Two PTP receptors mediate CSPG inhibition by convergent and divergent signaling pathways in neurons

Sci Rep. 2016 Nov 16;6:37152. doi: 10.1038/srep37152.

Abstract

Receptor protein tyrosine phosphatase σ (PTPσ) and its subfamily member LAR act as transmembrane receptors that mediate growth inhibition of chondroitin sulfate proteoglycans (CSPGs). Inhibition of either receptor increases axon growth into and beyond scar tissues after CNS injury. However, it is unclear why neurons express two similar CSPG receptors, nor whether they use the same or different intracellular pathways. We have now studied the signaling pathways of these two receptors using N2A cells and primary neurons derived from knockout mice. We demonstrate that both receptors share certain signaling pathways (RhoA, Akt and Erk), but also use distinct signals to mediate CSPG actions. Activation of PTPσ by CSPGs selectively inactivated CRMP2, APC, S6 kinase and CREB. By contrast LAR activation inactivated PKCζ, cofilin and LKB1. For the first time, we propose a model of the signaling pathways downstream of these two CSPG receptors. We also demonstrate that deleting both receptors exhibits additive enhancement of axon growth in adult neuronal cultures in vitro. Our findings elucidate the novel downstream pathways of CSPGs and suggest potential synergy of blocking their two PTP receptors.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • Chondroitin Sulfate Proteoglycans / genetics
  • Chondroitin Sulfate Proteoglycans / metabolism*
  • MAP Kinase Signaling System / physiology*
  • Mice
  • Neurons / cytology
  • Neurons / metabolism*
  • Protein Kinases / genetics
  • Protein Kinases / metabolism*
  • Receptor-Like Protein Tyrosine Phosphatases, Class 5 / genetics
  • Receptor-Like Protein Tyrosine Phosphatases, Class 5 / metabolism*

Substances

  • Chondroitin Sulfate Proteoglycans
  • Protein Kinases
  • Receptor-Like Protein Tyrosine Phosphatases, Class 5