Toshio Kuroki

Publications (2)0 Total impact

• Article: Cloning from a mouse osteoblastic cell line of a set of transforming‐growth‐factor‐β1‐regulated genes, one of which seems to encode a follistatin‐related polypeptide

  Motoko SHIBANUMA, Jun'ichi MASHIMO, Akira MITA, Toshio KUROKI, Kiyoshi NOSE
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  ABSTRACT: Transforming growth factor(TGF)β1 is a potent inhibitor of growth in mouse osteoblastic MC3T3-E1 cells. To isolate genes that are induced by TGFβ1, the differential screening method was adopted using a cDNA library constructed from cells treated with TGFβ1 for 4 h. Six independent cDNA clones were isolated (TGFβ-stimulated clone, TSC-5, TSC-36, TSC-115, TSC-128, TSC-160 and TSC-161), the expression of which was increased by TGFβ1-treatment with maximal expression at 6–10 h. The steady-state levels of TSC-36, TSC-128 and TSC-160 increased almost tenfold, whereas those of TSC-5, TSC-115 and TSC-161 were elevated at most threefold. From partial nucleotide sequences, TSC-160 was found to be identical to rrg (ras-recision gene, lysyl oxydase), and TSC-115 had 80% similarity with tropomyosin cDNA, whereas other genes seemed novel. Expression of TSC-36 and TSC-160 was dramatically decreased in v-Ki-ras-transformed MC3T3 cells or in transformed NIH 3T3 cells (DT), and was recovered to normal levels in a flat revertant (C11). A nearly full-length copy of TSC-36 cDNA was isolated, and an open reading frame indicated that it encodes a protein of 35 kDa. An antiserum was raised against the C-terminal peptide predicted from the nucleotide sequence, and a polypeptide with an approximate molecular mass of 38 kDa was detected in cultured medium of MC3T3-E1 cells. The amino acid sequence of TSC-36 protein was found to have some similarity with follistatin, an activin-binding protein, and a limited similarity with the secreted protein rich in cysteine (SPARC).
  European Journal of Biochemistry. 09/1993; 217(1):13 - 19.
• Article: Inhibition by N-acetyl-l-cysteine of interleukin-6 mRNA induction and activation of NFκB by tumor necrosis factor α in a mouse fibroblastic cell line, Balb/3T3

  Motoko Shibanuma, Toshio Kuroki, Kiyoshi Nose
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  ABSTRACT: Redox-based modulation plays a role in transcriptional control of gene expression. In the present study, we investigated the possible role of reactive oxygen species in the induction of interleukin-6 (IL-6) mRNA and in increases in NFκB binding activity by tumor necrosis factor (TNF) α using a mouse fibroblastic cell line, Balb/3T3. Expression of IL-6 mRNA is known to be dependent upon NFκB that binds to the 5′-flanking region of the IL-6 gene. We found that: (i) TNFα increased IL-6 mRNA levels and this increase was inhibited by N-acetyl-l-cysteine (NAC), a scavenger of reactive oxygen species. (ii) NFκB binding activity in this cell line was also increased by TNFα, and the increase was inhibited in the presence of NAC. (iii) The treatment of cells with low doses of hydrogen peroxide increased the NFκB binding activity. (iv) Expression of a reporter gene in which the chloramphenicol acetyltransferase (CAT) gene was under the control of NFκB binding sites was induced by hydrogen peroxide. These results suggest that the induction of IL-6 mRNA is regulated by a mechanism involving reactive oxygen species and that NFκB, whose activity is sensitive to the cellular redox state, plays an important role in this induction in a fibroblastic cell line, Balb/3T3, stimulated with TNFα.
  FEBS Letters.