Th17 cells and interleukin‐17 (IL‐17) have been found to play an important role in the pathology of multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE). Response to IL‐17, reactive astrocytes accompany with immune cells infiltration and axonal damage in MS/EAE. However, the role and the regulatory mechanism of IL‐17‐activated astrocytes in inflammation and in the EAE process still remain largely unknown. Here, we elucidated that miR‐409‐3p and miR‐1896, as co‐upregulated microRNAs in activated astrocytes and in EAE mice, targeted suppressor of cytokine signaling proteins 3 (SOCS3). Overexpression of miR‐409‐3p or miR‐1896 significantly reduced SOCS3 expression and increased phosphorylation of STAT3 as well as induced the inflammatory cytokines production (IL‐1β, IL‐6, IP‐10, MCP‐1, and KC), CD4+T cells migration and demyelination, in turn aggravating EAE development. Importantly, the effects of co‐overexpression of miR‐409‐3p and miR‐1896 in vitro or in vivo are strongly co‐operative. In contrast, simultaneously silenced miR‐409‐3p and miR‐1896 co‐operatively ameliorates inflammation and demyelination in the central nervous system of EAE mice. Collectively, our findings highlight that miR‐409‐3p and miR‐1896 co‐ordinately promote the production of inflammatory cytokines in reactive astrocytes through the SOCS3/STAT3 pathway and enhance reactive astrocyte‐directed chemotaxis of CD4+T cells, leading to aggravate pathogenesis in EAE mice. Co‐inhibition of miR‐409‐3p and miR‐1896 may be a therapeutic target for treating MS and neuroinflammation.

Glial cell line-derived neurotrophic factor (GDNF) is a potent neurotrophic factor for the substantia nigra (SN) dopamine (DA) neurons. The transmembrane signaling of GDNF is mediated by a unique receptor system, including the ligand binding receptor GDNF family receptor alpha (GFRalpha) and the transmembrane signaling receptor Ret or neural cell adhesion molecule-140 (NCAM-140). Here, we found that another transmembrane cell adhesion molecule, integrin, a heterodimer consisting of alpha and beta subunits, also mediates the transmembrane signaling of GDNF. The results showed that the level of phosphorylated Src homology 2 domain containing (Shc), which was associated with the cytoplasmic domain of integrin beta1, increased after GDNF administration. Coimmunoprecipitation analysis demonstrated that integrin beta1 could form a complex with GFRalphal. The simulation of molecular modeling showed that four H-bonds were formed between integrin beta1 and GFRalpha. These data indicate that integrin beta1 is involved in the transmembrane signaling of GDNF and suggest that integrin beta1 may be an alternative signaling receptor for GDNF.

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As the most prevalent primary brain tumor, gliomas are highly metastatic, invasive and are characteristic of high levels of glial cell-line derived neurotrophic factor (GDNF). GDNF is an important factor for invasive glioma cell growth; however, the underlying mechanism involved is unclear. In this study, we affirm a significantly higher expression of the precursor of N-cadherin (proN-cadherin) in most gliomas compared with normal brain tissues. Our findings reveal that GDNF interacts with the extracellular domain of proN-cadherin, which suggests that proN-cadherin mediates GDNF-induced glioma cell migration and invasion. We hypothesize that proN-cadherin might cause homotypic adhesion loss within neighboring cells and at the same time promote heterotypic adhesion within the extracellular matrix (ECM) through a certain mechanism. This study also demonstrates that the interaction between GDNF and proN-cadherin activates specific intracellular signaling pathways; furthermore, GDNF promoted the secretion of matrix metalloproteinase-9 (MMP-9), which degrades the ECM via proN-cadherin. To reach the future goal of developing novel therapies of glioma, this study, reveals a unique mechanism of glioma cell migration and invasion.

Glial cell line-derived neurotrophic factor (GDNF) is a potent survival factor, and a member of the transforming growth factor β (TGF-β) superfamily acting on different neuronal activities. GDNF was originally identified as a neurotrophic factor crucially involved in the survival of dopaminergic neurons of the nigrostriatal pathway and is currently an established therapeutic target in Parkinson's disease. However, GDNF was later reported to be highly expressed in gliomas, especially in glioblastomas, and was demonstrated as a potent proliferation factor involved in the development and migration of gliomas. Here, we review our current understanding and progress made so far by researchers in our laboratories with references to relevant articles to support our discoveries. We present past and recent discoveries on the mechanisms involved in the protection of neurons by GDNF and examine its emerging roles in gliomas, as well as reasons for the abnormal expression in Glioblastoma Multiforme (GBM). Collectively, our work establishes a paradigm by which the ability of GDNF to protect dopaminergic neurons from degradation and its corresponding effects on glioma cells points to an underlying biological vulnerability in the effects of GDNF in the normal brain which can be subverted for use by cancer cells. Hence, presenting novel opportunities for intervention in glioma therapies.