RESUMO
An enhancer with amalgamated E-box and GATA motifs (+9.5) controls expression of the regulator of hematopoiesis GATA-2. While similar GATA-2-occupied elements are common in the genome, occupancy does not predict function, and GATA-2-dependent genetic networks are incompletely defined. A "+9.5-like" element resides in an intron of Samd14 (Samd14-Enh) encoding a sterile alpha motif (SAM) domain protein. Deletion of Samd14-Enh in mice strongly decreased Samd14 expression in bone marrow and spleen. Although steady-state hematopoiesis was normal, Samd14-Enh-/- mice died in response to severe anemia. Samd14-Enh stimulated stem cell factor/c-Kit signaling, which promotes erythrocyte regeneration. Anemia activated Samd14-Enh by inducing enhancer components and enhancer chromatin accessibility. Thus, a GATA-2/anemia-regulated enhancer controls expression of an SAM domain protein that confers survival in anemia. We propose that Samd14-Enh and an ensemble of anemia-responsive enhancers are essential for erythrocyte regeneration in stress erythropoiesis, a vital process in pathologies, including ß-thalassemia, myelodysplastic syndrome, and viral infection.
Assuntos
Anemia/metabolismo , Elementos Facilitadores Genéticos , Eritrócitos/metabolismo , Eritropoese , Fatores de Transcrição GATA/metabolismo , Proteínas/genética , Motivos de Aminoácidos , Animais , Proliferação de Células , Sobrevivência Celular , Eritrócitos/citologia , Fatores de Transcrição GATA/genética , Camundongos , Proteínas/metabolismo , Ativação TranscricionalRESUMO
Thousands of cis-elements in genomes are predicted to have vital functions. Although conservation, activity in surrogate assays, polymorphisms, and disease mutations provide functional clues, deletion from endogenous loci constitutes the gold-standard test. A GATA-2-binding, Gata2 intronic cis-element (+9.5) required for hematopoietic stem cell genesis in mice is mutated in a human immunodeficiency syndrome. Because +9.5 is the only cis-element known to mediate stem cell genesis, we devised a strategy to identify functionally comparable enhancers ("+9.5-like") genome-wide. Gene editing revealed +9.5-like activity to mediate GATA-2 occupancy, chromatin opening, and transcriptional activation. A +9.5-like element resided in Samd14, which encodes a protein of unknown function. Samd14 increased hematopoietic progenitor levels/activity and promoted signaling by a pathway vital for hematopoietic stem/progenitor cell regulation (stem cell factor/c-Kit), and c-Kit rescued Samd14 loss-of-function phenotypes. Thus, the hematopoietic stem/progenitor cell cistrome revealed a mediator of a signaling pathway that has broad importance for stem/progenitor cell biology.