RESUMEN
OBJECTIVE: There is a lack of effective and long-term safe drugs for the treatment of osteoarthritis (OA). Tetrandrine (Tet) has been approved and used to treat rheumatoid arthritis for several decades, but its effect on OA has not been investigated. Herein, we explored the effect of Tet on OA and its underlying mechanism. METHODS: OA was induced using destabilization of the medial meniscus (DMM) in C57BL/6J mice. The animals were randomly divided into sham, DMM, Tet, celecoxib (CXB), and indomethacin (INDO) groups. Each group was given solvent or corresponding drugs by gavage for 7 weeks after convalescence. Pathological staining, OARSI scores, micro-computed tomography and behavior tests were performed to evaluate the effects of Tet. RESULTS: Tet remarkably alleviated cartilage injury in the knee joint, limited bone remodeling in the subchondral bone, and delayed progression of OA. Tet also significantly relieved joint pain and maintained function. Further mechanistic studies revealed that Tet lowered inflammatory cytokine levels and selectively suppressed gene and protein expression of cyclooxygenase (COX)-2 but not COX-1 (P<0.01). Tet also reduced the production of prostaglandin E2 without damaging the gastric mucosa. CONCLUSION: We found that Tet could selectively inhibit COX-2 gene expression and decrease cytokine levels in mice, thus reducing inflammation and improving OA without obvious gastric adverse events. These results provide a scientific basis for the clinical application of Tet in the treatment of OA.
Asunto(s)
Osteoartritis , Ratones , Animales , Ciclooxigenasa 2/genética , Microtomografía por Rayos X , Ratones Endogámicos C57BL , Osteoartritis/tratamiento farmacológico , Inflamación/tratamiento farmacológicoRESUMEN
BACKGROUND: Golden 2-Like (G2-like) transcription factors play an important role in plant development. However, the roles of these G2-like regulatory genes in response to abiotic stresses in tomato are not well understood. RESULTS: In this study, we identified 66 putative G2-like genes in tomato (Solanum lycopersicum) and classified them into 5 groups (I to V) according to gene structure, motif composition and phylogenetic analysis. The G2-like genes were unevenly distributed across all 12 chromosomes. There were nine pairs of duplicated gene segments and four tandem duplicated SlGlk genes. Analysis of the cis-regulatory elements (CREs) showed that the promoter regions of SlGlks contain many kinds of stress- and hormone-related CREs. Based on RNA-seq, SlGlks were expressed in response to three abiotic stresses. Thirty-six differentially expressed SlGlks were identified; these genes have multiple functions according to Gene Ontology (GO) analysis and are enriched mainly in the zeatin biosynthesis pathway. Further studies exhibited that silencing SlGlk16 in tomato would reduce drought stress tolerance by earlier wilted, lower superoxide dismutase (SOD), peroxidase (POD) activities, less Pro contents and more MDA contents. CONCLUSIONS: Overall, the results of this study provide comprehensive information on G2-like transcription factors and G2-like genes that may be expressed in response to abiotic stresses.
Asunto(s)
Proteínas de Plantas/genética , Solanum lycopersicum/genética , Estrés Fisiológico/genética , Factores de Transcripción/genética , Mapeo Cromosómico , Sequías , Duplicación de Gen , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Estudio de Asociación del Genoma Completo , Solanum lycopersicum/efectos de los fármacos , Solanum lycopersicum/metabolismo , Malondialdehído/metabolismo , Filogenia , Reguladores del Crecimiento de las Plantas/farmacología , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Prolina/metabolismo , Secuencias Reguladoras de Ácidos Nucleicos , Superóxido Dismutasa/genética , Superóxido Dismutasa/metabolismo , Factores de Transcripción/químicaRESUMEN
Intracellular accumulation of the hyperphosphorylated tau is a pathological hallmark in the brain of Alzheimer disease. Activation of extrasynaptic NMDA receptors (E-NMDARs) induces excitatory toxicity that is involved in Alzheimer's neurodegeneration. However, the intrinsic link between E-NMDARs and the tau-induced neuronal damage remains elusive. In the present study, we showed in cultured primary cortical neurons that activation of E-NMDA receptors but not synaptic NMDA receptors dramatically increased tau mRNA and protein levels, with a simultaneous neuronal degeneration and decreased neuronal survival. Memantine, a selective antagonist of E-NMDARs, reversed E-NMDARs-induced tau overexpression. Activation of E-NMDARs in wild-type mouse brains resulted in neuron loss in hippocampus, whereas tau deletion in neuronal cultures and in the mouse brains rescued the E-NMDARs-induced neuronal death and degeneration. The E-NMDARs-induced tau overexpression was correlated with a reduced ERK phosphorylation, whereas the increased MEK activity, decreased binding and activity of ERK phosphatase to ERK, and increased ERK phosphorylation were observed in tau knockout mice. On the contrary, addition of tau proteins promoted ERK dephosphorylation in vitro. Taking together, these results indicate that tau overexpression mediates the excitatory toxicity induced by E-NMDAR activation through inhibiting ERK phosphorylation.
Asunto(s)
Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Sistema de Señalización de MAP Quinasas , Neuronas/patología , Receptores de N-Metil-D-Aspartato/metabolismo , Sinapsis/metabolismo , Proteínas tau/metabolismo , Animales , Muerte Celular , Supervivencia Celular , Células Cultivadas , Activación Enzimática , Eliminación de Gen , Hipocampo/patología , Masculino , Ratones Endogámicos C57BL , Ratones Noqueados , Quinasas de Proteína Quinasa Activadas por Mitógenos/metabolismo , Degeneración Nerviosa/metabolismo , Degeneración Nerviosa/patología , Neuronas/metabolismo , Fosforilación , ARN Mensajero/genética , ARN Mensajero/metabolismo , Ratas Sprague-Dawley , Proteínas tau/genéticaRESUMEN
Abnormal hyperphosphorylation of microtubule-associated protein tau is involved in the pathogenesis of several neurodegenerative disorders including Alzheimer's disease (AD). Helicobacter pylori (H. pylori) infection has been reported to be related with a high risk of AD, but the direct laboratory evidence is lacking. Here we explored the effect of H. pylori infection on tau phosphorylation. The results showed that H. pylori filtrate induced significant tau hyperphosphorylation at several AD-related tau phosphorylation sites, such as Thr205, Thr231, and Ser404, both in mouse neuroblastoma N2a cells and rat brains with activation of glycogen synthase kinase-3ß (GSK-3ß). Application of GSK-3 inhibitors efficiently attenuated the H. pylori-induced tau hyperphosphorylation. Our data provide evidence supporting the role of H. pylori infection in AD-like tau pathology, suggesting that H. pylori eradication may be beneficial in the prevention of tauopathy.
Asunto(s)
Glucógeno Sintasa Quinasa 3/metabolismo , Helicobacter pylori , Hipocampo/metabolismo , Proteínas tau/metabolismo , Animales , Línea Celular Tumoral , Supervivencia Celular/fisiología , Citocinas/metabolismo , Escherichia coli , Glucógeno Sintasa Quinasa 3/antagonistas & inhibidores , Glucógeno Sintasa Quinasa 3 beta , Masculino , Ratones , Microglía/fisiología , Fosforilación/fisiología , Inhibidores de Proteínas Quinasas/farmacología , Ratas , Ratas Sprague-DawleyRESUMEN
Zinc ions highly concentrate in hippocampus and play a key role in modulating spatial learning and memory. At a time when dietary fortification and supplementation of zinc have increased the zinc consuming level especially in the youth, the toxicity of zinc overdose on brain function was underestimated. In the present study, weaning ICR mice were given water supplemented with 15 ppm Zn (low dose), 60 ppm Zn (high dose) or normal lab water for 3 months, the behavior and brain zinc homeostasis were tested. Mice fed high dose of zinc showed hippocampus-dependent memory impairment. Unexpectedly, zinc deficiency, but not zinc overload was observed in hippocampus, especially in the mossy fiber-CA3 pyramid synapse. The expression levels of learning and memory related receptors and synaptic proteins such as NMDA-NR2A, NR2B, AMPA-GluR1, PSD-93 and PSD-95 were significantly decreased in hippocampus, with significant loss of dendritic spines. In keeping with these findings, high dose intake of zinc resulted in decreased hippocampal BDNF level and TrkB neurotrophic signaling. At last, increasing the brain zinc level directly by brain zinc injection induced BDNF expression, which was reversed by zinc chelating in vivo. These results indicate that zinc plays an important role in hippocampus-dependent learning and memory and BDNF expression, high dose supplementation of zinc induces specific zinc deficiency in hippocampus, which further impair learning and memory due to decreased availability of synaptic zinc and BDNF deficit.
Asunto(s)
Hipocampo/efectos de los fármacos , Hipocampo/fisiopatología , Trastornos de la Memoria/inducido químicamente , Transducción de Señal/efectos de los fármacos , Zinc/deficiencia , Zinc/toxicidad , Análisis de Varianza , Animales , Western Blotting , Factor Neurotrófico Derivado del Encéfalo/metabolismo , Suplementos Dietéticos , Homólogo 4 de la Proteína Discs Large , Relación Dosis-Respuesta a Droga , Guanilato-Quinasas/metabolismo , Hipocampo/metabolismo , Técnicas Histológicas , Masculino , Proteínas de la Membrana/metabolismo , Ratones , Ratones Endogámicos ICR , Receptor trkB/metabolismo , Receptores AMPA/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Transducción de Señal/fisiología , Zinc/administración & dosificaciónRESUMEN
The activity of protein phosphatase (PP) 2A is downregulated and promotes the hyperphosphorylation of tau in the brains of Alzheimer's disease (AD), but the mechanism for PP2A inactivation has not been elucidated. We have reported that PP2A phosphorylation at tyrosine 307 (Y307) is involved in PP2A inactivation. Here, we further studied the upstream mechanisms for PP2A phosphorylation and inactivation. We found that zinc, a heavy metal ion that is widely distributed in the normal brain and accumulated in the susceptible regions of AD brain, could induce PP2A inhibition, phosphorylation of PP2A at Y307 and tau hyperphosphorylation both in rat brains and cultured N2a cells, while zinc chelating prevented these changes completely. Upregulation of PP2A chemically or genetically attenuated zinc-induced tau hyperphosphorylation, whereas mutation of Y307 to phenylalanine abolished the zinc-induced tyrosine phosphorylation and inactivation of PP2A. Zinc could activate Src, while PP2, a specific Src family kinases inhibitor, attenuated zinc-induced PP2A phosphorylation and inactivation, indicating that zinc induces PP2A Y307 phosphorylation and inactivation through Src activation. In human tau transgenic mice, zinc chelator rescued PP2A activity, prevented Src activation, and reduced hyperphosphorylated and insoluble tau levels. We concluded that zinc induces PP2A inactivation and tau hyperphosphorylation through Src-dependent pathway, regulation of zinc homeostasis may be a promising therapeutic for AD and the related tauopathies.
Asunto(s)
Encéfalo , Proteína Fosfatasa 2 , Tauopatías/metabolismo , Oligoelementos/farmacología , Zinc/farmacología , Familia-src Quinasas , Proteínas tau , Animales , Encéfalo/efectos de los fármacos , Encéfalo/metabolismo , Línea Celular Tumoral , Humanos , Ratones , Ratones Transgénicos , Neuronas/efectos de los fármacos , Neuronas/metabolismo , Fosforilación/efectos de los fármacos , Fosforilación/fisiología , Proteína Fosfatasa 2/efectos de los fármacos , Proteína Fosfatasa 2/metabolismo , Pirimidinas/farmacología , Ratas , Ratas Sprague-Dawley , Tirosina/efectos de los fármacos , Tirosina/metabolismo , Familia-src Quinasas/efectos de los fármacos , Familia-src Quinasas/metabolismo , Proteínas tau/efectos de los fármacos , Proteínas tau/metabolismoRESUMEN
Hyperphosphorylated tau is the major component of neurofibrillary tangles in Alzheimer disease (AD), and the tangle distribution largely overlaps with zinc-containing glutamatergic neurons, suggesting that zinc released in synaptic terminals may play a role in tau phosphorylation. To explore this possibility, we treated cultured hippocampal slices or primary neurons with glutamate or Bic/4-AP to increase the synaptic activity with or without pretreatment of zinc chelators, and then detected the phosphorylation levels of tau. We found that glutamate or Bic/4-AP treatment caused tau hyperphosphorylation at multiple AD-related sites, including Ser-396, Ser-404, Thr-231, and Thr-205, while application of intracellular or extracellular zinc chelators, or blockade of zinc release by extracellular calcium omission almost abolished the synaptic activity-associated tau hyperphosphorylation. The zinc release and translocation of excitatory synapses in the hippocampus were detected, and zinc-induced tau hyperphosphorylation was also observed in cultured brain slices incubated with exogenously supplemented zinc. Tau hyperphosphorylation induced by synaptic activity was strongly associated with inactivation of protein phosphatase 2A (PP2A), and this inactivation can be reversed by pretreatment of zinc chelator. Together, these results suggest that synaptically released zinc promotes tau hyperphosphorylation through PP2A inhibition.