Effect of N1-acetylspermidine treatment on 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 than progenitor cells, and a forced suppression of translation by direct targeting of the ribosome or through specific depletion of natural polyamines elevated stemness. In addition, we identified N1-acetylspermidine as a novel parallel regulator of cell fate decisions. To identify the molecular mechanism by which N1-AcSpd supplementation promotes stemness, we performed RNA-sequencing. We unravel an increase in proliferation. Overall, this study delineates the diverse routes of polyamine metabolism-mediated regulation of stem cell fate decisions.