Current Biology
Volume 8, Issue 12, 4 June 1998, Pages 692-700
Journal home page for Current Biology

Research Paper
Imaging the spatial dynamics of calmodulin activation during mitosis

https://doi.org/10.1016/S0960-9822(98)70275-1Get rights and content
Under an Elsevier user license
open archive

Abstract

Background: Calcium is an important and ubiquitous signalling ion. In most cell types, changes in intracellular calcium concentrations are sensed by calmodulin, a signal transduction protein that regulates cell function through its interactions with kinases and phosphatases. Calcium signals show complex spatiotemporal patterning, but little, if anything, is known about the patterns of calmodulin activation inside cells.

Results: We have measured calmodulin activation continuously during mitosis in living cells with a new probe, a fluorescent adduct of calmodulin termed TA–calmodulin. We found that calmodulin was activated locally and episodically in the nucleus and mitotic spindle. The pattern of calmodulin activation was different from the pattern of calcium signals and could not be predicted from the pattern of calcium increase. Calmodulin activation was essential for mitotic progression: both entry into mitosis and exit from mitosis were blocked by a novel peptide that bound to calmodulin with high affinity and so prevented the interaction of calmodulin with its target proteins.

Conclusions: These data suggest that calmodulin regulates mitotic transitions and demonstrate the utility of fluorescent adducts for studying protein activation in living cells with good temporal and spatial resolution.

Cited by (0)

K Török, M Wilding, L Groigno, R Patel and M Whitaker, Department of Physiological Sciences, University of Newcastle, Medical School, Framlington Place, Newcastle upon Tyne NE2 4HH, UK.

Present address for K Török, School of Biological Sciences, Queen Mary & Westfield College, University of London, London E1 4NS, UK.

Present address for M Wilding, Stazione Zoologica, Villa Comunale, 1, 80121 Naples, Italy.

Present address for R Patel, Department of Biochemistry, University of Leicester, Leicester, UK.

E-mail address for M Whitaker (corresponding author), [email protected].