4-year PhD Studentship: Biochemical changes in coronary microvascular endothelial glycocalyx in diabetic cardiomyopathy and therapeutic potential of restoring glycocalyx components at University of Bristol on FindAPhD.com

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Dr Yan Qiu, Dr S Satchell, Prof P Madeddu, Prof Jerry Turnbull No more applications being accepted Self-Funded PhD Students Only

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Bristol United Kingdom Biological Sciences

About the Project

The endothelial glycocalyx (eGlx) is present on all endothelial cells and composed largely of proteoglycans. Proteoglycans consist of core proteins and glycosaminoglycan (GAG) side chains, of which heparan sulphate is predominant.

EGlx has vital roles in vascular function including in the regulation of microvascular permeability. Tight regulation of coronary microvascular permeability is necessary to maintain normal heart function. Increased permeability and consequent oedema impair contractility leading to heart failure.

We have shown eGlx damage in diabetic cardiomyopathy (DCM) in mouse models. Glycocalyx damage is associated with increased permeability of coronary microvascular endothelial cells (CMVEC) and is sufficient to impair heart function. Angiopoietin 1 (Ang1) treatment restores glycocalyx and improves diastolic function.

The properties of proteoglycans depend on the fine chemical structure of component GAG. Therefore, defining GAG structure and its change in heart diseases is a key step in establishing the structure-activity relationship required for understanding the contribution of eGlx to heart diseases. However, the changes in the eGlx component GAG and its structure in DCM have not been looked at.

Taken together, this suggests the biochemical changes in eGlx GAG maybe important in DCM, and correction of GAG structure and restoration of glycocalyx maybe a therapeutic target in DCM.

Aims and objectives

Determine the eGlx-related gene expression in the coronary microvascular endothelial cells in DCM.
Define the biochemical changes in GAG in the coronary microvascular endothelial glycocalyx in DCM, focusing on eGlx heparan sulphate.
Modulate expression of enzymes responsible for heparan sulphate synthesis/shedding to ameliorate eGlx damage and dysfunction of human CMVEC cultured in diabetic milieu.
Identify the mechanisms of Ang1 restoring eGlx and alleviating dysfunction of CMVEC cultured in diabetic milieu.

Outcomes: students working in a large, friendly group with excellent peer support and training record. It is expected student work will contribute to high impact publications.

Methodology

Aim 1:

Induce diabetes in FVB mice with streptozotocin injections.
Monitor heart function by echocardiography for 9 weeks to confirm the development of DCM.
Collect heart endothelial cells by fluorescent activated cell sorting. Examine changes in eGlx-related gene expression in diabetic heart by RNA sequencing.

Aim 2:

Induce DCM as in Aim 1.
Determine change in composition of eGlx enzymatically eluted from diabetic hearts by GAG analysis and more detailed disaccharide analysis (This part of the work will be in collaboration with Prof. Jerry Turnbull at the University of Liverpool).

Aim 3:

Perform overexpression/knockdown of genes identified through the analyses in aim 2 in CMVEC by techniques of lentiviral vectors and shRNA.
Examine effects of gene manipulations on the eGlx composition of CMVEC cultured in diabetic milieu with techniques as in Aim 2, and on CMVEC permeability with transendothelial protein passage assay.

Aim 4:

Determine effects of Ang1 on the genes identified through the analyses in aim 2 in CMVEC cultured in diabetic milieu by RT-qPCR, Western blotting, and immunofluorescence.
Examine effects of Ang1 on CMVEC eGlx composition as in Aim 2, and on CMVEC permeability as in Aim 3.

How to apply for this project

This project will be based in Bristol Medical School - Translational Health Sciences in the Faculty of Health Sciences at the University of Bristol.

Please visit the Faculty of Health Sciences website for details of how to apply

Funding Notes

This project is open for University of Bristol PGR scholarship applications (closing date 25th February 2022)
The University of Bristol PGR scholarship pays tuition fees and a maintenance stipend (at the minimum UKRI rate) for the duration of a PhD (typically three years but can be up to four years).

References

1. Y Qiu, et al, S C Satchell. Endothelial glycocalyx is damaged in diabetic cardiomyopathy: angiopoietin 1 restores glycocalyx and improves diastolic function. Diabetologia. 2021 (In press)
2. Murtaza G, et al. (2019) Diabetic cardiomyopathy - A comprehensive updated review. Progress in cardiovascular diseases 62(4): 315-326.
3. Becker BF, et al. (2010) Therapeutic strategies targeting the endothelial glycocalyx: acute deficits, but great potential. Cardiovasc Res 87(2): 300-310.
4. Turnbull JE (2018) Enhancing the glycosciences toolkit: new GAGs in the lineup. Nature methods 15(11): 867-868.