alpha-synuclein and Pheochromocytoma

Aberrant α-synuclein aggregation due to the deficiency of ubiquitin-proteasome or of autophagy characterizes the parkinson disease (PD). High mobility group box 1 (HMGB1) is a novel stress sensor to mediate the persistent neuro-inflammation and the consequent progressive neurodegeneration, via controlling the cellular autophagy/apoptosis checkpoint during inflammation. Moreover, HMGB1 has been recently indicated to involve in the autophagic degradation of α-synuclein.. In the current study, we investigated the influence of the overexpressed α-synuclein of wild type (wt) or mutant type (A53T and A30P, mt) on the cytosolic levels of HMGB1 and Beclin1 and on the starvation-induced autophagy in pheochromocytoma PC12 cells. And then we explored the overexpression of HMGB1 or of Beclin1 on the α-synuclein degradation and on the autophagy in the α-synuclein-overexpressed PC12 cells.. It was demonstrated that α-synuclein overexpression inhibited the trans-location of HMGB1 from nucleus to cytosol and reduced the cytosolic level of Beclin1 in PC12 cells, and inhibited the starvation-induced autophagy via downregulating autophagy-associated markers and via reducing the autophagic vesicles in PC12 cells under starvation. On the other side, the intracellular promotion of either HMGB1 or Beclin1 upregulated the α-synuclein degradation and ameliorated the α-synuclein-mediated autophagy reduction in PC12 cells. However, the exogenous HMGB1 treatment exerted no such regulation in PC12 cells.. In summary, our study confirmed the positive regulation by HMGB1 and Beclin1 on the α-synuclein degradation and on the starvation-induced autophagy in PC12 cells, implying both markers as prominent targets to promote the α-synuclein degradation.

Topics: Adrenal Gland Neoplasms; alpha-Synuclein; Animals; Apoptosis Regulatory Proteins; Autophagy; Beclin-1; Gene Expression Regulation, Neoplastic; HMGB1 Protein; PC12 Cells; Pheochromocytoma; Proteolysis; Rats; RNA, Messenger; Signal Transduction; Time Factors; Transfection

Curcumin, a dietary polyphenol, has shown a potential to act on the symptoms of neurodegenerative disorders, including Alzheimer's and Parkinson's diseases, as a consequence of its antioxidant, anti-inflammatory and anti-protein aggregation properties. Unfortunately, curcumin undergoes rapid degradation at physiological pH into ferulic acid, vanillin and dehydrozingerone, making it an unlikely drug candidate. Here, we evaluated the ability of some curcumin by-products: dehydrozingerone (1), its O-methyl derivative (2), zingerone (3), and their biphenyl analogues (4-6) to interact with α-synuclein (AS), using CD and fluorescence spectroscopy. In addition, the antioxidant properties and the cytoprotective effects in rat pheochromocytoma (PC12) cells prior to intoxication with H2O2, MPP+ and MnCl2 were examined while the Congo red assay was used to evaluate the ability of these compounds to prevent aggregation of AS. We found that the biphenyl zingerone analogue (6) interacts with high affinity with AS and also displays the best antioxidant properties while the biphenyl analogues of dehydrozingerone (4) and of O-methyl-dehydrozingerone (5) are able to partially inhibit the aggregation process of AS, suggesting the potential role of a hydroxylated biphenyl scaffold in the design of AS aggregation inhibitors.

Topics: Adrenal Gland Neoplasms; alpha-Synuclein; Alzheimer Disease; Animals; Antioxidants; Cell Line, Tumor; Curcumin; Cytoprotection; Guaiacol; Parkinson Disease; Pheochromocytoma; Rats; Styrenes

Parkinson's disease (PD) is characterized by the progressive degeneration of dopaminergic neurons in the substantia nigra (SN) with the presence of alpha-synuclein inclusions termed Lewy bodies. The aggregation of alpha-synuclein into oligomeric species affects neuronal viability, having a causal role in the development of PD. The neuroprotective effects of protocatechuic acid (PAc) have been reported. However, the effects of PAc on tyrosine hydroxylase (TH) and alpha-synuclein in rat pheochromocytoma (PC12) cells treated with 1-methyl-4-phenylpyridinium ion (MPP(+)) remains unclear. In this study, we demonstrated that PAc inhibited the cytotoxicity, apoptotic morphology, reduction of TH expression and abnormal oligomeration of alpha-synuclein in PC12 cells treated with MPP(+). Taken together, our results indicate that the neuroprotective effects of PAc on PC12 cells treated with MPP(+) is related to the inhibition of the oligomerization of alpha-synuclein.

Topics: alpha-Synuclein; Animals; Dopamine; Hydroxybenzoates; Neurotoxins; PC12 Cells; Pheochromocytoma; Rats; Tyrosine 3-Monooxygenase

Melatonin, a secretory product of the pineal gland, is involved in the regulation of circadian and seasonal rhythms, in oncostasis, and in inducing osteoblast differentiation. Furthermore, melatonin is a scavenger of a number of reactive oxygen and reactive nitrogen species both in vitro and in vivo. In this study, the antioxidant nature of melatonin was shown to prevent cultured neural cells from apoptosis induced by endocrine-disrupting chemical, maneb. The neurotoxicity of the fungicide, maneb (1 microg/mL), on the PC12 cells was elicited through apoptotic cell death, concomitant with aggregation of alpha-synuclein, a feature of Parkinson's disease. Activation of caspase-3/7 was associated with this process. A fluorescence rationing technique using a mitochondrial dye revealed that maneb altered the mitochondrial membrane potential of the neural cells. However, melatonin (1 nm) largely prevented the neural cells from the neural toxicant by inhibition of both caspase-3/7 activation and disruption of the mitochondrial transmembrane potential. Furthermore, aggregation of alpha-synuclein by maneb was also inhibited by melatonin. Thus, melatonin prevents maneb-induced neurodegeneration at a nighttime physiological blood concentration, most likely by inhibiting the aggregation of alpha-synuclein as well as preventing mitochondrial dysfunction in PC 12 cells.

Topics: Adrenal Gland Neoplasms; alpha-Synuclein; Animals; Fungicides, Industrial; Maneb; Melatonin; PC12 Cells; Pheochromocytoma; Rats