LICAMM Ion channel regulation in cardiovascular disease

Summary

Ion channels are key regulators of blood vessel function and health. A diverse variety of ion channels are expressed in endothelial cells and regulate many physiological regulatory processes, such as the cell membrane potential, signal transduction, hemodynamics, and vasomotor functions. Changes in these ion channel activities may be involved in the pathological state of the vascular system, via influencing endothelial dysfunction, leading to atherosclerosis. Despite their importance, the regulation of ion channels in endothelial cells has been poorly studied.

The Alzheimer’s disease related protein, BACE1, has been shown to regulate ion channel function, specifically voltage gated sodium channel and KCNQ potassium channels, in neurons. Mechanistically BACE1 is capable of regulating ion channel function via two processes (1) cleavage of accessory channel subunits and (2) through direct, non-enzymatic interactions with main channel subunits. The different forms of interaction with BACE1 influence channel function and are thus expected to have an impact on cellular function. While BACE1 has been extensively researched in neuronal cells, the role of BACE1-mediated ion channel function in endothelial cells is yet to be explored.

Furthermore, BACE1 expression and activity is known be enhanced in type 2 diabetes. This alludes to an interesting concept that BACE1 drives endothelial dysfunction by altering ion channel activity. As such reducing BACE1 levels and/or activity may be a novel therapeutic target for cardiovascular disease.

Aim

The aim of this project is to explore the mechanisms of BACE1 mediated regulation of ion channel activity in endothelial cells. To achieve this the fellow will use a combination of electrophysiology and molecular biology techniques, alongside functional assays to examine the role of BACE1 in channel function.

Project

Super resolution imaging, biochemical, and functional analyses will be used to test the hypothesis that BACE-1 controls endothelial cells physiology via regulating ion channel activity.

Channels including TRPV4, ORAI1, PIEZO1, KATP and EnNaC are important regulators of endothelial function. We have expertise in investigating activity of these ion channels in response to physiological and pathological stimuli, such as shear stress. Thus the fellow will use targeted gene deletion, inhibitors and over-expression systems in combination with patch-clamping techniques, to examine the specific role(s) of BACE-1 in regulation of ion channel activity in endothelial cells. The effect of BACE1 expression and activity on numbers of channels per cell, channel conductance, or open probability will be calculated. In addition, downstream signalling and calcium influx will be measured using western blotting and fluorescent imaging, respectively.

Once established the fellow will further explore this relationship in the setting of endothelial dysfunction and vascular disease using cardiovascular disease patient derived cells.

Thus this study seeks to establish a hitherto unknown function for BACE1 in endothelial physiology and explore the possibility of repurposing of BACE1 inhibitors as agents for controlling ion channel-driven vascular disease processes.

References

Lehnert S, Hartmann S, Hessler S, Adelsberger H, Huth T, Alzheimer C. Ion channel regulation by β-secretase BACE1 - enzymatic and non-enzymatic effects beyond Alzheimer's disease. Channels (Austin). 2016;10(5):365-378. doi:10.1080/19336950.2016.1196307

Meakin, P. J., Coull, B. M., Tuharska, Z., McCaffery, C., Akoumianakis, I., Antoniades, C., Brown, J., Griffin, K. J., Platt, F., Ozber, C. H., Yuldasheva, N. Y., Makava, N., Skromna, A., Prescott, A., McNeilly, A. D., Siddiqui, M., Palmer, C. N., Khan, F., & Ashford, M. L. (2020). Elevated circulating amyloid concentrations in obesity and diabetes promote vascular dysfunction. The Journal of clinical investigation, 130(8), 4104–4117. doi.org/10.1172/JCI122237

Santos-Gomes J, Le Ribeuz H, Brás-Silva C, Antigny F, Adão R. Role of Ion Channel Remodeling in Endothelial Dysfunction Induced by Pulmonary Arterial Hypertension. Biomolecules. 2022 Mar 22;12(4):484. doi: 10.3390/biom12040484.

Shi J, Hyman AJ, De Vecchis D, Chong J, Lichtenstein L, Futers TS, Rouahi M, Salvayre AN, Auge N, Kalli AC, Beech DJ. Sphingomyelinase Disables Inactivation in Endogenous PIEZO1 Channels. Cell Rep. 2020 Oct 6;33(1):108225. doi: 10.1016/j.celrep.2020.108225.

A degree in biological sciences, dentistry, medicine, midwifery, nursing, psychology or a good honours degree in a subject relevant to the research topic. A Masters degree in a relevant subject is desirable, but not essential.

Applicants whose first language is not English must provide evidence that their English language is sufficient to meet the specific demands of their study. The minimum requirements for this programme in IELTS and TOEFL tests are: • British Council IELTS - score of 7.0 overall, with no element less than 6.5 • TOEFL iBT - overall score of 100 with the listening and reading element no less than 22, writing element no less than 23 and the speaking element no less than 24.