto-Oncogene Proteins c-akt Signal Transduction |
| Popis: | Surfactant protein A (SP-A) plays an important role in the maintenance of lung lipid homeostasis. Previously, an SP-A receptor, P63 (CKAP4), on type II pneumocyte plasma membranes (PM) was identified by chemical cross-linking techniques. An antibody to P63 blocked the specific binding of SP-A to pneumocytes and the ability of SP-A to regulate surfactant secretion. The current report shows that another biological activity of SP-A, the stimulation of surfactant uptake by pneumocytes, is inhibited by P63 antibody. cAMP exposure resulted in enrichment of P63 on the cell surface as shown by stimulation of SP-A binding, enhanced association of labeled P63 antibody with type II cells, and promotion of SP-A-mediated liposome uptake, all of which were inhibited by competing P63 antibody. Incubation of A549 and type II cells with SP-A also increased P63 localization on the PM. The phosphatidylinositol 3-kinase (PI3-kinase) signaling pathway was explored as a mechanism for the transport of this endoplasmic reticulum (ER)-resident protein to the PM. Treatment with LY-294002, an inhibitor of the PI3-kinase pathway, prevented the SP-A-induced PM enrichment of P63. Exposure of pneumocytes to SP-A or cAMP activated Akt (PKB). Blocking either PI3-kinase or Akt altered SP-A-mediated lipid turnover. The data demonstrate an important role for the PI3-kinase-Akt pathway in intracellular transport of P63. The results add to the growing body of evidence that P63 is critical for SP-A receptor-mediated interactions with type II pneumocytes and the resultant regulation of surfactant turnover. |
| Databáze: | OpenAIRE |
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