Telomeric DNA-binding activities of heterogeneous nuclear ribonucleoprotein A3 in vitro and in vivo.
Telomeres are dynamic DNA-protein complexes that protect the ends of linear chromosome. Telomere-binding proteins play crucial role in the maintenance of telomeres. HnRNP A3 has been shown recently to bind specifically to single-stranded telomeric DNA in vitro, although its in vivo telomere function remains unknown. In this study, the DNA-binding properties of hnRNP A3 in vitro as well as its putative role of telomere maintenance in vivo were investigated. The minimal sequence for hnRNP A3 binding to DNA was determined as an undecamer with the following consensus sequence 5'-[T/C]AG[G/T]NN[T/C]AG[G/T]N-3'. Confocal microscopy and chromatin-immunoprecipitation (ChIP) analyses showed that hnRNP A3 is associated with telomere in vivo. Knocking-down the expression of hnRNP A3 had no effect on telomere length maintenance and did not affect cell proliferation. In contrast, overexpression of hnRNP A3 resulted in the production of steady-state short telomeres in OECM1 cells. These results suggest that hnRNP A3 is associated with telomere in vivo and acts as a negative regulator of telomere length maintenance.
Huang
Pei-Rong
PR
Department of Molecular and Cellular Biology, Chang Gung University, Tao-Yuan. Taiwan.
Hung
Shu-Chen
SC
Wang
Tzu-Chien V
TC
D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002460:Cell Line; D045744:Cell Line, Tumor; D047369:Chromatin Immunoprecipitation; D004247:DNA / Q000235:genetics / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D056945:Hep G2 Cells; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D018613:Microscopy, Confocal; D009154:Mutation; D011485:Protein Binding; D034622:RNA Interference; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016615:Telomere / Q000235:genetics / Q000378:metabolism*
C502034:HNRNPA3 protein, human; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D004247:DNA