Nuclear clusterin/XIP8, an x-ray-induced Ku70-binding protein that signals cell death.
Clusterin [CLU, a.k.a. TRPM-2, SGP-2, or ionizing radiation (IR)-induced protein-8 (XIP8)] was implicated in apoptosis, tissue injury, and aging. Its function remains elusive. We reisolated CLU/XIP8 by yeast two-hybrid analyses using as bait the DNA double-strand break repair protein Ku70. We show that a delayed (2-3 days), low-dose (0.02-10 Gy) IR-inducible nuclear CLU/XIP8 protein coimmunoprecipitated and colocalized (by confocal microscopy) in vivo with Ku70/Ku80, a DNA damage sensor and key double-strand break repair protein, in human MCF-7:WS8 breast cancer cells. Overexpression of nuclear CLU/XIP8 or its minimal Ku70 binding domain (120 aa of CLU/XIP8 C terminus) in nonirradiated MCF-7:WS8 cells dramatically reduced cell growth and colony-forming ability concomitant with increased G(1) cell cycle checkpoint arrest and increased cell death. Enhanced expression and accumulation of nuclear CLU/XIP8-Ku70/Ku80 complexes appears to be an important cell death signal after IR exposure.
Yang
C R
CR
Laboratory of Molecular Stress Responses, Departments of Radiation Oncology, Pharmacology and Pathology, Ireland Comprehensive Cancer Center, Case Western Reserve University, 10900 Euclid Avenue (BRB-326 East), Cleveland, OH 44106-4942, USA.
Leskov
K
K
Hosley-Eberlein
K
K
Criswell
T
T
Pink
J J
JJ
Kinsella
T J
TJ
Boothman
D A
DA
D000230:Adenocarcinoma / Q000473:pathology; D020816:Amino Acid Motifs; D034961:Antigens, Nuclear; D001943:Breast Neoplasms / Q000473:pathology; D016923:Cell Death / Q000502:physiology*; D002467:Cell Nucleus / Q000378:metabolism; D051152:Clusterin; D004249:DNA Damage; D004265:DNA Helicases; D004260:DNA Repair / Q000502:physiology*; D018076:DNA, Complementary / Q000235:genetics; D004273:DNA, Neoplasm / Q000528:radiation effects; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005260:Female; D005434:Flow Cytometry; D015972:Gene Expression Regulation, Neoplastic / Q000528:radiation effects; D015723:Gene Library; D017930:Genes, Reporter; D006023:Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D049452:Green Fluorescent Proteins; D006801:Humans; D000072200:Ku Autoantigen; D008164:Luminescent Proteins / Q000235:genetics; D018613:Microscopy, Confocal; D018832:Molecular Chaperones; D009687:Nuclear Proteins / Q000378:metabolism*; D011485:Protein Binding; D011498:Protein Precursors / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D014407:Tumor Cells, Cultured; D020798:Two-Hybrid System Techniques
D034961:Antigens, Nuclear; C495242:CLU protein, human; D051152:Clusterin; D018076:DNA, Complementary; D004273:DNA, Neoplasm; D004268:DNA-Binding Proteins; D006023:Glycoproteins; D008164:Luminescent Proteins; D018832:Molecular Chaperones; D009687:Nuclear Proteins; D011498:Protein Precursors; D029701:Saccharomyces cerevisiae Proteins; C081647:high affinity DNA-binding factor, S cerevisiae; D049452:Green Fluorescent Proteins; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; D017346:Protein Serine-Threonine Kinases; D004265:DNA Helicases; C106893:XRCC5 protein, human; C000606509:Xrcc6 protein, human; D000072200:Ku Autoantigen