A Mechanistic Study Of How Syk Inhibitor R406 Promotes Chemical Reprogramming Of Mouse Somatic Cells

Pluripotent stem cells(PSCs)can self-renew and differentiate into cells of all three germ layers.Somatic cells can be induced into PSCs via nuclear transfer into oocytes,cell fusion with stem cells,the ectopic expression of transcription factors or treatment with chemical compounds.Small molecules are more convenient,don't integrate into chromosomes,and can provide a better understanding of cell-fate transitions.However,chemical induced pluripotent reprogramming is still time-consuming and labor-intensive.Here we screened about 600 compounds,and identified R406 that could significantly increase reprogramming efficiency.Mechanistically,R406 regulated reprogramming through Syk-calcineurin-NFAT signaling pathway.Using RNA-seq,we found that R406 increased the expression of glycine-serine-threonine metabolic genes,and CUT&Tag experiment revealed that NFATc1 was a direct repressor of these genes.Through Quasi-Targeted Metabolomics and LC-MS,we found that R406 increased the levels of metabolites in glycine-serine-threonine metabolism,transsulfuration pathway,and cysteine metabolism,which in turn increased the synthesis of H₂S.The accumulated H₂S downregulated oxidative phosphorylation(OXPHOS)and ROS levels,facilitating chemical reprogramming.In summary,we identified that Syk inhibitor R406 significantly promoted chemical reprogramming,and revealed a novel mechanism of somatic cell reprogramming.