title: Sca-1 is an early-response target of histone deacetylase inhibitors and marks hematopoietic cells with enhanced function.
abstract: Histone deacetylase inhibitors (HDIs) have been shown to enhance hematopoietic stem and progenitor cell activity and improve stem cell outcomes after ex vivo culture. Identification of gene targets of HDIs is required to understand the full potential of these compounds and can allow for improved stem cell culturing protocols. The molecular process that underlies the biological effects of valproic acid (VPA), a widely used HDI, on hematopoietic stem/progenitor cells was investigated by studying the early-response genes of VPA. These genes were linked to VPA-induced enhancement of cell function as measured by in vitro assays. Genome-wide gene expression studies revealed over-representation of genes involved in glutathione metabolism, receptor and signal transducer activity, and changes in the hematopoietic stem/progenitor cells surface profile after short, 24-hour VPA treatment. Sca-1, a well-known and widely used stem cell surface marker, was identified as a prominent VPA target. We showed that multiple HDIs induce Sca-1 expression on hematopoietic cells. VPA strongly preserved Sca-1 expression on Lin(-)Sca1(+)ckit(+) cells, but also reactivated Sca-1 on committed progenitor cells that were Sca-1(neg), thereby reverting them to the Lin(-)Sca1(+)ckit(+) phenotype. We demonstrated that reacquired Sca-1 expression coincided with induced self-renewal capacity as measured by in vitro replating assays, while Sca-1 itself was not required for the biological effects of VPA as demonstrated using Sca-1-deficient progenitor cells. In conclusion, our results show that VPA modulates several genes involved in multiple signal transduction pathways, of which Sca-1 was shown to mark cells with increased self-renewal capacity in response to HDIs.
authors.affiliation: Department of Biology of Aging, Section Stem Cell Biology, European Research Institute for the Biology of Aging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
authors.forename: Marta A
authors.initials: MA
authors.lastname: Walasek
authors.forename: Leonid V
authors.initials: LV
authors.lastname: Bystrykh
authors.forename: Sandra
authors.initials: S
authors.lastname: Olthof
authors.forename: Gerald
authors.initials: G
authors.lastname: de Haan
authors.forename: Ronald
authors.initials: R
authors.lastname: van Os
mesh_terms: D000818:Animals; D000950:Antigens, Ly / Q000502:physiology*; D002454:Cell Differentiation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005260:Female; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000187:drug effects*; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology*; D008565:Membrane Proteins / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D014635:Valproic Acid / Q000494:pharmacology*
chemical_list: D000950:Antigens, Ly; D056572:Histone Deacetylase Inhibitors; C074650:Ly6a protein, mouse; D008565:Membrane Proteins; D014635:Valproic Acid