Huaiqiang Ju

Cofilin 1-Mediated Biphasic F-Actin Dynamics of Neuronal Cells Affect Herpes Simplex Virus 1 Infection and Replication

ABSTRACT Herpes simplex virus 1 (HSV-1) invades the nervous system and causes pathological changes. In this study, we defined the remodeling of F-actin and its possible mechanisms during HSV-1 infection of neuronal cells. HSV-1 infection enhanced the formation of F-actin-based structures in the early stage of infection, which was followed by a continuous decrease in F-actin during the later stages of infection. The disruption of F-actin dynamics by chemical inhibitors significantly reduced the efficiency of viral infection and intracellular HSV-1 replication. The active form of the actin-depolymerizing factor cofilin 1 was found to increase at an early stage of infection and then to continuously decrease in a manner that corresponded to the remodeling pattern of F-actin, suggesting that cofilin 1 may be involved in the biphasic F-actin dynamics induced by HSV-1 infection. Knockdown of cofilin 1 impaired HSV-1-induced F-actin assembly during early infection and inhibited viral entry; however, overexpression of cofilin 1 did not affect F-actin assembly or viral entry during early infection but decreased intracellular viral reproduction efficiently. Our results, for the first time, demonstrated the biphasic F-actin dynamics in HSV-1 neuronal infection and confirmed the association of F-actin with the changes in the expression and activity of cofilin 1. These results may provide insight into the mechanism by which HSV-1 productively infects neuronal cells and causes pathogenesis.

Pentagalloylglucose downregulates cofilin1 and inhibits HSV-1 infection

To investigate the anti-herpesvirus mechanism of pentagalloylglucose (PGG), we compared the proteomic changes between herpes simplex virus type 1 (HSV-1) infected MRC-5 cells with or without PGG-treatment, and between non-infected MRC-5 cells with or without PGG-treatment by 2-DE and MS-based analysis. Differentially expressed cellular proteins were mainly involved with actin cytoskeleton regulation. Significantly, PGG can down-regulate cofilin1, a key regulator of actin cytoskeleton dynamics. PGG can inhibit HSV-1-induced rearrangements of actin cytoskeleton which is important for infectivity. Furthermore, cofilin1 knockdown by siRNA also inhibited the HSV-1-induced actin-skeleton rearrangements. Both PGG-treatment and cofilin1 knockdown can reduce HSV-1 DNA, mRNA, protein synthesis and virus yields. Altogether, the results suggested that down-regulating cofilin1 plays a role in PGG inhibiting HSV-1 infection. PGG may be a promising anti-herpesvirus agent for drug development.

Autophagy is involved in anti-viral activity of pentagalloylglucose (PGG) against Herpes simplex virus type 1 infection in vitro

Pentagalloylglucose (PGG) is a natural polyphenolic compound with broad-spectrum anti-viral activity, however, the mechanisms underlying anti-viral activity remain undefined. In this study, we investigated the effects of PGG on anti-viral activity against Herpes simplex virus type 1 (HSV-1) associated with autophagy. We found that the PGG anti-HSV-1 activity was impaired significantly in MEF-atg7-/- cells (autophagy-defective cells) derived from an atg7-/- knockout mouse. Transmission electron microscopy revealed that PGG-induced autophagosomes engulfed HSV-1 virions. The mTOR signaling pathway, an essential pathway for the regulation of autophagy, was found to be suppressed following PGG treatment. Data presented in this report demonstrated for the first time that autophagy induced following PGG treatment contributed to its anti-HSV activity in vitro.

Proteomics analysis of autophagy-deficient Atg7−/− MEFs reveals a close relationship between F-actin and autophagy

Autophagy plays a crucial role in a wide array of physiological processes. To uncover the complex regulatory networks and mechanisms underlying basal autophagy, we performed a quantitative proteomics analysis of autophagy-deficient mouse embryonic fibroblast cells (MEFs) using iTRAQ labeling coupled with on-line 2D LC/MS/MS. We quantified a total of 1234 proteins and identified 114 proteins that were significantly altered (90% confidence interval), including 48 up-regulated proteins and 66 down-regulated proteins. We determined that F-actin was disassembled in autophagy-deficient Atg7(-/-) MEFs. Treatment of the WT MEFs with cytochalasin D (CD), which induces F-actin depolymerization, significantly induced autophagosome formation. However, treatment with cytochalasin D also increased the protein level of p62 under starvation conditions, suggesting that depolymerization of F-actin impaired autophagosome maturation and that the intact F-actin network is required for basal and starvation-induced autophagy. Our results demonstrate a close relationship between F-actin and autophagy and provide the basis for further investigation of their interactions.

Synthesis and in vitro anti-HSV-1 activity of a novel Hsp90 inhibitor BJ-B11

In this study, a novel Hsp90 inhibitor BJ-B11, was synthesized and evaluated for in vitro antiviral activity against several viruses. Possible anti-HSV-1 mechanisms were also investigated. BJ-B11 displayed no antiviral activity against coxsackievirus B(3) (CVB(3)), human respiratory syncytial virus (RSV) and influenza virus (H1N1), but exhibited potent anti-HSV-1 and HSV-2 activity with EC(50) values of 0.42±0.18 μM and 0.60±0.21 μM, respectively. Additionally, the inhibitory effects of BJ-B11 against HSV-1 were likely to be introduced at early stage of infection. Our results indicate that BJ-B11 with alternative mechanisms of action is potent as an anti-HSV clinical trial candidate.

BJ-B11, a novel Hsp90 inhibitor, induces apoptosis in human chronic myeloid leukemia K562 cells through the mitochondria-dependent pathway.

In the past few years heat shock protein 90 (Hsp90) inhibitors have been reported to possess significant antitumor activity. We investigated, for the first time, the antitumor activity of a novel Hsp90 inhibitor 2-(4-acetyloxycyclohexylamino)-4-(3, 6, 6-trimethyl-4-oxo-4, 5, 6, 7-tetrahydro-1H-indazol-1-yl)-benzamide (BJ-B11) and the molecular mechanism underlying the apoptosis it induces in human chronic myeloid leukemia K562 cells. The results revealed that BJ-B11 triggered growth inhibition in K562 cells and other malignant cell lines in vitro with only minor toxicity in a normal human cell line. BJ-B11 inhibited the proliferation of K562 cells in a concentration- and time-dependent manner, with IC(50) values of 1.1 ± 0.2 μM and 0.4 ± 0.1 μM after 48 and 72 h incubations respectively. This most likely results from cell cycle arrest at the G(0)/G(1) phase and the induction of apoptosis. In addition, BJ-B11 degraded the Hsp90 client proteins Bcr-Abl and Akt, induced activation of caspase-9 and caspase-3, and subsequent cleavage of PARP. The caspase signals may originate from mitochondrial dysfunction, which is supported by the finding of cytochrome c release. In addition, inactivation of the Akt signaling pathway may be involved in the process of BJ-B11-induced apoptosis. Taken together, our data provide a putative molecular mechanism for the anticancer effect of BJ-B11 on K562 cells, and suggest a potential application for BJ-B11 in chronic myeloid leukemia therapy.

Effects of 1,2,4,6-tetra-O-galloyl-β-D-glucose from P. emblica on HBsAg and HBeAg Secretion in HepG2.2.15 Cell Culture*

A polyphenolic compound, 1,2,4,6-tetra-O-galloyl-β-D-glucose (1246TGG), was isolated from the traditional Chinese medicine Phyllanthus emblica L. (Euphorbiaceae) and assayed for its potential as an anti-hepatitis B virus (HBV) agent. The cytotoxicity of 1246TGG on HepG2.2.15 as well as HepG2 cells was determined by observing cytopathic effects, and the effects of 1246TGG on secretion of HBsAg and HBeAg in HepG2.2.15 cells were assayed by enzyme immunoassay. Results indicates that treatment with 1246TGG (6.25 μg/mL, 3.13 μg/mL), reduced both HBsAg and HBeAg levels in culture supernatant, yet the inhibitory effects tend to decline with the assay time. This study provides a basis for further investigation of the anti-HBV activity and possible mechanism of action of 1246TGG.

Cloning, soluble expression, rapid purification and characterization of human Cofilin1

Cofilin1 is an actin-binding protein that plays a critical role in the regulation of actin cytoskeleton and consequently affects various physiological processes. In this study, the human Cofilin1 cDNA was cloned into the expression vector pET-28a(+) with a 6 × His tag and expressed as soluble protein in Escherichia coli BL21(DE3). Approximately 78 mg of Cofilin1, which showed high activity as determined by native PAGE, could be purified from each liter of LB medium by His-tag affinity chromatography and gel filtration. Further, high-titer IgG against Cofilin1 was positively detected after immunization in rabbits and the polyclonal antibodies were purified and identified. Together, this report provides the first protocol to efficiently obtain human Cofilin1 with high biological activity and immunogenicity using E. coli BL21 (DE3) expression system.