Tau truncation is widely detected in Alzheimers disease brain. Caspases activation is suggested to play a significant role in tau truncation at Aspartate 421 (D421) according to their ability to cleave recombinant tau in vitro. Ample evidence has shown that caspase-6 is involved in cognitive impairment and expressed in AD brain. Reactive oxygen species (ROS) can lead to caspase-6 activation and correlate with AD. Here, we transfected human embryonic kidney 293 (HEK 293) cells with Tau 441 plasmid and investigated the role of caspase-6 and caspase-3 in ROS-mediated tau truncation. Our data demonstrated that H2O2 induced oxidative stress and increased tau truncation. Caspase-6 and caspase-3 activity also increased in a dose-dependent manner in HEK 293/Tau cells during H2O2 insult. When cells were treated with an ROS inhibitor N-acetyl-L-cysteine, tau truncation was significantly suppressed. Compared with H2O2 (100 ?M)/non-inhibitor group or single-inhibitor groups (z-VEID-fmk, caspase-6 inhibitor or z-DEVD-fmk, and caspase-3 inhibitor), tau truncation induced by H2O2 was effectively reduced in the combinative inhibitors group. Similar results were shown when cells were transfected with specific caspase-3 and caspase-6 siRNA. Inhibition of caspase-6 led to decline of caspase-3 activation. Taken together, our results suggest that the combination of caspase-6 and caspase-3 aggravates tau truncation at D421 induced by H2O2. Caspase-6 may play an important part in activating caspase-3. Further investigation of how the synergic role of caspase-6 and caspase-3 affects tau truncation may provide new visions for potential AD therapies.
Neural stem/progenitor cells (NSPCs) of the subgranular zone have been implicated in cognitive processes, which represent a potentially important source of regenerative medicine for the treatment of neurodegenerative diseases such as Alzheimers disease (AD). In our previous studies, ZY-1, a novel nicotinic analog, improved cognitive function in transgenic mice model of AD. However, the effect of ZY-1 on the NSPCs remains unclear. Here, we show that ZY-1 significantly increased proliferation and migration of NSPCs, but failed to affect NSPCs differentiation in vitro. Furthermore, during the proliferative period, ZY-1 enhanced intracellular reactive oxygen species (ROS) levels. Meanwhile, ZY-1 also inhibited the levels of A?42-induced ROS. Our data indicate that ZY-1 regulates adult hippocampal neurogenesis in vitro, at least partly due to modulating intracellular ROS levels. These results, taken together with those of our previous studies, suggest that ZY-1 might have a potential therapeutic effect for the treatment of AD.
Alzheimers disease (AD) is characterized by a deficit in motor and spatial learning-memory and alteration of non-cognitive behavior. The generation of transgenic mice with presence of AD pathologies that cause learning and memory deficits has led to improved understanding of the behavioral and pathophysiological processes underlying AD. A novel APP/PS1 mouse model in the senescence accelerated mouse prone 8 (SAMP8) background - SAMP8 APP/PS1 was generated. To assess the behavioral and other AD-related changes in this SAMP8 APP/PS1 model, the present report covers a phenotypical analysis of this model for working memory, spatial memory, motor performance and anxiety-like behavior. SAMP8 APP/PS1 mice showed motor and spatial memory impairments, together with an increase of locomotor activity and lower anxiety-like behavior at 9months old. In contrast, C57 APP/PS1 and SAMP8 wild type mice were inconspicuous in all of these tasks and properties except C57 APP/PS1 mice which showed motor memory impairment in the shuttle box task at 9months old. Standard senescence-associated beta-galactosidase (SA-beta-GAL) staining and amyloid beta (A?) immunohistochemistry showed more severe pathological changes in the SAMP8 APP/PS1 mice. SAMP8 APP/PS1 mice exhibited earlier deficits in their non-cognitive and cognitive behaviors which are coincident in the AD patient and the results suggest that this new type of mice might be a better model for studying the age-related dementia of the Alzheimer type and for assessing the potential therapeutic agents for AD.
The APP/PS1 mouse model of Alzheimers disease (AD) exhibits remarkable elevation of ?-amyloid production associated with certain behavioral abnormalities, while the senescence accelerated mouse prone 8 (SAMP8) is characterized by early and age-related deterioration of learning and memory. In order to obtain an AD model that develops earlier pathological changes and cognitive impairment, we generated SAMP8-APP/PS1, a novel senescence accelerated APP/PS1 transgenic mouse model of AD. Standard histological staining and immunohistochemistry using an amyloid beta (A?) antibody showed an age, genotype and strain-dependent progression of amyloid deposition and neuron loss in the cerebral cortex and hippocampus of SAMP8-APP/PS1 mice. Results from the cognitive behavioral tests revealed early deficits in learning and memory in SAMP8-APP/PS1 mice in the two way active avoidance and Morris water maze tests compared with C57-APP/PS1, SAMP8 wild-type and control mice. These results suggest that accelerated senescence exacerbates amyloid deposition and cognitive dysfunction in APP/PS1 mice and the senescence accelerated-APP/PS1 (SAMP8-APP/PS1) mouse model might be a valuable tool to study AD progression and to evaluate the effect of drugs on AD.
Haloferax mediterranei is able to accumulate the bioplastic poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) with more than 10 mol% 3-hydroxyvalerate (3HV) from unrelated carbon sources. However, the pathways that produce propionyl coenzyme A (propionyl-CoA), an important precursor of 3HV monomer, have not yet been determined. Bioinformatic analysis of H. mediterranei genome indicated that this strain uses multiple pathways for propionyl-CoA biosynthesis, including the citramalate/2-oxobutyrate pathway, the aspartate/2-oxobutyrate pathway, the methylmalonyl-CoA pathway, and a novel 3-hydroxypropionate pathway. Cofeeding of pathway intermediates and inactivating pathway-specific genes supported that these four pathways were indeed involved in the biosynthesis of 3HV monomer. The novel 3-hydroxypropionate pathway that couples CO2 assimilation with PHBV biosynthesis was further confirmed by analysis of (13)C positional enrichment in 3HV. Notably, (13)C metabolic flux analysis showed that the citramalate/2-oxobutyrate pathway (53.0% flux) and the 3-hydroxypropionate pathway (30.6% flux) were the two main generators of propionyl-CoA from glucose. In addition, genetic perturbation on the transcriptome of the ?phaEC mutant (deficient in PHBV accumulation) revealed that a considerable number of genes in the four propionyl-CoA synthetic pathways were significantly downregulated. We determined for the first time four propionyl-CoA-supplying pathways for PHBV production in haloarchaea, particularly including a new 3-hydroxypropionate pathway. These results would provide novel strategies for the production of PHBV with controllable 3HV molar fraction.
In this paper, several different fermentation experiments were designed to address whether modulating glucose and propanol feeds could benefit the production level of erythromycin during pilot plant (30 L) fermentation. Results showed that glucose feed rate (determined by a set high or low culture pH) had no effect on erythromycin production, indicating that glucose was not the limiting factor for erythromycin biosynthesis under these conditions. It was found that decreasing glucose feed could stimulate the consumption of propanol, and the high erythromycin production (12.49 ± 0.50 mg ml?¹) was achieved by controlling the feed rates of glucose and propanol. The quantitative metabolic flux analysis disclosed that high propanol consumption increased the pool size of propionyl-CoA (~2.147 mmol g?¹ day?¹) and methylmalonyl-CoA (~1.708 mmol g?¹ day?¹). It was also found that 45-77 % of the propanol went into the TCA cycle which strengthened the conclusion that blocking the propionate pathway to TCA cycle could lead to a significant increase in erythromycin production in carbohydrate-based media (Reeves et al. Ind Microbiol Biotechnol 7:600-609, 2006). In addition, the results also suggested that a relative low intracellular ATP level resulting from low glucose feed did not limit the erythromycin biosynthesis, and a relatively high NADPH should be beneficial for erythromycin biosynthesis.
Alzheimers disease (AD) is a neurodegenerative disorder marked by progressive loss of memory and cognitive function. One of the new approaches for treating AD is direct stimulation of nicotinic acetylcholine receptors (nAChRs) in the brain. ?4?2-nAChR agonists have shown promising potential in preclinical cognition models of AD. The present report describes the pharmacological properties of ZY-1, a new nicotinic analogue that activates ?4?2-nAChR. We describe in detail the binding profile and pharmacological effects of ZY-1 on transgenic AD mice. ZY-1 has high affinity to ?4?2-nAChR. In a Morris water maze test, ZY-1 significantly decreases the escape latency and increases both the times in the platform quadrant and the times of platform crossing of transgenic mice. ZY-1 enhances cognitive functions in transgenic mice models of AD. As a novel nicotinic analogue, ZY-1 deserves further study as a potential candidate against AD.
In this study, the effects of nitrogen sources on broth viscosity and glucose consumption in erythromycin fermentation were investigated. By controlling ammonium sulfate concentration, broth viscosity and glucose consumption were decreased by 18.2% and 61.6%, respectively, whereas erythromycin biosynthesis was little affected. Furthermore, erythromycin A production was increased by 8.7% still with characteristics of low broth viscosity and glucose consumption through the rational regulations of phosphate salt, soybean meal and ammonium sulfate. It was found that ammonium sulfate could effectively control proteinase activity, which was correlated with the utilization of soybean meal as well as cell growth. The pollets formation contributed much to the decrease of broth viscosity. The accumulation of extracellular propionate and succinate under the new regulation strategy indicated that higher propanol consumption might increase the concentration of methylmalonyl-CoA and propionyl-CoA and thus could increase the flux leading to erythromycin A.
Irradiation commonly causes long-term bone marrow injury charactertized by defective HSC self-renewal and a decrease in HSC reserve. However, the effect of high-dose IR on global gene expression during bone marrow recovery remains unknown.
Panaxydol, a polyacetylene compound isolated from Panax ginseng, exerts anti-proliferative effects against malignant cells. No previous study, however, has been reported on its effects on hepatocellular carcinoma cells. Here, we investigated the effects of panaxydol on the proliferation and differentiation of human hepatocarcinoma cell line HepG2. We studied by electronic microscopy of morphological and ultrastructural changes induced by panaxydol. We also examined the cytotoxicities of panaxydol against HepG2 cells using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl tetrazolium bromide assay and the effect of panaxydol on cell cycle distributions by flow cytometry. We investigated the production of liver proteins in panaxydol-treated cells including alpha-fetoprotein and albumin and measured the specific activity of alkaline phosphatase and gamma-glutamyl transferase. We further investigated the effects of panaxydol on the expression of Id-1, Id-2, p21 and pRb by RT-PCR or immunoblotting analysis. We found that panaxydol inhibited the proliferation of HepG2 cells and caused morphological and ultrastructural changes in HepG2 cells resembling more mature forms of hepatocytes. Moreover, panaxydol induced a cell cycle arrest at the G(1) to S transition in HepG2 cells. It also significantly decreased the secretion of alpha-fetoprotein and the activity of gamma-glutamyl transferase. By contrast, panaxydol remarkably increased the secretion of albumin and the alkaline phosphatase activity. Furthermore, panaxydol increased the mRNA content of p21 while reducing that of Id-1 and Id-2. Panaxydol also increased the protein levels of p21, pRb and the hypophosphorylated pRb in a dose-dependent manner. These findings suggest that panaxydol is of value for further exploration as a potential anti-cancer agent.
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