Membrane assembly during erythropoiesis

Purpose of review In this review, we summarize our current knowledge on the expression patterns of various proteins during erythropoiesis and discuss how this information can lead to development of detailed understanding of membrane biogenesis during erythropoiesis. Recent findings Changes in expression pattern of more than 30 red cell membrane proteins during terminal erythroid differentiation and during reticulocyte maturation was discerned. During maturation of murine reticulocytes, tubulin and cytosolic actin were lost, while the membrane-associated levels of myosin, tropomyosin, ICAM-4, GLUT4, Na/K-ATPase, NHE1, GPA, CD47, Duffy, and Kell were reduced. During murine terminal erythroid differentiation, expression levels of all major transmembrane and skeletal proteins of the mature red blood cell increased, while those of various adhesion molecules decreased. A 30-fold decrease in expression of the adhesive protein CD44 was noted during differentiation of murine proerythroblast to orthochromatic erythroblast. These changing protein expression patterns were used to devise an effective strategy to distinguish erythroblasts at distinct stages of development. Summary All major red cell membrane proteins undergo dynamic changes during terminal erythroid differentiation. Use of CD44 in conjunction with TER119 and cell size enabled the development of a method for distinguishing distinct stages of erythroblasts during murine erythropoiesis. These findings should enable development of detailed understanding of membrane biogenesis during erythropoiesis and obtain mechanistic insights into disordered erythropoiesis in various red cell disorders.