#actomyosin

Stress Lines

Walking in a straight line with your eyes closed is surprisingly tricky. So how do cells navigating dark depths of the body keep on track? These essential journeys, fundamental to healthy development, are enabled by stress fibres – bundles of proteins that anchor and guide a cell’s movement. How these stress fibres manoeuvre is poorly understood. A new study observed cell movement in a fruit fly egg chamber and discovered the fibres steer progress through a conveyor-belt mechanism, growing new material at their leading tip and laying down fresh sticky segments one in front of the other (video, with growing tips in blue). Adhesion at the back is dismantled as the rear of the cell catches up. The researchers identified a key regulator, a protein called DAAM, that supports this on-the-move growth, and showed this constant treadmill keeps each cell on a steady trajectory, and on course for a healthy life.

Written by Anthony Lewis

Video by Kristin M Sherrard, Maureen Cetera and Sally Horne-Badovinac

Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL, USA

Video originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)s

Published in eLife, November 2021

Watch a wound close with the help of fat cells

In the Band

Wrapping like a band around the inside of human cells, the actomyosin cortex contracts and expands to pull them into shape – preparing for important activities like cell division. Yet the molecules involved – actin (highlighted in green), and myosin (purple) aren’t always band-mates. Using a technique called STORM imaging, researchers picture cross-sections through these cells at different stages of life, revealing the cortex in white, where myosin and actin overlap. Yet in the younger cell (right) some of the purple myosin has pulled away from the cortex. Researchers believe that the size of bulky myosin molecules influences how and where it twangs back to the actin and re-joins the cortex. This form of steric hindrance may help to control a cell’s shape, and could be influenced in dividing cells, like the one on the left, to treat various forms of cancer.

Written by John Ankers

Image adapted from work by Binh An Truong Quang and Ruby Peters, and colleagues

MRC Laboratory for Molecular Cell Biology, University College London, London, UK

Image originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)

Published in Nature Communications, November 2021