Calcium and pH-dependent packing and release of the gel-forming MUC2 mucin
2012 (English)In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 109, no 15, 5645-5650 p.Article in journal (Refereed) Published
MUC2, the major colonic mucin, forms large polymers by N-terminal trimerization and C-terminal dimerization. Although the assembly process for MUC2 is established, it is not known how MUC2 is packed in the regulated secretory granulae of the goblet cell. When the N-terminal VWD1-D2-D'D3 domains (MUC2-N) were expressed in a goblet-like cell line, the protein was stored together with full-length MUC2. By mimicking the pH and calcium conditions of the secretory pathway we analyzed purified MUC2-N by gel filtration, density gradient centrifugation, and transmission electron microscopy. At pH 7.4 the MUC2-N trimer eluted as a single peak by gel filtration. At pH 6.2 with Ca2+ it formed large aggregates that did not enter the gel filtration column but were made visible after density gradient centrifugation. Electron microscopy studies revealed that the aggregates were composed of rings also observed in secretory granulae of colon tissue sections. TheMUC2-N aggregates were dissolved by removing Ca2+ and raising pH. After release from goblet cells, the unfolded full-length MUC2 formed stratified layers. These findings suggest a model for mucin packing in the granulae and the mechanism for mucin release, unfolding, and expansion.
Place, publisher, year, edition, pages
National Academy of Sciences , 2012. Vol. 109, no 15, 5645-5650 p.
mucus, bicarbonate, cystic fibrosis, unpacking
IdentifiersURN: urn:nbn:se:kth:diva-87839DOI: 10.1073/pnas.1120269109ISI: 000302533500025ScopusID: 2-s2.0-84859613830OAI: oai:DiVA.org:kth-87839DiVA: diva2:501946
FunderSwedish Research Council, 7461 21027Knut and Alice Wallenberg Foundation
QC 20120507. Updated from manuscript to article in journal2012-02-142012-02-142016-04-25Bibliographically approved