Mutation of Tar DNA‐binding protein 43 (TDP‐43) is linked to amyotrophic lateral sclerosis. Although astrocytes have important roles in neuron function and survival, their potential contribution to ...TDP‐43 pathogenesis is unclear. Here, we created novel lines of transgenic rats that express a mutant form of human TDP‐43 (M337V substitution) restricted to astrocytes. Selective expression of mutant TDP‐43 in astrocytes caused a progressive loss of motor neurons and the denervation atrophy of skeletal muscles, resulting in progressive paralysis. The spinal cord of transgenic rats also exhibited a progressive depletion of the astroglial glutamate transporters GLT‐1 and GLAST. Astrocytic expression of mutant TDP‐43 led to activation of astrocytes and microglia, with an induction of the neurotoxic factor Lcn2 in reactive astrocytes that was independent of TDP‐43 expression. These results indicate that mutant TDP‐43 in astrocytes is sufficient to cause non‐cell‐autonomous death of motor neurons. This motor neuron death likely involves deficiency in neuroprotective genes and induction of neurotoxic genes in astrocytes.
The debated role of astrocytes in amyotrophic lateral sclerosis (ALS) gains additional support from neurodegenerative phenotypes caused by astrocyte‐restricted expression of mutant TDP‐43 in transgenic rats.
Glial reaction is a common feature of neurodegenerative diseases. Recent studies have suggested that reactive astrocytes gain neurotoxic properties, but exactly how reactive astrocytes contribute to ...neurotoxicity remains to be determined. Here, we identify lipocalin 2 (lcn2) as an inducible factor that is secreted by reactive astrocytes and that is selectively toxic to neurons. We show that lcn2 is induced in reactive astrocytes in transgenic rats with neuronal expression of mutant human TAR DNA-binding protein 43 (TDP-43) or RNA-binding protein fused in sarcoma (FUS). Therefore, lcn2 is induced in activated astrocytes in response to neurodegeneration, but its induction is independent of TDP-43 or FUS expression in astrocytes. We found that synthetic lcn2 is cytotoxic to primary neurons in a dose-dependent manner, but is innocuous to astrocytes, microglia, and oligodendrocytes. Lcn2 toxicity is increased in neurons that express a disease gene, such as mutant FUS or TDP-43. Conditioned medium from rat brain slice cultures with neuronal expression of mutant TDP-43 contains abundant lcn2 and is toxic to primary neurons as well as neurons in cultured brain slice from WT rats. Partial depletion of lcn2 by immunoprecipitation reduced conditioned medium-mediated neurotoxicity. Our data indicate that reactive astrocytes secrete lcn2, which is a potent neurotoxic mediator.
Pathogenic mutation of ubiquilin 2 (UBQLN2) causes neurodegeneration in amyotrophic lateral sclerosis and frontotemporal lobar degeneration. How UBQLN2 mutations cause the diseases is not clear. ...While over‐expression of UBQLN2 with pathogenic mutation causes neuron death in rodent models, deletion of the Ubqln2 in rats has no effect on neuronal function. Previous findings in animal models suggest that UBQLN2 mutations cause the diseases mainly through a gain rather than a loss of functions. To examine whether the toxic gain in UBQLN2 mutation is related to the enhancement of UBQLN2 functions, we created new transgenic rats over‐expressing wild‐type human UBQLN2. Considering that human UBQLN2 may not function properly in the rat genome, we also created transgenic rats over‐expressing rat's own Ubqln2. When over‐expressed in rats, both human and rat wild‐type Ubqln2 caused neuronal death and spatial learning deficits, the pathologies that were indistinguishable from those observed in mutant UBQLN2 transgenic rats. Over‐expressed wild‐type UBQLN2 formed protein inclusions attracting the autophagy substrate sequestosome‐1 and the proteasome component 26S proteasome regulatory subunit 7. These findings suggest that excess UBQLN2 is toxic rather than protective to neurons and that the enhancement of UBQLN2 functions is involved in UBQLN2 pathogenesis.
Pathogenic mutation in ubiquilin 2 (UBQLN2) causes neurodegeneration in ALS and FTLD. Studies in rodent models suggest a gain of toxic function in mutant UBQLN2. We created new transgenic rats as a relevant model and examined whether enhancing wild‐type UBQLN2 expression is implicated in the pathogenesis of mutant UBQLN2. We observed that over‐expression of human or rat wild‐type Ubqln2 caused protein aggregation and neuronal death in transgenic rats. Our findings suggest that excess UBQLN2 is toxic rather than protective to neurons and that uncontrolled enhancement of UBQLN2 function is involved in UBQLN2 pathogenesis.
Read the Editorial Highlight for this article on page 159.
Pathogenic mutation in ubiquilin 2 (UBQLN2) causes neurodegeneration in ALS and FTLD. Studies in rodent models suggest a gain of toxic function in mutant UBQLN2. We created new transgenic rats as a relevant model and examined whether enhancing wild‐type UBQLN2 expression is implicated in the pathogenesis of mutant UBQLN2. We observed that over‐expression of human or rat wild‐type Ubqln2 caused protein aggregation and neuronal death in transgenic rats. Our findings suggest that excess UBQLN2 is toxic rather than protective to neurons and that uncontrolled enhancement of UBQLN2 function is involved in UBQLN2 pathogenesis.
Read the Editorial Highlight for this article on page 159.
A dominant mutation in hnRNPA1 causes amyotrophic lateral sclerosis (ALS), but it is not known whether this mutation leads to motor neuron death through increased or decreased function. To elucidate ...the relationship between pathogenic hnRNPA1 mutation and its native function, we created novel transgenic rats that overexpressed wildtype rat hnRNPA1 exclusively in motor neurons. This targeted expression of wildtype hnRNPA1 caused severe motor neuron loss and subsequent denervation muscle atrophy in transgenic rats that recapitulated the characteristics of ALS. These findings demonstrate that the augmentation of hnRNPA1 expression suffices to trigger motor neuron degeneration and the manifestation of ALS-like phenotypes. It is reasonable to infer that an amplification of an as-yet undetermined hnRNPA1 function plays a pivotal role in the pathogenesis of familial ALS caused by pathogenic hnRNPA1 mutation.
An experiment was conducted to investigate the effect of dietary supplementation of xylo-oligosaccharides（XOS） on growth performance, meat quality, immune functions, duodenal morphology and ...intestinal microbial populations of broilers fed a conventional corn-soybean meal basal diet. A total of 450 1-day-old commercial Arbor Acres male broiler chicks were randomly allocated by bodyweight to 1 of 5 treatments with 6 replicate cages（15 broilers per cage） for each of 5 treatments in a completely randomized design. Chicks were fed the basal corn-soybean meal diets supplemented with 0, 25, 50, 75, or 100 mg of XOS kg–1 of diet, respectively, for an experimental duration of 42 days. The results showed that supplementation of XOS affected feed conversion rate（feed/gain, F/G） during days 22–42 and 1–42（P〈0.03）, drip loss in thigh muscle（P=0.02）, and duodenal crypt depth（P=0.005） on day 42, but had no effect（P〉0.05） on all other measured indices. The chicks fed the diet supplemented with 100 mg of XOS kg–1 had the lowest（P〈0.05） F/G and drip loss in thigh muscle. The drip loss in thigh muscle decreased linearly（P=0.003） as the supplemented XOS increased. Duodenal crypt depth decreased（P〈0.05） at the supplemental level of 75 mg of XOS kg–1. The results indicate that dietary supplementations of 75 and 100 mg of XOS kg–1 are beneficial to broilers fed a conventional corn-soybean meal diet.
Mutation of profilin 1 (PFN1) can cause amyotrophic lateral sclerosis (ALS). To assess how PFN1 mutation causes the disease, we created transgenic rats with human genomic DNA that harbors both the ...coding and the regulatory sequences of the human PFN1 gene. Selected transgenic lines expressed human PFN1 with or without the pathogenic mutation C71G at a moderate and a comparable level and in the similar pattern of spatial and temporal expression to rat endogenous PFN1. The artificial effects of arbitrary transgene expression commonly observed in cDNA transgenic animals were minimized in PFN1 transgenic rats. Expression of the mutant, but not the wild type, human PFN1 in rats recapitulated the cardinal features of ALS including the progressive loss of motor neurons and the subsequent denervation atrophy of skeletal muscles. Detergent‐insoluble PFN1 inclusions were detected as the first pathology in otherwise asymptomatic transgenic rats expressing mutant human PFN1. The findings suggest that protein aggregation is involved in the neurodegeneration of ALS associated with PFN1 mutation. The resulting rat model is useful to mechanistic study on the ALS.
Pathogenic mutation of PFN1, an actin‐binding protein, causes motor neuron degeneration in amyotrophic lateral sclerosis. Transgenic rats expressing a mutant, but not the wild type, PFN1 recapitulated the cardinal features of the disease including late‐onset motor neuron degeneration and denervation atrophy. Prior to neurodegeneration in the transgenic rats, protein aggregation was detected as the first pathology. Mutant PFN1 aggressively formed detergent‐insoluble inclusions in affected motor neurons as detected by both biochemical analysis and pathological assays. The data suggest protein aggregation as an active player in the disease pathogenesis.
The present study aimed to investigate the ability of hesperidin to suppress the migration and invasion of A549 cells, and to investigate the role of the SDF-1/CXCR-4 cascade in this suppression.
We ...performed a Transwell migration assay to measure the migratory capability of A549 cells treated with 0.5% DMSO, SDF-1α, AMD3100 or hesperidin. The SDF-1 level in the culture medium was determined by an enzyme-linked immunosorbent assay (ELISA) to detect whether different concentrations of hesperidin affected SDF-1 secretion. A wound-healing assay was performed to determine the effects of different concentrations of hesperidin on the migration inhibition of A549, H460 and H1975 cells. Additionally, the effect of various hesperidin concentrations on the rate of A549 cell invasion and migration was examined with and without Matrigel in Transwell assays, respectively. Western blot analysis was used to evaluate the protein levels of CXCR-4, MMP-9, CK-19, Vimentin, p65, p-p65, p-IκB, IκB, p-Akt and Akt. RT-qPCR was used to detect the mRNA levels of CXCR-4, MMP-9, CK-19, Vimentin, p65, IκB, SDF-1 and Akt.
The Transwell migration assay indicated that SDF-1α promoted A549 cell migration, while AMD3100 and hesperidin significantly inhibited the migratory capability. The wound-healing assay demonstrated that hesperidin treatment significantly reduced the rate of wound closure compared with the control group in a dose-dependent manner. Similarly, the migration and invasive abilities of A549 cells, H460 and H1975 cells treated with hesperidin were significantly decreased compared with the control group. The ELISA data suggested that hesperidin attenuated the secretion of SDF-1 from A549 cells in a dose-dependent manner. Furthermore, western blot analysis indicated that SDF-1α treatment significantly increased the levels of CXCR-4, p-p65, p-IκB and p-Akt in A549 cells. In contrast, AMD3100 or hesperidin reversed the effect induced by SDF-1α through decreasing the expression of CXCR-4. Subsequent RT-qPCR and western blot analyses also confirmed that hesperidin had a significant effect on the expression of EMT-related proteins, including MMP-9, CK-19 and Vimentin, in A549 cells.
In summary, we demonstrated that hesperidin inhibited the migratory and invasive capabilities of A549 human non-small cell lung cancer cells by the mediation of the SDF-1/CXCR-4 signaling cascade, thus providing the foundation for the development of hesperidin as a safer and more effective anticancer drug for non-small cell lung cancer.
Effective photosensitizers are of particular importance for the widespread clinical utilization of phototherapy. However, conventional photosensitizers are usually plagued by short-wavelength ...absorption, inadequate photostability, low reactive oxygen species (ROS) quantum yields, and aggregation-caused ROS quenching. Here, we report a near-infrared (NIR)-supramolecular photosensitizer (RuDA) via self-assembly of an organometallic Ru(II)-arene complex in aqueous solution. RuDA can generate singlet oxygen (
O
) only in aggregate state, showing distinct aggregation-induced
O
generation behavior due to the greatly increased singlet-triplet intersystem crossing process. Upon 808 nm laser irradiation, RuDA with excellent photostability displays efficient
O
and heat generation in a
O
quantum yield of 16.4% (FDA-approved indocyanine green: Φ
= 0.2%) together with high photothermal conversion efficiency of 24.2% (commercial gold nanorods: 21.0%, gold nanoshells: 13.0%). In addition, RuDA-NPs with good biocompatibility can be preferably accumulated at tumor sites, inducing significant tumor regression with a 95.2% tumor volume reduction in vivo during photodynamic therapy. This aggregation enhanced photodynamic therapy provides a strategy for the design of photosensitizers with promising photophysical and photochemical characteristics.
Amyotrophic lateral sclerosis (ALS) is characterized by progressive motor neuron degeneration, which ultimately leads to paralysis and death. Mutation of TAR DNA binding protein 43 (TDP-43) has been ...linked to the development of an inherited form of ALS. Existing TDP-43 transgenic animals develop a limited loss of motor neurons and therefore do not faithfully reproduce the core phenotype of ALS. Here, we report the creation of multiple lines of transgenic rats in which expression of ALS-associated mutant human TDP-43 is restricted to either motor neurons or other types of neurons and skeletal muscle and can be switched on and off. All of these rats developed progressive paralysis reminiscent of ALS when the transgene was switched on. Rats expressing mutant TDP-43 in motor neurons alone lost more spinal motor neurons than rats expressing the disease gene in varying neurons and muscle cells, although these rats all developed remarkable denervation atrophy of skeletal muscles. Intriguingly, progression of the disease was halted after transgene expression was switched off; in rats with limited loss of motor neurons, we observed a dramatic recovery of motor function, but in rats with profound loss of motor neurons, we only observed a moderate recovery of motor function. Our finding suggests that mutant TDP-43 in motor neurons is sufficient to promote the onset and progression of ALS and that motor neuron degeneration is partially reversible, at least in mutant TDP-43 transgenic rats.
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