RNA Sequencing of Stentor Cell Fragments Reveals Transcriptional Changes during Cellular Regeneration

While ciliates of the genus Stentor are known for their ability to regenerate when their cells are damaged or even fragmented, the physical and molecular mechanisms underlying this process are poorly understood. To identify genes involved in the regenerative capability of Stentor cells, RNA sequencing of individual Stentor polymorphus cell fragments was performed. After splitting a cell over the anterior-posterior axis, the posterior fragment has to regenerate the oral apparatus, while the anterior part needs to regenerate the hold fast. Altogether, differential expression analysis of both posterior and anterior S. polymorphus cell fragments for four different post-split time points revealed over 10,000 upregulated genes throughout the regeneration process. Among these, genes involved in cell signaling, microtubule-based movement, and cell cycle regulation seemed to be particularly important during cellular regeneration. We identified roughly nine times as many upregulated genes in regenerating S. polymorphus posterior fragments as compared to anterior fragments, indicating that regeneration of the anterior oral apparatus is a complex process that involves many genes. Our analyses identified several expanded groups of genes, such as dual-specific tyrosine-(Y)-phosphorylation-regulated kinases and MORN domain-containing proteins that seemingly act as key regulators of cellular regeneration. In agreement with earlier morphological and cell biological studies [1, 2], our differential expression analyses indicate that cellular regeneration and vegetative division share many similarities.