Protein phosphatase-1 (PP1) nuclear targeting subunit (PNUTS), also called PP1R10, p99, or CAT 53 was originally isolated as a mammalian nuclear PP1-binding protein. In this study, we performed yeast two-hybrid screens to identify PNUTS-interacting proteins. Here, we report that LCP1 (epidermal Langerhans cell protein 1), a novel member of the HMG-box protein family, binds tightly to PNUTS. Co-immunoprecipitation of deletion constructs revealed that the C-terminus of LCP1 is sufficient for the interaction with an N-terminal region of PNUTS that is distinct from its PP1-binding domain. Furthermore, immunofluorescence studies showed that a subpopulation of LCP1 co-localizes with PNUTS in nuclear speckles. Importantly, we found that the N-terminus of LCP1 has a strong trans-activation activity in a GAL4-based heterologous transcription assay. The transcriptional activity of LCP1 is markedly suppressed by its interaction with PNUTS, in a PP1-independent manner. These findings suggest that the coordinated spatial and temporal regulation of LCP1 and PNUTS may be a novel mechanism to control the expression of genes that are critical for certain physiological and pathological processes.
Amino Acid Sequence ; Cell Line ; Cell Nucleus/*metabolism ; DNA-Binding Proteins/*metabolism ; HMGB Proteins/*metabolism ; Humans ; Molecular Sequence Data ; Nuclear Proteins/*metabolism ; Protein Binding ; Protein Interaction Mapping ; RNA-Binding Proteins/*metabolism ; Transcriptional Activation ; Two-Hybrid System Techniques

OBJECTIVETo investigate the association between high mobility group box1 (HMGB1) and cervical squamous cell carcinoma (CSCC), and explore the role of HMGB1/RAGE pathway in the metastasis of CSCC.

METHODSLevels of HMGB1 mRNA and RAGE mRNA in CSCC and normal cervical tissues were detected by real time quantitative polymerase chain reaction (qRT-PCR), and the level of HMGB1 protein was determined by immunohistochemistry and Western blotting.

RESULTSThe mRNA and protein expression of HMGB1 was significantly higher in CSCC than that in normal cervical tissue (P < 0.05), correlated with stage, invasion and metastasis (P < 0.05), but not with tumor size and differentiation (P > 0.05). The levels of RAGE mRNA and HMGB1 mRNA were both significantly higher (r = 0.663, P < 0.05) in metastatic CSCC in comparison with those in the non-metastatic cases.

CONCLUSIONHMGB1 is involved in the invasion and metastasis of CSCC, and HMGB1/RAGE pathway plays an important role in the metastasis of CSCC.

Blotting, Western ; Carcinoma in Situ ; metabolism ; pathology ; Carcinoma, Squamous Cell ; metabolism ; pathology ; Cervix Uteri ; metabolism ; pathology ; Female ; Gene Expression Regulation, Neoplastic ; HMGB Proteins ; metabolism ; Humans ; Immunohistochemistry ; Lymphatic Metastasis ; Neoplasm Invasiveness ; Neoplasm Metastasis ; Neoplasm Staging ; RNA, Messenger ; metabolism ; Receptor for Advanced Glycation End Products ; Receptors, Immunologic ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Signal Transduction ; Uterine Cervical Neoplasms ; metabolism ; pathology