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Updated: Jul 3, 2026
In vitro Measurements of Tracheal Constriction Using Mice
Published on: June 25, 2012
Bestrophin 1 and 2 are components of the Ca(2+) activated Cl(-) conductance in mouse airways
René Barro-Soria1, Rainer Schreiber, Karl Kunzelmann
1Institut für Physiologie, Universität Regensburg, Universitätsstrasse 31, D-93053 Regensburg, Germany.
Abstract:
Ca(2+) activated Cl(-) transport is found in airways and other organs and is abnormal in cystic fibrosis, polycystic kidney disease and infectious diarrhea. The molecular identity of Ca(2+) activated Cl(-) channels (CaCC) in the airways is still obscure. Bestrophin proteins were described to form CaCC and to regulate voltage gated Ca(2+) channels. The present Ussing chamber recordings on tracheas of bestrophin 1 knockout (vmd2(-/-)) mice indicate a reduced Cl(-) secretion when activated by the purinergic agonist ATP (0.1-1 muM). As two paralogs, best1 and best2, are present in mouse tracheal epithelium, we examined the contribution of each paralog to Ca(2+) activated Cl(-) secretion. In whole cell patch-clamp measurements on primary airway epithelial cells from vmd2(-/-) tracheas, ATP activated Cl(-) currents were reduced by 50%. Additional knockdown of mbest2 in vmd2(-/-) cells by short interfering RNA further suppressed ATP-induced Cl(-) currents down to 20% of that observed in cells from vmd2(+/+) animals. Moreover, RNAi-suppression of both mbest1 and mbest2 reduced CaCC in vmd2(+/+) cells. Direct activation of CaCC by increase of intracellular Ca(2+) was also reduced in whole cell recordings of vmd2(-/-) cells. These results clearly suggest a role of bestrophin 1 and 2 for Ca(2+) dependent Cl(-) secretion in mouse airways.
Insights
Bestrophin 1 and 2 play a role in calcium-activated chloride channel (CaCC) function in mouse airways. These proteins are crucial for proper chloride secretion, which is impaired in diseases like cystic fibrosis.
Area of Science:
- Physiology
- Molecular Biology
- Ion Transport
Background:
- Calcium-activated chloride channels (CaCC) are vital for airway function but their molecular identity remains unclear.
- Dysfunctional CaCC is implicated in diseases such as cystic fibrosis and polycystic kidney disease.
- Bestrophin proteins are known to form CaCC and modulate calcium channels.
Purpose of the Study:
- To investigate the role of bestrophin 1 and bestrophin 2 in calcium-activated chloride secretion in mouse airways.
- To elucidate the specific contribution of bestrophin paralogs to CaCC activity in the tracheal epithelium.
Main Methods:
- Ussing chamber recordings on tracheas from bestrophin 1 knockout mice.
- Whole-cell patch-clamp measurements on primary airway epithelial cells.
- Short interfering RNA (siRNA) mediated knockdown of bestrophin 2 in knockout cells.
- RNA interference (RNAi) to suppress both bestrophin 1 and 2.
Main Results:
- Bestrophin 1 knockout mice exhibited reduced chloride secretion upon ATP stimulation.
- Knockdown of bestrophin 2 in bestrophin 1 knockout cells further decreased ATP-induced chloride currents.
- RNAi suppression of both bestrophins significantly reduced CaCC activity.
- Direct calcium activation of CaCC was also diminished in bestrophin 1 knockout cells.
Conclusions:
- Bestrophin 1 and bestrophin 2 are essential for calcium-dependent chloride secretion in mouse airways.
- These findings identify bestrophins as key players in airway ion transport and potential therapeutic targets.
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