The neuronal tyrosine kinase receptor ligand ALKAL2 mediates persistent pain
Manon Defaye, … , Gerald W. Zamponi, Christophe Altier
Manon Defaye, … , Gerald W. Zamponi, Christophe Altier
Published May 24, 2022
Citation Information: J Clin Invest. 2022;132(12):e154317. https://doi.org/10.1172/JCI154317.
View: Text | PDF
Research Article Neuroscience Article has an altmetric score of 121

The neuronal tyrosine kinase receptor ligand ALKAL2 mediates persistent pain

Abstract

The anaplastic lymphoma kinase (ALK) is a receptor tyrosine kinase known for its oncogenic potential that is involved in the development of the peripheral and central nervous system. ALK receptor ligands ALKAL1 and ALKAL2 were recently found to promote neuronal differentiation and survival. Here, we show that inflammation or injury enhanced ALKAL2 expression in a subset of TRPV1+ sensory neurons. Notably, ALKAL2 was particularly enriched in both mouse and human peptidergic nociceptors, yet weakly expressed in nonpeptidergic, large-diameter myelinated neurons or in the brain. Using a coculture expression system, we found that nociceptors exposed to ALKAL2 exhibited heightened excitability and neurite outgrowth. Intraplantar CFA or intrathecal infusion of recombinant ALKAL2 led to ALK phosphorylation in the lumbar dorsal horn of the spinal cord. Finally, depletion of ALKAL2 in dorsal root ganglia or blocking ALK with clinically available compounds crizotinib or lorlatinib reversed thermal hyperalgesia and mechanical allodynia induced by inflammation or nerve injury, respectively. Overall, our work uncovers the ALKAL2/ALK signaling axis as a central regulator of nociceptor-induced sensitization. We propose that clinically approved ALK inhibitors used for non–small cell lung cancer and neuroblastomas could be repurposed to treat persistent pain conditions.

Authors

Manon Defaye, Mircea C. Iftinca, Vinicius M. Gadotti, Lilian Basso, Nasser S. Abdullah, Mélissa Cuménal, Francina Agosti, Ahmed Hassan, Robyn Flynn, Jérémy Martin, Vanessa Soubeyre, Gaetan Poulen, Nicolas Lonjon, Florence Vachiery-Lahaye, Luc Bauchet, Pierre Francois Mery, Emmanuel Bourinet, Gerald W. Zamponi, Christophe Altier

×

Figure 2

CFA inflammation induces ALKAL2 upregulation in TRPV1 neurons.

Options: View larger image (or click on image) Download as PowerPoint
CFA inflammation induces ALKAL2 upregulation in TRPV1 neurons. (A) Exper...
(A) Experimental approach used to conduct the microarray analysis from TRPV1 neurons, 72 hours after i.pl. CFA. (B) FACS isolation of TRPV1-pHluorin neurons. Representative FACS plot of GFP+ population in WT (top) and TRPV1-pHluorin (bottom) mice. SSC-A side scatter area; FSCA- forward scatter area. (C) Scatter plot representation of genes regulated in CFA conditions. Genes that passed a threshold of log2 fold change in differential expression analysis are represented as green when downregulated and red when upregulated. All genes are listed in Supplemental Table 1. (D) qRT-PCR assessment of ALKAL2 upregulation in the DRG ipsilateral to the CFA injection (Ipsi) (n = 9), compared with the contralateral side (Contra) (n = 9) and naive control (n = 8). Statistical analysis was performed using Kruskal-Wallis followed by Dunn’s post hoc test. *P < 0.05; ***P < 0.001. (E) Representative Western blot of ALKAL2 in the DRG ipsilateral to the CFA injection compared with the contralateral side. (F) Quantification of ALKAL2 protein level from Western blot experiments. Each dot represents a sample collected from a different animal (n = 6 per group). Statistical analysis was performed by unpaired t test (F). ****P < 0.0001. Data are represented as mean ± SEM.