Melanoma antigen-D2: A nucleolar protein undergoing delocalization during cell cycle and after cellular stress

Biochim Biophys Acta. 2016 Apr;1863(4):581-95. doi: 10.1016/j.bbamcr.2015.12.010. Epub 2015 Dec 17.

Abstract

Melanoma antigen D2 (MAGE-D2) is recognized as a cancer diagnostic marker; however, it has poorly characterized functions. Here, we established its intracellular localization and shuttling during cell cycle progression and in response to cellular stress. In normal conditions, MAGE-D2 is present in the cytoplasm, nucleoplasm, and nucleoli. Within the latter, MAGE-D2 is mostly found in the granular and the dense fibrillar components, and it interacts with nucleolin. Transfection of MAGE-D2 deletion mutants demonstrated that Δ203-254 leads to confinement of MAGE-D2 to the cytoplasm, while Δ248-254 prevents its accumulation in nucleoli but still allows its presence in the nucleoplasm. Consequently, this short sequence belongs to a nucleolar localization signal. MAGE-D2 deletion does not alter the nucleolar organization or rRNA levels. However, its intracellular localization varies with the cell cycle in a different kinetic than nucleolin. After genotoxic and nucleolar stresses, MAGE-D2 is excluded from nucleoli and concentrates in the nucleoplasm. We demonstrated that its camptothecin-related delocalization results from two distinct events: a rapid nucleolar release and a slower phospho-ERK-dependent cytoplasm to nucleoplasm translocation, which results from an increased flux from the cytoplasm to nucleoplasm. In conclusion, MAGE-D2 is a dynamic protein whose shuttling properties could suggest a role in cell cycle regulation.

Keywords: Camptothecin; Cell cycle; Cellular stress; MAP kinases; Melanoma antigen protein; Nucleolus.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / metabolism*
  • Antigens, Neoplasm / metabolism*
  • Cell Cycle / physiology*
  • Cell Nucleolus / metabolism
  • Cell Nucleus / metabolism
  • Cytoplasm / metabolism
  • HCT116 Cells
  • HEK293 Cells
  • HT29 Cells
  • Humans
  • MCF-7 Cells
  • Protein Transport
  • Stress, Physiological / physiology*
  • Tumor Cells, Cultured

Substances

  • Adaptor Proteins, Signal Transducing
  • Antigens, Neoplasm
  • MAGED2 protein, human