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Biochim Biophys Acta Mol Cell Biol Lipids. 2018 Mar;1863(3):299-312. doi: 10.1016/j.bbalip.2017.12.009. Epub 2017 Dec 22.

Phosphatidylinositol 4,5-bisphosphate, cholesterol, and fatty acids modulate the calcium-activated chloride channel TMEM16A (ANO1).

Author information

1
Physics Institute, Universidad Autónoma de San Luis Potosí, Ave. Dr. Manuel Nava #6, San Luis Potosí, SLP 78290, Mexico.
2
Laboratorio de Neurobiología Molecular y Celular, Instituto de Neurobiología Universidad Nacional Autónoma de México, Boulevard Juriquilla 3001, Querétaro 76230, Mexico.
3
Center for Medical Research, Affiliated Hospital, Qingdao University, Shangdong 266071, PR China.
4
Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA.
5
Department of Physiology and Biophysics, Universidad Autónoma de San Luis Potosí School of Medicine, Ave. V. Carranza 2405, San Luis Potosí, SLP 78290, Mexico.
6
Physics Institute, Universidad Autónoma de San Luis Potosí, Ave. Dr. Manuel Nava #6, San Luis Potosí, SLP 78290, Mexico. Electronic address: arreola@dec1.ifisica.uaslp.mx.

Abstract

The TMEM16A-mediated Ca2+-activated Cl- current drives several important physiological functions. Membrane lipids regulate ion channels and transporters but their influence on members of the TMEM16 family is poorly understood. Here we have studied the regulation of TMEM16A by phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2), cholesterol, and fatty acids using patch clamp, biochemistry and fluorescence microscopy. We found that depletion of membrane PI(4,5)P2 causes a decline in TMEM16A current that is independent of cytoskeleton, but is partially prevented by removing intracellular Ca2+. On the other hand, supplying PI(4,5)P2 to inside-out patches attenuated channel rundown and/or partially rescued activity after channel rundown. Also, depletion (with methyl-β-cyclodextrin M-βCD) or restoration (with M-βCD+cholesterol) of membrane cholesterol slows down the current decay observed after reduction of PI(4,5)P2. Neither depletion nor restoration of cholesterol change PI(4,5)P2 content. However, M-βCD alone transiently increases TMEM16A activity and dampens rundown whereas M-βCD+cholesterol increases channel rundown. Thus, PI(4,5)P2 is required for TMEM16A function while cholesterol directly and indirectly via a PI(4,5)P2-independent mechanism regulate channel function. Stearic, arachidonic, oleic, docosahexaenoic, and eicosapentaenoic fatty acids as well as methyl stearate inhibit TMEM16A in a dose- and voltage-dependent manner. Phosphatidylserine, a phospholipid whose hydrocarbon tails contain stearic and oleic acids also inhibits TMEM16A. Finally, we show that TMEM16A remains in the plasma membrane after treatment with M-βCD, M-βCD+cholesterol, oleic, or docosahexaenoic acids. Thus, we propose that lipids and fatty acids regulate TMEM16A channels through a membrane-delimited protein-lipid interaction.

KEYWORDS:

Anoctamin; Fluorescence microscopy; Lipids; Patch clamp; Poly-unsaturated fatty acids; Regulation; TMEM16A

PMID:
29277655
PMCID:
PMC5807209
[Available on 2019-03-01]
DOI:
10.1016/j.bbalip.2017.12.009
[Indexed for MEDLINE]

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