Methyltransferase-like 3 aggravates endoplasmic reticulum stress in preeclampsia by targeting TMBIM6 in YTHDF2-dependent manner.

BACKGROUND: With the increasing morbidity and mortality of preeclampsia (PE), it has posed a huge challenge to public health. Previous studies have reported endoplasmic reticulum (ER) stress could contribute to trophoblastic dysfunction which was associated with the N6-methyladenosine (m6A) modification by methyltransferase-like 3 (METTL3), resulting in PE. However, little was known about the relationship between METTL3 and ER stress in PE. Thus, in vitro and in vivo studies were performed to clarify the mechanism about how METTL3 affects the trophoblasts under ER stress in PE and to explore a therapeutic approach for PE. METHODS: An ER stress model in HTR-8/SVneo cells and a preeclamptic rat model were used to study the mechanism and explore a therapeutic approach for PE. Western blot, immunohistochemistry, quantitative reverse transcription-polymerase chain reaction (qRT-PCR), and methylated RNA immunoprecipitation (MeRIP)-qPCR were performed to detect the protein, RNA, and methylated transmembrane BAX inhibitor motif containing 6 (TMBIM6) expression levels. The m6A colorimetric and mRNA stability assays were used to measure the m6A levels and TMBIM6 stability, respectively. Short hairpin RNAs (shRNAs) were used to knockdown METTL3 and YTH N6-methyladenosine RNA binding protein 2 (YTHDF2). Flow cytometry and Transwell assays were performed to evaluate the apoptosis and invasion abilities of trophoblasts. RESULTS: Upregulated METTL3 and m6A levels and downregulated TMBIM6 levels were observed in preeclamptic placentas under ER stress. The ER stress model was successfully constructed, and knockdown of METTL3 had a beneficial effect on HTR-8/SVneo cells under ER stress as it decreased the levels of methylated TMBIM6 mRNA. Moreover, overexpression of TMBIM6 was beneficial to HTR-8/SVneo cells under ER stress as it could neutralize the harmful effects of METTL3 overexpression. Similar to the knockdown of METTL3, downregulation of YTHDF2 expression resulted in the increased expression and mRNA stability of TMBIM6. Finally, improved systemic symptoms as well as protected placentas and fetuses were demonstrated in vivo. CONCLUSIONS: METTL3/YTHDF2/TMBIM6 axis exerts a significant role in trophoblast dysfunction resulting in PE while inhibiting METTL3 may provide a novel therapeutic approach for PE.

Hydrogen production driven by formate oxidation in Shewanella oneidensis MR-1.

Shewanella oneidensis MR-1 is a potent hydrogen producer in the deficiency of exogenous electron acceptors. The electron transfer pathway for hydrogen production remains unclear, although enzymes for hydrogen production have been identified in S. oneidensis MR-1. In this study, we investigated the electron transfer pathway from formate to hydrogen, given that formate is commonly a key chemical for bacterial hydrogen production. We revealed that two formate dehydrogenases FdhA1B1C1 and FdhA2B2C2, rather than FdnGHI, played a dominant role in formate-driven hydrogen production. Menaquinone was indispensable for the electron transfer from formate to hydrogen, which excluded the presence of formate hydrogen-lyase in S. oneidensis MR-1. A previously proposed formate dehydrogenase subunit HydC was identified as a menaquinone-binding subunit of [FeFe] hydrogenase HydAB, and the hydABC operon is conserved in bacteria living in diverse environments. A formate exporter FocA and transcriptional regulator FhlA were identified for their effect on formate metabolism and hydrogen production. FhlA positively affected the metabolism of formate and hydrogen by regulating the expression of fdhA2B2C2, fdnGHI, focA, and dld-II. Overall, the electron transfer pathway deciphered in this work will facilitate the improvement of biohydrogen production by S. oneidensis MR-1.Key Points• The electron transfer pathway from formate to hydrogen in MR-1 is deciphered.• Menaquinone is indispensable for hydrogen production.• A cytochrome b subunit transfers electrons from menaquinone to [FeFe] hydrogenase.

Gossypium hirsutum Salt Tolerance Is Enhanced by Overexpression of G. arboreum JAZ1.

Gossypium arboreum possesses many favorable traits including robust defense against biotic and abiotic stress although it has been withdrawn from the market because of lower yield and fiber quality compared to G. hirsutum (upland cotton). It is therefore important to explore and utilize the beneficial genes of G. arboretum for G. hirsutum cultivar breeding. Here, the function of G. arboreum JAZ1 in tolerance to salt stress was determined through loss-of-function analysis. GaJAZ1can interact with GaMYC2 to repress expression of downstream genes whose promoters contain a G-box cis element, affecting plant tolerance to salinity stress. The experimental data from NaCl treatments and a 2 year continuous field trial with natural saline-alkaline soil showed that the ectopically overexpressed GaJAZ1 significantly increased salt tolerance in upland cotton compared to the wild type, showing higher growth vigor with taller plants, increased fresh weight, and more bolls, which is due to reprogrammed expression of tolerance-related genes and promotion of root development. High-throughput RNA sequencing of GaJAZ1 transgenic and wild-type plants showed many differentially expressed genes involved in JA signaling and biosynthesis, salt stress-related genes, and hormone-related genes, suggesting that overexpressing GaJAZ1 can reprogram the expression of defense-related genes in G. hirsutum plants to increase tolerance to salt stress. The research provides a foundation to explore and utilize favorable genes from Gossypium species for upland cotton cultivar breeding.

Antifibrotic effects of specific siRNA targeting connective tissue growth factor delivered by polyethyleneimine­functionalized magnetic iron oxide nanoparticles on LX­2 cells.

Connective tissue growth factor (CTGF) is a possible key determinant of progressive fibrosis. Nanotechnology has been considered as a potential tool for developing novel drug delivery systems for various diseases, including liver fibrosis. The present study aimed to investigate the potential antifibrotic activity of CTGF small interfering RNA (siRNA) mediated by polyethyleneimine (PEI)­functionalized magnetic iron oxide (Fe3O4) nanoparticles (NPs) in LX­2 cells. PEI­Fe3O4/siRNA complexes were synthesized to facilitate siRNA delivery and were transfected into LX­2 cells. Laser confocal microscopy was employed to investigate the cell uptake of PEI­Fe3O4/siRNA complexes. Reverse transcription­quantitative PCR (RT­qPCR) and western blotting were used to verify the effect of gene silencing. The results showed that siRNA­loaded PEI­Fe3O4 exhibited low cytotoxicity. The transfection efficiency of PEI­Fe3O4/siRNA reached 73.8%, and RT­qPCR and western blotting demonstrated effective gene silencing. These results indicated that CTGF siRNA delivered by PEI­Fe3O4 NPs significantly reduces CTGF expression and collagen production in activated LX­2 cells, providing a basis for future in vivo studies.

Biodistribution and Toxicity Assessment of Superparamagnetic Iron Oxide Nanoparticles In Vitro and In Vivo.

Biodistribution and toxicity assessment are critical for safe clinical use of newly developed medicines. Superparamagnetic iron oxide nanoparticles (SPION) are effective carriers for targeted drug delivery. This study aimed to examine the toxicity and biodistribution of SPION coated with polyethylenimine (PEI) (SPION-PEI) designed for small interfering RNA (siRNA) delivery both in vitro and in vivo. SPION-PEI/siRNA complexes were prepared at different weight ratios. Cytotoxic effects of SPION-PEI/siRNA on HSC-T6 cell viability were determined by using 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT). Rats were divided into three groups: a control group, a normal-saline group and a SPION-PEI/siRNA group. After a single intravenous injection, in vivo nanoparticle biodistribution and accumulation were evaluated by Prussian blue staining in the heart, liver, spleen, lung and kidney 8 h, 24 h, and 7 days after the injection. Their distribution was histologically studied at the three time points by measuring ironpositive areas (µm2) in organ sections stained with Prussian blue. The same organs were analyzed by H&E staining for any possible histopathological changes. Furthermore, biochemical indexes such as alanine amino transaminase (ALT), aspartate transaminase (AST), blood urea nitrogen (BUN) and creatinine (CREA) were also assessed at all experimental time points. Electrophoresis exhibited that the SPION-PEI could retard siRNA altogether at weight ratios above 4. MTT assay showed that SPION-PEI loaded with siRNA had low cytotoxicity. In vivo study revealed that the liver and spleen were the major sites of SPION-PEI/siRNA deposition. The iron content was significantly increased in the liver and spleen, peaking 24 h after intravenous injection and then declining gradually. No evidence was found of irreversible histopathological damage to any of the organs tested. These results suggested that most SPION-PEI/siRNA complexes were distributed in the liver and spleen, which might be the target organs of SPION-PEI/siRNA complexes. SPIONPEI/siRNA may serve as in vivo carrier for biomedical medicines.

Co-expression network analyses identify functional modules associated with development and stress response in Gossypium arboreum.

Cotton is an economically important crop, essential for the agriculture and textile industries. Through integrating transcriptomic data, we discovered that multi-dimensional co-expression network analysis was powerful for predicting cotton gene functions and functional modules. Here, the recently available transcriptomic data on Gossypium arboreum, including data on multiple growth stages of tissues and stress treatment samples were applied to construct a co-expression network exploring multi-dimensional expression (development and stress) through multi-layered approaches. Based on differential gene expression and network analysis, a fibre development regulatory module of the gene GaKNL1 was found to regulate the second cell wall through repressing the activity of REVOLUTA, and a tissue-selective module of GaJAZ1a was examined in response to water stress. Moreover, comparative genomics analysis of the JAZ1-related regulatory module revealed high conservation across plant species. In addition, 1155 functional modules were identified through integrating the co-expression network, module classification and function enrichment tools, which cover functions such as metabolism, stress responses, and transcriptional regulation. In the end, an online platform was built for network analysis (http://structuralbiology.cau.edu.cn/arboreum), which could help to refine the annotation of cotton gene function and establish a data mining system to identify functional genes or modules with important agronomic traits.

Genome-wide identification and functional analysis of the TIFY gene family in response to drought in cotton.

Jasmonates control many aspects of plant biological processes. They are important for regulating plant responses to various biotic and abiotic stresses, including drought, which is one of the most serious threats to sustainable agricultural production. However, little is known regarding how jasmonate ZIM-domain (JAZ) proteins mediate jasmonic acid signals to improve stress tolerance in cotton. This represents the first comprehensive comparative study of TIFY transcription factors in both diploid A, D and tetraploid AD cotton species. In this study, we identified 21 TIFY family members in the genome of Gossypium arboretum, 28 members from Gossypium raimondii and 50 TIFY genes in Gossypium hirsutum. The phylogenetic analyses indicated the TIFY gene family could be divided into the following four subfamilies: TIFY, PPD, ZML, and JAZ subfamilies. The cotton TIFY genes have expanded through tandem duplications and segmental duplications compared with other plant species. Gene expression profile revealed temporal and tissue specificities for TIFY genes under simulated drought conditions in Gossypium arboretum. The JAZ subfamily members were the most highly expressed genes, suggesting that they have a vital role in responses to drought stress. Over-expression of GaJAZ5 gene decreased water loss, stomatal openings, and the accumulation of H2O2 in Arabidopsis thaliana. Additionally, the results of drought tolerance assays suggested that this subfamily might be involved in increasing drought tolerance. Our study provides new data regarding the genome-wide analysis of TIFY gene families and their important roles in drought tolerance in cotton species. These data may form the basis of future studies regarding the relationship between drought and jasmonic acid.

Transplantation of endothelial progenitor cells for improving placental perfusion in preeclamptic rats.

OBJECTIVE: Effective treatments for preeclampsia are currently unavailable. As endothelial progenitor cell-transplantation may improve ischemia, it is an important undertaking to study the role of endothelial progenitor cells for improving the symptom of preeclampsia. METHOD: Physiological and pathological changes in foetal rats and pregnant rats were monitored. Endothelial progenitor cells were isolated from the peripheral blood of normal rats and labelled by DiI. Endothelial progenitor cells were transplanted into the placenta of preeclampsia-like rats. Fluorescence microscopy was used to observe the differentiation of transplanted endothelial progenitor cells. Western blotting was used to observe the expression of nestin, an index of brain hypoxia in foetal rats. RESULT: The rats suffered from abdominal aortic constriction and NG-nitro-L-arginine methyl ester injection (group F). The proteinuria and blood pressure of pregnant rats in group F increased on the 13th day of pregnancy. The proteinuria and blood pressure of group F was higher than in other groups of rats. The weight of foetal rats and foetal heads significantly decreased in group F compared with other groups. Typical pathological changes of preeclampsia were observed in the placental tissue of group F. In preeclampsia-like rats, transplantation of endothelial progenitor cells led to an increase in placenta angiogenesis. The expression of nestin weakened in endothelial progenitor cell-transplanted rats compared with the non-transplantation group. After EPCs transplantation, physiological parameters in the preeclampsia-like rats were significantly decreased. CONCLUSION: Endothelial progenitor cells transplantation could improve preeclampsia-like symptom in rats and endothelial progenitor cell-transplantation relieves intrauterine hypoxia in brain tissues of foetal rats to a certain extent.

iTRAQ protein profile differential analysis between somatic globular and cotyledonary embryos reveals stress, hormone, and respiration involved in increasing plantlet regeneration of Gossypium hirsutum L.

Somatic embryo development (SED) in upland cotton shows low frequencies of embryo maturation and plantlet regeneration. Progress in increasing the regeneration rate has been limited. Here a global analysis of proteome dynamics between globular and cotyledonary embryos was performed using isobaric tags for relative and absolute quantitation to explore mechanisms underlying SED. Of 6318 proteins identified by a mass spectrometric analysis, 102 proteins were significantly up-regulated and 107 were significantly down-regulated in cotyledonary embryos. The differentially expressed proteins were classified into seven functional categories: stress responses, hormone synthesis and signal transduction, carbohydrate and energy metabolism, protein metabolism, cell wall metabolism, cell transport, and lipid metabolism. KEGG (Kyoto Encyclopedia of Genes and Genomes) analysis showed that stress response, hormone homeostasis, and respiration and photosynthesis were involved in SED. Quantitative real-time PCR analysis confirmed the authenticity and accuracy of the proteomic analysis. Treatment of exogenous hormones showed that abscisic acid and jasmonic acid facilitate SED, whereas gibberellic acid inhibits SED and increases abnormal embryo frequency. Thus, global analysis of proteome dynamics reveals that stress response, hormone homeostasis, and respiration and photosynthesis determined cotton SED. The findings of this research improve the understanding of molecular processes, especially environmental stress response, involved in cotton SED.

Cloning of Gossypium hirsutum sucrose non-fermenting 1-related protein kinase 2 gene (GhSnRK2) and its overexpression in transgenic Arabidopsis escalates drought and low temperature tolerance.

The molecular mechanisms of stress tolerance and the use of modern genetics approaches for the improvement of drought stress tolerance have been major focuses of plant molecular biologists. In the present study, we cloned the Gossypium hirsutum sucrose non-fermenting 1-related protein kinase 2 (GhSnRK2) gene and investigated its functions in transgenic Arabidopsis. We further elucidated the function of this gene in transgenic cotton using virus-induced gene silencing (VIGS) techniques. We hypothesized that GhSnRK2 participates in the stress signaling pathway and elucidated its role in enhancing stress tolerance in plants via various stress-related pathways and stress-responsive genes. We determined that the subcellular localization of the GhSnRK2-green fluorescent protein (GFP) was localized in the nuclei and cytoplasm. In contrast to wild-type plants, transgenic plants overexpressing GhSnRK2 exhibited increased tolerance to drought, cold, abscisic acid and salt stresses, suggesting that GhSnRK2 acts as a positive regulator in response to cold and drought stresses. Plants overexpressing GhSnRK2 displayed evidence of reduced water loss, turgor regulation, elevated relative water content, biomass, and proline accumulation. qRT-PCR analysis of GhSnRK2 expression suggested that this gene may function in diverse tissues. Under normal and stress conditions, the expression levels of stress-inducible genes, such as AtRD29A, AtRD29B, AtP5CS1, AtABI3, AtCBF1, and AtABI5, were increased in the GhSnRK2-overexpressing plants compared to the wild-type plants. GhSnRK2 gene silencing alleviated drought tolerance in cotton plants, indicating that VIGS technique can certainly be used as an effective means to examine gene function by knocking down the expression of distinctly expressed genes. The results of this study suggested that the GhSnRK2 gene, when incorporated into Arabidopsis, functions in positive responses to drought stress and in low temperature tolerance.

mRNA-seq analysis of the Gossypium arboreum transcriptome reveals tissue selective signaling in response to water stress during seedling stage.

The cotton diploid species, Gossypium arboreum, shows important properties of stress tolerance and good genetic stability. In this study, through mRNA-seq, we de novo assembled the unigenes of multiple samples with 3h H(2)O, NaCl, or PEG treatments in leaf, stem and root tissues and successfully obtained 123,579 transcripts of G. arboreum, 89,128 of which were with hits through BLAST against known cotton ESTs and draft genome of G. raimondii. About 36,961 transcripts (including 1,958 possible transcription factor members) were identified with differential expression under water stresses. Principal component analysis of differential expression levels in multiple samples suggested tissue selective signalling responding to water stresses. Venn diagram analysis showed the specificity and intersection of transcripts' response to NaCl and PEG treatments in different tissues. Self-organized mapping and hierarchical cluster analysis of the data also revealed strong tissue selectivity of transcripts under salt and osmotic stresses. In addition, the enriched gene ontology (GO) terms for the selected tissue groups were differed, including some unique enriched GO terms such as photosynthesis and tetrapyrrole binding only in leaf tissues, while the stem-specific genes showed unique GO terms related to plant-type cell wall biogenesis, and root-specific genes showed unique GO terms such as monooxygenase activity. Furthermore, there were multiple hormone cross-talks in response to osmotic and salt stress. In summary, our multidimensional mRNA sequencing revealed tissue selective signalling and hormone crosstalk in response to salt and osmotic stresses in G. arboreum. To our knowledge, this is the first such report of spatial resolution of transcriptome analysis in G. arboreum. Our study will potentially advance understanding of possible transcriptional networks associated with water stress in cotton and other crop species.

[In vivo and in vitro research study of the influence on placenta angiogenesis by gene silencing of netrin-1].

OBJECTIVE: To study influence on angiogenesis of placenta by gene silencing of netrin-1. METHODS: Netrin-1 gene in human umbilical vein endothelial cells (HUVEC) and placenta of pregnant rats were silenced by RNA interference. The following methods were used in this study, including the phenytetrazoliumromide (MTT) for viability, clone formation for proliferation, transwell for migration, and tube formation for angiogenesis in vitro. The change of fetal growth was recorded. Placental microvessel density in pregnant rats was measured by immunohistochemical CD(34) staining in vivo. RESULTS: (1) HUVEC: viability and proliferation of HUVEC were remarkably inhibited by gene silencing of netrin-1, which number of clone formation, migration cell, tube formation were from (69 ± 6)%, 86 ± 17, 37 ± 9 decreased to (46 ± 5)%, 46 ± 13 and 17 ± 5 (P < 0.05) respectively. (2) Placenta of pregnant rats: after netrin-1 gene silenced, fetal weight were decreased from (2.39 ± 0.17) g to (2.12 ± 0.10) g (P < 0.05). Placental microvessel density was decreased from (258 ± 38)/mm(2) to (197 ± 32)/mm(2) in vivo (P < 0.05). CONCLUSIONS: Gene silencing of netrin-1 could inhibit viability, proliferation, migration, tubal formation of HUVEC and angiogenesis of placenta. Netrin-1 plays an important role in regulating angiogenesis in placenta.

Transcriptome analysis reveals salt-stress-regulated biological processes and key pathways in roots of cotton (Gossypium hirsutum L.).

High salinity is one of the main factors limiting cotton growth and productivity. The genes that regulate salt stress in TM-1 upland cotton were monitored using microarray and real-time PCR (RT-PCR) with samples taken from roots. Microarray analysis showed that 1503 probe sets were up-regulated and 1490 probe sets were down-regulated in plants exposed for 3h to 100mM NaCl, and RT-PCR analysis validated 42 relevant/related genes. The distribution of enriched gene ontology terms showed such important processes as the response to water stress and pathways of hormone metabolism and signal transduction were induced by the NaCl treatment. Some key regulatory gene families involved in abiotic and biotic sources of stress such as WRKY, ERF, and JAZ were differentially expressed. Our transcriptome analysis might provide some useful insights into salt-mediated signal transduction pathways in cotton and offer a number of candidate genes as potential markers of tolerance to salt stress.

Role of axonal guidance factor netrin-1 in human placental vascular growth.

This study investigated the role of netrin-1 in placental vascular development. In vitro rat aortic ring assay and in vivo Matrigel plug assay were conducted to exmaine the effect of netrin-1 on angiogenesis. Human placental microvascular endothelial cells (HPMECs) were isolated and cultured and their viability, migration and tubular formation were studied, in order to examine the effects of netrin-1. The results showed that netrin-1 potently stimulated neovascularization in a mouse Matrigel plug in vivo and the sprouting of endothelial cells in rat aortic rings in vitro. In addition, netrin-1 enhanced the viability, migration and tube formation of HPMECs. Our study suggested that netrin-1 could significantly promote the formation of blood vessels of human placenta and may be a potential target for developing new therapeutic strategies for placental vasculature-related diseases.

Expression of baculovirus anti-apoptotic genes p35 and op-iap in cotton (Gossypium hirsutum L.) enhances tolerance to verticillium wilt.

BACKGROUND: Programmed cell death plays an important role in mediating plant adaptive responses to the environment such as the invasion of pathogens. Verticillium wilt, caused by the necrotrophic pathogen Verticillium dahliae, is a serious vascular disease responsible for great economic losses to cotton, but the molecular mechanisms of verticillium disease and effective, safe methods of resistance to verticillium wilt remain unexplored. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we introduced baculovirus apoptosis inhibitor genes p35 and op-iap into the genome of cotton via Agrobacterium-mediated transformation and analyzed the response of transgenic plants to verticillium wilt. Results showed that p35 and op-iap constructs were stably integrated into the cotton genome, expressed in the transgenic lines, and inherited through the T(3) generation. The transgenic lines had significantly increased tolerance to verticillium wilt throughout the developmental stages. The disease index of T(1)-T(3) generation was lower than 19, significantly (P<0.05) better than the negative control line z99668. After treatment with 250 mg/L VD-toxins for 36 hours, DNA from negative control leaves was fragmented, whereas fragmentation in the transgenic leaf DNA did not occur. The percentage of cell death in transgenic lines increased by 7.11% after 60 mg/L VD-toxin treatment, which was less than that of the negative control lines's 21.27%. This indicates that p35 and op-iap gene expression partially protects cells from VD-toxin induced programmed cell death (PCD). CONCLUSION/SIGNIFICANCE: Verticillium dahliae can trigger plant cells to die through induction of a PCD mechanism involved in pathogenesis. This paper provides a potential strategy for engineering broad-spectrum necrotrophic disease resistance in plants.