title: Overexpression of a protein fragment of RNA helicase A causes inhibition of endogenous BRCA1 function and defects in ploidy and cytokinesis in mammary epithelial cells.
abstract: The breast- and ovarian-specific tumor suppressor, BRCA1, has been implicated to function in many nuclear processes, including DNA damage repair, recombination, transcription, ubiquitination, cell cycle checkpoint enforcement, and centrosome regulation. Utilizing a previously described interaction between BRCA1 and RNA helicase A (RHA), we have developed a dominant-negative approach to block BRCA1 function in human breast epithelial cells. Overexpression of a truncated RHA peptide that can bind to the BRCA1 carboxy-terminus prevents normal BRCA1 function, such as BRCA1 association with nuclear foci following DNA damage. Overexpression of this dominant-negative protein induces pleomorphic nuclei, aberrant mitoses with extra centrosomes, and tetraploidy. This model system allows us to observe changes to mammary epithelial cells that occur acutely following loss of BRCA1 function. Furthermore, inhibition of BRCA1 via overexpressing the RHA fragment coincides with a reduction in PARP-1 protein expression, suggesting a possible mechanism for BRCA1 in the maintenance of genomic integrity.
authors.affiliation: Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
authors.forename: Brian P
authors.initials: BP
authors.lastname: Schlegel
authors.forename: Lea M
authors.initials: LM
authors.lastname: Starita
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Parvin
mesh_terms: D000782:Aneuploidy; D001324:Autoantigens / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D019313:BRCA1 Protein / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000502:physiology; D001665:Binding Sites; D001859:Bone Neoplasms / Q000473:pathology; D001940:Breast / Q000166:cytology / Q000378:metabolism*; D002455:Cell Division; D002467:Cell Nucleus / Q000648:ultrastructure; D002471:Cell Transformation, Neoplastic / Q000235:genetics; D002478:Cells, Cultured; D018385:Centrosome / Q000648:ultrastructure; D053487:DEAD-box RNA Helicases; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D005260:Female; D019398:Genes, BRCA1; D005799:Genes, Dominant; D006801:Humans; D009363:Neoplasm Proteins; D012516:Osteosarcoma / Q000473:pathology; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D011065:Poly(ADP-ribose) Polymerases / Q000502:physiology*; D017434:Protein Structure, Tertiary; D020365:RNA Helicases / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000502:physiology
chemical_list: D001324:Autoantigens; D019313:BRCA1 Protein; D009363:Neoplasm Proteins; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; D011065:Poly(ADP-ribose) Polymerases; C098487:DHX9 protein, human; D053487:DEAD-box RNA Helicases; D020365:RNA Helicases