CAMTA1 Research Articles

Multi-omics analysis reveals specific modifications associated with reduced chilling injury in bell pepper fruit by methyl jamonate

Bell pepper is prone to chilling injury during cold storage. In this study, the plant hormone, methyl jasmonate (MeJA), which can stimulate the expression of plant defense genes, was used to investigate its effects on the transcriptome, metabolome and proteome after 6 days at 4 ℃. Differentially expressed (DE) mRNAs that were identified with plant hormone signaling included the transcription factor MYC2, and those associated with antioxidant properties, membrane lipids and cell wall modification, fruit quality and an important transcription factors pathway -- calmodulin-binding transcription activator - c-repeat-binding factor - transcription factor ICE1 (CMAT-CaCBF1A-ICE1). Effects on the proteome analysis were mainly associated with glutathione metabolism, biosynthesis of unsaturated fatty acids and fatty acid metabolism. Differentially expressed metabolites were identified as acids, phenolics, and capsaicin. Our study suggests that MeJA treatment mitigates chilling injury of bell peppers though inhibiting the MYC2-JA signaling pathway, enhancing the ASA-GSH cycle, reducing membrane lipid damage, suppressing cell wall disassembly, and activating the CMAT-CBF-ICE pathway. These results provide a theoretical basis for further study on chilling injury of bell pepper fruit.

Evolution Analyses of CAMTA Transcription Factor in Plants and Its Enhancing Effect on Cold-tolerance.

The calmodulin binding transcription activator (CAMTA) is a transcription factor that is widely present in eukaryotes with conserved structure. It contributes to the response to biotic and abiotic stresses and promotes the growth and development of plants. Although previous studies have investigated the number and function of CAMTAs in some species, there is still a lack of comprehensive understanding of the evolutionary process, phylogenetic relationship, expression patterns, and functions of CAMTAs in plants. Here we identified 465 CMATA genes from 112 plants and systematically studied the origin of CAMTA family, gene expansion, functional differentiation, gene structure, and conservative motif distribution. Based on these analyses, we presented the evidence that CAMTA family was originated from chlorophyta, and we speculated that CAMTA might experience obvious structure variation during its early evolution, and that the number of CAMTA genes might gradually increase in higher plants. To reveal potential functions of CAMTA genes, we analyzed the expression patterns of 12 representative species and found significant species specificity, tissue specificity, and developmental stage specificity of CAMTAs. The results also indicated that the CAMTA genes might promote the maturation and senescence. The expression levels and regulatory networks of CAMTAs revealed that CAMTAs could enhance cold tolerance of rice by regulating carbohydrate metabolism-related genes to accumulate carbohydrates or by modulating target genes together with other transcription factors. Our study provides an insight into the molecular evolution of CAMTA family and lays a foundation for further study of related biological functions.

Comprehensive genome-wide analysis of calmodulin-binding transcription activator (CAMTA) in Durio zibethinus and identification of fruit ripening-associated DzCAMTAs

BackgroundFruit ripening is an intricate developmental process driven by a highly coordinated action of complex hormonal networks. Ethylene is considered as the main phytohormone that regulates the ripening of climacteric fruits. Concomitantly, several ethylene-responsive transcription factors (TFs) are pivotal components of the regulatory network underlying fruit ripening. Calmodulin-binding transcription activator (CAMTA) is one such ethylene-induced TF implicated in various stress and plant developmental processes.ResultsOur comprehensive analysis of the CAMTA gene family in Durio zibethinus (durian, Dz) identified 10 CAMTAs with conserved domains. Phylogenetic analysis of DzCAMTAs, positioned DzCAMTA3 with its tomato ortholog that has already been validated for its role in the fruit ripening process through ethylene-mediated signaling. Furthermore, the transcriptome-wide analysis revealed DzCAMTA3 and DzCAMTA8 as the highest expressing durian CAMTA genes. These two DzCAMTAs possessed a distinct ripening-associated expression pattern during post-harvest ripening in Monthong, a durian cultivar native to Thailand. The expression profiling of DzCAMTA3 and DzCAMTA8 under natural ripening conditions and ethylene-induced/delayed ripening conditions substantiated their roles as ethylene-induced transcriptional activators of ripening. Similarly, auxin-suppressed expression of DzCAMTA3 and DzCAMTA8 confirmed their responsiveness to exogenous auxin treatment in a time-dependent manner. Accordingly, we propose that DzCAMTA3 and DzCAMTA8 synergistically crosstalk with ethylene during durian fruit ripening. In contrast, DzCAMTA3 and DzCAMTA8 antagonistically with auxin could affect the post-harvest ripening process in durian. Furthermore, DzCAMTA3 and DzCAMTA8 interacting genes contain significant CAMTA recognition motifs and regulated several pivotal fruit-ripening-associated pathways.ConclusionTaken together, the present study contributes to an in-depth understanding of the structure and probable function of CAMTA genes in the post-harvest ripening of durian.

Genome-Wide Identification, Expression Profile, and Alternative Splicing Analysis of CAMTA Family Genes in Cucumber (Cucumis sativus L.)

The calmodulin-binding transcription activator (CAMTA), as one of the most distinctive families of transcription factors, plays an important role in plant growth and development and in the stress response. However, it is currently unknown whether CAMTA exists in cucumbers and what its function is. In this study, we first identified four CAMTA genes in the cucumber genome using a genome-wide search method. Subsequently, we analyzed their physical and chemical properties, gene structure, protein domains, and phylogenetic relationships. The results show that the structure of CsCAMTAs is similar to that of other plants, and a phylogenetic analysis divides them into three groups. The analysis of cis-acting elements shows that most CsCAMTAs contain a variety of hormones and stress-related elements. The RT-PCR analysis shows that CsCAMTAs have different expression levels in different tissues and can be induced by IAA, ABA, MeJA, NaCl, and PEG. Finally, we analyzed the expression pattern of CsCAMTAs’ alternative spliceosomes under salt and drought stress. The results show that the expression levels of the different spliceosomes are affected by the type of stress and the duration of stress. These data indicate that CsCAMTAs participate in growth and development and in the stress response in cucumbers, a finding which lays the foundation for future CsCAMTAs’ functional research.

A calmodulin-binding transcription factor links calcium signaling to antiviral RNAi defense in plants

RNA interference (RNAi) is an across-kingdom gene regulatory and defense mechanism. However, little is known about how organisms sense initial cues to mobilize RNAi. Here, we show that wounding to Nicotiana benthamiana cells during virus intrusion activates RNAi-related gene expression through calcium signaling. A rapid wound-induced elevation in calcium fluxes triggers calmodulin-dependent activation of calmodulin-binding transcription activator-3 (CAMTA3), which activates RNA-dependent RNA polymerase-6 and Bifunctional nuclease-2 (BN2) transcription. BN2 stabilizes mRNAs encoding key components of RNAi machinery, notably AGONAUTE1/2 and DICER-LIKE1, by degrading their cognate microRNAs. Consequently, multiple RNAi genes are primed for combating virus invasion. Calmodulin-, CAMTA3-, or BN2-knockdown/knockout plants show increased susceptibility to geminivirus, cucumovirus, and potyvirus. Notably, Geminivirus V2 protein can disrupt the calmodulin-CAMTA3 interaction to counteract RNAi defense. These findings link Ca2+ signaling to RNAi and reveal versatility of host antiviral defense and viral counter-defense.

Epigenetic Control of Foxp3, CAMTA1 and FUT7 Genes in Human Regulatory T Cells

Regulatory T cells (Treg) are essential for immune tolerance and play a key role in autoimmune diseases, allergy and cancer. Foxp3 (Forkhead Box Transcription factor), encoded on Xp11.23 chromosome, is critical for the development, function and lineage commitment of Tregs, and has been widely used as a Treg specific marker. However, human CD4+CD25+Foxp3+ T cells are heterogeneous and include resting and activated Tregs, as well as non-suppressive Treg-like cells. The ability to distinguish between these subtypes may be critical in the development of Treg-based cell therapies. CD15s (sialyl Lewis x) was identified as a highly specific marker of activated and most suppressive effector Treg (eTreg), and the use of both CD45RA and CD15s enables the isolation of several CD4+CD25+Foxp3+ T cell subtypes with diverse functional profiles.Foxp3 is mainly regulated by epigenetic processes such as histone acetylation and methylation of CpG islands. Three regions on Foxp3 locus - enhancer, promoter and CNS 2 (also known as Treg Specific Demethylated Region, TSDR) contribute to Foxp3 expression via demethylation of their CpG islands and can be used as molecular markers that distinguish Treg from conventional CD4+ T lymphocytes (Tcon) and different Treg maturation stages.In this study, we characterised the epigenetic profile of four populations of CD4+CD25+ T cells: CD45RA+ CD15s- Foxp3low (naïve nTregs), CD45RA-15s-Foxp3low (non-suppressive Treg-like cells), CD45RA-CD15s+Foxp3high (eTregs) and Tcons, and CD34+ cells, all isolated from the peripheral blood of healthy male and female donors. Methylation patterns of Foxp3 locus enhancer, promoter, pre-TSDR (located upstream of TSDR) and TSDR were investigated together with those of calmodulin binding transcription activator (CAMTA 1), and fucosyltransferase 7 (FUT 7) promoters. CAMTA 1 was previously identified as a potential second molecular marker that could differentiate Treg from Tcon as this gene is encoded on chromosome 1 and is not affected by X-chromosome inactivation. FUT 7 promoter was chosen as FUT 7 mediates synthesis of CD15s expressed in both eTregs and CD34+ cells and, therefore, it was expected to be demethylated in these cell populations to allow for protein expression.Genomic DNA, isolated from the 5 cell populations, was subjected to bisulphite conversion followed by PCR-amplification of each gene region with bisulphite DNA specific primers and cloning into pGEM-T vector. Up to 24 clones (20 sequences fully covering each amplicon) were analysed and methylation status of each CpG position within all 6 gene regions was determined. As these gene regions were amplified from the same DNA sample, the methylation differences reflect the average status of the cell population.We demonstrate the intricate methylation patterns of FUT7 and CAMTA1 promoters and Foxp3 enhancer, promoter, pre-TSDR and TSDR for 10 male and female donors. Overall, Treg cell populations from donors of both genders displayed high demethylation levels in Foxp3 promoter and TSDR while only certain CpGs (4, 9, 11, 20-30 in Foxp3 enhancer and 1, 5, 7-9 in pre-TSDR) were more demethylated in Treg subtypes compared to Tcon. CD34+, CD45RA-CD15s- Foxp3low and eTreg populations had high demethylation levels in CpGs 5-16 of FUT7 promoter (highest in CpGs 5, 8-10) compared to nTreg and Tcon, suggesting that this regulatory element can be used as an additional molecular marker to distinguish eTreg from nTreg and Tcon. CAMTA 1 promoter (especially CpGs 2 and 11) was more demethylated in CD34+ and Treg cell populations compared to Tcon, with CD45RA-CD15s- Foxp3low cells displaying the highest demethylation levels. In conclusion, the findings in this study suggest that Treg-specific epigenetic changes are evident not only in several regions of Foxp3 locus, but also in CAMTA1 and FUT7 promoters. Interestingly, certain CpG positions in these regions are consistently more demethylated in Treg subtypes, which suggests their importance in epigenetic control, most probably as part of the recognition sequence for methylation-sensitive transcription factors. DisclosuresNo relevant conflicts of interest to declare.

Genome-Wide Characterization and Expression Analysis of CAMTA Gene Family Under Salt Stress in Cucurbita moschata and Cucurbita maxima.

Cucurbita Linn. vegetables have a long history of cultivation and have been cultivated all over the world. With the increasing area of saline–alkali soil, Cucurbita Linn. is affected by salt stress, and calmodulin-binding transcription activator (CAMTA) is known for its important biological functions. Although the CAMTA gene family has been identified in several species, there is no comprehensive analysis on Cucurbita species. In this study, we analyzed the genome of Cucurbita maxima and Cucurbita moschata. Five C. moschata calmodulin-binding transcription activators (CmoCAMTAs) and six C. maxima calmodulin-binding transcription activators (CmaCAMTAs) were identified, and they were divided into three subfamilies (Subfamilies I, II, and III) based on the sequence identity of amino acids. CAMTAs from the same subfamily usually have similar exon–intron distribution and conserved domains (CG-1, TIG, IQ, and Ank_2). Chromosome localization analysis showed that CmoCAMTAs and CmaCAMTAs were unevenly distributed across four and five out of 21 chromosomes, respectively. There were a total of three duplicate gene pairs, and all of which had experienced segmental duplication events. The transcriptional profiles of CmoCAMTAs and CmaCAMTAs in roots, stems, leaves, and fruits showed that these CAMTAs have tissue specificity. Cis-acting elements analysis showed that most of CmoCAMTAs and CmaCAMTAs responded to salt stress. By analyzing the transcriptional profiles of CmoCAMTAs and CmaCAMTAs under salt stress, it was shown that both C. moschata and C. maxima shared similarities against salt tolerance and that it is likely to contribute to the development of these species. Finally, quantitative real-time polymerase chain reaction (qRT-PCR) further demonstrated the key role of CmoCAMTAs and CmaCAMTAs under salt stress. This study provided a theoretical basis for studying the function and mechanism of CAMTAs in Cucurbita Linn.

WWTR1(TAZ)-CAMTA1 gene fusion is sufficient to dysregulate YAP/TAZ signaling and drive epithelioid hemangioendothelioma tumorigenesis.

Epithelioid hemangioendothelioma (EHE) is a genetically homogenous vascular sarcoma that is a paradigm for TAZ dysregulation in cancer. EHE harbors a WWTR1(TAZ)-CAMTA1 gene fusion in >90% of cases, 45% of which have no other genetic alterations. In this study, we used a first of its kind approach to target the Wwtr1-Camta1 gene fusion to the Wwtr1 locus, to develop a conditional EHE mouse model whereby Wwtr1-Camta1 is controlled by the endogenous transcriptional regulators upon Cre activation. These mice develop EHE tumors that are indistinguishable from human EHE clinically, histologically, immunohistochemically, and genetically. Overall, these results demonstrate unequivocally that TAZ-CAMTA1 is sufficient to drive EHE formation with exquisite specificity, as no other tumor types were observed. Furthermore, we fully credential this unique EHE mouse model as a valid preclinical model for understanding the role of TAZ dysregulation in cancer formation and for testing therapies directed at TAZ-CAMTA1, TAZ, and YAP/TAZ signaling.

Comparative transcriptome analysis reveals resistant and susceptible genes in tobacco cultivars in response to infection by Phytophthora nicotianae

Phytophthora nicotianae is highly pathogenic to Solanaceous crops and is a major problem in tobacco production. The tobacco cultivar Beihart1000-1 (BH) is resistant, whereas the Xiaohuangjin 1025 (XHJ) cultivar is susceptible to infection. Here, BH and XHJ were used as models to identify resistant and susceptible genes using RNA sequencing (RNA-seq). Roots were sampled at 0, 6, 12, 24, and 60 h post infection. In total, 23,753 and 25,187 differentially expressed genes (DEGs) were identified in BH and XHJ, respectively. By mapping upregulated DEGs to the KEGG database, changes of the rich factor of “plant pathogen interaction pathway” were corresponded to the infection process. Of all the DEGs in this pathway, 38 were specifically regulated in BH. These genes included 11 disease-resistance proteins, 3 pathogenesis-related proteins, 4 RLP/RLKs, 2 CNGCs, 7 calcium-dependent protein kinases, 4 calcium-binding proteins, 1 mitogen-activated protein kinase kinase, 1 protein EDS1L, 2 WRKY transcription factors, 1 mannosyltransferase, and 1 calmodulin-like protein. By combining the analysis of reported susceptible (S) gene homologs and DEGs in XHJ, 9 S gene homologs were identified, which included 1 calmodulin-binding transcription activator, 1 cyclic nucleotide-gated ion channel, 1 protein trichome birefringence-like protein, 1 plant UBX domain-containing protein, 1 ADP-ribosylation factor GTPase-activating protein, 2 callose synthases, and 2 cellulose synthase A catalytic subunits. qRT-PCR was used to validate the RNA-seq data. The comprehensive transcriptome dataset described here, including candidate resistant and susceptible genes, will provide a valuable resource for breeding tobacco plants resistant to P. nicotianae infections.

CAMTA1, a novel antitumor gene, regulates proliferation and the cell cycle in glioma by inhibiting AKT phosphorylation

Identifying biomarkers for the early diagnosis of glioma and elucidating the molecular mechanisms underlying the development of this cancer are of considerable clinical importance. Recently, studies performing microarray profiling of genes to identify distinct gene signatures reported specific subtypes with predictive and prognostic relevance. Thus, we performed deep sequencing on a total of 26 glioma tissue samples to identify the frequently mutated of oncogenes and tumor suppressors in gliomas. A total of 2306 single-nucleotide polymorphisms (SNPs) and 2010 insertion and deletion sites (indels) were found by aligning sequencing information from 26 glioma samples with sequences from the normal human gene database (GRCh37/hg19). GSEA results suggest that an underexpressed gene, calmodulin binding transcription activator 1 (CAMTA1), participates in the cell proliferation and cell cycle regulation of glioma cells. Moreover, overexpression of CAMTA1 in glioma cells notably inhibited cell growth, migration, invasion and cell cycle and enhanced temozolomide (TMZ)-induced cell apoptosis in glioma cells, while CAMTA1 overexpression decreased the ITGA5, ITGB1, p-AKT, p-FAK, and Myc protein levels, suggesting that the signaling pathways of these proteins might be involved in the cellular functions of CAMTA1 in glioma. Moreover, overexpression of CAMTA1 attenuated the growth and tumorigenesis of glioma in vivo. In summary, we identified high-frequency mutant genes in glioma and provided an experimental basis for a novel mechanism by which CAMTA1 may serve as a tumor suppressor in glioma.

Ca2+/Calmodulin Complex Triggers CAMTA Transcriptional Machinery Under Stress in Plants: Signaling Cascade and Molecular Regulation.

Calcium (Ca2+) ion is a critical ubiquitous intracellular second messenger, acting as a lead currency for several distinct signal transduction pathways. Transient perturbations in free cytosolic Ca2+ ([Ca2+]cyt) concentrations are indispensable for the translation of signals into adaptive biological responses. The transient increase in [Ca2+]cyt levels is sensed by an array of Ca2+ sensor relay proteins such as calmodulin (CaM), eventually leading to conformational changes and activation of CaM. CaM, in a Ca2+-dependent manner, regulates several transcription factors (TFs) that are implicated in various molecular, physiological, and biochemical functions in cells. CAMTA (calmodulin-binding transcription activator) is one such member of the Ca2+-loaded CaM-dependent family of TFs. The present review focuses on Ca2+ as a second messenger, its interaction with CaM, and Ca2+/CaM-mediated CAMTA transcriptional regulation in plants. The review recapitulates the molecular and physiological functions of CAMTA in model plants and various crops, confirming its probable involvement in stress signaling pathways and overall plant development. Studying Ca2+/CaM-mediated CAMTA TF will help in answering key questions concerning signaling cascades and molecular regulation under stress conditions and plant growth, thus improving our knowledge for crop improvement.

Genome-wide identification and expression analysis of the calmodulin-binding transcription activator (CAMTA) gene family in wheat (Triticum aestivum L.)

BackgroundPlant calmodulin-binding transcription activator (CAMTA) proteins play important roles in hormone signal transduction, developmental regulation, and environmental stress tolerance. However, in wheat, the CAMTA gene family has not been systematically characterized.ResultsIn this work, 15 wheat CAMTA genes were identified using a genome-wide search method. Their chromosome location, physicochemical properties, subcellular localization, gene structure, protein domain, and promoter cis-elements were systematically analyzed. Phylogenetic analysis classified the TaCAMTA genes into three groups (groups A, B, and C), numbered 7, 6, and 2, respectively. The results showed that most TaCAMTA genes contained stress-related cis-elements. Finally, to obtain tissue-specific and stress-responsive candidates, the expression profiles of the TaCAMTAs in various tissues and under biotic and abiotic stresses were investigated. Tissue-specific expression analysis showed that all of the 15 TaCAMTA genes were expressed in multiple tissues with different expression levels, as well as under abiotic stress, the expressions of each TaCAMTA gene could respond to at least one abiotic stress. It also found that 584 genes in wheat genome were predicted to be potential target genes by CAMTA, demonstrating that CAMTA can be widely involved in plant development and growth, as well as coping with stresses.ConclusionsThis work systematically identified the CAMTA gene family in wheat at the whole-genome-wide level, providing important candidates for further functional analysis in developmental regulation and the stress response in wheat.

Phosphorylation of the CAMTA3 Transcription Factor Triggers Its Destabilization and Nuclear Export.

The Arabidopsis (Arabidopsis thaliana) calmodulin-binding transcription activator3 (CAMTA3) is a repressor of immunity-related genes but an activator of cold-induced or general stress-responsive genes in plants. Post-transcriptional or posttranslational mechanisms have been proposed to control CAMTA3 functions in different stress responses. Here, we show that treatment with the bacterial flg22 elicitor induces CAMTA3 phosphorylation, which is accompanied by its destabilization and nuclear export. Two flg22-responsive mitogen-activated protein kinases (MAPKs), MPK3 and MPK6, directly phosphorylate CAMTA3, with the phospho-sites contributing to CAMTA3 degradation and suppression of downstream target gene expression. However, the flg22-induced nuclear export and phospho-mobility shift can still be observed for the CAMTA3 phospho-null variant of the MAPK-modified sites, suggesting additional flg22-responsive kinases might be involved. Taken together, we propose that flg22-induced CAMTA3 depletion facilitates de-repression of downstream defense target genes, which involves phosphorylation, increased protein turnover, and nucleo-cytoplasmic trafficking.

1330-P: Molecular Biomarkers during Gestational Diabetes Mellitus

Background/Aim: Gestational diabetes mellitus (GDM) is associated with short- and long-term complication in both mothers and offspring. Molecular mechanisms are attracting increased interest for their potential as biomarkers for GDM that could lead to improved detection of GDM with positive effects on health outcomes. The aim of this study was to explore the potential of DNA methylation and single nucleotide polymorphisms (SNPs) to serve as molecular biomarkers for GDM in South African women. Methods: Genome-wide DNA methylation using a MethylationEPIC BeadChip Array (n=24) and gene-specific methylation of the adiponectin (ADIPOQ) gene using bisulfite pyrosequencing (n=286) were profiled in the peripheral blood of women with or without GDM. In addition, variants ADIPOQ rs266729 and rs17300539, and methylenetetrahydrofolate reductase (MTHFR) rs1801133 were quantified using quantitative real-time PCR (n=449). Results: Genome-wide methylation analysis identified 1046 differentially methylated CpG sites (associated with 939 genes), of which 148 CpG sites were hypermethylated and 898 CpG sites were hypomethylated (p<0.01). Among the top five CpG sites, one CpG mapped to the calmodulin-binding transcription activator 1 (CAMTA1) gene, which has been shown to regulate insulin production and secretion. Two CpG sites (-3410: p=0.048 and -3400: p=0.004) in the ADIPOQ promoter were hypomethylated during GDM in Human Immunodeficiency Virus (HIV) negative, but not in HIV positive women. Lastly, no association between ADIPOQ and MTHFR polymorphisms and GDM was observed in our population. Discussion: DNA methylation may offer potential as molecular biomarkers for GDM in a South African population. Future longitudinal studies in larger samples that include both HIV negative and positive pregnant women are warranted to explore the candidacy of DNA methylation as molecular biomarkers for GDM. Disclosure S. Dias: None. S. Adam: None. P. Rheeder: None. J. Louw: None. C. Pheiffer: None. Funding National Research Foundation (99391); South African Medical Research Council

Transcriptomic and proteomic profiles of II YOU 838 (Oryza sativa) provide insights into heat stress tolerance in hybrid rice

Heat stress is an increasing threat to rice production worldwide. To investigate the mechanisms of heat tolerance in hybrid rice and their contributions to rice heterosis, we compared the transcriptome of the hybrid rice II YOU 838 (II8) with the transcriptomes of its parents Fu Hui 838 (F8) and II-32A (II3) after heat stress at 42 °C for 0 h, 24 h, 72 h and 120 h. We also performed a proteomic analysis in II8 after heat stress at 42 °C for 24 h. The transcriptome data revealed time-dependent gene expression patterns under the heat stress conditions, and the heat stress response of II8 was greatly different from those of its parents. Gene ontology analysis of the differentially expressed genes that were clustered using k-means clustering showed that most of the up-regulated genes were involved in responses to stimuli, cell communication, and metabolic and transcription factor activities, whereas the down-regulated genes were enriched in photosynthesis and signal transduction. Moreover, 35 unique differentially abundant proteins, including a basic helix-loop-helix transcription factor (bHLH96), calmodulin-binding transcription activator, heat shock protein (Hsp70), and chaperonin 60 (CPN60), were detected in the proteomic analysis of II8 under heat stress. The co-regulatory analysis revealed novel genes and pathways involved in heat tolerance, namely, ferredoxin-NADP reductase, peroxidases, mitogen-activated protein kinase kinase kinase, and heat shock factor (HSF)–Hsp network. Members of the Hsp and HSF families had over-dominant expression patterns in the hybrid compared with its parents, to help maintain the higher photosynthesis and antioxidant defense systems in the hybrid. Our study suggests that the complex HSF–Hsp regulatory network contribute to the heat tolerance of the hybrid rice.

Rice CaM-binding transcription factor (OsCBT) mediates defense signaling via transcriptional reprogramming

The mutant allele of rice calmodulin-binding transcription activator OsCBT, oscbt-1, exhibits broad-spectrum resistance against rice pathogens. Previously, we reported that the strong resistance of the oscbt-1 mutant to pathogens was conferred by a constitutive upregulation of defense-related genes even under pathogen-free conditions. We also found strong induction of the hypersensitive response as a reaction to pathogen invasion. The results suggest that OsCBT acts as a negative regulator of basal resistance to pathogen attack. To identify the transcriptional network regulated by OsCBT, we compared global gene expression profiles between wild-type (WT) and oscbt-1 rice plants grown under pathogen-free conditions. The results of a 3′ tiling microarray revealed that in oscbt-1 plants, 81 genes are upregulated and 200 genes are downregulated when compared with the WT. A gene ontology analysis showed that differentially regulated genes in oscbt-1 were very closely associated with “death” GO term in a biological process category, and “catalytic activity” and “binding” GO terms in a molecular function category. A MapMan analysis indicated that the functions of these genes were associated with plant responses to biotic stress. Moreover, the results from quantitative real-time PCR in the oscbt-1 mutant showed a significant effect on the gene expression patterns of the fungal pathogen response. Our results suggested that the OsCBT regulates a rice defense response by modulating the expressions of various defense-related genes.

Peltate glandular trichomes of Colquhounia vestita harbor diterpenoid acids that contribute to plant adaptation to UV radiation and cold stresses

Plant glandular trichomes (GTs) are adaptive epidermal structures that synthesize and accumulate diverse specialized metabolites well-known as defense chemicals against biotic attacks, but their roles against abiotic challenges including UV radiation and cold climates remain largely unexplored. Colquhounia vestita Wall is a Chinese-Himalayan Lamiaceae plant with dense peltate and capitate GTs on its leaf and stem surfaces under a scanning electron microscope. Three diterpenoid acids, including a clerodane 5-epi-hardwickiic acid and two labdanes polyalthic acid and E-communic acid, were identified from the peltate GTs of C. vestita through laser microdissection coupled with UPLC-MS/MS. Under UV radiation and cold stresses, the major GT component polyalthic acid increased the biomass of Arabidopsis thaliana seedlings and decreased their malondialdehyde content. Furthermore, polyalthic acid promoted photosynthetic efficiency and the expression of genes encoding peroxidative enzymes under UV radiation, and stimulated Ca2+ elevation and the expression of calmodulin binding transcription activator gene CAMTA3 and two downstream cold-responsive genes CBF3 and RD29A under cold stress. Therefore, polyalthic acid in GTs is likely to endow the plant with enhanced tolerance to UV radiation and cold stresses, which extends the current understanding of the function of GT compounds in plant adaptation to abiotic environments.

Altered Genome-Wide DNA Methylation in Peripheral Blood of South African Women with Gestational Diabetes Mellitus.

Increasing evidence implicate altered DNA methylation in the pathophysiology of gestational diabetes mellitus (GDM). This exploratory study probed the association between GDM and peripheral blood DNA methylation patterns in South African women. Genome-wide DNA methylation profiling was conducted in women with (n = 12) or without (n = 12) GDM using the Illumina Infinium HumanMethylationEPIC BeadChip array. Functional analysis of differentially methylated genes was conducted using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. A total of 1046 CpG sites (associated with 939 genes) were differentially methylated between GDM and non-GDM groups. Enriched pathways included GDM-related pathways such as insulin resistance, glucose metabolism and inflammation. DNA methylation of the top five CpG loci showed distinct methylation patterns in GDM and non-GDM groups and was correlated with glucose concentrations. Of these, one CpG site mapped to the calmodulin-binding transcription activator 1 (CAMTA1) gene, which have been shown to regulate insulin production and secretion and may offer potential as an epigenetic biomarker in our population. Further validation using pyrosequencing and conducting longitudinal studies in large sample sizes and in different populations are required to investigate their candidacy as biomarkers of GDM.

Arabidopsis CAMTA Transcription Factors Regulate Pipecolic Acid Biosynthesis and Priming of Immunity Genes

The Arabidopsis thaliana Calmodulin-binding Transcription Activator (CAMTA) transcription factors CAMTA1, CAMTA2, and CAMTA3 (CAMTA123) serve as master regulators of salicylic acid (SA)-mediated immunity, repressing the biosynthesis of SA in healthy plants. Here, we show that CAMTA123 also repress the biosynthesis of pipecolic acid (Pip) in healthy plants. Loss of CAMTA123 function resulted in the induction of AGD2-like defense response protein 1 (ALD1), which encodes an enzyme involved in Pip biosynthesis. Induction of ALD1 resulted in the accumulation of high levels of Pip, which brought about increased levels of the SA receptor protein NPR1 without induction of NPR1 expression or requirement for an increase in SA levels. Pip-mediated induction of ALD1 and genes regulating the biosynthesis of SA—CBP60g, SARD1, PAD4, and EDS1—was largely dependent on NPR1. Furthermore, Pip-mediated increase in NPR1 protein levels was associated with priming of Pip and SA biosynthesis genes to induction by low levels of SA. Taken together, our findings expand the role for CAMTA123 in regulating key immunity genes and suggest a working model whereby loss of CAMTA123 repression leads to the induction of plant defense genes and initiation of SAR.

The miR-28-5p-CAMTA2 axis regulates colon cancer progression via Wnt/β-catenin signaling.

Colon cancer is the third most commonly diagnosed cancer with high morbidity and mortality. Calmodulin-binding transcription activator 2 (CAMTA2) belongs to the calmodulin-binding transcription activator protein family. The functional role of CAMTA2 in colon cancer development remains unclear. Our research found out that CAMTA2 was high-level expressed in colon cancer, and the upregulated CAMTA2 expression was markedly correlated with poor survival. Functional experiments showed that knockdown of CAMTA2 repressed colon cancer cell proliferation/migration in vitro and attenuated proliferation in vivo. In additional, CAMTA2 expression was controlled by miR-28-5p via posttranscriptional regulation and miR-28-5p expression was reversely correlated with CAMTA2 expression in colon cancer. Moreover, enforced miR-28-5p expression downregulated the expression of CAMTA2 significantly and the restoration of CAMTA2 expression abolished the inhibitory effect of miR-28-5p on colon cancer cell proliferation and metastasis. Mechanistically, overexpression of miR-28-5p suppressed Wnt/β-catenin signaling and the inhibitory could be partly abolished by overexpression of CAMTA2. In summary, our findings reveal that miR-28-5p/CAMTA2 axis plays a critical role in human colon cancer, which might be a promising diagnosis and therapeutic target for colon cancer treatment.