Modular, cascade-like transcriptional program of regeneration in Stentor

Area of Science:

• Cell biology
• Developmental biology
• Regenerative medicine

Background:

• The giant ciliate Stentor coeruleus is a model organism for studying single-cell regeneration and morphogenesis.
• Regeneration of the oral apparatus or after bisection involves reproducible, transcription-dependent steps.

Purpose of the Study:

• To investigate dynamic transcriptome changes during Stentor regeneration using RNA sequencing (RNAseq).
• To identify gene expression modules and regulatory cascades involved in different regeneration events.
• To elucidate the roles of specific genes, such as Pumilio and E2F, in Stentor regeneration.

Main Methods:

• RNA sequencing (RNAseq) to analyze gene expression dynamics during oral apparatus regeneration and bisection.
• Blocking translation to investigate the cascade mechanism of gene expression waves.
• RNAi-mediated knockdown to assess the function of candidate regeneration regulators (Pumilio, E2F).

Main Results:

• Identified distinct temporal waves of gene expression, including kinases, RNA-binding proteins, and ciliopathy gene orthologs.
• Discovered specific gene expression modules for oral apparatus regeneration, holdfast regeneration, and wound recovery.
• Demonstrated that sequential gene expression waves are triggered by a cascade mechanism dependent on translation products.
• Pumilio is essential for correct oral structure size, while E2F is crucial for regeneration completion.

Conclusions:

• Regeneration in Stentor involves coordinated, sequential gene expression waves regulated by a post-transcriptional cascade.
• Pumilio and E2F are key regulators controlling specific phases and outcomes of regeneration.
• This study provides a framework for classifying regeneration genes and understanding cellular morphogenetic coordination.