Elongation by contraction

From National University of Singapore:

Scientists from the Mechanobiology Institute (MBI) at the National University of Singapore (NUS) have discovered a new mechanism of cell boundary elongation. Elongation and contraction of the cell boundary is essential for directing changes in cell shape, which is required for the correct development of tissues and organs. The study was published in Current Biology on 11 August 2016.

How do contractile forces lengthen cell boundaries?

During development of an embryo, cells assemble to form tissues and organs. This requires cells to grow, divide, and occasionally undergo programmed death. However, a common property observed in many of these biological processes is cell deformation, which is essentially a dynamic change in cell shape. Based on mechanical principles, these shape changes have been broken down as either a contraction or elongation of the cell boundary. Cell boundary contraction has been extensively studied, and is driven by contraction of a network of protein filaments within the cell. The two major components of this contractile network are actin, a structural protein that forms long filaments or cables, and myosin II, a motor protein that binds to actin and uses energy to slide the actin filaments past each other. Known as actomyosin, this network is responsible for generating contractile force in cells.

As actomyosin contraction is a “pulling” force, it is easy to visualise how activity of this network can pull in the cell boundaries, causing contraction. However, as the actomyosin network is unable to generate the opposite “pushing” force, scientists have long sought to answer the question of how do cell boundaries elongate.

In order to answer this question, MBI researchers Associate Professor Yusuke Toyama, who is the Principal Investigator of the research, and Dr Yusuke Hara, together with Mr Murat Shagirov, who was formerly a researcher at the Institute, used live embryo …

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