Plasticity of vascular smooth muscle alpha-actin gene transcription. Characterization of multiple, single-, and double-strand specific DNA-binding proteins in myoblasts and fibroblasts.
Transcriptional activity of the mouse vascular smooth muscle (VSM) alpha-actin promoter was governed by both cell type and developmental stage-specific mechanisms. A purine-rich motif (PrM) located as -181 to -176 in the promoter was absolutely required for activation in mouse AKR-2B embryonic fibroblasts and partially contributed to activation in undifferentiated mouse BC3H1 myoblasts. Transcriptional enhancer factor 1 recognized the PrM and cooperated with other promoter-binding proteins to regulate serum growth factor-dependent transcription in both myoblasts and fibroblasts. Two distinct protein factors (VAC-ssBF1 and VAC-ssBF2) also were identified that bound sequence-specifically to single-stranded oligonucleotide probes that spanned both the PrM and a closely positioned negative regulatory element. VAC-ssBF1 and BF2 binding activity was detected in undifferentiated myoblasts, embryonic fibroblasts, and several smooth muscle tissues in the mouse and human. A myoblast-specific protein (VAC-RF1) also was detected that bound double-stranded probes containing a CArG-like sequence that previously was shown to impart strong, cell type specific repression. The binding activity of transcription enhancer factor 1, VAC-RF1, and VAC-ssBF1 was significantly diminished when confluent BC3H1 myoblasts differentiated into myocytes and expressed VSM alpha-actin mRNA after exposure to serum-free medium. The results indicated that cell type-specific control of the VSM alpha-actin gene promoter required the participation of multiple DNA-binding proteins, including two that were enriched in smooth muscle and had preferential affinity for single-stranded DNA.
Cogan
J G
JG
Biochemistry Program, Ohio State University, College of Medicine, Columbus 43210-1239, USA.
Sun
S
S
Stoflet
E S
ES
Schmidt
L J
LJ
Getz
M J
MJ
Strauch
A R
AR
D000199:Actins / Q000096:biosynthesis* / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D002454:Cell Differentiation; D002460:Cell Line; D015500:Chloramphenicol O-Acetyltransferase / Q000096:biosynthesis; D004268:DNA-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D004622:Embryo, Mammalian; D005347:Fibroblasts / Q000378:metabolism; D015870:Gene Expression; D051379:Mice; D008806:Mice, Inbred AKR; D008969:Molecular Sequence Data; D009132:Muscles / Q000166:cytology / Q000378:metabolism*; D009687:Nuclear Proteins / Q000302:isolation & purification / Q000378:metabolism; D015345:Oligonucleotide Probes; D011401:Promoter Regions, Genetic; D016385:TATA Box; D014158:Transcription, Genetic; D014162:Transfection
D000199:Actins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D015345:Oligonucleotide Probes; D015500:Chloramphenicol O-Acetyltransferase