The defect in Fas mRNA expression in MRL/lpr mice is associated with insertion of the retrotransposon, ETn.
Fas is a cell surface protein of the tumor necrosis factor receptor, nerve growth factor receptor, CD40 family, and is involved in the control of lymphocyte apoptosis. A mutation in the Fas gene in MRL/lpr mice results in massive lymphoproliferation (lpr) and accelerated autoimmunity. To further study the nature of this defect, Fas mRNA expression was evaluated by reverse transcriptase polymerase chain reaction as well as by Northern blotting. These studies revealed that the wild-type Fas message was produced at approximately 10-fold lower levels in the lpr compared with the ++ substrain of MRL mice. In addition to the wild-type transcript, lpr mice also synthesized chimeric transcripts containing an insertion of the early retrotransposon (ETn). Molecular cloning and nucleotide sequencing of a Fas-ETn chimeric cDNA suggested that the striking reduction in wild-type Fas mRNA levels and the presence of aberrant transcripts in MRL/lpr mice are most likely explained by the insertion of the ETn retrotransposon into an intron of the Fas gene and induction of alternative splicing involving the 5' ETn long terminal repeat.
Chu
J L
JL
Hospital for Special Surgery, Cornell University Medical Center, New York, New York 10021.
Drappa
J
J
Parnassa
A
A
Elkon
K B
KB
D000818:Animals; D000954:Antigens, Surface / Q000235:genetics*; D001327:Autoimmune Diseases / Q000235:genetics*; D001483:Base Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D004247:DNA; D004251:DNA Transposable Elements; D008221:Lymphoid Tissue / Q000378:metabolism; D051379:Mice; D008809:Mice, Inbred C3H; D008969:Molecular Sequence Data; D009154:Mutation; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000096:biosynthesis* / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid; D019014:fas Receptor
D000954:Antigens, Surface; D004251:DNA Transposable Elements; D012333:RNA, Messenger; D019014:fas Receptor; D004247:DNA