Identification of HLA-G7 as a new splice variant of the HLA-G mRNA and expression of soluble HLA-G5, -G6, and -G7 transcripts in human transfected cells.
The nonclassical HLA-G primary transcript is alternatively spliced to generate several mRNAs that have the capacity to encode four membrane bound isoforms, namely HLA-G1, -G2, -G3, and -G4 and two soluble isoforms HLA-G5 and -G6. We aimed at defining the capacity of full length and truncated soluble HLA-G transcripts to be translated in human cell lines. Our study of HLA-G alternative transcripts in various human tissues led us to identify a new splice variant of the HLA-G mRNA, named G7, in which open reading frame continues in intron 2. Due to the presence of a stop codon within intron 2, HLA-G7 transcripts retain the capacity to be translated as soluble truncated HLA-G proteins bearing the alpha1 domain linked to two specific aminoacids encoded by intron 2. Expression vectors containing cDNAs encoding HLA-G5, -G6, and -G7 isoforms were transfected into human cell lines. The presence of translated HLA-G5, -G6, and -G7 proteins was detected in protein extracts of transfected cells by Western blot and immunoprecipitation, but only the full length HLA-G5 soluble isoform could be clearly detected as a secreted protein in both transfected cells supernatants and body fluids.
Paul
P
P
Service de Recherches en Hémato-Immunologie, CEA/DRM/DSV, Hôpital St. Louis, Institut Universitaire d'Hématologie, Cedex 10, Paris, France. paul@dsvidf.cea.fr
Cabestre
F A
FA
Ibrahim
E C
EC
Lefebvre
S
S
Khalil-Daher
I
I
Vazeux
G
G
Quiles
R M
RM
Bermond
F
F
Dausset
J
J
Carosella
E D
ED
D017398:Alternative Splicing; D001483:Base Sequence; D001706:Biopsy; D015152:Blotting, Northern; D015153:Blotting, Western; D017077:Culture Media, Conditioned / Q000032:analysis; D018076:DNA, Complementary; D006680:HLA Antigens / Q000235:genetics* / Q000378:metabolism*; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008545:Melanoma / Q000235:genetics / Q000473:pathology; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D014162:Transfection; D014407:Tumor Cells, Cultured
D017077:Culture Media, Conditioned; D018076:DNA, Complementary; D006680:HLA Antigens; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I; D020033:Protein Isoforms; D012333:RNA, Messenger