How cells get a skeleton

Jun 10, 2013

The mechanism responsible for generating part of the skeletal support for the membrane in animal cells is not yet clearly understood. Now, Jean-François Joanny from the Physico Chemistry Curie Unit at the Curie Institute in Paris and colleagues have found that a well-defined layer beneath the cell outer membrane forms beyond a certain critical level of stress generated by motor proteins within the cellular system. These findings, which offer a new understanding of the formation of this so-called cortical layer, have just been published in the European Physical Journal E.

Active gels are ideal for modelling the similar material found in living cells' structure, made of a dynamic, filamentous scaffold. They are composed of components that take up energy and do directed work. Indeed, is fed into the cells' constituents and is transformed into mechanical work through the assembly of its internal filaments, made of a polymer called actin, and a protein that functions as a , called myosin. Both provide the active gel-like substance found in cells with a spontaneous tendency to contract. As a result, the cells can either maintain or change their shape, or even adhere, spread, divide and crawl.

In this study, the authors have created hydrodynamic models of active gels to model the cell cortex, whereby the active gel is polymerising at the surface and depolymerising throughout the gel as a whole. They first derived the equations providing a coarse-grained description of cortical dynamics, then calculated the configuration in which their model was in a steady state.

They found that for sufficiently high levels of contractile stress it consisted of a dense layer near the membrane, which abruptly cut off beyond a certain thickness. The key advance in their model is the inclusion of gel disassembly throughout the system, and the contractility due to molecular motors.

Explore further: Cold improves longevity for some C. elegans worms, shortens life span for others

More information: J.-F. Joanny et al. (2013), The actin cortex as an active wetting layer, European Physical Journal E. DOI 10.1140/epje/i2013-13052-9

Related Stories

Scientists build 'mechanically active' DNA material

Oct 23, 2012

Artificial muscles and self-propelled goo may be the stuff of Hollywood fiction, but for UC Santa Barbara scientists Omar Saleh and Deborah Fygenson, the reality of it is not that far away. By blending their ...

Make or break for cellular tissues

May 16, 2012

In a study about to be published in the European Physical Journal E, French physicists from the Curie Institute in Paris have demonstrated that the behaviour of a thin layer of cells in contact with an unfavourable substr ...

Recommended for you

Understanding how cells follow electric fields

19 hours ago

Many living things can respond to electric fields, either moving or using them to detect prey or enemies. Weak electric fields may be important growth and development, and in wound healing: it's known that ...

Protein scaffold

May 27, 2015

Right before a cell starts to divide to give birth to a daughter cell, its biochemical machinery unwinds the chromosomes and copies the millions of protein sequences comprising the cell's DNA, which is packaged ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.