The MAL proteolipid is necessary for normal apical transport and accurate sorting of the influenza virus hemagglutinin in Madin-Darby canine kidney cells.
The MAL (MAL/VIP17) proteolipid is a nonglycosylated integral membrane protein expressed in a restricted pattern of cell types, including T lymphocytes, myelin-forming cells, and polarized epithelial cells. Transport of the influenza virus hemagglutinin (HA) to the apical surface of epithelial Madin-Darby canine kidney (MDCK) cells appears to be mediated by a pathway involving glycolipid- and cholesterol- enriched membranes (GEMs). In MDCK cells, MAL has been proposed previously as being an element of the protein machinery for the GEM-dependent apical transport pathway. Using an antisense oligonucleotide-based strategy and a newly generated monoclonal antibody to canine MAL, herein we have approached the effect of MAL depletion on HA transport in MDCK cells. We have found that MAL depletion diminishes the presence of HA in GEMs, reduces the rate of HA transport to the cell surface, inhibits the delivery of HA to the apical surface, and produces partial missorting of HA to the basolateral membrane. These effects were corrected by ectopic expression of MAL in MDCK cells whose endogenous MAL protein was depleted. Our results indicate that MAL is necessary for both normal apical transport and accurate sorting of HA.
Puertollano
R
R
Centro de Biología Molecular "Severo Ochoa," Universidad Autónoma de Madrid and Consejo Superior de Investigaciones Científicas, Cantoblanco, Madrid, Spain.
Martín-Belmonte
F
F
Millán
J
J
de Marco
M C
MC
Albar
J P
JP
Kremer
L
L
Alonso
M A
MA
D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects; D016764:Cell Polarity; D003902:Detergents / Q000494:pharmacology; D004285:Dogs; D004847:Epithelial Cells / Q000378:metabolism; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000378:metabolism*; D007668:Kidney; D008563:Membrane Lipids / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D026901:Membrane Transport Proteins; D009185:Myelin Proteins; D062806:Myelin and Lymphocyte-Associated Proteolipid Proteins; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D011510:Proteolipids / Q000037:antagonists & inhibitors / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D014162:Transfection
D000911:Antibodies, Monoclonal; D003902:Detergents; D019267:Hemagglutinin Glycoproteins, Influenza Virus; C569028:Mal protein, rat; D008563:Membrane Lipids; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D009185:Myelin Proteins; D062806:Myelin and Lymphocyte-Associated Proteolipid Proteins; D016376:Oligonucleotides, Antisense; D011510:Proteolipids; C109963:hemagglutinin, avian influenza A virus