Co-stimulation of the bone-related Runx2 P1 promoter in mesenchymal cells by SP1 and ETS transcription factors at polymorphic purine-rich DNA sequences (Y-repeats).
Transcriptional control of Runx2 gene expression through two alternative promoters (P1 and P2) is critical for the execution of its function as an osteogenic cell fate determining factor. In all vertebrates examined to date, the bone related P1 promoter contains a purine-rich region (-303 to -128 bp in the rat) that separates two regulatory domains. The length of this region differs dramatically between species even within the same order. Using deletion analysis, we show that part of this purine-rich region (-200 to -128) containing a duplicated element (Y-repeat) positively regulates Runx2 P1 transcription. Electrophoretic mobility assays and chromatin immunoprecipitations reveal that Y-repeat binds at least two different classes of transcription factors related to GC box binding proteins (e.g. SP1 and SP7/Osterix) and ETS-like factors (e.g. ETS1 and ELK1). Forced expression of SP1 increases Runx2 P1 promoter activity through the Y-repeats, and small interfering RNA depletion of SP1 decreases Runx2 expression. Similarly, exogenous expression of wild type ELK1, but not a defective mutant that cannot be phosphorylated, enhances Runx2 gene expression. SP1 is most abundant in proliferating cells, and ELK1 is most abundant in postconfluent cells; during MC3T3-E1 osteoblast differentiation, both proteins are transiently co-expressed when Runx2 expression is enhanced. Taken together, our data suggest that basal Runx2 gene transcription is regulated by dynamic interactions between SP1 and ETS-like factors during progression of osteogenesis.
Zhang
Ying
Y
Department of Cell Biology and Cancer Center, University of Massachusetts Medical School, Worcester, Massachusetts 01655.
Hassan
Mohammad Q
MQ
Department of Cell Biology and Cancer Center, University of Massachusetts Medical School, Worcester, Massachusetts 01655.
Xie
Rong-Lin
RL
Department of Cell Biology and Cancer Center, University of Massachusetts Medical School, Worcester, Massachusetts 01655.
Hawse
John R
JR
Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905.
Spelsberg
Thomas C
TC
Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905.
Montecino
Martin
M
Departamento de Bioquimica y Biologia Molecular, Facultad de Ciencias Biologicas, Universidad de Concepcion, Concepcion, Chile.
Stein
Janet L
JL
Department of Cell Biology and Cancer Center, University of Massachusetts Medical School, Worcester, Massachusetts 01655.
Lian
Jane B
JB
Department of Cell Biology and Cancer Center, University of Massachusetts Medical School, Worcester, Massachusetts 01655.
van Wijnen
Andre J
AJ
Department of Cell Biology and Cancer Center, University of Massachusetts Medical School, Worcester, Massachusetts 01655.
Stein
Gary S
GS
Department of Cell Biology and Cancer Center, University of Massachusetts Medical School, Worcester, Massachusetts 01655. Electronic address: gary.stein@umassmed.edu.
D016475:3T3 Cells; D000818:Animals; D001483:Base Sequence; D002454:Cell Differentiation; D047369:Chromatin Immunoprecipitation; D050659:Core Binding Factor Alpha 1 Subunit / Q000235:genetics*; D017931:DNA Primers; D024202:Electrophoretic Mobility Shift Assay; D020869:Gene Expression Profiling; D055785:Gene Knockdown Techniques; D017930:Genes, Reporter; D008156:Luciferases / Q000235:genetics; D051379:Mice; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism*; D011110:Polymorphism, Genetic; D011401:Promoter Regions, Genetic; D050784:Proto-Oncogene Protein c-ets-1 / Q000235:genetics / Q000502:physiology*; D034622:RNA Interference; D012091:Repetitive Sequences, Nucleic Acid; D016329:Sp1 Transcription Factor / Q000235:genetics / Q000502:physiology*
D050659:Core Binding Factor Alpha 1 Subunit; D017931:DNA Primers; D050784:Proto-Oncogene Protein c-ets-1; C493716:Runx2 protein, mouse; D016329:Sp1 Transcription Factor; D008156:Luciferases