High mobility group box-1 is phosphorylated by protein kinase C zeta and secreted in colon cancer cells

Journal Article · Fri Jul 27 04:00:00 EDT 2012 · Biochemical and Biophysical Research Communications

DOI:https://doi.org/10.1016/J.BBRC.2012.06.116· OSTI ID:22210158

Lee, Hanna; Park, Minhee; Shin, Nara; Kim, Gamin ^[1]; Kim, Yun Gi ^[2]; Shin, Jeon-Soo ^[3]; Kim, Hoguen ^[1]

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1. Department of Pathology, Yonsei University College of Medicine, 134 Shinchon-Dong, Seodaemoon-Ku, Seoul (Korea, Republic of)
2. Department of Internal Medicine, Seoul National University College of Medicine, 28 Yongon-dong, Chongno-gu, Seoul 110-744 (Korea, Republic of)
3. Department of Microbiology, Yonsei University College of Medicine, 134 Shinchon-Dong, Seodaemoon-Ku, Seoul (Korea, Republic of)

Highlights: Black-Right-Pointing-Pointer Specific enzyme for HMGB1 phosphorylation and its secretion is proposed. Black-Right-Pointing-Pointer Inhibition of PKC-{zeta} leads to significant reduction of the secreted HMGB1. Black-Right-Pointing-Pointer Phosphorylation of specific site of HMGB1 redirects its secretion in cancer cells. Black-Right-Pointing-Pointer Activation of PKC-{zeta} in cancers explains the enhanced HMGB1 secretion. -- Abstract: High mobility group box-1 (HMGB1), a nuclear protein, is overexpressed and secreted in cancer cells. Phosphorylation on two different nuclear localization signal regions are known to be important for the nuclear-to-cytoplasmic transport and secretion of HMGB1. However, little is known about the biochemical mechanism of HMGB1 modifications and its subsequent secretion from cancer cells. To identify the specific enzyme and important sites for HMGB1 phosphorylation, we screened the protein kinase C (PKC) family in a colon cancer cell line (HCT116) for HMGB1 binding by pull-down experiments using a 3XFLAG-HMGB1 construct. Strong interactions between atypical PKCs (PKC-{zeta}, {lambda}, and {iota}) and cytoplasmic HMGB1 were observed in HCT116 cells. We further identified the most critical PKC isotype that regulates HMGB1 secretion is PKC-{zeta} by using PKC inhibitors and siRNA experiments. The serine residues at S39, S53 and S181 of HMGB1 were related to enhancing HMGB1 secretion. We also demonstrated overexpression and activation of PKC-{zeta} in colon cancer tissues. Our findings suggest that PKC-{zeta} is involved in the phosphorylation of HMGB1, and the phosphorylation of specific serine residues in the nuclear localization signal regions is related to enhanced HMGB1 secretion in colon cancer cells.

• OSTI ID: 22210158
• Journal Information: Biochemical and Biophysical Research Communications, Journal Name: Biochemical and Biophysical Research Communications Journal Issue: 2 Vol. 424; ISSN BBRCA9; ISSN 0006-291X
• Country of Publication: United States
• Language: English

Related Subjects

60 APPLIED LIFE SCIENCES
ANIMAL TISSUES
CARCINOMAS
ENZYMES
LARGE INTESTINE
PHOSPHORYLATION
SECRETION
SERINE
STRONG INTERACTIONS