epidermal-growth-factor and Parkinsonian-Disorders

The autophagy-lysosomal pathway plays an important role in the clearance of long-lived proteins and dysfunctional organelles. Lysosomal dysfunction has been implicated in several neurodegenerative disorders including Parkinson's disease and related synucleinopathies that are characterized by accumulations of α-synuclein in Lewy bodies. Recent identification of mutations in genes linked to lysosomal function and neurodegeneration has offered a unique opportunity to directly examine the role of lysosomes in disease pathogenesis. Mutations in lysosomal membrane protein ATP13A2 (PARK9) cause familial Kufor-Rakeb syndrome characterized by early-onset parkinsonism, pyramidal degeneration and dementia. While previous data suggested a role of ATP13A2 in α-synuclein misfolding and toxicity, the mechanistic link has not been established. Here we report that loss of ATP13A2 in human fibroblasts from patients with Kufor-Rakeb syndrome or in mouse primary neurons leads to impaired lysosomal degradation capacity. This lysosomal dysfunction results in accumulation of α-synuclein and toxicity in primary cortical neurons. Importantly, silencing of endogenous α-synuclein attenuated the toxicity in ATP13A2-depleted neurons, suggesting that loss of ATP13A2 mediates neurotoxicity at least in part via the accumulation of α-synuclein. Our findings implicate lysosomal dysfunction in the pathogenesis of Kufor-Rakeb syndrome and suggest that upregulation of lysosomal function and downregulation of α-synuclein represent important therapeutic strategies for this disorder.

Topics: alpha-Synuclein; Animals; Cells, Cultured; Cerebral Cortex; Dementia; Embryo, Mammalian; Epidermal Growth Factor; ErbB Receptors; Fibroblasts; Gene Expression Regulation; Green Fluorescent Proteins; Humans; L-Lactate Dehydrogenase; Leucine; Lysosomal-Associated Membrane Protein 1; Lysosomes; Male; Mice; Mice, Inbred C57BL; Microtubule-Associated Proteins; Mutation; Neurofilament Proteins; Neurons; Parkinsonian Disorders; Proton-Translocating ATPases; RNA, Small Interfering; Statistics, Nonparametric; Time Factors; Transfection; Tritium

We investigated the survival and the possible differentiation fate of the progenitors and immature neurons in the pars compacta of the substantia nigra (SNc) by intranigral injection of a glial cell line-derived neurotropic factor (GDNF) or glial cell line-derived neurotropic factor plus epidermal growth factor (EGF + GDNF) in 6-hydroxydopamine (6-OHDA)-lesioned rats. First, we performed behavioral tests by postural asymmetry and forelimb akinesia on the rats injected with 6-OHDA in striatumat day 7, and selected the qualified model according to the results. Then, intranigral GDNF or EGF + GDNF treatment was administered in the qualified PD model rats. On day 21, behavioral tests were performed with these rats; and then the rats were sacrificed for analyses of β-tubulin isotype-III (Tuj1), nestin, glial fibrillary acidic protein (GFAP), and tyrosine hydroxylase (TH) by immunohistochemistry and Western blotting. The results indicated that GDNF could promote the survival of the progenitor cells and immature neurons in rat SNc following 6-OHDA lesion. Moreover, EGF is capable of enhancing the survival effect of GDNF on the progenitor cells and immature neurons in SNc. On day 21, rapid functional recovery from the lesion-induced behavioral asymmetries was observed in the GDNF or EGF + GDNF treated rats, and the numbers of TH-positive neurons increased in SNc, suggesting that the rats might generate new dopaminergic neurons. Thus, our study provides the new insight that the progenitors and immature neurons in SNc of 6-OHDA-lesioned rats might be able to differentiate toward the dopaminergic neurons fate subsequent to treatment with GDNF or EGF + GDNF.

Topics: Animals; Behavior, Animal; Cell Differentiation; Epidermal Growth Factor; Glial Cell Line-Derived Neurotrophic Factor; Glial Fibrillary Acidic Protein; Male; Neural Stem Cells; Neurons; Oxidopamine; Parkinsonian Disorders; Rats; Rats, Sprague-Dawley; Stem Cells; Substantia Nigra; Tubulin

This study investigated the proliferation and differentiation of adult neural progenitor cells (aNPCs) derived from the striatum and substantia nigra (SN) of parkinsonian rats. We found that aNPCs isolated from the two areas of parkinsonian rats readily formed nestin-enriched neurospheres in vitro and exhibited an ability to differentiate into either neurons or astrocytes. Injection of epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF) into the striatum of parkinsonian rats prior to the harvesting striatal aNPCs significantly increased the neurosphere formation rate and multiple differentiation capacity of these aNPCs when cultured in vitro. These data suggest that striatal and nigral adult NPCs in parkinsonian rats retain the abilities of proliferation and differentiation in vitro. In addition, exogenously applied growth factors could up-regulate the developmental potential of aNPCs. We conclude that our data supports the notion that endogenous cell replacement therapies may be useful for the future treatment of Parkinson's disease (PD).

Topics: Animals; Cell Differentiation; Cell Division; Cells, Cultured; Corpus Striatum; Epidermal Growth Factor; Female; Fibroblast Growth Factors; Immunohistochemistry; Injections, Intraventricular; Neurons; Parkinsonian Disorders; Rats; Rats, Sprague-Dawley; Stem Cells

Topics: Animals; Cell Differentiation; Disease Models, Animal; Dopamine; Ependyma; Epidermal Growth Factor; Female; Fibroblast Growth Factor 2; Growth Substances; Infusion Pumps, Implantable; Injections, Intraventricular; Lateral Ventricles; Neostriatum; Nerve Regeneration; Neurons; Oxidopamine; Parkinsonian Disorders; Rats; Rats, Sprague-Dawley; Recovery of Function; Stem Cells; Tyrosine 3-Monooxygenase