Abstract
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.
Publication types
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Research Support, U.S. Gov't, Non-P.H.S.
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Adenocarcinoma / pathology
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Amino Acid Motifs
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Antigens, Nuclear*
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Breast Neoplasms / pathology
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Cell Death / physiology*
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Cell Nucleus / metabolism
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Clusterin
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DNA Damage
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DNA Helicases*
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DNA Repair / physiology*
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DNA, Complementary / genetics
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DNA, Neoplasm / radiation effects
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DNA-Activated Protein Kinase
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DNA-Binding Proteins / metabolism*
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Female
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Flow Cytometry
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Gene Expression Regulation, Neoplastic / radiation effects
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Gene Library
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Genes, Reporter
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Glycoproteins / chemistry
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Glycoproteins / genetics
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Glycoproteins / physiology*
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Green Fluorescent Proteins
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Humans
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Ku Autoantigen
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Luminescent Proteins / genetics
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Microscopy, Confocal
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Molecular Chaperones*
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Nuclear Proteins / metabolism*
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Protein Binding
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Protein Precursors / metabolism
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Protein Serine-Threonine Kinases / physiology
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae Proteins*
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Tumor Cells, Cultured
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Two-Hybrid System Techniques
Substances
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Antigens, Nuclear
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CLU protein, human
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Clusterin
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DNA, Complementary
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DNA, Neoplasm
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DNA-Binding Proteins
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Glycoproteins
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Luminescent Proteins
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Molecular Chaperones
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Nuclear Proteins
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Protein Precursors
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Saccharomyces cerevisiae Proteins
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high affinity DNA-binding factor, S cerevisiae
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Green Fluorescent Proteins
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DNA-Activated Protein Kinase
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PRKDC protein, human
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Protein Serine-Threonine Kinases
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DNA Helicases
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XRCC5 protein, human
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Xrcc6 protein, human
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Ku Autoantigen