Cingulin

Cingulin
Identifiers
Symbols	CGN; DKFZp779N1112; FLJ39281; KIAA1319
External IDs	OMIM: 609473 MGI: 1927237 HomoloGene: 41394 GeneCards: CGN Gene
Gene Ontology Molecular function • motor activity • actin binding • protein binding Cellular component • tight junction • myosin complex • cell junction Biological process • biological_process Sources: Amigo / QuickGO
Orthologs
Species	Human	Mouse
Entrez	57530	70737
Ensembl	ENSG00000143375	ENSMUSG00000068876
UniProt	Q9P2M7	P59242
RefSeq (mRNA)	NM_020770	NM_001037711.2
RefSeq (protein)	NP_065821	NP_001032800.2
Location (UCSC)	Chr 1: 151.48 – 151.51 Mb	Chr 3: 94.46 – 94.59 Mb
PubMed search	[1]	[2]

Cingulin is a protein that in humans is encoded by the CGN gene.^[1][2][3]

Discovery

Cingulin was originally discovered at the MRC Laboratory of Molecular Biology (Cambridge, UK) by Dr. Sandra Citi, as a protein present in chicken intestinal epithelial cells, that co-purified with nonmuscle myosin II, and was specifically localized at tight junctions.^[4]

Structure

Cingulin is a homodimer, each subunit containing a globular "head" domain, a long coiled-coil "rod" domain, and a small globular "tail".^[5] This domain organization is conserved throughout vertebrate species.^[1] However, cingulin homologs have not been detected in invertebrate species.

Function

Cingulin is specifically localized at tight junctions in epithelial cells, unlike ZO-1, which is also detected at adherens-type junctions in non-epithelial cells. During early Xenopus embryo development, cingulin is detected at a cortical localization, and then accumulates at apical junctions, unlike ZO-1 and other junctional proteins, that are targeted to the new regions of cell-cell contact via the lateral domain.^[6][7] Cingulin interacts with ZO-1 and several other tight junction proteins, in addition to interacting with actin and myosin.^[5][8] A conserved sequence in the N-terminal region of cingulin is required for junctional recruitment and interaction with ZO-1. The notion that that ZO-1 recruits cingulin to tight junctions is confirmed by the observation that epithelial cells lacking ZO-1 lose cingulin junctional staining.^[9]

The function of cingulin has been studied by knockout and knockdown approaches. Embryoid bodies derived from embryonic stem cells where one or both cingulin alleles were targeted by homologous recombination show apparently normal tight junctions, but changes in the expression of a large number of genes, including tight junction protein genes (claudin-2, claudin-6, claudin-7 and occludin) and transcription factors (GATA4).^[10] Changes in the expression of claudin-2 and ZO-3 are also observed in cultured kidney cells (MDCK) depleted of cingulin by shRNA.^[11] These effects of cingulin depletion on gene expression are thought to be mediated at least in part by the regulation of RhoA activity by cingulin, snce they can be reversed by dominant-negative RhoA.^[11] Indeed, cingulin interacts with the RhoA exchange factor GEF-H1, and inactivates it by recruiting it to junctions when cells reach confluence.^[12] It was therefore hypothesized that the accumulation of cingulin at mature junctions of confluent monolayers is one mechanism to down-regulate RhoA activity once cells reach confluence. Cells depleted of cingulin also show increased density and proliferation,^[11] indicating that cingulin contributes to regulating cell proliferation. Cingulin is also implicated in the junctional recruitment of the RhoGEF p114RhoGEF, which activates RhoA at tight junctions and is required for junction assembly (Terry et al, Nat. Cell Biol. 2011). Cingulin is expressed in some but not all human carcinomas,^[13] for example its expression is strongly downregulated in epidermoid carcinomas of the lung.^[14] Histone deacetylase inhibitors such as sodium butyrate strongly up-regulate cingulin expression in some cultured cells,^[15] indicating that cingulin is a marker of epithelial differentiation.

Homologs

In 2004, a protein homologous to cingulin was discovered and named JACOP (also known as paracingulin, or cingulin-like 1 protein; CGNL1). Unlike cingulin, paracingulin is detected both at tight and adherens junctions.^[16] The function of paracingulin was clarified when it was discovered that epithelial cells depleted of paracingulin show increased RhoA activation at confluence, and delayed tight junction assembly in the experimental model of the "calcium switch".^[17] The delay in junction assembly correlates with decreased Rac1 activation. In fact, similarly to cingulin, paracingulin contributes to recruiting and inactivating the RhoA guanine exchange factor GEF-H1 to junctions. In addition, paracingulin interacts with and recruits to junctions the Rac1 guanine exchange factor Tiam1.^[17]

References

1. ^ ^{a b} Citi S, D'Atri F, Parry DA (August 2000). "Human and Xenopus cingulin share a modular organization of the coiled-coil rod domain: predictions for intra- and intermolecular assembly". J. Struct. Biol. 131 (2): 135–45. doi:10.1006/jsbi.2000.4284. PMID 11042084. 
2. ^ Nagase T, Kikuno R, Ishikawa KI, Hirosawa M, Ohara O (February 2000). "Prediction of the coding sequences of unidentified human genes. XVI. The complete sequences of 150 new cDNA clones from brain which code for large proteins in vitro". DNA Res. 7 (1): 65–73. doi:10.1093/dnares/7.1.65. PMID 10718198. 
3. ^ "Entrez Gene: CGN cingulin". http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=57530. 
4. ^ Citi S, Sabanay H, Jakes R, Geiger B, Kendrick-Jones J (May 1988). "Cingulin, a new peripheral component of tight junctions". Nature 333 (6170): 272–6. doi:10.1038/333272a0. PMID 3285223. 
5. ^ ^{a b} Cordenonsi M, D'Atri F, Hammar E, Parry DA, Kendrick-Jones J, Shore D, Citi S (December 1999). "Cingulin contains globular and coiled-coil domains and interacts with ZO-1, ZO-2, ZO-3, and myosin". J. Cell Biol. 147 (7): 1569–82. doi:10.1083/jcb.147.7.1569. PMC 2174252. PMID 10613913. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2174252. 
6. ^ Cardellini P, Davanzo G, Citi S (September 1996). "Tight junctions in early amphibian development: detection of junctional cingulin from the 2-cell stage and its localization at the boundary of distinct membrane domains in dividing blastomeres in low calcium". Dev. Dyn. 207 (1): 104–13. doi:10.1002/(SICI)1097-0177(199609)207:1<104::AID-AJA10>3.0.CO;2-0. PMID 8875080. 
7. ^ Fesenko I, Kurth T, Sheth B, Fleming TP, Citi S, Hausen P (August 2000). "Tight junction biogenesis in the early Xenopus embryo". Mech. Dev. 96 (1): 51–65. doi:10.1016/S0925-4773(00)00368-3. PMID 10940624. 
8. ^ D'Atri F, Citi S (October 2001). "Cingulin interacts with F-actin in vitro". FEBS Lett. 507 (1): 21–4. doi:10.1016/S0014-5793(01)02936-2. PMID 11682052. 
9. ^ Umeda K, Matsui T, Nakayama M, Furuse K, Sasaki H, Furuse M, Tsukita S (October 2004). "Establishment and characterization of cultured epithelial cells lacking expression of ZO-1". J. Biol. Chem. 279 (43): 44785–94. doi:10.1074/jbc.M406563200. PMID 15292177. 
10. ^ Guillemot L, Hammar E, Kaister C, Ritz J, Caille D, Jond L, Bauer C, Meda P, Citi S (October 2004). "Disruption of the cingulin gene does not prevent tight junction formation but alters gene expression". J. Cell. Sci. 117 (Pt 22): 5245–56. doi:10.1242/jcs.01399. PMID 15454572. 
11. ^ ^{a b c} Guillemot L, Citi S (August 2006). "Cingulin regulates claudin-2 expression and cell proliferation through the small GTPase RhoA". Mol. Biol. Cell 17 (8): 3569–77. doi:10.1091/mbc.E06-02-0122. PMC 1525245. PMID 16723500. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1525245. 
12. ^ Aijaz S, D'Atri F, Citi S, Balda MS, Matter K (May 2005). "Binding of GEF-H1 to the tight junction-associated adaptor cingulin results in inhibition of Rho signaling and G1/S phase transition". Dev. Cell 8 (5): 777–86. doi:10.1016/j.devcel.2005.03.003. PMID 15866167. 
13. ^ Citi S, Amorosi A, Franconi F, Giotti A, Zampi G (April 1991). "Cingulin, a specific protein component of tight junctions, is expressed in normal and neoplastic human epithelial tissues". Am. J. Pathol. 138 (4): 781–9. PMC 1886117. PMID 2012170. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1886117. 
14. ^ Paschoud S, Bongiovanni M, Pache JC, Citi S (September 2007). "Claudin-1 and claudin-5 expression patterns differentiate lung squamous cell carcinomas from adenocarcinomas". Mod. Pathol. 20 (9): 947–54. doi:10.1038/modpathol.3800835. PMID 17585317. 
15. ^ Bordin M, D'Atri F, Guillemot L, Citi S (December 2004). "Histone deacetylase inhibitors up-regulate the expression of tight junction proteins". Mol. Cancer Res. 2 (12): 692–701. PMID 15634758. 
16. ^ Ohnishi H, Nakahara T, Furuse K, Sasaki H, Tsukita S, Furuse M (October 2004). "JACOP, a novel plaque protein localizing at the apical junctional complex with sequence similarity to cingulin". J. Biol. Chem. 279 (44): 46014–22. doi:10.1074/jbc.M402616200. PMID 15292197. 
17. ^ ^{a b} Guillemot L, Paschoud S, Jond L, Foglia A, Citi S (October 2008). "Paracingulin regulates the activity of Rac1 and RhoA GTPases by recruiting Tiam1 and GEF-H1 to epithelial junctions". Mol. Biol. Cell 19 (10): 4442–53. doi:10.1091/mbc.E08-06-0558. PMC 2555940. PMID 18653465. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2555940. 

Further reading

• Wolburg H, Lippoldt A (2003). "Tight junctions of the blood-brain barrier: development, composition and regulation.". Vascul. Pharmacol. 38 (6): 323–37. doi:10.1016/S1537-1891(02)00200-8. PMID 12529927. 
• Bazzoni G, Martinez-Estrada OM, Orsenigo F, et al. (2000). "Interaction of junctional adhesion molecule with the tight junction components ZO-1, cingulin, and occludin.". J. Biol. Chem. 275 (27): 20520–6. doi:10.1074/jbc.M905251199. PMID 10877843. 
• D'Atri F, Nadalutti F, Citi S (2002). "Evidence for a functional interaction between cingulin and ZO-1 in cultured cells.". J. Biol. Chem. 277 (31): 27757–64. doi:10.1074/jbc.M203717200. PMID 12023291. 
• Strausberg RL, Feingold EA, Grouse LH, et al. (2003). "Generation and initial analysis of more than 15,000 full-length human and mouse cDNA sequences.". Proc. Natl. Acad. Sci. U.S.A. 99 (26): 16899–903. doi:10.1073/pnas.242603899. PMC 139241. PMID 12477932. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=139241. 
• Gevaert K, Goethals M, Martens L, et al. (2004). "Exploring proteomes and analyzing protein processing by mass spectrometric identification of sorted N-terminal peptides.". Nat. Biotechnol. 21 (5): 566–9. doi:10.1038/nbt810. PMID 12665801. 
• Ota T, Suzuki Y, Nishikawa T, et al. (2004). "Complete sequencing and characterization of 21,243 full-length human cDNAs.". Nat. Genet. 36 (1): 40–5. doi:10.1038/ng1285. PMID 14702039. 
• Jin J, Smith FD, Stark C, et al. (2004). "Proteomic, functional, and domain-based analysis of in vivo 14-3-3 binding proteins involved in cytoskeletal regulation and cellular organization.". Curr. Biol. 14 (16): 1436–50. doi:10.1016/j.cub.2004.07.051. PMID 15324660. 
• Benzinger A, Muster N, Koch HB, et al. (2005). "Targeted proteomic analysis of 14-3-3 sigma, a p53 effector commonly silenced in cancer.". Mol. Cell Proteomics 4 (6): 785–95. doi:10.1074/mcp.M500021-MCP200. PMID 15778465. 
• Aijaz S, D'Atri F, Citi S, et al. (2005). "Binding of GEF-H1 to the tight junction-associated adaptor cingulin results in inhibition of Rho signaling and G1/S phase transition.". Dev. Cell 8 (5): 777–86. doi:10.1016/j.devcel.2005.03.003. PMID 15866167. 
• Kim JE, Tannenbaum SR, White FM (2005). "Global phosphoproteome of HT-29 human colon adenocarcinoma cells.". J. Proteome Res. 4 (4): 1339–46. doi:10.1021/pr050048h. PMID 16083285. 
• Gregory SG, Barlow KF, McLay KE, et al. (2006). "The DNA sequence and biological annotation of human chromosome 1.". Nature 441 (7091): 315–21. doi:10.1038/nature04727. PMID 16710414. 
• Ewing RM, Chu P, Elisma F, et al. (2007). "Large-scale mapping of human protein-protein interactions by mass spectrometry.". Mol. Syst. Biol. 3 (1): 89. doi:10.1038/msb4100134. PMC 1847948. PMID 17353931. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1847948.