Endogenous peptide diversity, GLP-1 drugs, and methods for novel peptide discovery.
TOPICS DISCUSSED:
Peptide Structure & Production: Short amino acid chains (3-50 residues) cleaved from larger precursors by PCSK enzymes, stored in dense-core vesicles, and released upon stimuli rather than acting as folded enzymes like proteins.
Tissue-Specific Processing: The same precursor yields different peptides by tissue; preproglucagon produces glucagon in pancreas but GLP-1 in gut L-cells due to distinct cleavage patterns.
Signaling Timescales: Peptides act over minutes via GPCRs and can drive longer transcriptional changes such as FOS expression, yet are cleared rapidly by proteases and kidneys.
Endogenous GLP-1: Meal-stimulated incretin from gut that boosts insulin secretion with a half-life of only minutes, limiting primary action to periphery rather than deep brain structures.
GLP-1 Engineering for Brain Access: DPP4 site mutations plus lipid conjugation enable albumin binding, extend half-life, and raise brain exposure.
Dose-Dependent Effects: Low GLP-1 doses mainly lower blood glucose via pancreas; higher doses engage hindbrain and hypothalamic neurons to suppress appetite and alter food preference.
Novel Peptide Discovery: Computational scans across the genome flag hundreds of uncharacterized precursors, facilitating new peptide discovery.
BRP Peptide: This newly discovered brain-derived peptide suppresses feeding in GLP-1 receptor knockout mice, activates non-overlapping neurons, and does not slow gastric emptying.
ABOUT THE GUEST: Katrin Svensson, PhD, is a biochemist and physiologist who leads a laboratory at Stanford University focused on peptide hormone physiology and the regulation of energy balance.
PRACTICAL TAKEAWAYS:
GLP-1 drugs require higher doses to engage brain satiety circuits for meaningful weight loss; lower doses primarily improve glucose control with little effect on appetite.
Response varies widely across individuals, with some losing over 25% body weight while others see minimal change.
Emerging peptides under study may suppress appetite via brain pathways that avoid the gastric slowing responsible for common GI side effects of current GLP-1 drugs.
Research peptides purchased online frequently show variable purity below pharmaceutical standards and may contain unsafe formulation components or aggregates.
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