The compound β°-thalassemia/Hb E hemoglobinopathy is characterized by an unusually
large range of presentation from essentially asymptomatic to a severe transfusion dependent
state. While a number of factors are known that moderate presentation, these factors
do not account for the full spectrum of presentation. Mitochondria are subcellular organelles
that are pivotal in a number of cellular processes including oxidative phosphorylation and
apoptosis. A mitochondrial protein enriched proteome was determined and validated from
erythroblasts from normal controls and β°-thalassemia/Hb E patients of different severities.
Mitochondria were evaluated through the use of mitotracker staining, analysis of relative
mitochondrial genome number and evaluation of mitochondrial gene expression in addition
to assay of overall cellular redox status through the use of alamarBlue assays. Fifty differentially
regulated mitochondrial proteins were identified. Mitotracker staining revealed
significant differences in staining between normal control erythroblasts and those from
β°-thalassemia/Hb E patients. Differences in relative mitochondria number and gene
expression were seen primarily in day 10 cells. Significant differences were seen in redox
status as evaluated by alamarBlue staining in newly isolated CD34+ cells. Mitochondria
mediate oxidative phosphorylation and apoptosis, both of which are known to be dysregulated
in differentiating erythrocytes from β°-thalassemia/Hb E patients. The evidence presented
here suggest that there are inherent differences in these cells as early as the
erythroid progenitor cell stage, and that maximum deficit is seen coincident with high levels
of globin gene expression.
Introduction