Evidence for a direct role of the disease modifier SCNM1 in splicing.
We originally isolated Scnm1 as a disease modifier gene that is required for efficient in vivo splicing of a mutant splice donor site in the sodium channel Scn8a. It was previously unclear whether the modifier effect on splicing was direct or indirect. We now report evidence that sodium channel modifier 1 (SCNM1) has a direct role in splicing. SCNM1 protein interacts with the spliceosome protein U1-70K in the yeast two-hybrid system, and is co-localized with U1-70K in nuclear speckles in mammalian cells. SCNM1 is also co-immunoprecipitated with the spliceosomal core Smith (Sm) proteins and demonstrates functional activity in a minigene splicing assay. In a yeast two-hybrid screen, SCNM1 interacted with LUC7L2, a mammalian homolog of a yeast protein involved in recognition of non-consensus splice donor sites. This interaction requires the acidic C-terminal domain of SCNM1 which is truncated by the disease susceptibility variant Scnm1(R187X) in mouse strain C57BL/6J. Luc7L2 transcripts are widely distributed in mammalian tissues, and undergo alternative splicing and polyadenylation. LUC7L2 is also co-localized with U1-70K and may function with SCNM1 in recognition of weak splice donor sites. In summary, Scnm1 is the first example of a modifier gene which influences disease severity through a trans-effect on splicing of the disease gene transcript.
Department of Human Genetics, University of Michigan School of Medicine, Ann Arbor, MI 48109-0618, USA.
Viive M
VM
Howell
Julie M
JM
Jones
Sarah K
SK
Bergren
Li
L
Li
Allison C
AC
Billi
Matthew R
MR
Avenarius
Miriam H
MH
Meisler
D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D030342:Genetic Diseases, Inborn / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008954:Models, Biological; D008969:Molecular Sequence Data; D026723:Polyadenylation; D011485:Protein Binding; D012326:RNA Splicing / Q000235:genetics*; D000072260:RNA Splicing Factors; D016601:RNA-Binding Proteins / Q000378:metabolism; D017381:Spliceosomes / Q000378:metabolism; D014162:Transfection
D002352:Carrier Proteins; C527494:Luc7L2 protein, mouse; D000072260:RNA Splicing Factors; D016601:RNA-Binding Proteins; C476996:Scnm1 protein, mouse