Kaiso mainly locates in the nucleus in vivo and binds to methylated, but not hydroxymethylated DNA.
OBJECTIVE
Kaiso is upregulated in many cancers and proposed to bind with both methylated- and unmethylated-DNA in the nucleus as a transcriptional repressor. The objective is to define its subcellular localization in vivo and exact binding DNA sequences in cells.


METHODS
Compartmentalization of exogenous Kaiso in cells was tracked with enhanced green fluorescence protein (EGFP) tag. The endogenous Kaiso expression in gastric carcinoma tissue was examined with immunohistochemical staining. Kaiso-DNA binding was tested using electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation assay (ChIP).


RESULTS
Kaiso mainly localized in the nucleus of cancer and stromal cells in vivo, but remained in the cytoplasm of cultured cells. Most importantly, nuclear Kaiso can bind with the methylated-CGCG-containing sequence in the CDKN2A promoter, but not with the hydroxymethylated-CGCG sequence in HCT116 cells.


CONCLUSIONS
Kaiso locates mainly in the nucleus in vivo where it binds with the methylated-CGCG sequences, but does not bind with the hydroxymethylated-CGCG sequences.
Beijing Key Laboratory of Carcinogenesis and Translational Research, Division of Cancer Etiology, Peking University Cancer Hospital & Institute, Beijing 100142, China.
Sisi
S
Qin
Beijing Key Laboratory of Carcinogenesis and Translational Research, Division of Cancer Etiology, Peking University Cancer Hospital & Institute, Beijing 100142, China.
Baozhen
B
Zhang
Beijing Key Laboratory of Carcinogenesis and Translational Research, Division of Cancer Etiology, Peking University Cancer Hospital & Institute, Beijing 100142, China.
Wei
W
Tian
Beijing Key Laboratory of Carcinogenesis and Translational Research, Division of Cancer Etiology, Peking University Cancer Hospital & Institute, Beijing 100142, China.
Liankun
L
Gu
Beijing Key Laboratory of Carcinogenesis and Translational Research, Division of Cancer Etiology, Peking University Cancer Hospital & Institute, Beijing 100142, China.
Zheming
Z
Lu
Beijing Key Laboratory of Carcinogenesis and Translational Research, Division of Cancer Etiology, Peking University Cancer Hospital & Institute, Beijing 100142, China.
Dajun
D
Deng
CDKN2A; DNA binding; Kaiso; compartmentalization; hydroxymethylation; methylation