Thursday, 05 July, 2012
Easy come, easy go
New insights into the life of microtubules
Every second, around 25 million cell divisions take place in our bodies. This process is driven by microtubule filaments which continually grow and shrink. Now a study shows how so-called motor proteins from the cytosol can controll this dynamic.
The cytoskeleton plays a primary role during cell division. It is composed in large part of protein filaments known as microtubules, which also help determine the size, shape and mobility of a cell. In a new study, Prof. Erwin Frey, biophysicist at the LMU München, and his colleagues Dr. Anna Melbinger and Louis Reese used a theoretical model to show how cells control the construction and breakdown of the microtubules. The dynamics of this process affect how cells divide and how they maintain the cytoskeleton. In particular, it is responsible for the regulation of size and shape of the mitotic spindle.
Theoretical modeling now revealed that length-regulation of the microtubules relies on the length of the filament itself: The longer the filament the more motor proteins can attach along. They all move towards the ‘plus end’ of the microtubule and thereby accumulate. Upon arrival at the plus-end they shorten the filament. In parallel, new microtubule building blocks bind to precisely the same ‘plus end’ through spontaneous polymerization from the surrounding cytosol, and the filament grows. It was now demonstrated that such interplay between growth and length-dependent shrinkage, does result in a precisely regulated microtubule length. This kind of length regulation might be essential for many intracellular tasks which rely on microtubules of a certain length.
This work was supported by the Cluster of Excellence „Nanosystems Initiative Munich (NIM)” and the SFB 863 Forces in Biomolecular Systems.
See also article in Nature - Research Highlights: "How cells maintain chains". Nature 487, 9, Published online 04 July 2012
Microtubule Length-Regulation by Molecular Motors.
Anna Melbinger, Louis Reese, and Erwin Frey. Phys. Rev. Lett. 108, 258104 (2012). Published online June 22, 2012
Focus articel in „Physics“:
How Cells Regulate the Length of Filaments. Don Monroe (freelance science writer).
Physics 5, 69 (2012). Published June 22, 2012. http://physics.aps.org/articles/v5/69
Prof. Dr. Erwin Frey
Ludwig-Maxmilians-Universität (LMU) München
Lehrstuhl für Statistische und Biologische Physik
Arnold-Sommerfeld-Center für Theoretische Physik, Center for NanoScience (CeNS) und Exzellenzcluster Nanosystems Initiative Munich (NIM)
Tel.: 089 / 2180 – 4537
Fax: 089 / 2180 – 4538
Wikimedia, Public domain, http://de.wikipedia.org/wiki/Benutzer:Jan_R
Fluorescently labeled endothelial cells. Microtubles are marked green, nuclei are stained blue, and actin filaments are labeled red.