cyclin-d1 and Parkinson-Disease

The study aimed to investigate the protective effect of curcumin against oxidative stress-induced injury of Parkinson's disease (PD) through the Wnt/β-catenin signaling pathway in rats.. The successfully established PD rat models and normal healthy rats were randomly assigned into the 6-hydroxydopamine (6-OHDA), the curcumin (Cur) and the control groups. Immunohistochemistry was used to detect the positive expression of tyrosine hydroxylase (TH), dopamine transporter (DAT) and glial fibrillary acidic protein (GFAP). Deutocerebrum primary cells were extracted and classified into the control, 6-OHDA, Cur (5, 10, 15 µmol/L), Dickkopf-1 (DKK-1) and Cur + DKK-1 groups. MTT assays, adhesion tests and TUNEL staining were used to assess cell viability, adhesion and apoptosis, respectively. Western blotting and qRT-PCR were used to examine the protein and mRNA expressions of Wnt3a and β-catenin and the c-myc and cyclinD1 mRNA expressions.. TH and DAT expressions in the Cur group were elevated and GFAP was reduced compared with the 6-OHDA group. Curcumin enhanced viability, survival and adhesion and attenuated apoptosis of deutocerebrum primary cells by activating the Wnt/β-catenin signaling pathway. Higher Wnt3a and β-catenin mRNA and protein expressions and c-myc and cyclinD1 mRNA expressions, enhanced superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) contents, decreased malondialdehyde (MDA) content and elevated mitochondrial membrane potential (∆ψm) were found in the 10 and 15 µmol/L Cur groups compared with the 6-OHDA group. However, opposite tendencies were found in the Cur + DKK-1 group compared to the 10 µmol/L Cur group.. This study suggests that curcumin could protect against oxidative stress-induced injury in PD rats via the Wnt/β-catenin signaling pathway.

Topics: Animals; Apoptosis; Astrocytes; Behavior, Animal; beta Catenin; Cell Adhesion; Cells, Cultured; Curcumin; Cyclin D1; Disease Models, Animal; Dopamine Plasma Membrane Transport Proteins; Glial Fibrillary Acidic Protein; Glutathione Peroxidase; Immunohistochemistry; Intercellular Signaling Peptides and Proteins; Male; Malondialdehyde; Membrane Potential, Mitochondrial; Oxidative Stress; Oxidopamine; Parkinson Disease; Protective Agents; Proto-Oncogene Proteins c-myc; Rats; Rats, Sprague-Dawley; Superoxide Dismutase; Tyrosine 3-Monooxygenase; Wnt Signaling Pathway; Wnt3 Protein

PINK1 (phosphatase and tensin homolog deleted on chromosome 10 (PTEN)-induced kinase 1), a Parkinson's disease-associated gene, was identified originally because of its induction by the tumor-suppressor PTEN. PINK1 promotes cell survival and potentially metastatic functions and protects against cell stressors including chemotherapeutic agents. However, the mechanisms underlying PINK1 function in cancer cell biology are unclear. Here, using several model systems, we show that PINK1 deletion significantly reduced cancer-associated phenotypes including cell proliferation, colony formation and invasiveness, which were restored by human PINK1 overexpression. Results show that PINK1 deletion causes major defects in cell cycle progression in immortalized mouse embryonic fibroblasts (MEFs) from PINK1(-/-) mice, and in BE(2)-M17 cells stably transduced with short hairpin RNA against PINK1. Detailed cell cycle analyses of MEF cell lines from several PINK1(-/-) mice demonstrate an increased proportion of cells in G2/M and decreased number of cells in G1 following release from nocodazole block. This was concomitant with increased double and multi-nucleated cells, a reduced ability to undergo cytokinesis and to re-enter G1, and significant alterations in cell cycle markers, including failure to increase cyclin D1, all indicative of mitotic arrest. PINK1(-/-) cells also demonstrated ineffective cell cycle exit following serum deprivation. Cell cycle defects associated with PINK1 deficiency occur at points critical for cell division, growth and stress resistance in cancer cells were rescued by ectopic expression of human PINK1 and demonstrated PINK1 kinase dependence. The importance of PINK1 for cell cycle control is further supported by results showing that cell cycle deficits induced by PINK1 deletion were linked mechanistically to aberrant mitochondrial fission and its regulation by dynamin-related protein-1 (Drp1), known to be critical for progression of mitosis. Our data indicate that PINK1 has tumor-promoting properties and demonstrates a new function for PINK1 as a regulator of the cell cycle.

Topics: Animals; Cell Division; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cyclin D1; Cytokinesis; Dynamins; Gene Expression Regulation, Neoplastic; GTP Phosphohydrolases; HeLa Cells; Humans; M Phase Cell Cycle Checkpoints; MCF-7 Cells; Mice; Mice, Knockout; Microtubule-Associated Proteins; Mitochondria; Mitochondrial Proteins; Neoplasm Invasiveness; Parkinson Disease; Protein Kinases; RNA Interference; RNA, Small Interfering

Oxidative stress has been shown to mediate neuron damage in Parkinson's disease (PD). In the present report, we intend to clarify the intracellular pathways mediating dopaminergic neuron death after oxidative stress production using post-mitotic PC12 cells treated with the neurotoxin 6-hydroxydopamine (6-OHDA). The use of post-mitotic cells is crucial, because one of the suggested intracellular pathways implicated in neuron death relates to the re-entry of neurons (post-mitotic cells) in the cell cycle. We find that 6-OHDA sequentially increases intracellular oxidants, functional cell damage and caspase-3 activation, leading to cell death after 12 h of incubation. Prevention of cell damage by different antioxidants supports the implication of oxidative stress in the observed neurotoxicity. Oxidative stress-dependent phosphorylation of the MAPK JNK and oxidative stress-independent PKB/Akt dephosphorylation are involved in 6-OHDA neurotoxicity. Decrease in p21(WAF1/CIP1) and cyclin-D1 expression, disappearance of the non-phosphorylated band of retinoblastoma protein (pRb), and expression of proliferating cell nuclear antigen, not present in PC12 post-mitotic cells, suggest a re-entry of differentiated cells into cell cycle. Our results indicate that such a re-entry is mediated by oxidative stress and is involved in 6-OHDA-induced cell death. We conclude that at least three intracellular pathways are involved in 6-OHDA-induced cell death in differentiated PC12 cells: JNK activation, cell cycle progression (both oxidative stress-dependent), and Akt dephosphorylation (not related to the increase of oxidants); the three pathways are necessary for the cells to die, since blocking one of them is sufficient to keep the cells alive.

Topics: Animals; Caspases; Cell Cycle; Cell Death; Cell Differentiation; Cyclin D1; Cyclin-Dependent Kinase Inhibitor p21; Dopamine; Genes, cdc; MAP Kinase Signaling System; Mitosis; Nerve Degeneration; Neurons; Neurotoxins; Oxidative Stress; Oxidopamine; Parkinson Disease; PC12 Cells; Proto-Oncogene Proteins c-akt; Rats; Retinoblastoma Protein; Signal Transduction; Substantia Nigra; Sympatholytics

The causes of sporadic Parkinson's disease (PD) are poorly understood. 6-Hydroxydopamine (6-OHDA), a PD mimetic, is widely used to model this neurodegenerative disorder in vitro and in vivo; however, the underlying mechanisms remain incompletely elucidated. We demonstrate here that 6-OHDA evoked endoplasmic reticulum (ER) stress, which was characterized by an up-regulation in the expression of GRP78 and GADD153 (Chop), cleavage of procaspase-12, and phosphorylation of eukaryotic initiation factor-2 alpha in a human dopaminergic neuronal cell line (SH-SY5Y) and cultured rat cerebellar granule neurons (CGNs). Glycogen synthase kinase-3 beta (GSK3beta) responds to ER stress, and its activity is regulated by phosphorylation. 6-OHDA significantly inhibited phosphorylation of GSK3beta at Ser9, whereas it induced hyperphosphorylation of Tyr216 with little effect on GSK3beta expression in SH-SY5Y cells and PC12 cells (a rat dopamine cell line), as well as CGNs. Furthermore, 6-OHDA decreased the expression of cyclin D1, a substrate of GSK3beta, and dephosphorylated Akt, the upstream signaling component of GSK3beta. Protein phosphatase 2A (PP2A), an ER stress-responsive phosphatase, was involved in 6-OHDA-induced GSK3beta dephosphorylation (Ser9). Blocking GSK3beta activity by selective inhibitors (lithium, TDZD-8, and L803-mts) prevented 6-OHDA-induced cleavage of caspase-3 and poly(ADP-ribose) polymerase (PARP), DNA fragmentations and cell death. With a tetracycline (Tet)-controlled TrkB inducible system, we demonstrated that activation of TrkB in SH-SY5Y cells alleviated 6-OHDA-induced GSK3beta dephosphorylation (Ser9) and ameliorated 6-OHDA neurotoxicity. TrkB activation also protected CGNs against 6-OHDA-induced damage. Although antioxidants also offered neuroprotection, they had little effect on 6-OHDA-induced GSK3beta activation. These results suggest that GSK3beta is a critical intermediate in pro-apoptotic signaling cascades that are associated with neurodegenerative diseases, thus providing a potential target site amenable to pharmacological intervention.

Topics: Animals; Apoptosis; Brain-Derived Neurotrophic Factor; CCAAT-Enhancer-Binding Proteins; Cells, Cultured; Cerebellar Cortex; Cyclin D1; Endoplasmic Reticulum Chaperone BiP; Enzyme Inhibitors; Eukaryotic Initiation Factor-2; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Heat-Shock Proteins; Humans; Lithium Chloride; Molecular Chaperones; Nerve Degeneration; Nerve Tissue Proteins; Neurons; Oxidopamine; Parkinson Disease; PC12 Cells; Phosphoprotein Phosphatases; Phosphorylation; Protein Phosphatase 2; Protein Processing, Post-Translational; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-akt; Rats; Receptor, trkB; Signal Transduction; Thiadiazoles; Transcription Factor CHOP; Transcription Factors