Neuronal membrane proteasome-derived peptides modulate NMDAR-dependent neuronal signaling to promote changes in gene expression

Mol Biol Cell. 2024 Jan 1;35(1):ar6. doi: 10.1091/mbc.E23-06-0218. Epub 2023 Nov 1.

Abstract

The neuronal membrane proteasome (NMP) degrades intracellular proteins into peptides that are released directly into the extracellular space, whereby they stimulate neurons to promote signaling mechanisms that remain unknown. Here, we demonstrate that neuronal stimulation promotes NMP activity and, subsequently, enhanced production of NMP peptides. We show that these neuronal activity-dependent NMP peptides can rapidly promote N-methyl-D-aspartate receptor (NMDAR)-dependent calcium influx in neurons. This leads to sustained phosphorylation of the well-defined stimulus-induced transcription factor, cyclic AMP response element (CRE)-binding protein (CREB). Downstream of these events, we identified changes to neuronal target genes which included increased expression of immediate early genes (e.g., Fos, Npas4, Egr4) and other genes known to have critical neuroregulatory roles. Further observations led to the discovery that NMP peptide-induced changes in gene expression is dependent on NMDARs and independent of AMPA receptors or voltage-gated sodium channels. These data demonstrate that NMP peptides are endogenous and selective activators of NMDA receptors and act as sufficient and novel stimuli within the context of neuronal activity-dependent signaling. This novel pathway is parallel to classic neuronal activity-dependent programs and points to NMP and its resulting peptides as potential modulators of neuronal function.

MeSH terms

  • Calcium / metabolism
  • Cyclic AMP Response Element-Binding Protein / genetics
  • Cyclic AMP Response Element-Binding Protein / metabolism
  • Gene Expression
  • Neurons / metabolism
  • Peptides / metabolism
  • Proteasome Endopeptidase Complex* / metabolism
  • Receptors, N-Methyl-D-Aspartate* / genetics
  • Receptors, N-Methyl-D-Aspartate* / metabolism

Substances

  • Receptors, N-Methyl-D-Aspartate
  • Proteasome Endopeptidase Complex
  • Peptides
  • Cyclic AMP Response Element-Binding Protein
  • Calcium