Corrigendum: Development and Evaluation of Stable Sugarcane Mosaic Virus Mild Mutants for Cross-Protection Against Infection by Severe Strain.

[This corrects the article DOI: 10.3389/fpls.2021.788963.].

A maize triacylglycerol lipase inhibits sugarcane mosaic virus infection.

Triacylglycerol lipase (TGL) plays critical roles in providing energy for seed germination and plant development. However, the role of TGL in regulating plant virus infection is largely unknown. In this study, we adopted affinity purification coupled with mass spectrometry and identified that a maize (Zea mays) pathogenesis-related lipase protein Z. mays TGL (ZmTGL) interacted with helper component-proteinase (HC-Pro) of sugarcane mosaic virus (SCMV). Yeast two-hybrid, luciferase complementation imaging, and bimolecular fluorescence complementation assays confirmed that ZmTGL directly interacted with SCMV HC-Pro in vitro and in vivo. The 101-460 residues of SCMV HC-Pro were important for its interaction with ZmTGL. ZmTGL and SCMV HC-Pro co-localized at the mitochondria. Silencing of ZmTGL facilitated SCMV infection, and over-expression of ZmTGL reduced the RNA silencing suppression activity, most likely through reducing HC-Pro accumulation. Our results provided evidence that the lipase hydrolase activity of ZmTGL was associated with reducing HC-Pro accumulation, activation of salicylic acid (SA)-mediated defense response, and inhibition of SCMV infection. We show that ZmTGL inhibits SCMV infection by reducing HC-Pro accumulation and activating the SA pathway.

Development and Evaluation of Stable Sugarcane Mosaic Virus Mild Mutants for Cross-Protection Against Infection by Severe Strain.

Sugarcane mosaic virus (SCMV; genus Potyvirus) induces maize dwarf mosaic disease that has caused serious yield losses of maize in China. Cross-protection is one of the efficient strategies to fight against severe virus strains. Although many mild strains have been identified, the spontaneous mutation is one of the challenging problems affecting their application in cross-protection. In this study, we found that the substitution of cysteine (C) at positions 57 or 60 in the zinc finger-like motif of HC-Pro with alanine (A; C57A or C60A) significantly reduced its RNA silencing suppression activity and SCMV virulence. To reduce the risk of mild strains mutating to virulent ones by reverse or complementary mutations, we obtained attenuated SCMV mutants with double-mutations in the zinc finger-like and FRNK motifs of HC-Pro and evaluated their potential application in cross-protection. The results showed that the maize plants infected with FKNK/C60A double-mutant showed symptomless until 95 days post-inoculation and FKNK/C60A cross-protected plants displayed high resistance to severe SCMV strain. This study provides theoretical and material bases for the control of SCMV through cross-protection.

[The Roles of Icariin on the Proliferation and Apoptosis Abilities of Human Oophoroma Cells and Multi-drug Resistant Cell Line].

OBJECTIVE: To explore the effects of icariin on the proliferation and apoptosis abilities of human ovarian cancer cells SKOV3 and multi-drug resistant SKVCR cells. METHODS: Human ovarian cancer cells SKOV3 and multi-drug resistant SKVCR cells were treated with various concentrations of icariin. The inhibitory concentration and the half maximal inhibitory concentration were detected by CCK8 kit. The proliferation and apoptosis abilities of SKOV3 and SKVCR cells were measured by flow cytometry. The migration and invasion abilities of SKOV3 and SKVCR cells were evaluated by Transwell assays. The protein expression level of Caspase-3 was detected by Western blot analysis. RESULTS: Icariin significantly suppressed the proliferation abilities of SKOV3 and SKVCR cells in a dose-dependent manner at variant levels from 5-100 µg/mL. SKOV3 and SKVCR cells were treated with 19.5 µg/mL icariin and 48.4 µg/mL icariin (0.8×IC50) for 48 h, respectively. The results showed that the cell proliferation, migration and invasion abilities were markedly decreased comparing with control group, and the apoptosis rate was significantly increased as compared with control group (P<0.05). Western blot results indicated that icariin significantly increased the protein expression level of caspase-3 in SKOV3 and SKVCR cells (P<0.05). CONCLUSION: Icariin suppressed the proliferation, migration and invasion abilities of human ovarian cancer cells. Increasing expression of Caspase-3 might be the mechanism of its enhancement of apoptosis.

microRNA­802 promotes lung carcinoma proliferation by targeting the tumor suppressor menin.

microRNAs play important roles in numerous biological processes, including tumorigenesis, by modulating critical gene transcripts. In the present study, the role of microRNA­802 (miR­802) in lung cancer was investigated. The results of the quantitative polymerase chain reaction revealed that expression levels of miR­802 were significantly upregulated in lung cancer tissues. In vitro experiments demonstrated that miR­802 promoted cell proliferation in A549, NCI­H358 and NCI­H1299 cells. Furthermore, it was indicated that miR­802 promoted the proliferation of lung carcinoma by targeting the tumor suppressor menin. Therefore, these results suggest a previously unknown miR­802/menin molecular network controlling lung carcinoma development.

3-D culture of human umbilical vein endothelial cells with reversible thermosensitive hydroxybutyl chitosan hydrogel.

The aim of this study was to present a non-trypsin 3D cell culture method with a reversible thermosensitive HBCS hydrogel. In this study, hydroxybutyl chitosan (HBCS) was synthesized by grafting hydroxybutyl groups on chitosan molecule chains. The prepared HBCS was water-soluble, and the reversible phase transformation temperature was 26 °C. Scanning electron microscope images illuminated the 3-D network of hydrogel formed irregular porous structure which ranged from 50-250 µm. Cell viability assay indicated that HBCS solution could promote the proliferation of human umbilical vein endothelial cells (HUVECs), and the boost of proliferation was enhanced with the increase of HBCS concentration. HBCS had no harm to the nitric oxide (NO) synthesis functionality of HUVECs. HUVECs could grow and reproduce inside the hydrogel, and showed good vitality after 14-days culture. Meanwhile, cells cultured inside the hydrogel could be passaged successively through the reversible phase transformation process of HBCS. The results revealed that HBCS have the potential to be used for 3-D cell culture without the use of trypsin.