Cathepsin-B fusion proteins misroute secretory protein partners such as the proprotein convertase PC2-7B2 complex toward the lysosomal degradation pathways.
A general strategy is presented for the dominant negative reduction in the levels of heterodimeric soluble proteins within the secretory pathway through fusion of one of its partners C-terminal to the lysosomal enzyme cathepsin B (CB). Stable transfectants of CB-7B2 chimeras in AT20 cells result in a drastic reduction of the endogenous levels of its partner, the proprotein convertase PC2. This dominant negative suppressive effect requires active CB. It was partially reversed by NH(4)Cl, the cell-permeable CB inhibitor CA-074Me, but not by the proteasome inhibitor Lactacystin, suggesting the potential participation of the lysosomal/endosomal degradative pathway in this process.
Rovère
C
C
Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, University of Montreal, 110 Pine Avenue West, Montreal, Quebec, H2W 1R7, Canada.
Mort
J S
JS
Chrétien
M
M
Seidah
N G
NG
D000643:Ammonium Chloride / Q000494:pharmacology; D000818:Animals; D002401:Cathepsin B / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002478:Cells, Cultured; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004151:Dipeptides / Q000494:pharmacology; D008247:Lysosomes / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D051379:Mice; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D051859:Neuroendocrine Secretory Protein 7B2; D010907:Pituitary Hormones / Q000235:genetics / Q000378:metabolism*; D045706:Proprotein Convertase 2; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013381:Subtilisins / Q000235:genetics / Q000378:metabolism*
D015853:Cysteine Proteinase Inhibitors; D004151:Dipeptides; D009419:Nerve Tissue Proteins; D051859:Neuroendocrine Secretory Protein 7B2; D010907:Pituitary Hormones; D011993:Recombinant Fusion Proteins; D000643:Ammonium Chloride; C068250:N-(3-propylcarbamoyloxirane-2-carbonyl)-isoleucyl-proline; D013381:Subtilisins; D045706:Proprotein Convertase 2; D002401:Cathepsin B