Inhibitory effect of traditional herbal (kampo) medicines on the replication of human parainfluenza virus type 2 in vitro.

Thirteen herbal medicines, Kakkonto (TJ-001), Kakkontokasenkyushin'i (TJ-002), Hangekobokuto (TJ-016), Shoseiryuto (TJ-019), Maoto (TJ-027), Bakumondoto (TJ-029), Hochuekkito (TJ-041), Goshakusan (TJ-063), Kososan (TJ-070), Chikujountanto (TJ-091), Gokoto (TJ-095), Saibokuto (TJ-096), and Ryokankyomishingeninto (TJ-119) were tested for human parainfluenza virus type 2 (hPIV-2) replication. Eight (TJ-001, TJ-002, TJ-019, TJ-029, TJ-041, TJ-063, TJ-095 and TJ-119) out of the thirteen medicines had virus growth inhibitory activity. TJ-001 and TJ-002 inhibited virus release, and largely inhibited genome, mRNA and protein syntheses. TJ-019 slightly inhibited virus release, inhibited gene and mRNA syntheses, and largely inhibited protein synthesis. TJ-029 slightly inhibited virus release, largely inhibited protein synthesis, but gene and mRNA syntheses were unaffected. TJ-041 only slightly inhibited virus release, the gene and mRNA syntheses, but largely inhibited protein synthesis. TJ-091 largely inhibited gene, mRNA and protein syntheses. TJ-095 largely inhibited gene synthesis, but NP and HN mRNAs were slightly detected, and protein syntheses were observed. TJ-119 inhibited gene, mRNA and protein syntheses. TJ-001, TJ-002, TJ-091, TJ-095 and TJ-119 inhibited multinucleated giant cell formation derived from cell-to-cell spreading of virus. However, in TJ-019, TJ-029 and TJ-041 treated infected cells, only small sized fused cells with some nuclei were found. TJ-019 and TJ-041 slightly disrupted actin microfilaments, and TJ-001 and TJ-002 destroyed them. TJ-041 slightly disrupted microtubules, and TJ-001 and TJ-002 disrupted them. In general, the medicines effective on common cold and bronchitis inhibited hPIV-2 replication.

Loss of the small GTPase Arl8b results in abnormal development of the roof plate in mouse embryos.

Lysosomes are acidic organelles responsible for degrading both exogenous and endogenous materials. The small GTPase Arl8 localizes primarily to lysosomes and is involved in lysosomal function. In the present study, using Arl8b gene-trapped mutant (Arl8b-/- ) mice, we show that Arl8b is required for the development of dorsal structures of the neural tube, including the thalamus and hippocampus. In embryonic day (E) 10.5 Arl8b-/- embryos, Sox1 (a neuroepithelium marker) was ectopically expressed in the roof plate, whereas the expression of Gdf7 and Msx1 (roof plate markers) was reduced in the dorsal midline of the midbrain. Ectopic expression of Sox1 in Arl8b-/- embryos was detected also at E9.0 in the neural fold, which gives rise to the roof plate. In addition, the levels of Bmp receptor IA and phosphorylated Smad 1/5/8 (downstream of BMP signaling) were increased in the neural fold of E9.0 Arl8b-/- embryos. These results suggest that Arl8b is involved in the development of the neural fold and the subsequently formed roof plate, possibly via control of BMP signaling.

Netrin-4 regulates thalamocortical axon branching in an activity-dependent fashion.

Axon branching is remodeled by sensory-evoked and spontaneous neuronal activity. However, the underlying molecular mechanism is largely unknown. Here, we demonstrate that the netrin family member netrin-4 (NTN4) contributes to activity-dependent thalamocortical (TC) axon branching. In the postnatal developmental stages of rodents, ntn4 expression was abundant in and around the TC recipient layers of sensory cortices. Neuronal activity dramatically altered the ntn4 expression level in the cortex in vitro and in vivo. TC axon branching was promoted by exogenous NTN4 and suppressed by depletion of the endogenous protein. Moreover, unc-5 homolog B (Unc5B), which strongly bound to NTN4, was expressed in the sensory thalamus, and knockdown of Unc5B in thalamic cells markedly reduced TC axon branching. These results suggest that NTN4 acts as a positive regulator for TC axon branching through activity-dependent expression.

Ribavirin inhibits human parainfluenza virus type 2 replication in vitro.

The antiviral activities of eight nucleoside analog antiviral drugs (ribavirin, acyclovir, lamivudine, 3'-azido-3'-deoxythymidine, emtricitabine, tenofovir, penciclovir and ganciclovir) against human parainfluenza virus type 2 (hPIV-2) were investigated. Only ribavirin (RBV) inhibited both cell fusion and hemadsorption induced by hPIV-2. RBV considerably reduced the number of viruses released from the cells. Virus genome synthesis was inhibited by RBV, as determined by real time PCR. An indirect immunofluorescence study showed that RBV largely inhibited viral protein synthesis. mRNAs of the proteins were not detected, indicating that inhibition of protein synthesis was caused by transcription inhibition by RBV. Using a recombinant green fluorescence protein-expressing hPIV-2 without matrix protein, it was found that RBV did not completely inhibit virus entry into the cells; however, it almost completely blocked multinucleated giant cell formation. RBV did not disrupt actin microfilaments and microtubules. These results indicate that the inhibitory effect of RBV is caused by inhibition of both virus genome and mRNA synthesis, resulting in inhibition of virus protein synthesis, viral replication and multinucleated giant cell formation (extensive cell-to-cell spreading of the virus).