Artemin and an Artemin-Derived Peptide, Artefin, Induce Neuronal Survival, and Differentiation Through Ret and NCAM

Abstract

Artemin (ARTN) is a neurotrophic factor from the GDNF family ligands (GFLs) that is involved in development of the nervous system and neuronal differentiation and survival. ARTN signals through a complex receptor system consisting of the RET receptor tyrosine kinase and a glycosylphosphatidylinositol-anchored co-receptor GFL receptor α, GFRα3. We found that ARTN binds directly to neural cell adhesion molecule (NCAM) and that ARTN-induced neuritogenesis requires NCAM expression and activation of NCAM-associated signaling partners, thus corroborating that NCAM is an alternative receptor for ARTN. We designed a small peptide, artefin, that could interact with GFRα3 and demonstrated that this peptide agonist induces RET phosphorylation and mimics the biological functions of ARTN – neuroprotection and neurite outgrowth. Moreover, artefin mimicked the binding of ARTN to NCAM and required NCAM expression and activation for its neurite elongation effect, thereby suggesting that artefin represents a binding site for NCAM within ARTN. We showed that biological effects of ARTN and artefin can be inhibited by abrogation of both NCAM and RET, suggesting a more complex signaling mechanism that previously thought. As NCAM plays a significant role in neurodevelopment, regeneration, and synaptic plasticity we suggest that ARTN and its mimetics are promising candidates for treatment of neurological disorders and warrant further investigations.

Glial cell line-derived neurotrophic factors (GFLs) and small molecules targeting RET receptor for the treatment of pain and Parkinson’s disease

“…They have conserved patterns of seven cysteine residues and function as homodimers (Eigenbrot and Gerber 1997). They all mainly transmit signals via transmembrane rearranged during transfection (RET) through binding to one of its preferential cognate co-receptors, GDNF family receptor alpha (GFRα), but can also act via neural cell adhesion molecule (NCAM) (Paratcha et al 2003;Ilieva et al 2019) and syndecan-3 (Bespalov et al 2011).…”

Small Molecules and Peptides Targeting Glial Cell Line-Derived Neurotrophic Factor Receptors for the Treatment of Neurodegeneration

“…A tetrameric peptide from the heel region of ARTN activating both NCAM and RET-dependent signaling and a peptide from the heel region of GDNF activating NCAM-dependent signaling, called artefin and gliafin, respectively, have been designed and tested in neuronal cells [74,92]. Artefin promiscuously binds to GFRα1-GFRα3 with high affinity, supports the survival of cerebellar granule neurons upon KCl challenge and stimulates neurite outgrowth from these cells [92]. Gliafin induces neurite outgrowth from hippocampal neurons that express NCAM but not RET [74].…”

“…Peptides are generally better-tolerated and are often more specific, therefore producing less adverse and off-target effects in the organism. We described here two peptides targeting GFL receptors and one produced from GDNF's proregion [74,92,94]. Peptides targeting GFL receptors gliafin and artefin [74,92] are rather bulky, being only slightly smaller compared to GDNF itself.…”

“…We described here two peptides targeting GFL receptors and one produced from GDNF's proregion [74,92,94]. Peptides targeting GFL receptors gliafin and artefin [74,92] are rather bulky, being only slightly smaller compared to GDNF itself. It is unclear if they cross the blood-brain barrier and spread in the tissues, as they have yet to be tested in vivo.…”

“…It is unclear if they cross the blood-brain barrier and spread in the tissues, as they have yet to be tested in vivo. At least artefin seems to target both RET and NCAM, the later molecule with widespread expression in the nervous system [92]. The side effect profile and tissue distribution of these peptides are yet to be evaluated.…”