Classical swine fever (CSF), caused by classical swine fever virus (CSFV), is an important and highly infectious pig disease worldwide. Kinesin-1, a molecular motor responsible for transporting cargo ...along the microtubule, has been demonstrated to be involved in the infections of diverse viruses. However, the role of kinesin-1 in the CSFV life cycle remains unknown. Here, we first found that Kif5B played a positive role in CSFV entry by knockdown or overexpression of Kif5B. Subsequently, we showed that Kif5B was associated with the endosomal and lysosomal trafficking of CSFV in the early stage of CSFV infection, which was reflected by the colocalization of Kif5B and Rab7, Rab11, or Lamp1. Interestingly, trichostatin A (TSA) treatment promoted CSFV proliferation, suggesting that microtubule acetylation facilitated CSFV endocytosis. The results of chemical inhibitors and RNA interference showed that Rac1 and Cdc42 induced microtubule acetylation after CSFV infection. Furthermore, confocal microscopy revealed that cooperation between Kif5B and dynein help CSFV particles move in both directions along microtubules. Collectively, our study shed light on the role of kinesin motor Kif5B in CSFV endocytic trafficking, indicating the dynein/kinesin-mediated bidirectional CSFV movement. The elucidation of this study provides the foundation for developing CSFV antiviral drugs.
The minus end-directed cytoplasmic dynein and the plus end-directed kinesin-1 are the molecular motors that transport cargo on microtubules in intracellular trafficking, which plays a notable role in the life cycles of diverse viruses. Our previous studies have reported that the CSFV entry host cell is dependent on the microtubule-based motor dynein. However, little is known about the involvement of kinesin-1 in CSFV infection. Here, we revealed the critical role of kinesin-1 that regulated the viral endocytosis along acetylated microtubules induced by Cdc42 and Rac1 after CSFV entry. Mechanistically, once CSFV transported by dynein met an obstacle, it recruited kinesin-1 to move in reverse to the anchor position. This study extends the theoretical basis of intracellular transport of CSFV and provides a potential target for the control and treatment of CSFV infection.
Vimentin (VIM), an indispensable protein, is responsible for the formation of intermediate filament structures within cells and plays a crucial role in viral infections. However, the precise role of ...VIM in classical swine fever virus (CSFV) infection remains unclear. Herein, we systematically investigated the function of VIM in CSFV replication. We demonstrated that both knockdown and overexpression of VIM affected CSFV replication. Furthermore, we observed by confocal microscopy the rearrangement of cellular VIM into a cage-like structure during CSFV infection. Three-dimensional (3D) imaging indicated that the cage-like structures were localized in the endoplasmic reticulum (ER) and ringed around the double-stranded RNA (dsRNA), thereby suggesting that VIM was associated with the formation of the viral replication complex (VRC). Mechanistically, phosphorylation of VIM at serine 72 (Ser72), regulated by the RhoA/ROCK signaling pathway, induced VIM rearrangement upon CSFV infection. Confocal microscopy and coimmunoprecipitation assays revealed that VIM colocalized and interacted with CSFV NS5A. Structurally, it was determined that amino acids 96 to 407 of VIM and amino acids 251 to 416 of NS5A were the respective important domains for this interaction. Importantly, both VIM knockdown and disruption of VIM rearrangement inhibited the localization of NS5A in the ER, implying that VIM rearrangement recruited NS5A to the ER for VRC formation. Collectively, our results suggest that VIM recruits NS5A to form a stable VRC that is protected by the cage-like structure formed by VIM rearrangement, ultimately leading to enhanced virus replication. These findings highlight the critical role of VIM in the formation and stabilization of VRC, which provides alternative strategies for the development of antiviral drugs.
Classical swine fever (CSF), caused by classical swine fever virus (CSFV), is a highly infectious disease that poses a significant threat to the global pig industry. Therefore, gaining insights into the virus and its interaction with host cells is crucial for developing effective antiviral measures and controlling the spread of CSF. Previous studies have shown that CSFV infection induces rearrangement of the endoplasmic reticulum, leading to the formation of small vesicular organelles containing nonstructural protein and double-stranded RNA of CSFV, as well as some host factors. These organelles then assemble into viral replication complexes (VRCs). In this study, we have discovered that VIM recruited CSFV NS5A to form a stable VRC that was protected by a cage-like structure formed by rearranged VIM. This enhanced viral replication. Our findings not only shed light on the molecular mechanism of CSFV replication but also offer new insights into the development of antiviral strategies for controlling CSFV.
The cytoskeleton, as a ubiquitous structure in the cells, plays an important role in the processes of virus entry, replication, and survival. However, the action mechanism of the cytoskeleton in the ...invasion of pestivirus into host cells remains unclear. In this study, we systematically dissected the key roles of the main cytoskeleton components, namely microfilaments and microtubules, in the endocytosis of the porcine pestivirus classical swine fever virus (CSFV). We observed the dynamic changes of actin filaments in CSFV entry. Confocal microscopy showed that CSFV invasion induced the dissolution and aggregation of stress fibers, resulting in the formation of lamellipodia and filopodia. Chemical inhibitors and RNA interference were used to find that the dynamic changes of actin were caused by an EGFR-PI3K/MAPK-RhoA/Rac1/Cdc42-cofilin signaling pathway, which regulates the microfilaments to help CSFV entry. Furthermore, colocalization of the microfilaments with clathrin and Rab5 (early endosome), as well as that of microtubules with Rab7 (late endosome) and Lamp1 (lysosome) revealed that microfilaments were activated and rearranged to help CSFV trafficking to the early endosome after endocytosis. Subsequently, recruitment of microtubules by CSFV also assisted membrane fusion of the virions from the late endosome to the lysosome with the help of a molecular motor, dynein. Unexpectedly, vimentin, which is an intermediate filament, had no effect on CSFV entry. Taken together, our findings comprehensively revealed the molecular mechanisms of cytoskeletal components that regulated CSFV endocytosis and facilitated further understanding of pestivirus entry, which would be conducive to exploration of antiviral molecules to control classical swine fever. IMPORTANCE Endocytosis, an essential biological process mediating cellular internalization events, is often exploited by pathogens for their entry into target cells. Previously, we reported different mechanisms of CSFV endocytosis into the porcine epithelial cells (PK-15) and macrophages (3D4/21); however, the details of microfilaments/microtubules mediated virus migration within the host cells remained to be elucidated. In this study, we found that CSFV infection induced rearrangement of actin filaments regulated by cofilin through an EGFR-PI3K/MAPK-RhoA/Rac1/Cdc42 pathway. Furthermore, we found that CSFV particles were trafficked along actin filaments in early and late endosomes, and through microtubules in lysosomes after entry. Here, we provide for the first time a comprehensive description of the cytoskeleton that facilitates the entry and the intracellular transport of a highly pathogenic swine virus. Results from this study will greatly contribute to the understanding of virus-induced early and complex changes in host cells that are important in CSFV pathogenesis.
Straw mulching allows for effective water storage in dryland wheat production.Finding a suitable straw mulching model that facilitates wheat growth was the objective of this study.A 2-year field ...experiment was conducted to investigate the effects of two straw mulching patterns (FM,full coverage within all the rows;HM,half coverage within alternate rows) and two mulching rates (4.5 and 9.0 t ha-1) on soil moisture,soil temperature,grain yield,and water use efficiency (WUE) of winter wheat in northern China,with no mulching (M0) as the control.Results showed that mulching increased the soil water storage in all growth stages under high mulching rates,with a stronger effect in later growth stages.Water storage under the HM model was greater in later stages than under the FM model.Soil water content of HM groups was higher than that of FM groups,especially in surface soil layers.Evapotranspiration decreased in mulched groups and was higher under high mulching rates.Aboveground biomass during each growth stage under the HM model was higher than that under M0 and FM models with the same mulched rate,leading to a relatively higher grain yield under the HM model.Mulching increased WUE,a trend that was more obvious under HM9.0 treatment.Warming effect of soil temperature under the HM pattern persisted longer than under the FM model with the same mulching rates.Accumulated soil temperature under mulched treatments increased,and the period of negative soil temperature decreased by 9-12 days under FM and by 10-20 days under HM.Thus,the HM pattern with 9.0 t ha-1 mulching rate is beneficial for both soil temperature and water content management and can contribute to high yields and high WUE for wheat production in China.
Cytoskeleton, as a ubiquitous structure in the cells, plays an important role in the process of virus entry, replication, and survival. However, the action mechanism of cytoskeleton in the invasion ...of Pestivirus into host cells remains unclear. In this study, we systematically dissected the key roles of the main cytoskeleton components, microfilaments and microtubules in the endocytosis of porcine Pestivirus, Classical swine fever virus (CSFV). We observed the dynamic changes of actin filaments in CSFV entry. Confocal microscopy showed that CSFV invasion induced the dissolution and aggregation of stress fibers, resulting in the formation of lamellipodia and filopodia. Chemical inhibitors and RNA interference were used to find that the dynamic changes of actin were caused by EGFR-PI3K/MAPK-RhoA/Rac1/Cdc42-cofilin signaling pathway, which regulates the microfilaments to help CSFV entry. Furthermore, co-localization of the microfilaments with clathrin and Rab5 (early endosome), as well as microtubules with Rab7 (late endosome) and Lamp1 (lysosome) revealed that microfilaments were activated and rearranged to help CSFV trafficking to early endosome after endocytosis. Subsequently, recruitment of microtubules by CSFV also assisted membrane fusion of the virions from late endosome to lysosome with the help of a molecular motor, dynein. Unexpectedly, vimentin, which is an intermediate filament, had no effect on CSFV entry. Taken together, our findings comprehensively revealed the molecular mechanisms of cytoskeletal components that regulated CSFV endocytosis and facilitated further understanding of Pestivirus entry, which would be conducive to explore antiviral molecules to control classical swine fever.
Endocytosis, an essential biological process mediating cellular internalization events, is often exploited by pathogens for their entry into target cells. Previously, we have reported different mechanisms of CSFV endocytosis into the porcine epithelial cells (PK-15) and macrophages (3D4/21); however, the details of microfilaments/microtubules mediated virus migration within the host cells remained to be elucidated. In this study, we found that CSFV infection induced rearrangement of actin filaments regulated by cofilin through EGFR-PI3K/MAPK-RhoA/Rac1/Cdc42 pathway. Furthermore, we found that CSFV particles were trafficked along actin filaments in early and late endosomes, and through microtubules in lysosomes after entry. Here, we provide for the first time a comprehensive description of the cytoskeleton that facilitates entry and intracellular transport of highly pathogenic swine virus. Results from this study will greatly contribute to the understanding of virus-induced early and complex changes in host cells that are important in CSFV pathogenesis.
Abstract
Background
Due to post-cleavage residence of the Cas9-sgRNA complex at its target, Cas9-induced DNA double-strand breaks (DSBs) have to be exposed to engage DSB repair pathways. Target ...interaction of Cas9-sgRNA determines its target binding affinity and modulates its post-cleavage target residence duration and exposure of Cas9-induced DSBs. This exposure, via different mechanisms, may initiate variable DNA damage responses, influencing DSB repair pathway choices and contributing to mutational heterogeneity in genome editing. However, this regulation of DSB repair pathway choices is poorly understood.
Results
In repair of Cas9-induced DSBs, repair pathway choices vary widely at different target sites and classical nonhomologous end joining (c-NHEJ) is not even engaged at some sites. In mouse embryonic stem cells, weakening the target interaction of Cas9-sgRNA promotes bias towards c-NHEJ and increases target dissociation and reduces target residence of Cas9-sgRNAs in vitro. As an important strategy for enhancing homology-directed repair, inactivation of c-NHEJ aggravates off-target activities of Cas9-sgRNA due to its weak interaction with off-target sites. By dislodging Cas9-sgRNA from its cleaved targets, DNA replication alters DSB end configurations and suppresses c-NHEJ in favor of other repair pathways, whereas transcription has little effect on c-NHEJ engagement. Dissociation of Cas9-sgRNA from its cleaved target by DNA replication may generate three-ended DSBs, resulting in palindromic fusion of sister chromatids, a potential source for CRISPR/Cas9-induced on-target chromosomal rearrangements.
Conclusions
Target residence of Cas9-sgRNA modulates DSB repair pathway choices likely through varying dissociation of Cas9-sgRNA from cleaved DNA, thus widening on-target and off-target mutational spectra in CRISPR/Cas9 genome editing.
Abstract Invasive brain glioma is the most lethal type of cancer and is highly infiltrating. This leads to an extremely poor prognosis and makes complete surgical removal of the tumor virtually ...impossible. Non-penetration of therapeutic drugs across the blood–brain barrier (BBB), brain cancer stem cells (CSCs), and brain cancer vasculogenic mimicry (VM) results in relapse after surgical and radio therapy. We developed a functional targeting chemotherapy for transporting drugs across the BBB, destroying VM channels, and eliminating CSCs and cancer cells in the brain. The studies were undertaken on brain glioma cells in vitro and in brain glioma-bearing rats. Using paclitaxel as the anticancer drug and artemether as the regulator of apoptosis and inhibitor of VM channels, a kind of functional targeting paclitaxel plus artemether liposomes was developed by modifying two new functional materials: a mannose-vitamin E derivative conjugate (MAN-TPGS1000 ) and a dequalinium-lipid derivative conjugate (DQA-PEG2000 -DSPE). The transport mechanism across the BBB was associated with receptor-mediated endocytosis by MAN-TPGS1000 conjugate via glucose transporters and adsorptive-mediated endocytosis by DQA-PEG2000 -DSPE conjugate via electric charge-based interactions. The efficacy was related to the destruction of VM channels by regulating VM indicators, as well as the induction of apoptosis in brain cancer cells and CSCs by activating apoptotic enzymes and pro-apoptotic proteins and inhibiting anti-apoptotic proteins. These data suggest that the chemotherapy using functional targeting paclitaxel plus artemether liposomes could provide a new strategy for treating invasive brain glioma.
Reactive oxygen species formed within the mammalian cell can produce 8-oxo-7,8-dihydroguanine (8-oxoG) in mRNA, which can cause base mispairing during gene expression. Here we found that ...administration of 8-oxoGTP in MTH1-knockdown cells results in increased 8-oxoG content in mRNA. Under this condition, an amber mutation of the reporter luciferase is suppressed. Using secondgeneration sequencing techniques, we found that U-to-G changes at preassigned sites of the luciferase transcript increased when 8-oxoGTP was supplied. In addition, an increased level of 8-oxoG content in RNA induced the accumulation of aggregable amyloid β peptides in cells expressing amyloid precursor protein. Our findings indicate that 8-oxoG accumulation in mRNA can alter protein synthesis in mammalian cells. Further work is required to assess the significance of these findings under normal physiological conditions.
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