How does conserved dopamine neurotrophic factor protect against and rescue neurodegeneration of PC12 cells?

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 PC12 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 PC12 cells after pre- and posttreatment with conserved dopamine neurotrophic factor. However, upregulation of chymotrypsin activity was only observed in MG132-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 PC12 cells against neurodegeneration.

Effects of CDNF on 6-OHDA-induced apoptosis in PC12 cells via modulation of Bcl-2/Bax and caspase-3 activation.

Progressive dopamine neuron degeneration in the substantia nigra pars compacta is considered the most prominent pathological characteristic of Parkinson's disease (PD). Currently, there is no cure, but only the capability to relieve the symptoms of PD. The conserved dopamine neurotrophic factor (CDNF) protects and rescues dopamine neurons in vivo. However, the molecular function of CDNF in PD remains unclear. In present study, we investigated the role and intrinsic mechanism of CDNF in preventing and reversing rat pheochromocytoma (PC12) cells from apoptosis induced by 6-hydroxydopamine (6-OHDA). We demonstrate that 6-OHDA induces cell death in PC12 cells, but that CDNF attenuates this effect in a dose-dependent manner. Further study shows that upregulation of the Bcl-2/Bax ratio and downregulation of caspase-3 activity are observed in a dose-dependent manner upon pre-treatment or post-treatment with CDNF, suggesting a pathway of regulation of apoptosis by CDNF. These data demonstrate that CDNF prevents the apoptosis of PC12 cells induced by 6-OHDA by modulating Bcl-2/Bax and caspase-3 activation.

The analysis of differential induction of hsp70 in the related cerebral domains and nerve fibers of rats after proteasome inhibiton.

BACKGROUND: Parkinson's disease (PD) is popularly called "proteins conformation disease". Heat shock proteins (Hsps) are essential molecular chaperones that handle abnormal protein conformations. The hsp70 family, in particular, represents the most highly conserved molecular chaperones. They constitute a central part of a Ubiquitous-chaperone system. PURPOSE: In the present study, we tested if the induction of hsp70 after proteasome inhibition follows a differential pattern in the related cerebral domains and nerve fibers of rats. METHODS: We used RT-PCR, stereotactic delivery method and immunohistochemical analysis as the molecular tools of investigation. RESULTS: With regard to cerebral domains, the induction of hsp70 exhibited regionality and time-dependence. The intensity of hsp70 expression varied as follows: hippocampus > substantia nigra > frontal lobe > olfactory tract, especially following the order: CA3 > CA2 > CA1 in hippocampus. As for the nerve fibers, it was interesting to find that hsp70 induction was prominent in corpus striatum of lactacystin-treated rats, however hsp70 induction was not observed in the corpus callosum. CONCLUSION: Our study shows the differential induction of hsp70 in Dopamine (DA) nerve fibers and cerebral-association fibers, indicating that hsp70 could protect extrapyramidal system (corpus striatum), not pyramidal system (corpus callosum).

Effect of all-trans retinoic acid on the proliferation and differentiation of brain tumor stem cells.

OBJECTIVE: To investigate the effect of all-trans retinoic acid(ATRA) on the proliferation and differentiation of brain tumor stem cells(BTSCs) in vitro. METHODS: Limiting dilution and clonogenic assay were used to isolate and screen BTSCs from the fresh specimen of human brain glioblastoma. The obtained BTSCs, which were cultured in serum-free medium, were classified into four groups in accordance with the composition of the different treatments. The proliferation of the BTSCs was evaluated by MTT assay. The BTSCs were induced to differentiate in serum-containing medium, and classified into the ATRA group and control group. On the 10th day of induction, the expressions of CD133 and glial fibrillary acidic protein (GFAP) in the differentiated BTSCs were detected by immunofluorescence. The differentiated BTSCs were cultured in serum-free medium, the percentage and the time required for formation of brain tumor spheres (BTS) were observed. RESULTS: BTSCs obtained by limiting dilution were all identified as CD133-positive by immunofluorescence. In serum-free medium, the proliferation of BTSCs in the ATRA group was observed significantly faster than that in the control group, but slower than that in the growth factor group and ATRA/growth factor group, and the size of the BTS in the ATRA group was smaller than that in the latter two groups(P < 0.01). In serum-containing medium, the expression percentages of CD133 and GFAP in the differentiated BTSCs were (2.29% +/- 0.27%) and (75.60% +/- 4.03%) respectively in the ATRA group, and (7.05% +/- 0.49%) and (12.51% +/- 0.77%) respectively in the control group. The differentiation rate of BTSCs in the ATRA group was significantly higher than that in the control group (P < 0.05), but there was still CD133 expressed in the ATRA group. The differentiated BTSCs could re-form BTSs in serum-free medium. The percentage of BTS formation in the ATRA group was(4.84% +/- 0.32%), significantly lower than that in the control group (17.71% +/- 0.78%) (P < 0.05), and the time required for BTS formation in the ATRA group was (10.07 +/- 1.03)d, significantly longer than that in the control group (4.08 +/- 0.35)d (P < 0.05). CONCLUSION: ATRA can promote the proliferation and induce the differentiation of BTSCs, but the differentiation is incomplete, terminal differentiation cannot be achieved and BTSs can be formed again.