title: The human Rothmund-Thomson syndrome gene product, RECQL4, localizes to distinct nuclear foci that coincide with proteins involved in the maintenance of genome stability.
abstract: Rothmund-Thomson syndrome (RTS) is a human genetic disorder characterized by genome instability, cancer susceptibility and premature aging. The gene defective in a subset of RTS cases, RECQL4, encodes a member of the RecQ family of DNA helicases. To better define the function of the RECQL4 protein, we have determined its subcellular localization. We have raised antibodies against the N- and C-terminal parts of RECQL4 and could show that in various human cells endogenous RECQL4 forms discrete nuclear foci that colocalize with promyelotic leukaemia protein (PML). The number of foci and their colocalization with PML does not significantly change after induction of different types of DNA damages. Silencing of RECQL4 expression by siRNA causes a significant reduction in RECQL4 nuclear foci formation. Furthermore, we demonstrate that RECQL4 foci coincide with foci formed by human Rad51 and regions of single-stranded DNA after induction of DNA double-strand breaks. In agreement with this, we also show that RECQL4 and Rad51 form a complex in human cells. Our findings suggest a role for RECQL4 in the repair of DNA double-strand breaks by homologous recombination and shed new light onto RECQL4's function in human cells.
authors.affiliation: Institute of Vet. Biochemistry and Molecular Biology, University of Zürich, Winterthurerstr. 190, 8057 Zürich, Switzerland.
authors.forename: Maja
authors.initials: M
authors.lastname: Petkovic
authors.forename: Tobias
authors.initials: T
authors.lastname: Dietschy
authors.forename: Raimundo
authors.initials: R
authors.lastname: Freire
authors.forename: Renjie
authors.initials: R
authors.lastname: Jiao
authors.forename: Igor
authors.initials: I
authors.lastname: Stagljar
mesh_terms: D000251:Adenosine Triphosphatases / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D002467:Cell Nucleus / Q000201:enzymology / Q000235:genetics; D002478:Cells, Cultured; D004249:DNA Damage; D004265:DNA Helicases / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D004260:DNA Repair; D004277:DNA, Single-Stranded / Q000235:genetics / Q000378:metabolism; D042822:Genomic Instability / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D009363:Neoplasm Proteins / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D000071156:Promyelocytic Leukemia Protein; D034741:RNA, Small Interfering / Q000235:genetics; D051135:Rad51 Recombinase / Q000378:metabolism; D053484:RecQ Helicases; D011038:Rothmund-Thomson Syndrome / Q000201:enzymology / Q000235:genetics*; D014157:Transcription Factors / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000378:metabolism
chemical_list: D004277:DNA, Single-Stranded; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D000071156:Promyelocytic Leukemia Protein; D034741:RNA, Small Interfering; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; C070576:PML protein, human; C495153:RAD51 protein, human; D051135:Rad51 Recombinase; D000251:Adenosine Triphosphatases; C506731:RECQL4 protein, human; D004265:DNA Helicases; D053484:RecQ Helicases