Abstract 4028: A consolidated microplate-based workflow for monitoring intracellular calcium mobilization and mitochondrial membrane potential changes

Abstract

Abstract The interactions between mitochondrial function and Ca2+ homeostasis are very complex. Mitochondria are known to serve as dynamic calcium storage compartments, and also form intimate contacts with other calcium-handling organelles, such as the endoplasmic reticulum. Calcium enters mitochondria, not only during pathological processes, but also during physiological calcium responses. This organelle does not simply passively buffer excessive calcium but actively utilizes calcium signals to regulate integral cell activities, such as oxidative phosphorylation and the Kreb's cycle. A consolidated microplate-based workflow is described for assessing the relationship between mitochondria and global calcium responses. Two novel small molecule probes were implemented in the assay. Mitochondrial membrane potential was monitored using a dual-emission fluorescent probe that is roughly 10-25-fold more sensitive than the conventional carbocyanine dye, JC-1. Calcium mobilization was examined using a novel fluorescent calcium indicator dye that is significantly brighter than Fluo-4 AM dye. The assay is readily performed using a fluorescence microplate reader equipped with a dual-reagent dispenser. Proof-of-principle studies were performed by evaluating cell response to two agents, diazoxide, a putative opener of the potassium-ATP channel, and BML-258, a novel sphingosine kinase-1 inhibitor. The assay workflow is suitable for monitoring calcium mobilization and mitochondrial membrane potential changes across a broad spectrum of biological targets. The easy-to-use protocol is automation-friendly and can be performed in a convenient 96-well or 384-well microplate format. The assay should provide insight into the interaction between calcium signaling and mitochondrial energetic status, relevant to a range of phenomena, including ischemia/reperfusion injury. It should also serve as a high-throughput approach for identifying specific small molecule pharmacological agents targeted to this complex interrelationship. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4028.