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Håkan Axelson

Håkan Axelson

Research team manager

Håkan Axelson

Nuclear colocalization of c-myc protein and hsp70 in cells transfected with human wild-type and mutant c-myc genes

Author

  • M Henriksson
  • M Classon
  • H Axelson
  • G Klein
  • J Thyberg

Summary, in English

Using immunofluorescence and electron microscopy we have studied the localization of wild-type and mutant c-myc proteins transiently expressed in CV-1 cells. In agreement with our previous observations, wild-type c-myc protein accumulated in large amorphous globules in the nucleus. All mutant proteins tested accumulated in the nucleus as well, but gave rise to morphologically different inclusion bodies. Many small globules appeared in cells transfected with D145-262 (deletion of amino acids 145-262), while cells transfected with D371-412 or D414-433 generated structures looking like a fine network or like beads on a string. In addition, a particulate cytoplasmic staining appeared in some cells transfected with the wild-type gene and in cells transfected with mutants D145-262 or D414-433. Since the c-myc protein has been reported to stimulate expression of exogenous hsp70 protein, we also examined the intracellular distribution of hsp70 in the transfected cells. Double immunofluorescence microscopy revealed that hsp70 codistributed with the c-myc protein in distinct globules in the nucleus of many but not all myc-positive cells. However, the levels of hsp70 transcripts were not significantly raised compared to nontransfected and vector-transfected cells. Likewise, the levels of hsp70 protein did not vary significantly. These findings indicate that overexpression of c-myc stimulates translocation of preexisting hsp70 from the cytoplasm into the nucleus, rather than influencing hsp70 expression. Conceivably, this may represent one of several mechanisms whereby the cell deals with excessive amounts of c-myc protein.

Department/s

  • Division of Translational Cancer Research

Publishing year

1992-12

Language

English

Pages

94-383

Publication/Series

Experimental Cell Research

Volume

203

Issue

2

Document type

Journal article

Publisher

Academic Press

Keywords

  • Animals
  • Cell Line
  • Cell Nucleus
  • Cytoplasm
  • Genes, myc
  • Heat-Shock Proteins
  • Humans
  • Microscopy, Electron
  • Microscopy, Fluorescence
  • Mutation
  • Proto-Oncogene Proteins c-myc
  • Transfection

Status

Published

ISBN/ISSN/Other

  • ISSN: 0014-4827