Microarray transfection analysis of conserved genomic sequences from three immediate early genes

A novel fluorescent transcriptional reporter for cell-based microarray assays

Cell-based microarrays have been used for a wide variety of assays including gain-of-function, loss-of-function and compound screening. Many of these assays have employed fluorescent proteins as reporters. These fluorescent reporter proteins can be monitored in living cells but have low sensitivity of detection compared to enzymatic reporters. Here we have described a novel transcriptional reporter assay using the alkaline phosphatase reporter enzyme and a fluorescent substrate (ELF-97) to screen for gain-of-function mutations in the type-I cGMP-dependent protein kinase (PRKG1). We have identified a constitutively active mutant of this enzyme in which a conserved Glu at position 81 was mutated to Lys.

A novel mouse c-fos intronic promoter that responds to CREB and AP-1 is developmentally regulated in vivo

Background

The c-fos proto-oncogene is an archetype for rapid and integrative transcriptional activation. Innumerable studies have focused on the canonical promoter, located upstream from the transcriptional start site. However, several regulatory sequences have been found in the first intron.

Methodology/Principal Findings

Here we describe an extremely conserved region in c-fos first intron that contains a putative TATA box, and functional TRE and CRE sites. This fragment drives reporter gene activation in fibroblasts, which is enhanced by increasing intracellular calcium and cAMP and by cotransfection of CREB or c-Fos/c-Jun expression vectors. We produced transgenic mice expressing a lacZ reporter controlled by the intronic promoter. Lac Z expression of this promoter is restricted to the developing central nervous system (CNS) and the mesenchyme of developing mammary buds in embryos 12.5 days post-conception, and to brain tissue in adults. RT-QPCR analysis of tissue mRNA, including the anlage of the mammary gland and the CNS, confirms the existence of a novel, nested mRNA initiated in the first intron.

Conclusions/Significance

Our results provide evidence for a novel, developmentally regulated promoter in the first intron of the c-fos gene.