Acute Myeloid Leukemia Research Today is a free monthly online journal that collates and summarizes the latest research about Acute Myeloid Leukemia, including details on aml, symptoms, treatment, information. | ||||||||
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Low Mpl receptor expression in a pedigree with familial platelet disorder with predisposition to acute myelogenous leukemia and a novel AML1 mutation.Heller PG, Glembotsky AC, Gandhi MJ, Cummings CL, Pirola CJ, Marta RF, Kornblihtt LI, Drachman JG, Molinas FC Division of Hematology, Instituto de Investigaciones Médicas Alfredo Lanari, University of Buenos Aires, Argentina. idimhematologia@hotmail.com <idimhematologia@hotmail.com> Germ-line heterozygous mutations in the hematopoietic transcription factor AML1 (RUNX1) have been identified in patients with familial platelet disorder with predisposition to acute myelogenous leukemia (FPD/AML), which is characterized by thrombocytopenia, abnormal platelet function, and propensity to myeloid malignancies. We identified a novel mutation in the AML1 gene in an FPD/AML pedigree characterized by a single nucleotide deletion that generates a frameshift and premature chain termination (Pro218fs-Ter225). Both wild-type and mutant transcripts were expressed in affected individuals by allele-specific reverse transcriptase-polymerase chain reaction (RT-PCR). Thrombopoietin (TPO) binds to the Mpl receptor and is the major regulator of megakaryopoiesis. To explore the mechanisms underlying thrombocytopenia, we studied the TPO/Mpl pathway in this newly identified pedigree. TPO levels were mildly to moderately elevated. On flow cytometry and immunoblotting, Mpl receptor expression was decreased and TPO-induced signaling was impaired. While no mutations were identified in the MPL gene by sequence analysis, low MPL mRNA levels were found, suggesting decreased gene expression. Of particular interest, several AML1-binding motifs are present in the MPL promoter, suggesting MPL is an AML1 target. In conclusion, we identified a C-terminal AML1 mutation that leads to a decrease in Mpl receptor expression, providing a potential explanation for thrombocytopenia in this FPD/AML pedigree. Published 3 June 2005 in Blood, 105(12): 4664-70.
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