Janitorial system in red blood cells discovered

Abstract

Red blood cells are a stripped-down version of most other cells: The oxygen-carrying workhorses are packed with hemoglobin and little else. As immature red blood cells called reticulocytes transform into dedicated oxygen carriers, they trash their nucleus, organelles, and most proteins. Two groups of scientists are now reporting that this massive and selective clearance event occurs thanks to a protein degradation pathway involving an enzyme called UBE2O. A team led by Daniel Finley and Mark D. Fleming at Harvard Medical School report that in the last stages of red blood cell differentiation, UBE2O remodels the proteome inside reticulocytes by tagging the small protein ubiquitin onto protein “trash” to signal for its breakdown, leaving the cell with approximately 98% α- and β-globin, the subunits that join to form hemoglobin (Science 2017, DOI: 10.1126/science.aan0218). Meanwhile, Ramanujan S. Hegde and his team at the Medical Research Council Laboratory of Molecular Biology in Cambridge,