Serum response factor utilizes distinct promoter- and enhancer-based mechanisms to regulate cytoskeletal gene expression in macrophages.
Cells of the monocyte/macrophage lineage play essential roles in tissue homeostasis and immune responses, but mechanisms underlying the coordinated expression of cytoskeletal genes required for specialized functions of these cells, such as directed migration and phagocytosis, remain unknown. Here, using genetic and genomic approaches, we provide evidence that serum response factor (SRF) regulates both general and cell type-restricted components of the cytoskeletal gene expression program in macrophages. Genome-wide location analysis of SRF in macrophages demonstrates enrichment of SRF binding at ubiquitously expressed target gene promoters, as expected, but also reveals that the majority of SRF binding sites associated with cell type-restricted target genes are at distal inter- and intragenic locations. Most of these distal SRF binding sites are established by the prior binding of the macrophage- and the B cell-specific transcription factor PU.1 and exhibit histone modifications characteristic of enhancers. Consistent with this, representative cytoskeletal target genes associated with these elements require both SRF and PU.1 for full expression. These findings suggest that SRF uses two distinct molecular strategies to regulate programs of cytoskeletal gene expression: a promoter-based strategy for ubiquitously expressed target genes and an enhancer-based strategy at target genes that exhibit cell type-restricted patterns of expression.
University of California, San Diego, Department of Cellular and Molecular Medicine, La Jolla, CA 92093-0651, USA.
Amy L
AL
Sullivan
Christopher
C
Benner
Sven
S
Heinz
Wendy
W
Huang
Lan
L
Xie
Joseph M
JM
Miano
Christopher K
CK
Glass
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000235:genetics* / Q000378:metabolism*; D017931:DNA Primers / Q000235:genetics; D004742:Enhancer Elements, Genetic; D006410:Hematopoiesis / Q000235:genetics / Q000502:physiology; D008264:Macrophages / Q000166:cytology / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D011401:Promoter Regions, Genetic; D011518:Proto-Oncogene Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D026362:Serum Response Factor / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism*; D015534:Trans-Activators / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation; D000099232:Proto-Oncogene Protein Spi-1
D017931:DNA Primers; D011518:Proto-Oncogene Proteins; D034741:RNA, Small Interfering; D026362:Serum Response Factor; D015534:Trans-Activators; D000099232:Proto-Oncogene Protein Spi-1