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Plant hormones are small regulatory molecules that exert pharmacological actions in mammalian cells such as anti-oxidative and pro-metabolic effects. Kinetin belongs to the group of plant hormones cytokinin and has been associated with modulatory functions in mammalian cells. The mammalian adenosine receptor (A2a-R) is known to modulate multiple physiological responses in animal cells. Here, we describe that kinetin binds to the adenosine receptor (A2a-R) through the Asn253 residue in an adenosine dependent manner. To harness the beneficial effects of kinetin for future human use, we assess its acute toxicity by analyzing different biochemical and histological markers in rats. Kinetin at a dose below 1 mg/kg had no adverse effects on the serum level of glucose or on the activity of serum alanine transaminase (ALT) or aspartate aminotransferase (AST) enzymes in the kinetin treated rats. Whereas, creatinine levels increased after a kinetin treatment at a dose of 0.5 mg/kg. Furthermore, 5 mg/kg treated kinetin rats showed normal renal corpuscles, but a mild degeneration was observed in the renal glomeruli and renal tubules, as well as few degenerated hepatocytes were also observed in the liver. Kinetin doses below 5 mg/kg did not show any localized toxicity in the liver and kidney tissues. In addition to unraveling the binding interaction between kinetin and A2a-R, our findings suggest safe dose limits for the future use of kinetin as a therapeutic and modulatory agent against various pathophysiological conditions.
Synthetically designed alternative photorespiratory pathways increase the biomass of tobacco and rice plants. Likewise, some in planta–tested synthetic carbon-concentrating cycles (CCCs) hold promise to increase plant biomass while diminishing atmospheric carbon dioxide burden. Taking these individual contributions into account, we hypothesize that the integration of bypasses and CCCs will further increase plant productivity. To test this in silico, we reconstructed a metabolic model by integrating photorespiration and photosynthesis with the synthetically designed alternative pathway 3 (AP3) enzymes and transporters. We calculated fluxes of the native plant system and those of AP3 combined with the inhibition of the glycolate/glycerate transporter by using the YANAsquare package. The activity values corresponding to each enzyme in photosynthesis, photorespiration, and for synthetically designed alternative pathways were estimated. Next, we modeled the effect of the crotonyl-CoA/ethylmalonyl-CoA/hydroxybutyryl-CoA cycle (CETCH), which is a set of natural and synthetically designed enzymes that fix CO₂ manifold more than the native Calvin–Benson–Bassham (CBB) cycle. We compared estimated fluxes across various pathways in the native model and under an introduced CETCH cycle. Moreover, we combined CETCH and AP3-w/plgg1RNAi, and calculated the fluxes. We anticipate higher carbon dioxide–harvesting potential in plants with an AP3 bypass and CETCH–AP3 combination. We discuss the in vivo implementation of these strategies for the improvement of C3 plants and in natural high carbon harvesters.
Indoor house dust is a blend of organic and inorganic materials, upon which diverse microbial communities such as viruses, bacteria and fungi reside. Adequate moisture in the indoor environment helps microbial communities multiply fast. The outdoor air and materials that are brought into the buildings by airflow, sandstorms, animals pets and house occupants endow the indoor dust particles with extra features that impact human health. Assessment of the health effects of indoor dust particles, the type of indoor microbial inoculants and the secreted enzymes by indoor insects as allergens merit detailed investigation. Here, we discuss the applications of next generation sequencing (NGS) technology which is used to assess microbial diversity and abundance of the indoor dust environments. Likewise, the applications of NGS are discussed to monitor the gene expression profiles of indoor human occupants or their surrogate cellular models when exposed to aqueous solution of collected indoor dust samples. We also highlight the detection methods of dust allergens and analytical procedures that quantify the chemical nature of indoor particulate matter with a potential impact on human health. Our review is thus unique in advocating the applications of interdisciplinary approaches that comprehensively assess the health effects due to bad air quality in built environments.
Intricate mechanisms discriminate between friends and foes in plants. Plant organs deploy overlapping and distinct protection strategies. Despite vulnerability to a plethora of pathogens, the growing tips of plants grow bacteria free. The shoot apical meristem (SAM) is among three stem cells niches, a self-renewable reservoir for the future organogenesis of leaf, stem, and flowers. How plants safeguard this high value growth target from infections was not known until now. Recent reports find the stem cell secreted 12-amino acid peptide CLV3p (CLAVATA3 peptide) is perceived by FLS2 (FLAGELLIN SENSING 2) receptor and activates the transcription of immunity and defense marker genes. No infection in the SAM of wild type plants and bacterial infection in clv3 and fls2 mutants illustrate this natural protection against infections. Cytokinins (CKs) are enriched in the SAM and regulate meristem activities by their involvement in stem cell signaling networks. Auxin mediates plant susceptibility to pathogen infections while CKs boost plant immunity. Here, in addition to the stem-cell-triggered immunity we also highlight a potential link between CK signaling and CLV3p mediated immune response in the SAM.
Metabolism and signaling of cytokinins was first established in plants, followed by cytokinin discoveries in all kingdoms of life. However, understanding of their role in mammalian cells is still scarce. Kinetin is a cytokinin that mitigates the effects of oxidative stress in mammalian cells. The effective concentrations of exogenously applied kinetin in invoking various cellular responses are not well standardized. Likewise, the metabolism of kinetin and its cellular targets within the mammalian cells are still not well studied. Applying vitality tests as well as comet assays under normal and hyper-oxidative states, our analysis suggests that kinetin concentrations of 500 nM and above cause cytotoxicity as well as genotoxicity in various cell types. However, concentrations below 100 nM do not cause any toxicity, rather in this range kinetin counteracts oxidative burst and cytotoxicity. We focus here on these effects. To get insights into the cellular targets of kinetin mediating these pro-survival functions and protective effects we applied structural and computational approaches on two previously testified targets for these effects. Our analysis deciphers vital residues in adenine phosphoribosyltransferase (APRT) and adenosine receptor (A2A-R) that facilitate the binding of kinetin to these two important human cellular proteins. We finally discuss how the therapeutic potential of kinetin against oxidative stress helps in various pathophysiological conditions.
The growing tips of plants grow sterile; therefore, disease-free plants can be generated from them. How plants safeguard growing apices from pathogen infection is still a mystery. The shoot apical meristem (SAM) is one of the three stem cells niches that give rise to the above ground plant organs. This is very well explored; however, how signaling networks orchestrate immune responses against pathogen infections in the SAM remains unclear. To reconstruct a transcriptional framework of the differentially expressed genes (DEGs) pertaining to various SAM cellular populations, we acquired large-scale transcriptome datasets from the public repository Gene Expression Omnibus (GEO). We identify here distinct sets of genes for various SAM cellular populations that are enriched in immune functions, such as immune defense, pathogen infection, biotic stress, and response to salicylic acid and jasmonic acid and their biosynthetic pathways in the SAM. We further linked those immune genes to their respective proteins and identify interactions among them by mapping a transcriptome-guided SAM-interactome. Furthermore, we compared stem-cells regulated transcriptome with innate immune responses in plants showing transcriptional separation among their DEGs in Arabidopsis. Besides unleashing a repertoire of immune-related genes in the SAM, our analysis provides a SAM-interactome that will help the community in designing functional experiments to study the specific defense dynamics of the SAM-cellular populations. Moreover, our study promotes the essence of large-scale omics data re-analysis, allowing a fresh look at the SAM-cellular transcriptome repurposing data-sets for new questions.
Plant hormones involving salicylic acid (SA), jasmonic acid (JA), ethylene (Et), and auxin, gibberellins, and abscisic acid (ABA) are known to regulate host immune responses. However, plant hormone cytokinin has the potential to modulate defense signaling including SA and JA. It promotes plant pathogen and herbivore resistance; underlying mechanisms are still unknown. Using systems biology approaches, we unravel hub points of immune interaction mediated by cytokinin signaling in Arabidopsis. High-confidence Arabidopsis protein-protein interactions (PPI) are coupled to changes in cytokinin-mediated gene expression. Nodes of the cellular interactome that are enriched in immune functions also reconstitute sub-networks. Topological analyses and their specific immunological relevance lead to the identification of functional hubs in cellular interactome. We discuss our identified immune hubs in light of an emerging model of cytokinin-mediated immune defense against pathogen infection in plants.
Phytohormones are known for their pivotal roles in promoting normal growth and development of the plants and contributing to the mechanism of defense. Although an over simplification, however, they may be categorized as stress specific and growth promoting. SA and JA/Ethylene are implicated in stress responses while auxins, cytokinins and gibberellins are involved in developmental processes. Phytohormones from the above perspective got much attention in the last few decades; however their reciprocal role is currently in focus. It is because of the reason that plant pathogens cause overall hormonal imbalance at host pathogen interface and alter host physiology for the sake of pathogenecity. Despite their importance in growth and development, cytokinins are among the most neglected phytohormones that are usually noticed as consequence rather than a cause of pathogen infection. Results presented in this thesis are based on the hypothesis that elevated levels of CKs embody plants with resistance against hemibiotrophic pathogens. To explore a connection between the spread of P. syringae and its tobacco host, CKs over producing transgenic plants were investigated whereby bacterial IPT gene was expressed under the control of pathogen inducible, tetracycline inducible and developmentally inducible promoters. To further validate the out-come of transgenic plants, various types of cytokinins were exogenously fed to detached tobacco leaves. Mentioned transgenics and exogenous CKs feeding approaches unanimously resulted in, “more cytokinins less disease symptoms” and vice versa. This state of cytokinins mediated resistance was further substantiated with various cellular, signaling, biochemical and microbial approaches wherein levels of SA and JA remained unaffected. Conversely, PR1 gene expression was strongly up-regulated in enhanced cytokinins accumulating samples. Moreover, less accumulation of ROS was observed in IPT expressing sites of the plants as compared to their corresponding controls. Additionally, we neither noticed any direct effect of cytokinins on the growth of P. syringae pv. tabaci nor found presence of anti-microbial peptides in cytokinins enriched extracts. Interestingly, enhanced accumulation of phtyoalexins in elevated CKs status of the plant proved to be a possible gesture in jeopardizing the spread of pathogen. Contrarily, no reduction was observed in the spread of fungal necrotrophic pathogen Sclerotinia sclerotiorum when leaves of elevated CKs were inoculated. Besides host-pathogen interaction in perspective of elevated cytokinins, impact of modulated sugar status of the plant on the spread of pathogen was also investigated. For this purpose, previously generated modulated invertase enzyme tobacco transgenic plants were analyzed. We showed that repression and de-repression of CIN1 gene under the control of tetracycline inducible-promoter did not affect the growth of P. syrinage pv. tabaci in Tet::CIN1 transgenic plants. Moreover, invertase inhibitor tobacco lines expressing NtCIF gene under the control of the same promoter failed to exhibit differential pathogenic responses in induced and non induced status of the plant. Similar was the case of tomato transgenic plants expressing NtCIF gene under the control of invertase gene Lin6 promoter in Lin6:: NtCIF plants for P.syringae pv. tomato DC 3000. Interestingly, when challenged Lin6:: NtCIF tomato plants with Botrytis cinerea, severe disease symptoms were observed on transgenic leaves as compared to control plants. To dissect a potential link between cytokinins and sugar metabolism with its effect on the growth of pathogen, invertase transgenic plants with elevated CKs were probed. When expressed exogenous IPT gene under the control of pathogen inducible promoter (4xJERE::IPT) in transgenic background of Tet::CIN1, we observed localized differences in symptom development for P.syringae pv. tabaci. Similarly, when exogenously fed with kinetin, detached leaves of Tet::CIN1 exhibited retarded growth of P.syringae pv. tabaci as compared to the tetracycline induced leaves. These results led to the conclusion that extracellular invertase may not play an essential role in cytokinins mediated disease resistance against hemibiotrophic pathogens.
DNA methylation acts as a major epigenetic modification in mammals, characterized by the transfer of a methyl group to a cytosine. DNA methylation plays a pivotal role in regulating normal development, and misregulation in cells leads to an abnormal phenotype as is seen in several cancers. Any mutations or expression anomalies of genes encoding regulators of DNA methylation may lead to abnormal expression of critical molecules. A comprehensive genomic study encompassing all the genes related to DNA methylation regulation in relation to breast cancer is lacking. We used genomic and transcriptomic datasets from the Cancer Genome Atlas (TGCA) Pan-Cancer Atlas, Genotype-Tissue Expression (GTEx) and microarray platforms and conducted in silico analysis of all the genes related to DNA methylation with respect to writing, reading and erasing this epigenetic mark. Analysis of mutations was conducted using cBioportal, while Xena and KMPlot were utilized for expression changes and patient survival, respectively. Our study identified multiple mutations in the genes encoding regulators of DNA methylation. The expression profiling of these showed significant differences between normal and disease tissues. Moreover, deregulated expression of some of the genes, namely DNMT3B, MBD1, MBD6, BAZ2B, ZBTB38, KLF4, TET2 and TDG, was correlated with patient prognosis. The current study, to our best knowledge, is the first to provide a comprehensive molecular and genetic profile of DNA methylation machinery genes in breast cancer and identifies DNA methylation machinery as an important determinant of the disease progression. The findings of this study will advance our understanding of the etiology of the disease and may serve to identify alternative targets for novel therapeutic strategies in cancer.