Intragenic Sequences Affect the Expression of the Gene Encoding Glial Fibrillary Acidic Protein

We show that the expression of the gene encoding glial fibrillary acidic protein (GFAP) gene is affected by at least three cis-acting elements. A positive regulatory element that is located between nucleotides -1,631 and -1,479 can confer cell type-specific expression on a heterologous gene. A second regulatory element is located between nucleotides -97 and -80. The third is a negative regulatory element that is located within the first intron of the gene. Deletion of this element activates GFAP expression in HeLa cells, and affects promoter function in glioma cells.     

Vascular-specific expression of the bean GRP 1.8 gene is negatively regulated.

In French bean, the glycine-rich cell wall protein GRP 1.8 is specifically synthesized in the vascular tissue. To identify cis-acting sequences required for cell type-specific synthesis of GRP 1.8, expression patterns of fusion gene constructs were analyzed in transgenic tobacco. In these constructs, the uidA (beta-glucuronidase) gene was placed under control of 5' upstream deletions as well as internal deletions of the GRP 1.8 promoter. Four different cis-acting regulatory regions, SE1 and SE2 (stem elements), a negative regulatory element, and a root-specific element, were found to control the tissue-specific expression. Deletion of the negative regulatory element resulted in expression of the uidA gene in cell types other than vascular cells. The SE1 region was essential for expression in several cell types in the absence of further upstream regulatory sequences. Full-length promoters having insertions between the negative regulatory element and SE1 strongly expressed the gene in nonvascular cell types in stems and leaves. Thus, vascular-specific expression of the GRP 1.8 promoter is controlled by a complex set of positive and negative interactions between cis-acting regulatory regions. The disturbance of these interactions results in expression in additional cell types.     

Identification of negative and positive regulatory elements associated with a class I major histocompatibility complex gene.

Regulatory DNA sequence elements were functionally identified in the 5'-flanking region of a gene, PD1, which encodes a porcine classical transplantation antigen. Both a positive regulatory element and a novel negative regulatory DNA element were mapped within 1.1 kilobases upstream of exon 1. The negative regulatory element reduced the activity of both the homologous PD1 promoter and a heterologous simian virus 40 promoter. In vivo competition experiments indicated that the functions of the PD1 positive and negative regulatory elements are mediated by distinct cellular trans-acting factors. The PD1 positive regulatory element interacted with cellular factors in common with those binding to the simian virus 40 enhancer. Finally, the negative regulatory element required the presence of a positive regulatory element to function. This interaction between positive and negative regulatory elements represents a novel mechanism for regulating gene expression.