Biomedical subjects

Kenji Kawamura

Publications and source records attributed to Kenji Kawamura.

40 records · Page 3Linked to original sources

PubMed2002

Chinese medicine induces neurite outgrowth in PC12 mutant cells incapable of differentiation.

During continuous culture of neural PC12 cells, we obtained a drug-hypersensitive PC12 mutant cell that showed high stimulation of neurite outgrowth by various drugs. When several Chinese medicines such as shu-jing-huo-xie-tang and Wu-Ling-San were provided to these PC12 mutant cells, the frequency of nerve growth factor (NGF)-induced neurite outgrowth increased approximately 30-fold compared to NGF alone. Neurite outgrowth induced by NGF in PC12 cells is accompanied by sustained activation of mitogen-activated protein kinase (MAPK); however, these Chinese medicines did not induce MAPK activity. The findings thus indicate that certain Chinese medicines may induce neurite outgrowth by a novel mechanism which is distinct from the NGF-activated pathway in PC12 mutant cells.

Animals↗

PubMed2002

Immunosuppressant FK506 induces sustained activation of MAP kinase and promotes neurite outgrowth in PC12 mutant cells incapable of differentiating.

During the continuous culturing of neural PC12 cells, a drug hypersensitive PC12 mutant cell line (PC12m3) was obtained, which demonstrated high neurite outgrowth when stimulated by various drugs. When the immunosuppressant drug FK506 and nerve growth factor (NGF) were introduced to the PC12m3 cells, the frequency of neurite outgrowth increased approximately 40-fold for NGF alone. However, the effect of FK506 on neuritogenesis in PC12 parental and drug insensitive PC12m1 mutant cells was much lower than in PC12m3 cells. The sustained activation of mitogen-activated protein (MAP) kinase plays an important role in neurite outgrowth of PC12 cells. Interestingly, the drug hypersensitive PC12m3 cells exhibited the sustained activation of MAP kinase with FK506 in comparison to low or no activities in PC12 parental or drug insensitive PC12m1 cells. These results indicate that PC12m3 cells have a novel FK506-induced MAP kinase pathway for neuritogenesis.

Animals↗

PubMed2002

Enhancing and suppressing effects of dexamethasone on transgene expression in vitro.

Gene therapy is becoming an important treatment modality against various diseases including cancer, genetic disorders, infectious diseases and inflammatory diseases. For achieving successful gene therapy, it is extremely important to control the expression of a transduced therapeutic gene. However, there have been few studies examining the effect of glucocorticoid on transgene expression. We demonstrate here that the synthetic glucocorticoid dexamethasone significantly affected transgene expression in vitro. Bone marrow cells freshly prepared from rats and murine fibroblasts were infected with retroviruses carrying the neomycin phosphotransferase gene under the transcriptional control of the retroviral long terminal repeat promoter and the reporter lacZ gene under the transcriptional control of the simian virus 40 (SV40) early promoter. Retrovirus-infected cells were selected by G418. When retrovirus-infected bone marrow cells were cultured in the presence of dexamethasone, lacZ expression was markedly decreased. This suppressive effect of dexamethasone on transgene expression in bone marrow cells appeared to be mediated by a methylation-independent mechanism, because the suppressive effect was also observed in bone marrow cells that were supposed to contain a considerable number of methylated cells. In marked contrast, when retrovirus-infected fibroblasts were cultured in the presence of dexamethasone, lacZ expression was significantly increased. The enhancing and suppressing effects of dexamethasone on transgene expression were considered to be independent on promoter types, because the SV40 early promoter used to control lacZ expression does not contain a glucocorticoid-responsive element. Therefore, the different effects of dexamethasone on transgene expression appeared to be dependent on cell types. These results indicate that dexamethasone may play an important role for achieving successful gene therapy. Furthermore, these observations may also have important implications for future clinical applications of gene therapy.

3T3 Cells↗

PubMedDate not supplied

Intracellular signal-responsive gene carrier for cell-specific gene expression.

We designed a peptide-polymer conjugate (CPCCtat) as a novel gene carrier that could control gene expression responding to the intracellular caspase-3 signal. This carrier consists of an uncharged main polymer chain and a cationic peptide side chain, which includes the substrate sequence of caspase-3 and the protein transduction domain sequence of HIV-1 Tat. In the present study, CPCCtat formed a tight complex with DNA through an electrostatic interaction, and in this state the gene expression was totally suppressed. In contrast, the complex disintegrated in the presence of caspase-3 due to cleavage of the cationic portion from CPCCtat. This event led to an activation of gene expression. Our results also indicate that the complex can be delivered into living cells due to the cell-permeable peptide side chain of CPCCtat. This intracellular signal-responsive system with CPCCtat will be useful for the cell-specific gene expression system.

Animals↗