Synaptophysin, one of the major proteins on synaptic vesi-cles, is ubiquitously expressed throughout the brain. Syn-aptophysin and synapsin I, another synaptic vesicle protein, are also expressed by retinoic acid-induced neuronally dif-ferentiated P19 teratocarcinoma cells. Here, we show that inhibition of histone deacetylase activity in P19 cells is suf-ficient to activate transcription of the synaptophysin and synapsin I genes, indicating that neuronal differentiation and impairment of histone deacetylases results in a similar gene expression pattern
