Identification and characterization of a membrane receptor that binds to human STC1
Hin Ting Wan1, Alice Hm Ng1, Wang Ka Lee1
1Department of Biology, Croucher Institute for Environmental Sciences, Hong Kong Baptist University, Hong Kong SAR, China.
Abstract:
Stanniocalcin-1 (STC1) is a hypocalcemic hormone originally identified in bony fishes. The mammalian homolog is found to be involved in inflammation and carcinogenesis, among other physiological functions. In this study, we used the TriCEPS-based ligand-receptor methodology to identify the putative binding proteins of human STC1 (hSTC1) in the human leukemia monocytic cell line, ThP-1. LC-MS/MS analysis of peptides from shortlisted hSTC1-binding proteins detected 32 peptides that belong to IGF2/MPRI. Surface plasmon resonance assay demonstrated that hSTC1 binds to immobilized IGF2R/MPRI with high affinity (10-20 nM) and capacity (Rmax 70-100%). The receptor binding data are comparable with those of (CREG) cellular repressor of E1A-stimulated gene a known ligand of IGF2R/MPRI, with Rmax of 75-80% and affinity values of 1-2 nM. The surface plasmon resonance competitive assays showed CREG competed with hSTC1 in binding to IGF2R/MPRI. The biological effects of hSTC1 on ThP-1 cells were demonstrated via IGF2R/MPRI to significantly reduce secreted levels of IL-1β. This is the first study to reveal the high-affinity binding of hSTC1 to the membrane receptor IGF2R/MPRI.
Insights
Stanniocalcin-1 (STC1) binds with high affinity to the IGF2 receptor (IGF2R/MPRI). This interaction in leukemia cells reduces inflammatory cytokine IL-1β, revealing a novel STC1-IGF2R/MPRI signaling pathway.
Area of Science:
- Endocrinology
- Molecular Biology
- Cell Biology
Background:
- Stanniocalcin-1 (STC1) is a hormone involved in calcium regulation, with mammalian homologs implicated in inflammation and cancer.
- The specific membrane receptors and signaling pathways of human STC1 (hSTC1) remain largely uncharacterized.
Purpose of the Study:
- To identify binding proteins of human STC1 (hSTC1) using a ligand-receptor methodology.
- To characterize the binding kinetics and biological function of the hSTC1-receptor interaction in leukemia cells.
Main Methods:
- TriCEPS-based ligand-receptor capture assay to identify hSTC1 binding partners.
- Liquid chromatography-tandem mass spectrometry (LC-MS/MS) for protein identification.
- Surface plasmon resonance (SPR) assays to quantify binding affinity and kinetics.
- SPR competitive assays to assess ligand competition.
- Measurement of IL-1β levels in ThP-1 cells.
Main Results:
- IGF2 receptor (IGF2R/MPRI) was identified as a high-affinity binding protein for hSTC1.
- SPR assays confirmed high-affinity binding of hSTC1 to IGF2R/MPRI (10-20 nM), comparable to CREG.
- Competitive SPR assays demonstrated that CREG and hSTC1 compete for IGF2R/MPRI binding.
- hSTC1 binding to IGF2R/MPRI significantly reduced secreted IL-1β levels in ThP-1 cells.
Conclusions:
- This study identifies IGF2R/MPRI as a high-affinity membrane receptor for human Stanniocalcin-1 (hSTC1).
- The hSTC1-IGF2R/MPRI interaction modulates inflammatory responses by reducing IL-1β secretion in leukemia cells.
- This discovery elucidates a novel signaling axis for STC1 with potential implications in cancer and inflammation research.
More Related Videos
Related Concept Videos
01:15G Protein-coupled Receptors
GPCRs are also called heptahelical, 7TM, or serpentine receptors, and consist of seven (H1-H7) transmembrane alpha-helices that span the bilayer to form a cylindrical core. The transmembrane helices are connected by three extracellular loops and three...
01:28Types of Receptors: Cell Surface Receptors