Resistance to apoptosis caused by PIG-A gene mutations in paroxysmal nocturnal hemoglobinuria
AUTOR(ES)
Brodsky, Robert A.
FONTE
The National Academy of Sciences of the USA
RESUMO
Paroxysmal nocturnal hemoglobinuria (PNH) is a clonal hematopoietic stem cell disorder resulting from mutations in an X-linked gene, PIG-A, that encodes an enzyme required for the first step in the biosynthesis of glycosylphosphatidylinositol (GPI) anchors. PIG-A mutations result in absent or decreased cell surface expression of all GPI-anchored proteins. Although many of the clinical manifestations (e.g., hemolytic anemia) of the disease can be explained by a deficiency of GPI-anchored complement regulatory proteins such as CD59 and CD55, it is unclear why the PNH clone dominates hematopoiesis and why it is prone to evolve into acute leukemia. We found that PIG-A mutations confer a survival advantage by making cells relatively resistant to apoptotic death. When placed in serum-free medium, granulocytes and affected CD34+ (CD59−) cells from PNH patients survived longer than their normal counterparts. PNH cells were also relatively resistant to apoptosis induced by ionizing irradiation. Replacement of the normal PIG-A gene in PNH cell lines reversed the cellular resistance to apoptosis. Inhibited apoptosis resulting from PIG-A mutations appears to be the principle mechanism by which PNH cells maintain a growth advantage over normal progenitors and could play a role in the propensity of this disease to transform into more aggressive hematologic disorders. These data also suggest that GPI anchors are important in regulating apoptosis.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=23114Documentos Relacionados
- Paroxysmal nocturnal haemoglobinuria (PNH) is caused by somatic mutations in the PIG-A gene.
- Detection of somatic mutations of the PIG-A gene in Brazilian patients with paroxysmal nocturnal hemoglobinuria
- Genetic and environmental effects in paroxysmal nocturnal hemoglobinuria: this little PIG-A goes “Why? Why? Why?”
- A knock-out model of paroxysmal nocturnal hemoglobinuria: Pig-a(-) hematopoiesis is reconstituted following intercellular transfer of GPI-anchored proteins.
- Impaired growth and elevated Fas receptor expression in PIGA+ stem cells in primary paroxysmal nocturnal hemoglobinuria