Masanobu Kitagawa

Learn More
A 42 kb region on human chromosome 9p21 encodes for three distinct tumor suppressors, p16(INK4A), p14(ARF) and p15(INK4B), and is altered in an estimated 30-40% of human tumors. The expression of the INK4A-ARF-INK4B gene cluster is silenced by polycomb during normal cell growth and is activated by oncogenic insults and during aging. How the polycomb is(More)
The ubiquitin-proteasome pathway plays an important role in control of the abundance of cell cycle regulators. Mice lacking Skp2, an F-box protein and substrate recognition component of an Skp1-Cullin-F-box protein (SCF) ubiquitin ligase, were generated. Although Skp2(-/-) animals are viable, cells in the mutant mice contain markedly enlarged nuclei with(More)
Plasmids that can be used for controlled expression of the DnaK-DnaJ-GrpE and/or GroEL-GroES chaperone team were constructed in order to facilitate assessment of the effects of these chaperone teams on folding or assembly or recombinant proteins in Escherichia coli. A typical pACYC184-based plasmid which was obtained could express the major DnaK-DnaJ-GrpE(More)
The association of the p27(Kip1) protein with cyclin and cyclin-dependent kinase complexes inhibits their kinase activities and contributes to the control of cell proliferation. The p27(Kip1) protein has now been shown to be phosphorylated in vivo, and this phosphorylation reduces the electrophoretic mobility of the protein. Substitution of Ser(10) with Ala(More)
Interferon regulatory factor 1 (IRF-1), a transcriptional activator, and its antagonistic repressor, IRF-2, were originally identified as regulators of the type I interferon (IFN) system. We have generated mice deficient in either IRF-1 or IRF-2 by gene targeting in embryonic stem cells. IRF-1-deficient fibroblasts lacked the normally observed type I IFN(More)
Development of an analytical method for polybrominated diphenyl ethers (PBDEs) in fish and their concentration in Japanese marine fish were investigated. Fish homogenate was extracted with diethyl ether/hexane (1 + 3). The extract was cleaned up by automated gel permeation chromatography (GPC) and then by mini-column chromatography, which consisted of three(More)
Of 17 cases of small cell carcinoma of the stomach, three were early and 14 were advanced. Grossly, the tumors were mostly polypoid at the early stage, and as they advanced, deep ulcerations developed. Histologically, only one tumor was "oat cell type," and the other 16 were "intermediate cell type." With regard to tumor components, five were "pure" tumor,(More)
Interferon regulatory factor-1 (IRF-1), a transcriptional activator, and IRF-2, its antagonistic repressor, have been identified as regulators of type I interferon and interferon-inducible genes. The IRF-1 gene is itself interferon-inducible and hence may be one of the target genes critical for interferon action. When the IRF-2 gene was overexpressed in NIH(More)
Cyclin D-Cdk4/6 and cyclin A/E-Cdk2 are suggested to be involved in phosphorylation of the retinoblastoma protein (pRB) during the G1/S transition of the cell cycle. However, it is unclear why several Cdks are needed and how they are different from one another. We found that the consensus amino acid sequence for phosphorylation by cyclin D1-Cdk4 is(More)
The transcriptional activator interferon regulatory factor 1 (IRF-1) and its antagonistic repressor IRF-2 are regulators of the interferon (IFN) system and of cell growth. Here we report that embryonic fibroblasts (EFs) from mice with a null mutation in the IRF-1 gene (IRF-1-/- mice) can be transformed by expression of an activated c-Ha-ras oncogene. This(More)