151
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Salzer I, Gafar H, Gindl V, Mahlknecht P, Drobny H, Boehm S. Excitation of rat sympathetic neurons via M1 muscarinic receptors independently of Kv7 channels. Pflugers Arch 2014; 466:2289-303. [PMID: 24668449 PMCID: PMC4233321 DOI: 10.1007/s00424-014-1487-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 02/13/2014] [Accepted: 02/14/2014] [Indexed: 01/14/2023]
Abstract
The slow cholinergic transmission in autonomic ganglia is known to be mediated by an inhibition of Kv7 channels via M1 muscarinic acetylcholine receptors. However, in the present experiments using primary cultures of rat superior cervical ganglion neurons, the extent of depolarisation caused by the M1 receptor agonist oxotremorine M did not correlate with the extent of Kv7 channel inhibition in the very same neuron. This observation triggered a search for additional mechanisms. As the activation of M1 receptors leads to a boost in protein kinase C (PKC) activity in sympathetic neurons, various PKC enzymes were inhibited by different means. Interference with classical PKC isoforms led to reductions in depolarisations and in noradrenaline release elicited by oxotremorine M, but left the Kv7 channel inhibition by the muscarinic agonist unchanged. M1 receptor-induced depolarisations were also altered when extra- or intracellular Cl− concentrations were changed, as were depolarising responses to γ-aminobutyric acid. Depolarisations and noradrenaline release triggered by oxotremorine M were reduced by the non-selective Cl− channel blockers 4-acetamido-4′-isothiocyanato-stilbene-2,2′-disulfonic acid and niflumic acid. Oxotremorine M induced slowly rising inward currents at negative membrane potentials that were blocked by inhibitors of Ca2+-activated Cl− and TMEM16A channels and attenuated by PKC inhibitors. These channel blockers also reduced oxotremorine M-evoked noradrenaline release. Together, these results reveal that slow cholinergic excitation of sympathetic neurons involves the activation of classical PKCs and of Ca2+-activated Cl− channels in addition to the well-known inhibition of Kv7 channels.
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Affiliation(s)
- Isabella Salzer
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringerstrasse 13a, 1090, Vienna, Austria
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152
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Bill A, Hall ML, Borawski J, Hodgson C, Jenkins J, Piechon P, Popa O, Rothwell C, Tranter P, Tria S, Wagner T, Whitehead L, Gaither LA. Small molecule-facilitated degradation of ANO1 protein: a new targeting approach for anticancer therapeutics. J Biol Chem 2014; 289:11029-11041. [PMID: 24599954 PMCID: PMC4036244 DOI: 10.1074/jbc.m114.549188] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
ANO1, a calcium-activated chloride channel, is highly expressed and amplified in human cancers and is a critical survival factor in these cancers. The ANO1 inhibitor CaCCinh-A01 decreases proliferation of ANO1-amplified cell lines; however, the mechanism of action remains elusive. We explored the mechanism behind the inhibitory effect of CaCCinh-A01 on cell proliferation using a combined experimental and in silico approach. We show that inhibition of ANO1 function is not sufficient to diminish proliferation of ANO1-dependent cancer cells. We report that CaCCinh-A01 reduces ANO1 protein levels by facilitating endoplasmic reticulum-associated, proteasomal turnover of ANO1. Washout of CaCCinh-A01 rescued ANO1 protein levels and resumed cell proliferation. Proliferation of newly derived CaCCinh-A01-resistant cell pools was not affected by CaCCinh-A01 as compared with the parental cells. Consistently, CaCCinh-A01 failed to reduce ANO1 protein levels in these cells, whereas ANO1 currents were still inhibited by CaCCinh-A01, indicating that CaCCinh-A01 inhibits cell proliferation by reducing ANO1 protein levels. Furthermore, we employed in silico methods to elucidate novel biological functions of ANO1 inhibitors. Specifically, we derived a pharmacophore model to describe inhibitors capable of promoting ANO1 degradation and report new inhibitors of ANO1-dependent cell proliferation. In summary, our data demonstrate that inhibition of the channel activity of ANO1 is not sufficient to inhibit ANO1-dependent cell proliferation, indicating that the role of ANO1 in cancer only partially depends on its function as a channel. Our results provide an impetus for gaining a deeper understanding of ANO1 modulation in cells and introduce a new targeting approach for antitumor therapy in ANO1-amplified cancers.
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Affiliation(s)
- Anke Bill
- Novartis Institutes for Biomedical Research, Cambridge, Massachusetts 02139
| | - Michelle Lynn Hall
- Novartis Institutes for Biomedical Research, Cambridge, Massachusetts 02139
| | - Jason Borawski
- Novartis Institutes for Biomedical Research, Cambridge, Massachusetts 02139
| | - Catherine Hodgson
- Novartis Institutes for Biomedical Research, Horsham, West Sussex, RH12 5AB, United Kingdom, and
| | - Jeremy Jenkins
- Novartis Institutes for Biomedical Research, Cambridge, Massachusetts 02139
| | - Philippe Piechon
- the Novartis Institutes for Biomedical Research, Basel CH-4002, Switzerland
| | - Oana Popa
- Novartis Institutes for Biomedical Research, Horsham, West Sussex, RH12 5AB, United Kingdom, and
| | | | - Pamela Tranter
- Novartis Institutes for Biomedical Research, Horsham, West Sussex, RH12 5AB, United Kingdom, and
| | - Scott Tria
- Novartis Institutes for Biomedical Research, Cambridge, Massachusetts 02139
| | - Trixie Wagner
- the Novartis Institutes for Biomedical Research, Basel CH-4002, Switzerland
| | - Lewis Whitehead
- Novartis Institutes for Biomedical Research, Cambridge, Massachusetts 02139
| | - L Alex Gaither
- Novartis Institutes for Biomedical Research, Cambridge, Massachusetts 02139,.
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153
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Jang Y, Oh U. Anoctamin 1 in secretory epithelia. Cell Calcium 2014; 55:355-61. [PMID: 24636668 DOI: 10.1016/j.ceca.2014.02.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2014] [Revised: 02/06/2014] [Accepted: 02/06/2014] [Indexed: 12/22/2022]
Abstract
Fluid and electrolyte releasing from secretory epithelia are elaborately regulated by orchestrated activity of ion channels. The activity of chloride channel at the apical membrane decides on the direction and the rate of secretory fluid and electrolyte. Chloride-dependent secretion is conventionally associated with intracellular increases in two second messengers, cAMP and Ca(2+), responding to luminal purinergic and basolateral adrenergic or cholinergic stimulation. While it is broadly regarded that cAMP-dependent Cl(-) secretion is regulated by cystic fibrosis transmembrane conductance regulator (CFTR), Ca(2+)-activated Cl(-) channel (CaCC) had been veiled for quite some time. Now, Anoctamin 1 (ANO1 or TMEM16A) confers Ca(2+)-activated Cl(-) currents. Ano 1 and its paralogs have been actively investigated for multiple functions underlying Ca(2+)-activated Cl(-) efflux and fluid secretion in a variety of secretory epithelial cells. In this review, we will discuss recent advances in the secretory function and signaling of ANO1 in the secretory epithelia, such as airways, intestines, and salivary glands.
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Affiliation(s)
- Yongwoo Jang
- Sensory Research Center, Creative Research Initiatives, College of Pharmacy, Seoul National University, Seoul, Republic of Korea
| | - Uhtaek Oh
- Sensory Research Center, Creative Research Initiatives, College of Pharmacy, Seoul National University, Seoul, Republic of Korea; Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Science and Technology, Seoul National University, Republic of Korea.
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