OCLN gene

The OCLN gene (Occludin) is a protein coding gene localized on chrom0some 5q13.2. This gene encodes an integral membrane protein(occludin) that is required for cytokine-induced regulation of the paracellular permeability barrier of tight junctions. Alternative splicing leads to several transcript variants. An important paralog of this gene is MARVELD2. A related pseudogene is located 1.5 Mb downstream on the q arm of chromosome 5.

The membrane protein occludin is able to induce adhesion when expressed in cells lacking tight junctions. Occludin acts as a co-receptor for the hepatitis C virus (HCV) in hepatocytes.

Mutations in this gene are thought to be the cause of band-like calcification with simplified gyrations and polymicrogyria (BLC-PMG - Jenkinson EM et al. 2018), an autosomal recessive neurological disorder also known as pseudo-TORCH syndrome (Ekinci F et al. 2020).

1. Bamforth SD et al. (1999) A dominant mutant of occludin disrupts tight junction structure and function. J Cell Sci 112: 1879-1888.
2. Ekinci F et al. (2020) A homozygous frameshift mutation in OCLN gene result in Pseudo-TORCH syndrome type I: A case report extending the phenotype with central diabetes insipidus and renal dysfunction. Eur J Med Genet 63:103923.
3. Jenkinson EM et al. (2018) Comprehensive molecular screening strategy of OCLN in band-like calcification with simplified gyration and polymicrogyria. Clin Genet 93:228-234.
4. Furuse M et al. (1993) Occludin a novel integral membrane protein localizing at tight junctions. In: J Cell Biol 123: 1777-1788.
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6. Kuo WT et al. (2022) Tight junction proteins occludin and ZO-1 as regulators of epithelial proliferation and survival. Ann N Y Acad Sci 1514:21-33.
7. Kuo WT et al. (2019) Inflammation-induced Occludin Downregulation Limits Epithelial Apoptosis by Suppressing Caspase-3 Expression. Gastroenterology 157:1323-1337.
8. Mankertz J etal. (2002) Gene expression of the tight junction protein occludin includes differential splicing and alternative promoter usage. Biochem Biophys Res Commun 298: 657-66
9. Muresan Z et al. (2000) Occludin 1B, a variant of the tight junction protein occludin. Mol Biol Cell 11: 627-634.
10. Sugita K et al. (2020) Tight junctions in the development of asthma, chronic rhinosinusitis, atopic dermatitis, eosinophilic esophagitis, and inflammatory bowel diseases. J Leukoc Biol 107:749-762.