Reduced expression of the endothelin receptor type B gene in piebald mice caused by insertion of a retroposon-like element in intron 1.
Mice carrying the piebald mutation exhibit white coat spotting due to the regional absence of neural crest-derived melanocytes. We reported previously that the piebald locus encodes the Ednrb gene and that piebald mice express low levels of structurally intact Ednrb mRNA and EDNRB protein (Hosoda, K., Hammer, R. E., Richardson, J. A., Baynash, A. G., Cheung, J. C., Giaid, A., and Yanagisawa, M. (1994) Cell 79, 1267-1276). Here, we report that both the life span of the Ednrb mRNA and the promoter activity of the Ednrb gene are indistinguishable between wild-type and piebald mice. Introns 2-6 of the Ednrb gene in piebald mice were correctly excised with an efficiency indistinguishable from those in wild-type mice in exon trapping experiments. We found that the piebald allele of the Ednrb gene has a 5.5-kb retroposon-like element in intron 1 possessing canonical sequences of a polyadenylation signal and a splice acceptor site. Abnormal hybrid transcripts carrying exon 1 of the Ednrb gene and a portion of the 5.5-kb element are expressed in piebald mice. The insertion of the 5.5-kb element into a heterologous intron in a mammalian expression vector markedly reduced the expression of the reporter gene. Premature termination and aberrant splicing of the Ednrb transcript caused by the retroposon-like element in intron 1 lead to a reduced level of the normal Ednrb transcript, which is responsible for the partial loss-of-function phenotype of piebald mice.
Yamada
Takahisa
T
Howard Hughes Medical Institute and the Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9050, USA. tyamada@kais.kyoto-u.ac.jp
Ohtani
Shin
S
Sakurai
Takeshi
T
Tsuji
Takehito
T
Kunieda
Tetsuo
T
Yanagisawa
Masashi
M
D000483:Alleles; D017398:Alternative Splicing; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D019556:COS Cells; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D018076:DNA, Complementary / Q000378:metabolism; D005091:Exons; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D005822:Genetic Vectors; D007438:Introns; D008156:Luciferases / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010641:Phenotype; D010957:Plasmids / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D044023:Receptor, Endothelin B / Q000096:biosynthesis* / Q000235:genetics*; D018626:Retroelements; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014018:Tissue Distribution; D014162:Transfection
D018076:DNA, Complementary; D012333:RNA, Messenger; D044023:Receptor, Endothelin B; D018626:Retroelements; D008156:Luciferases