The outermost cells that line blood vessels, lungs, and other organs also act like guards, alert and ready to thwart pathogens, toxins, and other invaders that can do us harm. Called epithelial cells, they don’t just lie passively in place. Instead, they communicate with each other and organize their internal structures in a single direction, like a precisely drilled platoon of soldiers lining up together and facing the same way.
Lining up this way is crucial during early development, when tissues and organs are forming and settling into their final positions in the developing body. In fact, failure to line up in the correct way is linked to numerous birth defects. In the lungs, for instance, epithelial cells’ ability to synchronize with one another is important since these cells have special responsibilities such as carrying mucus up and out of lung tissue. When these cells can’t coordinate their functions, disease results.
Some lung epithelial cells are covered in many tiny, hair-like structures called cilia. All the cilia on lung epithelial cells must move uniformly in a tightly choreographed way to be effective in their mucus-clearing job. This is a unique example of a process called planar cell polarity (PCP) that occurs in cells throughout the body. Researchers are seeking to identify the signals cells use to implement PCP. Continue reading