A novel function of OLIG2 to suppress human glial tumor cell growth via p27Kip1 transactivation

Abstract

Kip1 gene promoter was essential for OLIG2-dependent activation of p27Kip1 gene transcription. Electrophoretic mobility shift assays confirmed that a nuclear extract of OLIG2-expressing U12-1 cells contained a protein complex that binds to the CTF site of the p27 Kip1 gene promoter. Furthermore, siRNA against p27 Kip1 rescued the OLIG2-mediated growth and DNA synthesis inhibition of U12-1 cells. These results indicate that OLIG2 suppresses the proliferation of U12-1 and that this effect is mediated by transactivation of the p27 Kip1 gene, and low expression of OLIG2 may be related to the malignant behavior of human glioblastoma.

The Selective RNA-binding Protein Quaking I (QKI) Is Necessary and Sufficient for Promoting Oligodendroglia Differentiation

“…In fact, knocking down endogenous QKI did not affect p27Kip1 protein expression (Fig, 7D), indicating that QKI is not necessary for governing p27Kip1 expression in CG4 cells. It is important to point out that p27Kip1 expression is under sophisticated regulation by multi-ple molecular mechanisms at the levels of transcription, translation, and protein stability in addition to the stabilization of p27Kip1 mRNA by QKI (8,(35)(36)(37)(38). Therefore, compensatory mechanisms may prevent changes of p27Kip1 expression even when QKI is eliminated, which provides a possible explanation why QKI is unnecessary for p27Kip1 expression and cell cycle exit of CG4 cells (Fig.…”

Promoter hypomethylation regulates CD133 expression in human gliomas

“…The dual-luciferase reporter assay was performed as described previously [42]. Briefly, cells plated in 24-well plates were transiently transfected with the CD133 promoter-firefly luciferase plasmid and the internal control plasmid pRL-TK (Promega), which encodes Renilla luciferase and is used to normalize transfection efficacy.…”

Signaling adaptor protein Crk is indispensable for malignant feature of glioblastoma cell line KMG4

“…Soft-agar colony formation assay and xenograft propagation Soft-agar colony formation assay and xenograft propagation were carried out as described [22,23].. All animal procedures were performed according to the protocol approved by the institutional Animal…”