LAUSR

Metabolic pathway regulates cell fate Lineage-specific regulators direct cell fate decisions, but the precise mechanisms are not well known. Using an in vivo chemical suppressor screen of a bloodless zebrafish mutant, Rossmann et al. show that the lineage-specific chromatin factor tif1γ directly regulates mitochondrial genes to drive red blood cell differentiation. Loss of tif1γ reduces coenzyme Q synthesis and function, impeding mitochondrial respiration and leading to epigenetic alterations and repression of erythropoiesis. The loss of blood in the mutant fish can be rescued by the addition of coenzyme Q. This work establishes a mechanism by which a chromatin factor tunes a metabolic pathway in a tissue-specific manner. Science, this issue p. 716 Mitochondrial metabolism is controlled by a lineage transcription factor that drives cell fate decisions in the early blood lineage in zebrafish. Transcription and metabolism both influence cell function, but dedicated transcriptional control of metabolic pathways that regulate cell fate has rarely been defined. We discovered, using a chemical suppressor screen, that inhibition of the pyrimidine biosynthesis enzyme dihydroorotate dehydrogenase (DHODH) rescues erythroid differentiation in bloodless zebrafish moonshine (mon) mutant embryos defective for transcriptional intermediary factor 1 gamma (tif1γ). This rescue depends on the functional link of DHODH to mitochondrial respiration. The transcription elongation factor TIF1γ directly controls coenzyme Q (CoQ) synthesis gene expression. Upon tif1γ loss, CoQ levels are reduced, and a high succinate/α-ketoglutarate ratio leads to increased histone methylation. A CoQ analog rescues mon’s bloodless phenotype. These results demonstrate that mitochondrial metabolism is a key output of a lineage transcription factor that drives cell fate decisions in the early blood lineage.