The Unkempt RNA-binding protein reveals a local translation program in centriole overduplication.

Abstract

Excess centrosomes cause defects in mitosis, cell-signaling, and cell migration, and therefore their assembly is tightly regulated. The divergent Polo kinase, PLK4, controls centriole duplication at the heart of centrosome assembly, and elevated PLK4 levels promote centrosome amplification (CA), a founding event of tumorigenesis. Here, we investigate the transcriptional consequences of elevated PLK4 and find Unkempt (UNK), a gene encoding an RNA-binding protein with roles in mRNA translational regulation, to be one of only two upregulated mRNAs. UNK protein localizes around centrosomes and with CEP131-positive centriolar satellites, promoting CEP131 localization to and around centrosomes. UNK's RNA-binding activity is required for PLK4-induced centriole overduplication. Consistent with the loss in PLK4-induced centriole overduplication, UNK depletion disrupts PLK4 and centriole assembly protein localization. Finally, translation is enriched at centrosomes and centriolar satellites, with UNK and CEP131 promoting this localized translation. In summary, UNK and CEP131 promote PLK4 localization and local translation at centrosomes during centriole overduplication.