Summary
GLP-1 (glucagon-like peptide-1) is a hormone produced in the gut that plays a central role in regulating blood sugar, appetite, and digestion. It's the very hormone that blockbuster drugs like Ozempic and Wegovy are designed to mimic. But GLP-1 is not just triggered by medication — the body naturally releases it in response to food. This study investigated the precise molecular mechanisms by which meat-derived proteins and essential amino acids stimulate GLP-1 release from gut cells, and what internal signaling pathways are responsible.
Researchers used a well-established human gut cell model called the NCI-H716 cell line — cells that behave like the specialized intestinal cells (called L-cells) that produce and secrete GLP-1. They exposed these cells to meat hydrolysate (a solution of partially digested meat proteins, similar to what reaches the gut after eating) and individual essential amino acids, then used chemical inhibitors to identify exactly which internal cellular signaling pathways were responsible for triggering GLP-1 release.
What they found:
- Both meat hydrolysate and essential amino acids were powerful stimulators of GLP-1 secretion from gut cells.
- The GLP-1 release was driven primarily through two key cellular signaling pathways: ERK1/2 and p38 MAPK — both members of a family of proteins called mitogen-activated protein kinases that relay signals inside cells.
- When researchers chemically blocked these pathways, GLP-1 secretion was significantly reduced, confirming their critical role.
- Meat hydrolysate specifically increased the activation (phosphorylation) of ERK1/2 within just 2–15 minutes of exposure.
- Notably, these are the same cellular pathways activated by GLP-1 receptor drugs, suggesting that dietary protein triggers GLP-1 release through the same fundamental biological machinery that pharmaceutical treatments exploit.
This study reveals that eating protein-rich foods, particularly meat, stimulates GLP-1 secretion through the same core cellular pathways targeted by GLP-1 medications like Ozempic. It provides a molecular foundation for understanding why high-protein diets support blood sugar regulation and satiety, and opens the door to the idea that strategic dietary choices could naturally activate some of the same mechanisms that expensive medications are designed to trigger.
PMCID: PMC3838362
PMID: 17065399
Abstract
Glucagon-like peptide-1 (GLP-1) is a potent insulin secretagogue released from L-cells in the intestine. Meat hydrolysate (MH) is a powerful activator of GLP-1 secretion in the human enteroendocrine NCI-H716 cell line, but the mechanisms involved in nutrient-stimulated GLP-1 secretion are poorly understood. The objective of this study was to characterize the intracellular signalling pathways regulating MH- and amino acid-induced GLP-1 secretion. Individually, the pharmacological inhibitors, SB203580 (inhibitor of p38 mitogen-activated protein kinase (MAPK)), wortmannin (inhibitor of phosphatidyl inositol 3-kinase) and U0126 (inhibitor of mitogen activated or extracellular signal-regulated protein kinase (MEK1/2) upstream of extracellular signal-regulated kinase (ERK)1/2) all inhibited MH-induced GLP-1 secretion. Further examination of the MAPK pathway showed that MH increased the phosphorylation of ERK1/2, but not p38 or c-Jun N-terminal kinase over 2–15 min. Incubation with SB203580 resulted in a decrease in phosphorylated p38 MAPK and a concomitant increase in the phosphorylation of ERK1/2. Phosphorylation of ERK1/2 was augmented by co-incubation of MH with SB203580. Inhibitors of protein kinase A and protein kinase C did not inhibit MH-induced GLP-1 secretion. In contrast to non-essential amino acids, essential amino acids (EAAs) increased GLP-1 secretion and similar to MH, activated ERK1/2. However, they also activated p38-suggesting type of protein may affect GLP-1 secretion. In conclusion, there appears to be a crosstalk between p38 and ERK1/2 MAPK in the human enteroendocrine cell with the activation of ERK1/2 common to both MH and EAA. Understanding the cellular pathways involved in nutrient-stimulated GLP-1 secretion has important implications for the design of new treatments aimed at increasing endogenous GLP-1 release in type-2 diabetes and obesity.