Addressin

MADCAM1
Available structures PDB Human UniProt search: PDBe RCSB List of PDB id codes 1BQS, 1GSM, 4HBQ, 4HC1, 4HCR, 4HD9
Identifiers
Aliases	MADCAM1, MACAM1, mucosal vascular addressin cell adhesion molecule 1
External IDs	OMIM: 102670 GeneCards: MADCAM1
Gene location (Human) Chr. Chromosome 19 (human) Band 19p13.3 Start 489,176 bp End 505,343 bp
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in appendix spleen cingulate gyrus Brodmann area 9 prefrontal cortex cardia fundus amygdala body of stomach duodenum n/a More reference expression data BioGPS n/a
Gene ontology Molecular function integrin binding involved in cell-matrix adhesion Cellular component integral component of membrane plasma membrane membrane Biological process leukocyte tethering or rolling heterotypic cell-cell adhesion cell adhesion cell-matrix adhesion extracellular matrix organization receptor clustering immune response signal transduction regulation of immune response positive regulation of leukocyte migration integrin-mediated signaling pathway positive regulation of lymphocyte migration Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 8174 n/a Ensembl ENSG00000099866 n/a UniProt Q13477 n/a RefSeq (mRNA) NM_130762 NM_130760 n/a RefSeq (protein) NP_570116 NP_570118 n/a Location (UCSC) Chr 19: 0.49 – 0.51 Mb n/a PubMed search n/a
Wikidata
View/Edit Human

Mucosal vascular addressin cell adhesion molecule 1 (MAdCAM-1) is a protein that in humans is encoded by the MADCAM1 gene. The protein encoded by this gene is an endothelial cell adhesion molecule that interacts preferentially with the leukocyte beta7 integrin LPAM-1 (alpha4 / beta7), L-selectin, and VLA-4 (alpha4 / beta1) on myeloid cells to direct leukocytes into mucosal and inflamed tissues. It is a member of the immunoglobulin superfamily and is similar to ICAM-1 and VCAM-1.

Nomenclature

Addressin is a lesser-used term to describe the group of adhesion molecules that are involved with lymphocyte homing, commonly found at high-endothelial venules (HEVs) where lymphocytes exit the blood and enter the lymph node. Addressins are the ligands to the homing receptors of lymphocytes. The task of these ligands and their receptors is to determine which tissue the lymphocyte will enter next. They carry carbohydrates in order to be recognized by L-selectin. Addressins physically bind to mobile lymphocytes to guide them to the HEVs. Examples of molecules that are often referred to as addressins are CD34 and GlyCAM-1 on HEVs in peripheral lymph nodes, and MAdCAM-1 on endothelial cells in the intestine.

Function

In terms of migration, MAdCAM-1 is selectively expressed on mucosal endothelial cells, driving memory T-cell re-circulation through mucosal tissues. In contrast, and indeed the main difference between the two molecules, ICAM molecules are involved with naïve T-cell re-circulation. Whereas MAdCAM-1 is selectively expressed, ICAM is broadly expressed on inflamed endothelium.

Peripheral node addressins

Peripheral node addressins (PNAd) are carbohydrate residues that are lymphocyte homing receptor ligands that are expressed on the HEVs of peripheral lymph nodes. These proteins collectively bind to L-selectin to guide lymphocytes such as mature naïve B and T cells into the lymph node. During the development of secondary lymphoid organs, PNAd expression is upregulated following the upregulation and subsequent downregulation of MAdCAM-1 on HEVs. PNAd expression, as well as the expression of MAdCAM-1, is dependent on lymphotoxin signaling in the HEVs of lymph nodes.

Clinical significance

In inflammatory bowel diseases, MAdCAM-1 can be overexpressed on the endothelial cells of intestinal mucosa and gut‐associated lymphoid tissue, leading to excessive inflammation in the gut. A potential therapeutic target to manage these diseases could be the MAdCAM-1 molecules that are expressed on these cells and bring in lymphocytes. One example of a potential therapy is the fully human monoclonal antibody ontamalimab that targets and binds to MAdCAM-1, preventing it from interacting with the integrins on the surface of the lymphocytes.

See also

• CD34
• GLYCAM1
• Integrin β7 - a constituent of α₄β₇

Further reading

External links

• vascular+addressins at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
• Human MADCAM1 genome location and MADCAM1 gene details page in the UCSC Genome Browser.
• Overview of all the structural information available in the PDB for UniProt: Q13477 (Mucosal addressin cell adhesion molecule 1) at the PDBe-KB.

This article incorporates text from the United States National Library of Medicine, which is in the public domain.