Hodgkin's lymphoma cell lines express a fusion protein encoded by intergenically spliced mRNA for the multilectin receptor DEC-205 (CD205) and a novel C-type lectin receptor DCL-1.
Classic Hodgkin's lymphoma (HL) tissue contains a small population of morphologically distinct malignant cells called Hodgkin and Reed-Sternberg (HRS) cells, associated with the development of HL. Using 3'-rapid amplification of cDNA ends (RACE) we identified an alternative mRNA for the DEC-205 multilectin receptor in the HRS cell line L428. Sequence analysis revealed that the mRNA encodes a fusion protein between DEC-205 and a novel C-type lectin DCL-1. Although the 7.5-kb DEC-205 and 4.2-kb DCL-1 mRNA were expressed independently in myeloid and B lymphoid cell lines, the DEC-205/DCL-1 fusion mRNA (9.5 kb) predominated in the HRS cell lines (L428, KM-H2, and HDLM-2). The DEC-205 and DCL-1 genes comprising 35 and 6 exons, respectively, are juxtaposed on chromosome band 2q24 and separated by only 5.4 kb. We determined the DCL-1 transcription initiation site within the intervening sequence by 5'-RACE, confirming that DCL-1 is an independent gene. Two DEC-205/DCL-1 fusion mRNA variants may result from cotranscription of DEC-205 and DCL-1, followed by splicing DEC-205 exon 35 or 34-35 along with DCL-1 exon 1. The resulting reading frames encode the DEC-205 ectodomain plus the DCL-1 ectodomain, the transmembrane, and the cytoplasmic domain. Using DCL-1 cytoplasmic domain-specific polyclonal and DEC-205 monoclonal antibodies for immunoprecipitation/Western blot analysis, we showed that the fusion mRNA is translated into a DEC-205/DCL-1 fusion protein, expressed in the HRS cell lines. These results imply an unusual transcriptional control mechanism in HRS cells, which cotranscribe an mRNA containing DEC-205 and DCL-1 prior to generating the intergenically spliced mRNA to produce a DEC-205/DCL-1 fusion protein.
Kato
Masato
M
Mater Medical Research Institute, Aubigny Place, Raymond Terrace, South Brisbane, Queensland 4101, Australia. mkato@mmri.mater.org.au
Khan
Seema
S
Gonzalez
Nelson
N
O'Neill
Brian P
BP
McDonald
Kylie J
KJ
Cooper
Ben J
BJ
Angel
Nicola Z
NZ
Hart
Derek N J
DN
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D015703:Antigens, CD / Q000737:chemistry*; D001483:Base Sequence; D015152:Blotting, Northern; D015153:Blotting, Western; D002460:Cell Line; D002875:Chromosomes / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005091:Exons; D018922:HL-60 Cells; D006689:Hodgkin Disease / Q000378:metabolism*; D006801:Humans; D019169:Jurkat Cells; D037102:Lectins / Q000378:metabolism; D037181:Lectins, C-Type / Q000737:chemistry*; D015778:Minor Histocompatibility Antigens; D008957:Models, Genetic; D008969:Molecular Sequence Data; D015514:Oncogene Proteins, Fusion / Q000737:chemistry* / Q000378:metabolism*; D011233:Precipitin Tests; D017434:Protein Structure, Tertiary; D012326:RNA Splicing; D012333:RNA, Messenger / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000737:chemistry* / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
D015703:Antigens, CD; C477741:CD302 protein, human; C093569:DEC-205 receptor; D018076:DNA, Complementary; C477754:LY75-CD302 readthrough, human; D037102:Lectins; D037181:Lectins, C-Type; D015778:Minor Histocompatibility Antigens; D015514:Oncogene Proteins, Fusion; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins