Airway Ciliary Beating Affected by the Pcp4 Dose-Dependent [Ca 2+] i Increase in Down Syndrome Mice, Ts1Rhr

Int J Mol Sci. 2020 Mar 12;21(6):1947. doi: 10.3390/ijms21061947.

Abstract

In Ts1Rhr, a Down syndrome model mouse, the airway ciliary beatings are impaired; that is, decreases in ciliary beat frequency (CBF) and ciliary bend angle (CBA, an index of ciliary beat amplitude)). A resumption to two copies of the Pcp4 gene on the Ts1Rhr trisomic segment (Ts1Rhr:Pcp4+/+/-) rescues the decreases in CBF and CBA that occur in Ts1Rhr. In airway cilia, upon stimulation with procaterol (a β2-agonist), the CBF increase is slower over the time course than the CBA increase because of cAMP degradation by Ca2+/calmodulin-dependent phosphodiesterase 1 (PDE1) existing in the metabolon regulating CBF. In Ts1Rhr, procaterol-stimulated CBF increase was much slower over the time course than in the wild-type mouse (Wt) or Ts1Rhr:Pcp4+/+/-. However, in the presence of 8MmIBMX (8-methoxymethyl isobutylmethyl xanthine, an inhibitor of PDE1) or calmidazolium (an inhibitor of calmodulin), in both Wt and Ts1Rhr, procaterol stimulates CBF and CBA increases over a similar time course. Measurements of cAMP revealed that the cAMP contents were lower in Ts1Rhr than in Wt or in Ts1Rhr:Pcp4+/+/-, suggesting the activation of PDE1A that is present in Ts1Rhr airway cilia. Measurements of the intracellular Ca2+ concentration ([Ca2+]i) in airway ciliary cells revealed that temperature (increasing from 25 to 37 °C) or 4αPDD (a selective transient receptor potential vanilloid 4 (TRPV4) agonist) stimulates a larger [Ca2+]i increase in Ts1Rhr than in Wt or Ts1Rhr:Pcp4+/+/-. In airway ciliary cells of Ts1Rhr, Pcp4-dose dependent activation of TRPV4 appears to induce an increase in the basal [Ca2+]i. In early embryonic day mice, a basal [Ca2+]i increased by PCP4 expressed may affect axonemal regulatory complexes regulated by the Ca2+-signal in Ts1Rhr, leading to a decrease in the basal CBF and CBA of airway cilia.

Keywords: Down syndrome mouse; PDE1; Pcp4; TRPV4; airway cilia; cAMP; intracellular Ca2+ concentration.

MeSH terms

  • Animals
  • Calcium / metabolism*
  • Calmodulin / metabolism
  • Cilia / metabolism*
  • Cyclic AMP / metabolism
  • Disease Models, Animal
  • Down Syndrome / metabolism*
  • Epithelial Cells / metabolism
  • Female
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Nerve Tissue Proteins / metabolism*
  • TRPV Cation Channels / metabolism
  • Trachea / metabolism

Substances

  • Calmodulin
  • Nerve Tissue Proteins
  • Pcp4 protein, mouse
  • TRPV Cation Channels
  • Cyclic AMP
  • Calcium