Research Papers: Gerotarget (Focus on Aging):
Different non-synonymous polymorphisms modulate the interaction of the WRN protein to its protein partners and its enzymatic activities
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Jean-Philippe Gagné1, Sophie Lachapelle2, Chantal Garand1, Serges P. Tsofack1, Yan Coulombe2, Marie-Christine Caron2, Guy G. Poirier1, Jean-Yves Masson2 and Michel Lebel1
1 Centre de Recherche du CHU de Québec, Pavillon CHUL Université Laval, Faculté de Médecine, Québec, Canada
2 Centre de Recherche sur le Cancer de l’Université Laval, Hôpital Hôtel-Dieu de Québec, Québec, Québec, Canada
Michel Lebel, email:
Keywords: mass spectrometry, proteomics, werner syndrome, polymorphism, exonuclease, Gerotarget
Received: October 30, 2015 Accepted: September 27, 2016 Published: November 14, 2016
Werner syndrome (WS) is characterized by the premature onset of several age-associated pathologies including cancer. The protein defective in WS patients (WRN) is a helicase/exonuclease involved in DNA replication and repair. Here, we present the results of a large-scale proteome analysis that has been undertaken to determine protein partners of different polymorphic WRN proteins found with relatively high prevalence in the human population. We expressed different fluorescently tagged-WRN (eYFP-WRN) variants in human 293 embryonic kidney cells (HEK293) and used a combination of affinity-purification and mass spectrometry to identify different compositions of WRN-associated protein complexes. We found that a WRN variant containing a phenylalanine residue at position 1074 and an arginine at position 1367 (eYFP-WRN(F-R)) possesses more affinity for DNA-PKc, KU86, KU70, and PARP1 than a variant containing a leucine at position 1074 and a cysteine at position 1367 (eYFP-WRN(L-C)). Such results were confirmed in a WRN-deficient background using WS fibroblasts. Interestingly, the exonuclase activity of WRN recovered from immunoprecipitated eYFP-WRN(L-C) variant was lower than the eYFP-WRN(F-R) in WS cells. Finally, HEK293 cells and WS fibroblasts overexpressing the eYFP-WRN(F-R) variant were more resistant to the benzene metabolite hydroquinone than cells expressing the eYFP-WRN(L-C) variant. These results indicate that the protein-protein interaction landscape of WRN is subject to modulation by polymorphic amino acids, a characteristic associated with distinctive cell survival outcome.
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