Secreted CEACAM1 splice variants in rat cell lines and in vivo in rat serum.
The widely expressed adhesion receptor CEACAM1 is a member of the carcinoembryonic antigen (CEA) family within the immunoglobulin (Ig) superfamily of glycoproteins. While the expression of transmembrane isoforms has been described in detail, only little is known about soluble isoforms. By RT-PCR characterization of rat pheochromocytoma PC12 and mammary adenocarcinoma MTC cell lines, two novel splice variants, designated CEACAM1-4C1 and CEACAM1-4C2, lacking the transmembrane region, were identified. In addition, we demonstrate the expression of transmembrane CEACAM1-4L and CEACAM1-4S with a truncated cytoplasmic domain. The C-termini of CEACAM1-4C2 and CEACAM1-L are identical, which allowed the specific in vitro and in vivo detection of the soluble CEACAM1-4C2 protein by an antiserum generated against the CEACAM1-L cytoplasmic part. Functionally, soluble CEACAM1 could inhibit CEACAM1-mediated aggregation of CHO cells. In conclusion, our data define a new mechanism for the appearance of functionally active rat CEACAM1 protein in body fluids.
Budt
Matthias
M
Institut für Molekularbiologie und Biochemie, Universitätsklinikum Benjamin Franklin, Freie Universität Berlin, Arnimallee 22, D-14195 Berlin-Dahlem, Germany.
Michely
Beate
B
Müller
Mario M
MM
Reutter
Werner
W
Lucka
Lothar
L
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD / Q000097:blood* / Q000737:chemistry / Q000235:genetics*; D000943:Antigens, Differentiation / Q000097:blood* / Q000737:chemistry / Q000235:genetics*; D015815:Cell Adhesion Molecules / Q000097:blood* / Q000737:chemistry / Q000235:genetics*; D016895:Culture Media, Serum-Free; D008969:Molecular Sequence Data; D020033:Protein Isoforms; D051381:Rats; D011915:Rats, Inbred BUF; D016415:Sequence Alignment; D014407:Tumor Cells, Cultured
D015703:Antigens, CD; D000943:Antigens, Differentiation; C069847:CD66 antigens; D015815:Cell Adhesion Molecules; D016895:Culture Media, Serum-Free; D020033:Protein Isoforms