• Hedgehog Signaling Regulates Friend of GATA to Maintain Hematopoietic Progenitor Cells in Drosophila Melanogaster

      Baldeosingh, Rajkumar; Fossett, Nancy; 0000-0002-8673-3285 (2016)
      Hematopoietic stem cells must be capable of both self-renewal and production of progenitor cells that give rise to all of the blood cell types, the two basic principles of stem cell biology. These unique stem cell properties have generated vast interest, due to the potential of stem cell therapies to treat various types of blood diseases. In this study, fly genetics were used to identify factors that act with the GATA:Friend Of GATA (GATA:FOG) complex to maintain hematopoietic progenitor cells. The Hedgehog signaling factor, Smoothened, was identified as one of those factors. We have determined that canonical Hedgehog signaling regulates U-shaped, the Drosophila homologue of FOG, to maintain hematopoietic progenitors. Furthermore, we propose a model in which we outline how Hedgehog signaling maintains FOG and hematopoietic progenitors. Our results may identify conserved regulatory mechanisms whereby signals from the microenvironment control progenitor differentiation.
    • Regulators of Hematopoietic Progenitor Differentiation

      Baldeosingh, Rajkumar; Gao, Hongjuan; Wu, Xiaorong; Fossett, Nancy (2015-03-09)
      Hematopoietic stem cells (HSCs) must be capable of both self-renewal and production of progenitor cells that give rise to all of the blood cell types, the two basic principles of stem cell biology. Investigations into gene networks controlling HSC response to stress have been conducted using model organisms such as Drosophila melanogaster. One of the factors controlling vertebrate HSC multipotency and differentiation is the GATA:FOG complex. GATA:FOG complexes regulate the development of a number of blood lineages. In Drosophila, the GATA:FOG complex blocks the differentiation of hematopoietic progenitors into the stress-responsive lamellocyte lineage. Drosophila hematopoietic progenitors are strikingly similar to HSCs and are used as a model for these vertebrate stem cells. We used fly genetics to identify GATA:FOG network members that block the stress-response of hematopoietic progenitors.