Trout and chicken proglucagon: alternative splicing generates mRNA transcripts encoding glucagon-like peptide 2

Area of Science:

• * Molecular Biology
• * Endocrinology
• * Evolutionary Biology

Background:

• * The proglucagon gene in mammals produces glucagon and two glucagon-like peptides (GLP 1 and GLP 2) via tissue-specific processing.
• * Previous studies indicated that bird and fish proglucagon genes encode only GLP 1, not GLP 2.

Purpose of the Study:

• * To investigate the presence of GLP 2 in the proglucagon gene of fish and birds.
• * To understand the regulation of proglucagon gene expression in different tissues of these species.

Main Methods:

• * Isolation and sequencing of intestinal proglucagon cDNAs from rainbow trout (Oncorhynchus mykiss) and chicken (Gallus gallus).
• * Analysis of mRNA splicing patterns in pancreatic and intestinal tissues.

Main Results:

• * The proglucagon gene in fish and birds contains sequences for both GLP 1 and GLP 2.
• * Pancreatic and intestinal proglucagon mRNAs in fish and birds exhibit different 3' ends due to alternative mRNA splicing.
• * Intestinal mRNA is spliced to include GLP 2 encoding exons, while pancreatic mRNA terminates before the GLP 2 exon.

Conclusions:

• * Proglucagon gene expression is regulated by alternative mRNA splicing in fish and birds.
• * The findings highlight the evolutionary conservation and potential biological significance of GLP 2 across species.
• * This study reveals novel insights into the differential expression of proglucagon-derived peptides.