September 13, 2018

How microvilli form

A protein called IRTKS helps build the microvilli that form the border of cells in the intestines, explaining why the protein is a frequent target of gut pathogens.

by Sanjay Mishra

The gut is lined by cells containing brush borders, which are composed of arrays of microvillar protrusions that help in nutrient absorption and provide a barrier against pathogens and toxins. Microbes such as E. coli can destroy microvilli with potentially life-threatening results. But how microvilli form has not been well understood.

Using super-resolution microscopy and live cell imaging, Matthew Tyska, PhD, and colleagues show that a protein called insulin receptor tyrosine kinase substrate (IRTKS) promotes microvilli elongation. They previously discovered that IRTKS is the only protein in the intestinal brush border containing an I-BAR domain. I-BAR proteins help form membrane protrusions.

Reporting this month in the journal Current Biology, the researchers showed that IRTKS tracks to the distal tips of growing microvilli through the I-BAR domain. These results help explain why IRTKS is targeted by the gut pathogens that disrupt microvilli during infection of the intestinal lining.

This work was supported in part by National Institutes of Health grants DK075555, DK111949 and DK095811.