Auxin and carbohydrate control flower bud development in Anthurium andraeanum during early stage of sexual reproduction.

BACKGROUND: Flower buds of Anthurium andraeanum frequently cease to grow and abort during the early flowering stage, resulting in prolonged planting times and increased commercialization costs. Nevertheless, limited knowledge exists of the mechanism of flower development after initiation in A. andraeanum. RESULTS: In this study, the measurement of carbohydrate flow and intensity between leaves and flowers during different growth stages showed that tender leaves are strong sinks and their concomitant flowers are weak ones. This suggested that the tender leaves compete with their concomitant flower buds for carbohydrates during the early growth stages, potentially causing the abortion of the flower buds. The analysis of transcriptomic differentially expressed genes suggested that genes related to sucrose metabolism and auxin response play an important role during flower bud development. Particularly, co-expression network analysis found that AaSPL12 is a hub gene engaged in flower development by collaborating carbohydrate and auxin signals. Yeast Two Hybrid assays revealed that AaSPL12 can interact with AaARP, a protein that serves as an indicator of dormancy. Additionally, the application of exogenous IAA and sucrose can suppress the expression of AaARP, augment the transcriptional abundance of AaSPL12, and consequently expedite flower development in Anthurium andraeanum. CONCLUSIONS: Collectively, our findings indicated that the combination of auxin and sugar signals could potentially suppress the repression of AaARP protein to AaSPL12, thus advancing the development of flower buds in Anthurium andraeanum.

LncRNA THEMIS2-211, a tumor-originated circulating exosomal biomarker, promotes the growth and metastasis of hepatocellular carcinoma by functioning as a competing endogenous RNA.

Hepatocellular carcinoma (HCC) is a major challenge for human health. Finding reliable diagnostic biomarkers and therapeutic targets for HCC is highly desired in the clinic. Currently, circulating exosomal lncRNA is a promising biomarker for the diagnosis of cancer and lncRNA is also a potential target in cancer therapy. Here, the diagnostic value of a panel based on exosomal lncRNA THEMIS2-211 and PRKACA-202, superior to that of AFP, was identified for diagnosing human HCC. Besides, the performance of exosomal lncRNA THEMIS2-211 alone exceeds that of AFP in diagnosing early-stage HCC patients (stage I). Furthermore, lncRNA THEMIS2-211 is highly expressed in HCC tissues and correlated with the poor prognosis of HCC patients. LncRNA THEMIS2-211 is upregulated and localized in the cytoplasm of HCC cells. LncRNA THEMIS2-211 exerts its biological function as an oncogene that promotes the proliferation, migration, invasion, EMT of HCC cells by physically interacting with miR-940 and therefore promoting SPOCK1 expressions. Rescue assays show the regulation of SPOCK1 by lncRNA THEMIS2-211 dependents on miR-940. The discovery of lncRNA THEMIS2-211 further illuminates the molecular pathogenesis of HCC and the THEMIS2-211/miR-940/SPOCK1 axis may act as a potential therapeutic target for HCC.

A conservative pathway for coordination of cell wall biosynthesis and cell cycle progression in plants.

The mechanism that coordinates cell growth and cell cycle progression remains poorly understood; in particular, whether the cell cycle and cell wall biosynthesis are coordinated remains unclear. Recently, cell wall biosynthesis and cell cycle progression were reported to respond to wounding. Nonetheless, no genes are reported to synchronize the biosynthesis of the cell wall and the cell cycle. Here, we report that wounding induces the expression of genes associated with cell wall biosynthesis and the cell cycle, and that two genes, AtMYB46 in Arabidopsis thaliana and RrMYB18 in Rosa rugosa, are induced by wounding. We found that AtMYB46 and RrMYB18 promote the biosynthesis of the cell wall by upregulating the expression of cell wall-associated genes, and that both of them also upregulate the expression of a battery of genes associated with cell cycle progression. Ultimately, this response leads to the development of curled leaves of reduced size. We also found that the coordination of cell wall biosynthesis and cell cycle progression by AtMYB46 and RrMYB18 is evolutionarily conservative in multiple species. In accordance with wounding promoting cell regeneration by regulating the cell cycle, these findings also provide novel insight into the coordination between cell growth and cell cycle progression and a method for producing miniature plants.

miR156/157 Targets SPLs to Regulate Flowering Transition, Plant Architecture and Flower Organ Size in Petunia.

miR156/157 plays multiple pivotal roles during plant growth and development. In this study, we identified 11 miR156- and 5 miR157-encoding loci from the genome of Petunia axillaris and Petunia inflata, designated as PaMIR0156/157s and PiMIR0156/157s, respectively. Real-time quantitative reverse transcription PCR (qRT-PCR) analysis indicated that PhmiR156/157 was expressed predominantly in cotyledons, germinating seeds, flower buds, young fruits and seedlings. PhmiR156/157 levels declined in shoot apical buds and leaves of petunia before flowering as the plant ages; moreover, the temporal expression patterns of most miR156/157-targeted PhSPLs were complementary to that of PhmiR156/157. Ectopic expression of PhMIR0157a in Arabidopsis and petunia resulted in delayed flowering, dwarf plant stature, increased branches and reduced organ size. However, PhMIR0156f-overexpressing Arabidopsis and petunia plants showed only delayed flowering. In addition, downregulation of PhmiR156/157 level by overexpressing STTM156/157 led to taller plants with less branches, longer internodes and precocious flowering. qRT-PCR analysis indicated that PhmiR156/157 modulates these traits mainly by downregulating their PhSPL targets and subsequently decreasing the expression of flowering regulatory genes. Our results demonstrate that the PhmiR156/157-PhSPL module has conserved but also divergent functions in growth and development, which will help us decipher the genetic basis for the improvement of flower transition, plant architecture and organ development in petunia.

RrMYB5- and RrMYB10-regulated flavonoid biosynthesis plays a pivotal role in feedback loop responding to wounding and oxidation in Rosa rugosa.

Flavonoids play critical roles in plant responses to various stresses. Few studies have been reported on what the mechanism of activating flavonoid biosynthesis in plant responses to wounding and oxidation is. In this study, flavonoid metabolites and many MYB transcript factors from Rosa rugosa were verified to be induced by wounding and oxidation. RrMYB5 and RrMYB10, which belong to PA1- and TT2-type MYB TFs, respectively, showed extremely high induction. Overexpression of RrMYB5 and RrMYB10 resulted in an increased accumulation of proanthocyanidins in R. rugosa and tobacco by promoting the expression of flavonoid structural genes. Transcriptomic analysis of the transgenic plants showed that most genes, involved in wounding and oxidation response and ABA signalling modulation, were up-regulated by the overexpression of RrMYB10, which was very much similar to that observed in RrANR and RrDFR overexpression transgenics. RrMYB5 and RrMYB10 physically interacted and mutually activated each other's expressions. They solely or synergistically activated the different sets of flavonoid pathway genes in a bHLH TF EGL3-independent manner. Eventually, the accumulation of proanthocyanidins enhanced plant tolerance to wounding and oxidative stresses. Therefore, RrMYB5 and RrMYB10 regulated flavonoid synthesis in feedback loop responding to wounding and oxidation in R. rugosa. Our study provides new insights into the regulatory mechanisms of flavonoid biosynthesis by MYB TFs and their essential physiological functions in plant responses to wounding and oxidative stresses.

Homeostatic regulation of flavonoid and lignin biosynthesis in phenylpropanoid pathway of transgenic tobacco.

Flavonoids and lignin consist of a large number of secondarymetabolites which are derived from the phenylpropanoid pathway, and they act as a significant role in plant growth, development, and stress response. However, few reports have documented that how different subbranches of phenylpropanoid metablolic pathway mutually interact. In Arabidopsis, AtCPC (AtCAPRICE) is known to play a negative role in anthocyanin accumulation. Nonetheless, whether AtCPC could control the biosynthesis of lignin is largely unknown. Additionally, whether the RrFLS and RrANR, flavonol synthase and anthocyanidin reductase, from Rosa rugosa regulate different branches of phenylpropanoid pathway is unclear. Here, we performed a series of transgenic experiments with short life cycle tobacco and RNA-Seq analysis. Finally, a series of assays related to biological, physiological, and phenotypic characteristics were undertaken. Our results indicated that ectopic expression of AtCPC in tobacco not only decreased the flavonoid compound accumulation, but also up-regulated several lignin biosynthetic genes, and significantly increased the accumulation of lignin. Our results also revealed that although they respectively improved the flavonol and proanthocyanidin contents, the overexpression of RrFLS and RrANR plays positive roles in lignin biosynthesis in transgenic tobacco plants. Our findings provide a novel insight into the mechanism underlying homeostatic regulation of flavonoid and lignin biosynthesis in phenylpropanoid pathway of plants.

CircRNA-Mediated Regulation of Angiogenesis: A New Chapter in Cancer Biology.

Angiogenesis is necessary for carcinoma progression and is regulated by a variety of pro- and anti-angiogenesis factors. CircRNAs are RNA molecules that do not have a 5'-cap or a 3'-polyA tail and are involved in a variety of biological functions. While circRNA-mediated regulation of tumor angiogenesis has received much attention, the detailed biological regulatory mechanism remains unclear. In this review, we investigated circRNAs in tumor angiogenesis from multiple perspectives, including its upstream and downstream factors. We believe that circRNAs have natural advantages and great potential for the diagnosis and treatment of tumors, which deserves further exploration.

Functional characterization of class I SlHSP17.7 gene responsible for tomato cold-stress tolerance.

Small heat shock proteins (sHSPs) increase stress tolerance in a wide variety of organisms and enable them to endure changes in their environment. However, the molecular mechanism by which sHSPs protect plants against cold stress is unknown. Here, the sHSP of tomato named SlHSP17.7 (Solyc06g076540.1.1) has the characteristic of low temperature induced expression in BL21(DE3) E. coli and a molecular chaperone function in vitro. Overexpression of SlHSP17.7 showed a tolerant response to cold stress treatment due to an induce intracellular sucrose and less accumulation of ROS. Yeast two-hybrid assays showed that SlHSP17.7 is a binding partner of the cation/Ca2+ exchanger (SlCCX1-like; Solyc07g006370.1.1). This interaction was confirmed by pull down and bimolecular fluorescence complementation (BiFC) assays. High SlHSP17.7 and low SlCCX1-like levels alleviated programed cell death (PCD) under cold stress. Thus, SlHSP17.7 might be a cofactor of SlCCX1-like targeting endoplasmic reticulum (ER) membrane proteins, retaining intracellular Ca2+ homeostasis, and decreasing cold stress sensitivity. These findings provide a sound basis for genetic engineering of cold stress tolerance in tomato.

Construction of a potential microRNA, transcription factor and mRNA regulatory network in hepatocellular carcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide and the third leading cause of cancer-related death. MicroRNAs and transcription factors (TFs) cooperate to regulate the same target gene, thus affecting the progression of HCC. METHODS: Differentially expressed miRNAs and mRNAs were screened. Functional enrichment analysis of these HCC-related mRNAs was performed, and a protein-protein interaction network was constructed. TFs that regulate these miRNAs and hub genes were also screened. RESULTS: Ten differentially upregulated miRNAs and 5 differentially downregulated miRNAs were screened. Additionally, 183 downregulated mRNAs and 303 upregulated mRNAs that are potentially bound to these differentially expressed miRNAs were identified. The Kyoto Encyclopedia of Genes and Genomes (KEGG) results showed that the differentially expressed mRNAs were significantly enriched in pathways in cancer, the Wnt signaling pathway, and the Rap1 signaling pathway. Then, 220 TFs were identified for 5 candidate genes of the downregulated mRNAs, and 258 TFs were identified for 9 candidate genes of the upregulated mRNAs. Finally, the 9 upregulated hub genes were related to higher overall survival (OS) in the low-expression group, and 4/5 downregulated hub genes were related to higher OS in the high-expression group. CONCLUSIONS: This study constructed a potential regulatory network between candidate molecules and that need to be further verified. These regulatory relationships are expected to clarify the new molecular mechanisms of the occurrence and development of HCC.

Activation of small heat shock protein (SlHSP17.7) gene by cell wall invertase inhibitor (SlCIF1) gene involved in sugar metabolism in tomato.

Fruit quality formation involves a series of physiological and biochemical changes during fruit ripening. Sucrose metabolism plays not only important roles in fruit ripening to establish energy status and nutritional quality but also a non-nutritive role in gene expression. In carbon metabolism and fruit ripening, cell wall invertases (CWINs) perform essential regulatory functions. Knowledge regarding the gene expression changes that occur following the repression of CWIN activity in fruit through the overexpression of a cell-wall inhibitor of ß-fructosidase (CIF) under a fruit-specific promoter is limited. To further explore the molecular mechanism of sucrose regulation, global expression profiling of the fruits of transgenic tomato (Solanum lycopersicum) plants carrying a cell wall invertase inhibitor (SlCIF1) gene was performed using a microarray. In total, 622 and 833 differentially expressed genes (DEGs) were identified. The expression of the SlHSP17.7 gene was increased by thousands of times in the transgenic-SlCIF1 tomato. Then, SlHSP17.7-RNA interference (RNAi) lines were generated by introducing pB7GWIWG2 (I)-SlHSP17.7 into wild-type chmielewskii tomatoes (WT). The sucrose and fructose contents significantly decreased in the RNAi fruits compared with those in the WT. Furthermore, 14 sugar metabolism related genes were also decreased synergistically by silencing SlHSP17.7 gene. Our data indicate that the posttranslational modulation of CWIN activity by SlCIF1 contributes to earlier bloom times. SlHSP17.7 and sugar can interact to regulate the development of tomato fruit and affect the quality of tomato, providing a different insight into improving the quality of tomato.

Response of linear and cyclic electron flux to moderate high temperature and high light stress in tomato.

OBJECTIVE: To evaluate the possible photoprotection mechanisms of cyclic and linear electron flux (CEF and LEF) under specific high temperature and high light (HH) stress. METHODS: Six-leaf-stage tomato seedlings ("Liaoyuanduoli", n=160) were divided into four parts: Part 1, served as control under 25 °C, 500 µmol/(m2·s); Part 2, spayed with distilled water (H2O) under 35 °C, 1000 µmol/(m2·s) (HH); Part 3, spayed with 100 µmol/L diuron (DCMU, CEF inhibitor) under HH; Part 4, spayed with 60 µmol/L methyl viologen (MV, LEF inhibitor) under HH. Energy conversion, photosystem I (PSI), and PSII activity, and trans-thylakoid membrane proton motive force were monitored during the treatment of 5 d and of the recovering 10 d. RESULTS: HH decreased photochemical reaction dissipation (P) and the maximal photochemical efficiency of PSII (Fv/Fm), and increased the excitation energy distribution coefficient of PSII (ß); DCMU and MV aggravated the partition imbalance of the excitation energy (γ) and the photoinhibition degree. With prolonged DCMU treatment time, electron transport rate and quantum efficiency of PSI (ETRI and YI) significantly decreased whereas acceptor and donor side limitation of PSI (YNA and YND) increased. MV led to a significant decline and accession of yield of regulated and non-regulated energy YNPQ and YNO, respectively. Membrane integrity and ATPase activity were reduced by HH stress, and DCMU and MV enhanced inhibitory actions. CONCLUSIONS: The protective effects of CEF and LEF were mediated to a certain degree by meliorations in energy absorption and distribution as well as by maintenance of thylakoid membrane integrity and ATPase activity.