Cytoplasmic polyadenylation element binding protein is a conserved target of tumor suppressor HRPT2/CDC73

Cell Death Differ. 2010 Oct;17(10):1551-65. doi: 10.1038/cdd.2010.32. Epub 2010 Mar 26.

Abstract

Parafibromin, a tumor suppressor protein encoded by HRPT2/CDC73 and implicated in parathyroid cancer and the hyperparathyroidism-jaw tumor (HPT-JT) familial cancer syndrome, is part of the PAF1 transcriptional regulatory complex. Parafibromin has been implicated in apoptosis and growth arrest, but the mechanism by which its loss of function promotes neoplasia is poorly understood. In this study we report that a hypomorphic allele of hyrax (hyx), the Drosophila homolog of HRPT2/CDC73, rescues the loss-of-ventral-eye phenotype of lobe (Akt1s1). Such rescue is consistent with previous reports that hyx/parafibromin is required for the nuclear transduction of Wingless (Wg)/Wnt signals and that Wg signaling antagonizes lobe function. A screen using double hyx/lobe heterozygotes identified an additional interaction with orb and orb2, the homologs of mammalian cytoplasmic polyadenylation element binding protein (CPEB), a translational regulatory protein. Hyx and orb2 heterozygotes lived longer and were more resistant to starvation than controls. In mammalian cells, knockdown of parafibromin expression reduced levels of CPEB1. Chromatin immunoprecipitation (ChIP) showed occupancy of CPEB1 by endogenous parafibromin. Bioinformatic analysis revealed a significant overlap between human transcripts potentially regulated by parafibromin and CPEB. These results show that parafibromin may exert both transcriptional and, through CPEB, translational control over a subset of target genes and that loss of parafibromin (and CPEB) function may promote tumorigenesis in part by conferring resistance to nutritional stress.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • Animals
  • Carboxy-Lyases / genetics
  • Carboxy-Lyases / metabolism
  • Cell Line
  • Chromatin Immunoprecipitation
  • Drosophila / growth & development
  • Drosophila / metabolism
  • Drosophila Proteins / genetics
  • Drosophila Proteins / metabolism*
  • Humans
  • Larva / metabolism
  • Mutation
  • RNA Interference
  • RNA, Small Interfering
  • Signal Transduction
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Tumor Suppressor Proteins / genetics
  • Tumor Suppressor Proteins / metabolism*
  • Wnt Proteins / metabolism
  • mRNA Cleavage and Polyadenylation Factors / genetics
  • mRNA Cleavage and Polyadenylation Factors / metabolism*

Substances

  • CDC73 protein, human
  • CPEB1 protein, human
  • Drosophila Proteins
  • Hyx protein, Drosophila
  • Orb2 protein, Drosophila
  • RNA, Small Interfering
  • Transcription Factors
  • Tumor Suppressor Proteins
  • Wnt Proteins
  • mRNA Cleavage and Polyadenylation Factors
  • Carboxy-Lyases