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Published on: November 16, 2011
Evolutionary expression of glucose-dependent-insulinotropic polypeptide (GIP)
Michelle C Musson1, Lisa I Jepeal, John R Finnerty
1Section of Gastroenterology, Boston University School of Medicine and Boston Medical Center, Boston, MA 02118, United States.
Regulatory Peptides
|July 5, 2011
Summary
Glucose-dependent insulinotropic polypeptide (GIP) evolved alongside insulin to enhance nutrient absorption and energy storage. Their roles varied across species, suggesting an adaptive evolutionary path for nutrient efficiency.
Area of Science:
- Comparative physiology
- Evolutionary biology
- Endocrinology
Background:
- Glucose-dependent insulinotropic polypeptide (GIP) is a key mammalian incretin hormone.
- Understanding GIP's evolutionary role alongside insulin is crucial for nutrient efficiency.
- Vertebrate models with varying pancreatic structures offer insights into GIP evolution.
Purpose of the Study:
- To investigate the functional evolution of GIP and its relationship with insulin.
- To delineate their respective roles in promoting nutrient efficiency across diverse species.
- To explore the evolutionary origins of GIP from ancestral genes.
Main Methods:
- Examined GIP and insulin expression patterns in sea lamprey, zebrafish, Xenopus laevis, chicken, and mouse.
- Utilized genomic analysis to predict potential GIP-like genes.
- Performed phylogenetic analysis of glucagon-like ligands.
Main Results:
- Sea lamprey lacked detectable GIP transcripts, with insulin confined to the pancreatic bud.
- GIP was found in both intestine and pancreas of zebrafish and X. laevis.
- Chicken and mouse showed GIP restricted to the intestine and insulin to the pancreas.
- Phylogenetic analysis supports GIP arising from proglucagon gene duplication.
Conclusions:
- The sea lamprey's intestinal insulin may negate the need for an enteroinsular axis.
- Zebrafish may represent an evolutionary stage where GIP is not yet an incretin.
- GIP and insulin likely confer survival advantages by improving nutrient absorption and energy storage efficiency.
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