Dr Samantha Pitt
Royal Society of Edinburgh Biomedical Fellow
Tel: 01334 463156
In healthy individuals, the controlled release of calcium causes the heart to beat strongly. In heart failure and fatal arrhythmias the release of calcium becomes erratic leading to weakened contraction of heart muscle and cell death. Using a combination of low noise electrophysiological recordings in combination with molecular and biochemical methods, my group investigates intracellular calcium dynamics and the molecular function of ion channels that are involved in the control and regulation of calcium-release from intracellular stores. The aim of our research is to try to understand what happens to channel function under pathophysiological conditions.
We currently have two main areas of research:
1. Elucidating the molecular mechanisms of NAADP-regulated signalling via Two Pore Channels
Recent research has discovered that a biological agent called “nicotinic acid dinucleotide phosphate” (NAADP) causes the release of calcium by opening a newfamily of pore forming proteins called two pore channels (TPCs) located on acidic intracellular calcium stores. The mechanism of NAADP-regulated signalling via TPCs is not well understood. In humans there are two isoforms of TPC (TPC1 and TPC2) and we are currently investigating the single-channel behaviour of these putative Ca2+-release channels. Owing to their Ca2+-handling properties aberrant TPC function may impact on diseases where disruption of Ca2+-signals are central, including cytotoxicity and cell death, heart failure, and neurodegenerative processes. Furthermore, genetic studies have linked the gene coding TPC2 to hearing defects and cancer.Understanding the role of TPCs in regulating calcium-release will enable the design of drugs that can manipulate the release of calcium via these channels and help combat diseases associated with abnormal calcium-movements.
2. Understanding new mechanisms of cardiac ryanodine receptor regulation by zinc
We are also interested in how Zn2+ modulates Ca2+-signalling in the heart. Aberrant Zn2+-homeostasis is a hallmark of certain cardiomyopathies associated with altered contractile force and is likely a consequence of altered excitation-contraction coupling. How Zn2+ impacts upon the contractile force and the release of Ca2+ from intracellular stores in cardiac muscle is unknown. Our latest findings suggest that physiological concentrations of Zn2+ modify the function of the cardiac ryanodine receptor Ca2+-release channel (RyR2) and that this change in channel gating may be a major contributor to the generation of cardiac arrhythmias. We are currently investigating at the single-channel level the mechanisms of how Zn2+ regulates RyR function.
- Professor Antony Galione – Department of Pharmacology, University of Oxford
- Dr Richard Rainbow – Department of Cardiovascular Sciences, University of Leicester
- Professor Rebecca Sitsapesan – Department of Pharmacology, University of Oxford
- SJP is supported by a Royal Society of Edinburgh Biomedical Personal Fellowship
- Our research is funded by Tenovus Scotland and the British Heart Foundation
4 (of 4 published available) for sjp24 with keyword Calcium-release clear keyword filter. (source: University of St Andrews PURE)
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Biochemical Society Transactions
Samantha Jane Pitt, Alan J. Stewart
Keywords: Zinc, Ryanodine receptor, Excitation Contraction Coupling, Calcium Dynamics
Journal of Biological Chemistry
Elisa Venturi, Elena Galfre, Fiona O'Brien, Samantha Jane Pitt, Stuart Bellamy, Richard B. Sessions, Rebecca Sitsapesan
Keywords: Calcium-release channel, Cardiac ryanodine receptor, Muscle sarcoplasmic-reticulum, Skeletal-muscle, FK506-binding protein, Heart-failure, Defective regulation, Selective binding, Cytoplasmic ca2+, Leak
Elena Galfre, Samantha Jane Pitt, Elisa Venturi, Mano Sitsapesan, Nathan R Zaccai, Krasimira Tsaneva-Atanasova, Stephen O'Neill, Rebecca Sitsapesan
Keywords: Calcium-release channel, FKBP, Heart disease, Arrhythmia