Secreted Isoform of Human Lynx1 (SLURP-2): Spatial Structure and Pharmacology of Interactions with Different Types of Acetylcholine Receptors

Sci Rep. 2016 Aug 3;6:30698. doi: 10.1038/srep30698.

Abstract

Human-secreted Ly-6/uPAR-related protein-2 (SLURP-2) regulates the growth and differentiation of epithelial cells. Previously, the auto/paracrine activity of SLURP-2 was considered to be mediated via its interaction with the α3β2 subtype of the nicotinic acetylcholine receptors (nAChRs). Here, we describe the structure and pharmacology of a recombinant analogue of SLURP-2. Nuclear magnetic resonance spectroscopy revealed a 'three-finger' fold of SLURP-2 with a conserved β-structural core and three protruding loops. Affinity purification using cortical extracts revealed that SLURP-2 could interact with the α3, α4, α5, α7, β2, and β4 nAChR subunits, revealing its broader pharmacological profile. SLURP-2 inhibits acetylcholine-evoked currents at α4β2 and α3β2-nAChRs (IC50 ~0.17 and >3 μM, respectively) expressed in Xenopus oocytes. In contrast, at α7-nAChRs, SLURP-2 significantly enhances acetylcholine-evoked currents at concentrations <1 μM but induces inhibition at higher concentrations. SLURP-2 allosterically interacts with human M1 and M3 muscarinic acetylcholine receptors (mAChRs) that are overexpressed in CHO cells. SLURP-2 was found to promote the proliferation of human oral keratinocytes via interactions with α3β2-nAChRs, while it inhibited cell growth via α7-nAChRs. SLURP-2/mAChRs interactions are also probably involved in the control of keratinocyte growth. Computer modeling revealed possible SLURP-2 binding to the 'classical' orthosteric agonist/antagonist binding sites at α7 and α3β2-nAChRs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing
  • Adult
  • Animals
  • Binding Sites / physiology
  • CHO Cells
  • Cell Line
  • Cell Proliferation / physiology
  • Computer Simulation
  • Cricetulus
  • Epilepsy, Temporal Lobe / pathology
  • Evoked Potentials / physiology*
  • Female
  • GPI-Linked Proteins / metabolism*
  • Humans
  • Keratinocytes / metabolism*
  • Middle Aged
  • Nuclear Magnetic Resonance, Biomolecular
  • Oocytes / metabolism
  • PC12 Cells
  • Protein Binding / physiology
  • Rats
  • Receptors, Muscarinic / metabolism*
  • Receptors, Nicotinic / metabolism*
  • Xenopus
  • alpha7 Nicotinic Acetylcholine Receptor / metabolism*

Substances

  • Adaptor Proteins, Signal Transducing
  • GPI-Linked Proteins
  • LYNX1 protein, human
  • Receptors, Muscarinic
  • Receptors, Nicotinic
  • alpha7 Nicotinic Acetylcholine Receptor
  • nicotinic receptor alpha3beta2