title: Binding of tissue-type plasminogen activator to the glucose-regulated protein 78 (GRP78) modulates plasminogen activation and promotes human neuroblastoma cell proliferation in vitro.
abstract: The glucose-regulated protein 78 (GRP78) is a plasminogen (Pg) receptor on the cell surface. In this study, we demonstrate that GRP78 also binds the tissue-type plasminogen activator (t-PA), which results in a decrease in K(m) and an increase in the V(max) for both its amidolytic activity and activation of its substrate, Pg. This results in accelerated Pg activation when GRP78, t-PA, and Pg are bound together. The increase in t-PA activity is the result of a mechanism involving a t-PA lysine-dependent binding site in the GRP78 amino acid sequence (98)LIGRTWNDPSVQQDIKFL(115). We found that GRP78 is expressed on the surface of neuroblastoma SK-N-SH cells where it is co-localized with the voltage-dependent anion channel (VDAC), which is also a t-PA-binding protein in these cells. We demonstrate that both Pg and t-PA serve as a bridge between GRP78 and VDAC bringing them together to facilitate Pg activation. t-PA induces SK-N-SH cell proliferation via binding to GRP78 on the cell surface. Furthermore, Pg binding to the COOH-terminal region of GRP78 stimulates cell proliferation via its microplasminogen domain. This study confirms previous findings from our laboratory showing that GRP78 acts as a growth factor-like receptor and that its association with t-PA, Pg, and VDAC on the cell surface may be part of a system controlling cell growth.
authors: From the Department of Biological Sciences, Laboratory of Environmental Neurotoxicology Faculty of Medicine, Universidad Católica del Norte, Coquimbo 1781421, Chile and the Department of Pathology, Duke University, Medical Center, Durham, North Carolina 27710 gonza002@mc.duke.edu.
authors: Mario
authors: M
authors: Gonzalez-Gronow
authors: From the Department of Biological Sciences, Laboratory of Environmental Neurotoxicology Faculty of Medicine, Universidad Católica del Norte, Coquimbo 1781421, Chile and.
authors: Cristian Farias
authors: CF
authors: Gomez
authors: the Department of Pathology, Duke University, Medical Center, Durham, North Carolina 27710.
authors: Gustaaf G
authors: GG
authors: de Ridder
authors: the Department of Pathology, Duke University, Medical Center, Durham, North Carolina 27710.
authors: Rupa
authors: R
authors: Ray
authors: the Department of Pathology, Duke University, Medical Center, Durham, North Carolina 27710.
authors: Salvatore V
authors: SV
authors: Pizzo
mesh_terms: D000581:Amidohydrolases / Q000378:metabolism; D000595:Amino Acid Sequence; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D049109:Cell Proliferation; D000091342:Endoplasmic Reticulum Chaperone BiP; D004789:Enzyme Activation; D006360:Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D007700:Kinetics; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009447:Neuroblastoma / Q000378:metabolism / Q000473:pathology; D010958:Plasminogen / Q000378:metabolism*; D011485:Protein Binding; D013379:Substrate Specificity; D010959:Tissue Plasminogen Activator / Q000378:metabolism*; D050994:Voltage-Dependent Anion Channels / Q000378:metabolism
chemical_list: D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; D006360:Heat-Shock Proteins; D050994:Voltage-Dependent Anion Channels; D010958:Plasminogen; D010959:Tissue Plasminogen Activator; D000581:Amidohydrolases
keywords: Brain; Brain Physiology; Cell Proliferation; GRP78; Kinetics; Neurochemistry; Pg Activation; Protein Folding; t-PA