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Sorting for storage in myeloid cells of nonmyeloid proteins and chimeras with the propeptide of myeloperoxidase precursor.

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Author

Summary, in English

During formation of polymorphonuclear neutrophils, proteins are synthesized for storage in granules. Whereas sorting of proteins into distinct subtypes of cytoplasmic granules may reflect the coordinated expression of the proteins contained in them, still the mechanism(s) for the retrieval of proteins from the constitutive secretion is unknown. To investigate the mechanisms of retrieval, nonmyeloid secretory proteins were expressed in myeloid cell lines, and their subcellular fate was assessed. The contribution of the propeptide (MPOpro) of the myeloperoxidase (MPO) precursor was investigated by determining the fate of chimeras containing MPOpro. The nonmyeloid protein alpha(1)-microglobulin (alpha(1)-m) was targeted to storage organelles in 32D cells and colocalized with the lysosomal marker LAMP-1, whereas soluble TNF receptor 1 (sTNFR1) was secreted without granule targeting. Fusion of MPOpro to alpha(1)-m delayed exit from endoplasmic reticulum (ER), but subsequent targeting to dense organelles was indistinguishable from that of alpha(1)-m alone. Fusion proteins between MPOpro and sTNFR1 or green fluorescent protein expressed in myeloid 32D, K562, or PLB-985 cells did not associate stably with calreticulin or calnexin, molecular chaperones that normally interact transiently with the MPO precursor, but were still efficiently retained in the ER followed by degradation. We conclude that normally secreted, nonmyeloid proteins can be targeted efficiently to storage organelles in myeloid cells, that myeloid cells selectively target some proteins for storage but not others, and that MPOpro may contribute to the prolonged ER retention of the MPO precursor independent of the ER-molecular chaperones calreticulin and calnexin.

Publishing year

2002

Language

English

Pages

279-288

Publication/Series

Journal of Leukocyte Biology

Volume

71

Issue

2

Document type

Journal article

Publisher

John Wiley & Sons Inc.

Topic

  • Cell and Molecular Biology

Keywords

  • Non-P.H.S.
  • U.S. Gov't
  • fSupport
  • Non-U.S. Gov't
  • Support
  • Tumor Necrosis Factor/metabolism
  • Receptors
  • Protein Transport
  • Protein Precursors/genetics/*metabolism
  • Peroxidase/genetics/*metabolism
  • Myeloid Cells/*metabolism
  • Membrane Glycoproteins/genetics/*metabolism
  • Immunohistochemistry
  • K562 Cells
  • Transfection
  • P.H.S.
  • Human
  • Chimeric Proteins/genetics/*metabolism
  • Cell Line
  • Cell Differentiation/genetics
  • CD/metabolism
  • Antigens

Status

Published

ISBN/ISSN/Other

  • ISSN: 1938-3673