Submitted to: Genbank
Publication Type: Abstract Only
Publication Acceptance Date: September 15, 2005
Publication Date: September 28, 2005
Citation: Richards, M.P., Poch, S.M., McMurtry, J.P. 2005. Gallus gallus preproglucagon B (GCG) mRNA, complete cds, alternatively spliced [abstract]. GenBank Accession No. DQ185931.
The proglucagon gene in mammals produces a single identical mRNA transcript in all tissues where it is expressed. This transcript encodes glucagon and two glucagon-like peptide hormones (GLP-1 and GLP-2). Previously, two distinct proglucagon mRNA transcripts have been identified in chickens, one in pancreas that encodes glucagon and GLP-1 but not GLP-2, and another in intestine that encodes glucagon and both GLPs. It was suggested that tissue-specific expression of these two mRNAs was important to the selective production of glucagon, GLP-1 and GLP-2 by proteolytic processing of the prohormone. The objective of this work was to isolate and characterize proglucagon mRNA transcripts in chickens. A molecular cloning strategy involving primer-directed reverse transcription polymerase chain reaction (RT-PCR) and rapid amplification of 5’ and 3’ cDNA ends (5’ and 3’ RACE) was developed to sequence 1183 bp of a chicken pancreas-derived cDNA corresponding to the complete coding region and the 5'- and 3'-untranslated regions of a chicken proglucagon class B mRNA transcript. The chicken proglucagon class B mRNA codes for a 206 amino acid preproprotein that includes a signal peptide, glucagon, GLP-1 and GLP-2 comprised of 22, 29, 37 and 33 amino acids, respectively. Class B mRNA was distinguished by its larger open reading frame (compared to class A) that included coding sequence for GLP-2 due to alternate splicing of the 3’ end of the initial gene transcript. The potential use of an alternate first exon also generates two class B mRNA transcript variants that differ in the sequence located at their 5’ ends. Together, this sequence data confirms the existence and provides additional information about the structure and function of the proglucagon gene in chickens. Such data will be useful in studying the structure and expression of this gene, as well as, in further defining the function of glucagon and GLP hormones in poultry.