Functional Characterization of Two RNA Methyltransferase Genes METTL3 and METTL14 Uncovers the Roles of m6A in Mediating Adaptation of Plutella xylostella to Host Plants.

N6-methyladenosine (m6A) is one of the major epigenetic modifications in eukaryotes. Although increasing functions of m6A have been identified in insects, its role in Plutella xylostella L. for host plant adaptation remains unclear. In the current study, we show that the m6A content of P. xylostella was relatively low in different developmental stages and tissues, with no significant differences. Two RNA methyltransferase genes, PxMETTL3 (methyltransferase-like 3) and PxMETTL14 (methyltransferase-like 14), were identified and characterized. PxMETTL3 could be transcribed into two transcripts, and PxMETTL14 had only one transcript; both of these genes were highly expressed in egg and adult stages and reproductive tissues. The CRISPR/Cas9-mediated knockout of PxMETTL3 (ΔPxMETTL3-2) or PxMETTL14 (ΔPxMETTL14-14) confirmed their function in m6A installation into RNA. Furthermore, upon transfer from an artificial diet to the host plant, the mutant strains were affected in terms of larval and pupal weight or adult emergence rate, while the wildtype (WT) strain did not exhibit any difference. In addition, the fecundity and egg hatching rate of the WT strain decreased significantly, whereas only the ΔPxMETTL14-14 mutant strain displayed significantly decreased fecundity. There seemed to be a tradeoff between the stress adaptation and reproduction in P. xylostella mediated by m6A modification. During host transfer, the expression of PxMETTL14 was consistent with the change in m6A content, which implied that PxMETTL14 could respond to host plant defense effectively, and may regulate m6A content. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of the differentially expressed transcripts with changes in m6A levels revealed that the potential functions of m6A-related genes may be involved in steroid biosynthesis for larval performance and metabolic pathways for adult reproduction. Overall, our work reveals an epigenetic regulation mechanism for the rapid adaptation of P. xylostella to variations in the host environment.

[Prevalence and causes of blindness and moderate and severe visual impairment among adults aged 50 years or above in Longyao County of Hebei Province:the China Nine-Province survey].

OBJECTIVE: To investigate the prevalence and causes of blindness and moderate and severe visual impairment among adults aged ≥ 50 years in Longyao County, Hebei Province, China. METHODS: It was a population-based cross-section study.Geographically defined cluster sampling was used in randomly selecting 5527 individuals aged ≥ 50 years in Longyao County. The survey was preceded by a pilot study where operational methods were refined and quality assurance evaluation was carried out. All participants were enumerated through village registers followed door-to-door visits.Eligible individuals were invited to receive visual acuity measurement and eye examination. Prevalence of blindness and moderate and severe visual impairment was calculated according to different age, gender or education. And the reasons of blindness were analyzed.Statistical analyses were performed using Stata/SE Statistical Software, release 9.0. Chi-square test was used to investigate the association of age, gender and education with presenting and best corrected visual acuity. RESULTS: Five thousands five hundreds and twenty-seven individuals were enumerated and 5051 persons were examined, the response rate was 91.39%. Based on the criteria of World Health Organization visual impairment classification in 1973, the prevalence of blindness and moderate and severe visual impairment defined as best corrected visual acuity was 1.05% (53/5051) and 3.46% (175/5051) respectively. The prevalence of blindness and moderate and severe visual impairment defined as presenting visual acuity was 1.48% (75/5051) and 7.94% (401/5051) respectively. The prevalence of blindness and moderate and severe visual impairment was higher in aged (trend χ(2) = 897.27, P = 0.000) , female (χ(2) = 30.32, P = 0.000), illiterate (trend χ(2) = 83.20, P = 0.000) persons. Cataract was still the first leading cause of blindness. Un-corrected refractive error also was the main cause of visual impairment. CONCLUSIONS: The prevalence of blindness and moderate and severe visual impairment is relatively lower among China Nine Province Survey. The first leading cause of blindness and visual impairment is still cataract.

Inhibition of Obtusifolin on retinal pigment epithelial cell growth under hypoxia.

AIM: To explore the effect of Obtusifolin on retinal pigment epithelial cell growth under hypoxia. METHODS: In vitro chemical hypoxia model of ARPE-19 cells was established using cobalt chloride (CoCl2). Cell viability was tested by cell counting kit-8 (CCK-8) assay. Western blot and real-time quantitative polymerase chain reaction were applied to detect proteins and mRNAs respectively. Flow cytometry was used to examine the cell cycle. Secretion of vascular endothelial growth factor (VEGF) was tested by using enzyme linked immunosorbent assay (ELISA). RESULTS: Under the chemical hypoxia model established by CoCl2, hypoxia inducible factor-1α (HIF-1α) mRNA and protein levels was up-regulated. Cell viability was increased and the proportion of S phase was higher. Obtusifolin could reduce cell viability under hypoxic conditions and arrest cells in G1 phase. Obtusifolin reduced the expression of Cyclin D1 and proliferating cell nuclear antigen (PCNA) in the hypoxic environment and increased the expression of p53 and p21. The levels of VEGF, VEGFR2 and eNOS proteins and mRNA were significantly increased under hypoxia while Obtusifolin inhibited the increasing. CONCLUSION: Obtusifolin can inhibit cell growth under hypoxic conditions and down-regulate HIF-1/VEGF/eNOS secretions in ARPE-19 cells.

Effects of tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) on the activation of ERK1/2 MAP kinases and the proliferation of human mammary epithelial cells.

Cigarette smoking is a risk factor in the developing of various cancers including breast tumors. There are more than 60 chemical carcinogens in the cigarette smoke; 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) being one of the strongest tobacco-specific carcinogens. In this study, we demonstrated that NNK rapidly activated ERK1 and ERK2 MAP kinases and stimulated proliferation in human normal mammary epithelial cells. MEK1/2 specific inhibitor UO126 completely blocked NNK-induced ERK1/2 activation and cell proliferation, whereas nicotinic receptor nAchR antagonist mecamylamine partially and the selective α(7)-nAchR antagonist α-bungarotoxin essentially inhibited the NNK-induced ERK1/2 activation and cell proliferation. Surprisingly, receptor tyrosine kinase inhibitor genistein, the selective ß(1)-adrenergic antagonist atenolol, and the selective ß(2)-adrenergic antagonist ICI118.551 had a strong inhibitory effect on ERK1/2 activation and cell proliferation induced by NNK. These results suggest that there are at least two different routes in activating ERK1/2 by NNK. One is through nicotinic receptor α(7)-nAchR to MEK1/2; the other is from ß(1)/ß(2)-adrenergic transactivation of tyrosine kinase containing receptor(s) to MEK1/2. In human cancer mammary epithelial cell lines, we found that ERK MAPK signaling pathway was deregulated: (1) ERK1/2 was constitutively activated at various levels; (2) ERK1/2 was further significantly activated in response to NNK induction; (3) UO126 partially or totally failed to inhibit ERK1/2 activation induced by NNK; (4) The expression levels of ERK1/2 in the cancer cell lines were much higher than those in the normal mammary epithelial cells. The tobacco-specific carcinogen NNK showed a strong proliferative effect on human normal and cancer mammary epithelial cells; the proliferation multitudes of these cells are well correlated with the activation levels of ERK1/2 MAP kinases.

Intestine-derived Clostridium leptum induces murine tolerogenic dendritic cells and regulatory T cells in vitro.

Patients with autoimmune and allergic diseases frequently present with reduced numbers and functionally impaired regulatory T cells (Tregs) and/or tolerogenic dendritic cells (tDCs). tDC-mediated regulation of Treg proliferation (numbers) and activation is crucial to establishing and maintaining an appropriate level of immune tolerance. Colonic colonization of Clostridium spp. is associated with accumulation of Tregs, which inhibits development of inflammatory lesions. To investigate whether infection with the Clostridium leptum sp. can specifically induce Tregs and/or tDCs bone marrow-derived dendritic cells were cultured in the presence or absence of C. leptum then co-cultured with CD4(+)CD25(-) T cells or not. Changes in tDC numbers, Treg numbers, percentages of T cell subsets, and expression of cytokines related to Tregs (IL-10 and transforming growth factor-beta (TGF-ß1)), DCs (IL-12p40 and IL-6) and effector T cells (IFN-γ, IL-4, IL-5, IL-13, and IL-17A) were measured. In the co-culture system, C. leptum-stimulated tDCs were able to increase the percentage and total number of Tregs attenuate activation of T helper cells (Th1, Th2, and Th17), and decrease the amount of secreted IL-4, IL-5, IL-13, IFN-γ and IL-17A. Thus, C. leptum exposure can induce the tDC-mediated stimulation of Tregs while disrupting the immune inflammatory response mediated by Th1, Th2 and Th17 cells.