Sorting of soluble TNF-receptor for granule storage in hematopoietic cells as a principle for targeting of selected proteins to inflamed sites.
Author
Summary, in English
Hematopoietic cells have secretory lysosomes that degranulate at the inflammatory site upon stimulation. We asked whether one could target exogenous proteins with a therapeutic potential to secretory lysosomes in hematopoietic cells. For this purpose, we expressed a soluble tumor necrosis factor (TNF) receptor form (sTNFR1) in hematopoietic cell lines. In order to accomplish targeting to secretory lysosomes, both endoplasmic reticulum (ER) retention and constitutive secretion have to be prevented. ER export was facilitated by addition of a transmembrane (tm) sequence, and constitutive secretion was overcome by incorporating a cytosolic sorting signal (Y) from CD63. This signal directed the resulting sTNFR1-tm-Y to secretory lysosomes. Confirmation of these results was provided by biosynthetic radiolabeling, subcellular fractionation, immunofluorescence microscopy, and immunoelectron microscopy. The tm-Y fragment was cleaved by proteolysis, resulting in generation of the membrane-free sTNFR1 in secretory lysosomes. Our results suggest a potential for using the storage organelles of hematopoietic cells as vehicles for targeting sites of inflammation with therapeutically active agents. (C) 2003 by The American Society of Hematology.
Publishing year
2003
Language
English
Pages
682-688
Publication/Series
Blood
Volume
102
Issue
2
Links
Document type
Journal article
Publisher
American Society of Hematology
Topic
- Hematology
Status
Published
ISBN/ISSN/Other
- ISSN: 1528-0020