Germline mutations in the PAF1 complex gene CTR9 predispose to Wilms tumour

Abstract

Wilms tumour is a childhood kidney cancer. Here we identify inactivating CTR9 mutations in 3 of 35 Wilms tumour families, through exome and Sanger sequencing. By contrast, no similar mutations are present in 1,000 population controls (P<0.0001). Each mutation segregates with Wilms tumour in the family and a second mutational event is present in available tumours. CTR9 is a key component of the polymerase-associated factor 1 complex which has multiple roles in RNA polymerase II regulation and is implicated in embryonic organogenesis and maintenance of embryonic stem cell pluripotency. These data establish CTR9 as a Wilms tumour predisposition gene and suggest it acts as a tumour suppressor gene.

Figure 1. Germline CTR9 mutations in familial Wilms tumour.

(a) Pedigrees of three Wilms tumour families with germline CTR9 mutations. The age at diagnosis and mutation are shown under the relevant individuals. (b) Sequencing chromatograms showing mutations in blood and tumour DNA and corresponding wild-type sequence from a control.

Figure 2. Splicing CTR9 mutations cause in-frame deletion of CTR9 TPR domains.

(a) Sequencing chromatograms from Reverse Transcription-PCR analysis of RNA from HEK293 cells, transiently transfected with CTR9 minigene splicing constructs containing the c.1194+2T>C mutation identified in Fam3727, showing monoallelic deletion of exon 9. (b) cDNA analysis from Fam0484 (proband 2), who is heterozygous for c.1194+3A>C, demonstrates that exon 9 is deleted on one allele. (c) Schematic structures of normal and mutant forms of CTR9 protein showing tetratricopeptide repeat domains (shaded boxes). The c.1194+2T>C and c.1194+3A>C splice-site mutations result in an in-frame deletion of amino acids 320–398 containing two tetratricopeptide repeats.

Figure 3. Schematic scale diagram of PAF1c and RNA Pol II.

PAF1c consists of six subunits: PAF1, LEO1, CDC73, CTR9, RFT1 and WDR61. CTR9 and CDC73 are cancer predisposition genes, mutations in which cause Wilms tumour and hyperparathyroidism-jaw tumour syndrome, respectively. RNA Pol II, RNA polymerase II.