Open Access
Transcription of the Human β Enolase Gene (ENO-3) Is Regulated by an Intronic Muscle-Specific Enhancer That Binds Myocyte-Specific Enhancer Factor 2 Proteins and Ubiquitous G-Rich-Box Binding Factors
Author(s) -
Salvatore Feo,
Vincenzo Antona,
Giovanna Barbieri,
Rosa Passantino,
Larissa Calı̀,
Agata Giallongo
Publication year - 1995
Publication title -
molecular and cellular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.14
H-Index - 327
eISSN - 1067-8824
pISSN - 0270-7306
DOI - 10.1128/mcb.15.11.5991
Subject(s) - biology , enhancer , microbiology and biotechnology , enhancer rnas , myod , chloramphenicol acetyltransferase , mef2 , transcription factor , e box , caat box , reporter gene , regulatory sequence , promoter , gene , enhancer trap , gene expression , genetics
To provide evidence for the cis-regulatory DNA sequences and trans-acting factors involved in the complex pattern of tissue- and stage-specific expression of the beta enolase gene, constructs containing fragments of the gene fused to the chloramphenicol acetyltransferase gene were used in transient-transfection assays of C2C12 myogenic cells. Deletion analysis revealed the presence of four major regions: two negative regions in the 5'-flanking sequence, a basal promoter region which directs expression at low levels in proliferating and differentiated muscle cells, and a positive region within the first intron that confers cell-type-specific and differentiation-induced expression. This positive regulatory element is located in the 3'-proximal portion of the first intron (nucleotides +504 to +637) and acts as an enhancer irrespective of orientation and position from the homologous beta enolase promoter or the heterologous thymidine kinase promoter, conferring in both cases muscle-specific expression to the linked reporter gene. Deletion of a putative myocyte-specific enhancer factor 1 (MEF-1) binding site, containing a canonical E-box motif, had no effects on muscle-specific transcription, indicating that this site is not required for the activity of the enhancer. Gel mobility shift assays, competition analysis, DNase I footprinting, and mutagenesis studies indicated that this element interacts through an A/T-rich box with a MEF-2 protein(s) and through a G-rich box with a novel ubiquitous factor(s). Mutation of either the G-rich box or the A/T-rich box resulted in a significantly reduced activity of the enhancer in transient-transfection assays. These data indicate that MEF-2 and G-rich-box binding factors are each necessary for tissue-specific expression of the beta enolase gene in skeletal muscle cells.