From molecular defects to cardiac dysfunction: Troponin I mutations in hypertrophic cardiomyopathy

About the Project

Background. Hypertrophic cardiomyopathy (HCM) is the most common inherited heart disease, affecting 1 in 500 people. HCM thickens the heart muscle, impairing relaxation and pumping, and increases risks of arrhythmia and sudden death. Symptoms range from mild to severe heart failure. HCM usually arises from mutations in sarcomeric proteins that drive contraction. Cardiac troponin I (cTnI) is central to this process, acting as a calcium-sensitive switch that controls contraction. Mutations in cTnI can disrupt this regulation, often causing severe, early-onset HCM with high complication risk. However, the precise mechanisms by which mutations alter contraction remain poorly understood. This knowledge gap hinders prediction of disease severity and development of targeted therapies. A deeper understanding of how cTnI mutations affect sarcomere regulation at the molecular level is critical. Such insights could reveal the mechanisms of dysfunction and guide novel strategies to restore normal heart muscle function.

Hypothesis and aims. We hypothesise that cTnI mutations alter the structure and function of the troponin complex, leading to abnormal calcium sensitivity, sarcomere dysfunction, and the cellular features underlying HCM.The project aims to:

1. Characterise TnI interactions within the troponin complex.
2. Determine structural consequences of TnI mutations using X-ray crystallography and cryo-electron microscopy (cryo-EM).
3. Assess functional effects on thin filament regulation.

By integrating interaction studies, high-resolution structural analysis, and functional assays, this project will establish a mechanistic framework connecting TnI mutations to sarcomere dysfunction and HCM pathology.

Research plan. This interdisciplinary project combines protein biochemistry, structural biology, and functional assays to investigate how troponin I (TnI) mutations contribute to hypertrophic cardiomyopathy (HCM).

• Troponin Complex Interactions: TnI proteins will be recombinantly expressed and purified. Their interactions with troponin T and troponin C will be quantified using biophysical approaches, identifying how mutations alter complex formation and stability.
• Structural Studies: Structural consequences of TnI mutations will be explored using X-ray crystallography and cryo-EM. These techniques will resolve high-resolution conformational changes in troponin complexes, revealing the molecular basis of disrupted regulation.
• Functional Assays: The effects of TnI mutations on thin filament regulation will be examined using biochemical assays and confocal microscopy.

Outcome. This project will define how TnI mutations disrupt troponin complex structure and function, linking molecular changes to altered calcium handling, sarcomere organisation and cardiomyocyte contraction. Integrating cryo-EM with confocal microscopy will establish clear genotype-to-phenotype relationships, providing mechanistic insight into HCM. Findings will advance understanding of the disease pathology and inform potential therapeutic strategies targeting sarcomere dysfunction.

Training and development opportunities. The successful candidate will gain comprehensive, hands-on experience in cutting-edge techniques, including:

• Molecular biology and protein biochemistry: recombinant protein expression/purification and functional characterisation.
• Structural biology: X-ray crystallography and cryo-EM, data collection, and 3D reconstruction.
• Functional Assays: ATPase activity and in vitro motility assays.
• Cellular Imaging: Confocal microscopy in cardiomyocytes.

Data analysis and scientific communication: interpreting complex datasets, preparing publications, and presenting at national/international conferences.

For informal enquiries, please contact:

Dr Nordine Helassa – nhelassa@liverpool.ac.uk

To apply, please send your CV and a short statement of interest to Dr Helassa.