Konference: 2006 48th ASH Annual Meeting - účast ČR
Maligní lymfomy a leukémie
Téma: Publikace ve sborníku
Číslo abstraktu: 4207
Autoři: Mgr. Vít Pospíšil; Prof. MUDr. Emanuel Nečas, DrSc.; Doc. MUDr. Tomáš Stopka, Ph.D.
Myeloid cell commitment is regulated by factors interacting with
chromatin in a progenitor cell entering differentiation. PU.1 is an
ETS family transcription factor that has been well characterized in
inducing myelopoiesis and blocking erythroid differentiation.
Conditionally activated PU.1-Estrogen Receptor transgene in mouse
PU.1 knockout-derived hematopoietic progenitors is known to induce
macrophage differentiation. We observed that manipulation of PU.1
activity by using different levels of PU.1-ER activator, tamoxifen,
was capable of producing major populations of myeloid progeny
including macrophages, granulocytes, lymphocytes and mastocytes.
Gradual activation of PU.1 produce distinct committed populations
that require presence of PU.1 activator. Withdrawal of tamoxifen
from macrophages restored cycling and pluripotent potential
resembling parental cell line. Furthermore, very low PU.1 activity
induced frequent chromosomal aberations such as polyploidy. To
determine that PU.1 directly caused these phenotypic changes we
determined its occupancy at genes representing PU.1 targets by
quantitative chromatin immunoprecipitation (ChIP). We demonstrate
that PU.1 is enriched at regulatory regions of lineage restricted
cell populations including promoters of CD11b, CD14, IL7R, PAX5,
RAG1, Gelatinase, Lysozyme, and MCP. Different PU.1 levels promote
distinct cell populations that have different localizations of PU.1
in chromatin. We also tested mRNA levels of PU.1 target genes in
progenitor cell line induced by PU.1. Macrophage-specific target
genes such as CD11b and CD14 are induced at high PU.1 levels and
granulocytic PU.1 targets such as Gelatinase and Lysozyme are
induced at intermediate and high PU.1 levels. B-cell specific mRNAs
such as IL7-R, PAX5, and RAG1 were induced at low and high PU.1
levels. Our data suggest that PU.1 is recruited to and
transactivates its lineage-restricted target genes differently at
distinct PU.1 levels and such mechanism may be involved in myeloid
cell commitment and leukemogenesis.
(Support: NR/9021-4, 301/06/1093, 0021620813, 2B06077).
Datum přednesení příspěvku: 9. 12. 2006