Identification of lysosomal sialidase NEU1 and plasma membrane sialidase NEU3 in human erythrocytes.
The sialylation level of molecules, sialoglycoproteins and gangliosides, protruding from plasma membranes regulates multiple facets of erythrocyte function, from interaction with endothelium to cell lifespan. Our results demonstrate that: (a) Both sialidases NEU1 and NEU3 are present on erythrocyte plasma membrane; (b) NEU1 is kept on the plasma membrane in absence of the protective protein/cathepsin A (PPCA); (c) NEU1 and NEU3 are retained on the plasma membrane, as peripheral proteins, associated to the external leaflet and released by alkaline treatments; (d) NEU1 and NEU3 are segregated in Triton X-100 detergent-resistant membrane domains (DRMs); (e) NEU3 shows activity also at neutral pH; and (f) NEU1 and NEU3 are progressively lost during erythrocyte life. Interestingly, sialidase activity released from erythrocyte membranes after an alkaline treatment preserves its functionality and recognizes sialoglycoproteins and gangliosides. On the other hand, the weak anchorage of sialidases to the plasma membrane and their loss during erythrocyte life could be a tool to preserve the cellular sialic acid content in order to avoid the early ageing of erythrocyte and processes of cell aggregation in the capillaries.
Department of Medical Chemistry, Biochemistry and Biotechnology, University of Milan, F.lli Cervi 93, Segrate, Milan 20090, Italy.
Francesca
F
D'Avila
Cristina
C
Tringali
Nadia
N
Papini
Luigi
L
Anastasia
Gianluigi
G
Croci
Luca
L
Massaccesi
Eugenio
E
Monti
Guido
G
Tettamanti
Bruno
B
Venerando
D015153:Blotting, Western; D002458:Cell Fractionation; D002462:Cell Membrane / Q000737:chemistry / Q000201:enzymology*; D016922:Cellular Senescence / Q000502:physiology; D003600:Cytosol / Q000737:chemistry / Q000201:enzymology*; D004912:Erythrocytes / Q000737:chemistry / Q000201:enzymology*; D005732:Gangliosides / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008247:Lysosomes / Q000737:chemistry / Q000201:enzymology*; D009439:Neuraminidase / Q000378:metabolism*; D017830:Octoxynol / Q000737:chemistry; D012794:Sialic Acids / Q000378:metabolism
D005732:Gangliosides; D012794:Sialic Acids; D017830:Octoxynol; C486385:NEU1 protein, human; C465436:Neu3 protein, human; D009439:Neuraminidase