The NF-Y complex negatively regulates Caenorhabditis elegans tbx-2 expression

Area of Science:

• Developmental Biology
• Gene Regulation
• Molecular Biology

Background:

• T-box genes play crucial roles in animal development but their expression mechanisms are poorly understood.
• The Caenorhabditis elegans T-box gene tbx-2 is vital for pharyngeal muscle development, neural cell fate, and olfactory adaptation.
• tbx-2 exhibits complex expression patterns during embryogenesis and in adult sensory neurons.

Purpose of the Study:

• To investigate the regulatory mechanisms controlling tbx-2 gene expression.
• To identify transcription factors that modulate tbx-2 activity.
• To elucidate the role of the Nuclear Factor Y (NF-Y) complex in tbx-2 regulation.

Main Methods:

• RNA interference (RNAi) screen of transcription factor genes using a Ptbx-2::gfp reporter strain.
• Analysis of NF-Y subunits (nfya-1, nfyb-1, nfyc-1) using RNAi and mutant strains.
• Site-directed mutagenesis of CCAAT-boxes within the tbx-2 promoter.
• Quantitative analysis of tbx-2 mRNA levels in nfya-1 null mutants.
• Identification and characterization of a second-site mutation in nfyb-1.

Main Results:

• The Nuclear Factor Y (NF-Y) complex was identified as a negative regulator of tbx-2 expression.
• Loss of NF-Y subunits (nfya-1, nfyb-1, nfyc-1) resulted in ectopic Ptbx-2::gfp expression in hypodermal seam cells and gut.
• Mutation of CCAAT-boxes in the tbx-2 promoter mimicked the ectopic expression pattern, indicating direct repression by NF-Y.
• tbx-2 mRNA levels were moderately increased in nfya-1 null mutants.
• A deletion in the nfyb-1 gene was identified as a second-site mutation enhancing the lethality of a tbx-2 mutant.

Conclusions:

• NF-Y directly represses tbx-2 gene expression by binding to CCAAT-boxes in its promoter.
• NF-Y plays a significant role in regulating tbx-2 function during Caenorhabditis elegans development.
• These findings provide new insights into the transcriptional control of T-box genes.