Tight junction
Cellular tight junction en.svg
Diagram of Tight junction
Details
Identifiers
Latinjunctio occludens
MeSHD019108
THH1.00.01.1.02007
FMA67397
Anatomical terminology

Tight junctions, also known as occluding junctions or zonulae occludentes (singular, zonula occludens) are multiprotein junctional complexes whose canonical function is to prevent leakage of solutes and water and seals between the epithelial cells. Tight junctions may also serve as leaky pathways by forming selective channels for small cations, anions, or water. Tight junctions are present mostly in vertebrates (with the exception of Tunicates[1]). The corresponding junctions that occur in invertebrates are septate junctions.

Structure

Tight junctions are composed of a branching network of sealing strands, each strand acting independently from the others. Therefore, the efficiency of the junction in preventing ion passage increases exponentially with the number of strands. Each strand is formed from a row of transmembrane proteins embedded in both plasma membranes, with extracellular domains joining one another directly. There are at least 40 different proteins composing the tight junctions.[2] These proteins consist of both transmembrane and cytoplasmic proteins. The three major transmembrane proteins are occludin, claudins, and junction adhesion molecule (JAM) proteins. These associate with different peripheral membrane proteins such as ZO-1 located on the intracellular side of plasma membrane, which anchor the strands to the actin component of the cytoskeleton.[3] Thus, tight junctions join together the cytoskeletons of adjacent cells.

Depiction of the transmembrane proteins that make up tight junctions: occludin, claudins, and JAM proteins.
Depiction of the transmembrane proteins that make up tight junctions: occludin, claudins, and JAM proteins.

Transmembrane proteins:

Functions

They perform vital functions:[11]

Classification

Epithelia are classed as "tight" or "leaky", depending on the ability of the tight junctions to prevent water and solute movement:[14]

See also

TEM of negatively stained proximal convoluted tubule of Rat kidney tissue at a magnification of ~55,000x and 80 kV with Tight junction. Note that the three dark lines of density correspond to the density of the protein complex, and the light lines in between correspond to the paracellular space.
TEM of negatively stained proximal convoluted tubule of Rat kidney tissue at a magnification of ~55,000x and 80 kV with Tight junction. Note that the three dark lines of density correspond to the density of the protein complex, and the light lines in between correspond to the paracellular space.

References

  1. ^ Banerjee, Swati; Sousa, Aurea D.; Bhat, Manzoor A. (2006). "Organization and Function of Septate Junctions: An Evolutionary Perspective". Cell Biochemistry and Biophysics. 46 (1): 65–78. doi:10.1385/CBB:46:1:65. ISSN 1085-9195. PMID 16943624. S2CID 3119021.
  2. ^ Itallie, Christina M. Van; Anderson, James M. (2009-08-01). "Physiology and Function of the Tight Junction". Cold Spring Harbor Perspectives in Biology. 1 (2): a002584. doi:10.1101/cshperspect.a002584. ISSN 1943-0264. PMC 2742087. PMID 20066090.
  3. ^ Anderson, JM; Van Itallie, CM (August 2009). "Physiology and function of the tight junction". Cold Spring Harb Perspect Biol. 1 (2): a002584. doi:10.1101/cshperspect.a002584. PMC 2742087. PMID 20066090.
  4. ^ Wolburg, Hartwig; Lippoldt, Andrea; Ebnet, Klaus (2006), "Tight Junctions and the Blood-Brain Barrier", Tight Junctions, Springer US, pp. 175–195, doi:10.1007/0-387-36673-3_13, ISBN 9780387332017
  5. ^ Liu, Wei-Ye; Wang, Zhi-Bin; Zhang, Li-Chao; Wei, Xin; Li, Ling (2012-06-12). "Tight Junction in Blood-Brain Barrier: An Overview of Structure, Regulation, and Regulator Substances". CNS Neuroscience & Therapeutics. 18 (8): 609–615. doi:10.1111/j.1755-5949.2012.00340.x. ISSN 1755-5930. PMC 6493516. PMID 22686334.
  6. ^ Schneeberger, Eveline E.; Lynch, Robert D. (June 2004). "The tight junction: a multifunctional complex" (PDF). American Journal of Physiology. Cell Physiology. 286 (6): C1213–C1228. doi:10.1152/ajpcell.00558.2003. ISSN 0363-6143. PMID 15151915. S2CID 1725292. Archived from the original (PDF) on 2019-02-22.
  7. ^ Mitic, Laura L.; Van Itallie, Christina M.; Anderson, James M. (August 2000). "Molecular Physiology and Pathophysiology of Tight Junctions I. Tight junction structure and function: lessons from mutant animals and proteins" (PDF). American Journal of Physiology. Gastrointestinal and Liver Physiology. 279 (2): G250–G254. doi:10.1152/ajpgi.2000.279.2.g250. ISSN 0193-1857. PMID 10915631. S2CID 32634345. Archived from the original (PDF) on 2019-03-09.
  8. ^ Luissint, Anny-Claude; Artus, Cédric; Glacial, Fabienne; Ganeshamoorthy, Kayathiri; Couraud, Pierre-Olivier (2012-11-09). "Tight junctions at the blood brain barrier: physiological architecture and disease-associated dysregulation". Fluids and Barriers of the CNS. 9 (1): 23. doi:10.1186/2045-8118-9-23. ISSN 2045-8118. PMC 3542074. PMID 23140302.
  9. ^ Masuda, Sayuri; Oda, Yukako; Sasaki, Hiroyuki; Ikenouchi, Junichi; Higashi, Tomohito; Akashi, Masaya; Nishi, Eiichiro; Furuse, Mikio (2011-02-15). "LSR definescell corners for tricellular tight junction formation in epithelial cells". Journal of Cell Science. 124 (Part 4): 548–555. doi:10.1242/jcs.072058. PMID 21245199.
  10. ^ Higashi, Tomohito; Miller, Ann (2017-07-15). "Tricellular junctions: how to build junctions at the TRICkiest points of epithelial cells". Molecular Biology of the Cell. 28 (15): 2023–2034. doi:10.1091/mbc.E16-10-0697. ISSN 1939-4586. PMC 5509417. PMID 28705832.
  11. ^ Department, Biology. "Tight Junctions (and other cellular connections)". Davidson College. Retrieved 2015-01-12.
  12. ^ Chalcroft, J. P.; Bullivant, S (1970). "An interpretation of liver cell membrane and junction structure based on observation of freeze-fracture replicas of both sides of the fracture". The Journal of Cell Biology. 47 (1): 49–60. doi:10.1083/jcb.47.1.49. PMC 2108397. PMID 4935338.
  13. ^ Guo, P; Weinstein, AM; Weinbaum, S (Aug 2003). "A dual-pathway ultrastructural model for the tight junction of rat proximal tubule epithelium" (PDF). American Journal of Physiology. Renal Physiology. 285 (2): F241–57. doi:10.1152/ajprenal.00331.2002. PMID 12670832. S2CID 22824832. Archived from the original (PDF) on 2019-02-22.
  14. ^ Department, Biology. "Tight Junctions and other cellular connections". Davidson College. Retrieved 2013-09-20.