Biochemical and Biophysical Research Communications, Vol.426, No.1, 12-17, 2012
Yeast hnRNP-related proteins contribute to the maintenance of telomeres
Telomeres protect the ends of linear chromosomes, which if eroded to a critical length can become uncapped and lead to replicative senescence. Telomerase maintains telomere length in some cells, but inappropriate expression facilitates the immortality of cancer cells. Recently, proteins involved in RNA processing and ribosome assembly, such as hnRNP (heterogeneous nuclear ribonucleoprotein) A1, have been found to participate in telomere maintenance in mammals. The Saccharomyces cerevisiae protein Np13 shares significant amino acid sequence similarities with hnRNP A1. We found that deleting NPL3 accelerated the senescence of telomerase null cells. The highly conserved RNA recognition motifs (RRM) in Np13 appear to be important for preventing faster senescence. Np13 preferentially binds telomere sequences in vitro, suggesting that Np13 may affect telomeres directly. Despite similarities between the two proteins, human hnRNP A1 is unable to complement the lack of Np13 to rescue accelerated senescence in tlc1 np13 cells. Deletion of CBC2, which encodes another hnRNP-related protein that associates with Np13, also accelerates senescence. Potential mechanisms by which hnRNP-related proteins maintain telomeres are discussed. (C) 2012 Elsevier Inc. All rights reserved.