Ultraconserved non-coding sequence element controls a subset of spatiotemporal GLI3 expression

Area of Science:

• Developmental Biology
• Genetics
• Molecular Biology

Background:

• The zinc-finger transcription factor GLI3 is essential for vertebrate development, mediating sonic hedgehog (SHH) signaling.
• Mutations in GLI3 cause GLI3-morphopathies, congenital disorders affecting forebrain and limb development.

Purpose of the Study:

• To identify and characterize a novel transcriptional enhancer element within the GLI3 gene.
• To investigate the regulatory role and evolutionary conservation of this enhancer in GLI3 gene expression.

Main Methods:

• Bioinformatic analysis to identify conserved non-coding elements in the GLI3 gene.
• Reporter gene assays (transient transfection) in human cell lines to test enhancer activity.
• In vivo studies using zebrafish and transgenic mouse embryos to assess tissue-specific expression patterns.

Main Results:

• A highly conserved non-coding element in intron two of GLI3 functions as a transcriptional enhancer.
• The enhancer activates reporter gene expression in GLI3-expressing cells, demonstrating GLI3-dependent regulation.
• Conserved transcription factor binding sites within the enhancer are predicted, suggesting a role in developmental regulation.
• The enhancer directs tissue-specific reporter gene expression in zebrafish and mouse embryos, mirroring endogenous GLI3 patterns.

Conclusions:

• A novel, evolutionarily conserved enhancer regulates GLI3 transcription during development.
• This enhancer plays a role in the spatiotemporal control of GLI3 expression, relevant to understanding GLI3-morphopathies.
• The findings provide insights into the regulatory mechanisms governing GLI3 function in development.