Profibrillin-1 maturation by human dermal fibroblasts: proteolytic processing and molecular chaperones.
Fibrillin-1 is synthesized as a proprotein that undergoes proteolytic processing in the unique C-terminal domain by a member of the PACE/furin family of endoproteases. This family of endoproteases is active in the trans-Golgi network (TGN), but metabolic labeling studies have been controversial as to whether profibrillin-1 is processed intracellularly or after secretion. This report provides evidence that profibrillin-1 processing is not an intracellular event. Bafilomycin A(1) and incubation of dermal fibroblasts at 22 degrees C were used to block secretion in the TGN to confirm that profibrillin-1 processing did not occur in this compartment. Profibrillin-1 immunoprecipitation studies revealed that two endoplasmic reticulum-resident molecular chaperones, BiP and GRP94, interacted with profibrillin-1. To determine the proprotein convertase responsible for processing profibrillin-1, a specific inhibitor of furin, alpha-1-antitrypsin, Portland variant, was both expressed in the cells and added to cells exogenously. In both cases, the inhibitor blocked the processing of profibrillin-1, providing evidence that furin is the enzyme responsible for profibrillin-1 processing. These studies delineate the secretion and proteolytic processing of profibrillin-1, and identify the proteins that interact with profibrillin-1 in the secretory pathway.
Wallis
Debra D
DD
Department of Internal Medicine, University of Texas-Houston Medical School, Houston, Texas 77030, USA.
Putnam
Elizabeth A
EA
Cretoiu
Jill S
JS
Carmical
Sonya G
SG
Cao
Shi-Nian
SN
Thomas
Gary
G
Milewicz
Dianna M
DM
D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D002478:Cells, Cultured; D020405:Dermis / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D000091342:Endoplasmic Reticulum Chaperone BiP; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005089:Exocytosis / Q000187:drug effects / Q000502:physiology; D000071838:Fibrillin-1; D000071837:Fibrillins; D005347:Fibroblasts / Q000378:metabolism*; D045683:Furin / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D006360:Heat-Shock Proteins; D006801:Humans; D018942:Macrolides / Q000494:pharmacology; D008565:Membrane Proteins / Q000378:metabolism; D008840:Microfilament Proteins / Q000378:metabolism*; D018832:Molecular Chaperones / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle; D011498:Protein Precursors / Q000378:metabolism*; D011499:Protein Processing, Post-Translational / Q000502:physiology*; D000515:alpha 1-Antitrypsin; D054392:Adipokines
D002352:Carrier Proteins; D000091342:Endoplasmic Reticulum Chaperone BiP; D004791:Enzyme Inhibitors; D000071838:Fibrillin-1; D000071837:Fibrillins; D045683:Furin; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D018942:Macrolides; D008565:Membrane Proteins; D008840:Microfilament Proteins; D018832:Molecular Chaperones; D011498:Protein Precursors; D000515:alpha 1-Antitrypsin; C000605722:FBN1 protein, human; D054392:Adipokines; C113421:alpha 1-antitrypsin Portland; C018551:glucose-regulated proteins; C040929:bafilomycin A1