MDS and DNA repair defects in Crebbp+/- mice

Myelodysplastic syndrome (MDS) is considered a disease of hematopoietic stem cell (HSC) origin. To begin to unravel the molecular mechanisms underlying the deregulation of HSCs in MDS, we performed comparative gene expression profiling on Crebbp+/- and wild type HSCs. We chose to isolate HSCs from the fetal liver (FLHSC) because at this stage there were no differences in cell number between Crebbp+/- and wild type fetal livers, suggesting no overt hematopoietic differences. Thus, any change in gene expression found in Crebbp+/- FLHSCs is likely to reflect the initially compromised genetic program of HSC regulation, as opposed to that of Crebbp+/- HSCs in adult bone marrow, where secondary changes in gene expression may also occur as compensatory mechanisms for a compromised or failing hematopoietic system. We used day 14.5 post coitus FLHSC (Sca-1+,Lin-,AA4.1+,c-Kit++) from wild type (wt) and Crebbp heterozygous (ht) embryos to examine changes in gene expression before overt myelodysplastic disease manifestation. Total RNA from wt and Crebbp+/- FLHSCs was isolated, PCR-amplified using the Ovation RNA amplification system and hybridized to Affymetrix Mouse 430 2.0 expression microarrays.