NF-Y activates mouse tryptophan hydroxylase transcription

Area of Science:

• Molecular Biology
• Neuroscience
• Genetics

Background:

• Serotonin (5-HT) is a key neurotransmitter implicated in psychiatric disorders.
• Tryptophan hydroxylase (TPH) catalyzes the rate-limiting step in serotonin biosynthesis.
• The tissue-specific transcriptional regulation of TPH is not well understood.

Purpose of the Study:

• To investigate the transcriptional regulation of the tryptophan hydroxylase gene.
• To identify transcription factors involved in controlling TPH expression.

Main Methods:

• Analysis of 5'-deletion constructs of TPH promoter-reporter plasmids in P815-HTR mastocytoma cells.
• DNase I footprinting and gel shift assays to identify protein-DNA interactions.
• Methylation interference analysis and site-directed mutagenesis to characterize binding sites and their functional significance.

Main Results:

• Transcriptional activity was regulated by sequences between nucleotides -343 and -21 of the TPH promoter.
• DNase I footprinting identified a protein-DNA interaction between nucleotides -77 and -46.
• This binding site corresponds to an inverted GGCCAAT element, a high-affinity motif for the transcription factor NF-Y.
• Mutagenesis of the NF-Y binding site significantly decreased transcriptional activity (65%).

Conclusions:

• The transcription factor NF-Y binds to a specific GGCCAAT motif in the proximal promoter of the tryptophan hydroxylase gene.
• NF-Y binding to this motif activates TPH gene transcription.
• This finding provides insight into the molecular mechanisms regulating serotonin biosynthesis.