GLP-2 (Glucagon-Like Peptide 2)

Overview

Glucagon-Like Peptide-2 (GLP-2) is a 33-amino acid peptide hormone produced by intestinal L-cells from the proglucagon precursor, released alongside GLP-1, oxyntomodulin, and PYY in response to meals. While its sibling peptide GLP-1 has achieved enormous prominence as a metabolic drug target, GLP-2 has occupied a distinct niche in gut physiology: it is the principal humoral regulator of intestinal mucosal growth, barrier function, and absorptive capacity.

The name reflects GLP-2's position within the proglucagon gene product, as the second "glucagon-like" peptide discovered after GLP-1. Proglucagon is processed differently in pancreatic α-cells (yielding glucagon) and intestinal L-cells (yielding GLP-1, GLP-2, and oxyntomodulin). Both GLP peptides derive from adjacent regions of the same precursor and share structural features, but their receptors (GLP1R and GLP2R) are distinct and non-cross-reactive.

Physiologically, GLP-2 is "intestinotrophic" — it promotes proliferation of intestinal crypt cells, increases villus height, enhances mucosal mass, and maintains epithelial barrier integrity. These effects make GLP-2 of particular interest in short bowel syndrome, inflammatory bowel disease, intestinal ischemia-reperfusion injury, chemotherapy-induced mucositis, and other conditions characterized by compromised intestinal mucosa. The GLP-2 analog teduglutide (Gly²-GLP-2, Revestive/Gattex) has been developed as a treatment for short bowel syndrome, validating the GLP-2 pathway therapeutically.

Structure/Sequence

Human GLP-2: HADGSFSDEMNTILDNLAARDFINWLIQTKITD-OH

• Length: 33 amino acids
• Molecular weight: ~3,921 g/mol
• Gene: GCG (shared with glucagon and GLP-1, chromosome 2q24.2)
• Position in proglucagon: Residues 126-158 of 180-aa preproglucagon
• Free C-terminus: Not amidated
• N-terminal His-Ala: DPP-4 cleavage site; rapid inactivation

Relationship to GLP-1

• GLP-1: HAEGTFTSDVSSYLEGQAAKEFIAWLVKGR(G) (from proglucagon 98-128)
• GLP-2: HADGSFSDEMNTILDNLAARDFINWLIQTKITD (proglucagon 126-158)
• Both peptides share N-terminal His-Ala dipeptide vulnerable to DPP-4
• Approximately 50% sequence similarity
• Distinct receptors (GLP1R vs GLP2R), not cross-reactive

Teduglutide Modification

Teduglutide is [Gly²]-GLP-2 — alanine at position 2 is replaced with glycine. This single substitution makes the N-terminus resistant to DPP-4 cleavage, extending plasma half-life from minutes to hours and enabling once-daily subcutaneous dosing.

Species Conservation

GLP-2 sequence is highly conserved across mammals. The intestinotrophic activity is also conserved.

Mechanism of Action

GLP-2 Receptor (GLP2R)

GLP-2 signals through the GLP-2 receptor:

• G-protein coupling: Gs primarily, with some Gq coupling
• Activates adenylyl cyclase → elevated cAMP
• Downstream: PKA activation, CREB phosphorylation, expression of growth-related genes
• Expression: Restricted to intestinal subepithelial myofibroblasts, enteric neurons, and some CNS regions
• Notable: GLP2R is NOT expressed on intestinal epithelial cells themselves — GLP-2 effects on epithelium are indirect through mesenchymal cells that release growth factors

Indirect Epithelial Signaling

Because GLP2R is expressed on subepithelial myofibroblasts, enteroendocrine cells, and enteric neurons — not on epithelial cells — GLP-2 growth effects on epithelium are mediated through paracrine release of:

• IGF-1 (insulin-like growth factor 1) — major mediator
• Keratinocyte growth factor (KGF)
• Epidermal growth factor (EGF)
• Signaling from stromal cells to epithelium drives crypt proliferation

Intestinal Effects

• Increased crypt cell proliferation and villus elongation
• Enhanced mucosal mass in small intestine and colon
• Improved nutrient absorption via expanded absorptive surface
• Reduced apoptosis in crypt and villus enterocytes
• Improved intestinal barrier function (tight junction integrity)
• Delayed gastric emptying (smaller effect than GLP-1)

Gastric Acid and Motility

• Reduces gastric acid secretion
• Reduces gastric motility (contributing to delayed gastric emptying)

Immune Effects

• Reduces intestinal inflammation in animal models (IBD, enteritis)
• Modulates Paneth cell defensin production
• Anti-apoptotic on enterocytes during inflammatory or ischemic injury

Postprandial Release

• Released from L-cells in response to luminal nutrients
• Biphasic release similar to GLP-1
• Plasma GLP-2 rises within 15-30 minutes of eating
• Rapid DPP-4 inactivation (half-life ~7 minutes for native GLP-2)

Research Summary

Common Discussion Topics

1. Indirect epithelial effects — The absence of GLP2R on the intestinal epithelium itself is a remarkable feature of GLP-2 biology. Epithelial growth effects are mediated through stromal cells (myofibroblasts) that release paracrine growth factors, making GLP-2 an indirect mucosal growth factor. This architecture parallels other mesenchymal-epithelial signaling systems.

2. Teduglutide and short bowel syndrome — Teduglutide (Gattex/Revestive) represents a clear translation of GLP-2 biology to therapy. Patients with short bowel syndrome dependent on parenteral nutrition can reduce their intravenous feeding requirements, sometimes substantially, with daily teduglutide. This is a paradigm case of peptide hormone replacement for anatomical gut loss.

3. Co-secretion with GLP-1 — GLP-1 and GLP-2 are released in parallel from L-cells but have entirely different physiological emphases — GLP-1 is metabolic/satiety/insulinotropic; GLP-2 is intestinotrophic. This demonstrates how co-released hormones can have specialized, non-overlapping roles despite shared origin.

4. Therapeutic diversification — Beyond short bowel syndrome, GLP-2 analogs are being investigated for chemotherapy-induced mucositis, inflammatory bowel disease, radiation enteritis, intestinal ischemia-reperfusion, and stress-induced intestinal hyperpermeability. This reflects the broad relevance of mucosal barrier and growth biology.

5. DPP-4 resistance strategy — The Ala²→Gly substitution of teduglutide, extending half-life from minutes to hours, exemplifies a general strategy for GLP family peptides (and for DPP-4–sensitive peptides more broadly). Similar modifications underlie many modern metabolic peptide drugs.

Related Compounds

• Glucagon — parent proglucagon product
• Semaglutide — GLP-1 receptor agonist
• Oxyntomodulin — co-secreted dual-agonist proglucagon product
• Peptide YY — co-secreted L-cell satiety peptide