Autosomal-dominant retinitis pigmentosa caused by a mutation in SNRNP200, a gene required for unwinding of U4/U6 snRNAs.
Mutations in genes associated with the U4/U6-U5 small nuclear ribonucleoprotein (snRNP) complex of the spliceosome are implicated in autosomal-dominant retinitis pigmentosa (adRP), a group of progressive retinal degenerative disorders leading to visual impairment, loss of visual field, and even blindness. We recently assigned a locus (RP33) for adRP to 2cen-q12.1, a region that harbors the SNRNP200 gene encoding hBrr2, another U4/U6-U5 snRNP component that is required for unwinding of U4/U6 snRNAs during spliceosome activation and for disassembly of the spliceosome. Here, we report the identification of a missense mutation, c.3260C>T (p.S1087L), in exon 25 of the SNRNP200 gene in an RP33-linked family. The c.3260C>T substitution showed complete cosegregation with the retinitis pigmentosa (RP) phenotype over four generations, but was absent in a panel of 400 controls. The p.S1087L mutation and p.R1090L, another adRP-associated allele, reside in the "ratchet" helix of the first of two Sec63 domains implicated in the directionality and processivity of nucleic acid unwinding. Indeed, marked defects in U4/U6 unwinding, but not U4/U6-U5 snRNP assembly, were observed in budding yeast for the analogous mutations (N1104L and R1107L) of the corresponding Brr2p residues. The linkage of hBrr2 to adRP suggests that the mechanism of pathogenesis for splicing-factor-related RP may fundamentally derive from a defect in hBrr2-dependent RNA unwinding and a consequent defect in spliceosome activation.
Zhao
Chen
C
Tianjin Eye Hospital, Tianjin Medical University, 4 Gansu Road, Tianjin 300040, PR China.
Bellur
Deepti L
DL
Lu
Shasha
S
Zhao
Feng
F
Grassi
Michael A
MA
Bowne
Sara J
SJ
Sullivan
Lori S
LS
Daiger
Stephen P
SP
Chen
Li Jia
LJ
Pang
Chi Pui
CP
Zhao
Kanxing
K
Staley
Jonathan P
JP
Larsson
Catharina
C
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001483:Base Sequence; D005091:Exons; D005260:Female; D005799:Genes, Dominant; D005819:Genetic Markers; D006367:HeLa Cells; D006801:Humans; D007930:Leucine / Q000378:metabolism; D008126:Lod Score; D008297:Male; D018895:Microsatellite Repeats; D008969:Molecular Sequence Data; D009154:Mutation; D020125:Mutation, Missense; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D010375:Pedigree; D020161:Physical Chromosome Mapping; D012326:RNA Splicing; D012342:RNA, Small Nuclear / Q000235:genetics / Q000378:metabolism; D012174:Retinitis Pigmentosa / Q000235:genetics*; D017414:Ribonucleoprotein, U4-U6 Small Nuclear / Q000235:genetics* / Q000378:metabolism*; D017415:Ribonucleoprotein, U5 Small Nuclear; D017411:Ribonucleoproteins, Small Nuclear / Q000235:genetics*; D017386:Sequence Homology, Amino Acid
D005819:Genetic Markers; D009687:Nuclear Proteins; D012342:RNA, Small Nuclear; D017414:Ribonucleoprotein, U4-U6 Small Nuclear; D017415:Ribonucleoprotein, U5 Small Nuclear; D017411:Ribonucleoproteins, Small Nuclear; C545711:SNRNP200 protein, human; D007930:Leucine