TMEM16B determines cholecystokinin sensitivity of intestinal vagal afferents of nodose neurons
Runping Wang, … , Mark W. Chapleau, François M. Abboud
Runping Wang, … , Mark W. Chapleau, François M. Abboud
Published March 7, 2019
Citation Information: JCI Insight. 2019;4(5):e122058. https://doi.org/10.1172/jci.insight.122058.
View: Text | PDF
Research Article Cell biology Metabolism

TMEM16B determines cholecystokinin sensitivity of intestinal vagal afferents of nodose neurons

Abstract

The satiety effects and metabolic actions of cholecystokinin (CCK) have been recognized as potential therapeutic targets in obesity for decades. We identified a potentially novel Ca2+-activated chloride (Cl–) current (CaCC) that is induced by CCK in intestinal vagal afferents of nodose neurons. The CaCC subunit Anoctamin 2 (Ano2/TMEM16B) is the dominant contributor to this current. Its expression is reduced, as is CCK current activity in obese mice on a high-fat diet (HFD). Reduced expression of TMEM16B in the heterozygote KO of the channel in sensory neurons results in an obese phenotype with a loss of CCK sensitivity in intestinal nodose neurons, a loss of CCK-induced satiety, and metabolic changes, including decreased energy expenditure. The effect on energy expenditure is further supported by evidence in rats showing that CCK enhances sympathetic nerve activity and thermogenesis in brown adipose tissue, and these effects are abrogated by a HFD and vagotomy. Our findings reveal that Ano2/TMEM16B is a Ca2+-activated chloride channel in vagal afferents of nodose neurons and a major determinant of CCK-induced satiety, body weight control, and energy expenditure, making it a potential therapeutic target in obesity.

Authors

Runping Wang, Yongjun Lu, Michael Z. Cicha, Madhu V. Singh, Christopher J. Benson, Christopher J. Madden, Mark W. Chapleau, François M. Abboud

×

Figure 3

HFD suppresses CCK-8 responses and Ano1 and Ano2 expression in intestinal nodose neurons.

Options: View larger image (or click on image) Download as PowerPoint
HFD suppresses CCK-8 responses and Ano1 and Ano2 expression in intestina...
(A) The body weight of the C57BL/6 mice (n = 24) fed HFD was much greater (41.4 ± 0.9 g, at 20.6 ± 0.4 weeks) than control mice (n = 24) fed regular chow (28.4 ± 0.7 g, at 21.0 ± 0.5weeks, **P < 0.001). (B) The relative mRNA level of CCK1 receptor (CCKR[A]) in nodose ganglia from mice fed HFD is 1.54 ± 0.41-fold the level from the control group fed regular chow (1.06 ± 0.37, *P < 0.05). The level of CCK2 receptor (CCKR[B]) mRNA shows no significant difference between these 2 groups (P > 0.05; n = 6 ganglia from 3 mice in each group). (C) The mRNA level of Ano1 is reduced from 1.01 ± 0.20 to 0.61 ± 0.09 fold (**P < 0.001), and the Ano2 level is decreased from 1.02 ± 0.22 (n = 6) to 0.31 ± 0.07-fold (**P < 0.01) in ganglia from mice fed regular chow vs. HFD (n = 6 ganglia from 3 mice in each group). (D) The protein expression of both TMEM16A (green) and TMEM16B (red) are reduced in nodose ganglia from mice fed HFD compared with regular chow. (E) Quantitation showed the fluorescence intensity in mice fed control vs. HFD diet is 99.8 ± 13.8 vs. 41.4 ± 6.4 for TMEM16A and 51.9 ± 9.0 vs. 23.7 ± 4.7 AU for TMEM16B (n = 3–4 slices from 6 ganglia of 3 mice in each group, *P < 0.05 and **P < 0.01). (F) CCK-8–induced increases in [Ca2+]i are not different in labeled intestinal nodose neurons from mice fed HFD or regular chow (n = 3–5 neurons from 4 ganglia of 2 mice, P > 0.05). (G) The CCK-8–induced Ca2+-activated Cl– current (CaCC) in DiI-labeled nodose neurons innervating proximal intestine is attenuated from 32.0 ± 8.7 to 12.4 ± 3.3 pA/pF in mice fed regular chow vs. HFD, respectively (n = 7 and 10 neurons from 4 ganglia of 2 mice, *P < 0.05). The osmolarity induced volume-regulated anion channel (VRAC) (SWELL/LRRC8) currents, which are inhibited by DCPIB; however, they show no difference between 2 groups (44.0 ± 3.9 vs. 47.7 ± 8.5 pA/pF in labeled nodose neurons from 8 ganglia of 4 mice fed regular chow vs. 4 ganglia of 2 mice fed HFD, respectively, P > 0.05). Each data point represents 1 individual nodose neuron. Data are presented as means ± SEM, unpaired 2-tailed Student’s t test.