PreImplantation Factor bolsters neuroprotection via modulating Protein Kinase A and Protein Kinase C signaling

Cell Death Differ. 2015 Dec;22(12):2078-86. doi: 10.1038/cdd.2015.55. Epub 2015 May 15.

Abstract

A synthetic peptide (sPIF) analogous to the mammalian embryo-derived PreImplantation Factor (PIF) enables neuroprotection in rodent models of experimental autoimmune encephalomyelitis and perinatal brain injury. The protective effects have been attributed, in part, to sPIF's ability to inhibit the biogenesis of microRNA let-7, which is released from injured cells during central nervous system (CNS) damage and induces neuronal death. Here, we uncover another novel mechanism of sPIF-mediated neuroprotection. Using a clinically relevant rat newborn brain injury model, we demonstrate that sPIF, when subcutaneously administrated, is able to reduce cell death, reverse neuronal loss and restore proper cortical architecture. We show, both in vivo and in vitro, that sPIF activates cyclic AMP dependent protein kinase (PKA) and calcium-dependent protein kinase (PKC) signaling, leading to increased phosphorylation of major neuroprotective substrates GAP-43, BAD and CREB. Phosphorylated CREB in turn facilitates expression of Gap43, Bdnf and Bcl2 known to have important roles in regulating neuronal growth, survival and remodeling. As is the case in sPIF-mediated let-7 repression, we provide evidence that sPIF-mediated PKA/PKC activation is dependent on TLR4 expression. Thus, we propose that sPIF imparts neuroprotection via multiple mechanisms at multiple levels downstream of TLR4. Given the recent FDA fast-track approval of sPIF for clinical trials, its potential clinical application for treating other CNS diseases can be envisioned.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Brain Injuries / metabolism
  • Brain Injuries / pathology
  • Cell Line, Tumor
  • Cell Survival / drug effects
  • Cyclic AMP / metabolism
  • Cyclic AMP Response Element-Binding Protein / genetics
  • Cyclic AMP Response Element-Binding Protein / metabolism
  • Cyclic AMP-Dependent Protein Kinases / metabolism*
  • Disease Models, Animal
  • GAP-43 Protein / genetics
  • GAP-43 Protein / metabolism
  • Mice
  • MicroRNAs / genetics
  • MicroRNAs / metabolism
  • Neuroprotective Agents / chemical synthesis
  • Neuroprotective Agents / pharmacology*
  • Peptides / chemical synthesis
  • Peptides / pharmacology*
  • Protein Kinase C / metabolism*
  • Proto-Oncogene Proteins c-bcl-2 / genetics
  • Proto-Oncogene Proteins c-bcl-2 / metabolism
  • RNA Interference
  • Rats
  • Signal Transduction / drug effects*
  • Toll-Like Receptor 4 / antagonists & inhibitors
  • Toll-Like Receptor 4 / genetics
  • Toll-Like Receptor 4 / metabolism
  • bcl-Associated Death Protein / genetics
  • bcl-Associated Death Protein / metabolism

Substances

  • Cyclic AMP Response Element-Binding Protein
  • GAP-43 Protein
  • MIRNLET7 microRNA, rat
  • MicroRNAs
  • Neuroprotective Agents
  • Peptides
  • Proto-Oncogene Proteins c-bcl-2
  • Tlr4 protein, rat
  • Toll-Like Receptor 4
  • bcl-Associated Death Protein
  • preimplantation factor, synthetic
  • Cyclic AMP
  • Cyclic AMP-Dependent Protein Kinases
  • Protein Kinase C