CASK explained

Peripheral plasma membrane protein CASK is a protein that in humans is encoded by the CASK gene.^{[1] [2]} This gene is also known by several other names: CMG 2 (CAMGUK protein 2), calcium/calmodulin-dependent serine protein kinase 3 and membrane-associated guanylate kinase 2. CASK gene mutations are the cause of XL-ID with or without nystagmus and MICPCH, an X-linked neurological disorder.

Gene

This gene is located on the short arm of the X chromosome (Xp11.4). It is 404,253 bases in length and lies on the Crick (minus) strand. The encoded protein has 926 amino acids with a predicted molecular weight of 105,123 daltons.

Function

This protein is a multidomain scaffolding protein with a role in synaptic transmembrane protein anchoring and ion channel trafficking. It interacts with the transcription factor TBR1 and binds to several cell-surface proteins including neurexins and syndecans.

Clinical importance

This gene has been implicated in X-linked mental retardation,^[3] including specifically mental retardation and microcephaly with pontine and cerebellar hypoplasia.^[4] The role of CASK in disease is primarily associated with a loss of function (under expression) of the CASK gene as a result of a deletion, missense or splice mutation.^[5] It appears that mutations in the gene lead to diminished amounts of the protein being coded. As a result, CASK is unable to form complexes with other proteins leading to a cascade of events. Research has shown there is significant down-regulation of the genes involved in pre-synaptic development and of CASK protein interactors.^[6]

Males affected by CASK variants tend to have more severe symptoms than females due to the X-linked nature of the disease. These genetic issues are often fatal in the womb for male embryos^{[7] [8]} or else lead to infant mortality. Females with CASK mutations have variable phenotypes with moderate to severe intellectual disability. CASK missense mutations and some splice mutations can lead to the milder neurodevelopmental phenotype.

CASK related disorders are mainly found in girls. The prevalence is unknown but generally thought to be below 400 cases worldwide. Patients are often born healthy but within the first few months of life show progressive microcephaly. Although there can be prenatal deceleration of head circumference growth, the majority of cases will not be diagnosed according to current recommendations for fetal CNS routine assessment.^[9]

The exact mode of pathology is not clear, but evidence from mice models indicates CASK deficiency in neurones causes the following effects:^[10]

• reduced levels of associated proteins such as Mint1^[11] and neurexin
• Higher levels of Neuroligin 1
• Increased glutamate release at synapses and reduced GABA release affecting the E/I balance in maturing neural circuits^[12]
• Down-regulation of GluN2B resulting in disruption of synaptic E/I balance^[13]

Even slight changes in CASK expression in humans leads to dysregulation of the formation of presynapses, especially in inhibitory neurones.^[6]

Interactions

CASK has been shown to interact with:

• KCNJ4^{[14] [15]}
• APBA1^[16]
• ATP2B4^[17]
• CINAP and TBR1^[18]
• DLG1^{[15] [19]}
• DLG4^[20]
• F11 receptor^{[21] [22]}
• ID1^[23]
• KCNJ12^{[14] [15]}
• LIN7A^{[15] [24]}
• Nephrin^[25]
• Parkin (ligase)^[26]
• RPH3A^[27]
• SDC2^{[27] [28]}

External links

• CASK Research Foundation - A non-profit based in the UK for research, information and support into CASK related disorders including MICPCH
• Angelina CASK Neurological Research Foundation - A non-profit based in Australia creating research grants for research into CASK gene related disorders.

Further reading

• Zhu ZQ, Wang D, Xiang D, Yuan YX, Wang Y . Calcium/calmodulin-dependent serine protein kinase is involved in exendin-4-induced insulin secretion in INS-1 cells . Metabolism . 63 . 1 . 120–126 . January 2014 . 24140090 . 10.1016/j.metabol.2013.09.009 .
• Wang Y, Li R, Du D, Zhang C, Yuan H, Zeng R, Chen Z . Proteomic analysis reveals novel molecules involved in insulin signaling pathway . Journal of Proteome Research . 5 . 4 . 846–855 . April 2006 . 16602692 . 10.1021/pr050391m . 10.1.1.583.5128 .
• Mukherjee K, Slawson JB, Christmann BL, Griffith LC . Neuron-specific protein interactions of Drosophila CASK-β are revealed by mass spectrometry . Frontiers in Molecular Neuroscience . 7 . 58 . 2014 . 25071438 . 4075472 . 10.3389/fnmol.2014.00058 . free .
• Wei JL, Fu ZX, Fang M, Zhou QY, Zhao QN, Guo JB, Lu WD, Wang H . 6 . High expression of CASK correlates with progression and poor prognosis of colorectal cancer . Tumour Biology . 35 . 9 . 9185–9194 . September 2014 . 24927672 . 10.1007/s13277-014-2179-3 . 1809280 .
• Hata Y, Butz S, Südhof TC . CASK: a novel dlg/PSD95 homolog with an N-terminal calmodulin-dependent protein kinase domain identified by interaction with neurexins . The Journal of Neuroscience . 16 . 8 . 2488–2494 . April 1996 . 8786425 . 6578772 . 10.1523/JNEUROSCI.16-08-02488.1996 . free .
• Daniels DL, Cohen AR, Anderson JM, Brünger AT . Crystal structure of the hCASK PDZ domain reveals the structural basis of class II PDZ domain target recognition . Nature Structural Biology . 5 . 4 . 317–325 . April 1998 . 9546224 . 10.1038/nsb0498-317 . 20608889 .
• Hsueh YP, Yang FC, Kharazia V, Naisbitt S, Cohen AR, Weinberg RJ, Sheng M . Direct interaction of CASK/LIN-2 and syndecan heparan sulfate proteoglycan and their overlapping distribution in neuronal synapses . The Journal of Cell Biology . 142 . 1 . 139–151 . July 1998 . 9660869 . 2133027 . 10.1083/jcb.142.1.139 .
• Butz S, Okamoto M, Südhof TC . A tripartite protein complex with the potential to couple synaptic vesicle exocytosis to cell adhesion in brain . Cell . 94 . 6 . 773–782 . September 1998 . 9753324 . 10.1016/S0092-8674(00)81736-5 . free .
• Borg JP, Straight SW, Kaech SM, de Taddéo-Borg M, Kroon DE, Karnak D, Turner RS, Kim SK, Margolis B . 6 . Identification of an evolutionarily conserved heterotrimeric protein complex involved in protein targeting . The Journal of Biological Chemistry . 273 . 48 . 31633–31636 . November 1998 . 9822620 . 10.1074/jbc.273.48.31633 . free .
• Borg JP, Lõpez-Figueroa MO, de Taddèo-Borg M, Kroon DE, Turner RS, Watson SJ, Margolis B . Molecular analysis of the X11-mLin-2/CASK complex in brain . The Journal of Neuroscience . 19 . 4 . 1307–1316 . February 1999 . 9952408 . 6786035 . 10.1523/JNEUROSCI.19-04-01307.1999 . free .
• Maximov A, Südhof TC, Bezprozvanny I . Association of neuronal calcium channels with modular adaptor proteins . The Journal of Biological Chemistry . 274 . 35 . 24453–24456 . August 1999 . 10455105 . 10.1074/jbc.274.35.24453 . free .
• Hsueh YP, Sheng M . Regulated expression and subcellular localization of syndecan heparan sulfate proteoglycans and the syndecan-binding protein CASK/LIN-2 during rat brain development . The Journal of Neuroscience . 19 . 17 . 7415–7425 . September 1999 . 10460248 . 6782500 . 10.1523/JNEUROSCI.19-17-07415.1999 . free .
• Hsueh YP, Wang TF, Yang FC, Sheng M . Nuclear translocation and transcription regulation by the membrane-associated guanylate kinase CASK/LIN-2 . Nature . 404 . 6775 . 298–302 . March 2000 . 10749215 . 10.1038/35005118 . 4415747 . 2000Natur.404..298H .
• Ebnet K, Schulz CU, Meyer Zu Brickwedde MK, Pendl GG, Vestweber D . Junctional adhesion molecule interacts with the PDZ domain-containing proteins AF-6 and ZO-1 . The Journal of Biological Chemistry . 275 . 36 . 27979–27988 . September 2000 . 10856295 . 10.1074/jbc.M002363200 . free.
• Nix SL, Chishti AH, Anderson JM, Walther Z . hCASK and hDlg associate in epithelia, and their src homology 3 and guanylate kinase domains participate in both intramolecular and intermolecular interactions . The Journal of Biological Chemistry . 275 . 52 . 41192–41200 . December 2000 . 10993877 . 10.1074/jbc.M002078200 . free .
• Stevenson D, Laverty HG, Wenwieser S, Douglas M, Wilson JB . Mapping and expression analysis of the human CASK gene . Mammalian Genome . 11 . 10 . 934–937 . October 2000 . 11003712 . 10.1007/s003350010170 . 35231493 .
• Biederer T, Südhof TC . Mints as adaptors. Direct binding to neurexins and recruitment of munc18 . The Journal of Biological Chemistry . 275 . 51 . 39803–39806 . December 2000 . 11036064 . 10.1074/jbc.C000656200 . free .
• Martinez-Estrada OM, Villa A, Breviario F, Orsenigo F, Dejana E, Bazzoni G . Association of junctional adhesion molecule with calcium/calmodulin-dependent serine protein kinase (CASK/LIN-2) in human epithelial caco-2 cells . The Journal of Biological Chemistry . 276 . 12 . 9291–9296 . March 2001 . 11120739 . 10.1074/jbc.M006991200 . free .
• Hsueh YP, Roberts AM, Volta M, Sheng M, Roberts RG . Bipartite interaction between neurofibromatosis type I protein (neurofibromin) and syndecan transmembrane heparan sulfate proteoglycans . The Journal of Neuroscience . 21 . 11 . 3764–3770 . June 2001 . 11356864 . 6762697 . 10.1523/JNEUROSCI.21-11-03764.2001 . free .
• Zhang Y, Luan Z, Liu A, Hu G . The scaffolding protein CASK mediates the interaction between rabphilin3a and beta-neurexins . FEBS Letters . 497 . 2–3 . 99–102 . May 2001 . 11377421 . 10.1016/S0014-5793(01)02450-4 . 33119468 .
• Fallon L, Moreau F, Croft BG, Labib N, Gu WJ, Fon EA . Parkin and CASK/LIN-2 associate via a PDZ-mediated interaction and are co-localized in lipid rafts and postsynaptic densities in brain . The Journal of Biological Chemistry . 277 . 1 . 486–491 . January 2002 . 11679592 . 10.1074/jbc.M109806200 . free .
• Olsen O, Liu H, Wade JB, Merot J, Welling PA . Basolateral membrane expression of the Kir 2.3 channel is coordinated by PDZ interaction with Lin-7/CASK complex . American Journal of Physiology. Cell Physiology . 282 . 1 . C183–C195 . January 2002 . 11742811 . 10.1152/ajpcell.00249.2001 .

Notes and References

1. Dimitratos SD, Stathakis DG, Nelson CA, Woods DF, Bryant PJ . The location of human CASK at Xp11.4 identifies this gene as a candidate for X-linked optic atrophy . Genomics . 51 . 2 . 308–309 . July 1998 . 9722958 . 10.1006/geno.1998.5404 .
2. Web site: Entrez Gene: CASK Calcium/calmodulin-dependent serine protein kinase (MAGUK family).
3. Tarpey PS, Smith R, Pleasance E, Whibley A, Edkins S, Hardy C, O'Meara S, Latimer C, Dicks E, Menzies A, Stephens P, Blow M, Greenman C, Xue Y, Tyler-Smith C, Thompson D, Gray K, Andrews J, Barthorpe S, Buck G, Cole J, Dunmore R, Jones D, Maddison M, Mironenko T, Turner R, Turrell K, Varian J, West S, Widaa S, Wray P, Teague J, Butler A, Jenkinson A, Jia M, Richardson D, Shepherd R, Wooster R, Tejada MI, Martinez F, Carvill G, Goliath R, de Brouwer AP, van Bokhoven H, Van Esch H, Chelly J, Raynaud M, Ropers HH, Abidi FE, Srivastava AK, Cox J, Luo Y, Mallya U, Moon J, Parnau J, Mohammed S, Tolmie JL, Shoubridge C, Corbett M, Gardner A, Haan E, Rujirabanjerd S, Shaw M, Vandeleur L, Fullston T, Easton DF, Boyle J, Partington M, Hackett A, Field M, Skinner C, Stevenson RE, Bobrow M, Turner G, Schwartz CE, Gecz J, Raymond FL, Futreal PA, Stratton MR . 6 . A systematic, large-scale resequencing screen of X-chromosome coding exons in mental retardation . Nature Genetics . 41 . 5 . 535–543 . May 2009 . 19377476 . 2872007 . 10.1038/ng.367 .
4. Burglen L, Chantot-Bastaraud S, Garel C, Milh M, Touraine R, Zanni G, Petit F, Afenjar A, Goizet C, Barresi S, Coussement A, Ioos C, Lazaro L, Joriot S, Desguerre I, Lacombe D, des Portes V, Bertini E, Siffroi JP, de Villemeur TB, Rodriguez D . 6 . Spectrum of pontocerebellar hypoplasia in 13 girls and boys with CASK mutations: confirmation of a recognizable phenotype and first description of a male mosaic patient . Orphanet Journal of Rare Diseases . 7 . 18 . 18 . March 2012 . 22452838 . 3351739 . 10.1186/1750-1172-7-18 . free .
5. Hackett A, Tarpey PS, Licata A, Cox J, Whibley A, Boyle J, Rogers C, Grigg J, Partington M, Stevenson RE, Tolmie J, Yates JR, Turner G, Wilson M, Futreal AP, Corbett M, Shaw M, Gecz J, Raymond FL, Stratton MR, Schwartz CE, Abidi FE . 6 . CASK mutations are frequent in males and cause X-linked nystagmus and variable XLMR phenotypes . European Journal of Human Genetics . 18 . 5 . 544–552 . May 2010 . 20029458 . 2987321 . 10.1038/ejhg.2009.220 .
6. Becker M, Mastropasqua F, Reising JP, Maier S, Ho ML, Rabkina I, Li D, Neufeld J, Ballenberger L, Myers L, Moritz V, Kele M, Wincent J, Willfors C, Sitnikov R, Herlenius E, Anderlid BM, Falk A, Bölte S, Tammimies K . 6 . Presynaptic dysfunction in CASK-related neurodevelopmental disorders . Translational Psychiatry . 10 . 1 . 312 . September 2020 . 32929080 . 10.1038/s41398-020-00994-0 . 7490425 .
7. Najm J, Horn D, Wimplinger I, Golden JA, Chizhikov VV, Sudi J, Christian SL, Ullmann R, Kuechler A, Haas CA, Flubacher A, Charnas LR, Uyanik G, Frank U, Klopocki E, Dobyns WB, Kutsche K . 6 . Mutations of CASK cause an X-linked brain malformation phenotype with microcephaly and hypoplasia of the brainstem and cerebellum . Nature Genetics . 40 . 9 . 1065–1067 . September 2008 . 19165920 . 10.1038/ng.194 . 91094953 .
8. Moog U, Bierhals T, Brand K, Bautsch J, Biskup S, Brune T, Denecke J, de Die-Smulders CE, Evers C, Hempel M, Henneke M, Yntema H, Menten B, Pietz J, Pfundt R, Schmidtke J, Steinemann D, Stumpel CT, Van Maldergem L, Kutsche K . 6 . Phenotypic and molecular insights into CASK-related disorders in males . Orphanet Journal of Rare Diseases . 10 . 1 . 44 . April 2015 . 25886057 . 4449965 . 10.1186/s13023-015-0256-3 . free .
9. Gafner M, Boltshauser E, D'Abrusco F, Battini R, Romaniello R, D'Arrigo S, Zanni G, Leibovitz Z, Yosovich K, Lerman-Sagie T . 6 . Expanding the natural history of CASK-related disorders to the prenatal period . Developmental Medicine and Child Neurology . September 2022 . 65 . 4 . 544–550 . 36175354 . 10.1111/dmcn.15419 . 252622483 . 11568/1157845 . free .
10. Atasoy D, Schoch S, Ho A, Nadasy KA, Liu X, Zhang W, Mukherjee K, Nosyreva ED, Fernandez-Chacon R, Missler M, Kavalali ET, Südhof TC . 6 . Deletion of CASK in mice is lethal and impairs synaptic function . Proceedings of the National Academy of Sciences of the United States of America . 104 . 7 . 2525–2530 . February 2007 . 17287346 . 1892970 . 10.1073/pnas.0611003104 . 2007PNAS..104.2525A . free .
11. Butz S, Okamoto M, Südhof TC . A tripartite protein complex with the potential to couple synaptic vesicle exocytosis to cell adhesion in brain . English . Cell . 94 . 6 . 773–782 . September 1998 . 9753324 . 10.1016/S0092-8674(00)81736-5 . 12465062 . free .
12. Saitsu H, Kato M, Mizuguchi T, Hamada K, Osaka H, Tohyama J, Uruno K, Kumada S, Nishiyama K, Nishimura A, Okada I, Yoshimura Y, Hirai S, Kumada T, Hayasaka K, Fukuda A, Ogata K, Matsumoto N . 6 . De novo mutations in the gene encoding STXBP1 (MUNC18-1) cause early infantile epileptic encephalopathy . Nature Genetics . 40 . 6 . 782–788 . June 2008 . 18469812 . 10.1038/ng.150 . 1113528 .
13. Mori T, Kasem EA, Suzuki-Kouyama E, Cao X, Li X, Kurihara T, Uemura T, Yanagawa T, Tabuchi K . 6 . Deficiency of calcium/calmodulin-dependent serine protein kinase disrupts the excitatory-inhibitory balance of synapses by down-regulating GluN2B . Molecular Psychiatry . 24 . 7 . 1079–1092 . July 2019 . 30610199 . 10.1038/s41380-018-0338-4 . 6756202 .
14. Leonoudakis D, Conti LR, Anderson S, Radeke CM, McGuire LM, Adams ME, Froehner SC, Yates JR, Vandenberg CA . 6 . Protein trafficking and anchoring complexes revealed by proteomic analysis of inward rectifier potassium channel (Kir2.x)-associated proteins . The Journal of Biological Chemistry . 279 . 21 . 22331–22346 . May 2004 . 15024025 . 10.1074/jbc.M400285200 . free .
15. Leonoudakis D, Conti LR, Radeke CM, McGuire LM, Vandenberg CA . A multiprotein trafficking complex composed of SAP97, CASK, Veli, and Mint1 is associated with inward rectifier Kir2 potassium channels . The Journal of Biological Chemistry . 279 . 18 . 19051–19063 . April 2004 . 14960569 . 10.1074/jbc.M400284200 . free .
16. Borg JP, Lõpez-Figueroa MO, de Taddèo-Borg M, Kroon DE, Turner RS, Watson SJ, Margolis B . Molecular analysis of the X11-mLin-2/CASK complex in brain . The Journal of Neuroscience . 19 . 4 . 1307–1316 . February 1999 . 9952408 . 6786035 . 10.1523/JNEUROSCI.19-04-01307.1999 . free .
17. Schuh K, Uldrijan S, Gambaryan S, Roethlein N, Neyses L . Interaction of the plasma membrane Ca2+ pump 4b/CI with the Ca2+/calmodulin-dependent membrane-associated kinase CASK . The Journal of Biological Chemistry . 278 . 11 . 9778–9783 . March 2003 . 12511555 . 10.1074/jbc.M212507200 . free .
18. Wang GS, Hong CJ, Yen TY, Huang HY, Ou Y, Huang TN, Jung WG, Kuo TY, Sheng M, Wang TF, Hsueh YP . 6 . Transcriptional modification by a CASK-interacting nucleosome assembly protein . Neuron . 42 . 1 . 113–128 . April 2004 . 15066269 . 10.1016/S0896-6273(04)00139-4 . free .
19. Nix SL, Chishti AH, Anderson JM, Walther Z . hCASK and hDlg associate in epithelia, and their src homology 3 and guanylate kinase domains participate in both intramolecular and intermolecular interactions . The Journal of Biological Chemistry . 275 . 52 . 41192–41200 . December 2000 . 10993877 . 10.1074/jbc.M002078200 . free .
20. Chetkovich DM, Bunn RC, Kuo SH, Kawasaki Y, Kohwi M, Bredt DS . Postsynaptic targeting of alternative postsynaptic density-95 isoforms by distinct mechanisms . The Journal of Neuroscience . 22 . 15 . 6415–6425 . August 2002 . 12151521 . 6758133 . 10.1523/JNEUROSCI.22-15-06415.2002 . free .
21. Martinez-Estrada OM, Villa A, Breviario F, Orsenigo F, Dejana E, Bazzoni G . Association of junctional adhesion molecule with calcium/calmodulin-dependent serine protein kinase (CASK/LIN-2) in human epithelial caco-2 cells . The Journal of Biological Chemistry . 276 . 12 . 9291–9296 . March 2001 . 11120739 . 10.1074/jbc.M006991200 . free .
22. Ebnet K, Schulz CU, Meyer Zu Brickwedde MK, Pendl GG, Vestweber D . Junctional adhesion molecule interacts with the PDZ domain-containing proteins AF-6 and ZO-1 . The Journal of Biological Chemistry . 275 . 36 . 27979–27988 . September 2000 . 10856295 . 10.1074/jbc.M002363200 . free.
23. Qi J, Su Y, Sun R, Zhang F, Luo X, Yang Z, Luo X . CASK inhibits ECV304 cell growth and interacts with Id1 . Biochemical and Biophysical Research Communications . 328 . 2 . 517–521 . March 2005 . 15694377 . 10.1016/j.bbrc.2005.01.014 .
24. Borg JP, Straight SW, Kaech SM, de Taddéo-Borg M, Kroon DE, Karnak D, Turner RS, Kim SK, Margolis B . 6 . Identification of an evolutionarily conserved heterotrimeric protein complex involved in protein targeting . The Journal of Biological Chemistry . 273 . 48 . 31633–31636 . November 1998 . 9822620 . 10.1074/jbc.273.48.31633 . free .
25. Lehtonen S, Lehtonen E, Kudlicka K, Holthöfer H, Farquhar MG . Nephrin forms a complex with adherens junction proteins and CASK in podocytes and in Madin-Darby canine kidney cells expressing nephrin . The American Journal of Pathology . 165 . 3 . 923–936 . September 2004 . 15331416 . 1618613 . 10.1016/S0002-9440(10)63354-8 .
26. Fallon L, Moreau F, Croft BG, Labib N, Gu WJ, Fon EA . Parkin and CASK/LIN-2 associate via a PDZ-mediated interaction and are co-localized in lipid rafts and postsynaptic densities in brain . The Journal of Biological Chemistry . 277 . 1 . 486–491 . January 2002 . 11679592 . 10.1074/jbc.M109806200 . free .
27. Zhang Y, Luan Z, Liu A, Hu G . The scaffolding protein CASK mediates the interaction between rabphilin3a and beta-neurexins . FEBS Letters . 497 . 2–3 . 99–102 . May 2001 . 11377421 . 10.1016/S0014-5793(01)02450-4 . 33119468 .
28. Cohen AR, Woods DF, Marfatia SM, Walther Z, Chishti AH, Anderson JM, Wood DF . Human CASK/LIN-2 binds syndecan-2 and protein 4.1 and localizes to the basolateral membrane of epithelial cells . The Journal of Cell Biology . 142 . 1 . 129–138 . July 1998 . 9660868 . 2133028 . 10.1083/jcb.142.1.129 .