The role of glial cell line-derived neurotrophic factor family member artemin in neurological disorders and cancers.

Artemin (ARTN) is a member of the glial cell line-derived neurotrophic factor (GDNF) family ligands (GFLs), which encompasses family members, GDNF, neurturin (NRTN) and persephin (PSPN). ARTN is also referred to as Enovin or Neublastin, and bears structural characteristics of the TGF-β superfamily. ARTN contains a dibasic cleavage site (RXXR) that is predicted to be cleaved by furin to yield a carboxy-terminal 113 amino acid mature form. ARTN binds preferentially to receptor GFRα3, coupled to a receptor tyrosine kinase RET, forming a signalling complex for the regulation of intracellular pathways that affect diverse outcomes of nervous system development and homoeostasis. Standard signalling cascades activated by GFLs via RET include the phosphorylation of mitogen-activated protein kinase or MAPK (p-ERK, p-p38 and p-JNK), PI3K-AKT and Src. Neural cell adhesion molecule (NCAM) is an alternative signalling receptor for ARTN in the presence of GFRα1, leading to activation of Fyn and FAK. Further, ARTN also interacts with heparan sulphate proteoglycan syndecan-3 and mediates non-RET signalling via activation of Src kinases. This review discusses the role of ARTN in spinal cord injury, neuropathic pain and other neurological disorders. Additionally, ARTN plays a role in non-neuron tissues, such as the formation of Peyer's patch-like structures in the lymphoid tissue of the gut. The emerging role of ARTN in cancers and therapeutic resistance to cancers is also explored. Further research is necessary to determine the function of ARTN in a tissue-specific manner, including its signalling mechanisms, in order to improve the therapeutic potential of ARTN in human diseases.