Neuron-specific gene expression of synapsin I. Major role of a negative regulatory mechanism.
The synapsins are a family of neuron-specific phosphoproteins that selectively bind to small synaptic vesicles in the presynaptic nerve terminal. The human synapsin I gene was functionally analyzed to identify control elements directing the neuron-specific expression of synapsin I. By directly measuring the mRNA transcripts of a reporter gene, we demonstrate that the proximal region of the synapsin I promoter is sufficient for directing neuron-specific gene expression. This proximal region is highly conserved between mouse and human. Deletion of a putative binding site for the zinc finger protein, neuron-restrictive silencer factor/RE-1 silencing transcription factor (NRSF/REST), abolished neuron-specific expression of the reporter gene almost entirely, allowing constitutively acting elements of the promoter to direct expression in a non-tissue-specific manner. These constitutive transcriptional elements are present as a bipartite enhancer, consisting of the region upstream (nucleotides -422 to -235) and downstream (nucleotides -199 to -143) of the putative NRSF/REST-binding site. The latter contains a motif identical to the cAMP response element. Both regions are not active or are only weakly active in promoting transcription on their own and show no tissue-specific preference. From these data we conclude that neuron-specific expression of synapsin I is accomplished by a negative regulatory mechanism via the NRSF/REST binding motif.
Schoch
S
S
Institute for Genetics, University of Cologne, D-50674 Cologne, Federal Republic of Germany.
Cibelli
G
G
Thiel
G
G
D000818:Animals; D001483:Base Sequence; D016466:CHO Cells; D017124:Conserved Sequence; D006224:Cricetinae; D004742:Enhancer Elements, Genetic; D005786:Gene Expression Regulation; D005914:Globins / Q000096:biosynthesis; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009474:Neurons / Q000378:metabolism*; D015345:Oligonucleotide Probes; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000096:biosynthesis; D012045:Regulatory Sequences, Nucleic Acid; D012689:Sequence Homology, Nucleic Acid; D016704:Synapsins / Q000096:biosynthesis* / Q000235:genetics*; D016385:TATA Box; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured; D016335:Zinc Fingers
D015345:Oligonucleotide Probes; D012333:RNA, Messenger; D016704:Synapsins; D005914:Globins