Identification and characterization of a membrane receptor for proteolysis-inducing factor on skeletal muscle

Cancer Res. 2007 Dec 1;67(23):11419-27. doi: 10.1158/0008-5472.CAN-07-2602.

Abstract

Proteolysis-inducing factor (PIF) is a sulfated glycoprotein produced by cachexia-inducing tumors, which induces atrophy of skeletal muscle. PIF has been shown to bind specifically with high affinity (K(d), in nanomolar) to sarcolemma membranes from skeletal muscle of both the mouse and the pig, as well as murine myoblasts and a human muscle cell line. Ligand binding was abolished after enzymatic deglycosylation, suggesting that binding was mediated through the oligosaccharide chains in PIF. Chondroitin sulfate, but not heparan or dermatan sulfate, showed competitive inhibition (K(d), 1.1 x 10(-7) mol/L) of binding of PIF to the receptor, suggesting an interaction with the sulfated oligosaccharide chains. Ligand blotting of [(35)S]PIF to triton solublized membranes from C(2)C(12) cells provided evidence for a binding protein of apparent M(r) of approximately 40,000. Amino acid sequence analysis showed the PIF receptor to be a DING protein. Antisera reactive to a 19mer from the N-terminal amino acid residues of the binding protein attenuated protein degradation and activation of the ubiquitin-proteasome pathway induced by PIF in murine myotubes. In addition, the antisera was highly effective in attenuating the decrease in body weight in mice bearing the MAC16 tumor, with a significant increase in muscle wet weight due to an increase in the rate of protein synthesis, together with a reduction in protein degradation through attenuation of the increased proteasome expression and activity. These results confirm that the PIF binding protein has a functional role in muscle protein atrophy in cachexia and that it represents a potential new therapeutic target.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Monoclonal / immunology
  • Binding, Competitive
  • Blotting, Western
  • Cells, Cultured / drug effects
  • Chondroitin Sulfates / pharmacology
  • DNA-Binding Proteins / metabolism
  • Dermatan Sulfate / pharmacology
  • Heparitin Sulfate / pharmacology
  • Mice
  • Mice, Inbred Strains
  • Muscle, Skeletal / drug effects
  • Muscle, Skeletal / metabolism*
  • Myoblasts, Skeletal / drug effects
  • Myoblasts, Skeletal / metabolism
  • Polycomb Repressive Complex 1
  • Proteasome Endopeptidase Complex / metabolism
  • Proteoglycans / metabolism*
  • Receptors, Neurotransmitter / metabolism*
  • Repressor Proteins
  • Sarcolemma / metabolism
  • Ubiquitin-Protein Ligases
  • Ubiquitins / metabolism*

Substances

  • Antibodies, Monoclonal
  • DNA-Binding Proteins
  • Proteoglycans
  • Receptors, Neurotransmitter
  • Repressor Proteins
  • Ubiquitins
  • prolactin-inhibitory factor receptor
  • proteolysis-inducing peptide
  • Dermatan Sulfate
  • Chondroitin Sulfates
  • Heparitin Sulfate
  • Polycomb Repressive Complex 1
  • Rnf2 protein, mouse
  • Ubiquitin-Protein Ligases
  • Proteasome Endopeptidase Complex