Japanese Journal of Veterinary Research;Volume 58, Number 1

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Extrusion of Na,K-ATPase and transferrin receptor with lipid raft-associated proteins in different populations of exosomes during reticulocyte maturation in dogs

Komatsu, Tomohiko;Arashiki, Nobuto;Otsuka, Yayoi;Sato, Kota;Inaba, Mutsumi

Permalink : http://hdl.handle.net/2115/43054
JaLCDOI : 10.14943/jjvr.58.1.17
KEYWORDS : dog;exosome;Na,K-ATPase;reticulocyte;stomatin

Abstract

The present study characterizes canine reticulocyte exosomes. Exosomes are small membrane vesicles involved in membrane remodeling that are released from reticulocytes during the final maturation step of red blood cells. The vesicles collected from reticulocyte culture supernatants by differential centrifugation contained major exosomal proteins including heat shock protein cognate 70 (Hsc70) and transferrin receptors (TfR), consistent with the definition of the exosome. In addition, the Na,K-ATPase α-subunit and stomatin, a lipid raft-associated protein, were extruded by the exosome pathway, possibly leading to the absence of these proteins in erythrocytes, while the major protein constituents of erythrocyte membranes, spectrin and band 3 were retained in reticulocytes and not expelled into exosomes. The Na,K-ATPase α-subunit, as well as TfR and about half of the stomatin contained in exosomes, was obtained in a detergent-soluble fraction that was distinct from the lipid raft microdomain. Moreover, Na,K-ATPase and a portion of stomatin were distributed differently to Hsc70, TfR, stomatin, and ganglioside Gm1 in vesicles separated with sucrose density gradient centrifugation. These results demonstrate that a heterogeneous group of exosomes participates in the loss of Na,K-ATPase and membrane remodeling during reticulocyte maturation in dogs.

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