Cloning and transcriptional analysis of the mouse receptor activity modifying protein-1 gene promoter.
BACKGROUND
Receptor activity modifying protein-1 (RAMP-1) is a single transmembrane-domain protein required for the functional expression of calcitonin gene-related peptide (CGRP) receptors. To date, little is known about the molecular mechanism(s) that activate/inhibit RAMP-1 gene expression. Such mechanism(s) are likely to play a major role in modulating the responsiveness of tissues to CGRP.


RESULTS
To initiate studies on the transcriptional regulation of the mouse RAMP-1 gene, RAMP-1 transcriptional initiation sites were mapped in a variety of tissues. Analysis of RAMP-1 expression in C2C12 myoblasts demonstrated that RAMP-1 mRNA is expressed at greatest levels in confluent myoblasts verses non-confluent and fused myoblasts. Transfection of confluent C2C12 myoblasts and NIH 3T3 cells with RAMP-1 promoter/luciferase deletion constructs revealed that 4.7 kb of RAMP-1 5' flanking region demonstrated optimal promoter activity while 343 bp of 5' flanking region was defined as a minimal RAMP-1 promoter. In non-RAMP-1 expressing HEK293 cells, constructs containing 4.7 kb to 782 bp of RAMP-1 5' flanking region were transcriptionally inactive. However, deletion of sequences -782 to -343 activated RAMP-1 promoter activity.


CONCLUSIONS
These findings suggest that tissue specificity of RAMP-1 gene expression is mediated by a negative acting transcription factor that represses RAMP-1 gene expression in non-RAMP-1 expressing tissues. This transcription factor is therefore likely to play an important role in modulating the responsiveness of tissues to CGRP.
Pondel
Marc D
MD
Department of Cellular and Molecular Medicine, St. George's Hospital Medical School, Cranmer Terrace, London, SW17 ORE, UK. mpondel@sghms.ac.uk
Mould
Richard
R
D024506:5' Flanking Region / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D045744:Cell Line, Tumor / Q000378:metabolism; D003001:Cloning, Molecular; D005786:Gene Expression Regulation; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics*; D008565:Membrane Proteins / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D018485:Muscle Fibers, Skeletal / Q000378:metabolism; D032446:Myoblasts / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics*; D058261:Receptor Activity-Modifying Proteins; D012097:Repressor Proteins / Q000378:metabolism; D017422:Sequence Analysis, DNA; D024363:Transcription Initiation Site; D014162:Transfection
D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D058261:Receptor Activity-Modifying Proteins; D012097:Repressor Proteins