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: Mario Gonzalez-Gronow, Cristian Farias Gomez, Gustaaf G de Ridder, Rupa Ray, Salvatore V Pizzo
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 289 Issue 36 Pg. 25166-76 (Sep 05 2014) ISSN: 1083-351X [Electronic] United States
• PMID: 25059665 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Chemical References

• Endoplasmic Reticulum Chaperone BiP
• HSPA5 protein, human
• Heat-Shock Proteins
• Voltage-Dependent Anion Channels
• Plasminogen
• Tissue Plasminogen Activator
• Amidohydrolases

Topics

• Amidohydrolases (metabolism)
• Amino Acid Sequence
• Cell Line, Tumor
• Cell Membrane (metabolism)
• Cell Proliferation
• Endoplasmic Reticulum Chaperone BiP
• Enzyme Activation
• Heat-Shock Proteins (metabolism)
• Humans
• Immunoblotting
• Kinetics
• Microscopy, Fluorescence
• Molecular Sequence Data
• Neuroblastoma (metabolism, pathology)
• Plasminogen (metabolism)
• Protein Binding
• Substrate Specificity
• Tissue Plasminogen Activator (metabolism)
• Voltage-Dependent Anion Channels (metabolism)