Quartz Crystal Microbalance Measurement of Histidine-Rich Glycoprotein and Stanniocalcin-2 Binding to Each Other and to Inflammatory Cells

Abstract

The plasma protein histidine-rich glycoprotein (HRG) is implicated in the polarization of macrophages to an M1 antitumoral phenotype. The broadly expressed secreted protein stanniocalcin 2 (STC2), also implicated in tumor inflammation, is an HRG interaction partner. With the aim to biochemically characterize the HRG and STC2 complex, binding of recombinant HRG and STC2 preparations to each other and to cells was explored using the quartz crystal microbalance (QCM) methodology. The functionality of recombinant proteins was tested in a phagocytosis assay, where HRG increased phagocytosis by monocytic U937 cells while STC2 suppressed HRG-induced phagocytosis. The binding of HRG to STC2, measured using QCM, showed an affinity between the proteins in the nanomolar range, and both HRG and STC2 bound individually and in combination to vitamin D3-treated, differentiated U937 monocytes. HRG, but not STC2, also bound to formaldehyde-fixed U937 cells irrespective of their differentiation stage in part through the interaction with heparan sulfate. These data show that HRG and STC2 bind to each other as well as to U937 monocytes with high affinity, supporting the relevance of these interactions in monocyte/macrophage polarity.

The Association between Histidine-Rich Glycoprotein rs10770 Genotype and Recurrent Miscarriage in Iranian Women

“…This protein also has four intradomain disulfide bonds, two interdomain disulfide bonds, and six N-glycosylated regions [ 11 ]. HRG is a protein that acts as an adapter and can bind to various ligands including heparin [ 12 ], tropomyosin [ 13 ], plasminogen [ 9 ], Zn2+ [ 14 ], thrombospondin (TSP) [ 15 ], heme [ 16 ], fibrinogen [ 17 ], complement components [ 18 ], phospholipids [ 19 ], vasculostatin [ 20 ], and immunoglobulin G [ 21 ]. Also, HRG is involved in the regulation of many biological processes, including blood coagulation, angiogenesis, fibrinolysis, and the immune system [ 10 ].…”

Assessing Impedance Analyzer Data Quality by Fractional Order Calculus: A QCM Sensor Case Study

“…The use of the quartz crystal microbalance (QCM) sensor in liquid media [29][30][31] has brought great benefits in expanding the range of applications [32][33][34], especially in biological media [35]. A significant experimental effort was required to monitor the QCM sensor's series resonance frequency and damping parameters using an active method (oscillator) [36][37][38] or passive interrogation, such as as ring-down methods [39][40][41] in high-viscosity liquid media.…”