Monday, October 10, 2016

Packaging without packets! Interview with Shamba Saha on membrane-less organization within cells!!

How do you organize your stuff at home. In boxes, I suppose. Tucked into boxes, all the stuff is nicely arranged. This is not special to human behavior, as even biological cells use the same principle of compartmentalization! They organize the information source (DNA) into nucleus, making it efficient to read and copy. They put all energy forming apparatus into units called mitochondria. They organize garbage disposal into chambers called lysosomes. But the beauty and complexity of biological systems doesn't stop there! They go one step further and aggregate developmentally important and dynamic stuff into structures that lack a membranous boundary; essentially packaging biological entities without an overt packet!

How do they achieve such a feat. Shamba and colleagues try to answer this question by looking at the formation of germline defining particles, the P-bodies, in a worm, C. elegans. These non-membranous compartment, they find, are generated by an striking process called phase-separation, just like oil droplets form when mixed with water! But these bodies are much more than passive emulsions, and are a complex mix of RNA and protein dynamically interacting with the surroundings!! What is even more striking, and beautiful, is that these do not form randomly, but are localized to one area of the cell. How many components are needed to make such a complex biological process?? Listen to Shamba to know that the real beauty in the system is its simplicity, as only one (ONE!!!) protein is enough to generate these structures, and a very small network to regulate it.



To know more about the work, please refer to the following publication:
Polar Positioning of Phase-Separated Liquid Compartments in Cells Regulated by an mRNA Competition Mechanism
Saha et al., Cell. Volume 166, Issue 6, p1572–1584.

Also, you can see a video abstract on the topic here:
Phase separation in cell polarity
  

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