Human Molecular Genetics Advance Access originally published online on March 17, 2009
Human Molecular Genetics 2009 18(11):2014-2023; doi:10.1093/hmg/ddp125
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A mutation linked to retinitis pigmentosa in HPRP31 causes protein instability and impairs its interactions with spliceosomal snRNPs
ková
k*
Department of RNA Biology, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Víde
ská 1083, 142 20 Prague, Czech Republic
* To whom correspondence should be addressed. Tel: +420 296443118; Fax: +420 224310955; Email: stanek{at}img.cas.cz
Received January 2, 2009; Revised February 27, 2009; Accepted March 13, 2009
The AD29 mutation in HPRP31 belongs to a series of mutations that were initially linked with the autosomal dominant disorder retinitis pigmentosa (RP) type 11. The HPRP31 gene encodes the hPrp31 protein that specifically associates with spliceosomal small nuclear ribonucleoprotein particles (snRNPs). Despite intensive research, it is still unclear how the AD29 (Ala216Pro) mutation causes RP. In this study, we report that the expression of this mutant protein affects cell proliferation and alters the structure of nuclear Cajal bodies that are connected with snRNP metabolism. Interestingly, these effects can be reversed by the over-expression of the hPrp6 protein, a binding partner of hPrp31. Although Ala216 is not contained within the U4 or U5 snRNP interacting domains, we present several lines of evidence that demonstrate that the association between the AD29 mutant and snRNPs in the cell nucleus is significantly reduced. Finally, we show that the stability of the AD29 mutant is severely affected resulting in its rapid degradation. Taken together, our results indicate that the Ala216Pro mutation destabilizes the hPrp31 protein structure in turn reducing its interaction with snRNP binding partners and leading to its rapid degradation. These findings significantly impact our understanding of the molecular mechanisms underlying RP and suggest that the insufficiency of the functional hPrp31 protein combined with the potential cytotoxicity associated with the expression the AD29 mutant are at least partially causative of the RP phenotype.
The authors wish it to be known that, in their opinion, the first two authors should be regarded as joint First Authors.