Induced Response Genes Research Articles

Genome-wide analysis of polyphenol oxidase gene family in Solanum tuberosum and functional identification of StuPPO9 in regulating tolerance to Phytophthora infestans

Polyphenol oxidase (PPO) is the key enzyme involved in the enzymatic browning of potato tubers. However, the understanding of its other functions, as well as the underlying molecular mechanisms, is still limited. StuPPO9 was predicted as an inducible gene in response to disease defense and cell rescue, as analyzed using the EST database. In this study, an identification and evolutionary analysis of PPOs in Solanum tuberosum was conducted. A total of 10 members of StuPPOs were identified and their gene structure, protein motifs, chromosomal location, and tissue distribution were further investigated. QRT-PCR analysis indicated that most PPOs were induced or inhibited under hormone treatments, and StuPPO9 showed the highest expression level when induced by Phytophthora infestans. Therefore, StuPPO9, the only one located on chromosome 2, was selected for further study. The StuPPO9 overexpressing Nicotiana benthamiana transgenic line effectively slowed down the growth of P. infestans and showed more tolerance compared to the wild type (WT). Moreover, the molecular markers NtHin1 and PR genes were significantly upregulated in the transgenic tobacco than in WT under P. infestans infection. This study will provide a basis and reference for future research on the roles of StuPPO9 in disease defense.

Computation of mRNA Number Distributions in Interactive Pathway Stochastic Gene Transcription Model

Gene expression is a stochastic process characterized by fluctuations in the amount of mRNA in individual cells of an isogenic cell population. The fluctuation can be characterized by the mRNA number distribution Pm (t) , which denotes the probability of producing m copies of mRNA molecules in one cell at time t. For a given stochastic gene transcription model, how to solve the corresponding Pm (t) exact expression has been a hot research topic in this field. In the existing work, most of the results are solved for Pm (t) in the steady state case or in a specific parameter region, which affects us to fully understand the kinetic effects of different stochastic gene regulation patterns on the distribution of mRNA quantities. In this thesis, we explore the computation of Pm (t) for the cross-talk pathway model and give its exact expression under arbitrary system parameter conditions. The interactive signaling pathway model is successfully applied to elaborate stochastic transcription data of inducible genes in response to environmental changes. This work provides a kinetic theoretical basis for us to further investigate the interactive signaling pathway regulatory mechanism of gene transcription.

Tomato E8 Encodes a C-27 Hydroxylase in Metabolic Detoxification of α-Tomatine during Fruit Ripening.

Tomato (Solanum lycopersicum) contains α-tomatine, a steroidal glycoalkaloid that contributes to the plant defense against pathogens and herbivores through its bitter taste and toxicity. It accumulates at high levels in all the plant tissues, especially in leaves and immature green fruits, whereas it decreases during fruit ripening through metabolic conversion to the nontoxic esculeoside A, which accumulates in the mature red fruit. This study aimed to identify the gene encoding a C-27 hydroxylase that is a key enzyme in the metabolic conversion of α-tomatine to esculeoside A. The E8 gene, encoding a 2-oxoglutalate-dependent dioxygenase, is well known as an inducible gene in response to ethylene during fruit ripening. The recombinant E8 was found to catalyze the C-27 hydroxylation of lycoperoside C to produce prosapogenin A and is designated as Sl27DOX. The ripe fruit of E8/Sl27DOX-silenced transgenic tomato plants accumulated lycoperoside C and exhibited decreased esculeoside A levels compared with the wild-type (WT) plants. Furthermore, E8/Sl27DOX deletion in tomato accessions resulted in higher lycoperoside C levels in ripe fruits than in WT plants. Thus, E8/Sl27DOX functions as a C-27 hydroxylase of lycoperoside C in the metabolic detoxification of α-tomatine during tomato fruit ripening, and the efficient detoxification by E8/27DOX may provide an advantage in the domestication of cultivated tomatoes.

Pancreatic, but not myeloid-cell, expression of interleukin-1alpha is required for maintenance of insulin secretion and whole body glucose homeostasis

ObjectiveThe expression of the interleukin-1 receptor type I (IL-1R) is enriched in pancreatic islet β-cells, signifying that ligands activating this pathway are important for the health and function of the insulin-secreting cell. Using isolated mouse, rat, and human islets, we identified the cytokine IL-1α as a highly inducible gene in response to IL-1R activation. In addition, IL-1α is elevated in mouse and rat models of obesity and Type 2 diabetes. Since less is known about the biology of IL-1α relative to IL-1β in pancreatic tissue, our objective was to investigate the contribution of IL-1α to pancreatic β-cell function and overall glucose homeostasis in vivo. MethodsWe generated a novel mouse line with conditional IL-1α alleles and subsequently produced mice with either pancreatic- or myeloid lineage-specific deletion of IL-1α. ResultsUsing this in vivo approach, we discovered that pancreatic (IL-1αPdx1−/−), but not myeloid-cell, expression of IL-1α (IL-1αLysM−/−) was required for the maintenance of whole body glucose homeostasis in both male and female mice. Moreover, pancreatic deletion of IL-1α led to impaired glucose tolerance with no change in insulin sensitivity. This observation was consistent with our finding that glucose-stimulated insulin secretion was reduced in islets isolated from IL-1αPdx1−/− mice. Alternatively, IL-1αLysM−/− mice (male and female) did not have any detectable changes in glucose tolerance, respiratory quotient, physical activity, or food intake when compared with littermate controls. ConclusionsTaken together, we conclude that there is an important physiological role for pancreatic IL-1α to promote glucose homeostasis by supporting glucose-stimulated insulin secretion and islet β-cell mass in vivo.

REDD1 upregulation via AP‐1 alleviates oxidative stress‐mediated liver injury

Regulated in development and DNA damage responses 1 (REDD1) is an inducible gene in response to various stresses, which functions as a negative regulator of the mammalian target of rapamycin protein kinase in complex 1. In the present study, we identified the role of REDD1 under the oxidative stress‐mediated hepatocyte injury and its regulatory mechanism. REDD1 protein was increased in H2O2 or tert‐butylhydroperoxide (t‐BHP)‐treated hepatocytes· H2O2 also elevated REDD1 mRNA levels. This event was inhibited by antioxidants such as diphenyleneiodonium chloride, N‐acetyl‐L‐cysteine, or butylated hydroxy anisole. Interestingly, we found that H2O2‐mediated REDD1 induction was transcriptionally regulated by activator protein‐1 (AP‐1), and that overexpression of c‐Jun increased REDD1 protein levels and REDD1 promoter‐driven luciferase activity. Deletion of the putative AP‐1 binding site in proximal region of the human REDD1 promoter significantly abolished REDD1 transactivation by c‐Jun. A NF‐E2‐related factor 2 activator, tert‐butylhydroquinone treatment also elevated REDD1 levels, but it was independent on NF‐E2‐related factor 2 activation. Furthermore, we observed that REDD1 overexpression attenuated H2O2 or t‐BHP‐derived reactive oxygen species formation as well as cytotoxicity. Conversely, siRNA against REDD1 aggravated t‐BHP‐induced reactive oxygen species generation and cell death. In addition, we showed that REDD1 was induced by in vitro or in vivo ischemia/reperfusion model. Our results demonstrate that REDD1 induction by oxidative stress is mainly transcriptionally regulated by AP‐1, and protects oxidative stress‐mediated hepatocyte injury. These findings suggest REDD1 as a novel molecule that reduced susceptibility to oxidant‐induced liver injury.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Induction of REDD1 via AP-1 prevents oxidative stress-mediated injury in hepatocytes

Regulated in development and DNA damage responses 1 (REDD1) is an inducible gene in response to various stresses, which functions as a negative regulator of the mammalian target of rapamycin protein kinase in complex 1. In the present study, we identified the role of REDD1 under the oxidative stress-mediated hepatocyte injury and its regulatory mechanism. REDD1 protein was increased in H2O2 or tert-butylhydroperoxide (t-BHP)-treated hepatocytes· H2O2 also elevated REDD1 mRNA levels. This event was inhibited by antioxidants such as diphenyleneiodonium chloride, N-acetyl-L-cysteine, or butylated hydroxy anisole. Interestingly, we found that H2O2-mediated REDD1 induction was transcriptionally regulated by activator protein-1 (AP-1), and that overexpression of c-Jun increased REDD1 protein levels and REDD1 promoter-driven luciferase activity. Deletion of the putative AP-1 binding site in proximal region of the human REDD1 promoter significantly abolished REDD1 transactivation by c-Jun. A NF-E2-related factor 2 activator, tert-butylhydroquinone treatment also elevated REDD1 levels, but it was independent on NF-E2-related factor 2 activation. Furthermore, we observed that REDD1 overexpression attenuated H2O2 or t-BHP-derived reactive oxygen species formation as well as cytotoxicity. Conversely, siRNA against REDD1 aggravated t-BHP-induced reactive oxygen species generation and cell death. In addition, we showed that REDD1 was induced by in vitro or in vivo ischemia/reperfusion model. Our results demonstrate that REDD1 induction by oxidative stress is mainly transcriptionally regulated by AP-1, and protects oxidative stress-mediated hepatocyte injury. These findings suggest REDD1 as a novel molecule that reduced susceptibility to oxidant-induced liver injury.

Rasd1, a small G protein with a big role in the hypothalamic response to neuronal activation.

BackgroundRasd1 is a member of the Ras family of monomeric G proteins that was first identified as a dexamethasone inducible gene in the pituitary corticotroph cell line AtT20. Using microarrays we previously identified increased Rasd1 mRNA expression in the rat supraoptic nucleus (SON) and paraventricular nucleus (PVN) of the hypothalamus in response to increased plasma osmolality provoked by fluid deprivation and salt loading. RASD1 has been shown to inhibit adenylyl cyclase activity in vitro resulting in the inhibition of the cAMP-PKA-CREB signaling pathway. Therefore, we tested the hypothesis that RASD1 may inhibit cAMP stimulated gene expression in the brain.ResultsWe show that Rasd1 is expressed in vasopressin neurons of the PVN and SON, within which mRNA levels are induced by hyperosmotic cues. Dexamethasone treatment of AtT20 cells decreased forskolin stimulation of c-Fos, Nr4a1 and phosphorylated CREB expression, effects that were mimicked by overexpression of Rasd1, and inhibited by knockdown of Rasd1. These effects were dependent upon isoprenylation, as both farnesyltransferase inhibitor FTI-277 and CAAX box deletion prevented Rasd1 inhibition of cAMP-induced gene expression. Injection of lentiviral vector into rat SON expressing Rasd1 diminished, whereas CAAX mutant increased, cAMP inducible genes in response to osmotic stress.ConclusionsWe have identified two mechanisms of Rasd1 induction in the hypothalamus, one by elevated glucocorticoids in response to stress, and one in response to increased plasma osmolality resulting from osmotic stress. We propose that the abundance of RASD1 in vasopressin expressing neurons, based on its inhibitory actions on CREB phosphorylation, is an important mechanism for controlling the transcriptional responses to stressors in both the PVN and SON. These effects likely occur through modulation of cAMP-PKA-CREB signaling pathway in the brain.

Gender dependent importance of IRAK-1 in dextran sulfate sodium induced colitis

Toll-like receptor (TLR) signaling is important for the induction of pro-inflammatory cytokines and interferon (IFN)-inducible genes in response to bacterial and viral challenge. Interleukin-1 receptor-associated kinase-1 (IRAK-1) is a signaling kinase situated downstream of the adapter protein myeloid differentiation factor 88 (MyD88) in the TLR intracellular signaling cascade and is required for normal signal transduction through this pathway. We investigated the importance of IRAK-1 in intestinal inflammation by using the dextran sulfate sodium (DSS)-colitis model. We show that IRAK-1 deficient mice are protected against systemic signs of inflammation, i.e., weight loss and spleen enlargement compared to wild-type controls irrespective of gender. However, IRAK-1 −/y males but not IRAK-1 −/− females display significant protection against colitis and thymic atrophy compared to wild-type mice. Our results indicate a gender specific effect of IRAK-1 in the DSS-induced colitis, an interesting finding since the Irak-1 gene is located on the X-chromosome and several inflammatory diseases have a gender dependent incidence.

Toll-like Receptor-dependent and -independent Viperin Gene Expression and Counter-regulation by PRDI-binding Factor-1/BLIMP1

Here we identify Viperin as a highly inducible gene in response to lipopolysaccharide (LPS), double-stranded RNA (poly(I-C)) or Sendai virus (SV). The only known function of Viperin relates to its ability to inhibit human Cytomegalovirus replication. Very little data are available on the regulation of this gene. In silico analysis of the promoter identified two interferon (IFN)-stimulated response elements (ISRE), which in other genes bind IRF3 or the IFN-stimulated gene factor-3 (ISGF3) complex. LPS and poly(I-C) induce very high levels of Viperin in wild type cells but not in cells deficient in TRIF, TBK1, IRF3, or the type I IFNalpha/betaR. SV-induced Viperin gene expression was mediated independently of Toll-like receptor (TLR) signaling by retinoic acid-inducible gene (RIG-I) and the downstream adapter, mitochondrial anti-viral signaling (MAVS). Virus-induced Viperin expression was not attenuated in macrophages deficient in either TBK1 or IKKepsilon alone. Moreover, IRF3-deficient, but not IFNalpha/betaR deficient, macrophages still induced Viperin in response to SV. Promoter reporter studies combined with DNA immunoprecipitation assays identified the ISGF3 complex as the key regulator of Viperin gene expression. Moreover, positive regulatory domain I-binding factor 1 (PRDI-BF1, also called BLIMP1) binds the ISRE sites and competes with ISGF3 binding in a virus inducible manner to inhibit Viperin transcription. Collectively, these studies identify Viperin as a tightly regulated ISGF3 target gene, which is counter-regulated by PRDI-BF1.

Ekspresi Gen GFDD4-1 pada Physcomitrella patens dan Gen Homolog pada Arabidopsis thaliana dalam Respons terhadap Cekaman Abiotik

A number of abiotic stress responsive genes have been identified from various plant species through reverse genetic strategy. A group of genes are involved in plant responses to stress; they are activated by diverse stress conditions and through different mechanisms. One single gene can be induced by several different stress factors; on the other hand, a number of genes can be up-regulated by a single factor. In Physcomitrella patens , through Northern hybridization, the transcript level of the gene GFDD4-I was detected to be markedly increased by ABA, dehydration and cold, but not by salinity and osmotic stress. In Arabidopsis thaliana , a homologous gene to GFDD4-1 namely At2g47770 , was confirmed to fulfill similar function as in P. patens : it is inducible by various abiotic stress treatments, i.e. ABA, dehydration, salinity, and cold. Inducible genes in response to abiotic stress factors may be responsible for plant tolerance to those factors.

GFDD4-1 Gene Expression in Physcomitrella patens and Homologous Gene in Arabidopsis thaliana in Response to Abiotic Stress

A number of abiotic stress responsive genes have been identified from various plant species through reverse genetic strategy. A group of genes are involved in plant responses to stress; they are activated by diverse stress conditions and through different mechanisms. One single gene can be induced by several different stress factors; on the other hand, a number of genes can be up-regulated by a single factor. In Physcomitrella patens, through Northern hybridization, the transcript level of the gene GFDD4-I was detected to be markedly increased by ABA, dehydration and cold, but not by salinity and osmotic stress. In Arabidopsis thaliana, a homologous gene to GFDD4-1 namely At2g47770, was confirmed to fulfill similar function as in P. patens: it is inducible by various abiotic stress treatments, i.e. ABA, dehydration, salinity, and cold. Inducible genes in response to abiotic stress factors may be responsible for plant tolerance to those factors.

Activation of nuclear factor-kappaB in inflammatory myopathies and Duchenne muscular dystrophy.

To investigate the immunolocalization and activation of nuclear factor-kappaB (NF-kappaB) in polymyositis, dermatomyositis, and Duchenne muscular dystrophy (DMD). NF-kappaB is a major transcription factor modulating the cellular immune, inflammatory, and proliferative responses. In skeletal muscle it was demonstrated to play a role in the expression of inducible genes in response to oxidative stress and ischemia/reperfusion injury, and also in myonuclear apoptosis and muscle catabolism. Some data suggest that NF-kappaB may play a role in the pathogenesis of inclusion body myositis. Muscle samples from five patients each with polymyositis, dermatomyositis, and DMD and 10 normal controls were studied by immunocytochemistry and Western blot of nuclear extracts for the activated form of NF-kappaB. NF-kappaB DNA binding activity was studied by electrophoretic mobility shift assay (EMSA). Immunoreactivity for NF-kappaB was found in the cytoplasm of all regenerating fibers and in 20 to 40% of necrotic fibers. Western blot analysis of nuclear extracts showed a single band corresponding to 65 kd in all patients. EMSA analysis confirmed activation of NF-kappaB pathway in inflammatory myopathies and, to a lesser extent, also in DMD. These data indicate that nuclear factor-kappaB pathway is activated in polymyositis, dermatomyositis, and Duchenne muscular dystrophy. It may play a role in modulating the immune response and in regulating myogenesis and muscle repair.