Certain groups of these white blood cells, now known as neutrophils, feature a nucleus that is structured strikingly different than most nuclei. The majority of cells feature round- or oval-shaped nuclei that are rigid, but neutrophils differ in that their nuclei adopt multiple lobular structures akin to that of flower petal arrangements. These unique nuclear shapes permit neutrophils to travel all over the body to identify and combat invading pathogens.

 

Reporting in Nature, University of California San Diego School of Biological Sciences Postdoctoral Scholar Indumathi Patta and Professor Cornelis Murre, in collaboration with Dr. Ming Hu at the Cleveland Clinic Foundation, have deciphered the shapeshifting puzzle of the neutrophil nucleus. Using a combination of ancient staining procedures combined with advanced techniques, named chromosome-conformation-capture studies, the researchers unveiled how flower-like nuclei are assembled. While chromosomes of rounded cells fold into stacked bundles of DNA loops, neutrophil genomes lack such loops.

 

Remarkably, when the researchers removed chromatin loops, progenitor cells swiftly converted round nuclear shapes into flower petal arrangements like those found in neutrophils. This simple conversion also sufficed to activate thousands of genes associated with an inflammatory gene program that allows neutrophils to combat invading bacteria. After unveiling the neutrophil loop assembly question, the researchers now believe they have the instructions to guide the development of new nuclear shapes.