GDNF synthesis, signaling, and retrograde transport in motor neurons

Abstract Glial cell line–derived neurotrophic factor (GDNF) is a 134 amino acid protein belonging in the GDNF family ligands (GFLs). GDNF was originally isolated from rat glial cell lines and identified as a neurotrophic factor with the ability to promote dopamine uptake within midbrain dopaminergic neurons. Since its discovery, the potential neuroprotective effects of GDNF have been researched extensively, and the effect of GDNF on motor neurons will be discussed herein. Similar to other members of the TGF-β superfamily, GDNF is first synthesized as a precursor protein (pro-GDNF). After a series of protein cleavage and processing, the 211 amino acid pro-GDNF is finally converted into the active and mature form of GDNF. GDNF has the ability to trigger receptor tyrosine kinase RET phosphorylation, whose downstream effects have been found to promote neuronal health and survival. The binding of GDNF to its receptors triggers several intracellular signaling pathways which play roles in promoting the development, survival, and maintenance of neuron-neuron and neuron-target tissue interactions. The synthesis and regulation of GDNF have been shown to be altered in many diseases, aging, exercise, and addiction. The neuroprotective effects of GDNF may be used to develop treatments and therapies to ameliorate neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS). In this review, we provide a detailed discussion of the general roles of GDNF and its production, delivery, secretion, and neuroprotective effects on motor neurons within the mammalian neuromuscular system.

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Early transplantation of an encapsulated glial cell line—derived neurotrophic factor—producing cell demonstrating strong neuroprotective effects in a rat model of Parkinson disease

Journal of Neurosurgery ◽

10.3171/jns.2005.102.1.0080 ◽

2005 ◽

Vol 102 (1) ◽

pp. 80-89 ◽

Cited By ~ 51

Author(s):

Takao Yasuhara ◽

Tetsuro Shingo ◽

Kenichiro Muraoka ◽

Kazuki Kobayashi ◽

Akira Takeuchi ◽

...

Keyword(s):

Parkinson Disease ◽

Cell Line ◽

Glial Cell ◽

Rat Model ◽

Neurotrophic Factor ◽

Dopaminergic Neurons ◽

Neuroprotective Effects ◽

Content Type ◽

Glial Proliferation ◽

Fine Print

Object. Glial cell line—derived neurotrophic factor (GDNF) has been shown to confer neuroprotective effects on dopaminergic neurons. The authors investigated the effects of GDNF on 6-hydroxydopamine (6-OHDA)—treated dopaminergic neurons in vitro and in vivo. Methods. First, the authors examined how 1, 10, or 100 ng/ml of GDNF, administered to cells 24 hours before, simultaneously with, or 2 or 4 hours after 6-OHDA was added, affected dopaminergic neurons. In a primary culture of E14 murine ventral mesencephalic neurons, earlier treatment with the higher dosage of GDNF suppressed 6-OHDA—induced loss of dopaminergic neurons better than later treatment. Next, the authors examined whether continuous infusion of GDNF at earlier time points would demonstrate a greater neuroprotective effect in a rat model of Parkinson disease (PD). They established a human GDNF-secreting cell line, called BHK-GDNF, and encapsulated the cells into hollow fibers. The encapsulated cells were unilaterally implanted into the striatum of adult rats 1 week before; simultaneously with; or 1, 2, or 4 weeks after 6-OHDA was given to induce lesions of the same striatum. With the earlier transplantation of a BHK-GDNF capsule, there was a significant reduction in the number of amphetamine-induced rotations displayed by the animals. Rats that had received earlier implantation of BHK-GDNF capsules displayed more tyrosine hydroxylase—positive neurons in the substantia nigra pars compacta and a tendency for glial proliferation in the striatum. Conclusions. These neuroprotective effects may be related to glial proliferation and signaling via the GDNF receptor α1. The results of this study support a role for this grafting technique in the treatment of PD.

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