[Gene expression and cellular function]

During the development of vertebrates, differentiated cells are already programmed to synthesize functional proteins to express their specified cellular functions by receiving several kinds of extracellular signals. By use of the in vitro and in vivo systems for analyzing the molecular mechanisms of antibody synthesis in B-lymphocytes, I have found that an activation of immunoglobulin gene could be involved in the activation of antibody synthesis induced by antigen signals. By developing the cell-free transcriptional systems of silk fibroin gene, I have subsequently found that the gene activation could mainly be achieved by the interactions between the defined nucleotide sequences located upstream from the TATA box of the gene and transcriptional factors which can specifically bind to these upstream sequences. To understand an exact role of neuronal cells in the generation of synaptic plasticity, I am now investigating the genetical responses of neuronal cells activated by synaptic transmission. Elucidation of the gene products whose expression could be affected by the synaptic transmission would reveal functional aspects of neuronal cells when they receive several kinds of synaptic inputs. By use of the primary culture of mouse cerebellar granule cells, we have already revealed several aspects of intracellular mechanisms responsible for the glutamatergic responses of the neuronal cells, focusing on an activation of transcriptional factors whose expression could be immediately induced by the glutamatergic inputs. This type of experiments would provide a valuable insight for understanding the cellular and the molecular mechanisms of synaptic plasticity.