{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,28]],"date-time":"2026-01-28T13:26:52Z","timestamp":1769606812376,"version":"3.49.0"},"reference-count":52,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2020,4,11]],"date-time":"2020-04-11T00:00:00Z","timestamp":1586563200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000002","name":"National Institutes of Health","doi-asserted-by":"publisher","award":["R01DK107764"],"award-info":[{"award-number":["R01DK107764"]}],"id":[{"id":"10.13039\/100000002","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Cells"],"abstract":"<jats:p>Congenital tufting enteropathy (CTE) is a rare chronic diarrheal disease of infancy caused by mutations in epithelial cell adhesion molecule (EpCAM). Previously, a murine CTE model showed mis-localization of EpCAM away from the basolateral cell surface in the intestine. Here we demonstrate that mutant EpCAM accumulated in the endoplasmic reticulum (ER) where it co-localized with ER chaperone, GRP78\/BiP, revealing potential involvement of ER stress-induced unfolded protein response (UPR) pathway in CTE. To investigate the significance of ER-localized mutant EpCAM in CTE, activation of the three UPR signaling branches initiated by the ER transmembrane protein components IRE1, PERK, and ATF6 was tested. A significant reduction in BLOS1 and SCARA3 mRNA levels in EpCAM mutant intestinal cells demonstrated that regulated IRE1-dependent decay (RIDD) was activated. However, IRE1 dependent XBP1 mRNA splicing was not induced. Furthermore, an increase in nuclear-localized ATF6 in mutant intestinal tissues revealed activation of the ATF6-signaling arm. Finally, an increase in both the phosphorylated form of the translation initiation factor, eIF2\u03b1, and ATF4 expression in the mutant intestine provided support for activation of the PERK-mediated pathway. Our results are consistent with a significant role for UPR in gastrointestinal homeostasis and provide a working model for CTE pathophysiology.<\/jats:p>","DOI":"10.3390\/cells9040946","type":"journal-article","created":{"date-parts":[[2020,4,14]],"date-time":"2020-04-14T03:10:01Z","timestamp":1586833801000},"page":"946","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":8,"title":["Congenital Tufting Enteropathy-Associated Mutant of Epithelial Cell Adhesion Molecule Activates the Unfolded Protein Response in a Murine Model of the Disease"],"prefix":"10.3390","volume":"9","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-4669-8550","authenticated-orcid":false,"given":"Barun","family":"Das","sequence":"first","affiliation":[{"name":"Department of Pediatrics, University of California, San Diego, CA 92093, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kevin","family":"Okamoto","sequence":"additional","affiliation":[{"name":"Department of Pediatrics, University of California, San Diego, CA 92093, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"John","family":"Rabalais","sequence":"additional","affiliation":[{"name":"Department of Pediatrics, University of California, San Diego, CA 92093, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ronald R.","family":"Marchelletta","sequence":"additional","affiliation":[{"name":"Department of Medicine, University of California, San Diego, CA 92093, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kim E.","family":"Barrett","sequence":"additional","affiliation":[{"name":"Department of Medicine, University of California, San Diego, CA 92093, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Soumita","family":"Das","sequence":"additional","affiliation":[{"name":"Department of Pathology, University of California, San Diego, CA 92093, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3540-6249","authenticated-orcid":false,"given":"Maho","family":"Niwa","sequence":"additional","affiliation":[{"name":"Division of Biological Sciences, University of California, San Diego, CA 92093, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3643-1326","authenticated-orcid":false,"given":"Mamata","family":"Sivagnanam","sequence":"additional","affiliation":[{"name":"Department of Pediatrics, University of California, San Diego, CA 92093, USA"},{"name":"Rady Children\u2019s Hospital, San Diego, CA 92123, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2020,4,11]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"20","DOI":"10.1186\/1750-1172-2-20","article-title":"Intestinal epithelial dysplasia (tufting enteropathy)","volume":"2","author":"Goulet","year":"2007","journal-title":"Orphanet J. Rare Dis."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"379","DOI":"10.1002\/j.1536-4801.1994.tb11192.x","article-title":"Tufting enteropathy: A newly recognized clinicopathological entity associated with refractory diarrhea in infants","volume":"18","author":"Reifen","year":"1994","journal-title":"J. Pediatr. Gastroenterol. Nutr."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"429","DOI":"10.1053\/j.gastro.2008.05.036","article-title":"Identification of EpCAM as the gene for congenital tufting enteropathy","volume":"135","author":"Sivagnanam","year":"2008","journal-title":"Gastroenterology"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"699","DOI":"10.1007\/s001099900038","article-title":"The biology of the 17-1A antigen (Ep-CAM)","volume":"77","author":"Balzar","year":"1999","journal-title":"J. Mol. Med. (Berl.)"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"386","DOI":"10.2353\/ajpath.2007.070152","article-title":"Epithelial cell adhesion molecule: More than a carcinoma marker and adhesion molecule","volume":"171","author":"Trzpis","year":"2007","journal-title":"Am. J. Pathol."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"142","DOI":"10.1002\/humu.23688","article-title":"EPCAM mutation update: Variants associated with congenital tufting enteropathy and Lynch syndrome","volume":"40","author":"Pathak","year":"2019","journal-title":"Hum. Mutat."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"2566","DOI":"10.1093\/hmg\/ddt105","article-title":"Absence of cell-surface EpCAM in congenital tufting enteropathy","volume":"22","author":"Schnell","year":"2013","journal-title":"Hum. Mol. Genet."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"4764","DOI":"10.1038\/ncomms5764","article-title":"Crystal structure and its bearing towards an understanding of key biological functions of EpCAM","volume":"5","author":"Pavsic","year":"2014","journal-title":"Nat. Commun."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"G278","DOI":"10.1152\/ajpgi.00286.2013","article-title":"Functional consequences of EpCam mutation in mice and men","volume":"306","author":"Mueller","year":"2014","journal-title":"Am. J. Physiol. Gastrointest. Liver Physiol."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"e00030","DOI":"10.1042\/BSR20120128","article-title":"EpCAM proteolysis: New fragments with distinct functions?","volume":"33","author":"Schnell","year":"2013","journal-title":"Biosci. Rep."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"315","DOI":"10.1038\/sj.emboj.7601974","article-title":"Protein quality control in the early secretory pathway","volume":"27","author":"Anelli","year":"2008","journal-title":"EMBO J."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"944","DOI":"10.1126\/science.1146361","article-title":"IRE1 signaling affects cell fate during the unfolded protein response","volume":"318","author":"Lin","year":"2007","journal-title":"Science"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"169","DOI":"10.1016\/j.molcel.2017.06.017","article-title":"The Unfolded Protein Response and Cell Fate Control","volume":"69","author":"Hetz","year":"2018","journal-title":"Mol. Cell"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"239","DOI":"10.1016\/j.ceb.2011.01.003","article-title":"Protein folding stress in neurodegenerative diseases: A glimpse into the ER","volume":"23","author":"Matus","year":"2011","journal-title":"Curr. Opin. Cell Biol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"317","DOI":"10.1146\/annurev-med-043010-144749","article-title":"Role of endoplasmic reticulum stress in metabolic disease and other disorders","volume":"63","author":"Ozcan","year":"2012","journal-title":"Annu. Rev. Med."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"5467","DOI":"10.4049\/jimmunol.1103661","article-title":"Atypical activation of the unfolded protein response in cystic fibrosis airway cells contributes to p38 MAPK-mediated innate immune responses","volume":"189","author":"Blohmke","year":"2012","journal-title":"J. Immunol."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"156","DOI":"10.1016\/j.smim.2009.01.001","article-title":"Endoplasmic reticulum stress in the intestinal epithelium and inflammatory bowel disease","volume":"21","author":"Kaser","year":"2009","journal-title":"Semin. Immunol."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"788","DOI":"10.1016\/j.dld.2014.05.013","article-title":"Endoplasmic reticulum stress and unfolded protein response are involved in paediatric inflammatory bowel disease","volume":"46","author":"Negroni","year":"2014","journal-title":"Dig. Liver Dis."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"7448","DOI":"10.1128\/MCB.23.21.7448-7459.2003","article-title":"XBP-1 regulates a subset of endoplasmic reticulum resident chaperone genes in the unfolded protein response","volume":"23","author":"Lee","year":"2003","journal-title":"Mol. Cell Biol."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"323","DOI":"10.1083\/jcb.200903014","article-title":"Regulated Ire1-dependent decay of messenger RNAs in mammalian cells","volume":"186","author":"Hollien","year":"2009","journal-title":"J. Cell Biol."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"271","DOI":"10.1038\/16729","article-title":"Protein translation and folding are coupled by an endoplasmic-reticulum-resident kinase","volume":"397","author":"Harding","year":"1999","journal-title":"Nature"},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Rutkowski, D.T., Arnold, S.M., Miller, C.N., Wu, J., Li, J., Gunnison, K.M., Mori, K., Sadighi Akha, A.A., Raden, D., and Kaufman, R.J. (2006). Adaptation to ER stress is mediated by differential stabilities of pro-survival and pro-apoptotic mRNAs and proteins. PLoS Biol., 4.","DOI":"10.1371\/journal.pbio.0040374"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"13045","DOI":"10.1074\/jbc.M110636200","article-title":"The luminal domain of ATF6 senses endoplasmic reticulum (ER) stress and causes translocation of ATF6 from the ER to the Golgi","volume":"277","author":"Chen","year":"2002","journal-title":"J. Biol. Chem."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"3787","DOI":"10.1091\/mbc.10.11.3787","article-title":"Mammalian transcription factor ATF6 is synthesized as a transmembrane protein and activated by proteolysis in response to endoplasmic reticulum stress","volume":"10","author":"Haze","year":"1999","journal-title":"Mol. Biol. Cell"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"535","DOI":"10.1007\/s00109-014-1239-x","article-title":"Mutation of EpCAM leads to intestinal barrier and ion transport dysfunction","volume":"93","author":"Kozan","year":"2015","journal-title":"J. Mol. Med."},{"key":"ref_26","first-page":"G204","article-title":"A human colonic tumor cell line that maintains vectorial electrolyte transport","volume":"246","author":"Dharmsathaphorn","year":"1984","journal-title":"Am. J. Physiol."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"115","DOI":"10.1007\/978-1-61779-191-8_8","article-title":"Studying permeability in a commonly used epithelial cell line: T84 intestinal epithelial cells","volume":"763","author":"Donato","year":"2011","journal-title":"Methods Mol. Biol."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"75","DOI":"10.1016\/j.fct.2016.04.003","article-title":"An experimental platform using human intestinal epithelial cell lines to differentiate between hazardous and non-hazardous proteins","volume":"92","author":"Hurley","year":"2016","journal-title":"Food Chem. Toxicol."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"850","DOI":"10.1016\/j.celrep.2014.09.016","article-title":"Ire1 has distinct catalytic mechanisms for XBP1\/HAC1 splicing and RIDD","volume":"9","author":"Tam","year":"2014","journal-title":"Cell Rep."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"e00211","DOI":"10.1002\/prp2.211","article-title":"Role of endoplasmic reticulum stress in drug-induced toxicity","volume":"4","author":"Foufelle","year":"2016","journal-title":"Pharmacol. Res. Perspect."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"E869","DOI":"10.1073\/pnas.1115623109","article-title":"The molecular basis for selective inhibition of unconventional mRNA splicing by an IRE1-binding small molecule","volume":"109","author":"Cross","year":"2012","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"C723","DOI":"10.1152\/ajpcell.00462.2010","article-title":"A practical guide to evaluating colocalization in biological microscopy","volume":"300","author":"Dunn","year":"2011","journal-title":"Am. J. Physiol. Cell Physiol."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"30873","DOI":"10.1074\/jbc.272.49.30873","article-title":"BiP, a major chaperone protein of the endoplasmic reticulum lumen, plays a direct and important role in the storage of the rapidly exchanging pool of Ca2+","volume":"272","author":"Lievremont","year":"1997","journal-title":"J. Biol. Chem."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"92","DOI":"10.1038\/415092a","article-title":"IRE1 couples endoplasmic reticulum load to secretory capacity by processing the XBP-1 mRNA","volume":"415","author":"Calfon","year":"2002","journal-title":"Nature"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"3119","DOI":"10.1093\/emboj\/18.11.3119","article-title":"Mechanism of non-spliceosomal mRNA splicing in the unfolded protein response pathway","volume":"18","author":"Gonzalez","year":"1999","journal-title":"EMBO J."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"306","DOI":"10.3390\/genes4030306","article-title":"Signaling pathways from the endoplasmic reticulum and their roles in disease","volume":"4","author":"Kadowaki","year":"2013","journal-title":"Genes (Basel)"},{"key":"ref_37","doi-asserted-by":"crossref","unstructured":"Szabo, R., Callies, L.K., and Bugge, T.H. (2019). Matriptase drives early-onset intestinal failure in a mouse model of congenital tufting enteropathy. Development, 146.","DOI":"10.1242\/dev.183392"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"623","DOI":"10.1172\/JCI88428","article-title":"Matriptase-mediated cleavage of EpCAM destabilizes claudins and dysregulates intestinal epithelial homeostasis","volume":"127","author":"Wu","year":"2017","journal-title":"J. Clin. Investig."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"525","DOI":"10.1083\/jcb.200907074","article-title":"Membrane expansion alleviates endoplasmic reticulum stress independently of the unfolded protein response","volume":"187","author":"Schuck","year":"2009","journal-title":"J. Cell Biol."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"G580","DOI":"10.1152\/ajpgi.00098.2019","article-title":"Enteroids expressing a disease-associated mutant of EpCAM are a model for congenital tufting enteropathy","volume":"317","author":"Das","year":"2019","journal-title":"Am. J. Physiol. Gastrointest. Liver Physiol."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"104","DOI":"10.1126\/science.1129631","article-title":"Decay of endoplasmic reticulum-localized mRNAs during the unfolded protein response","volume":"313","author":"Hollien","year":"2006","journal-title":"Science"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"71","DOI":"10.1099\/vir.0.057265-0","article-title":"Regulated IRE1-dependent decay pathway is activated during Japanese encephalitis virus-induced unfolded protein response and benefits viral replication","volume":"95","author":"Bhattacharyya","year":"2014","journal-title":"J. Gen. Virol."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"76","DOI":"10.3389\/fgene.2014.00076","article-title":"Physiological roles of regulated Ire1 dependent decay","volume":"5","author":"Coelho","year":"2014","journal-title":"Front. Genet."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"245","DOI":"10.1016\/j.tibs.2014.02.008","article-title":"Getting RIDD of RNA. IRE1 in cell fate regulation","volume":"39","author":"Maurel","year":"2014","journal-title":"Trends Biochem. Sci."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"e26845","DOI":"10.7554\/eLife.26845","article-title":"Unfolded protein response transducer IRE1-mediated signaling independent of XBP1 mRNA splicing is not required for growth and development of medaka fish","volume":"6","author":"Ishikawa","year":"2017","journal-title":"Elife"},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"585","DOI":"10.1172\/JCI11476","article-title":"Increased sensitivity to dextran sodium sulfate colitis in IRE1beta-deficient mice","volume":"107","author":"Bertolotti","year":"2001","journal-title":"J. Clin. Investig."},{"key":"ref_47","doi-asserted-by":"crossref","unstructured":"Grey, M.J., Cloots, E., Simpson, M.S., LeDuc, N., Serebrenik, Y.V., De Luca, H., De Sutter, D., Luong, P., Thiagarajah, J.R., and Paton, A.W. (2020). IRE1beta negatively regulates IRE1alpha signaling in response to endoplasmic reticulum stress. J. Cell Biol., 219.","DOI":"10.1083\/jcb.201904048"},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"318","DOI":"10.1038\/nrm1618","article-title":"Translational control in stress and apoptosis","volume":"6","author":"Holcik","year":"2005","journal-title":"Nat. Rev. Mol. Cell Biol."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"327","DOI":"10.1016\/j.devcel.2018.04.023","article-title":"The UPR Activator ATF6 Responds to Proteotoxic and Lipotoxic Stress by Distinct Mechanisms","volume":"46","author":"Tam","year":"2018","journal-title":"Dev. Cell"},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"652","DOI":"10.1111\/j.1460-9568.2012.08008.x","article-title":"The unfolded protein response in models of human mutant G93A amyotrophic lateral sclerosis","volume":"35","author":"Prell","year":"2012","journal-title":"Eur. J. Neurosci."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"223","DOI":"10.1007\/978-3-319-17121-0_30","article-title":"TULP1 Missense Mutations Induces the Endoplasmic Reticulum Unfolded Protein Response Stress Complex (ER-UPR)","volume":"854","author":"Lobo","year":"2016","journal-title":"Adv. Exp. Med. Biol."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"3001","DOI":"10.1523\/JNEUROSCI.3678-14.2015","article-title":"Loss of Clcc1 results in ER stress, misfolded protein accumulation, and neurodegeneration","volume":"35","author":"Jia","year":"2015","journal-title":"J. Neurosci."}],"container-title":["Cells"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2073-4409\/9\/4\/946\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,13]],"date-time":"2025-10-13T13:21:00Z","timestamp":1760361660000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2073-4409\/9\/4\/946"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2020,4,11]]},"references-count":52,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2020,4]]}},"alternative-id":["cells9040946"],"URL":"https:\/\/doi.org\/10.3390\/cells9040946","relation":{},"ISSN":["2073-4409"],"issn-type":[{"value":"2073-4409","type":"electronic"}],"subject":[],"published":{"date-parts":[[2020,4,11]]}}}