title: Differential localisation of PARP-1 N-terminal fragment in PARP-1(+/+) and PARP-1(-/-) murine cells.
abstract: Human PARP family consists of 17 members of which PARP-1 is a prominent member and plays a key role in DNA repair pathways. It has an N-terminal DNA-binding domain (DBD) encompassing the nuclear localisation signal (NLS), central automodification domain and C-terminal catalytic domain. PARP-1 accounts for majority of poly-(ADP-ribose) polymer synthesis that upon binding to numerous proteins including PARP itself modulates their activity. Reduced PARP-1 activity in ageing human samples and its deficiency leading to telomere shortening has been reported. Hence for cell survival, maintenance of genomic integrity and longevity presence of intact PARP-1 in the nucleus is paramount. Although localisation of full-length and truncated PARP-1 in PARP-1 proficient cells is well documented, subcellular distribution of PARP-1 fragments in the absence of endogenous PARP-1 is not known. Here we report the differential localisation of PARP-1 N-terminal fragment encompassing NLS in PARP-1(+/+) and PARP-1(-/-) mouse embryo fibroblasts by live imaging of cells transiently expressing EGFP tagged fragment. In PARP-1(+/+) cells the fragment localises to the nuclei presenting a granular pattern. Furthermore, it is densely packaged in the midsections of the nucleus. In contrast, the fragment localises exclusively to the cytoplasm in PARP-1(-/-) cells. Flourescence intensity analysis further confirmed this observation indicating that the N-terminal fragment requires endogenous PARP-1 for its nuclear transport. Our study illustrates the trafficking role of PARP-1 independently of its enzymatic activity and highlights the possibility that full-length PARP-1 may play a key role in the nuclear transport of its siblings and other molecules.
authors: Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 1QP, United Kingdom.
authors: Ida Rachel
authors: IR
authors: Rajiah
authors: Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 1QP, United Kingdom.
authors: Jeremy
authors: J
authors: Skepper
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism*; D002478:Cells, Cultured; D003593:Cytoplasm / Q000378:metabolism*; D004260:DNA Repair; D005347:Fibroblasts / Q000502:physiology*; D055785:Gene Knockdown Techniques; D006801:Humans; D051379:Mice; D019913:Nuclear Localization Signals / Q000235:genetics; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism*; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary / Q000235:genetics; D021381:Protein Transport
chemical_list: D019913:Nuclear Localization Signals; D010446:Peptide Fragments; C499321:Parp1 protein, mouse; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases
keywords: DNA binding domain; DNA repair; Poly(ADP-ribose); fluorescence imaging; nuclear transport