Ptf1a, along with an E protein and Rbpj, forms the transcription factor complex PTF1-J that is essential for proper specification of inhibitory neurons in the spinal cord, retina, and cerebellum. Here we show that two highly conserved noncoding genomic regions, a distal 2.3 kb sequence located 13.4 kb 5′ and a 12.4 kb sequence located immediately 3′ of the Ptf1a coding region, have distinct activity in controlling Ptf1a expression in all of these domains. The 5′ 2.3 kb sequence functions as an autoregulatory element and directs reporter gene expression to all Ptf1a domains in the developing nervous system. The autoregulatory activity of this element was demonstrated by binding of the PTF1-J complex in vitro, Ptf1a localization to this genomic region in vivo, and the in vivo requirement of Ptf1a for the activity of the regulatory element in transgenic mice. In contrast, the 12.4 kb 3′ regulatory region does not contain any conserved PTF1 sites, and its expression in transgenic mice is independent of Ptf1a. Thus, regulatory information for initiation of Ptf1a expression in the developing nervous system is located within the 12.4 kb sequence 3′ of the Ptf1a gene. Together, these results identify multiple transcriptional mechanisms that control Ptf1a levels, one modulating levels by autoregulation through the PTF1-J complex, and the other a Ptf1a-independent mechanism for initial activation.
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