Different responses of PC12 cells to different pro-nerve growth factor protein variants

Neurochem Int. 2019 Oct:129:104498. doi: 10.1016/j.neuint.2019.104498. Epub 2019 Jul 3.

Abstract

The present work aimed to explore the innovative hypothesis that different transcript/protein variants of a pro-neurotrophin may generate different biological outcomes in a cellular system. Nerve growth factor (NGF) is important in the development and progression of neurodegenerative and cancer conditions. Mature NGF (mNGF) originates from a precursor, proNGF, produced in mouse in two major variants, proNGF-A and proNGF-B. Different receptors bind mNGF and proNGF, generating neurotrophic or neurotoxic outcomes. It is known that dysregulation in the proNGF/mNGF ratio and in NGF-receptors expression affects brain homeostasis. To date, however, the specific roles of the two major proNGF variants remain unexplored. Here we attempted a first characterization of the possible differential effects of proNGF-A and proNGF-B on viability, differentiation and endogenous ngf gene expression in the PC12 cell line. We also investigated the differential involvement of NGF receptors in the actions of proNGF. We found that native mouse mNGF, proNGF-A and proNGF-B elicited different effects on PC12 cell survival and differentiation. Only mNGF and proNGF-A promoted neurotrophic responses when all NGF receptors are exposed at the cell surface. Tropomyosine receptor kinase A (TrkA) blockade inhibited cell differentiation, regardless of which NGF was added to culture media. Only proNGF-A exerted a pro-survival effect when TrkA was inhibited. Conversely, proNGF-B exerted differentiative effects when the p75 neurotrophin receptor (p75NTR) was antagonized. Stimulation with NGF variants differentially regulated the autocrine production of distinct proNgf mRNA. Overall, our findings suggest that mNGF and proNGF-A may elicit similar neurotrophic effects, not necessarily linked to activation of the same NGF-receptor, while the action of proNGF-B may be determined by the NGF-receptors balance. Thus, the proposed involvement of proNGF/NGF on the development and progression of neurodegenerative and tumor conditions may depend on the NGF-receptors balance, on specific NGF trancript expression and on the proNGF protein variant ratio.

Keywords: Ngf gene expression; PC12 cells; Pro-nerve growth factors; Tropomyosine receptor kinase A; p75 neurotrophin receptor.

Publication types

  • Comparative Study

MeSH terms

  • Animals
  • Cell Differentiation / drug effects
  • Gene Expression Regulation / drug effects
  • Male
  • Mice
  • Nerve Growth Factor / pharmacology*
  • Nerve Growth Factors / biosynthesis
  • Nerve Growth Factors / genetics
  • Nerve Tissue Proteins
  • PC12 Cells / drug effects*
  • Protein Isoforms / pharmacology
  • Protein Precursors / biosynthesis
  • Protein Precursors / genetics
  • Protein Precursors / pharmacology*
  • Proteome
  • RNA, Messenger / biosynthesis
  • RNA, Messenger / genetics
  • Rats
  • Receptor, trkA / antagonists & inhibitors
  • Receptors, Growth Factor
  • Receptors, Nerve Growth Factor / antagonists & inhibitors
  • Species Specificity

Substances

  • Nerve Growth Factors
  • Nerve Tissue Proteins
  • Protein Isoforms
  • Protein Precursors
  • Proteome
  • RNA, Messenger
  • Receptors, Growth Factor
  • Receptors, Nerve Growth Factor
  • pro-nerve growth factor, mouse
  • pro-nerve growth factor, rat
  • Ngfr protein, rat
  • Nerve Growth Factor
  • Receptor, trkA