Neonicotinoids are widely used systemic insecticides which, when applied to flowering crops, are translocated to the nectar and pollen where they may impact upon pollinators. Given global concerns ...over pollinator declines, this potential impact has recently received much attention. Field exposure of pollinators to neonicotinoids depends on the concentrations present in flowering crops and the degree to which pollinators choose to feed upon them. Here we describe a simple experiment using paired yellow pan traps with or without insecticide to assess whether the commonly used neonicotinoid imidacloprid repels or attracts flying insects. Both Diptera and Coleoptera exhibited marked avoidance of traps containing imidacloprid at a field-realistic dose of 1 µg L(-1), with Diptera avoiding concentrations as low as 0.01 µg L(-1). This is to our knowledge the first evidence for any biological activity at such low concentrations, which are below the limits of laboratory detection using most commonly available techniques. Catch of spiders in pan traps was also slightly reduced by the highest concentrations of imidacloprid used (1 µg L(-1)), but catch was increased by lower concentrations. It remains to be seen if the repellent effect on insects occurs when neonicotinoids are present in real flowers, but if so then this could have implications for exposure of pollinators to neonicotinoids and for crop pollination.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
is an Alzheimer's disease (AD) risk gene expressed in microglia. To study the role of
in a mouse model of β-amyloidosis, we compared PS2APP transgenic mice versus PS2APP mice lacking
(PS2APP;Trem2
) ...at ages ranging from 4 to 22 months. Microgliosis was impaired in PS2APP;Trem2
mice, with
-deficient microglia showing compromised expression of proliferation/Wnt-related genes and marked accumulation of ApoE. Plaque abundance was elevated in PS2APP;Trem2
females at 6-7 months; but by 12 or 19-22 months of age, it was notably diminished in female and male PS2APP;Trem2
mice, respectively. Across all ages, plaque morphology was more diffuse in PS2APP;Trem2
brains, and the Aβ42:Aβ40 ratio was elevated. The amount of soluble, fibrillar Aβ oligomers also increased in PS2APP;Trem2
hippocampi. Associated with these changes, axonal dystrophy was exacerbated from 6 to 7 months onward in PS2APP;Trem2
mice, notwithstanding the reduced plaque load at later ages. PS2APP;Trem2
mice also exhibited more dendritic spine loss around plaque and more neurofilament light chain in CSF. Thus, aggravated neuritic dystrophy is a more consistent outcome of
deficiency than amyloid plaque load, suggesting that the microglial packing of Aβ into dense plaque is an important neuroprotective activity.
Genetic studies indicate that
gene mutations confer increased Alzheimer's disease (AD) risk. We studied the effects of
deletion in the PS2APP mouse AD model, in which overproduction of Aβ peptide leads to amyloid plaque formation and associated neuritic dystrophy. Interestingly, neuritic dystrophies were intensified in the brains of
-deficient mice, despite these mice displaying reduced plaque accumulation at later ages (12-22 months). Microglial clustering around plaques was impaired, plaques were more diffuse, and the Aβ42:Aβ40 ratio and amount of soluble, fibrillar Aβ oligomers were elevated in
-deficient brains. These results suggest that the Trem2-dependent compaction of Aβ into dense plaques is a protective microglial activity, limiting the exposure of neurons to toxic Aβ species.
The gene GPNMB is known to play roles in phagocytosis and tissue repair, and is upregulated in microglia in many mouse models of neurodegenerative disease as well as in human patients. Nearby genomic ...variants are associated with both elevated Parkinson's disease (PD) risk and higher expression of this gene, suggesting that inhibiting GPNMB activity might be protective in Parkinson's disease. We tested this hypothesis in three different mouse models of neurological diseases: a remyelination model and two models of alpha-synuclein pathology. We found that Gpnmb deletion had no effect on histological, cellular, behavioral, neurochemical or gene expression phenotypes in any of these models. These data suggest that Gpnmb does not play a major role in the development of pathology or functional defects in these models and that further work is necessary to study its role in the development or progression of Parkinson's disease.
•GPNMB is activated in microglia in many neurodegenerative disease conditions.•Parkinson's disease risk and elevated GPNMB expression have moderate probability of genetic colocalization.•This suggests that inhibiting GPNMB may be protective for Parkinson's.•However, knocking out GPNMB in two synuclein models had no impact on any phenotype.
The development of alpha7 nicotinic acetylcholine receptor agonists is considered a promising approach for the treatment of cognitive symptoms in schizophrenia patients. In the present studies we ...characterized the novel agent, (2R)-N-(6-(1H-imidazol-1-yl)-4-pyrimidinyl)-4'H-spiro4-azabicyclo2.2.2octane-2,5'-1,3oxazol-2'-amine (BMS-933043), in vitro and in rodent models of schizophrenia-like deficits in cognition and sensory processing. BMS-933043 showed potent binding affinity to native rat (Ki = 3.3 nM) and recombinant human alpha7 nicotinic acetylcholine receptors (Ki = 8.1 nM) and agonist activity in a calcium fluorescence assay (EC50 = 23.4 nM) and whole cell voltage clamp electrophysiology (EC50 = 0.14 micromolar (rat) and 0.29 micromolar (human)). BMS-933043 exhibited a partial agonist profile relative to acetylcholine; the relative efficacy for net charge crossing the cell membrane was 67% and 78% at rat and human alpha7 nicotinic acetylcholine receptors respectively. BMS-933043 showed no agonist or antagonist activity at other nicotinic acetylcholine receptor subtypes and was at least 300 fold weaker at binding to and antagonizing human 5-HT3A receptors (Ki = 2,451 nM; IC50 = 8,066 nM). BMS-933043 treatment i) improved 24 hour novel object recognition memory in mice (0.1-10 mg/kg, sc), ii) reversed MK-801-induced deficits in Y maze performance in mice (1-10 mg/kg, sc) and set shift performance in rats (1-10 mg/kg, po) and iii) reduced the number of trials required to complete the extradimensional shift discrimination in neonatal PCP treated rats performing the intra-dimensional/extradimensional set shifting task (0.1-3 mg/kg, po). BMS-933043 also improved auditory gating (0.56-3 mg/kg, sc) and mismatch negativity (0.03-3 mg/kg, sc) in rats treated with S(+)ketamine or neonatal phencyclidine respectively. Given this favorable preclinical profile BMS-933043 was selected for further development to support clinical evaluation in humans.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Filamentous inclusions of the microtubule-associated protein, tau, define a variety of neurodegenerative diseases known as tauopathies, including Alzheimer's disease (AD). To better understand the ...role of tau-mediated effects on pathophysiology and global central nervous system function, we extensively characterized gene expression, pathology and behavior of the rTg4510 mouse model, which overexpresses a mutant form of human tau that causes Frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17). We found that the most predominantly altered gene expression pathways in rTg4510 mice were in inflammatory processes. These results closely matched the causal immune function and microglial gene-regulatory network recently identified in AD. We identified additional gene expression changes by laser microdissecting specific regions of the hippocampus, which highlighted alterations in neuronal network activity. Expression of inflammatory genes and markers of neuronal activity changed as a function of age in rTg4510 mice and coincided with behavioral deficits. Inflammatory changes were tau-dependent, as they were reversed by suppression of the tau transgene. Our results suggest that the alterations in microglial phenotypes that appear to contribute to the pathogenesis of Alzheimer's disease may be driven by tau dysfunction, in addition to the direct effects of beta-amyloid.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Parkinson's disease (PD), a neurodegenerative disease affecting dopaminergic (DA) neurons, is characterized by decline of motor function and cognition. Dopaminergic cell loss is associated with ...accumulation of toxic alpha synuclein aggregates. As DA neuron death occurs late in the disease, therapeutics that block the spread of alpha synuclein may offer functional benefit and delay disease progression. To test this hypothesis, we generated antibodies to the C terminal region of synuclein with high nanomolar affinity and characterized them in in vitro and in vivo models of spread. Interestingly, we found that only antibodies with high affinity to the distal most portion of the C-terminus robustly reduced uptake of alpha synuclein preformed fibrils (PFF) and accumulation of phospho (S129) alpha synuclein in cell culture. Additionally, the antibody treatment blocked the spread of phospho (S129) alpha synuclein associated-pathology in a mouse model of synucleinopathy. Blockade of neuronal PFF uptake by different antibodies was more predictive of in vivo activity than their binding potency to monomeric or oligomeric forms of alpha synuclein. These data demonstrate that antibodies directed to the C-terminus of the alpha synuclein have differential effects on target engagement and efficacy. Furthermore, our data provides additional support for the development of alpha synuclein antibodies as a therapeutic strategy for PD patients.
•Lewy bodies and neurites composed of aggregated alpha synuclein protein are the hallmarks of Parkinson's disease.•Preformed fibrils of alpha-synuclein can seed recruitment of endogenous synuclein into aggregates and spread from cell to cell.•Preformed fibrils of alpha synuclein bind to neurons , are taken up into the cells, causing phosphorylation of alpha synuclein.•In vitro screening identified anti-alpha synuclein antibodies that block uptake of PFFs into neurons also bind to the c-terminus of alpha synuclein.•High affinity c-terminal-targeting antibodies blocked alpha synuclein spread in vivo.
Global proteomics of Ubqln2-based murine models of ALS Whiteley, Alexandra M.; Prado, Miguel A.; de Poot, Stefanie A.H. ...
Journal of biological chemistry/The Journal of biological chemistry,
01/2021, Letnik:
296
Journal Article
Recenzirano
Odprti dostop
Familial neurodegenerative diseases commonly involve mutations that result in either aberrant proteins or dysfunctional components of the proteolytic machinery that act on aberrant proteins. UBQLN2 ...is a ubiquitin receptor of the UBL/UBA family that binds the proteasome through its ubiquitin-like domain and is thought to deliver ubiquitinated proteins to proteasomes for degradation. UBQLN2 mutations result in familial amyotrophic lateral sclerosis (ALS)/frontotemporal dementia in humans through an unknown mechanism. Quantitative multiplexed proteomics was used to provide for the first time an unbiased and global analysis of the role of Ubqln2 in controlling the composition of the proteome. We studied several murine models of Ubqln2-linked ALS and also generated Ubqln2 null mutant mice. We identified impacts of Ubqln2 on diverse physiological pathways, most notably serotonergic signaling. Interestingly, we observed an upregulation of proteasome subunits, suggesting a compensatory response to diminished proteasome output. Among the specific proteins whose abundance is linked to UBQLN2 function, the strongest hits were the ubiquitin ligase TRIM32 and two retroelement-derived proteins, PEG10 and CXX1B. Cycloheximide chase studies using induced human neurons and HEK293 cells suggested that PEG10 and TRIM32 are direct clients. Although UBQLN2 directs the degradation of multiple proteins via the proteasome, it surprisingly conferred strong protection from degradation on the Gag-like protein CXX1B, which is expressed from the same family of retroelement genes as PEG10. In summary, this study charts the proteomic landscape of ALS-related Ubqln2 mutants and identifies candidate client proteins that are altered in vivo in disease models and whose degradation is promoted by UBQLN2.
The finding that deletion or mutation of core circadian clock genes in both mice and flies induce unexpected alterations in sleep amount, sleep architecture and the recovery response to sleep ...deprivation, has led to new insights into functions of the circadian system that extend beyond its role as a regulator of the timing of the sleep-wake cycle. A key transcription factor in the transcriptional/translational feedback loop of mammalian circadian genes is BMAL1/Mop3, a heterodimeric partner to CLOCK. It was previously shown that mice deficient in the BMAL1/Mop3 gene become immediately arrhythmic in constant darkness and have reduced locomotor activity levels under entrained and constant conditions. In this study, we tested the hypothesis that the mammalian BMAL1/Mop3 gene would have regulatory effects on sleep-wake patterns.
In mice with targeted deletion of the BMAL1/Mop3 gene, EEG/EMG sleep-wake patterns were recorded under entrained and free-running conditions as well as following acute (6-hrs) sleep deprivation.
Mice homozygous for the BMAL1/Mop3 deletion showed an attenuated rhythm of sleep and wakefulness distribution across the 24-hr period. In addition, these mice showed increases in total sleep time, sleep fragmentation and EEG delta power under baseline conditions, and an attenuated compensatory response to acute sleep deprivation.
These new data strengthen the hypothesis that molecular components of the circadian system play a central role in the generation of sleep and wakefulness beyond just the timing of these behavioral vigilance states.
Antisense oligonucleotide (ASO) therapeutics are being investigated for a broad range of neurological diseases. While ASOs have been effective in the clinic, improving productive ASO internalization ...into target cells remains a key area of focus in the field. Here, we investigated how the delivery of ASO-loaded lipid nanoparticles (LNPs) affects ASO activity, subcellular trafficking, and distribution in the brain. We show that ASO-LNPs increase ASO activity up to 100-fold in cultured primary brain cells as compared to non-encapsulated ASO. However, in contrast to the widespread ASO uptake and activity observed following free ASO delivery in vivo, LNP-delivered ASOs did not downregulate mRNA levels throughout the brain after intracerebroventricular injection. This lack of activity was likely due to ASO accumulation in cells lining the ventricles and blood vessels. Furthermore, we reveal a formulation-dependent activation of the immune system post dosing, suggesting that LNP encapsulation cannot mask cellular ASO backbone-mediated toxicities. Together, these data provide insights into how LNP encapsulation affects ASO distribution as well as activity in the brain, and a foundation that enables future optimization of brain-targeting ASO-LNPs.
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Here, Byrnes and colleagues examine how lipid nanoparticle (LNP) encapsulation affects antisense oligonucleotide (ASO) delivery to the brain. Compared with free ASO uptake, LNP delivery differentially regulated ASO distribution, activity, and immune cell function. Thus, this study reveals remaining challenges and opportunities for treatment of neurodegenerative disorders using ASO-LNPs.
Mutations in the GBA1 gene encoding glucocerebrosidase (GCase) are linked to Gaucher (GD) and Parkinson's Disease (PD). Since some GD and PD patients develop ocular phenotypes, we determined whether ...ocular phenotypes might result from impaired GCase activity and the corresponding accumulation of glucosylceramide (GluCer) and glucosylsphingosine (GluSph) in the Gba1
knock-in (Gba KI/KI; "KI") mouse. Gba KI mice developed age-dependent pupil dilation deficits to an anti-muscarinic agent; histologically, the iris covered the anterior part of the lens with adhesions between the iris and the anterior surface of the lens (posterior synechia). This may prevent pupil dilation in general, beyond an un-responsiveness of the iris to anti-muscarinics. Gba KI mice displayed atrophy and pigment dispersion of the iris, and occlusion of the iridocorneal angle by pigment-laden cells, reminiscent of secondary open angle glaucoma. Gba KI mice showed progressive thinning of the retina consistent with retinal degeneration. GluSph levels were increased in the anterior and posterior segments of the eye, suggesting that accumulation of lipids in the eye may contribute to degeneration in this compartment. We conclude that the Gba KI model provides robust and reproducible eye phenotypes which may be used to test for efficacy and establish biomarkers for GBA1-related therapies.
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