UCLA

Diamond-Blackfan Anemia (DBA) is a genetic bone marrow failure syndrome, typically diagnosed in infants within the first year of life. It is characterized by macrocytic anemia, congenital abnormalities affecting the head, limbs, heart, and genitourinary system, and higher incidence of cancer, including leukemia and solid tumors. DBA is associated with mutations in ribosomal proteins, most commonly RPS19, and several groups have shown p53 pathway upregulation to play a significant role in DBA pathogenesis, though the overall mechanism of disease development remains unclear. Current treatments for DBA include corticosteroids, which have multiple side-effects in children, including short stature and delayed growth; blood transfusions, which carry a risk of organ failure from iron overload; and bone marrow transplants, which require immunosuppression and can result in mortality. Given the undesirable side effects of current DBA treatments, and the tumor suppressor function of p53, which makes it a poor target for therapy, more research is needed to uncover pathways involved in DBA pathogenesis and to identify new drug targets that may be useful for treating DBA.

In this dissertation, we used primary human hematopoietic progenitor cells from fetal liver and cord blood that were transduced with lentivirus carrying shRNA against RPS19 as a model to identify novel pathways that play a role in DBA. In Chapter 2, we show that RPS19 deficient cells have reduced expression of the erythroid transcription factor GATA1, and that this reduction is p53-dependent and mediated by the inflammatory cytokine TNF-α. In Chapter 3, we describe the use of next-generation RNA sequencing to identify pathways dysregulated in RPS19 deficient cells, including inflammation mediated by chemokine and cytokine signaling, WNT signaling pathway, TGF-β signaling pathway, and the transcription factor c-MYC. Finally, in Chapter 4, we explore the role of microRNAs in DBA pathogenesis identified by next-generation microRNA-sequencing, and describe the role of the microRNA miR-34a in RPS19 deficient cells and in erythropoiesis. Taken together, our results suggest a novel role for inflammatory pathways in the pathogenesis of DBA, which can potentially be targeted to develop new treatments for this disease.