Neuron-specific and developmental regulation of the synapsin II gene expression in transgenic mice

Synapsin II, a major phosphoprotein of synaptic vesicles, is believed to function in neurotransmitter release as well as in synapse formation. The expression of the synapsin II gene is neuron-specific, and correlates temporally with synaptogenesis. To understand the mechanisms by which the expression of the synapsin II gene is regulated in vivo, we generated transgenic mice carrying a 5.1-kb 5'-flanking sequence of the murine synapsin II gene fused to the firefly luciferase reporter gene. The synapsin II-luciferase transgene is specifically expressed in neural tissues, such as brain and spinal cord, but not in non-neural tissues. Throughout the brain, the expression of the transgene is widely distributed, and restricted only to neuronal cells. Moreover, the expression of the transgene is developmentally regulated, with a temporal profile similar to that of endogenous synapsin II expression. These results indicate that the 5.1-kb flanking sequence of the murine synapsin II gene contains cis-regulatory elements that are required for directing neuron-specific and synaptogenesis-regulated expression in vivo.