Modifying transcript lengths of cycling mouse segmentation genes.

Area of Science:

• Developmental Biology
• Molecular Genetics
• Chronobiology

Background:

• Somitogenesis, the formation of body segments, relies on a molecular oscillator known as the segmentation clock.
• This clock regulates cyclic gene transcription in the presomitic mesoderm (PSM).
• Key genes like Lunatic fringe (Lfng) and Hes7 are involved, but their precise roles in the primary oscillator remain unclear.

Purpose of the Study:

• To identify components of the primary segmentation clock oscillator.
• To investigate the role of transcriptional and post-transcriptional delays in controlling segmentation pace.
• To manipulate feedback circuitry delays in Lfng and Hes7 genes.

Main Methods:

• Generation of recombinant mice with lengthened introns in Lfng and Hes7 genes to delay mRNA production.
• Analysis of RNA splicing, gene expression, and somitogenesis in modified mice.
• Characterization of the effects of delayed gene expression on the segmentation clock.

Main Results:

• Lengthening the third Hes7 intron by 10 or 20 kb led to splicing defects and gene inactivation.
• In mice with a 10 kb Lfng intron lengthening, Lfng expression and activity remained normal.
• No significant effects on somitogenesis or segmentation were observed in Lfng-manipulated mice.

Conclusions:

• The study highlights the complex interplay of transcriptional and post-transcriptional delays in the segmentation clock.
• Hes7 intron lengthening demonstrates the critical role of proper splicing for gene function in somitogenesis.
• Further research is needed to fully elucidate the components and mechanisms of the primary segmentation clock oscillator.