Histone deacetylase 3 promotes innate antiviral immunity through deacetylation of TBK1

TANK-binding kinase 1 (TBK1), a core kinase of antiviral pathways, activates the production of interferons (IFNs). It has been reported that deacetylation activates TBK1; however, the precise mechanism still remains to be uncovered. We show here that during the early stage of viral infection, the acetylation of TBK1 was increased, and the acetylation of TBK1 at Lys241 enhanced the recruitment of IRF3 to TBK1. HDAC3 directly deacetylated TBK1 at Lys241 and Lys692, which resulted in the activation of TBK1. Deacetylation at Lys241 and Lys692 was critical for the kinase activity and dimerization of TBK1 respectively. Using knockout cell lines and transgenic mice, we confirmed that a HDAC3 null mutant exhibited enhanced susceptibility to viral challenge via impaired production of type I IFNs. Furthermore, activated TBK1 phosphorylated HDAC3, which promoted the deacetylation activity of HDAC3 and formed a feedback loop. In this study, we illustrated the roles the acetylated and deacetylated forms of TBK1 play in antiviral innate responses and clarified the post-translational modulations involved in the interaction between TBK1 and HDAC3.

Localization of AcMNPV NLA genes in Sf9 cells / 病毒学报

Nuclear actin which plays a key role in many nucleic processes has become a research hotspot. Baculovirus is the only reported pathogen using nuclear actin to replicate and proliferate. However, little is known about the mechanism of monomeric G-actin accumulation within nuclei of baculovirus-infected cells. It has been reported that AcMNPV ie-1, pe38, ac4, he65, ac102, and ac152 could be required for mediating nuclear localization of G-actin from transiently transfected results in TN-368 cells. In this paper, we found that IE1, AC152, PE38, AC102 localized in the whole cell and PE38, AC102 localized in the nuclear mainly, while both AC4 and HE65 localized in cytoplasm and could be mediated into the nucleus by AC102 and IE1 respectively for the first time. And ie-1 or pe38, ac4, he65 could mediate nuclear G-actin to accumulate partly, while these four genes were sufficient for recruiting G-actin accumulation within the nucleus when driven by promoter OpIE2. Determining the functions of each of these AcMNPV NLA gene products will advance our understanding of baculovirus biology and function of nuclear actin.

Cloning and functional research of Arp2/3-P40/ARPC1 subunit of Sf9 cells / 病毒学报

The baculovirus-induced actin polymerization is mainly associated with the virus nucleocapsid protein P78/83, which is homologous with WASP proteins that can activate Arp2/3 complex and induce the actin polymerization. In order to explore the role of Arp2/3 complex in the baculovirus replication, the P40 subunit of Arp2/3 complex from Sf9 (Spodoptera frugiperda 9) cell line was cloned and characterized. Immunofluorescent microscopy assay indicated that P40 was recruited to the inner-side of nuclear membrane during virus infection, which was in accordance with nuclear F-actin distribution in virus-infected cells as documented in our previous research, suggesting P40 could be used to track Arp2/3 complex subcellular distribution changes during virus infection. In addition, co-immunoprecipitation assay demonstrated that P40 interacted with P78/83 only in virus-infected cells, suggesting that actin polymerization induced by P78/83-Arp2/3 complex during baculovirus infection was regulated by some unidentified virus factors.

Effects of hFRNK on E-cadherin/beta-catenin in colon cancer cells in vitro / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To explore the effects of human FRNK gene on E-cadherin/beta-catenin complex in colon cancer cell line Colo320WT cells stimulated with extrinsic gastrinl7.</p><p><b>METHODS</b>AdEasy system was used to construct pAdhFRNK expressing human FRNK gene by recombination in E. coli. BJ5283. pCR3.1/GR plasmid expressing gastrin receptor CCK-2 was transfected into colon cancer cell line Colo320 cells by Lipofectamine 2000 and expressing stably CCK-2R clones were screened by G418 (500 pg/ml). The expression levels of gastrin receptor in Colo320 cells and the transfected Colo320WT cells were assayed by RT-PCR. Colo320WT cells were treated by 10(-8) mol/L gastrinl7 for 12 h; and after Colo320WT cells were infected by pAdhFRNK (MOI: 100) for 2 d the cells were treated by gastrin17 for 12 h again. The expression levels of E-cadherin and beta-catenin in TX-100 soluble fraction and TX-100 insoluble fraction of Colo320WT cells were assayed by co-immunoprecipation and Western blot. E-cadherin and beta-catenin's distribution in Colo320WT cells were detected by immunocytochemistry.</p><p><b>RESULTS</b>When 10(-8) mol/L gastrin17 stimulated Colo320WT cells for 12 h, the expression levels of E-cadherin and beta-catenin in TX-100-soluble fraction decreased apparently, while the expression levels of E-cadherin and beta-catenin in TX-100-insoluble fraction increased markedly. When pAdhFRNK infected Colo320WT cells for 2 d and 10(-8) mol/L gastrin17 treated the cells for 12 h, the expression levels of E-cadherin and beta-catenin in TX-100-soluble fraction increased apparently again, and the expression levels of E-cadherin and beta-catenin in TX-100-insolutble fraction decreased markedly. Immunocytochemistry showed that the distribution of E-cadherin and beta-catenin was translocated from plasma membrane into cytoplasm and nucleus in the cells stimulated with gastrinl7, and after the cells were infected with pAdhFRNK and stimulated by gastrinl7 again. beta-catenin was mainly observed in cytoplasm and little nuclear immunoreactivity.</p><p><b>CONCLUSION</b>An adenovirus vector pAdhFRNK can inhibit abnormal distribution of E-cadherin and beta-catenin in the gastrin17-stimulated cells. The mechanism is probably that hFRNK can disphosphorylate phosphorylated FAK and block FAK pathway.</p>

Construction of recombinant baculovirus Ac-CMV-hSox9 for gene therapy of intervertebral disc degeneration / 中华创伤杂志(英文版)

<p><b>OBJECTIVE</b>To construct the recombinant baculovirus Ac-cytomegalovirus (CMV)-hSox9 for gene therapy of intervertebral disc degeneration.</p><p><b>METHODS</b>Bac-to-Bac system was used for the construction of baculovirus Ac-CMV-hSox9. The cDNA of hSox9 was first cloned into a plasmid vector under the control of CMV promotor to generate the donor plasmid pFastBacDuljgreen fluorescene protein (GFP)-CMV (pFGC)-hSox9. The resultant plasmid was transformed into DH10Bac cells and then the transformation mixture was spread on Luria-Bertani (LB) agarose culture medium containing isopropyl-beta-D-thiogalactoside (IPTG), X-gal, gentamicin, kanamycin and tetracycline. The white colonies were selected and cultured for amplification, and the hSox9Bacmid DNA was extracted. After verification, recombinant baculovirus Ac-CMV-hSox9 was obtained through transfecting Sf 21 cells. The expression of hSox9 gene in the intervertebral disc cells in rabbits was determined by Western blotting and immunohistochemical staining.</p><p><b>RESULTS</b>Polymerase chain reaction (PCR) confirmed the presence of hSox9 gene in the recombinant baculovirus and the Sf 21 cells transfected by the baculovirus showed the expression of fluorescence protein. Western blotting and immunohistochemical staining analysis indicated that exogenous hSox9 gene was expressed in the disc cells.</p><p><b>CONCLUSIONS</b>The successful construction of the recombinant baculovirus Ac-CMV-hSox9 and the confirmation of the target gene expression provides a novel expression vector system for basic research and clinical treatment of intervertebral degenerative disc disease.</p>

Baculoviruses as Vectors in Mammalian Cells / 中国病毒学

The Baculoviridae are a large family of enveloped DNA viruses exclusively pathogenic to arthropods. Baculoviruses have been extensively used in insect cell-based recombinant protein expression system and as biological pesticides. They have been deomostrated to be safe to mammals, birds and fish. Recently, baculoviruses has been shown to transduce different mammalian cells in spite of the fact that they cannot replicate in mammalian cells (11, 73, 76). This has resulted in the development of baculoviruses as mammalian expression systems and even as vestors for gene therapy.

Baculovirus-mediated Expression of p35 Confers Resistance to Apoptosis in Human Embryo Kidney 293 cells / 中国病毒学

Baculovirus has many advantages as vectors for gene transfer. We demonstrated that recombinant baculovirus vectors expressing p35 (Ac-CMV-p35) and eGFP (Ac-CMV-GFP) could be transduced into human kidney 293 cells efficiently. The level of transgene expression was viral dose dependent and high-level expression of the target gene could be achieved under the heterogonous promoter. MTT assay suggested that both Ac-CMV-p35 and Ac-CMV-GFP did not have cytotoxic effect on human embryo kidney 293 cells. Cell growth curve showed the Ac-CMV-p35 and Ac- CMV-GFP transduced and non-transduced cells had similar proliferation rate, so baculovirus-mediated p35expression had no adverse effect on cell proliferation. In addition, baculovirus-mediated p35 gene expression protected human embryo kidney 293 cells against apoptosis induced by various apoptosis inducers such as Actinomycin D, UV or serum-free media. These results suggested that the baculovirus vector mediated p35 gene expression was functional and it could be widely used in molecular research and even gene therapy.