Why muscles weaken and immunity fails: Investigating the role of calmodulin

About the Project

This PhD project investigates how calmodulin regulates calcium channels Orai1 and STIM1, and how mutations can cause muscle weakness and immune failure. Using biochemistry, cell physiology and structural biology, we will map calmodulin interactions, reveal disease mechanisms and identify potential therapeutic targets. Data obtained will advance our understanding of calcium signalling, with broad biomedical implications.

Background.

Calcium signals are essential for processes such as muscle contraction, immune activation, and brain function. They are controlled by calcium channels that regulate calcium entry into cells. Mutations in these channels cause channelopathies, leading to diverse diseases. Recently, severe mutations in Orai1 and STIM1 have been linked to muscular hypotonia and immunodeficiency. Many occur where these channels interact with calmodulin, a universal calcium sensor. Although calmodulin is crucial for calcium regulation, its role in Orai1 and STIM1 control remains poorly understood, leaving a major knowledge gap. This project will investigate how calmodulin interacts with these channels, and how mutations disrupt this regulation, leading to disease. By linking molecular defects to muscle and immune dysfunction, we aim to uncover the mechanisms behind these conditions. Insights gained could not only explain rare disorders but also guide therapeutic strategies and advance understanding of calcium signalling in health and disease.

Hypothesis and aims.

We hypothesise that mutations in Orai1 and STIM1 disrupt normal calmodulin regulation of calcium channels, leading to abnormal signalling that underlies muscular hypotonia and immunodeficiency.The specific aims of the project are to:

1. Characterise calmodulin binding to Orai1 and STIM1, in both healthy and disease-associated forms.
2. Determine how calmodulin regulates calcium channel activity in living cells.
3. Resolve structural features of calmodulin-channel complexes, identifying conformational changes caused by mutations.
4. Link molecular changes to cellular consequences, showing how defective signalling contributes to muscle and immune dysfunction.

Research plan.

This PhD will combine biochemistry, structural biology, cell physiology, and electrophysiology to develop a detailed understanding of calmodulin regulation in channelopathies.

• Molecular biology and protein biochemistry: Mutant and wild-type versions of Orai1 and STIM1 will be engineered. Protein binding assays will be used to quantitatively map calmodulin interaction sites.
• Functional studies: Live-cell calcium imaging and patch-clamp electrophysiology will reveal how calmodulin influences channel behaviour in real time.
• Structural biology: X-ray crystallography will be applied to visualise calmodulin-channel complexes at high resolution.
• Cell-based studies: We will link molecular defects to physiological outcomes using muscle and immune cells.

By integrating these approaches, the student will generate both mechanistic insights and disease-relevant connections.

Outcomes.

This project will define how calmodulin regulates Orai1 and STIM1, showing how mutations disrupt calcium signalling and cause hypotonia and immunodeficiency. By linking molecular defects to cellular effects, it will close a key knowledge gap in calcium channelopathies and highlight therapeutic targets. Insights will also advance understanding of calcium signalling in cardiovascular, nervous and immune systems.

Training and development opportunities.

This PhD project offers exceptional training across disciplines, providing the successful candidate with a highly versatile skill set.

• Molecular cloning, mutagenesis, and protein engineering.
• Protein purification and binding studies.
• Advanced microscopy (confocal and super-resolution imaging).
• Electrophysiology (patch-clamp techniques).
• Structural biology approaches for protein complexes.
• Cell culture and live-cell functional assays.
• Transferable skills (critical thinking, experimental design, data analysis, scientific writing, and oral presentation).