How does conserved dopamine neurotrophic factor protect against and rescue neurodegeneration of PC12 cells?
NEURAL REGENERATION RESEARCH
Authors: Mei, Jia-ming; Niu, Chao-shi
Abstract
Conserved dopamine neurotrophic factor protects and rescues dopaminergic neurodegeneration induced by 6-hydroxydopamine in vivo, but its potential value in treating Parkinson's disease remains controversial. Here, we used the proteasome inhibitors lactacystin and MG132 to induce neurodegeneration of PC12 cells. Afterwards, conserved dopamine neurotrophic factor was administrated as a therapeutic factor, both pretreatment and posttreatment. Our results showed that (1) conserved dopamine neurotrophic factor enhanced lactacystin/MG132-induced cell viability and morphology, and attenuated alpha-synuclein accumulation in differentiated PC12 cells. (2) Enzyme linked immunosorbent assay showed up-regulated 26S proteasomal activity in MG132-induced PC12 cells after pre- and posttreatment with conserved dopamine neurotrophic factor. Similarly, 26S proteasome activity was upregulated in lactacystin-induced PC 12 cells pretreated with conserved dopamine neurotrophic factor. (3) With regard proteolytic enzymes (specifically, glutamyl peptide hydrolase, chymotrypsin, and trypsin), glutamyl peptide hydrolase activity was up-regulated in lactacystin/MG132-administered PC 12 cells after pre-and posttreatment with conserved dopamine neurotrophic factor. However, upregulation of chymotrypsin activity was only observed in MG 132-administered PC12 cells pretreated with conserved dopamine neurotrophic factor. There was no change in trypsin expression. We conclude that conserved dopamine neurotrophic factor develops its neurotrophic effects by modulating proteasomal activities, and thereby protects and rescues PC 12 cells against neurodegeneration.
Antioxidative CXXC Peptide Motif From Mesencephalic Astrocyte-Derived Neurotrophic Factor Antagonizes Programmed Cell Death
FRONTIERS IN CELL AND DEVELOPMENTAL BIOLOGY
Authors: Bozok, Valentina; Yu, Li-ying; Palgi, Jaan; Arumae, Urmas
Abstract
Mesencephalic astrocyte-derived neurotrophic factor (MANF) is a potent survival-promoting protein with neurorestorative effect for neurodegenerative diseases. Its mechanism of action, albeit poorly known, depends strongly on the CXXC motif (CKGC). Here we studied the survival-promoting properties of the CKGC tetrapeptide from MANE In the Jurkat T lymphocytic cell line, CKGC potently inhibits death receptor Fas-induced apoptosis and mildly counteracts mitochondrial apoptosis and necroptosis. The peptide with serines instead of cysteines (SKGS) has no survival-promoting activity. The cytoprotective efficiency of the peptide against Fas-induced apoptosis is significantly improved by reduction of its cysteines by dithiotreitol, suggesting that it protects the cells via cysteine thiol groups, partially as an antioxidant. CKGC neutralizes the reactive oxygen species, maintains the mitochondrial membrane potential and prevents activation of the effector caspases in the Jurkat cells with activated Fas. The peptide does not require intracellular administration, as it is endocytosed and resides mainly in the Golgi. Finally, the peptide also potently promotes survival of cultured primary dopaminergic neurons.