Glycobiology Advance Access published online on October 31, 2007
Glycobiology, doi:10.1093/glycob/cwm118
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Identification and expression of human epiglycanin/MUC21: a novel transmembrane mucin
* Laboratory of Cancer Biology and Molecular Immunology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan
|| Department of Molecular Preventive Medicine, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan
¶ Department of Pathology, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan
1 All correspondence should be addressed to Tatsuro Irimura, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Telephone +81-3-5841-4870, Fax +81-3-5841-4879, e-mail irimura{at}mol.f.u-tokyo.ac.jp.
Received on July 31, 2007; accepted on October 15, 2007
The gene for the human orthologue of mouse epiglycanin, a mucin expressed on mammary carcinoma TA3-Ha cells but not TA3-St cells, was identified by homology search to a mouse epiglycanin cDNA fragment identified by representational difference analysis between TA3-Ha and TA3-St cells. The open reading frame of this gene was cloned from human cervical carcinoma ME-180 cells. It consists of a mucin domain with 28 non-identical tandem repeats of 45 nucleotides each corresponding to a threonine/serine-rich peptide, a stem domain, a transmembrane domain, and a cytoplasmic tail. The cloned cDNA with a FLAG sequence was expressed in K562 cells. A combination of immunoprecipitation with a polyclonal antibody specific for the cytoplasmic tail and Western blotting analysis with anti-FLAG antibody and lectins revealed a mucin-like component as the gene product. Analysis by the use of tissue cDNA libraries indicated that the gene is expressed in lung, large intestine, thymus, and testis among 16 normal tissues tested. The polyclonal antibody specific for a synthetic peptide from the cytoplasmic tail, when tested for its reactivity with normal lung tissues, reacted with epithelia of bronchi and bronchioli but not with alveoli. All of 24 lung adenocarcinomas specimens tested were reactive with the antibody, whereas reactivity was observed with only 2 out of 24 squamous and none out of 24 small cell lung carcinomas. This is a novel transmembrane mucin and designated as MUC21.
Key words: Mucin / epiglycanin / cDNA cloning / lung carcinoma
These authors equally contributed to this work. The nucleotide sequences reported in this paper have been submitted to the DDBJ/GenBank/EBI Deta Bank with the accession numbers AB242595 for human epiglycanin/MUC21 cDNA and AB242596 for mouse epiglycanin/Muc21 cDNA.