Glycosylphosphatidylinositol-anchor-deficient mice: implications for clonal dominance of mutant cells in paroxysmal nocturnal hemoglobinuria.
Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired hematopoietic stem cell disorder characterized by complement-mediated hemolysis. Abnormal hematopoietic cells from patients with PNH are deficient in glycosylphosphatidylinositol (GPI)-anchored proteins and clonally dominate various hematopoietic lineages in the bone marrow and the peripheral blood. Analysis of many patients with PNH has showed that somatic mutation in the X-linked gene PIG-A is responsible for the GPI-anchor deficiency in PNH. The PIG-A mutation must also be relevant to the clonal dominance of GPI-anchor deficient (GPI-) blood cells because two or more PIG-A mutant clones become dominant in many patients. However, whether the PIG-A mutation alone is sufficient for clonal dominance is not known. To address this question, we generated chimeric mice using Pig-a (the murine homologue of PIG-A) disrupted embryonic stem (ES) cells, in which the animals are chimeric with respect to the surface expression of GPI-anchored proteins. The chimerism of hematopoietic and nonhematopoietic tissues in such mice was always low, suggesting that the higher contribution of Pig-a disrupted GPI- cells had a lethal effect on the chimera. GPI- cells appeared in the peripheral blood of some of the chimeric mice. However, the percentage of GPI- erythrocytes did not increase for 10 months after birth, implying that the Pig-a mutation alone does not immediately cause the clonal dominance of GPI- blood cells; another pathologic or physiologic change(s) in the hematopoietic environments or in the clone itself may be necessary.
Kawagoe
K
K
Department of Immunoregulation, Osaka University, Japan.
Kitamura
D
D
Okabe
M
M
Taniuchi
I
I
Ikawa
M
M
Watanabe
T
T
Kinoshita
T
T
Takeda
J
J
D000818:Animals; D001483:Base Sequence; D002999:Clone Cells; D005799:Genes, Dominant; D017261:Glycosylphosphatidylinositols / Q000172:deficiency* / Q000235:genetics; D006410:Hematopoiesis / Q000235:genetics*; D006457:Hemoglobinuria, Paroxysmal / Q000235:genetics* / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008817:Mice, Mutant Strains; D008969:Molecular Sequence Data; D009154:Mutation
D017261:Glycosylphosphatidylinositols; D008565:Membrane Proteins; C080086:phosphatidylinositol glycan-class A protein