Plakoglobin

Quality 0.50 · 1 view · Updated 2 months ago

Mammalian protein found in Homo sapiens

title: "Plakoglobin" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["catenins", "armadillo-repeat-containing-proteins"] description: "Mammalian protein found in Homo sapiens" topic_path: "general/catenins" source: "https://en.wikipedia.org/wiki/Plakoglobin" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Mammalian protein found in Homo sapiens ::

Plakoglobin, also known as junction plakoglobin or gamma-catenin, is a protein that in humans is encoded by the JUP gene. Plakoglobin is a member of the catenin protein family and homologous to β-catenin. Plakoglobin is a cytoplasmic component of desmosomes and adherens junctions structures located within intercalated discs of cardiac muscle that function to anchor sarcomeres and join adjacent cells in cardiac muscle. Mutations in plakoglobin are associated with arrhythmogenic right ventricular dysplasia.

Structure

Human plakoglobin is 81.7 kDa in molecular weight and 745 amino acids long. The JUP gene contains 13 exons spanning 17 kb on chromosome 17q21. Plakoglobin is a member of the catenin family, since it contains a distinct repeating amino acid motif called the armadillo repeat. Plakoglobin is highly similar to β-catenin; both have 12 armadillo repeats as well as N-terminal and C-terminal globular domains of unknown structure. Plakoglobin was originally identified as a component of desmosomes, where it can bind to the cadherin family member desmoglein I. Plakoglobin also associates with classical cadherins such as E-cadherin; in that context, it was called gamma-catenin. Plakoglobin forms distinct complexes with cadherins and desmosomal cadherins.

Function

::figure[src="https://upload.wikimedia.org/wikipedia/commons/a/ae/Simplified_schematic_presentation_of_basic_structural_components_and_molecular_composition_of_intercellular_junctions.jpg" caption="Simplified scheme of cell junctions. TJ, Tight junctions; AJ, Adherens junctions; D, Desmosomes; ZO, Zonula occludens; PG, Plakoglobin, PKP, Plakophilin; DP, Desmoplakin"] ::

Plakoglobin is a major cytoplasmic component of both desmosomes and adherens junctions, and is the only known constituent common to submembranous plaques in both of these structures, which are located at the intercalated disc (ICD) of cardiomyocytes. Plakoglobin links cadherins to the actin cytoskeleton. Plakoglobin binds to conserved regions of desmoglein and desmocollin at intracellular catenin-binding sites to assemble desmosomes.

Plakoglobin is essential for normal development of intercalated discs and stability of cardiac muscle. Transgenic mice homozygous for a null mutation of the JUP gene die around embryonic day 12 from substantial defects in adherens junctions and a lack of functional desmosomes in the heart. Further studies showed that cardiac fibers obtained from JUP-null embryonic mice had decreased passive compliance albeit normal attachment of sarcomeres to adherens junctions.

In additional studies, an inducible cardiac-specific plakoglobin knockout mice were generated. Transgenic mice displayed a similar phenotype as arrhythmogenic right ventricular cardiomyopathy patients, with loss of cardiomyocytes, fibrosis and cardiac dysfunction, as well as alterations in desmosome protein content and gap junction remodeling. Hearts also exhibited increases in β-catenin signaling. Further investigations on the role of β-catenin and plakoglobin in the heart generated a double knockout of these two proteins. Mice exhibited cardiomyopathy, fibrosis, conduction abnormalities and sudden cardiac death, presumably via spontaneous lethal ventricular arrhythmias. Mice also showed a decrease in gap junction structures at intercalated discs.

Intracellular plakoglobin expression is controlled by Wnt signaling and ubiquitin-proteasome-dependent degradation. Phosphorylation of N-terminal Serines by a “destruction complex” composed of glycogen synthase kinase 3β (GSK3β) and scaffold proteins adenomatous polyposis coli (APC) and axin targets plakoglobin for degradation.[31–33]. The phosphorylated motif is recognized by β-TrCP, a ubiquitin ligase that targets plakoglobin 26S proteasome-dependent degradation. Plakoglobin is also O-glycosylated near its N-terminal destruction box.

Clinical significance

Mutation of the JUP gene encoding plakoglobin has been implicated as one of the causes of the cardiomyopathy known as arrhythmogenic right ventricular dysplasia (ARVD) or arrhythmogenic right ventricular cardiomyopathy; mutations in JUP specifically causes an autosomal recessive form referred to as Naxos disease. This form of was first identified in a small cluster of families on the Greek island of Naxos. The phenotype of the Naxos disease variant of ARVD is unique in that it involves the hair and skin as well as the right ventricle. Affected individuals have kinky, wooly hair; there is also palmar and plantar erythema at birth that progresses to keratosis as the palms and soles of the feet are used in crawling and walking. These findings co-segregate 100% with the development of ARVD by early adolescence.

It has become clear that ARVD/ARVC is a disease of the cardiac muscle desmosome; advances in molecular genetics have illuminated this notion.

Studies investigating the role of plakoglobin in disease pathology have found that suppression of desmoplakin expression by siRNA led to the nuclear localization of plakoglobin, resulting in a reduction in Wnt signaling via Tcf/Lef1 and ensued pathogenesis of ARVC. Specifically, adipogenic factor expression was induced and cardiac progenitor cells at the epicardium were differentiated to adipocytes.

Non-invasive cardiac screening identified T-wave inversion, abnormalities in right ventricular wall motion, and frequent ventricular extrasystoles as sensitive and specific markers of a JUP mutation. Additional studies have shown that immunohistochemical analysis of cardiac muscle desmosomal proteins is also a sensitive and specific diagnostic text for ARVD/ARVC.

Abnormal distribution of plakoglobin due to mutations in genes encoding for Desmoglein 1 and 3 have also been implicated in Pemphigus vulgaris.

Interactions

Plakoglobin has been shown to interact with:

References

References

  1. "Entrez Gene: JUP junction plakoglobin".
  2. "Protein sequence of human JUP (Uniprot ID: P14923)".
  3. (October 2000). "Genomic organization and amplification of the human plakoglobin gene (JUP)". Experimental Dermatology.
  4. (October 2007). "Desmosomes from a structural perspective". Current Opinion in Cell Biology.
  5. (September 1986). "Plakoglobin: a protein common to different kinds of intercellular adhering junctions". Cell.
  6. (May 1996). "Desmosomal cadherin binding domains of plakoglobin". The Journal of Biological Chemistry.
  7. (December 1996). "Cadherin binding sites of plakoglobin: localization, specificity and role in targeting to adhering junctions". Journal of Cell Science.
  8. (October 1996). "Targeted mutation of plakoglobin in mice reveals essential functions of desmosomes in the embryonic heart". The Journal of Cell Biology.
  9. (December 1996). "Embryonic heart and skin defects in mice lacking plakoglobin". Developmental Biology.
  10. (January 1999). "Plakoglobin is essential for myocardial compliance but dispensable for myofibril insertion into adherens junctions". Journal of Cellular Biochemistry.
  11. (March 2011). "Cardiac tissue-restricted deletion of plakoglobin results in progressive cardiomyopathy and activation of {beta}-catenin signaling". Molecular and Cellular Biology.
  12. (December 2011). "Restrictive loss of plakoglobin in cardiomyocytes leads to arrhythmogenic cardiomyopathy". Human Molecular Genetics.
  13. (March 2012). "Loss of cadherin-binding proteins β-catenin and plakoglobin in the heart leads to gap junction remodeling and arrhythmogenesis". Molecular and Cellular Biology.
  14. (September 1999). "Axin directly interacts with plakoglobin and regulates its stability". The Journal of Biological Chemistry.
  15. (March 1995). "The APC protein and E-cadherin form similar but independent complexes with alpha-catenin, beta-catenin, and plakoglobin". The Journal of Biological Chemistry.
  16. (February 2000). "Regulation of beta-catenin signaling in the Wnt pathway". Biochemical and Biophysical Research Communications.
  17. (April 2000). "Differential interaction of plakoglobin and beta-catenin with the ubiquitin-proteasome system". Oncogene.
  18. (April 2015). "Normalization of Naxos plakoglobin levels restores cardiac function in mice". The Journal of Clinical Investigation.
  19. (March 2012). "Lack of plakoglobin in epidermis leads to keratoderma". The Journal of Biological Chemistry.
  20. (2006). "Genetic bases of arrhythmogenic right ventricular Cardiomyopathy". Heart International.
  21. (October 2011). "Cardiomyopathy with alopecia and palmoplantar keratoderma (CAPK) is caused by a JUP mutation". The British Journal of Dermatology.
  22. (May 2011). "Lack of plakoglobin leads to lethal congenital epidermolysis bullosa: a novel clinico-genetic entity". Human Molecular Genetics.
  23. (June 2010). "Homozygous mutations in the 5' region of the JUP gene result in cutaneous disease but normal heart development in children". The Journal of Investigative Dermatology.
  24. (2013). "On the diagnostic utility of junction plakoglobin in arrhythmogenic right ventricular cardiomyopathy". Cardiovascular Pathology.
  25. (April 2015). "The ARVD/C genetic variants database: 2014 update". Human Mutation.
  26. (June 2010). "Desmosomal gene analysis in arrhythmogenic right ventricular dysplasia/cardiomyopathy: spectrum of mutations and clinical impact in practice". Europace.
  27. (1993). "GeneReviews® [Internet]". University of Washington, Seattle.
  28. (January 2010). "Multiple mutations in desmosomal proteins encoding genes in arrhythmogenic right ventricular cardiomyopathy/dysplasia". Heart Rhythm.
  29. (October 2009). "Comprehensive desmosome mutation analysis in north americans with arrhythmogenic right ventricular dysplasia/cardiomyopathy". Circulation: Cardiovascular Genetics.
  30. (May 2008). "Mechanisms of disease: molecular genetics of arrhythmogenic right ventricular dysplasia/cardiomyopathy". Nature Clinical Practice. Cardiovascular Medicine.
  31. (May 2007). "Molecular genetics of arrhythmogenic right ventricular cardiomyopathy: emerging horizon?". Current Opinion in Cardiology.
  32. (November 2007). "Role of genetic analysis in the management of patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy". Journal of the American College of Cardiology.
  33. (July 2006). "Suppression of canonical Wnt/beta-catenin signaling by nuclear plakoglobin recapitulates phenotype of arrhythmogenic right ventricular cardiomyopathy". The Journal of Clinical Investigation.
  34. (May 2010). "Arrhythmogenic right ventricular cardiomyopathy is a disease of cardiac stem cells". Current Opinion in Cardiology.
  35. (September 2006). "Arrhythmogenic right ventricular cardiomyopathy caused by deletions in plakophilin-2 and plakoglobin (Naxos disease) in families from Greece and Cyprus: genotype-phenotype relations, diagnostic features and prognosis". European Heart Journal.
  36. (July 2009). "Cardiomyopathies: New test for arrhythmogenic right ventricular cardiomyopathy". Nature Reviews. Cardiology.
  37. (October 2001). "A possible role of catenin dyslocalization in pemphigus vulgaris pathogenesis". Journal of Cutaneous Pathology.
  38. (May 2001). "Catenin dislocation in oral pemphigus vulgaris". Journal of Oral Pathology & Medicine.
  39. (September 1995). "The tyrosine kinase substrate p120cas binds directly to E-cadherin but not to the adenomatous polyposis coli protein or alpha-catenin". Molecular and Cellular Biology.
  40. (June 1998). "A mutation in alpha-catenin disrupts adhesion in clone A cells without perturbing its actin and beta-catenin binding activity". Cell Adhesion and Communication.
  41. (April 1997). "Identification of the domain of alpha-catenin involved in its association with beta-catenin and plakoglobin (gamma-catenin)". The Journal of Biological Chemistry.
  42. (April 1998). "The epidermal growth factor receptor modulates the interaction of E-cadherin with the actin cytoskeleton". The Journal of Biological Chemistry.
  43. (December 2001). "Expression and interaction of different catenins in colorectal carcinoma cells". International Journal of Molecular Medicine.
  44. (August 1994). "Association of plakoglobin with APC, a tumor suppressor gene product, and its regulation by tyrosine phosphorylation". Biochemical and Biophysical Research Communications.
  45. (July 1995). "Tyrosine phosphorylation regulates the adhesions of ras-transformed breast epithelia". The Journal of Cell Biology.
  46. (June 1994). "Dynamics of cadherin/catenin complex formation: novel protein interactions and pathways of complex assembly". The Journal of Cell Biology.
  47. (August 1992). "Plakoglobin, or an 83-kD homologue distinct from beta-catenin, interacts with E-cadherin and N-cadherin". The Journal of Cell Biology.
  48. (August 1995). "Identification of plakoglobin domains required for association with N-cadherin and alpha-catenin". The Journal of Biological Chemistry.
  49. (December 2003). "A novel cell-cell junction system: the cortex adhaerens mosaic of lens fiber cells". Journal of Cell Science.
  50. (August 2000). "Amino-terminal domain of classic cadherins determines the specificity of the adhesive interactions". Journal of Cell Science.
  51. (December 1997). "Alteration of interendothelial adherens junctions following tumor cell-endothelial cell interaction in vitro". Experimental Cell Research.
  52. (June 2002). "Histamine stimulates phosphorylation of adherens junction proteins and alters their link to vimentin". American Journal of Physiology. Lung Cellular and Molecular Physiology.
  53. (November 2001). "Isoform-specific differences in the size of desmosomal cadherin/catenin complexes". The Journal of Investigative Dermatology.
  54. (May 2000). "The amino- and carboxyl-terminal tails of (beta)-catenin reduce its affinity for desmoglein 2". Journal of Cell Science.
  55. (November 1995). "The fourth armadillo repeat of plakoglobin (gamma-catenin) is required for its high affinity binding to the cytoplasmic domains of E-cadherin and desmosomal cadherin Dsg2, and the tumor suppressor APC protein". Journal of Biochemistry.
  56. (October 1998). "VE-cadherin and desmoplakin are assembled into dermal microvascular endothelial intercellular junctions: a pivotal role for plakoglobin in the recruitment of desmoplakin to intercellular junctions". Journal of Cell Science.
  57. (November 1997). "The amino-terminal domain of desmoplakin binds to plakoglobin and clusters desmosomal cadherin-plakoglobin complexes". The Journal of Cell Biology.
  58. (August 2003). "Heregulin targets gamma-catenin to the nucleolus by a mechanism dependent on the DF3/MUC1 oncoprotein". Molecular Cancer Research.
  59. (March 2002). "Protein binding and functional characterization of plakophilin 2. Evidence for its diverse roles in desmosomes and beta -catenin signaling". The Journal of Biological Chemistry.
  60. (July 1996). "Association of human protein-tyrosine phosphatase kappa with members of the armadillo family". The Journal of Biological Chemistry.
  61. (October 2006). "Intracellular substrates of brain-enriched receptor protein tyrosine phosphatase rho (RPTPrho/PTPRT)". Brain Research.
  62. (May 2001). "Adult mice deficient in actinin-associated LIM-domain protein reveal a developmental pathway for right ventricular cardiomyopathy". Nature Medicine.

::callout[type=info title="Wikipedia Source"] This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page. ::

cateninsarmadillo-repeat-containing-proteins