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Jianhua Zhang

Publications and source records attributed to Jianhua Zhang.

At least 19 recordsLinked to original sources
PubMed2026

Paired analysis of primary adenoid cystic carcinoma and derived cell lines reveals a mesenchymal and stem-like shift associated with therapy resistance.

Adenoid cystic carcinoma (ACC) is a salivary gland malignancy characterized by slow but persistent growth, frequent local recurrence, and late metastatic progression. Patients with unresectable, recurrent, or metastatic disease have limited therapeutic options. Efforts to identify effective therapeutic targets have been hindered by the limited availability of well-characterized ACC models. In this study, we established 11 ACC cell lines and performed RNA sequencing of nine cell lines and their matched primary tumors to evaluate the preservation and evolution of molecular and lineage-associated characteristics during cell line establishment. Comparative transcriptomic analysis revealed reduced epithelial and luminal differentiation programs in the cell lines, accompanied by enrichment of myoepithelial, EMT-, and cancer stem cell-associated transcriptional programs. Digital deconvolution and single-sample gene set enrichment analysis supported enrichment of hybrid EMT/stem-like states during in vitro propagation, while comparison with publicly available primary-recurrent ACC data demonstrated partial preservation of recurrence-associated plasticity and invasion programs. Protein-level validation of representative epithelial, myoepithelial, EMT, and stemness markers supported the major transcriptomic changes. In addition, a cell line with a higher stemness signature showed reduced sensitivity to cisplatin. Together, these findings indicate that ACC cell line establishment is associated with transcriptional reprogramming and enrichment of plastic, EMT/stem-like states while retaining selected ACC lineage characteristics. These models provide experimentally tractable platforms for investigating ACC progression, therapeutic response, and mechanisms of treatment resistance.

Adenoid cystic carcinoma↗
PubMed2026

Intratumoral Sotigalimab with Pembrolizumab Induces Rapid Activation of Antigen-Presenting Cells and Drives Antitumor Responses in Non-injected Tumors in Metastatic Melanoma: A Phase I/II Study.

UNLABELLED: Immune checkpoint blockers (ICB) improve outcomes in metastatic melanoma (MM), but resistance limits benefit. This phase I/II (NCT02706353) study evaluated intratumoral sotigalimab (anti-CD40 agonist) with pembrolizumab in 32 patients with ICB-naïve MM. Primary endpoints were safety and objective response rate (ORR). Sotigalimab was well tolerated. At the recommended phase II dose, the ORR was 50%, and the disease control rate was 92%, with ORRs of 67% in injected and 50% in non-injected tumors. Multiomic analyses of tumor and blood showed that sotigalimab effectively engaged the CD40 pathway, boosting infiltration and activation of myeloid cells, including CD11c+DC-LAMP+ dendritic cells and macrophages. The combination therapy activated innate and adaptive immunity in injected tumors and cytotoxic responses in non-injected tumors. T-cell receptor sequencing showed increased T-cell clonality with expanded new clones shared across tumors. Clinical responses correlated with these immunologic changes but not with baseline features associated with response to anti-PD-1 monotherapy. SIGNIFICANCE: In this study, we provide compelling data that intratumoral sotigalimab combined with pembrolizumab is safe, activates antigen-presenting cells, and elicits broad innate and adaptive immune responses in both injected and non-injected tumors, supporting further randomized phase II trials to evaluate sotigalimab's potential to enhance anti-PD-1 therapy through "in situ" immunization.

Humans↗
PubMed2026

Decreased TXNRD1 is associated with resistance to tagraxofusp in blastic plasmacytoid dendritic cell neoplasms, as seen in phase II.

Tagraxofusp is a CD123-targeted therapy comprised of a recombinant human interleukin-3 (IL-3) fused to a truncated diphtheria toxin payload. It is the first approved treatment specifically for patients with blastic plasmacytoid dendritic cell neoplasm (BPDCN). To identify biomarkers of response, bone marrow samples from 12 BPDCN patients who were treated with tagraxofusp in the pivotal phase II trial (NCT02113982) were profiled longitudinally using a gene panel and single-cell RNA sequencing. Residual tumor cells following tagraxofusp expressed lower levels of TXNRD1 that would reduce the efficacy of tagraxofusp. In support of this, enzymatic inhibition of TXNRD1 resulted in higher viability of CAL-1 BPDCN cells following tagraxofusp. Responders had either wild-type or missense TET2 mutations, while transient and non-responders had at least one truncating TET2 mutation. Examples of these mutations within the catalytic domain of TET2 were constructed and transduced into cells. Missense and truncating mutants displayed reduced sensitivities to hypomethylating agents and prolonged S-phase stasis. These results suggest that the levels of TXNRD1 interact with intrinsic TET2 truncating mutations within the bone marrow to modulate patient response to tagraxofusp.

Female↗
PubMed2026

A stratified urine-based molecular diagnostic and prognostic model for non-muscle-invasive bladder cancer management.

BACKGROUND: Non-muscle-invasive bladder cancer (NMIBC) is characterized by a high recurrence rate requiring lifelong cystoscopic surveillance. Existing urine-based molecular assays mainly rely on mutations or methylation, which fail to capture large-scale genomic instability. Copy number variation (CNV) profiling offers complementary information on tumor evolution and aggressiveness, but its application in urinary diagnosis remains limited. We aimed to integrate CNV and DNA methylation signals from urinary DNA to establish a noninvasive and biologically informed stratified diagnostic model for NMIBC recurrence surveillance and risk stratification. METHODS: Urine samples were prospectively collected from 91 patients (75 evaluable) between June 2021 and August 2023. Shallow whole-genome sequencing (sWGS) was used to detect CNVs at chromosomal arm and focal gene levels, while ONECUT2 promoter methylation was quantified by qPCR. Diagnostic and prognostic performance was evaluated by ROC analysis, Kaplan-Meier survival, and stratified recurrence assessment. RESULTS: We evaluated a stratified diagnostic model combining CNV and ONECUT2 methylation testing in a cohort of 79 patients. CNV analysis alone showed high specificity (0.923) for NMIBC diagnosis. A combined model, using CNV as an initial screen followed by ONECUT2 methylation testing in CNV-positive cases, achieved a sensitivity of 0.783, specificity of 0.981, and a negative predictive value (NPV) of 0.911. This approach reduced the number of required ONECUT2 tests by 35% and identified a high proportion of true-negative patients (98.1%), which may help reduce unnecessary cystoscopy procedures. The model also demonstrated significant prognostic value, with the molecularly defined high-risk group showing significantly shorter recurrence-free survival (RFS) than the low-risk group (median RFS: 4.33 months vs. not reached; p&#x2009;<&#x2009;0.001). Additional, in patients with initially negative cystoscopy after urine sample collection, the model demonstrated a predictive accuracy of 0.922 for recurrence, with molecular positivity observed a median of 9.6 months prior to clinical diagnosis. CONCLUSIONS: Integrating CNV and DNA methylation profiling from urinary DNA provides a powerful and noninvasive molecular framework for NMIBC surveillance. By combining early epigenetic changes with genomic instability signals, this approach enhances recurrence risk assessment and enables earlier detection compared with conventional cystoscopy. It offers a practical route toward personalized and adaptive post-treatment monitoring of NMIBC. TRIAL REGISTRATION: NCT04994197.

Humans↗
PubMed2025

Triazole-resistant Aspergillus fumigatus in the Netherlands between 1994 and 2022: a genomic and phenotypic study.

BACKGROUND: Aspergillus fumigatus is the main cause of invasive aspergillosis and triazole antifungals are the primary treatment option. The effectiveness of triazole therapy is hampered by the emergence of resistance, mainly caused by mutations in the cyp51A gene and a tandem repeat (TR) of 34 bases (TR34/Leu98His) and 46 bases (TR46/Tyr121Phe/Thr289Ala) in the promoter region, which correspond with signature triazole resistance phenotypes. We aimed to investigate the occurrence of triazole phenotype and genotype variation over a 29-year period in the Netherlands. METHODS: In this genomic and phenotypic study, we screened all clinical A fumigatus isolates from Dutch hospitals collected between Jan 6, 1994, and Dec 31, 2022, for resistance to triazole using agar-based methods, and characterised them by sequencing the cyp51A gene and in vitro susceptibility testing using the European Committee on Antimicrobial Susceptibility Testing reference method. Whole-genome sequencing was performed on selected isolates, including those harboring TR34 variants, high-frequency single-nucleotide polymorphisms, and wild-type strains. Clinical information such as age, underlying disease, diagnosis, therapy, and outcomes was collected for patients who had isolates cultured at the Radboud University Medical Centre, Nijmegen, Netherlands, between Jan 1, 2017, and Dec 31, 2022. FINDINGS: 1979 (15&#xb7;6%) of the screened 12&#x2009;679 A fumigatus isolates harboured cyp51A triazole resistance mutations, predominately TR34/Leu98His sensu stricto in 1338 (67&#xb7;6%) resistant isolates and TR46/Tyr121Phe/Thr289Ala sensu stricto in 332 (16&#xb7;8%) resistant isolates. Phenotype and genotype variations were observed in 325 (17&#xb7;2%) triazole resistant isolates harbouring a TR-resistance mechanism, including 12 cyp51A genotype variants. Whole-genome sequencing showed that isolates with combinations of TR34-based and TR46-based polymorphisms seemed to be derived from separate populations, but there was some overlap. 59 cases of proven or probable invasive aspergillosis were identified, including 13 triazole-resistant cases, of which three were caused by genotype variants. Mixed genotype infection was observed in 11 (84&#xb7;6%) of 13 triazole-resistant patients and the number of antifungal treatment switches was higher compared with triazole-susceptible disease (p<0&#xb7;0001). INTERPRETATION: Our study showed variation in triazole genotypes and phenotypes in clinical A fumigatus isolates with cyp51A-mediated resistance, some of which were cultured from triazole-resistant invasive aspergillosis cases. Triazole resistance variation and mixed A fumigatus genotypes represent a major challenge in clinical management of Aspergillus diseases because current molecular diagnostic tools will increasingly fail to predict the resistance phenotype, underscoring the need for improved detection methods. FUNDING: National Key Research and Development Program of China, National Natural Science Foundation of China, and Wellcome Trust.

Aspergillus fumigatus↗
PubMed2024

Multiple sclerosis and abnormal spermatozoa: A bidirectional two-sample mendelian randomization study.

OBJECTIVE: Multiple sclerosis (MS) is an autoimmune disease of the central nervous system, and previous observational epidemiological studies have suggested an association between MS and male infertility; male infertility due to sperm abnormalities may result from a number of aetiological factors, such as genetics, autoimmune factors, etc., and there are currently no studies to assess whether MS is associated with sperm abnormalities in men. Therefore, we performed a Mendelian randomization (MR) analysis to assess the causal relationship between MS and abnormal spermatozoa. METHODS: In this study, independent single nucleotide polymorphisms (SNPs) strongly associated with multiple sclerosis (MS) were identified by mining public genome-wide association study repositories and used as instrumental variables to explore causality. The causal effect of MS on sperm abnormalities was systematically assessed using two-sample Mendelian randomization (MR) techniques, and various analytical models such as inverse variance weighting (IVW), MR-Egger and MR-PRESSO were implemented to dissect the association. In addition, a wide range of sensitivity tests, including Cochran's Q test to detect heterogeneity, MR-Egger intercept analysis to assess bias, leave-one-out to test model robustness, and funnel plot analysis to detect potential publication bias, were implemented to ensure the robustness and reliability of the causal inference results. RESULTS: There was a significant causal relationship between MS and abnormal sperm (OR 1.090, 95% CI [1.017-1.168], p = 0.014); The accuracy and robustness of the results were confirmed by sensitivity analysis. CONCLUSION: Here we show that there appears to be a causal relationship between multiple sclerosis and abnormal spermatozoa. MS as a chronic disease has a higher risk of concomitant sperm abnormalities in its male patients, and reproductive and fertility issues in men with MS should receive special attention from clinicians.

Humans↗
PubMed2022

Feasibility of a novel non-invasive swab technique for serial whole-exome sequencing of cervical tumors during chemoradiation therapy.

BACKGROUND: Clinically relevant genetic predictors of radiation response for cervical cancer are understudied due to the morbidity of repeat invasive biopsies required to obtain genetic material. Thus, we aimed to demonstrate the feasibility of a novel noninvasive cervical swab technique to (1) collect tumor DNA with adequate throughput to (2) perform whole-exome sequencing (WES) at serial time points over the course of chemoradiation therapy (CRT). METHODS: Cervical cancer tumor samples from patients undergoing chemoradiation were collected at baseline, at week 1, week 3, and at the completion of CRT (week 5) using a noninvasive swab-based biopsy technique. Swab samples were analyzed with whole-exome sequencing (WES) with mutation calling using a custom pipeline optimized for shallow whole-exome sequencing with low tumor purity (TP). Tumor mutation changes over the course of treatment were profiled. RESULTS: 216 samples were collected and successfully sequenced for 70 patients (94% of total number of tumor samples collected). A total of 33 patients had a complete set of samples at all four time points. The mean mapping rate was 98% for all samples, and the mean target coverage was 180. Estimated TP was greater than 5% for all samples. Overall mutation frequency decreased during CRT but mapping rate and mean target coverage remained at >98% and >180 reads at week 5. CONCLUSION: This study demonstrates the feasibility and application of a noninvasive swab-based technique for WES analysis which may be applied to investigate dynamic tumor mutational changes during treatment to identify novel genes which confer radiation resistance.

Exome↗
PubMed2007

Effects of acute "binge" cocaine on mRNA levels of mu opioid receptor and neuropeptides in dopamine D1 or D3 receptor knockout mice.

In humans, elevations of mu opioid receptor (MOP-r) binding potential (BP) in the frontal cortex (FC) are associated with cocaine craving during early abstinence. In rats, decreases in dopaminergic (DAergic) transmission in the medial FC are associated with increased cocaine-seeking behavior. DA D1 or D3 receptor homozygous knockout (D1-/- or D3-/-) mice offer the opportunity to test the roles of these specific receptors in regulating MOP-r gene expression in response to cocaine. In the present studies, we found an increase in basal MOP-r mRNA levels in the FC of both D1-/- and D3-/- mice compared to wild type controls, with no change in the nucleus accumbens (NAc) core or caudate-putamen (CPu). Acute "binge" cocaine (3 x 15 mg/kg for 2.5 h) returned FC MOP-r mRNA levels in D1-/- or D3-/- mice to those in wild type controls. In the NAc core, the MOP-r mRNA levels after acute "binge" cocaine were decreased in D1-/- mice while increased in D3-/- mice. In the CPu, however, the MOP-r mRNA levels after acute "binge" cocaine were increased in D1-/- mice while decreased in D3-/- mice. We also found a decrease in basal orexin mRNA levels in the lateral hypothalamus of the D3-/- mice, which was unaltered by acute "binge" cocaine. Together, our findings suggest that: (1) both D1 and D3 receptors are involved in FC MOP-r gene regulation; and (2) D1 and D3 receptors play opposite roles in the effects of cocaine on MOP-r gene regulation differentially in the NAc core or CPu.

Animals↗
PubMed2007

Calcium-calmodulin is required for abscisic acid-induced antioxidant defense and functions both upstream and downstream of H2O2 production in leaves of maize (Zea mays) plants.

* Using pharmacological and biochemical approaches, the role of calmodulin (CaM) and the relationship between CaM and hydrogen peroxide (H(2)O(2)) in abscisic acid (ABA)-induced antioxidant defense in leaves of maize (Zea mays) plants were investigated. * Treatment with ABA or H(2)O(2) led to significant increases in the concentration of cytosolic Ca(2+) in the protoplasts of mesophyll cells and in the expression of the calmodulin 1 (CaM1) gene and the content of CaM in leaves of maize plants, and enhanced the expression of the antioxidant genes superoxide dismutase 4 (SOD4), cytosolic ascorbate peroxidase (cAPX), and glutathione reductase 1 (GR1) and the activities of the chloroplastic and cytosolic antioxidant enzymes. The up-regulation of the antioxidant enzymes was almost completely blocked by pretreatments with two CaM antagonists. * Pretreatments with CaM antagonists almost completely inhibited ABA-induced H(2)O(2) production throughout ABA treatment, but pretreatment with an inhibitor or scavenger of reactive oxygen species (ROS) did not affect the initial increase in the contents of CaM induced by ABA. * Our results suggest that Ca(2+)-CaM is involved in ABA-induced antioxidant defense, and that cross-talk between Ca(2+)-CaM and H(2)O(2) plays a pivotal role in ABA signaling.

Abscisic Acid↗
PubMed2006

Nitric oxide activation of peroxisome proliferator-activated receptor gamma through a p38 MAPK signaling pathway.

Both nitric oxide (NO*) and peroxisome proliferator-activated receptors (PPARs) protect the endothelium and regulate its function. Here, we tested for crosstalk between these signaling pathways. Human umbilical vein and hybrid EA.hy926 endothelial cells were exposed to S-nitrosoglutathione (GSNO) or diethylenetriamine NONOate (DETA NONOate). Electrophoretic mobility shift assays using PPAR-response element (PPRE) probe showed that NO* caused a rapid dose-dependent increase in PPARgamma binding, an effect that was confirmed in vivo by chromatin immunoprecipitation. Conversely, N(G)-monomethyl-L-arginine, a NOS inhibitor, decreased PPARgamma binding. NO*-mediated PPARgamma binding and NO* induction of cyclooxygenase-2 (COX-2), diacylglycerol (DAG) kinase alpha (DGKalpha), and heme oxygenase-1 (HO-1), genes with well-characterized PPRE motifs, were cGMP independent. NO* dose dependently activated p38 MAPK, and p38 MAPK inhibition with SB202190 or knockdown with siRNA was shown to block NO* activation of PPARgamma. Likewise, p38 MAPK and PPARgamma inhibitors or knockdown of either transcript all significantly blocked NO* induction of PPRE-regulated genes. PPARgamma activation by p38 MAPK may contribute to the anti-inflammatory and cytoprotective effects of NO* in the vasculature. This crosstalk mechanism suggests new strategies for preventing and treating vascular dysfunction.

Cells, Cultured↗
PubMed2006

Kainic acid induces early and transient autophagic stress in mouse hippocampus.

Kainic acid (KA) treatment is a well-established model of hippocampal neuron death mediated in large part by KA receptor-induced excitotoxicity. KA-induced, delayed neuron death has been shown previously to follow the induction of seizures and exhibit characteristics of both apoptosis and necrosis. Growing evidence supports a role of autophagic stress-induced death of neurons in several in vitro and in vivo models of neuron death and neurodegeneration. However, whether autophagic stress also plays a role in KA-induced excitotoxicity has not been previously investigated. To examine whether KA alters the levels of proteins associated with or known to regulate the formation of autophagic vacuoles, we isolated hippocampal extracts from control mice and in mice following 2-16 h KA injection. KA induced a significant increase in the amount of LC3-II, a specific marker of autophagic vacuoles, at 4-6h following KA, which indicates a transient induction of autophagic stress. Levels of autophagy-associated proteins including ATG5 (conjugated to ATG12), ATG6 and ATG7 did not change significantly after treatment with KA. However, ratios of phospho-mTOR/mTOR were elevated from 6 to 16 h, and ratios of phospho-Akt/Akt were elevated at 16 h following KA treatment, suggesting a potential negative feedback loop to inhibit further stimulation of autophagic stress. Together these data indicate the transient induction of autophagic stress by KA which may serve to regulate excitotoxic death in mouse hippocampus.

Animals↗
PubMed2006

c-Fos facilitates the acquisition and extinction of cocaine-induced persistent changes.

Development of drug addiction involves persistent neurobiological changes. The dopamine D1 receptor is involved in mediating cocaine-induced neuroadaptation, yet the underlying intracellular mechanisms remain unclear. We examined a potential role of the immediate early gene Fos, which is robustly and rapidly induced by cocaine via D1 receptors, in mediating cocaine-induced persistent neurobiological changes by creating and analyzing a mouse in which Fos is primarily disrupted in D1 receptor-expressing neurons in the brain. We show that the expression levels of several transcription factors, neurotransmitter receptors, and intracellular signaling molecules induced by repeated cocaine administration are altered in Fos-deficient brains. Dendritic remodeling of medium spiny neurons induced by repeated exposure to cocaine is blunted in the mutant mice. The mutant mice exhibit attenuated behavioral sensitization after repeated exposure to cocaine and more persistent memory of cocaine-induced conditioned place preference. Our findings indicate that c-Fos produced in D1 receptor-expressing neurons integrates mechanisms to facilitate both the acquisition and extinction of cocaine-induced persistent changes.

Animals↗
PubMed2006

Nitric oxide down-regulates polo-like kinase 1 through a proximal promoter cell cycle gene homology region.

Polo-like kinase 1 (PLK1) is an evolutionarily conserved serine/threonine kinase essential for cell mitosis. As a master cell cycle regulator, p21/Waf1 plays a critical role in cell cycle progression. Nitric oxide (NO.) has been shown to down-regulate PLK1 and up-regulate p21/Waf1 independent of cGMP. Here, the respective roles of p38 MAPK and p21/Waf1 in NO.-mediated PLK1 repression were investigated using differentiated U937 cells that lack soluble guanylate cyclase. NO. was shown to down-regulate both PLK1 mRNA and protein. Nuclear run-on assays and mRNA stability studies demonstrated that the effect of NO. on PLK1 expression was associated with decreased transcription without changes in transcript stability. SB202190, a p38 MAPK inhibitor, prevented transcriptional repression of PLK1 by NO.. Transfection with dominant-negative p38 MAPK mutant eliminated the NO. effect on both p21/Waf1 and PLK1 gene expression. Knockdown of p21/Waf1 with siRNA also substantially reduced the regulatory effect of NO. on PLK1. Reporter gene experiments showed that NO. decreased activity of the PLK1 proximal promoter, an effect that was blocked by p38 MAPK inhibitor. Deletion or mutation of the CDE/CHR promoter site, an element regulated by p21/Waf1, increased base-line promoter activity and abolished NO. repression of the PLK1 promoter. Likewise, electrophoretic mobility shift assays with CDE/CHR probe revealed a NO.-mediated change in protein-probe complex formation. Competition with various unlabeled CDE/CHR mutant sequences showed that NO. increased nuclear protein binding to intact CHR. These results demonstrate that a NO.-p38 MAPK-p21/Waf1 signal transduction pathway represses PLK1 through a canonical CDE/CHR promoter element.

Cell Cycle Proteins↗
PubMed2006

Upregulation of vitamin D binding protein (Gc-globulin) binding sites during neutrophil activation from a latent reservoir in azurophil granules.

Vitamin D binding protein (DBP) is a multifunctional plasma transport protein that is also found on the surface of many cell types. Cell surface DBP significantly enhances chemotactic activity of complement (C) peptides C5a and C5a des Arg. However, both DBP binding and C5a chemotaxis enhancement can vary among neutrophil donors. To test if activation during cell purification is responsible for this variability, neutrophils were isolated using both standard and lipopolysaccharide (LPS)-free protocols. Cells isolated by the LPS-free method had no DBP-enhanced chemotaxis to C5a or DBP binding to plasma membranes. Moreover, neutrophils treated with LPS bound more avidity to immobilized DBP than sham-treated cells. Subcellular fractionation of neutrophils (standard protocol) revealed a heavy plasma membrane (HM) band that contained components of light plasma membranes and all three granules. The HM band possessed most of the DBP binding activity (58%), and activation of cells with ionomycin greatly increased DBP binding to HM. Azurophil granules contained 33% of the total DBP binding sites and there was a highly significant positive correlation (r=0.988) between release of the granule marker myeloperoxidase and DBP binding. These results indicate that fusion of granules with the plasma membrane forms HM that contains DBP binding sites.

Binding Sites↗
PubMed2006

Abscisic acid is a key inducer of hydrogen peroxide production in leaves of maize plants exposed to water stress.

The histochemical and cytochemical localization of water stress-induced H(2)O(2) production in the leaves of ABA-deficient vp5 mutant and wild-type maize (Zea mays L.) plants were examined, using 3,3-diaminobenzidine and CeCl(3) staining, respectively, and the roles of endogenous ABA in the production of H(2)O(2) induced by water stress were assessed. Water stress induced by polyethylene glycol resulted in the accumulation of H(2)O(2) in mesophyll cells, bundle-sheath cells and vascular bundles of wild-type maize leaves, and the accumulation was substantially blocked in the mutant maize leaves exposed to water stress. Pre-treatments with several apoplastic H(2)O(2) manipulators abolished the majority of H(2)O(2) accumulation induced by water stress in the wild-type leaves. The subcellular localization of H(2)O(2) production was demonstrated in the cell walls, xylem vessels, chloroplasts, mitochondria and peroxisomes in the leaves of wild-type maize plants exposed to water stress, and the accumulation of H(2)O(2) induced by water stress in the cell walls and xylem vessels, but not in the chloroplasts, mitochondria and peroxisomes, was arrested in the leaves of the ABA mutant or the ABA biosynthesis inhibitor (tungstate)-pre-treated maize plants. Pre-treatments with the apoplastic H(2)O(2) manipulators also blocked the apoplastic but not the intracellular H(2)O(2) accumulation induced by water stress in the leaves of wild-type plants. These data indicate that under water stress, the apoplast is the major source of H(2)O(2) production and ABA is a key inducer of apoplastic H(2)O(2) production. These data also suggest that H(2)O(2) generated in the apoplast could not diffuse freely into subcellular compartments.

Abscisic Acid↗
PubMed2006

Dynamic analysis of ABA accumulation in relation to the rate of ABA catabolism in maize tissues under water deficit.

The plant hormone abscisic acid (ABA) accumulates in plant tissues which experience water deficit (stress ABA). This study analysed its accumulation as a function of both synthesis and catabolism in maize tissues. By following the disappearance of the stress ABA when ABA synthesis was blocked by nordihydroguaiaretic acid (NDGA), the rate of the catabolism of stress ABA was determined. When compared with the catabolic rate of baseline (non-stress) ABA, stress ABA showed a catabolic rate >11 times higher. With such an elevated catabolic rate, it is proposed that the xanthophyll precursor pool may not be able to sustain the ABA accumulation, and such a proposition has been substantiated by further experiments where fluridone is used to limit the availability of upstream ABA precursors. When fluridone was used, stress ABA accumulation could only be sustained for a few hours, i.e. approximately 5 h for leaf and 1 h for root tissues. In detached roots, stress ABA accumulation could not be sustained even if fluridone was not used, suggesting that stress ABA accumulation in root systems requires the continuous import of ABA precursors from the shoots. Such an assumption was substantiated by the observation that defoliation or shading significantly reduced ABA accumulation in intact roots. The present study suggests that ABA catabolism is rapid enough to play an important role in the regulation of ABA accumulation.

Abscisic Acid↗
PubMed2006

Altered distributions of nucleocytoplasmic transport-related proteins in the spinal cord of a mouse model of amyotrophic lateral sclerosis.

Recent investigations have indicated that the nucleocytoplasmic transport system is essential for maintaining cell viability and cellular functions and that its dysfunction could lead to certain disorders. To investigate the involvement of this system in the pathomechanisms of amyotrophic lateral sclerosis (ALS), we examined the immunohistochemical localization of proteins associated with nucleocytoplasmic transport in the lumbar spinal cord in a mutant SOD1 (G93A) transgenic mouse model of ALS. This model is widely used for ALS research, and the mutant mice are known to exhibit neuronal loss and Lewy body-like hyaline inclusions (LBHIs) in the anterior horns, similar to the pathology seen in familial ALS patients associated with an SOD1 mutation and in several other transgenic rodent models. Using antibodies against the importin beta family of proteins, the major carrier proteins of nucleocytoplasmic transport, and those against their adapter protein, importin alpha, we found that the immunoreactivities were decreased within the nuclei and increased within the cytoplasm of a subset of the surviving anterior horn cells of the transgenic mice. In addition, LBHIs were invariably reactive toward these antibodies. Furthermore, the immunoreactivities for histone H1 and beta-catenin, representative cargo proteins transported by importin beta-dependent and beta-independent nucleocytoplasmic transport pathways, respectively, showed distributions similar to those for importin beta family and importin alpha proteins. The altered distributions of these proteins were not associated with caspase-3 expression, suggesting that the findings are unlikely to be a manifestation of apoptotic processes. Chronological quantitative analysis of importin beta-immunostained sections from the transgenic mice revealed a statistically significant progressive decrease in the proportion of the anterior horn cells exhibiting a more intense reactivity for these proteins in the nucleus than in the cytoplasm. To the contrary, we found that the anterior horn cells with the immunoreactivity in their cytoplasm, being more pronounced than that in their nucleus, were significantly increased in number along with the disease progression. This is the first report investigating nucleocytoplasmic transport in the ALS model mouse, and our present results imply that its dysfunction could be involved in the pathomechanisms underlying ALS.

Amyotrophic Lateral Sclerosis↗