Tight junctions
Multicellular organisms are separated from external environment by a layer of
epithelial cells whose integrity is maintained by intercellular junction complexes
composed of tight junctions (TJ), adherens junctions, and desmosomes. Tight cell
junctions serve as a physical barrier to prevent solutes and water from passing freely
through the paracellular space between epithelial or endothelial cell sheets.
A group of integral membrane proteins, Occludin,
Claudins, and Junction adhesion molecules (JAM
1, JAM 2 and JAM3), interact with an
increasingly complex array of tight junction plaque proteins to regulate paracellular
solute and water flux and integrate other diverse cell functions [1].
TJ plaque proteins, such as Zonula occludens ZO-1,
ZO-2 and ZO-3, serve as links
between the integral TJ proteins and the Actin cytoskeleton
and as adapters for the recruitment of cytosolic molecules implicated in cell signaling
[2].
Actin filament-binding protein AF-6 serves as a linker of
the Actin cytoskeleton to the plasma membrane at the TJ
sites [3].
Cingulin is a functionally important component of TJ. It
links the submembrane plaque domain of TJ to the actomyosin cytoskeleton [4].
Multi-PDZ domain protein 1 (MUPP1) accumulates at the TJ
in epithelial cells through its binding to Claudins and
JAMs. MUPP1 is believed to function as a multivalent
scaffold protein that recruits various proteins to TJ [5].
Metadherin (LYRIC) colocalizes with
ZO-1 and Occludin in polarized
epithelial cells. This protein is most likely not involved
in the TJ formation as a structural component. However, it is required for the maturation
of the TJ complex [6].
Interactions between Nectin (Prr1),
AF-6 and Occludin suggest a
role of the nectin-afadin system in the organization of TJs in epithelial cells [7].
WNK lysine deficient protein kinase 4 (WNK4)
phosphorylates Claudins 1-4 involved in the regulation of
paracellular ion permeability [8].
ZO-1-associated Y-box factor ZONAB
(CSDA) regulates epithelial cell proliferation and cell
density [9].
Transcription factors Tcf(Lef),
TITF1, CDX1,
CDX2 and SNAIL1 are involved in
the transcriptional regulation of expression of the genes
encoding TJ proteins [1].
References:
- Schneeberger EE, Lynch RD
The tight junction: a multifunctional complex.
American journal of physiology. Cell physiology 2004 Jun;286(6):C1213-28
- Itoh M, Furuse M, Morita K, Kubota K, Saitou M, Tsukita S
Direct binding of three tight junction-associated MAGUKs, ZO-1, ZO-2, and ZO-3, with the COOH termini of claudins.
The Journal of cell biology 1999 Dec 13;147(6):1351-63
- Mandai K, Nakanishi H, Satoh A, Obaishi H, Wada M, Nishioka H, Itoh M, Mizoguchi A, Aoki T, Fujimoto T, Matsuda Y, Tsukita S, Takai Y
Afadin: A novel actin filament-binding protein with one PDZ domain localized at cadherin-based cell-to-cell adherens junction.
The Journal of cell biology 1997 Oct 20;139(2):517-28
- Cordenonsi M, D'Atri F, Hammar E, Parry DA, Kendrick-Jones J, Shore D, Citi S
Cingulin contains globular and coiled-coil domains and interacts with ZO-1, ZO-2, ZO-3, and myosin.
The Journal of cell biology 1999 Dec 27;147(7):1569-82
- Hamazaki Y, Itoh M, Sasaki H, Furuse M, Tsukita S
Multi-PDZ domain protein 1 (MUPP1) is concentrated at tight junctions through its possible interaction with claudin-1 and junctional adhesion molecule.
The Journal of biological chemistry 2002 Jan 4;277(1):455-61
- Britt DE, Yang DF, Yang DQ, Flanagan D, Callanan H, Lim YP, Lin SH, Hixson DC
Identification of a novel protein, LYRIC, localized to tight junctions of polarized epithelial cells.
Experimental cell research 2004 Oct 15;300(1):134-48
- Fukuhara A, Irie K, Yamada A, Katata T, Honda T, Shimizu K, Nakanishi H, Takai Y
Role of nectin in organization of tight junctions in epithelial cells.
Genes to cells : devoted to molecular & cellular mechanisms 2002 Oct;7(10):1059-72
- Yamauchi K, Rai T, Kobayashi K, Sohara E, Suzuki T, Itoh T, Suda S, Hayama A, Sasaki S, Uchida S
Disease-causing mutant WNK4 increases paracellular chloride permeability and phosphorylates claudins.
Proceedings of the National Academy of Sciences of the United States of America 2004 Mar 30;101(13):4690-4
- Balda MS, Garrett MD, Matter K
The ZO-1-associated Y-box factor ZONAB regulates epithelial cell proliferation and cell density.
The Journal of cell biology 2003 Feb 3;160(3):423-32
