Multivesicular bodies and autophagy in erythrocyte maturation.
During reticulocyte maturation, hematopoietic progenitors undergo numerous changes to reach the final functional stage which concludes with the release of reticulocytes and erythrocytes into circulation. During this process some proteins, which are not required in the mature stage, are sequestered in the internal vesicles present in multivesicular bodies (MVBs). These small vesicles are known as exosomes because they are released into the extracellular medium by fusion of the MVB with the plasma membrane. Interestingly, during this maturation process some organelles, such as mitochondria and endoplasmic reticulum, are wrapped in double membrane vacuoles and degraded via autophagy. We have demonstrated in human leukemic K562 cells a role for calcium and Rab11 in the biogenesis of MVBs and exosome release. Here we discuss evidence indicating that K562 cells present a high basal level of autophagy, and that there is an association between MVBs and autophagosomes, suggesting a role for the autophagic pathway in the maturation process of this cell type.
Fader
Claudio M
CM
Laboratorio de Biología Celular y Molecular, Instituto de Histología y Embriología IHEM-CONICET, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina.
Colombo
María I
MI
D000818:Animals; D001343:Autophagy / Q000502:physiology*; D016466:CHO Cells; D002118:Calcium / Q000502:physiology; D002462:Cell Membrane / Q000502:physiology; D006224:Cricetinae; D003412:Cricetulus; D004721:Endoplasmic Reticulum / Q000502:physiology; D011992:Endosomes / Q000502:physiology; D004912:Erythrocytes / Q000502:physiology*; D004920:Erythropoiesis / Q000502:physiology*; D006801:Humans; D020014:K562 Cells; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D008928:Mitochondria / Q000502:physiology; D015388:Organelles / Q000502:physiology*; D012156:Reticulocytes / Q000502:physiology; D020691:rab GTP-Binding Proteins / Q000502:physiology; D000099193:rab11 GTP-Binding Proteins
D002118:Calcium; D008869:Microtubule-Associated Proteins; D020691:rab GTP-Binding Proteins; D000099193:rab11 GTP-Binding Proteins; C477012:MAP1LC3A protein, human