title: Distinct roles for SCL in erythroid specification and maturation in zebrafish.
abstract: The stem cell leukemia (SCL) transcription factor is essential for vertebrate hematopoiesis. Using the powerful zebrafish model for embryonic analysis, we compared the effects of either reducing or ablating Scl using morpholino-modified antisense RNAs. Ablation of Scl resulted in the loss of primitive and definitive hematopoiesis, consistent with its essential role in these processes. Interestingly, in embryos with severely reduced Scl levels, erythroid progenitors expressing gata1 and embryonic globin developed. Erythroid maturation was deficient in these Scl hypomorphs, supporting that Scl was required both for the erythroid specification and for the maturation steps, with maturation requiring higher Scl levels than specification. Although all hematopoietic functions were rescued by wild-type Scl mRNA, an Scl DNA binding mutant rescued primitive and definitive hematopoiesis but did not rescue primitive erythroid maturation. Together, we showed that there is a distinct Scl hypomorphic phenotype and demonstrated that distinct functions are required for the roles of Scl in the specification and differentiation of primitive and definitive hematopoietic lineages. Our results revealed that Scl participates in multiple processes requiring different levels and functions. Further, we identified an Scl hypomorphic phenotype distinct from the null state.
authors.affiliation: Department of Internal Medicine, Division of Hematology-Oncology and Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: Marianne A
authors.initials: MA
authors.lastname: Juarez
authors.forename: Fengyun
authors.initials: F
authors.lastname: Su
authors.forename: Sang
authors.initials: S
authors.lastname: Chun
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Kiel
authors.forename: Susan E
authors.initials: SE
authors.lastname: Lyons
mesh_terms: D017398:Alternative Splicing; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism / Q000502:physiology*; D002454:Cell Differentiation; D019070:Cell Lineage; D004247:DNA / Q000737:chemistry; D004268:DNA-Binding Proteins; D004587:Electrophoresis, Agar Gel; D050981:Erythroid-Specific DNA-Binding Factors / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D006410:Hematopoiesis; D017403:In Situ Hybridization; D008957:Models, Genetic; D009154:Mutation; D010641:Phenotype; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins / Q000378:metabolism / Q000502:physiology*; D012313:RNA / Q000737:chemistry; D016372:RNA, Antisense / Q000737:chemistry; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013234:Stem Cells; D000073942:T-Cell Acute Lymphocytic Leukemia Protein 1; D014157:Transcription Factors; D015027:Zebrafish; D029961:Zebrafish Proteins / Q000378:metabolism / Q000502:physiology*
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D004247:DNA; D004268:DNA-Binding Proteins; D050981:Erythroid-Specific DNA-Binding Factors; D011518:Proto-Oncogene Proteins; D012313:RNA; D016372:RNA, Antisense; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D000073942:T-Cell Acute Lymphocytic Leukemia Protein 1; D014157:Transcription Factors; D029961:Zebrafish Proteins; C489367:tal1 protein, zebrafish