Another link between phospholipid transmembrane migration and ABC transporter gene family, inferred from a rare inherited disorder of phosphatidylserine externalization.
The mechanisms involved in the maintenance or loss of the asymmetric distribution of phospholipids in the cell plasma membrane remain mysterious. In the yeast Saccharomyces cerevisiae, the transmembrane migration of certain phospholipids is controlled by transcription regulators of various ATP-binding cassette (ABC) transporters. The P-glycoprotein membrane transporters encoded by the multidrug resistance (MDR) genes, members of the ABC protein family, act as lipid translocases in mammalian cells. We report here the lack of expression of MDR genes in lymphoblasts derived from the B cells of a patient with an inherited Scott syndrome, characterized by impaired transmembrane migration of procoagulant phosphatidylserine and hemorrhagic complications. From microsatellite analysis of 7q21.1 and functional assessment, the most likely explanation accounting for Scott phenotype is a mutation in an unlinked gene coding for a regulatory protein necessary for the expression of MDR genes. Because phosphatidylserine externalization is also one of the hallmarks of cells undergoing apoptosis, these observations are suggestive of a relationship between basic processes such as multidrug transport, apoptosis and procoagulant phospholipid exposure.
Toti
F
F
Institut d'Hématologie et d'Immunologie, Faculté de Médecine, Université Louis Pasteur, Strasbourg, France.
Schindler
V
V
Riou
J F
JF
Lombard-Platet
G
G
Fressinaud
E
E
Meyer
D
D
Uzan
A
A
Le Pecq
J B
JB
Mandel
J L
JL
Freyssinet
J M
JM
D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis; D018528:ATP-Binding Cassette Transporters / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D000368:Aged; D001692:Biological Transport; D002352:Carrier Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002897:Chromosomes, Human, Pair 7; D018432:Drug Resistance, Multiple; D015870:Gene Expression; D019450:Genes, MDR; D005819:Genetic Markers; D006801:Humans; D008052:Lipid Metabolism, Inborn Errors / Q000235:genetics* / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D018895:Microsatellite Repeats; D010718:Phosphatidylserines / Q000378:metabolism*; D049294:Phospholipid Transfer Proteins
D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D018528:ATP-Binding Cassette Transporters; D002352:Carrier Proteins; D005819:Genetic Markers; D008565:Membrane Proteins; D010718:Phosphatidylserines; D049294:Phospholipid Transfer Proteins; C095122:multidrug resistance protein 3