Pigment epithelium-derived factor hinders photoreceptor cell death by reducing intracellular calcium in the degenerating retina

Cell Death Dis. 2018 May 1;9(5):560. doi: 10.1038/s41419-018-0613-y.

Abstract

Calcium ions play a critical role in neuronal cell death. Pigment epithelium-derived factor (PEDF) is a promising neuroprotective protein for photoreceptor cells but the mechanisms mediating its effects against retinal degeneration are still not well characterized. We addressed this question in the rd1 degenerating mouse retina that bears a mutation in the Pde6b gene encoding one subunit of the phosphodiesterase enzyme. Loss of phosphodiesterase activity in rod photoreceptor cells increases cyclic guanosine monophosphate (cGMP) levels leading to a rise in intracellular calcium. Short-term treatments with recombinant human PEDF protein decreased intracellular calcium in photoreceptors in vivo. Taking advantage of calcium pump blockers, we defined that PEDF signaling acts on PMCA calcium pumps to lower intracellular calcium. PEDF restrained cell death pathways activated by high calcium levels and engaging calpains, BAX and AIF. The neurotrophic effects were mediated by the PEDF receptor (PEDF-R), encoded by the PNPLA2 gene. Finally, peptides containing the neurotrophic domain of PEDF targeted these same cell death pathways in vivo. The findings reveal rescue from death of degenerating photoreceptor cells by a PEDF-mediated preservation of intracellular calcium homeostasis.

Publication types

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

MeSH terms

  • Animals
  • Calcium / metabolism*
  • Calcium Signaling*
  • Cell Line
  • Cyclic GMP / genetics
  • Cyclic GMP / metabolism
  • Eye Proteins / genetics
  • Eye Proteins / metabolism*
  • Eye Proteins / pharmacology
  • Humans
  • Mice
  • Mice, Transgenic
  • Mutation
  • Nerve Growth Factors / genetics
  • Nerve Growth Factors / metabolism*
  • Nerve Growth Factors / pharmacology
  • Photoreceptor Cells, Vertebrate / metabolism*
  • Photoreceptor Cells, Vertebrate / pathology
  • Retinal Degeneration / genetics
  • Retinal Degeneration / metabolism*
  • Retinal Degeneration / pathology
  • Retinal Pigment Epithelium / metabolism*
  • Retinal Pigment Epithelium / pathology
  • Serpins / genetics
  • Serpins / metabolism*
  • Serpins / pharmacology

Substances

  • Eye Proteins
  • Nerve Growth Factors
  • Serpins
  • pigment epithelium-derived factor
  • Cyclic GMP
  • Calcium