Insecticidal action of mammalian galectin-1-transfected Arabidopsis thaliana.

BACKGROUND: Galectins (GALs) are a family of mammalian sugar-binding proteins specific for ß-galactosides. Our previous studies have shown that the larval development of the diamondback moth (Plutella xylostella) is significantly disturbed when fed with recombinant mammalian galectin 1 (GAL1) derived from Escherichia coli. To further explore its applicability, two GAL1-overexpressed Arabidopsis [GAL1-Arabidopsis (whole plant) and GAL1-Arabidopsis-vas (vascular bundle-specific)] lines were established for insecticidal activity and mechanism studies. RESULTS: The expression level of GAL1 in transgenic Arabidopsis is 1-0.5% (GAL1-Arabidopsis) and 0.08-0.01% (GAL1-Arabidopsis-vas) of total leaf soluble protein. Survival, body weight, and food consumption significantly decreased in a time-dependent manner in P. xylostella larvae (with chewing mouthparts) fed on GAL1-Arabidopsis. The mortality of Kolla paulula (with piercing-sucking mouthparts and xylem feeder) fed on GAL1-Arabidopsis-vas was also significantly higher than that fed on wild-type Arabidopsis (WT-Arabidopsis), but was lower than that fed on GAL1-Arabidopsis. The histochemical structure and results of immunostaining suggested that the binding of GAL1 to the midgut epithelium of P. xylostella fed on GAL1-Arabidopsis was dose- and time-dependent. Ultrastructural studies further showed the disruption of microvilli, abnormalities in epithelial cells, and fragments of the peritrophic membrane (PM) in P. xylostella larvae fed on GAL1-Arabidopsis. CONCLUSION: The insecticidal mechanism of GAL1 involves interference with PM integrity and suggests that GAL1 is a potential candidate for bioinsecticide development. © 2024 Society of Chemical Industry.

Enhancing the insecticidal potential of a baculovirus by overexpressing the mammalian ß-galactosyl binding protein galectin-1.

BACKGROUND: Bio-pesticide development is an important area of research in agriculture, in which viruses are an essential tool. Infection by entomological pathogenic viruses kills agricultural pests, and viral progenies are disseminated to infect more pests, eventually achieving long-term pest control in the field. Of the current virus-based pest control models, Autographa californica multiple nucleopolyhedrovirus (AcMNPV) is the most studied. AcMNPV belongs to the Baculoviridae family and can infect many lepidopterans. Although AcMNPV has been previously demonstrated to be a potential pest-control tool, its long virus infection cycle has made field applications challenging. To overcome this, we generated a recombinant baculovirus that can express mammalian galectin-1, which is a galactoside-binding protein that binds to the peritrophic matrix in the midgut of lepidopteran pests and induces perforation of the membrane. RESULTS: Hosts infected with a recombinant virus that expressed mammalian galectin-1 exhibited reduced appetite and died sooner in both laboratory and small-scale field studies, suggesting that the overexpression of galectin-1 can more efficiently eliminate pest hosts. In addition to disrupting the integrity of the peritrophic matrix, the immune system of hosts infected with recombinant baculovirus carrying the galectin-1 gene was suppressed, making hosts more vulnerable to secondary infection. CONCLUSION: Galectin-1 has been shown to affect immune responses in mammals, including humans, but to our knowledge, the effect of galectin-1 on insect immune systems had not been previously reported. Our results demonstrated that the pest-control potential of baculoviruses can be improved by using a recombinant baculovirus that overexpresses mammalian galectin-1 in hosts. © 2022 Society of Chemical Industry.

Chemical identification of an active component and putative neural mechanism for repellent effect of a native ant's odor on invasive species.

The invasive Argentine ants (Linepithema humile) and the red imported fire ants (Solenopsis invicta) constitute a worldwide threat, causing severe disruption to ecological systems and harming human welfare. In view of the limited success of current pest control measures, we propose here to employ repellents as means to mitigate the effect of these species. We demonstrate that cuticular hydrocarbons (CHCs) used as nestmate-recognition pheromone in the Japanese carpenter ant (Camponotus japonicus), and particularly its (Z)-9-tricosene component, induced vigorous olfactory response and intense aversion in these invasive species. (Z)-9-Tricosene, when given to their antennae, caused indiscriminate glomerular activation of antennal lobe (AL) regions, creating neural disarray and leading to aversive behavior. Considering the putative massive central neural effect, we suggest that the appropriate use of certain CHCs of native ants can facilitate aversive withdrawal of invasive ants.

Modeling geographical invasions of Solenopsis invicta influenced by land-use patterns.

Research into geographical invasions of red imported fire ants (RIFAs) by anthropogenic disturbances has received much attention. However, little is known about how land-use change and the characteristics of roads with different land-use types are associated with the risk of RIFA successful invasion or remaining at the highest level of invasion (RIFA SIRH). Furthermore, it was often assumed in prior studies that the risk of RIFA SIRH had a linear association with the independent variables. However, a linear relationship may not reflect the actual circumstances. In this study, we applied linear and nonlinear approaches to assess how land-use types, distance from the nearest road, different land-use types, and spatial factors affect the risk of RIFA SIRH. The results showed that agricultural land, land for transportation usage, and areas that had undergone land-use change from 2014 to 2017 had greater odds of RIFA invasion than natural land cover. We also identified land for transportation usage and the area of land-use change from 2014 to 2017, had more than 60% of RIFA SIRH within 350 m and 150 m from the nearest road. This study provided important insights into RIFA invasions in an isolated island and the areas of control strategies implemented.

Exposure to PM2.5 induces neurotoxicity, mitochondrial dysfunction, oxidative stress and inflammation in human SH-SY5Y neuronal cells.

Ambient air pollution is a global public health issue. Recent evidence suggests that exposure to fine aerosolized particulate matter (PM) as small as ≤2.5 microns (PM2.5) is neurotoxic to brain structures. Many studies also suggest exposure to PM2.5 may cause neurotoxicity and affect brain function. However, the molecular mechanisms by which PM2.5 exerts these effects are not fully understood. Thus, we evaluated the hypothesis that PM2.5 exposure exerts its neurotoxic effects via increased oxidative and inflammatory cellular damage and mitochondrial dysfunction using human SH-SY5Y neuronal cells. Here, we show PM2.5 exposure significantly decreases viability, and increases caspase 3 and 9 protein expression and activity in SH-SY5Y cells. In addition, PM2.5 exposure decreases SH-SY5Y survival, disrupts cell and mitochondrial morphology, and significantly decreases ATP levels, D-loop levels, and mitochondrial mass and function (maximal respiratory function, COX activity, and mitochondrial membrane potential) in SH-SY5Y cells. Moreover, SH-SY5Y cells exposed to PM2.5 have significantly decreased mRNA and protein expression levels of survival genes (CREB and Bcl-2) and neuroprotective genes (PPARγ and AMPK). We further show SH-SY5Y cells exposure to PM2.5 induces significant increases in the levels of oxidative stress, and expression levels of the inflammatory mediator's TNF-α, IL-1ß, and NF-κB. Taken together, these results provide the first evidence of the biochemical, molecular and morphological effects of PM2.5 on human neuronal SH-SY5Y cells, and support our hypothesis that increased mitochondrial disruption, oxidative stress and inflammation are critical mediators of its neurotoxic effects. These findings further improve our understanding of the neuronal cell impact of PM2.5 exposure, and may be useful in the design of strategies for the treatment and prevention of human neurodegenerative disorders.

TO901317 activation of LXR-dependent pathways mitigate amyloid-beta peptide-induced neurotoxicity in 3D human neural stem cell culture scaffolds and AD mice.

Alzheimer's disease (AD) is the major cause of neurodegeneration worldwide and is characterized by the accumulation of amyloid beta (Aß) in the brain, which is associated with neuronal loss and cognitive impairment. Liver X receptor (LXR), a critical nuclear receptor, and major regulator in lipid metabolism and inflammation, is suggested to play a protective role against the mitochondrial dysfunction noted in AD. In our study, our established 3D gelatin scaffold model and a well characterized in vivo (APP/PS1) murine model of AD were used to directly investigate the molecular, biochemical and behavioral effects of neuronal stem cell exposure to Aß to improve understanding of the in vivo etiology of AD. Herein, human neural stem cells (hNSCs) in our 3D model were exposed to Aß, and had significantly decreased cell viability, which correlated with decreased mRNA and protein expression of LXR, Bcl-2, CREB, PGC1α, NRF-1, and Tfam, and increased caspase 3 and 9 activities. Cotreatment with a synthetic agonist of LXR (TO901317) significantly abrogated these Aß-mediated effects in hNSCs. Moreover, TO901317 cotreatment both significantly rescues hNSCs from Aß-mediated decreases in ATP levels and mitochondrial mass, and significantly restores Aß-induced fragmented mitochondria to almost normal morphology. TO901317 cotreatment also decreases tau aggregates in Aß-treated hNSCs. Importantly, TO901317 treatment significantly alleviates the impairment of memory, decreases Aß aggregates and increases proteasome activity in APP/PS1 mice; whereas, these effects were blocked by cotreatment with an LXR antagonist (GSK2033). Together, these novel results improve our mechanistic understanding of the central role of LXR in Aß-mediated hNSC dysfunction. We also provide preclinical data unveiling the protective effects of using an LXR-dependent agonist, TO901317, to block the toxicity observed in Aß-exposed hNSCs, which may guide future treatment strategies to slow or prevent neurodegeneration in some AD patients.

Transcriptome profiling reveals the developmental regulation of NaCl-treated Forcipomyia taiwana eggs.

BACKGROUND: The biting midge, Forcipomyia taiwana, is one of the most annoying blood-sucking pests in Taiwan. Current chemical control methods only target the adult, not the immature stages (egg to pupa), of F. taiwana. Discovering new or alternative tactics to enhance or replace existing methods are urgently needed to improve the effectiveness of F. taiwana control. The egg is the least understood life stage in this pest species but may offer a novel point of control as addition of NaCl to the egg environment inhibits development. Thus, the objective of this study was to use RNA profiling to better understand the developmental differences between wild-type melanized (black) and NaCl-induced un-melanized (pink), infertile F. taiwana eggs. RESULTS: After de novo assembly with Trinity, 87,415 non-redundant transcripts (Ft-nr) with an N50 of 1099 were obtained. Of these, 26,247 (30%) transcripts were predicted to have long open reading frames (ORFs, defined here as ≥300 nt) and 15,270 (17.5%) transcripts have at least one predicted functional domain. A comparison between two biological replicates each of black and pink egg samples, although limited in sample size, revealed 5898 differentially expressed genes (DEGs; 40.9% of the transcripts with long ORFs) with ≥2-fold difference. Of these, 2030 were annotated to a Gene Ontology biological process and along with gene expression patterns can be separated into 5 clusters. KEGG pathway analysis revealed that 1589 transcripts could be assigned to 18 significantly enriched pathways in 2 main categories (metabolism and environmental information processing). As expected, most (88.32%) of these DEGs were down-regulated in the pink eggs. Surprisingly, the majority of genes associated with the pigmentation GO term were up-regulated in the pink egg samples. However, the two key terminal genes of the melanin synthesis pathway, laccase2 and DCE/yellow, were significantly down-regulated, and further verified by qRT-PCR. CONCLUSION: We have assembled and annotated the first egg transcriptome for F. taiwana, a biting midge. Our results suggest that down-regulation of the laccase2 and DCE/yellow genes might be the mechanism responsible for the NaCl-induced inhibition of melanization of F. taiwana eggs.

Establishment and Social Impacts of the Red Imported Fire Ant, Solenopsis invicta, (Hymenoptera: Formicidae) in Taiwan.

The first report of the red imported fire ant (RIFA), Solenopsis invicta Buren, in Taiwan was in the city of Taoyuan in 2003. The government has made great efforts to bring RIFA-infested areas under control. RIFA has gradually spread outward since its discovery, but it is still confined in northern Taiwan, in part due to the control efforts. RIFA is well established in densely populated environments (i.e., urban areas), causing damage to public utilities and significantly affects the inhabitants of Taiwan. Out of 10,127 human encounters with RIFA reported by the Plant Pest Information Management System in the Bureau of Animal and Plant Health Inspection and Quarantine, Council of Agriculture, Executive Yuan, 3819 (37.71%) persons were stung, with 834 (21.8%) persons exhibiting wheal-and-flare reaction (swelling and redness of the skin). Among the victims, 288 (7.5%) sought medical care, and about 21 (0.6%) developed severe cellulitis and urticaria. Unexpectedly, 2.8% (106) of the victims exhibited anaphylactic shock, which was higher than previously reported cases (1%). The high anaphylactic shock percentage was probably because most victims were elderly farmers or because Asian people have higher sensitivity to the RIFA sting. RIFA is well adapted to the environmental conditions in Taiwan, which makes it extremely difficult (if not impossible) to eradicate. The management of RIFA in the future should focus on lowering the speed of spread to mitigate possible dangers to the inhabitants. Six major challenges of RIFA management in Taiwan are also discussed.

Toxicity of Terahertz-Based Functional Mineral Water (Plant-Derived) to Immature Stages of Mosquito Vectors.

Functional mineral water and related products are popular in some Asian countries as health drinks and, recently, have been employed in agricultural crop production as well as pest control. This study aimed to investigate the survival of mosquito vectors exposed to plant-derived functional mineral water produced by terahertz technology. The terahertz-based functional mineral water used in the current study not only decreased the hatching of Culex quinquefasciatus (Say) larvae but also showed concentration-dependent toxicity to the 3rd instar larvae and pupae of the three mosquito species tested. Aedes albopictus (Skuse) and Cx. quinquefasciatus pupae were more susceptible to terahertz-based functional mineral water than the larval stage, as indicated by their lower LC50. Lower concentrations (<100 ppm) of terahertz-based functional mineral water were not lethal to the pupae; however, these low concentrations still resulted in a reduced adult emergence. Although terahertz-based functional mineral water did not significantly affect Aedes aegypti (Linnaeus) hatching, it could potentially be used for vector control at the larvae and pupae stages. The larvicidal and pupicidal activity of diluted terahertz-based functional mineral water gradually diminished after 24 h, indicating that it is a biodegradable and eco-friendly bioinsecticide. However, as the terahertz-based functional mineral water is also toxic to larvivorous predatory-copepods, it should not be utilized in aquatic environments where predatory-based mosquito control programs are employed.

Nanogold induces anti-inflammation against oxidative stress induced in human neural stem cells exposed to amyloid-beta peptide.

Alzheimer's disease (AD) is a neurodegenerative disorder with progressive memory loss resulting in dementia. Amyloid-beta (Aß) peptides play a critical role in the pathogenesis of the disease by promoting inflammation and oxidative stress, leading to neurodegeneration in the brains of AD patients. Numerous in vitro 3D cell culture models are useful mimics for understanding cellular changes that occur during AD under in vivo conditions. The 3D Bioprinter developed at the CELLINK INKREDIBLE was used in this study to directly investigate the influence of 3D conditions on human neural stem cells (hNSCs) exposed to Aß. The development of anti-AD drugs is usually difficult, mainly due to a lack of therapeutic efficacy and enhanced serious side effects. Gold nanoparticles (AuNPs) demonstrate benefits in the treatment of several diseases, including AD, and may provide a novel therapeutic approach for AD patients. However, the neuroprotective mechanisms by which AuNPs exert these beneficial effects in hNSCs treated with Aß are still not well understood. Therefore, we tested the hypothesis that AuNPs protect against Aß-induced inflammation and oxidative stress in hNSCs under 3D conditions. Here, we showed that AuNPs improved the viability of hNSCs exposed to Aß, which was correlated with the reduction in the expression of inflammatory cytokines, such as TNF-α and IL-1ß. In addition, AuNPs rescued the levels of the transcripts of inhibitory kappa B kinase (IKK) in Aß-treated hNSCs. The Aß-mediated increases in mRNA, protein, and nuclear translocation levels of NF-κB (p65), a key transcription factor involved in inflammatory responses, were all significantly abrogated following co-treatment of hNSCs with AuNPs. In addition, treatment with AuNPs significantly restored iNOS and COX-2 levels in Aß-treated hNSCs. Importantly, hNSCs co-treated with AuNPs were significantly protected from Aß-induced oxidative stress, as detected using the DCFH-DA and DHE staining assays. Furthermore, hNSCs co-treated with AuNPs were significantly protected from the Aß-induced reduction in the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and Nrf2 downstream antioxidant target genes (SOD-1, SOD-2, Gpx1, GSH, Catalase, and HO-1). Moreover, AuNPs reduced the aggregates and increased the proteasome activity and the expression of HSP27 and HSP70 genes in Aß-treated hNSCs. Taken together, these findings provide the first evidence extending our understanding of the molecular mechanisms under 3D scaffold conditions by which AuNPs reverse the inflammation and oxidative stress-induced in hNSCs exposed to Aß. These findings may facilitate the development of novel treatments for AD.

Elucidating how the red imported fire ant (Solenopsis invicta) diffused spatiotemporally among different landscapes in north Taiwan, 2008-2015.

Solenopsis invicta Buren, also known as the red imported fire ant (RIFA), has had a large negative impact on human and livestock health. However, few studies have further investigated the influence of human land use, which is an important factor affecting the habitats of insects, on the expansion of RIFAs. In addition, there is a lack of knowledge of the empirical associations between RIFA diffusion and land use within countries. Therefore, the objectives of this study were to provide an approach to delineate the areas of RIFA infestations and explore how land use influences the spatiotemporal diffusion of S. invicta. We used RIFA data from 2008 to 2015 from the RIFA surveillance system, which was conducted by the National RIFA Control Center in Taiwan. Two regions in Taiwan with different RIFA infestation levels were investigated. The ordinary kriging method was applied to show the spatial intensity of RIFAs, and the extreme distance estimator method was applied to determine the critical dispersal distances, which showed the distance of the highest probability of RIFAs in two consecutive years. In addition, network analyses were used to identify RIFA invasion routes between land-use types. Finally, bivariate local indicators of spatial association were used to capture the invasion process in time and space. The results showed, paddy fields, main roads, and warehouses were identified as the top three land-use types of diffusion sources. On average, the critical RIFA dispersal distances were 600 and 650 m in two consecutive years in high- and low-infestation regions, respectively. Finally, RIFAs were likely to diffuse between main roads and warehouses in the low-infestation region. Therefore, it is suggested that RIFA control activities be implemented at least 600 m from the observed spot. Additionally, control activities should be conducted on the identified three land-use types of diffusion sources in the high-infestation region, and the roadsides between main roads and warehouses in the low-infestation region to prevent the accidental spread of RIFAs.

Nanogold Neuroprotection in Human Neural Stem Cells Against Amyloid-beta-induced Mitochondrial Dysfunction.

Alzheimer's disease (AD) is a neuronal dementia with progressive memory loss. Amyloid-beta (Aß) peptides has major effect in the neurodegenerative disorder, which are thought to promote mitochondrial dysfunction in AD brains. Anti-AD drugs acting upon the brain are generally difficult to develop, often cause serious side effects or lack therapeutic efficacy. Numerous studies have shown the beneficial therapeutic applications of gold nanoparticles (AuNPs), including for neuroprotective events and AD. The aim of this study is to understand how AuNPs could exert their neuroprotective role in AD, for which cell model have chosen human neural stem cells (hNSCs) as the experimental tool. We hypothesize AuNPs protect against Aß-induced cellular impairment and mitochondrial dysfunction in hNSCs. Here, we show AuNPs increase the survival of hNSCs treated with Aß via downregulation of caspase 3 and 9 activities. Moreover, AuNPs abrogated the Aß-mediated decrease neuroprotective (CREB and Bcl-2) and mitochondrial (PGC1α, NRF-1 and Tfam) gene expressions in treated hNSCs. Importantly, co-treatment with AuNPs significantly rescued hNSCs from Aß-mediated mitochondrial function and morphology. AuNPs also significantly normalizes the immunostaining of mitochondrial marker and mass in differentiated hNSCs with Aß. The effects may be exerted by the AuNPs, as supported by its protective reversal of Aß-induced cellular impairment and mitochondrial dysfunction in hNSCs. In fact, the results presented extend our understanding of the mechanisms through which AuNPs could exert their neuroprotective role in hNSCs treated with Aß.

Phytochemical composition and larvicidal activity of essential oils from herbal plants.

MAIN CONCLUSION: The essential oils (EOs) of Plectranthus amboinicus showed the highest larvicidal activity among four herbal plants studied and ß-caryophyllene might be the major component responsible for its differential toxicity to the larvae of Culex quinquefasciatus and Aedes Aegypti. Mosquitoes act as vectors for many life-threatening diseases, including malaria, dengue fever, and Zika virus infection. Management of mosquitoes mainly relies on synthetic insecticides, which usually result in the rapid development of resistance; therefore, alternative mosquito control strategies are urgently needed. This study characterized the major component of essential oils (EOs) derived from the vegetative parts of four herbal plants and their larvicidal activity toward important mosquito vectors. The EOs were extracted by hydro-distillation and subjected to gas chromatography-mass spectrometry (GC-MS) analysis and a larvicidal activity assay toward Aedes aegypti, Ae. albopictus and Culex quinquefasciatus. In total, 14, 11, 11 and 9 compounds were identified from the EOs of Plectranthus amboinicus, Mentha requienii, Vitex rotundifolia and Crossostephium chinense, respectively. The EOs derived from four herbal plants exhibited remarkable larvicidal activity against the three mosquito species. In particular, the EOs of P. amboinicus showed the highest larvicidal activity, and the larvae of Cx. quinquefasciatus were more sensitive to the P. amboinicus EOs than that of Ae. Aegypti. Although carvacrol (61.53%) was the predominant constituent of the P. amboinicus EOs, its precursors, γ-terpinene (8.51%) and p-cymene (9.42%), exhibited the most larvicidal activity toward Ae. aegypti and Cx. quinquefasciatus. However, ß-caryophyllene (12.79%) might be the major component responsible for the differential toxicity of the P. amboinicus EOs, as indicated by the significant differences in its LC50 values toward both mosquitoes. Information from these studies will benefit the incorporation of EOs into integrated vector management.

Rosiglitazone rescues human neural stem cells from amyloid-beta induced ER stress via PPARγ dependent signaling.

Peroxisome proliferator-activated receptor gamma (PPARγ) belongs to a family of ligand-activated nuclear receptors known to regulate many crucial physiological and pathological conditions. Indeed, altered PPARγ transcriptional activity contributes to metabolic syndromes (obesity and hyperglycemia associated with type 2 diabetes mellitus), stroke and neurodegenerative diseases. Various studies suggest that PPARγ agonists influence neuronal deficits in Alzheimer's Disease (AD) patients and rodent models of AD. Expression of amyloid-beta (Aß), a neuropathological marker associated with the pathogenesis of AD neuronal impairment, is inversely correlated with the activation of PPARγ-dependent neuroprotective responses. Nevertheless, molecular mechanisms by which the effects of PPARγ agonists in AD remain to be clarified. Here, we explore the PPARγ signaling pathways and networks that protect against Aß-induced endoplasmic reticulum (ER) stress (e.g., caspase 4, Bip, CHOP, ASK1 and ER calcium), cell death (e.g., viability and cytochrome c) and mitochondrial deficiency (e.g., maximal respiratory function, COX activity, and mitochondrial membrane potential) events in the human neural stem cells (hNSCs) treated with Aß. Co-treatment with GW9662 (an antagonist of PPARγ) effectively blocked these protective effects by rosiglitazone, providing strong evidence that PPARγ-dependent signaling rescues hNSCs from Aß-mediated toxicity. Together, our data suggest activation of PPARγ pathway might be critical to protecting against AD-related ER stress, ER disequilibrium and mitochondrial deficiency. These findings also improve our understanding of the role of PPARγ in hNSCs, and may aid in the development and implementation of new therapeutic strategies for the treatment of AD.

Metformin activation of AMPK suppresses AGE-induced inflammatory response in hNSCs.

A growing body of evidence suggests type 2 diabetes mellitus (T2DM) is linked to neurodegenerative diseases such as Alzheimer's disease (AD). Although the precise mechanisms remain unclear, T2DM may exacerbate neurodegenerative processes. AMP-activated protein kinase (AMPK) signaling is an evolutionary preserved pathway that is important during homeostatic energy biogenesis responses at both the cellular and whole-body levels. Metformin, a ubiquitously prescribed anti-diabetic drug, exerts its effects by AMPK activation. However, while the roles of AMPK as a metabolic mediator are generally well understood, its performance in neuroprotection and neurodegeneration are not yet well defined. Given hyperglycemia is accompanied by an accelerated rate of advanced glycosylation end product (AGE) formation, which is associated with the pathogenesis of diabetic neuronal impairment and, inflammatory response, clarification of the role of AMPK signaling in these processes is needed. Therefore, we tested the hypothesis that metformin, an AMPK activator, protects against diabetic AGE induced neuronal impairment in human neural stem cells (hNSCs). In the present study, hNSCs exposed to AGE had significantly reduced cell viability, which correlated with elevated inflammatory cytokine expression, such as IL-1α, IL-1ß, IL-2, IL-6, IL-12 and TNF-α. Co-treatment with metformin significantly abrogated the AGE-mediated effects in hNSCs. In addition, metformin rescued the transcript and protein expression levels of acetyl-CoA carboxylase (ACC) and inhibitory kappa B kinase (IKK) in AGE-treated hNSCs. NF-κB is a transcription factor with a key role in the expression of a variety of genes involved in inflammatory responses, and metformin did prevent the AGE-mediated increase in NF-κB mRNA and protein levels in the hNSCs exposed to AGE. Indeed, co-treatment with metformin significantly restored inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) levels in AGE-treated hNSCs. These findings extend our understanding of the central role of AMPK in AGE induced inflammatory responses, which increase the risk of neurodegeneration in diabetic patients.

Metformin activation of AMPK-dependent pathways is neuroprotective in human neural stem cells against Amyloid-beta-induced mitochondrial dysfunction.

Alzheimer's disease (AD) is the general consequence of dementia and is diagnostic neuropathology by the cumulation of amyloid-beta (Aß) protein aggregates, which are thought to promote mitochondrial dysfunction processes leading to neurodegeneration. AMP-activated protein kinase (AMPK), a critical regulator of energy homeostasis and a major player in lipid and glucose metabolism, is potentially implied in the mitochondrial deficiency of AD. Metformin, one of the widespread used anti- metabolic disease drugs, use its actions in part by stimulation of AMPK. While the mechanisms of AD are well established, the neuronal roles for AMPK in AD are still not well understood. In the present study, human neural stem cells (hNSCs) exposed to Aß had significantly reduced cell viability, which correlated with decreased AMPK, neuroprotective genes (Bcl-2 and CREB) and mitochondria associated genes (PGC1α, NRF-1 and Tfam) expressions, as well as increased activation of caspase 3/9 activity and cytosolic cytochrome c. Co-treatment with metformin distinct abolished the Aß-caused actions in hNSCs. Metformin also significantly rescued hNSCs from Aß-mediated mitochondrial deficiency (lower D-loop level, mitochondrial mass, maximal respiratory function, COX activity, and mitochondrial membrane potential). Importantly, co-treatment with metformin significantly restored fragmented mitochondria to almost normal morphology in the hNSCs with Aß. These findings extend our understanding of the central role of AMPK in Aß-related neuronal impairment. Thus, a better understanding of AMPK might assist in both the recognition of its critical effects and the implementation of new therapeutic strategies in the treatment of AD.

Rosiglitazone activation of PPARγ-dependent signaling is neuroprotective in mutant huntingtin expressing cells.

Peroxisome proliferator-activated receptor gamma (PPARγ) is a crucial transcription factor for neuroprotection in several brain diseases. Using a mouse model of Huntington's Disease (HD), we recently showed that PPARγ not only played a major function in preventing HD, but also oral intake of a PPARγ agonist (thiazolidinedione, TZD) significantly reduced the formation of mutant Huntingtin (mHtt) aggregates in the brain (e.g., cortex and striatum). The molecular mechanisms by which PPARγ exerts its HD neuroprotective effects remain unresolved. We investigated whether the PPARγ agonist (rosiglitazone) mediates neuroprotection in the mHtt expressing neuroblastoma cell line (N2A). Here we show that rosiglitazone upregulated the endogenous expression of PPARγ, its downstream target genes (including PGC1α, NRF-1 and Tfam) and mitochondrial function in mHtt expressing N2A cells. Rosiglitazone treatment also significantly reduced mHtt aggregates that included ubiquitin (Ub) and heat shock factor 1 (HSF1), as assessed by a filter-retardation assay, and increased the levels of the functional ubiquitin-proteasome system (UPS), HSF1 and heat shock protein 27/70 (HSP27/70) in N2A cells. Moreover, rosiglitazone treatment normalized endoplasmic reticulum (ER) stress sensors Bip, CHOP and ASK1, and significantly increased N2A cell survival. Taken together, these findings unveil new insights into the mechanisms by which activation of PPARγ signaling protects against the HD-mediated neuronal impairment. Further, our data also support the concept that PPARγ may be a novel therapeutic target for treating HD.

Quantitative peptidomics study reveals that a wound-induced peptide from PR-1 regulates immune signaling in tomato.

Many important cell-to-cell communication events in multicellular organisms are mediated by peptides, but only a few peptides have been identified in plants. In an attempt to address the difficulties in identifying plant signaling peptides, we developed a novel peptidomics approach and used this approach to discover defense signaling peptides in plants. In addition to the canonical peptide systemin, several novel peptides were confidently identified in tomato (Solanum lycopersicum) and quantified to be induced by both wounding and methyl jasmonate (MeJA). A wounding or wounding plus MeJA-induced peptide derived from the pathogenesis-related protein 1 (PR-1) family was found to induce significant antipathogen and minor antiherbivore responses in tomato. This study highlights a role for PR-1 in immune signaling and suggests the potential application of plant endogenous peptides in efforts to defeat biological threats in crop production. As PR-1 is highly conserved across many organisms and the putative peptide from At-PR1 was also found to be bioactive in Arabidopsis thaliana, our results suggest that this peptide may be useful for enhancing resistance to stress in other plant species.

The forkhead transcription factor FOXO1 stimulates the expression of the adipocyte resistin gene.

Resistin is known as an adipocyte-specific hormone that can cause insulin resistance and decrease adipocyte differentiation. It can be regulated by transcriptional factors, but the possible role of forkhead transcription factor FOXO1 in regulating resistin gene expression is still unknown. Using 3T3 fibroblast and C3H10T1/2 and 3T3-L1 adipocytes, we found that transient overexpression of a non-phosphorylatable, constitutively active FOXO1, but not the wild type of FOXO1 or a DNA binding-deficient FOXO1, activated resistin promoter-directed luciferase expression. However, transient overexpression of a dominant-negative FOXO1 inactivated resistin promoter activity and reduced resistin mRNA expression. These observations indicate that the action of FOXO1 on resistin gene expression requires the activation of FOXO1 and that the effect of FOXO1 depends on the phosphorylation and dephosphorylation of FOXO1. The FOXO1 protein target sites on the resistin promoter were localized to the proximal -3545 to -787bp of 5'-flanking region of the resistin promoter. A chromatin immunoprecipitation assay also showed that FOXO1 bound the resistin promoter at nucleotide regions of -1539 to -1366bp and -1016 to -835bp, but not at the regions of -795 to -632bp. Results of this study suggest that FOXO1 transcription factor likely activates the expression of adipocyte resistin gene via direct association with the upstream resistin promoter.

An improved bioassay facilitates the screening of repellents against cat flea, Ctenocephalides felis (Siphonaptera: Pulicidae).

BACKGROUND: Repellents are a common method for preventing flea bites, making an effective system for flea repellent screening advantageous. We describe an improved technique to facilitate repellent activity screening of numerous plant-based Ctenocephalides felis (cat flea) repellents. RESULTS: Two long strips of filter paper were impregnated with test compounds (dissolved in ethanol) and ethanol only, respectively. After drying, the two filter papers were glued together along the long side and inserted into a glass tube containing non-fed cat fleas. The distribution of cat fleas in each half of the filter paper was recorded after 30 min to calculate repellency. Results showed that the essential oil of Cinnamomum osmophloeum (from leaf), Taiwania cryptomerioides (from heartwood) and Plectranthus amboinicus (from leaf) exhibits repellent activity against cat fleas in a dose dependent manner. Moreover, the repellent activities against cat fleas of 2% trans-cinnamaldehyde (the main constituent of Ci. osmophloeum essential oil) and 0.5% thymol (the main constituent of P. amboinicus essential oil) are 97.6% and 90.6%, and can persist for up to 4 and 8 h, respectively. These results are comparable to those of 15% DEET. CONCLUSION: The proposed screening technique can facilitate the pre-screening of numerous flea repellents for further evaluation on animal or human subjects.