Junsub Lee

Genetic analysis of the VP1 region of Human enterovirus 71 strains isolated in Korea during 2000

Summary.u2002We have isolated Human enterovirus 71 (EV71) from stool and CSF samples taken from patients with acute flaccid paralysis, herpangina, or hand, foot and mouth disease in 2000. Both the cell culture-neutralization test and RT-PCR were used to detect enteroviruses. Rhabdomyosarcoma (RD), HEP2c, and BGM cells were used for the isolation of viruses, and serotypes were determined by the neutralization test using EV71-specific antiserum. For genomic analysis, we amplified a 437-bp fragment of the 5′-noncoding region of the enterovirus genome and a 484-bp fragment of the VP3/VP1 region of EV71 by RT-PCR, with positive results. Products amplified using an EV71-specific primer pair were sequenced and compared with other isolates of EV71. Analysis of the nucleotide sequences of the amplified fragments showed that the EV71 isolates from patients were over 98% homologous and belonged to the genotype C.

Upregulation of Nrf2 expression by human cytomegalovirus infection protects host cells from oxidative stress.

NF-E2 related factor 2 (Nrf2) is a transcription factor that plays a key role(s) in cellular defence against oxidative stress. In this study, we showed that the expression of Nrf2 was upregulated in primary human foreskin fibroblasts (HFFs), following human cytomegalovirus (HCMV/HHV-5) infection. The expression of haem oxygenase-1, a downstream target of Nrf2, was also increased by HCMV infection, and this induction was suppressed in HFFs expressing a small hairpin RNA (shRNA) against Nrf2. The HCMV-mediated increase in Nrf2 expression was abolished when UV-irradiated virus was used or when the activity of casein kinase 2 was inhibited. Host cells infected by HCMV had higher survival rates following oxidative stress induced by buthionine sulfoximine compared with uninfected control cells, but this cell-protective effect was abolished by the use of Nrf2 shRNA. Our results suggest that HCMV-mediated activation of Nrf2 might be beneficial to the virus by increasing the host cells ability to cope with oxidative stress resulting from viral infection and/or inflammation.

Functional response of Neoseiulus californicus (Acari: Phytoseiidae) to Tetranychus urticae (Acari: Tetranychidae) on strawberry leaves.

Neoseiulus californicus (McGregor) is a predatory mite employed for biological control of the agricultural pest Tetranychus urticae (Koch). We explored whether environmental differences, in this case the trichome densities of abaxial leaf surfaces of strawberry cultivars (‘Maehyang’ and ‘Sulhyang’ varieties) affect the functional response of adult female N. californicus preying on immature stages (egg, larva and nymph) of T. urticae. We also evaluated the functional response of N. californicus to eggs of T. urticae at different temperatures (15, 20, 25, 30 and 35°C). We conducted a logistic regression of the proportion of prey consumed as a function of initial prey density to identify functional response types, and used nonlinear least‐squares regression and the random predator equation to estimate attack rates and handling times. The functional response of adult female N. californicus to T. urticae was not influenced by non‐glandular trichomes on abaxial leaves but was affected by temperature. Overall, adult female N. californicus exhibited a type 2 functional response to T. urticae. The handling time of N. californicus was highest (1.9970u2003h) against T. urticae nymphs. The attack rate did not change much at 15–30°C, but was significantly higher at 35°C. The handling time decreased significantly with increasing temperature at 15–35°C. At 35°C, the attack rate was highest (0.2087) and the handling time was lowest (0.9511u2003h).

Interferon-gamma inhibits the neuronal differentiation of neural progenitor cells by inhibiting the expression of Neurogenin2 via the JAK/STAT1 pathway

Interferon-gamma (IFN-γ) is one of the critical cytokines released by host immune cells upon infection. Despite the important role(s) of IFN-γ in host immune responses, there has been no in vivo study regarding the effects of IFN-γ on brain development, and the results from many in vitro studies are controversial. In this study, the effects of IFN-γ on embryonic neurogenesis were investigated. Treatment of E14.5 mouse neural progenitor cells (NPCs) with IFN-γ resulted in a decrease in the percentage of TuJ1-positive immature neurons but an increase in the percentage of Nestin-positive NPCs. Similar results were obtained in vivo. Treatment of NPCs with a JAK inhibitor or the knockdown of STAT1 expression abrogated the IFN-γ-mediated inhibition of neurogenesis. Interestingly, the expression of one of proneural genes, Neurogenin2 (Neurog2) was dramatically inhibited upon IFN-γ treatment, and cells overexpressing Neurog2 did not respond to IFN-γ. Taken together, our results demonstrate that IFN-γ inhibits neuronal differentiation of NPCs by negatively regulating the expression of Neurog2 via the JAK/STAT1 pathway. Our findings may provide an insight into the role of IFN-γ in the development of embryonic brain.

PG201 downregulates the production of nitrite by upregulating heme oxygenase-1 expression through the control of phosphatidylinositol 3-kinase and NF-E2-related factor 2.

PG201 is an ethanol extract prepared from a specially designed botanical formulation and has previously been shown to contain strong anti-arthritic activities by controlling inflammation and cartilage destruction in two animal models [1,2]. In the present study, we evaluated the effects of PG201 on the expression of heme oxygenase-1 (HO-1). The treatment of Raw264.7 cells (a murine macrophage cell line) and bone marrow-derived macrophages (BMDMs) with PG201 increased the protein and RNA levels of HO-1. The results from a reporter plasmid assay indicated that PG201 induced HO-1 promoter activity through the stress response element present in the two enhancers of the HO-1 promoter. The treatment of cells with PG201 increased the total amount and the nuclear level of NF-E2-related factor 2 (Nrf2). Protein analysis using BMDMs from Nrf2 knockout mice showed that Nrf2 was necessary for the PG201-mediated induction of HO-1 expression. The PG201-mediated induction of these anti-oxidative stress factors was inhibited by a specific inhibitor of phosphatidylinositol 3-kinase (PI3K), but not by inhibitors of p38, ERK and JNK mitogen-activated protein kinases. Furthermore, the results from an experiment involving a specific siRNA and chemical inhibitors for HO-1 showed that the PG201-mediated increase of the HO-1 protein contributed to the suppression of inducible nitric oxide synthase (iNOS) and nitrite production stimulated by lipopolysaccharide. Taken together, these results suggest that PG201 activates Nrf2 through the PI3K signal transduction pathway, increases the expression of HO-1, and subsequently decreases the production of iNOS and nitrite, eventually exerting anti-inflammatory activities.

Age‐ and temperature‐dependent oviposition model of Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) with Tetranychus urticae as prey

In this study, we developed an oviposition model of Neoseiulus californicus (McGregor) with Tetranychus urticae Koch as prey. To obtain data for the model, we investigated the longevity, fecundity and survivorship of adult female N. californicus at six constant temperatures (16, 20, 24, 28, 32 and 36°C), 60–70% RH and a photoperiod of 16u2003:u20038 (Lu2003:u2003D) h. Longevity (averageu2003±u2003SE) decreased as temperature increased and was longest at 16°C (46.7u2003±u20035.25u2003days) and shortest at 36°C (12.8u2003±u20030.75u2003days). Adult developmental rate (1/average longevity) was described by the Lactin 1 model (r2u2003=u20030.95). The oviposition period (average±SE) was also longest at 16°C (29.8u2003±u20032.93u2003days) and shortest at 36°C (6.7u2003±u20030.54u2003days). Fecundity (average±SE) was greatest at 24°C (43.8u2003±u20033.23 eggs) and lowest at 36°C (15.9u2003±u20031.50 eggs). The oviposition model comprised temperature‐dependent fecundity, age‐specific cumulative oviposition rate and age‐specific survival rate functions. The temperature‐dependent fecundity was best described by an exponential equation (r2u2003=u20030.81). The age‐specific cumulative oviposition rate was best described by the three‐parameter Weibull function (r2u2003=u20030.96). The age‐specific survival rate was best described by a reverse sigmoid function (r2u2003=u20030.85).

Si-based magnetic tunnel transistor with single CoFe base layer

Magnetic tunnel transistors were prepared on Si(100) substrates by magnetron sputter deposition. By means of spin filtering through a single Co90Fe10 base layer, magnetocurrent ratios of 53%–55% and high transfer ratios of (1–2)×10−4 for emitter-base bias of 1.5–2V were obtained at 77K. The bias dependence of the collector current showed the square-law behavior. From the modified Bell-Kaiser model, attenuation lengths of majority and minority spins of hot electrons are expected as 40±5 and 16±1A in the single Co90Fe10 layer, respectively. The decrease of transfer ratio was observed with decreasing base thickness from 80 to 30A, which may be related to the extension of the (Co2Si and Fe) intermediate region formed at Co90Fe10∕Si interface in the thinner base layer.

Effective control of neuropathic pain by transient expression of hepatocyte growth factor in a mouse chronic constriction injury model

Hepatocyte growth factor (HGF) is a multifunctional protein that contains angiogenic and neurotrophic properties. In the current study, we investigated the analgesic effects of HGF by using a plasmid DNA that was designed to express 2 isoforms of human HGF—pCK‐HGF‐X7 (or VM202)—in a chronic constriction injury (CCI)‐ induced mouse neuropathic pain model. Intramuscular injection of pCK‐HGF‐X7 into proximal thigh muscle induced the expression of HGF in the muscle, sciatic nerve, and dorsal root ganglia (DRG). This gene transfer procedure significantly attenuated mechanical allodynia and thermal hyperalgesia after CCI. Injury‐induced expression of activating transcription factor 3, calcium channel subunit α2δ1, and CSF1 in the ipsilateral DRG neurons was markedly down‐regulated in the pCK‐HGF‐X7‐treated group, which suggested that HGF might exert its analgesic effects by inhibiting pain‐mediating genes in the sensory neurons. In addition, suppressed CSF1 expression in DRG neurons by pCK‐HGF‐X7 treatment was accompanied by a noticeable suppression of the nerve injury‐induced glial cell activation in the spinal cord dorsal horn. Taken together, our data show that pCK‐HGF‐X7 attenuates nerve injury‐induced neuropathic pain by inhibiting pain‐related factors in DRG neurons and subsequent spinal cord glial activation, which suggests its therapeutic efficacy in the treatment of neuropathic pain.—Nho, B., Lee, J., Lee, J., Ko, K. R., Lee, S. J., Kim, S. Effective control of neuropathic pain by transient expression of hepatocyte growth factor in a mouse chronic constriction injury model. FASEB J. 32, 5119–5131 (2018). www.fasebj.org

Regulation of CCAAT/enhancer-binding protein (C/EBP) α in human-cytomegalovirus-infected fibroblasts.

CCAAT/enhancer-binding protein (C/EBP) α, a member of the C/EBP family of transcription factors, is known to be involved in gene expression and DNA replication of human cytomegalovirus (HCMV). This study aimed to understand the regulation of endogenous C/EBPα during HCMV infection using an in vitro infection model. The expression and localization of C/EBPα were investigated in fibroblasts infected with HCMV. The overexpression of C/EBP homologous protein (CHOP), the endogenous inhibitor of C/EBP, was also employed to test the involvement of C/EBPα during HCMV infection. Our data showed that HCMV infection increases the expression of the full-length C/EBPα isoform (p42) especially during the late stage of infection at the transcriptional and post-translational levels. The increased p42 accumulated in the viral DNA replication compartment. p42 expression was not induced in cells treated with UV-irradiated virus or in cells infected with normal virus in the presence of ganciclovir. CHOP-mediated inhibition of C/EBP activity suppressed viral gene expression and DNA replication, which lowered the level of viral production. Together, our data suggest that HCMV-mediated C/EBPα regulation might play a beneficial role in the lytic cycle of HCMV.

Effective suppression of nitric oxide production by HX106N through transcriptional control of heme oxygenase-1

Heme oxygenase-1 (HO-1) has been suggested to be a key neuroprotective enzyme because of its widespread distribution in the brain as well as its strong antioxidative effects. HX106N, a water-soluble botanical formulation, has previously been demonstrated to prevent amyloid β-induced memory impairment and oxidative stress in mice by upregulating HO-1 levels. In this study, the underlying molecular mechanisms of HX106N-induced HO-1 expression were investigated using BV-2 cells, a murine microglial cell line, and primary microglia. Treatment with HX106N induced the expression of HO-1 at the transcriptional level through the stress-responsive element-containing enhancer present in the ho-1 promoter. Nuclear factor E2-related factor 2 (Nrf2) was activated in cells treated with HX106N. The results from knockdown assay showed that small interfering RNA of Nrf2 attenuated HX106N-mediated HO-1 expression. Pharmacological inhibitors of p38 and JNK mitogen-activated protein kinases suppressed the HX106N-mediated induction of HO-1. The NF-κB signaling pathway was activated by HX106N and played a role in HX106N-induced HO-1 expression. Furthermore, HO-1 and one of its by-products during the enzymatic degradation of heme, CO, were found to be involved in HX106N-mediated suppression of NO production. Taken together, these data indicate that HX106N exerts potent antioxidative effects by increasing the expression of HO-1 through multiple signaling pathways, leading to the suppression of NO production.