CDK8 and CDK19 act redundantly to control the CFTR pathway in the intestinal epithelium

Abstract

CDK8 and CDK19 form a conserved cyclin‐dependent kinase subfamily that interacts with the essential transcription complex, Mediator, and also phosphorylates the C‐terminal domain of RNA polymerase II. Cells lacking either CDK8 or CDK19 are viable and have limited transcriptional alterations, but whether the two kinases redundantly control cell proliferation and differentiation is unknown. Here, we find in mice that CDK8 is dispensable for regulation of gene expression, normal intestinal homeostasis, and efficient tumourigenesis, and is largely redundant with CDK19 in the control of gene expression. Their combined deletion in intestinal organoids reduces long‐term proliferative capacity but is not lethal and allows differentiation. However, double‐mutant organoids show mucus accumulation and increased secretion by goblet cells, as well as downregulation of expression of the cystic fibrosis transmembrane conductance regulator (CFTR) and functionality of the CFTR pathway. Pharmacological inhibition of CDK8/19 kinase activity in organoids and in mice recapitulates several of these phenotypes. Thus, the Mediator kinases are not essential for cell proliferation and differentiation in an adult tissue, but they cooperate to regulate specific transcriptional programmes. image The Mediator kinases CDK8 and CDK19 are dispensable for intestinal cell proliferation and differentiation, but they cooperate to regulate cell lineage‐specific programs. In the intestinal epithelium, their loss of function promotes mucus production and secretion. Mice with an intestinal CDK8 knockout have a normal phenotype CDK8 and CDK19 are dispensable for intestinal cell proliferation and differentiation CDK8 and CDK19 are largely redundant in transcriptional control Loss of CDK8 and CDK19 in the intestine downregulates CFTR and causes a cystic fibrosis‐like phenotype