Short Report

The proximal first exon architecture of the murine ghrelin gene is highly similar to its human orthologue

Inge Seim, Shea L Carter, Adrian C Herington and Lisa K Chopin^*

• * Corresponding author: Lisa K Chopin l.chopin@qut.edu.au

Author Affiliations

Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, Queensland, Australia

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BMC Research Notes 2009, 2:85 doi:10.1186/1756-0500-2-85

Published: 9 May 2009

Abstract

Background

The murine ghrelin gene (Ghrl), originally sequenced from stomach tissue, contains five exons and a single transcription start site in a short, 19 bp first exon (exon 0). We recently isolated several novel first exons of the human ghrelin gene and found evidence of a complex transcriptional repertoire. In this report, we examined the 5' exons of the murine ghrelin orthologue in a range of tissues using 5' RACE.

Findings

5' RACE revealed two transcription start sites (TSSs) in exon 0 and four TSSs in intron 0, which correspond to 5' extensions of exon 1. Using quantitative, real-time RT-PCR (qRT-PCR), we demonstrated that extended exon 1 containing Ghrl transcripts are largely confined to the spleen, adrenal gland, stomach, and skin.

Conclusion

We demonstrate that multiple transcription start sites are present in exon 0 and an extended exon 1 of the murine ghrelin gene, similar to the proximal first exon organisation of its human orthologue. The identification of several transcription start sites in intron 0 of mouse ghrelin (resulting in an extension of exon 1) raises the possibility that developmental-, cell- and tissue-specific Ghrl mRNA species are created by employing alternative promoters and further studies of the murine ghrelin gene are warranted.