Effect of N1-acetylspermidine treatment on the translatome of hair follicle stem cell organoid cultures

Stem cell differentiation has been shown to involve an increase in mRNA translation. Amongst others, the rate of translation is influenced by availability of the natural polyamines putrescine, spermidine, and spermine that are essential for cell growth and modulate stem cell maintenance. However, the link between polyamines and translation in cell fate decisions remains obscure. Here, we used hair follicle stem cell (HFSC) organoids to study the role of polyamines as key regulators of mRNA translation in stem cell fate decisions. HFSCs showed lower translation and reduced polyamine levels than progenitor cells. Surprisingly, we found that reduced translation achieved by changed polyamine availability and stemness do not correlate in the organoids. We identified N1-acetylspermidine as regulator of cell fate decisions. To investigate the effect on translation upon N1-AcSpd supplementation, we performed ribosome foot pronting. We confirmed the increase in proliferation identified by 3'RNA-sequencing on the translatome level. N1-AcSpd treatment partially aligns the translatome of progenitor cells to that of HFSCs. Overall, this study delineates the diverse routes of polyamine metabolism-mediated regulation of stem cell fate decisions.