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TMEM16B is a Dominant Component of the Cholecystokinin–Activated Cl ‐ Conductance in Vagal Afferents that is Down‐Regulated in Mice on High Fat Diet
Author(s) -
Wang Runping,
Lu Yongjun,
Cicha Michael,
Chapleau Mark,
Benson Christopher,
Abboud Francois
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.818.4
Subject(s) - cholecystokinin , chemistry , conductance , endocrinology , medicine , neuroscience , biology , receptor , biochemistry , physics , condensed matter physics
We have reported cholecystokinin (CCK) sensitive Ca 2+ ‐activated chloride (Cl ‐ ) currents (CaCCs) in DiI labeled intestinal nodose ganglia neurons from C57BL/6 mice. These CaCCs were significantly reduced from 24.8±4.9 (n=7) to 6.1±2.9 pA/pF, (n=7, p<0.01) with mice fed a 60% high fat diet (HFD) for 10 weeks. Here we characterize the effect of CCK on the anoctamins (Ano1 and 2/TMEM16A and B) that function as Ca 2+ ‐activated Cl ‐ conductance. They are expressed in nodose ganglia, downregulated by HFD, and hence may regulate satiety signaling. We found that the CCK‐induced Cl ‐ current was only inhibited by a high dose of niflumic acid (NFA) (300 uM) which inhibits both TMEM 16A and 16B currents (26.9±4.7 pA/pF before vs. 10.3±2.1 pA/pF after NFA, n=10, p<0.01). However, the specific TMEM16A inhibitor T16Ainh‐A01 (30 uM) did not reduce the current (30.4±6.1 pA/pF before vs. 26.9±5.2 pA/pF after, n=8, p>0.1). The excised inside‐out patch recording showed that a very high [Ca 2+ ] i (>1 uM) was required to activate the Cl ‐ current, which is more consistent with the response of the TMEM16B subunit rather than TMEM16A which is much more sensitive to [Ca 2+ ] i . Transfection of lentivirus carrying shRNA targeting TMEM16B reduced the CCK‐current to 22.03±3.7 (n=8) from the value of 35.1±3.4 pA/pF (n=6, p<0.05) obtained with scrambled shRNA. Co‐transfection of shRNA targeting both TMEM16A and 16B did not result in further reduction of the CCK‐induced current (20.0±4.2 pA/pF, n=6). We conclude that TMEM16B is a dominant component of the CCK‐induced Ca 2+ ‐activated Cl ‐ conductance. A dysfunctional TMEM16B may impair satiety in HFD obesity.