PHI--a new brain-gut peptide

Area of Science:

• Neuroendocrinology
• Peptide research
• Molecular biology

Background:

• The C-terminal amide structure in porcine intestinal extracts led to the discovery of peptide HI (PHI-27).
• PHI exhibits structural homologies to vasoactive intestinal peptide (VIP) and growth hormone-releasing factor (GRF).
• PHI displays biological activities similar to VIP, including inhibition of VIP receptor binding and stimulation of cyclic AMP production.

Purpose of the Study:

• To characterize the newly discovered peptide HI (PHI).
• To investigate the biological activities and receptor interactions of PHI.
• To determine the relationship between PHI and VIP, including their synthesis and distribution.

Main Methods:

• Detection and isolation of PHI from porcine intestinal extracts.
• Comparative analysis of amino acid sequences of PHI across different species (porcine, human, bovine).
• Deduction of amino acid sequence from cDNA sequence of VIP precursor in human neuroblastoma cells.

Main Results:

• PHI is a 27-amino acid peptide with structural similarities to VIP and GRF.
• PHI inhibits VIP binding to its receptors and stimulates cyclic AMP production.
• PHI is found in high concentrations in the brain and gut, suggesting a neurotransmitter/neuromodulator role.
• Human and bovine PHI sequences show minor variations compared to porcine PHI.
• Human PHI sequence is identical to a sequence within the VIP precursor, indicating co-synthesis.

Conclusions:

• Peptide HI (PHI) is a biologically active peptide with VIP-like functions.
• PHI likely functions as a neurotransmitter or neuromodulator in the central nervous system and gastrointestinal tract.
• PHI and VIP are co-synthesized from the same precursor molecule, highlighting a coordinated regulatory mechanism.