title: Lhx2 expression promotes self-renewal of a distinct multipotential hematopoietic progenitor cell in embryonic stem cell-derived embryoid bodies.
abstract: The molecular mechanisms regulating the expansion of the hematopoietic system including hematopoietic stem cells (HSCs) in the fetal liver during embryonic development are largely unknown. The LIM-homeobox gene Lhx2 is a candidate regulator of fetal hematopoiesis since it is expressed in the fetal liver and Lhx2(-/-) mice die in utero due to severe anemia. Moreover, expression of Lhx2 in embryonic stem (ES) cell-derived embryoid bodies (EBs) can lead to the generation of HSC-like cell lines. To further define the role of this transcription factor in hematopoietic regulation, we generated ES cell lines that enabled tet-inducible expression of Lhx2. Using this approach we observed that Lhx2 expression synergises with specific signalling pathways, resulting in increased frequency of colony forming cells in developing EB cells. The increase in growth factor-responsive progenitor cells directly correlates to the efficiency in generating HSC-like cell lines, suggesting that Lhx2 expression induce self-renewal of a distinct multipotential hematopoietic progenitor cell in EBs. Signalling via the c-kit tyrosine kinase receptor and the gp130 signal transducer by IL-6 is necessary and sufficient for the Lhx2 induced self-renewal. While inducing self-renewal of multipotential progenitor cells, expression of Lhx2 inhibited proliferation of primitive erythroid precursor cells and interfered with early ES cell commitment, indicating striking lineage specificity of this effect.
authors.affiliation: Umeå Center for Molecular Medicine, Umeå University, Umeå, Sweden.
authors.forename: Lina
authors.initials: L
authors.lastname: Dahl
authors.forename: Karin
authors.initials: K
authors.lastname: Richter
authors.forename: Anna-Carin
authors.initials: AC
authors.lastname: Hägglund
authors.forename: Leif
authors.initials: L
authors.lastname: Carlsson
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D002999:Clone Cells; D003114:Colony-Forming Units Assay; D004318:Doxycycline / Q000494:pharmacology; D053595:Embryonic Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D041905:Erythroid Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D018398:Homeodomain Proteins / Q000378:metabolism*; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000494:pharmacology; D015850:Interleukin-6 / Q000494:pharmacology; D060850:LIM-Homeodomain Proteins; D051379:Mice; D008954:Models, Biological; D039902:Multipotent Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D019089:Stem Cell Factor / Q000494:pharmacology; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D018398:Homeodomain Proteins; D036341:Intercellular Signaling Peptides and Proteins; D015850:Interleukin-6; D060850:LIM-Homeodomain Proteins; C489784:Lhx2 protein, mouse; D019089:Stem Cell Factor; D014157:Transcription Factors; D004318:Doxycycline