miRNAs cooperate in apoptosis regulation during C. elegans development

Area of Science:

• Developmental Biology
• Molecular Biology
• Genetics

Background:

• Programmed cell death is crucial for development in Caenorhabditis elegans.
• The gene egl-1 encodes a proapoptotic BH3-only protein, regulating cell death.
• MicroRNAs (miRNAs) are key regulators of gene expression.

Purpose of the Study:

• To investigate the role of miR-35 and miR-58 in regulating programmed cell death during C. elegans embryogenesis.
• To elucidate the mechanism by which these miRNAs control the expression of the proapoptotic gene egl-1.

Main Methods:

• Analysis of miRNA binding sites in the egl-1 3' untranslated region (UTR).
• Measurement of mRNA copy number and translation efficiency.
• Single-molecule RNA fluorescent in situ hybridization (smRNA FISH) to visualize egl-1 transcription.

Main Results:

• miR-35 and miR-58 repress egl-1, preventing precocious death of mother cells.
• Repression involves binding sites in the egl-1 3' UTR, affecting mRNA levels and translation.
• miRNAs maintain egl-1 mRNA below a critical threshold in mother cells and dampen its transcription in daughter cells.

Conclusions:

• miR-35 and miR-58 act as crucial regulators of programmed cell death in C. elegans.
• These miRNAs ensure precise control of egl-1 expression, allowing cell death only in designated daughter cells.
• miRNAs compensate for variations in egl-1 transcription to achieve developmental accuracy.