Download or read book PET-1 Switches Transcriptional Targets Postnatally to Regulate Maturation of Serotonin Neuron Excitability written by Steven Curtis Wyler and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The tremendous diversity of neuronal cell types enables the assembly of neural circuitry that generates and shapes complex behaviors. In contrast to the intense focus on understanding the gene regulatory programs that specify different neuron types, the programs that guide their maturation have received far less attention. Here we show the embryonic maturation of serotonergic (5-HT) neurons, and the role of the transcription factor, PET-1 in driving this maturational program. Initally we undertook a series of experiments to define PET-1's function in development and the early postnatal period. To this end, we used RNA-Seq in flow sorted fetal YFP+ 5-HT neurons obtained from the rostral hindbrain to identify specific temporal gene expression patterns found in maturing 5-HT neurons from E11.5 to shortly after birth (P1-P3). We found that genes downregulated from E11.5 to birth were genes associated with basic cellular processes, while genes upregulated were associated with maturing neural identity and function. Next we compared the expression profile of E15.5 +/+ and Pet-1-/- 5-HT neurons. Expression of over 800 genes was diminished 1.5-40 fold, and greater than 1000 genes were derepressed 1.5-13 fold in Pet-1-/- 5-HT neurons. Gene ontology shows that PET-1 is a regulator of diverse pathways including cell synaptic development and function, axon and dendrite development, and neural transmission. The role of PET-1's in driving maturation of genes involved in neuronal excitability was verified by single cell recording of 5-HT neurons. Aditionally, PET-1 was found to regulate the glutamatergic AMPA receptor subunit Gria4, the alpha adrenergic receptor 1b, Adra1b, and the lysophosphtidic acid receptor 1, Lpar1. This was verified by in situ hybridization, immunohistochemistry, and electorphysiological recordings. Finally, to ascertain PET-1's postnatal function, we deleted Pet-1 in the early postnatal period using the Cre/loxP system. This revealed PET-1 switches its focus on regulating genes needed for 5-HT synthesis to those needed for neuronal activity. Finally, we used ChIP-seq to identify PET-1 direct targets. We found PET-1 binds within or proximal to 25-30% of PET-1 upregulated and down regulated genes, suggesting direct transcriptional activation and repression of PET-1 is required for correct 5-HT development.