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ID 106072
Title Alternative
Homeodomain interacting protein kinase 2はheterochromatin protein 1γとの相互作用を介してDNA損傷応答を制御する
HP1γ as a novel target for HIPK2
Author
Akaike, Yoko Tokushima University
Kurokawa, Ken Tokushima University
Kajita, Keisuke Tokushima University
Kano, Shizuka Tokushima University
Keywords
DNA damage response
HIPK2
HP1γ
chromatin remodeling
DNA damage repair
Content Type
Thesis or Dissertation
Description
Homeodomain-interacting protein kinase 2 (HIPK2) is a potential tumor suppressor that plays a crucial role in the DNA damage response (DDR) by regulating cell cycle checkpoint activation and apoptosis. However, it is unclear whether HIPK2 exerts distinct roles in DNA damage repair. The aim of this study was to identify novel target molecule(s) of HIPK2, which mediates HIPK2-dependent DNA damage repair. HIPK2-knockdown human colon cancer cells (HCT116) or hipk1/hipk2 double-deficient mouse embryonic fibroblasts could not remove histone H2A.X phosphorylated at Ser139 (γH2A.X) after irradiation with a sublethal dose (10 J/m2) of ultraviolet (UV)-C, resulting in apoptosis. Knockdown of HIPK2 in p53-null HCT116 cells similarly promoted the UV-C-induced γH2A.X accumulation and apoptosis. Proteomic analysis of HIPK2-associated proteins using liquid chromatography-tandem mass spectrometry identified heterochromatin protein 1γ (HP1γ) as a novel target for HIPK2. Immunoprecipitation experiments with HCT116 cells expressing FLAG-tagged HIPK2 and one of the HA-tagged HP1 family members demonstrated that HIPK2 specifically associated with HP1γ, but not with HP1α or HP1β, through its chromo-shadow domain. Mutation of the HP1box motif (883-PTVSV-887) within HIPK2 abolished the association. HP1γ knockdown also enhanced accumulation of γH2A.X and apoptosis after sublethal UV-C irradiation. In vitro kinase assay demonstrated an HP1γ-phosphorylating activity of HIPK2. Sublethal UV-C irradiation phosphorylated HP1γ. This phosphorylation was absent in endogenous HIPK2-silenced cells with HIPK2 3’UTR siRNA. Overexpression of FLAG-HIPK2, but not the HP1box-mutated or kinase-dead HIPK2 mutant, in the HIPK2-silenced cells increased HP1γ binding to trimethylated (Lys9) histone H3 (H3K9me3), rescued the UV-C-induced phosphorylation of HP1γ, triggered release of HP1γ from histone H3K9me3, and suppressed γH2A.X accumulation. Our results suggest that HIPK2-dependent phosphorylation of HP1γ may participate in the regulation of dynamic interaction between HP1γ and histone H3K9me3 to promote DNA damage repair. This HIPK2/HP1γ pathway may uncover a new functional aspect of HIPK2 as a tumor suppressor.
Journal Title
Oncogene
ISSN
14765594
09509232
NCID
AA12190066
AA10687380
Publisher
Springer Nature
Volume
34
Issue
26
Start Page
3463
End Page
3473
Published Date
2014-08-25
Remark
内容要旨・審査要旨・論文本文の公開
内容要旨・審査要旨 : LID201404221016.pdf
論文本文 : k2672_fulltext.pdf
本論文は,著者Yoko Akaikeの学位論文として提出され,学位審査・授与の対象となっている。
著者の申請により要約(2014-05-23公開)に替えて論文全文を公開(2020-01-20)
EDB ID
DOI (Published Version)
URL ( Publisher's Version )
FullText File
language
eng
TextVersion
ETD
MEXT report number
甲第2672号
Diploma Number
甲医第1196号
Granted Date
2014-03-24
Degree Name
Doctor of Medical Science
Grantor
Tokushima University
departments
Medical Sciences