Grant: Project Grant

Cell division is the basic mechanism by which multicellular organisms reproduce, grow, and heal. Over the lifetime of a human, cell division will occur ~10^16 times, yielding perfect copies almost every time. The astonishingly low error rate is due to structures called spindles, which function to distribute genetic material evenly among the daughter cells. Yet despite their ubiquity and importance in biology and diseases, how these spindles self-assemble is not known. We recently hypothesize that spindle assembly requires the formation of focal hotspots of calcium called calcium nanodomains, which have so far escaped detection due to poor spatial resolution of traditional calcium imaging techniques. We have now developed a novel probe called TubeCamp which can localize calcium increase to 250nm. We are able to resolve, for the first time, the formation of nanodomains associated with spindle self-assembly in both vertebrate cells and cell-free cytoplasm aspirates. Furthermore, disruption of calcium nanodomains disrupts spindles. These results prove that calcium nanodomains are indeed a universal and essential feature of spindles in vertebrates. We propose to identify key components of calcium anodomains, and to provide insights on how they work together to regulate spindle ssembly. Microtubule-targeting agents are the most important cancer chemotherapy drugs. Loss of microtubules is thought to be an important contributing factor in neurodegenerative diseases; clinically approved microtubule stabilizing epothilones have shown promise in animal models of Alzheimer, Parkinson and spinal cord injuries. Our work has revealed a previously unsuspected mechanism of microtubule regulation. This mechanism is unlikely restricted to spindle microtubules, as calcium-storing membranes have been observed in close association with microtubules in neurons. Our work may thus have wide implications in human health and diseases including cancers and neurodegenerative diseases.