title: [Role of calcium-sensing receptor in hypoxia-induced airway mucous hypersecretion].
abstract: OBJECTIVE
  To explore the mechanism of calcium-sensing receptor (CaSR) in hypoxia-induced airway mucous hypersecretion.
  
  
  METHODS
  Cultured human airway epithelial cells HBE16 by hypoxia incubator (94%N₂, 1%O₂, 5%CO₂, 37 °C). HBE16 were transfected with CaSR targeted small interfering RNA (CaSR-siRNA), pretreated with a specific activator of CaSR CaCl₂ and preincubated with various inhibitors [Gαq/11 protein inhibitor YM-254890, phospholipase C (PLC) inhibitor U73122, inositol 1, 4, 5-triphosphate receptors (IP 3R) inhibitor 2-APB and cell-permeable intracellular calcium chelator BAPTA-AM] before hypoxia. The level of MUC5AC mRNA was detected by reverse transcription-polymerase chain reaction (RT-PCR). And the relative content of CaSR protein was detected by Western blot. The relative content of MUC5AC protein was measured by enzyme-linked immunosorbent assay (ELISA). The intracellular calcium concentration ([Ca²⁺]i) was measured by laser confocal microscopy.
  
  
  RESULTS
  The relative contents of [Ca²⁺]i and MUC5AC protein were obviously higher in hypoxic group ((154.2 ± 11.4) nmol/L, (0.624 ± 0.063) µg/L) than those in control group ((67.5 ± 2.8) nmol/L, (0.257 ± 0.051) µg/L) (all P < 0.01). The relative levels of CaSR protein and MUC5AC mRNA were significantly higher in hypoxic group (0.423 ± 0.028, 0.736 ± 0.045) than those in control group (0.185 ± 0.036, 0.321 ± 0.034) (all P < 0.01). CaCl₂ enhanced the effect of hypoxia. And the results had statistical significances (all P < 0.01). Transfection with CaSR-siRNA significantly decreased the effect of hypoxia (all P < 0.01). Pretreatments with Gαq/11 protein inhibitor, PLC inhibitor, IP 3R inhibitor or intracellular calcium chelator all significantly attenuated the hypoxia-induced MUC5AC hypersecretion and [Ca²⁺]i (all P < 0.05).
  
  
  CONCLUSIONS
  CaSR mediates hypoxia-induced airway mucous hypersecretion through a signaling pathway of Gαq/11/PLC/inositol 1, 4, 5-triphosphate (IP 3)/[Ca²⁺]i.
authors.affiliation: Department of Respiratory Medicine, Second Affiliated Hospital, Chongqing Medical University, Chongqing 400010, China.
authors.forename: Hongju
authors.initials: H
authors.lastname: Yang
authors.forename: M Perelman
authors.initials: MP
authors.lastname: Juliy
authors.forename: P Kolosov
authors.initials: PK
authors.lastname: Victor
authors.affiliation: Email: zxd999@263.net.
authors.forename: Xiangdong
authors.initials: X
authors.lastname: Zhou
mesh_terms: D015687:Cell Hypoxia; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000378:metabolism*; D006801:Humans; D009077:Mucins / Q000378:metabolism*; D044169:Receptors, Calcium-Sensing / Q000378:metabolism*; D012137:Respiratory System / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D009077:Mucins; D044169:Receptors, Calcium-Sensing