Identification of sequence determinants of human nuclear dUTPase isoform localization

Beverly A Tinkelenberg, William Fazzone, Frank J Lynch, Robert D Ladner

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

dUTP nucleotidohydrolase (dUTPase) catalyzes the hydrolysis of dUTP to dUMP and pyrophosphate and is the central regulator of cellular dUTP pools. Nuclear (DUT-N) and mitochondrial (DUT-M) isoforms of the protein have been identified in humans and arise from the same gene by the alternative use of 5' exons. Recently, it has been shown that these isoforms are aberrantly expressed in some cancers and overexpression of dUTPase in the nucleus is associated with resistance to chemotherapeutic agents that target thymidylate biosynthesis. In this study, we have examined the signals necessary for dUTPase isoform localization using green fluorescent protein fusion constructs. We report that the N-terminal 23 amino acids of DUT-N are required but not sufficient for complete nuclear localization. Within this region, we identified a small cluster of basic residues (K(14)R(15)R(17)) that resemble a classic monopartite nuclear localization signal (NLS). Mutation of these residues completely abolishes nuclear localization. In addition, phosphorylation of Ser11 near the putative NLS has no affect on DUT-N nuclear localization. Through deletion analysis we show improved sorting of DUT-N to the nucleus when most of the protein sequence is present. Therefore, we conclude that DUT-N may contain a complex NLS that is located throughout the entire protein.

Original languageEnglish
Pages (from-to)39-46
Number of pages8
JournalExperimental Cell Research
Volume287
Issue number1
Publication statusPublished - 01 Jul 2003

Keywords

  • 3T3 Cells
  • Alternative Splicing
  • Amino Acid Sequence
  • Animals
  • Cell Compartmentation
  • Cell Nucleus
  • Drug Resistance, Neoplasm
  • Eukaryotic Cells
  • Gene Expression Regulation, Neoplastic
  • HT29 Cells
  • Humans
  • Mice
  • Mutation
  • Neoplasms
  • Protein Isoforms
  • Pyrophosphatases
  • Recombinant Fusion Proteins
  • Serine
  • Signal Transduction
  • Thymidylate Synthase
  • Uridine Triphosphate
  • Journal Article
  • Research Support, U.S. Gov't, P.H.S.

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