Plasticity of vascular smooth muscle alpha-actin gene transcription. Characterization of multiple, single-, and double-strand specific DNA- binding proteins in myoblasts and fibroblasts

• Published in: The Journal of biological chemistry Vol. 270; no. 19; pp. 11310 - 11321
• Main Authors: Cogan, J G, Sun, S, Stoflet, E S, Schmidt, L J, Getz, M J, Strauch, A R
• Format: Journal Article
• Language: English
• Published: United States American Society for Biochemistry and Molecular Biology 12-05-1995
• Subjects: Actins - biosynthesis; Actins - genetics; Animals; Base Sequence; Cell Differentiation; Cell Line; Chloramphenicol O-Acetyltransferase - biosynthesis; DNA-Binding Proteins - isolation & purification; DNA-Binding Proteins - metabolism; Embryo, Mammalian; Fibroblasts - metabolism; Gene Expression; Mice; Mice, Inbred AKR; Molecular Sequence Data; Muscles - cytology; Muscles - metabolism; Nuclear Proteins - isolation & purification; Nuclear Proteins - metabolism; Oligonucleotide Probes; Promoter Regions, Genetic; TATA Box; Transcription, Genetic; Transfection
• ISSN: 0021-9258; 1083-351X

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.