心肌钙稳态的调控和失衡的生理和病理机制

Ca2+是最古老、作用最广泛的细胞信使物质，其稳态是机体正常功能调控的前提，其失衡则是很多疾病的关键原因。目前钙稳态研究仍以测定胞内钙浓度变化的现象为主，在阐述其机制时又与钙通道的信号转导功能界定不清，限制了钙稳态分子机制的深入研究和其失衡机制的精准揭示。本项目基于申请人长期从事钙信号和钙稳态研究的积累，提出了心肌细胞钙稳态分子机制研究的定量指标体系，其中包括原创性地设计了在完整细胞中研究钙稳态关键分子ryanodine受体静息侧(R端)激活性质的实验方法，以及对细胞膜钙通道、钠钙交换和肌质网钙泵的定量测定。本项目将用此定量指标体系研究不同β肾上腺素受体(βAR)亚型和肌质网calsequestrin对钙稳态的调控机制、βAR和calsequestrin突变联合导致致死性心律失常的钙稳态失衡机制，以及冬眠动物心肌细胞加强钙稳态的适应性机制，结合系统建模，整合实验数据，证明钙稳态调控新理论。

Ca2+ is the most prototypical and versatile intracellular messenger. While calcium homeostasis is the prerequisite for cell function, calcium dysregulation is a key cause of diseases. Current study of calcium homeostasis relies on phenomenal measurements of intracellular calcium concentration with confusions between calcium homeostasis and calcium signaling, which limits the precise understanding of the molecular mechanisms and dysregulation of calcium homeostasis. Base on long-term studies of calcium signaling and calcium homeostasis, we postulate a set of parameters for quantifying the molecular components of calcium homeostasis in cardiomyocytes, including a newly designed experimental protocol for quantifying the resting-state activation of ryanodine receptors, as well as protocols for measuring cell membrane calcium channels, Na/Ca exchangers and sarcoplasmic reticulum calcium pumps. Utilizing this parameter set, we will investigate the mechanisms underlying the β-adrenergic regulation and calsequestrin modulation of calcium homeostasis, the calsequestrin mutation-induced calcium dysregulation in lethal arrhythmias, and the enhanced calcium homeostatic capacity in hibernator cells. Novel hypothesis of calcium homeostasis will be tested by combining model simulations and experimental results.