Vitamin B12 is a limiting factor for in vivo reprogramming

Reprogramming in vivo using OCT4, SOX2, KLF4 and MYC (OSKM) triggers cell dedifferentiation, which is considered of relevance for tissue repair and regeneration. However, little is known about the metabolic requirements of this process. We found that antibiotic depletion of the gut microbiota abolished in vivo reprogramming. Analysis of bacterial metagenomes from stool samples of wild type (WT) and OSKM mice treated with doxycycline led us to identify vitamin B12 as a key factor for in vivo reprogramming, which is partly supplied by the microbiome. We report that B12 demand increases during reprogramming due to enhanced expression of enzymes in the methionine cycle, and supplementing B12 levels both in vitro and in vivo enhances the efficiency of OSKM reprogramming. Overall design: Examination of metagenomes from stool samples of mice expressing doxycycline inducible Oct4, Sox2, Klf4, c-Myc (OSKM) induced for 7 days and wild type (WT) mice treated with doxycycline.