Construction and verification of a histone deacetylases-related prognostic signature model for colon cancer.

Histone deacetylases (HDACs) contribute significantly to the initiation, progression, and prognosis of colorectal adenocarcinoma (COAD). Additionally, HDACs regulate the tumor microenvironment, immune escape, and tumor stem cells, and are closely linked to COAD prognosis. We developed a prognostic model for COAD that incorporates HDACs to evaluate their specific roles. The COAD dataset containing clinical and mutation data was collected using the TCGA and GEO databases to obtain genes associated with HDAC. LASSO analysis and univariate and multivariate Cox regression analysis were used to determine the presence of prognostic genes. Multivariate Cox analysis was also used to determine risk scores for HDAC-related features. Furthermore, genomic alterations, immune infiltration, and drug response were compared between high- and low-risk groups. Cellular experiments validated the potential regulatory role of BRD3 on COAD proliferation, migration, and apoptosis. The median risk scores, calculated based on the characteristics, demonstrated a more significant prognostic improvement in patients in the low-risk group. Furthermore, HDAC-related features were identified as important independent prognostic factors for patients with COAD. Additionally, genomic mutation status, immune infiltration, and function, as well as response to immunotherapy and chemotherapy, were found to be associated with risk scores. Subgroup analyses indicate that anti-PD-1 therapy may be beneficial for patients in the low-risk group. Additionally, a decrease in risk score was associated with a decrease in immune infiltration. Finally, HCT116 and HT29 cells exhibited inhibition of BRD3 gene proliferation and migration, as well as promotion of apoptosis. In patients with COAD, HDAC-related characteristics may be useful in predicting survival and selecting treatment.

Efficacy and safety of Xian-Lian-Jie-Du optimization decoction as an adjuvant treatment for prevention of recurrence in patients with stage IIIB/IIIC colon cancer: study protocol for a multicentre, randomized controlled trial.

INTRODUCTION: Colon cancer remains one of the most prevalent cancers worldwide. Unfortunately, there are no recognized and effective therapeutic strategies to prevent tumor recurrence after radical resection and chemotherapy, and the disease-free survival (DFS) in patients with stage IIIB or IIIC disease remains unsatisfactory. Xian-Lian-Jie-Du optimization decoction (XLJDOD) is a Chinese herbal medicine (CHM) empirical prescription, which has been validated experimentally and clinically that could inhibit the progression of colorectal cancer and ameliorate the symptoms. The purpose of this study is to evaluate the efficacy and safety of XLJDOD in prevention of recurrence of colon cancer. METHODS: This study is a multi-center, double-blind, randomized, placebo-controlled trial conducted at 13 hospitals of China. Following the completion of surgery and adjuvant 5- fluorouracil-based chemotherapy, a total of 730 subjects with stage IIIB or IIIC colon cancer will be randomized in a 1:1 ratio to an intervention group (n = 365; XLJDOD compound granule) and a control group (n = 365; Placebo). Patients will receive 6-month treatments and be followed up with 3 monthly assessments for 2 years. The primary outcome is 2-year DFS rate and the secondary outcomes are 1, 2-year relapse rate (RR), overall survival (OS) and quality of life (QoL). Safety outcomes such as adverse events will be also assessed. A small number of subgroup analysis will be carried out to explore the heterogeneity of effects of XLJDOD. DISCUSSION: The outcomes from this randomized controlled trial will provide objective evidences to evaluate XLJDOD's role as an adjuvant treatment in colon cancer. TRIAL REGISTRATION: www. CLINICALTRIALS: gov , identifier: NCT05709249. Registered on 31 Jan 2023.

Correlation between Tumor Microenvironment and Immune Subtypes Based on CD8 T Cells Enhancing Personalized Therapy of Gastric Cancer.

Background: Immunotherapy is a promising therapy for metastatic gastric cancer (GC) patients. However, the component of tumor microenvironment (TME) is a pivotal factor hindering immunotherapy outcome. CD8 T cells suppress tumor progression. This study developed an immune subtyping system and a prognostic model for guiding personalized therapy of GC patients. Methods: Marker genes related to CD8 T cells were identified by weighted correlation network analysis (WGCNA). Consensus clustering was used to develop immune subtypes. Univariate Cox regression analysis was performed to screen prognostic genes. Functional analysis (KEGG and GO annotation) and gene set enrichment analysis were applied. Results: Based on marker genes related to CD8 T cells, we identified three immune subtypes (IC1, IC2, and IC3) with distinct prognosis and differential TME. In IC3, CD8 T cell function was impaired by high activation of CXCR4/CXCL12 axis, and impaired T cell function predicted high response to immune checkpoint blockade. IC1 was sensitive to chemotherapeutic drugs but showed low response to immunotherapy. We also developed an 8-gene prognostic signature with robust performance to stratify GC patients into high-risk and low-risk groups. Conclusions: This study identified three immune subtypes and a prognostic signature, and both were effective in direct personalized therapy for GC patients. The correlation between TME and immunotherapy was further characterized from a new perspective.

A new adenylyl cyclase, putative disease-resistance RPP13-like protein 3, participates in abscisic acid-mediated resistance to heat stress in maize.

In plants, 3´,5´-cyclic adenosine monophosphate (cAMP) is an important second messenger with varied functions; however, only a few adenylyl cyclases (ACs) that synthesize cAMP have been identified. Moreover, the biological roles of ACs/cAMP in response to stress remain largely unclear. In this study, we used quantitative proteomics techniques to identify a maize heat-induced putative disease-resistance RPP13-like protein 3 (ZmRPP13-LK3), which has three conserved catalytic AC centres. The AC activity of ZmRPP13-LK3 was confirmed by in vitro enzyme activity analysis, in vivo RNAi experiments, and functional complementation in the E. coli cyaA mutant. ZmRPP13-LK3 is located in the mitochondria. The results of in vitro and in vivo experiments indicated that ZmRPP13-LK3 interacts with ZmABC2, a possible cAMP exporter. Under heat stress, the concentrations of ZmRPP13-LK3 and cAMP in the ABA-deficient mutant vp5 were significantly less than those in the wild-type, and treatment with ABA and an ABA inhibitor affected ZmRPP13-LK3 expression in the wild-type. Application of 8-Br-cAMP, a cAMP analogue, increased heat-induced expression of heat-shock proteins in wild-type plants and alleviated heat-activated oxidative stress. Taken together, our results indicate that ZmRPP13-LK3, a new AC, can catalyse ATP for the production of cAMP and may be involved in ABA-regulated heat resistance.

Interaction of Cyclooxygenase-2 with Helicobacter pylori Induces Gastric Chronic Nonresolving Inflammation and the Formation of Syndrome of Internal Block of Static Blood in Helicobacter pylori-Related Gastric Diseases.

Cyclooxygenase-2 (COX-2) is an inducible enzyme stimulated by various inflammatory factors (IFs). Chronic gastritis is a classic model of "inflammation-cancer transformation" and Helicobacter pylori-related gastric diseases (HPGD) are specific ones of this model. Traditional Chinese Medicine (TCM) syndromes could play a predictive role in gastric histopathological evolution. To search for early warning evidence about "inflammation-cancer transformation," this study is about to explore interaction of COX-2 with Helicobacter pylori (Hp) in HPGD with different TCM syndromes. All included subjects underwent endoscopy and biopsy. Hp infection was detected by rapid urease test and methylene blue staining. Histopathological characteristics and COX-2 expression in gastric mucosa (GM) were, respectively, observed by hematoxylin-eosin and Elivision™ plus. SPSS 18.0 and Stata 11.0 statistical software packages were used for statistical analysis. Results of immunohistochemical staining in this study showed COX-2 expression in Hp-positive patients was stronger than that in Hp-negative ones. Spearman' analysis indicated that degrees of both Hp infection and COX-2 expression were positively correlated with those of gastric inflammation and inflammatory activity. Compared with the relative normal group, both severe dysplasia group and gastric carcinoma group had more severe Hp infection and COX-2 expression. Compared with the nonsyndrome, syndrome of internal block of static blood (IBSB) had higher scores in semiquantitative analysis of COX-2 protein expression among TCM groups. Moreover, multivariate logistics regression analysis suggested that patients with Hp infection could increase the risk of IBSB. These results indicated that COX-2 interacting with Hp could play an important role in transforming gastric chronic nonresolving inflammation into carcinoma in subjects with HPGD, as well as inducing the formation of IBSB. HPGD together with IBSB could be an early warning evidence for GM with histopathological evolution from benign to malignant.

An Atypical Thioredoxin Imparts Early Resistance to Sugarcane Mosaic Virus in Maize.

Sugarcane mosaic virus (SCMV) causes substantial losses of grain yield and forage biomass in susceptible maize worldwide. A major quantitative trait locus, Scmv1, has been identified to impart strong resistance to SCMV at the early infection stage. Here, we demonstrate that ZmTrxh, encoding an atypical h-type thioredoxin, is the causal gene at Scmv1, and that its transcript abundance correlated strongly with maize resistance to SCMV. ZmTrxh alleles, whether they are resistant or susceptible, share the identical coding/proximal promoter regions, but vary in the upstream regulatory regions. ZmTrxh lacks two canonical cysteines in the thioredoxin active-site motif and exists uniquely in the maize genome. Because of this, ZmTrxh is unable to reduce disulfide bridges but possesses a strong molecular chaperone-like activity. ZmTrxh is dispersed in maize cytoplasm to suppress SCMV viral RNA accumulation. Moreover, ZmTrxh-mediated maize resistance to SCMV showed no obvious correlation with the salicylic acid- and jasmonic acid-related defense signaling pathways. Taken together, our results indicate that ZmTrxh exhibits a distinct defense profile in maize resistance to SCMV, differing from previously characterized dominant or recessive potyvirus resistance genes.

Conclusiveness of the Cochrane Reviews in Palliative and Supportive Care for Cancer.

To assess the conclusiveness of the Cochrane reviews (CRs) in the field of palliative and supportive care for cancer. We searched the CRs on Pain, Palliative, and Supportive Care Group available in the Cochrane library on February 01, 2015, to analyze whether a CR could reach a clinical decision. Each CR was analyzed for conclusiveness, number of randomized controlled trials (RCTs) enrolled, number of participants enrolled, the need for further studies, and the reasons. Only 45% (30 of 66) of the CRs reached definitive clinical recommendations. The number of RCTs and participants enrolled in conclusive CRs were significantly higher than those in inconclusive CRs. Nearly all CRs recognized the need for further studies. The conclusiveness was not affected by the year of publication. We concluded that a large number of clinical trials were not carried out well in the palliative and supportive oncology.

Expression and prognostic significance of CCL11/CCR3 in glioblastoma.

Glioblastoma (GBM) is the most lethal primary nervous system cancer, but due to its rarity and complexity, its pathogenesis is poorly understood. To identify potential tumorigenic factors in GBM, we screened antibody-based cytokine arrays and found that CCL11 was upregulated. We then demonstrated in vitro that both CCL11 and its receptor, CCR3, were overexpressed and promoted the proliferation, migration and invasion of cancer cells. To examine the clinical significance of CCL11/CCR3, 458 GBM samples were divided into a training cohort with 225 cases and a test cohort containing 233 cases. In the training set, immunohistochemical analysis showed overexpression of CCL11 and CCR3 were correlated with unfavorable overall survival (OS). We further developed a prognostic classifier combining CCL11 and CCR3 expression and Karnofsky performance status (KPS) for predicting one-year survival in GBM patients. Receiver operating characteristic (ROC) analysis demonstrated that this predictor achieved 90.7% sensitivity and 73.4% specificity. These results were validated with the test sample set. Our findings suggest that CCL11-CCR3 binding is involved in the progression of GBM and may prompt a novel therapeutic approach. In addition, CCL11 and CCR3 expression, combined with KPS, may be used as an accurate predictor of one-year survival in GBM patients.

Conversion of adult human peripheral blood mononuclear cells into induced neural stem cell by using episomal vectors.

Human neural stem cells (NSCs) hold great promise for research and therapy in neural diseases. Many studies have shown direct induction of NSCs from human fibroblasts, which require an invasive skin biopsy and a prolonged period of expansion in cell culture prior to use. Peripheral blood (PB) is routinely used in medical diagnoses, and represents a noninvasive and easily accessible source of cells. Here we show direct derivation of NSCs from adult human PB mononuclear cells (PB-MNCs) by employing episomal vectors for transgene delivery. These induced NSCs (iNSCs) can expand more than 60 passages, can exhibit NSC morphology, gene expression, differentiation potential, and self-renewing capability and can give rise to multiple functional neural subtypes and glial cells in vitro. Furthermore, the iNSCs carry a specific regional identity and have electrophysiological activity upon differentiation. Our findings provide an easily accessible approach for generating human iNSCs which will facilitate disease modeling, drug screening, and possibly regenerative medicine.

Comparison of intracerebral transplantation effects of different stem cells on rodent stroke models.

In the present study, induced pluripotent stem cells (iPSCs), induced neural stem cells (iNSCs), mesenchymal stem cells (MSCs) and an immortalized cell line (RMNE6), representing different characteristics of stem cells, were transplanted into normal and/or injured brain areas of rodent stroke models, and their effects were compared to select suitable stem cells for cell replacement stroke therapy. The rat and mice ischaemic models were constructed using the middle cerebral artery occlusion technique. Both electrocoagulation of the artery and the intraluminal filament technique were used. The behaviour changes and fates of grafted stem cells were determined mainly by behaviour testing and immunocytochemistry. Following iPSC transplantation into the corpora striata of normal mice, a tumour developed in the brain. The iNSCs survived well and migrated towards the injured area without differentiation. Although there was no tumourigenesis in the brain of normal or ischaemic mice after the iNSCs were transplanted in the cortices, the behaviour in ischaemic mice was not improved. Upon transplanting MSC and RMNE6 cells into ischaemic rat brains, results similar to iNSCs in mice were seen. However, transplantation of RMNE6 caused a brain tumour. Thus, tumourigenesis and indeterminate improvement of behaviour are challenging problems encountered in stem cell therapy for stroke, and the intrinsic characteristics of stem cells should be remodelled before transplantation.

Prolonged overall survival in gastric cancer patients after adoptive immunotherapy.

AIM: To assess the efficacy of immunotherapy with expanded activated autologous lymphocytes (EAALs) in gastric cancer. METHODS: An observational study was designed to retrospectively analyze the clinical data of 84 gastric cancer patients, of whom 42 were treated by EAAL immunotherapy plus conventional treatment and another 42 only received conventional treatment (control group). EAALs were obtained by proliferation of peripheral blood mononuclear cells from patients followed by phenotype determination. Clinical data including age, gender, clinical stage, chemotherapeutic regimens, hospitalization, surgical, radiotherapy, and survival data were collected along with EAAL therapy details and side effects. Patients were followed and the relationship between treatment and overall survival (OS) data obtained for the immunotherapy and control groups were compared retrospectively. The safety of EAAL immunotherapy was also evaluated. RESULTS: After in vitro culture and proliferation, the percentages of CD3+, CD3+CD8+, CD8+CD27+, CD8+CD28+, and CD3+CD16+/CD56+ cells increased remarkably (P < 0.05), while the percentages of CD3+CD4+, CD4+CD25+, and CD3-CD16+/CD56+ (natural killer cells) were overtly decreased (P < 0.05); no significant change was observed in CD4+CD25+CD127- cells (P = 0.448). Interestingly, OS in the immunotherapy group was significantly higher than that in the control group, with 27.0 and 13.9 mo obtained for the two groups, respectively (P = 0.028, HR = 0.573, 95%CI: 0.347-0.945). These findings indicated a 42.7% decrease in the risk of death. In addition, we found that clinical stage and application of EAAL immunotherapy were independent prognostic factors for gastric cancer patients. Indeed, the OS in stage IIIc and IV patients that had received surgery was prolonged after EAAL immunotherapy (P < 0.05). Importantly, in vitro induction and proliferation of EAAL were easy and biologically safe. CONCLUSION: Overall, EAAL adoptive immunotherapy might prolong the OS in gastric cancer patients.

Revealing gene clusters associated with the development of cholangiocarcinoma, based on a time series analysis.

Cholangiocarcinoma (CC) is a rapidly lethal malignancy and currently is considered to be incurable. Biomarkers related to the development of CC remain unclear. The present study aimed to identify differentially expressed genes (DEGs) between normal tissue and intrahepatic CC, as well as specific gene expression patterns that changed together with the development of CC. By using a two­way analysis of variance test, the biomarkers that could distinguish between normal tissue and intrahepatic CC dissected from different days were identified. A k­means cluster method was used to identify gene clusters associated with the development of CC according to their changing expression pattern. Functional enrichment analysis was used to infer the function of each of the gene sets. A time series analysis was constructed to reveal gene signatures that were associated with the development of CC based on gene expression profile changes. Genes related to CC were shown to be involved in 'mitochondrion' and 'focal adhesion'. Three interesting gene groups were identified by the k­means cluster method. Gene clusters with a unique expression pattern are related with the development of CC. The data of this study will facilitate novel discoveries regarding the genetic study of CC by further work.

Autologous iPSC-derived dopamine neuron transplantation in a nonhuman primate Parkinson's disease model.

Autologous dopamine (DA) neurons are a new cell source for replacement therapy of Parkinson's disease (PD). In this study, we tested the safety and efficacy of autologous induced pluripotent stem cell (iPSC)-derived DA cells for treatment of a cynomolgus monkey PD model. Monkey bone marrow mesenchymal cells were isolated and induced to iPSCs, followed by differentiation into DA cells using a method with high efficiency. Autologous DA cells were introduced into the brain of a cynomolgus monkey PD model without immunosuppression; three PD monkeys that had received no grafts served as controls. The PD monkey that had received autologous grafts experienced behavioral improvement compared with that of controls. Histological analysis revealed no overgrowth of grafts and a significant number of surviving A9 region-specific graft-derived DA neurons. The study provided a proof-of-principle to employ iPSC-derived autologous DA cells for PD treatment using a nonhuman primate PD model.

Lmx1a enhances the effect of iNSCs in a PD model.

Lmx1a plays a central role in the specification of dopaminergic (DA) neurons, which potentially could be employed as a key factor for trans-differentiation to DA neurons. In our previous study, we have converted somatic cells directly into neural stem cell-like cells, namely induced neural stem cells (iNSCs), which further can be differentiated into subtypes of neurons and glia in vitro. In the present study, we continued to test whether these iNSCs have therapeutic effects when transplanted into a mouse model of Parkinson's disease (PD), especially when Lmx1a was introduced into these iNSCs under a Nestin enhancer. iNSCs that over-expressed Lmx1a (iNSC-Lmx1a) gave rise to an increased yield of dopaminergic neurons and secreted a higher level of dopamine in vitro. When transplanted into mouse models of PD, both groups of mice showed decreased ipsilateral rotations; yet mice that received iNSC-Lmx1a vs. iNSC-GFP exhibited better recovery. Although few iNSCs survived 11weeks after transplantation, the improved motor performance in iNSC-Lmx1a group did correlate with a greater tyrosine hydroxylase (TH) signal abundance in the lesioned area of striatum, suggesting that iNSCs may have worked through a non-autonomous manner to enhance the functions of remaining endogenous dopaminergic neurons in brain.

Heterogeneity of epidermal growth factor receptor mutations in lung adenocarcinoma harboring anaplastic lymphoma kinase rearrangements: A case report.

Lung cancer is a heterogeneous and complex disease that remains the leading cause of cancer-related mortality worldwide. The identification of epidermal growth factor receptor (EGFR) mutation and anaplastic lymphoma kinase (ALK) rearrangements has changed the treatment of non-small cell lung cancer, creating a personalized treatment era that is based on the appropriate molecular selection of patients. In spite of the efficacy of tyrosine kinase inhibitors (TKIs), acquired resistance remains inevitable due to various mechanisms. The present study reports the case of a 30-year-old patient with stage IV lung adenocarcinoma initially harboring an EGFR mutation. However, following disease progression and a series of treatments, the wild-type EGFR gene was observed and the ALK rearrangements were revealed. Erlotinib administration resulted in a good response in the patient initially, but crizotinib did not. This indicated an association between the secondary mutations in kinases and the drug resistance to TKIs. This case should also highlight the clinical significance of repeat biopsies for the subsequent therapeutic choices at the onset of clinical progression.

Adoptive immunotherapy for non-small cell lung cancer by NK and cytotoxic T lymphocytes mixed effector cells: retrospective clinical observation.

The objective of the current study was to retrospectively investigate the efficacy of adaptive transfer of natural killer (NK) and cytotoxic T lymphocytes mixed effector (NKTm) cells in non-small cell lung cancer (NSCLC) patients in comparison to a control group of NSCLC patients. NKTm cells were obtained by ex vivo expansion of peripheral blood mononuclear cells (PBMCs) of patients followed with phenotype determination. Primary end point was overall survival (OS). Ex vivo expansion caused significant enrichment of CD3(+), CD3(+)CD8(+), CD45RO(+), CD25(+), CD29(+) and CD3(+)CD16(+)/CD56(+) cells (P<0.05). The OS of the immunotherapy group was significantly longer than that of the control group and the risk of death decreased by 43.8% (31.1 months vs 18.1 months, P=0.008, HR=0.562, 95% CI 0.367-0.860). Two-year survival rate of patients in the immunotherapy group was better than in the control group (62.95% vs 35.44%, P<0.05). Gender, clinical stage, application of TKI, number of chemotherapy cycle, and application of NKTm immunotherapy were independent prognostic factors for NSCLC patients. The OS in subgroups of males, <60 years age, clinical stage IIIb+IV, no brain metastases, without radiotherapy, chemotherapy of >6 cycles, no application of TKI and TKI invalid was prolonged after NKTm cellular immunotherapy (P<0.05). Ex vivo expansion of NKTm cells was effective and had no adverse safety concerns, thus highlight that adaptive transfer of NKTm cells may prolong the OS of NSCLC patients and increase 2 year survival rate.

Allogeneic cell-based immunotherapy combined with chemotherapy and targeted therapy in advanced pancreatic cancer with metastases: A case report.

Immunotherapy may be an effective and potentially less toxic treatment for cancer in addition to the traditional therapies. The current study presents a case of advanced pancreatic cancer that was treated with cell-based immunotherapy using expanded activated allogeneic lymphocytes (EAAL*) in vitro with cluster of differentiation (CD)3(+) and CD8(+) cytotoxic T lymphocytes, and CD3(-) and CD56(+) natural killer cells as the major effector cells, together with chemotherapy and targeted agents. A 46-year-old female was diagnosed at the Chinese PLA General Hospital (Beijing, China) with stage IV pancreatic cancer with multiple metastases in October 2012. After receiving one cycle of chemotherapy plus nimotuzumab (Nimo), the patient received 14 infusions of EAAL*, which was obtained from a related donor, combined with seven cycles of chemotherapy with gemcitabine plus oxaliplatin and targeted therapy with Nimo. The patient was followed up for eight months. One day prior to the cell infusion, targeted therapy was administered and 48 h following the cell infusion, chemotherapy was administered. Following this treatment, carbohydrate antigen 19-9 levels decreased from 4,136 U/ml to within the normal ranges, along with the significant regression of the lesions. Occasionally mild upset was observed following the EAAL* transfusion. For the entire combined modality, grade II hematological and gastrointestinal toxicities plus grade I liver function damage and skin rash were identified. The present study demonstrated that combining allogeneic cell-based immunotherapy with conventional therapies is effective and safe, even in patients with end-stage pancreatic cancer. Therefore, this strategy is recommended for the treatment of similar cases.

Overexpression of a maize E3 ubiquitin ligase gene enhances drought tolerance through regulating stomatal aperture and antioxidant system in transgenic tobacco.

Drought is one of the most important limiting factors in crop production. In our previous study, a putative Arabidopsis thaliana SALT- AND DROUGHT-INDUCED RING FINGER1 (AtSDIR1) homolog encoding a RING-finger protein from Zea mays (ZmRFP1) was cloned and its expression pattern and Ub E3 ligase activity were characterized. However, it is uncertain that ZmRFP1 acts as a positive regulator during drought stress. In this study, we further characterized ZmRFP1 in transgenic tobacco to investigate drought tolerance and possible function mechanisms. Overexpression of ZmRFP1 enhanced drought tolerance in tobacco. The transgenic tobacco lines had more closed stomatal pores, higher proline accumulation, but lower levels of malondialdehyde (MDA) when compared with the wild type (WT) under drought stress. Further investigation showed that ZmRFP1 transgenic plants displayed higher SOD and CAT activities, increased NtSOD and NtCAT transcript levels, and decreased reactive oxygen species (ROS) accumulation under drought stress. Taken together, our results demonstrate that ZmRFP1 confers drought stress tolerance in transgenic tobacco not only by increasing the ability to retain water, but also by reducing ROS accumulation and membrane damage through enhancing the antioxidant system. ZmRFP1 might serve as a candidate gene in genetic improvement for drought tolerance engineering in cereal crop plants.

The maize AAA-type protein SKD1 confers enhanced salt and drought stress tolerance in transgenic tobacco by interacting with Lyst-interacting protein 5.

ATPase associated with various cellular activities (AAA) proteins are important regulators involved in diverse cellular functions. To date, the molecular mechanisms of AAA proteins involved in response to salt and drought stresses in plants are largely unknown. In this study, a putative SKD1 (suppressor of K(+) transport growth defect 1) ortholog from Zea mays (ZmSKD1), which encodes a putative AAA protein, was isolated. The transcript levels of ZmSKD1 were higher in aerial tissues and were markedly up-regulated by salt or drought stress. Over-expression of ZmSKD1 in tobacco plants enhanced their tolerances not only to salt but to drought. Moreover, reactive oxygen species accumulations in ZmSKD1 transgenic lines were relative less than those in wild-type plants during salt or PEG-induced water stress. The interaction between ZmSKD1 and NtLIP5 (Lyst-Interacting Protein 5 homolog from Nicotiana tabacum) was confirmed by both yeast two-hybrid and immuno-precipitation assays; moreover, the α-helix-rich domain in the C-terminus of ZmSKD1 was identified to be required for its interaction with NtLIP5 using truncation mutations. Collectively, these data demonstrate that ZmSKD1could be involved in salt and drought stress responses and its over-expression enhances salt or drought stress tolerance possibly through interacting with LIP5 in tobacco. This study may facilitate our understandings of the biological roles of SKD1-mediated ESCRT pathway under stress conditions in higher plants and accelerate genetic improvement of crop plants tolerant to environmental stresses.

Overexpression of a maize sulfite oxidase gene in tobacco enhances tolerance to sulfite stress via sulfite oxidation and CAT-mediated H2O2 scavenging.

Sulfite oxidase (SO) plays an important role in sulfite metabolism. To date, the molecular mechanisms of sulfite metabolism in plants are largely unknown. Previously, a full-length cDNA of the putative sulfite oxidase gene from maize (ZmSO) was cloned, and its response to SO(2)/sulfite stress at the transcriptional level was characterized. In this study, the recombinant ZmSO protein was purified from E. coli. It exhibited sulfite-dependent activity and had strong affinity for the substrate sulfite. Over-expression (OE) of ZmSO in tobacco plants enhanced their tolerance to sulfite stress. The plants showed much less damage, less sulfite accumulation, but greater amounts of sulfate. This suggests that tolerance of transgenic plants to sulfite was enhanced by increasing SO expression levels. Interestingly, H(2)O(2) accumulation levels by histochemical detection and quantitative determination in the OE plants were much less than those in the wild-type upon sulfite stress. Furthermore, reductions of catalase levels detected in the OE lines were considerably less than in the wild-type plants. This indicates that SO may play an important role in protecting CAT from inhibition by excess sulfite. Collectively, these data demonstrate that transgenic tobacco plants over-expressing ZmSO enhance tolerance to excess sulfite through sulfite oxidation and catalase-mediated hydrogen peroxide scavenging. This is the first SO gene from monocots to be functionally characterized.