van den Berg, L., Kokki, K., Wowro, S.J., Petricek, K.M., Deniz, O., Stegmann, C.A., Robciuc, M., Teesalu, M., Melvin, R.G., Nieminen, A.I., Schupp, M., Hietakangas, V. (2023). Sugar-responsive inhibition of Myc-dependent ribosome biogenesis by Clockwork orange.  Cell Rep. 42(7): 112739.

FBrf0257174

Research paper

The ability to feed on a sugar-containing diet depends on a gene regulatory network controlled by the intracellular sugar sensor Mondo/ChREBP-Mlx, which remains insufficiently characterized. Here, we present a genome-wide temporal clustering of sugar-responsive gene expression in Drosophila larvae. We identify gene expression programs responding to sugar feeding, including downregulation of ribosome biogenesis genes, known targets of Myc. Clockwork orange (CWO), a component of the circadian clock, is found to be a mediator of this repressive response and to be necessary for survival on a high-sugar diet. CWO expression is directly activated by Mondo-Mlx, and it counteracts Myc through repression of its gene expression and through binding to overlapping genomic regions. CWO mouse ortholog BHLHE41 has a conserved role in repressing ribosome biogenesis genes in primary hepatocytes. Collectively, our data uncover a cross-talk between conserved gene regulatory circuits balancing the activities of anabolic pathways to maintain homeostasis during sugar feeding.