A combination of closely associated positive and negative cis-acting promoter elements regulates transcription of the skeletal alpha-actin gene.
AUTOR(ES)
Chow, K L
RESUMO
The chicken skeletal alpha-actin gene promoter region provides at least a 75-fold-greater transcriptional activity in muscle cells than in fibroblasts. The cis-acting sequences required for cell type-restricted expression within this 200-base-pair (bp) region were elucidated by chloramphenicol acetyltransferase assays of site-directed Bg/II linker-scanning mutations transiently transfected into primary cultures. Four positive cis-acting elements were identified and are required for efficient transcriptional activity in myogenic cells. These elements, conserved across vertebrate evolution, include the ATAAAA box (-24 bp), paired CCAAT-box-associated repeats (CBARs; at -83 bp and -127 bp), and the upstream T+A-rich regulatory sequence (at -176 bp). Basal transcriptional activity in fibroblasts was not as dependent on the upstream CBAR or regions of the upstream T+A-rich regulatory sequence. Transfection experiments provided evidence that positive regulatory factors required for alpha-actin expression in fibroblasts are limiting. In addition, negative cis-acting elements were detected and found closely associated with the G+C-rich sequences that surround the paired CBARs. Negative elements may have a role in restricting developmentally timed expression in myoblasts and appear to inhibit promoter activity in nonmyogenic cells. Cell type-specific expression of the skeletal alpha-actin gene promoter is regulated by combinatorial and possibly competitive interactions between multiple positive and negative cis-acting elements.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=360830Documentos Relacionados
- Phased cis-acting promoter elements interact at short distances to direct avian skeletal alpha-actin gene transcription.
- Activation of skeletal alpha-actin gene transcription: the cooperative formation of serum response factor-binding complexes over positive cis-acting promoter serum response elements displaces a negative-acting nuclear factor enriched in replicating myoblasts and nonmyogenic cells.
- Delimitation and characterization of cis-acting DNA sequences required for the regulated expression and transcriptional control of the chicken skeletal alpha-actin gene.
- Characterization of cis-acting elements regulating transcription from the promoter of a constitutively active rice actin gene.
- A common factor regulates skeletal and cardiac alpha-actin gene transcription in muscle.