Biology subjects

Du, A.

Publications and source records attributed to Du, A..

22 records · Page 2Linked to original sources

bioRxiv2021

Thermal laser ablation with tunable lesion size reveals multiple origins of seizure-like convulsions in Caenorhabditis elegans

Laser microsurgery has long been an important means of assessing the functions of specific cells and tissues. Most laser ablation systems use short, highly focused laser pulses to create plasma-mediated lesions with dimensions on the order of the wavelength of light. While the small size of the lesion enables ablation with high spatial resolution, it also makes it difficult to ablate larger structures. We developed an infrared laser ablation system capable of thermally lesioning tissues with spot sizes tunable by the duration and amplitude of laser pulses. We used our laser system in the roundworm C. elegans to kill single neurons and to sever the dorsal and ventral nerve cords, structures that are difficult to lesion using a plasma-based ablation system. We used these ablations to investigate the source of convulsions in a gain-of-function mutant for the acetylcholine receptor ACR-2. Severing the ventral nerve cord caused convulsions to occur independently anterior and posterior to the lesion, suggesting that convulsions can arise independently from distinct subsets of the motor circuit.

neuroscience↗

bioRxiv2019

Fully Human Monoclonal Antibodies Effectively Neutralizing Botulinum Neurotoxin Serotype B

Botulinum neurotoxin (BoNT) is the most potent natural toxin known. Of the seven BoNT serotypes (A to G), types A, B, E, and F cause human botulism. Treatment of human botulism requires the development of effective toxin-neutralizing antibodies without side effects such as serum sickness and anaphylaxis. In this study, we generated fully human monoclonal antibodies (HuMAbs) against serotype B BoNT (BoNT/B1) using a murine-human chimera fusion partner cell line named SPYMEG. Of these HuMAbs, M2, which specifically binds to the light chain of BoNT/B1, showed neutralization activity in a mouse bioassay (approximately [≥] 100 i.p. LD50/mg of antibody), and M4, which binds to the C-terminal of heavy chain, showed partial protection. The combination of M2 and M4 was able to completely neutralize BoNT/B1 with a potency greater than 10,000 i.p. LD50/mg of antibodies, and was effective both prophylactically and therapeutically in the mouse model of botulism. Moreover, this combination showed broad neutralization activity against three type B subtypes, namely BoNT/B1, BoNT/B2, and BoNT/B6. These data demonstrate that the combination of M2 and M4 is promising in terms of a foundation for new human therapeutics for BoNT/B intoxication. IMPORTANCEBotulinum neurotoxins (BoNTs) produced by Clostridium botulinum and related species cause human botulism. Immunotherapy is the most effective treatment for botulism and equine immune serum formulations are used in cases of human botulism. However, these antisera may cause serum sickness or anaphylaxis. Additionally, the production of immune sera involves complicated and time-consuming manufacturing processes and quality management. Therefore, the development of safe, effective, and higher productive antibodies is required. Here we generated fully human monoclonal antibodies against serotype B BoNT (BoNT/B). We found that the combination of these antibodies (M2+M4) had potent and broad neutralization activity against BoNT/B, and showed therapeutic and preventive effects against botulism in mouse models. These data indicate that M2+M4 are promising candidates for the development of human therapeutics and prophylactics for BoNT/B intoxication.

microbiology↗

bioRxiv2019

Recombinant HcGAPDH Protein Expressed on Probiotic Bacillus subtilis Spores Protects Sheep from Haemonchus contortus Infection by Inducing both Humoral and Cell-mediated Responses

Probiotic Bacillales have been shown effective in controlling pathogens. In particular, live probiotic bacteria are thought to improve the composition of gastrointestinal microbiota, and to reduce pathogen colonization. However, how probiotics regulate immune responses and protect the host from parasitic infection remains largely unknown. In this study, we investigated whether Bacillales can be used against Haemonchus contortus, a parasitic nematode that infects small ruminants in sheep and goats worldwide. Using 16S ribosomal RNA sequencing, we found that Bacillales was highly depleted in the abomasal microbiota of sheep infected with H. contortus. We constructed a recombinant Bacillus subtilis strain (rBSCotB-HcG) that express glyceraldehyde-3-phosphate dehydrogenase of H. contortus (HcGAPDH) on its spore surface. However, mice orally administrated with the rBSCotB-HcG strain showed strong Th1-dominated immune responses; and sheep administrated per os with rBSCotB-HcG showed increased proliferation of peripheral blood mononuclear cells, elevated anti-HcGAPDH IgG levels in sera, and higher anti-HcGAPDH sIgA levels in intestinal mucus. In addition, treatment of H. contortus infected sheep with rBSCotB-HcG (Hc+rBSCotB-HcG) promoted the abundance of probiotic species in the abomasal microbiota; it also improved the average weight gain of the sheep by 27.7%. These Hc+rBSCotB-HcG sheep have reduced number of eggs per gram of feces (by 84.1%) and worm burdens (by 71.5%), with alleviated abomasal damage by H. contortus. Collectively, our data demonstrate the protective roles of CotB-HcGAPDH-expressing B. subtilis spores against H. contortus infection, suggesting a potential value of using this probiotic-based strategy in controlling parasitic nematodes of socioeconomic importance. ImportanceSequencing of the infected sheep s stomach flora revealed potential probiotics that could control H. contortus infection, and further genetically engineered recombinant probiotic spores expressing parasite protein, and validated their good immunogenicity in a mouse model. In the sheep infection model, the recombinant probiotics have proven to be effective against parasite infections.

microbiology↗

bioRxiv2018

PARylation modulates stress granule assembly, phase separation, and neurotoxicity of ALS-related RNA-binding proteins

Mutations in RNA-binding proteins localized in ribonucleoprotein (RNP) granules, such as hnRNP A1 and TDP-43, promote aberrant protein aggregations, which are pathological hallmarks in neurodegenerative diseases including amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Protein posttranslational modifications (PTMs) are known to regulate RNP granules. In this study, we investigate the function of PARylation, an important PTM involved in DNA damage repair and cell death, in RNP-related neurodegeneration. We reveal that PARylation levels are a major regulator of the dynamic assembly-disassembly of RNP granules, and the disease-related RNPs such as hnRNP A1 and TDP-43 can both be PARylated and bind to PARylated proteins. We further identify the PARylation site of hnRNP A1 at K298, which controls the cytoplasmic translocation of hnRNP A1 in response to stress, as well as the PAR-binding motif (PBM) of hnRNP A1, which is required for the delivery and association of hnRNP A1 to stress granules. Moreover, we show that PAR not only dramatically enhances the liquid-liquid phase separation of hnRNP A1, but also promotes the co-phase separation of hnRNP A1 and TDP-43 in vitro and their interaction in vivo. Finally, we establish that both genetic and pharmacological inhibition of PARP mitigates hnRNP A1 and TDP-43-mediated neurotoxicity in cell and Drosophila models of ALS. Together, our findings indicate a novel and crucial role of PARylation in regulating the assembly and the dynamics of RNP granules, and dysregulation of PARylation may contribute to ALS disease pathogenesis.

neuroscience↗