Abstract
In the last decade, Nerve Growth Factor (NGF)-based clinical approaches have lacked specific and efficient Tyrosine Kinase A (TrkA) agonists for brain delivery. Nowadays, the characterization of novel small peptidomimetic is taking centre stage in preclinical studies, in order to overcome the main size-related limitation in brain delivery of NGF holoprotein for Central Nervous System (CNS) pathologies. Here we investigated the NGF mimetic properties of the human NGF 1–14 sequence (hNGF1–14) and its derivatives, by resorting to primary cholinergic and dorsal root ganglia (DRG) neurons. Briefly, we observed that: 1) hNGF1–14 peptides engage the NGF pathway through TrkA phosphorylation at tyrosine 490 (Y490), and activation of ShcC/PI3K and Plc-γ/MAPK signalling, promoting AKT-dependent survival and CREB-driven neuronal activity, as seen by levels of the immediate early gene c-Fos, of the cholinergic marker Choline Acetyltransferase (ChAT), and of Brain Derived Neurotrophic Factor (BDNF); 2) their NGF mimetic activity is lost upon selective TrkA inhibition by means of GW441756; 3) hNGF1–14 peptides are able to sustain DRG survival and differentiation in absence of NGF. Furthermore, the acetylated derivative Ac-hNGF1–14 demonstrated an optimal NGF mimetic activity in both neuronal paradigms and an electrophysiological profile similar to NGF in cholinergic neurons. Cumulatively, the findings here reported pinpoint the hNGF1–14 peptide, and in particular its acetylated derivative, as novel, specific and low molecular weight TrkA specific agonists in both CNS and PNS primary neurons.
Highlights
Nerve Growth Factor (NGF) is the prototypic neurotrophin primarily described for its ability to sustain survival and induce differentiation of peripheral neurons [1]
We observed that: 1) hNGF1–14 peptides engage the NGF pathway through TrkA phosphorylation at tyrosine 490 (Y490), and activation of ShcC/PI3K and Plc-γ/MAPK signalling, promoting AKT-dependent survival and CREB-driven neuronal activity, as seen by levels of the immediate early gene c-Fos, of the cholinergic marker Choline Acetyltransferase (ChAT), and of Brain Derived Neurotrophic Factor (BDNF); 2) their NGF mimetic activity is lost upon selective TrkA inhibition by means of GW441756; 3) hNGF1–14 peptides are able to sustain dorsal root ganglia (DRG) survival and differentiation in absence of NGF
We found that hNGF1–14 retains biological activity of the NGF protein, activating the early and late signalling intermediates of the NGF-TrkA pathway, and results in CREB-driven gene transcription and Immediate Early Gene c-Fos nuclear elevation
Summary
Nerve Growth Factor (NGF) is the prototypic neurotrophin primarily described for its ability to sustain survival and induce differentiation of peripheral neurons [1]. TrkA engagement by its ligand induces receptor dimerization and autophosphorylation at the tyrosine residue 490 (Y490), driving the activation of early and downstream signalling molecules, such as 1) phospholipase C-γ (PLC-γ) pathways leading to intracellular calcium release, ion channels and transcription factors expression, 2) neuronal SH2 containing protein (ShcC)-driven phosphatidylinositol 3-kinase (PI3k) activation, which is critical to inhibit c-Jun N-terminal kinase (JNK) induced apoptosis by activating AKT-mediated survival, and 3) mitogen-activated protein kinase (MAPK)/Extracellular Signal-regulated Kinase (ERK) route. The p75 receptor activates pro-survival pathways, such as AKT, to act synergistically with Trk-mediated neurotrophin effects. It can operate in an antagonistic manner to cell survival and growth, triggering several potential pro-apoptotic cascades [1,2]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
