The role and regulation of TMEM16A in the vascular system
TMEM16A is a Ca2+-activated Cl- channel (CaCC) encoded by the TMEM16A gene, expressed in vascular smooth muscle cells (VSMCs). TMEM16A has a proposed role in depolarising the membrane potential (Vm) in response to activation of the Gq-protein coupled receptor (Gq-PCR) signalling cascade. Therefore,...
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| Formato: | Thesis |
| Idioma: | English |
| Publicado em: |
2019
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| _version_ | 1826309230356856832 |
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| author | Acheson, K |
| author2 | Tammaro, P |
| author_facet | Tammaro, P Acheson, K |
| author_sort | Acheson, K |
| collection | OXFORD |
| description | TMEM16A is a Ca2+-activated Cl- channel (CaCC) encoded by the TMEM16A gene, expressed in vascular smooth muscle cells (VSMCs). TMEM16A has a proposed role in depolarising the membrane potential (Vm) in response to activation of the Gq-protein coupled receptor (Gq-PCR) signalling cascade. Therefore, TMEM16A may constitute a key contractile mechanism in VSMCs. Recent elucidation of the TMEM16A channel structure has revealed that the pore region is partially exposed to the plasma membrane. It is therefore hypothesised that TMEM16A may be sensitive to the lipid composition of the plasma membrane. This thesis explores the lipid regulation of cloned TMEM16A channels, and the role of lipids in the control of native TMEM16A currents in VSMCs, and the importance of this in murine arterial (aortic) tone.
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The main findings of this thesis are:
1, The TMEM16A pharmacological modulator 2-(4-chloro-2-methylphenoxy)-N-[(2- methoxyphenyl)methylideneamino]-acetamide (Ani9) is currently the most potent and efficacious modulator of TMEM16A available. This study demonstrated that Ani9 was selective for TMEM16A in VSMCs. Studies involving Ani9 and a heterozygous knock-out of TMEM16A were used to confirm that TMEM16A is functionally expressed in VSMCs, and that TMEM16A has a key role in vascular contraction.
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2, Plasma membrane levels of the intracellular signalling lipid phosphatidylinositol 4,5- bisphosphate (PIP2) are dynamically controlled during activation of Gq-PCR. Whether these changes affect TMEM16A was unknown. Here, it was found that PIP2 increased TMEM16A channel activity. This effect was especially pronounced at physiologically relevant intracellular Ca2+ concentrations ([Ca2+]i) and membrane potentials (Vm). This revealed a novel pathway in the Gq-PCR signalling cascade.
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3, The dietary polyunsaturated fatty acid (PUFA) docosahexaenoic acid (DHA) was found to inhibit cloned and native TMEM16A channels. Consistent with this observation, DHA reduced agonist-induced contraction of isolated aortic rings. This observation provided a mechanistic basis for the reported vasodilator properties of DHA.
To conclude, the research in this thesis has demonstrated that TMEM16A is highly sensitive to both intracellular lipids (PIP2) and extracellular lipids (DHA). This could form the basis for future studies investigating the TMEM16A pore region, in order to explore whether the TMEM16A pore region could be exploited as a target for pharmacological intervention. |
| first_indexed | 2024-03-07T07:31:02Z |
| format | Thesis |
| id | oxford-uuid:d98aa016-1c6f-4140-b8f3-8315de54643f |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T07:31:02Z |
| publishDate | 2019 |
| record_format | dspace |
| spelling | oxford-uuid:d98aa016-1c6f-4140-b8f3-8315de54643f2023-01-10T22:11:21ZThe role and regulation of TMEM16A in the vascular systemThesishttp://purl.org/coar/resource_type/c_db06uuid:d98aa016-1c6f-4140-b8f3-8315de54643fEnglishHyrax Deposit2019Acheson, KTammaro, PTMEM16A is a Ca2+-activated Cl- channel (CaCC) encoded by the TMEM16A gene, expressed in vascular smooth muscle cells (VSMCs). TMEM16A has a proposed role in depolarising the membrane potential (Vm) in response to activation of the Gq-protein coupled receptor (Gq-PCR) signalling cascade. Therefore, TMEM16A may constitute a key contractile mechanism in VSMCs. Recent elucidation of the TMEM16A channel structure has revealed that the pore region is partially exposed to the plasma membrane. It is therefore hypothesised that TMEM16A may be sensitive to the lipid composition of the plasma membrane. This thesis explores the lipid regulation of cloned TMEM16A channels, and the role of lipids in the control of native TMEM16A currents in VSMCs, and the importance of this in murine arterial (aortic) tone. <br></br> The main findings of this thesis are: 1, The TMEM16A pharmacological modulator 2-(4-chloro-2-methylphenoxy)-N-[(2- methoxyphenyl)methylideneamino]-acetamide (Ani9) is currently the most potent and efficacious modulator of TMEM16A available. This study demonstrated that Ani9 was selective for TMEM16A in VSMCs. Studies involving Ani9 and a heterozygous knock-out of TMEM16A were used to confirm that TMEM16A is functionally expressed in VSMCs, and that TMEM16A has a key role in vascular contraction. <br></br> 2, Plasma membrane levels of the intracellular signalling lipid phosphatidylinositol 4,5- bisphosphate (PIP2) are dynamically controlled during activation of Gq-PCR. Whether these changes affect TMEM16A was unknown. Here, it was found that PIP2 increased TMEM16A channel activity. This effect was especially pronounced at physiologically relevant intracellular Ca2+ concentrations ([Ca2+]i) and membrane potentials (Vm). This revealed a novel pathway in the Gq-PCR signalling cascade. <br></br> 3, The dietary polyunsaturated fatty acid (PUFA) docosahexaenoic acid (DHA) was found to inhibit cloned and native TMEM16A channels. Consistent with this observation, DHA reduced agonist-induced contraction of isolated aortic rings. This observation provided a mechanistic basis for the reported vasodilator properties of DHA. To conclude, the research in this thesis has demonstrated that TMEM16A is highly sensitive to both intracellular lipids (PIP2) and extracellular lipids (DHA). This could form the basis for future studies investigating the TMEM16A pore region, in order to explore whether the TMEM16A pore region could be exploited as a target for pharmacological intervention. |
| spellingShingle | Acheson, K The role and regulation of TMEM16A in the vascular system |
| title | The role and regulation of TMEM16A in the vascular system |
| title_full | The role and regulation of TMEM16A in the vascular system |
| title_fullStr | The role and regulation of TMEM16A in the vascular system |
| title_full_unstemmed | The role and regulation of TMEM16A in the vascular system |
| title_short | The role and regulation of TMEM16A in the vascular system |
| title_sort | role and regulation of tmem16a in the vascular system |
| work_keys_str_mv | AT achesonk theroleandregulationoftmem16ainthevascularsystem AT achesonk roleandregulationoftmem16ainthevascularsystem |