This website was created as a project for Genetics 677, an undergraduate course at UW Madison.
Conclusions
The purpose of this website is to use multiple bioinformatics databases to collect and analyze data to more comprehensively understand Werner syndrome and the gene responsible, WRN. Homology and phylogeny searches yielded very similar results, as Pan troglodytes, Canis familiaris, and Mus musculus retain the most sequence similarity, respectively. Protein homologies showed a higher correlation with the human WRN than mRNA sequences, which was unsurprising because proteins are often conserved among species. Additionally, differences in mRNA structure, alternative splicing, and variability among codons could have accounted for a slightly lower sequence homology among mRNAs.
Gene ontology provided a backdrop on which to understand the functional properties of WRN, identifying roles involved with DNA binding, cellular aging, and helicase functions. These results were logical and to be expected because WRN is a member of the RecQ family of helicase-like proteins. Analysis of DNA motifs and protein domains within WRN also supported the ontological terms that were found. Most importantly for the purposes of this website was the nucleolar localization of the WRN protein. This was identified by gene ontology, and supported in the literature as a nucleolar localization signal discovered within the C-terminus of the protein.
The WRN gene is made up of 5 functionally important domains. In order from 5' to 3' they include: a 3'-5' exonuclease for proofreading activity, a DEAD/DEAH box helicase to unwind DNA for transcription, a helicase conserved C-terminal domain, an RQC high affinity DNA binding domain, and an HRDC domain important for nucleic acid binding. Of the 1,432 amino acids in WRN, 590 amino acids make up the functional domains. Analysis of DNA motifs was not helpful in understanding functional properties of the gene because the motifs identified by the database were general transcription factors, heat shock factors, and maize activator genes. It is unknown what role these motifs play in development of the WRN protein or their significance.
WRN yielded protein interactions only within the human and Caenorhabditis elegans databases. Among the human database, most interactions were related to DNA replication and repair. The most significant interaction was the Bloom syndrome protein BLM, which although surprising at first, was later discovered to also be a member of the RecQ family of helicase-like proteins. It is also interesting to note that individuals with Bloom syndrome share at least some similar symptoms as those with Werner syndrome, including a predisposition to developing cancer and diabetes. Within the Caenorhabditis elegans database, the most notable protein interaction was that of air-2, a protein kinase related to the drosophila and budding yeast IpI1 proteins. The kinase has recently been identified as a target for cancer therapy. This aspect may have significance, as it is a secondary complication of Werner syndrome, although the low sequence homology of the Caenorhabditis elegans homolog wrn-1 may prove to be problematic in applying this data to humans successfully.
The bioinformatics programs that yielded the least amount of information regarding WRN and Werner syndrome were the RNAi database, chemical genetics database, and microarray database. A more focused effort to produce RNAi and microarray data relating to WRN and Werner syndrome needs to be done before any information can be applicable. The only study observed that identified a treatment for Werner syndrome was in the study conducted by Massip et al. titled "Vitamin C restores healthy aging in a mouse model for Werner syndrome" (1). Although the results of this study appear very promising, there has yet to be a follow up study in humans because the 9-month treatment program would not yet be finished even if trials had begun immediately after publishing in September 2009.
The main conclusion of this study is that the importance of the nucleolar localization signal of WRN, found in the C-terminus, is responsible for a majority of the diagnosed cases of Werner syndrome. Further research can be done to focus on the C-terminus and the 5 amino acid nucleolar localization signal. The potential of this aspect of Werner syndrome is outlined further in the Future Direction page of this website.
References
1. Massip L, Garand C, Paquet E, Cogger V et al. (2010). Vitamin C restores healthy aging in a mouse model for Werner syndrome. The FASEB journal 24, 158-174. doi:10.1096/fj.09-137133.
1. Massip L, Garand C, Paquet E, Cogger V et al. (2010). Vitamin C restores healthy aging in a mouse model for Werner syndrome. The FASEB journal 24, 158-174. doi:10.1096/fj.09-137133.
