Succinate Dehydrogenase Research Articles

Amino acid substitutions in succinate dehydrogenase complex conferring resistance to the SDHI fungicide pydiflumetofen in Cochlibolus heterostrophus causing southern corn leaf blight1

Southern corn leaf blight (SCLB) caused by Cochlibolus heterostrophus, is a widespread foliar disease that has a substantial impact on maize yield in the Huanghuaihai region of China. Pydiflumetofen (Pyd), a new succinate dehydrogenase inhibitor (SDHI), has been found as a promising fungicide for the efficient control of SCLB, however, resistance of C. heterostrophus to Pyd has not been studied well. Here, five Pyd-resistant mutants were generated through fungicide adaptation. Sequence alignment analysis revealed that these mutants primarily mutated in ChSdhB and ChSdhD, with 3 genotypes: ChSdhBH277Y, ChSdhBI279T and ChSdhDH133Y, exhibiting two distinct categories of resistance: high resistance (HR) and moderate resistance (MR), which resistance factors (RF) is 214.22 and 44.33-53.67, respectively. These mutants were more pathogenic than the wild-type parental strains, but there was a significant reduction in mycelial growth rate and sporulation in the resistant mutants, indicating a significant fitness cost associated with resistance to Pyd. In addition, this study revealed a positive cross-resistance between Pyd and another SDHI fungicide cyclobutrifluram. However, no cross-resistance was found between Pyd and other classes of fungicide, including prochloraz, fludioxonil, iprodioneand pyraclostrobin. Homology modeling and molecular docking further confirmed that point mutation of ChSdhBH277Y, ChSdhBI279T, and ChSdhDH133Y could reduce binding affinity between Pyd and its target subunits from −74.07, −74.07, −152.52 kcal mol-1 to −3.90, −4.95, −9.93 kcal/mol, respectively. These findings not only provided valuable insights for managing SCLB caused by C. heterostrophus, but also enhanced our understanding of molecular mechanism underlying plant pathogen resistance to Pyd.

Explore the action mechanism of Danggui Buxue decoction on chronic heart failure in rats by proteomics and untargeted metabolomics

Background and aimDanggui Buxue Decoction (DBD) has been applied to alleviate chronic heart failure (CHF) in clinics, however, its mechanism is still unclear. This study investigates the potential action mechanism of DBD for rats with CHF combined with liver injury. Experimental procedureFor this purpose, this study established a CHF rat model. The change of proteins in myocardial tissues was identified by proteomics and then further verified using western blotting. Additionally, metabolomics revealed the metabolic pathways associated with liver injury in CHF rats. Results and conclusionAnimal studies demonstrated that DBD could relieve CHF as it significantly reduced serum levels of brain natriuretic peptide (BNP), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) in CHF rats, and promoted the activity of catalase (CAT), glutathione peroxidase (GSH-Px), cytochrome oxidase (COX), and succinate dehydrogenase (SDH) in myocardial tissues. Myocardial proteomics analysis revealed that DBD improved myocardial mitochondria and peroxisomes function by regulating the expression of proteins associated with energy metabolism and oxidative damage. Western blotting confirmed that DBD upregulated the expression of proteins in the adenosine 5′-monophosphate (AMP)-activated protein kinase (AMPK)/silent mating type information regulation 2 homolog-1 (SIRT1)/peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1 α)/peroxisome proliferator-activated receptor beta (PPAR β) signaling pathway, which also proved the efficacy of DBD in alleviating CHF in rats. Hepatic metabolomics analysis showed that DBD could restore the damaged liver function of CHF rats via metabolic pathways, including the metabolism of lipid, vitamin, and amino acids. In conclusion, this study unveiled a novel action mechanism of DBD in the treating ISO-induced CHF and liver injury based on proteomics and metabolomics. These results lay a scientific basis for the widespread application of DBD in the cardiovascular field.

SDHA-related phaeochromocytoma and paraganglioma: review and clinical management.

Phaeochromocytomas and paragangliomas (collectively termed PPGL) are rare yet highly heritable neuroendocrine tumours, with over one-third of cases associated with germline pathogenic variants (PVs) in numerous genes. PVs in the succinate dehydrogenase subunit-A gene (SDHA) were initially implicated in hereditary PPGL in 2010, and SDHA has since become an important susceptibility gene accounting for up to 2.8% of cases. However, it remains poorly understood, particularly regarding the clinical nature of SDHA PPGL, rates of recurrence and metastasis, and the nature of metastatic disease. We present a narrative review of SDHA-related PPGL, covering pathophysiology, relevance to current clinical practice, and considerations for clinical genetics. We analyse a pool of 107 previously reported cases of SDHA-associated PPGL to highlight the spectrum of SDHA-related PPGL. Our analysis demonstrates that SDHA PPGL occurs across a wide age range (11-81 years) and affects men and women equally. SDHA PPGL typically presents as single tumours (91%), usually occurring in the head and neck (46%) or abdomen (43%, including 15% with phaeochromocytomas). Metastatic disease was reported in 25.5% of cases, with bone (82%) and lymph nodes (71%) being the most common sites of metastasis, often identified many years after the initial diagnosis. A family history of SDHA-related neoplasia was rare, reported in only 4% of cases. Understanding the clinical nature and risks associated with SDHA PVs is essential for facilitating the optimal management of patients and their families.

Active Heme Metabolism Suppresses Macrophage Phagocytosis via the TLR4/Type I IFN Signaling/CD36 in Uterine Endometrial Cancer.

Uterine endometrial cancer (UEC) is a common gynecological estrogen-dependent carcinoma, usually accompanied by intermenstrual bleeding. Active heme metabolism frequently plays an increasingly important role in many diseases, especially in cancers. Tumor-associated macrophages (TAMs) are the major population in the immune microenvironment of UEC. However, the roles of heme metabolisms in the crosstalk between UEC cells (UECCs) and macrophages are unclear. In our study, by using TCGA database analysis, integration analysis of the protein-protein interaction (PPI) network and sample RNA transcriptome sequencing were done. The expression level of both heme-associated molecules and iron metabolism-related molecules were measured by quantitative real-time polymerase chain reaction. Heme level detection was done through dehydrohorseradish peroxidase assay. In addition to immunohistochemistry, phagocytosis assay of macrophages, immunofluorescence staining, intracellular ferrous iron staining, as well as enzyme-linked immune sorbent assay were performed. In the study, we verified that heme accumulation in UECCs is apparently higher than in endometrial epithelium cells. Low expression of succinate dehydrogenase B under the regulation of estrogen contributes to over-production of succinate and heme accumulation in UECC. More importantly, excessive heme in UECCs impaired macrophage phagocytosis by regulation of CD36. Mechanistically, this process is dependent on toll-like receptor (TLR4)/type I interferons alpha (IFN Iα) regulatory axis in macrophage. Collectively, these findings elucidate that active heme metabolism of UECCs directly decreases phagocytosis by controlling the secretion of TLR4-mediated IFN Iα and the expression of CD36, and further contributing to the immune escape of UEC.

Sensitivity of Meloidogyne incognita and Rotylenchulus reniformis to Cyclobutrifluram.

Cyclobutrifluram, a succinate dehydrogenase inhibitor fungicide, is being evaluated as a seed-applied nematicide in cotton and soybean to manage plant-parasitic nematodes. Currently, there is no information on the toxicity, ovicidal activity, nematode recovery, or effects on nematode infection for Meloidogyne incognita or Rotylenchulus reniformis after exposure to low concentrations of cyclobutrifluram. Nematode toxicity assays were performed in aqueous solutions of cyclobutrifluram, and root infection assays were conducted on tomato. Nematode paralysis was observed after 2 h of exposure to 0.5 μg/ml cyclobutrifluram for both nematode species. Based on an assay of nematode motility, the 2-h effective concentration of fungicide required for 50% growth inhibition (EC50) value for M. incognita and R. reniformis was 0.48 and 1.07 μg/ml, respectively. In a comparable assay with a similar nematicide, continuous exposure to 0.5 μg/ml cyclobutrifluram for 24 h resulted in at least 45% more immotile nematodes for both species compared with those treated with 0.5 μg/ml fluopyram. Continuous exposure to concentrations greater than 1.0 μg/ml suppressed hatching for both species compared with the water control. Nematode recovery from paralysis was greater than 80% for M. incognita and R. reniformis 24 h after nematodes were rinsed and removed from a 1-h treatment to their respective 2-h EC50 concentrations. Nematode infection of tomato roots was reduced following a 1-h treatment with aqueous solutions of cyclobutrifluram, ranging from 0.12 to 0.48 μg/ml for M. incognita and 0.27 to 1.07 μg/ml for R. reniformis. Overall, the toxicity of cyclobutrifluram to these nematode species was greater than that of fluopyram, and although the effects of cyclobutrifluram were reversible, low concentrations were effective at reducing the ability of both nematodes to infect tomato roots.

Mitochondrial diabetes in mice expressing a dominant-negative allele of nuclear respiratory factor-1 (Nrf1) in pancreatic β-cells

Genetic polymorphisms in nuclear respiratory factor-1 (Nrf1), a key transcriptional regulator of nuclear-encoded mitochondrial proteins, have been linked to diabetes. Homozygous deletion of Nrf1 is embryonic lethal in mice. Our goal was to generate mice with β-cell-specific reduction in NRF1 function to investigate the relationship between NRF1 and diabetes. We report the generation of mice expressing a dominant-negative allele of Nrf1 (DNNRF1) in pancreatic β-cells. Heterozygous transgenic mice had high fed blood glucose levels detected at 3 wks of age, which persisted through adulthood. Plasma insulin levels in DNNRF1 transgenic mice were reduced, while insulin sensitivity remained intact in young animals. Islet size was reduced with increased numbers of apoptotic cells, and insulin content in islets by immunohistochemistry was low. Glucose-stimulated insulin secretion in isolated islets was reduced in DNNRF1-mice, but partially rescued by KCl, suggesting that decreased mitochondrial function contributed to the insulin secretory defect. Electron micrographs demonstrated abnormal mitochondrial morphology in β-cells. Expression of NRF1 target genes Tfam, Tfb1m and Tfb2m, and islet cytochrome c oxidase and succinate dehydrogenase activities were reduced in DNNRF1-mice. Rescue of mitochondrial function with low level activation of transgenic c-Myc in β-cells was sufficient to restore β-cell mass and prevent diabetes. This study demonstrates that reduced NRF1 function can lead to loss of β-cell function and establishes a model to study the interplay between regulators of bi-genomic gene transcription in diabetes.

Design, Synthesis, Antifungal Activity, and Mechanism of Action of New Piperidine-4-carbohydrazide Derivatives Bearing a Quinazolinyl Moiety.

A series of new piperidine-4-carbohydrazide derivatives bearing a quinazolinyl moiety were prepared and evaluated for their fungicidal activities against agriculturally important fungi. Among these derivatives, the chemical structure of compound A45 was clearly verified by X-ray crystallographic analysis. The antifungal bioassays revealed that many compounds in this series possessed good to excellent inhibition effects toward the tested fungi. For example, compounds A13 and A41 had EC50 values of 0.83 and 0.88 μg/mL against Rhizoctonia solani in vitro, respectively, superior to those of positive controls Chlorothalonil and Boscalid (1.64 and 0.96 μg/mL, respectively). Additionally, the above two compounds also exhibited notable inhibitory activities against Verticillium dahliae (with EC50 values of 1.12 and 3.20 μg/mL, respectively), far better than the positive controls Carbendazim and Chlorothalonil (19.3 and 11.0 μg/mL, respectively). More importantly, compound A13 could potently inhibit the proliferation of R. solani in the potted rice plants, showing good in vivo curative and protective efficiencies of 76.9% and 76.6% at 200 μg/mL, respectively. Furthermore, compound A13 demonstrated an effective inhibition of succinate dehydrogenase (SDH) activity in vitro with an IC50 value of 6.07 μM. Finally, the molecular docking study revealed that this compound could be well embedded into the active pocket of SDH via multiple noncovalent interactions, involving residues like SER39, ARG43, and GLY46.

Broncho-obstructive syndrome and the enzymes of cellular energy metabolism after coronavirus infection

Broncho-obstructive syndrome (BOS) after coronavirus infection is characterized by long-term, dry and painful cough which is hard for treatment, significantly reducing the quality of life of the patients. The goal of the study: to investigate the specific features of clinical manifestations of BOS diagnosed for the first time in patients belonging to different age groups in post-COVID-19 period and to estimate the degree of mitochondrial dysfunction by the imbalance of the enzymes of cellular energy metabolism. Materials and methods. 298 patients with BOS (age 18–78) were observed continuously for 2 years. Standard clinical, biochemical and functional examination was carried out, Saint George`s Respiratory Questionnaire (SGRQ) was used. Mitochondrial dysfunction was determined by the ratio of levels of two enzymes, lactate dehydrogenase (LDH) and succinate dehydrogenase (SDH), in peripheral blood lymphocytes. Statistical data processing was performed in STATISTICA 10.1 program package. Results. The duration and severity of BOS manifestations increased with age, they were the most prominent in the age group older than 60 y/o. Bronchial asthma was diagnosed for the first time in 85 patients, most of them belonging to the group 18–25 y/o. In all the patients with BOS, the SGRQ coeffitient was above 50, and comorbidity was established in 82.4% of the patients. The longest duration of BOS (49.4±3.5 days) was established in the group older than 60 y/o (n = 86). LDH/SDH ratio decreased from 6 to 4.8–5.2 a.u. in all the age groups. Such changes should be taken into account in the patients from young age groups. Conclusion. The revealed low values of LDH/SDH ratio have not been shown in the available literature earlier. These values demonstrate the development of secondary mitochondrial dysfunction in post-COVID-19 period in both younger and older age groups, particularly, in patients with more severe progression of BOS. Estimation of this parameter would allow to revealthe personified characteristics for each patients, which is important for quantifying the efficacy and duration of the required antioxidant therapy.

Design, Synthesis, and Biological Activity of Silicon-Containing Carboxamide Fungicides.

Bioisosteric silicon replacement has proven to be a valuable strategy in the design of bioactive molecules for crop protection and drug development. Twenty-one novel carboxamides possessing a silicon-containing biphenyl moiety were synthesized and tested for their antifungal activity and succinate dehydrogenase (SDH) enzymatic inhibitory activity. Among these novel succinate dehydrogenase inhibitors (SDHIs), compounds 3a, 3e, 4l, and 4o possessing appropriate clog P and topological polar surface area values showed excellent inhibitory effects against Rhizoctonia solani, Sclerotinia sclerotiorum, Botrytis cinerea, and Fusarium graminearum at 10 mg/L in vitro, and the EC50 values of 4l and 4o were 0.52 and 0.16 mg/L against R. solani and 0.066 and 0.054 mg/L against S. sclerotiorum, respectively, which were superior to those of Boscalid. Moreover, compound 3a demonstrated superior SDH enzymatic inhibitory activity (IC50 = 8.70 mg/L), exhibiting 2.54-fold the potency of Boscalid (IC50 = 22.09 mg/L). Docking results and scanning electron microscope experiments revealed similar mode of action between compound 3a and Boscalid. The new silicon-containing carboxamide 3a is a promising SDHI candidate that deserves further investigation.

Identification of Succinate Dehydrogenase Gene Variant Carriers by Blood Biomarkers.

Carriers of germline pathogenic variants (PVs) in succinate dehydrogenase genes (SDHx) are at risk of developing tumors, including paragangliomas, gastrointestinal stromal tumors, and renal cell carcinomas. Early tumor detection is paramount for improved clinical outcome. Blood-based biomarkers could aid in identifying individuals with PVs early and provide functional evidence in patients with variants of unknown significance. Blood plasma, urine, peripheral blood mononuclear cells, and erythrocytes from patients with and without SDHx PVs were investigated for central carbon metabolites. These were measured by liquid chromatography-tandem mass spectrometry and nuclear magnetic resonance spectroscopy and included among others, succinate, fumarate, α-ketoglutarate, and lactate. Plasma succinate to fumarate ratios effectively distinguished tumor-bearing and asymptomatic patients with and without SDHx PV with promising diagnostic performance (areas under the receiver operating characteristic curve 0.86-0.95), although higher levels were noted in individuals with SDHB PV. Metabolites in urine and in peripheral blood mononuclear cell extracts were largely similar between groups. Erythrocytes showed strong metabolic alterations in patients with SDHx PV compared to controls, with 8 of 13 low-molecular organic acids being significantly different (P < .05). The lactate-α-ketoglutarate-ratio of erythrocytes identified individuals with SDHx PV equally well as plasma, with a sensitivity and specificity of 92% (AUC 0.97). Blood biomarkers have been underutilized for identifying carriers of SDHx PV or to validate variants of unknown significance. Our findings advocate for further investigation into a combined approach involving plasma and erythrocytes for future diagnostic strategies.

Attenuated frontotemporal brain activation during cognitive tasks is associated with lower succinate dehydrogenase protein levels in patients with major depressive disorder

BackgroundPrevious studies have shown a lower hemodynamic response in patients with major depressive disorder (MDD) during cognitive tasks. However, the mechanism underlying impaired hemodynamic and neural responses to cognitive tasks in MDD patients remains unclear. Succinate dehydrogenase (SDH) is a key biomarker of mitochondrial energy generation, and it can affect the hemodynamic response via the neurovascular coupling effect. In the current study, cerebral hemodynamic responses were detected during verbal fluency tasks (VFTs) via functional near-infrared spectroscopy (fNIRS) and SDH protein levels were examined in serum from MDD patients to quickly identify whether these hemodynamic alterations were related to mitochondrial energy metabolism. MethodsFifty patients with first-episode drug-naïve MDD and 42 healthy controls (HCs) were recruited according to inclusion and exclusion criteria. The 17-item Hamilton Depression Rating Scale (17-HDRS), Hamilton Anxiety Rating Scale (HAMA) and Inventory of Depressive Symptomatology-Self Report (IDS-SR) were used to assess the clinical symptoms of the patients. All participants underwent fNIRS measurements to evaluate cerebral hemodynamic responses in the frontal and temporal cortex during VFTs; moreover, SDH protein levels were measured using an enzyme-linked immunosorbent assay. ResultsActivation in the frontal-temporal brain region during the VFTs was lower in patients with MDD than in HCs. The SDH level in the serum of MDD patients was also significantly lower than that in HCs (p = 0.003), which significantly affected right lateral frontal (p = 0.025) and right temporal (p = 0.022) lobe activation. Both attenuated frontal-temporal activation during the VFTs (OR = 1.531) and lower SDH levels (OR = 1.038) were risk factors for MDD. ConclusionsMDD patients had lower cerebral hemodynamic responses to VFTs; this was associated with mitochondrial dysfunction, as indicated by SDH protein levels. Furthermore, attenuated hemodynamic responses in frontotemporal regions and lower SDH levels increased the risk for MDD. LimitationsThe sample size is relatively small. SDH protein levels in peripheral blood may not necessarily reflect mitochondrial energy generation in the central nervous system.

Discovery of Novel Acethydrazide-Containing Flavonol Derivatives as Potential Antifungal Agents.

In this study, a series of novel hydrazide-containing flavonol derivatives was designed, synthesized, and evaluated for antifungal activity. In the in vitro antifungal assay, most of the target compounds exhibited potent antifungal activity against seven tested phytopathogenic fungi. In particular, compound C32 showed the best antifungal activity against Rhizoctonia solani (EC50 = 0.170 μg/mL), outperforming carbendazim (EC50 = 0.360 μg/mL) and boscalid (EC50 = 1.36 μg/mL). Compound C24 exhibited excellent antifungal activity against Valsa mali, Botrytis cinerea, and Alternaria alternata with EC50 values of 0.590, 0.870, and 1.71 μg/mL, respectively. The in vivo experiments revealed that compounds C32 and C24 were potential novel agricultural antifungals. 3D quantitative structure-activity relationship (3D-QSAR) models were used to analyze the structure-activity relationships of these compounds. The analysis results indicated that introducing appropriate electronegative groups at position 4 of a benzene ring could effectively improve the anti-R. solani activity. In the antifungal mechanism study, scanning electron microscopy and transmission electron microscopy analyses revealed that C32 disrupted the normal growth of hyphae by affecting the structural integrity of the cell membrane and cellular respiration. Furthermore, compound C32 exhibited potent succinate dehydrogenase (SDH) inhibitory activity (IC50 = 8.42 μM), surpassing that of the SDH fungicide boscalid (IC50 = 15.6 μM). The molecular dynamics simulations and docking experiments suggested that compound C32 can occupy the active site and form strong interactions with the key residues of SDH. Our findings have great potential for aiding future research on plant disease control in agriculture.

Intramuscular administration of fractalkine modulates mitochondrial properties and promotes fast glycolytic phenotype.

A newly categorized myokine called fractalkine (CX3CL1) has been associated with divergent conditions such as obesity, tissue inflammation, and exercise. CX3CL1 works through specific membrane-bound receptors (CX3CR1) found in various tissues including skeletal muscles. Studies indicate CX3CL1 induces muscles to uptake energy substrates thereby improving glucose utilization and countering diabetes. Here, we tested if the administration of purified CX3CL1 directly into mice skeletal muscles affects its histoarchitecture, mitochondrial activity, and expression of metabolic proteins. We analyzed four muscles: two upper-limb (quadriceps, hamstrings) and two lower-limb (tibialis anterior, gastrocnemius), contralateral leg muscles were taken as controls. The effects of CX3CL1 treatment on histoarchitecture, mitochondrial activity, and expression of metabolic proteins in muscles were characterized. We used histochemical staining succinate dehydrogenase (SDH)/cytochrome c oxidase (COX), myosin ATPase, alkaline phosphatase (ALP) to evaluate the mitochondrial activity, fiber types, and vascularization in the muscles, respectively. Western blotting was used to evaluate the expression of proteins associated with mitochondrial metabolism (OXPHOS), glycolysis, and vascularization. Overall, this study indicates CX3CL1 primarily modulates mitochondrial metabolism and shifts substrate preference toward glucose in the skeletal muscle. Evidence also supports that CX3CL1 stimulates the relative composition of fast fiber types, influencing selection of energy substrates in the skeletal muscle.

Exploring SDHI fungicide resistance in Botrytis cinerea through genetic transformation system and AlphaFold model-based molecular docking.

Gray mold caused by Botrytis cinerea is one of the most serious diseases affecting strawberry. Succinate dehydrogenase inhibitor (SDHI) fungicides have been used for more than a decade to control the disease. Monitoring resistance and improving in-depth understanding of resistance mechanisms are essential for the control of B. cinerea. In this study, resistance monitoring of a SDHI fungicide boscalid was conducted on B. cinerea isolated from strawberries in Korea during 2020 and 2021, with resistance rates of 76.92% and 72.25%, respectively. In resistant strains, mutations P225F/H and H272R were found in SdhB, with P225F representing the dominant mutation type. Simultaneous mutations G85A, I93V, M158V, and V168I in SdhC were detected in 54.84% of sensitive strains. Sensitivity profiles of different Sdh genotypes of B. cinerea strains to six SDHIs were determined in vitro and in vivo. In addition, the mutation(s) were genetically validated through in situ SdhB (SdhC) expression. Docking assays between SDHIs and AlphaFold model-based Sdh complexes revealed generally consistent patterns with their in vitro phenotypes. Resistance of B. cinerea to SDHI fungicide on strawberry was systematically investigated in this study. Deciphering of SDHI resistance through the genetic transformation system and AlphaFold model-based molecular docking will provide valuable insights into other target site-based fungicide resistance in fungal pathogens. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Cumulative dietary risk assessment for French consumers exposed to succinate dehydrogenase inhibitor pesticides

Consumers are exposed to succinate dehydrogenase inhibitor (SDHI) pesticides through their diet. A cumulative dietary risk assessment for the French population has been performed with French monitoring data (2017–2021) and consumption data from INCA3. The calculation followed a two-tiered approach, using deterministic then probabilistic methods. It was carried out, using European health based guidance values (HBGV) derived for each active substance to characterise their toxicity. In Tier I, the calculated hazard index of 0.12 was below the threshold of 1 and in Tier II, the total margin of exposure at percentile 99.9 remains above the trigger value of 100 (1798 [1631–2311]). In Tier II, the three main risk drivers identified at the upper tail of the distribution were strawberries-fluopyram (19.1%), peaches-fluopyram (14.1%) and table grapes-boscalid (10.5%). Finally, the impact of the major sources of uncertainties was qualitatively evaluated. All together, they were considered of low impact on the outcomes. This work demonstrates the absence of unacceptable chronic risk related to the cumulative exposure of SDHI for French consumers during the 2017–2021 period.

Mouse developmental defects, but not paraganglioma tumorigenesis, upon conditional Complex II loss in early Sox10+ cells.

In humans, loss of heterozygosity for defective alleles of any of the four subunits of mitochondrial tricarboxylic acid cycle enzyme succinate dehydrogenase (SDH, also Complex II of the electron transport chain) can lead to paraganglioma tumors in neuroendocrine cells. With the goal of developing mouse models of this rare disorder, we have developed various SDH conditional loss strategies. Based on recent lineage tracing studies, we hypothesized that conditional SDHC loss in early embryogenesis during migration of primordial neural crest cells that form the susceptible chromaffin cells of the adrenal medulla might induce paraganglioma. We triggered low levels of detectable SDHC loss in Sox10+ cells at E11.5 of mouse development. We report that, rather than developing adrenal medulla paraganglioma (pheochromocytoma), offspring survived with evidence of neural crest cell dysfunction. Phenotypes included mild lower extremity gait anomalies suggestive of neural tube closure defects and patches of unpigmented fur consistent with neural crest-derived melanocyte dysfunction. These defects were not observed in mice lacking Sdhc knockout. Our results add to existing data suggesting that, unlike humans, even early embryonic (Sox10-driven) SDHx loss is inadequate to trigger paraganglioma in mice of the genetic backgrounds that have been investigated. Instead, low levels of tricarboxylic acid cycle-deficient neural crest cells cause mild developmental defects in hind limb and melanocyte function. This new model may be of interest for studies of metabolism during early neural crest cell development.

Discovery, Optimization, and Biological Evaluation of Novel Pyrazol-5-yl-phenoxybenzamide Derivatives as Potent Succinate Dehydrogenase Inhibitors.

The diphenyl ether molecular pharmacophore has played a significant role in the development of fungicidal compounds. In this study, a variety of pyrazol-5-yl-phenoxybenzamide derivatives were synthesized and evaluated for their potential to act as succinate dehydrogenase inhibitors (SDHIs). The bioassay results indicate certain compounds to display a remarkable and broad-spectrum in their antifungal activities. Notably, compound 12x exhibited significant in vitro activities against Valsa mali, Gaeumannomyces graminis, and Botrytis cinerea, with EC50 values of 0.52, 1.46, and 3.42 mg/L, respectively. These values were lower or comparable to those of Fluxapyroxad (EC50 = 12.5, 1.93, and 8.33 mg/L, respectively). Additionally, compound 12x showed promising antifungal activities against Sclerotinia sclerotiorum (EC50 = 0.82 mg/L) and Rhizoctonia solani (EC50 = 1.86 mg/L), albeit lower than Fluxapyroxad (EC50 = 0.23 and 0.62 mg/L). Further in vivo experiments demonstrated compound 12x to possess effective protective antifungal activities against V. mali and S. sclerotiorum at a concentration of 100 mg/L, with inhibition rates of 66.7 and 89.3%, respectively. In comparison, Fluxapyroxad showed inhibition rates of 29.2 and 96.4% against V. mali and S. sclerotiorum, respectively. Molecular docking analysis revealed that compound 12x interacts with SDH through hydrogen bonding, π-cation, and π-π interactions, providing insights into the probable mechanism of action. Furthermore, compound 12x exhibited greater binding energy and SDH enzyme inhibitory activity than Fluxapyroxad (ΔGcal = -46.8 kcal/mol, IC50 = 1.22 mg/L, compared to ΔGcal = -41.1 kcal/mol, IC50 = 8.32 mg/L). Collectively, our results suggest that compound 12x could serve as a promising fungicidal lead compound for the development of more potent SDHIs for crop protection.

Genotype Phenotype Correlation of Renal Tumors in the Cancer Genome Atlas Database.

Morphological features are critical in evaluation of renal tumors and directing molecular workup. The objective of this study was to review histomorphology of renal tumors with molecular alterations of known subtypes. Renal tumors in The Cancer Genome Atlas were reviewed to identify tumors with defining molecular alterations. Single representative digital slides and pathology reports were reviewed and morphologic features recorded. Sixty tumors were identified with molecular alterations in genes characteristic of defined renal cell carcinoma (RCC) subtypes. Findings included the presence of both low- and high-grade histology in TFE3 rearranged RCCs, TFEB amplified RCCs, succinate dehydrogenase (SDH) mutated RCCs and RCCs with mutations in mismatch repair genes. Three ELOC mutated RCCs were identified, one of which demonstrated infiltrative features. Pseudostratification of nuclei in fumarate hydratase mutated RCCs and nuclear grooves in SDH mutated RCCs were intriguing findings not previously reported. Mucinous features were noted in NF2, KRAS, and SDH mutated and ALK rearranged tumors. Significant morphologic overlap was noted across most categories with limited clues for subclassification. Whereas the number of diagnostic entities for kidney tumors continues to increase, many of these have overlapping features, highlighting the significant role molecular characterization currently plays and will continue to play in the future.

Astroglial membrane camouflaged Ptbp1 siRNA delivery hinders glutamate homeostasis via SDH/Nrf2 pathway

Polypyrimidine tract-binding protein 1 (PTBP1) regulates numerous alternative splicing events during tumor progression and neurogenesis. Previously, PTBP1 downregulation was reported to convert astrocytes into functional neurons; however, how PTBP1 regulates astrocytic physiology remains unclear. In this study, we revealed that PTBP1 modulated glutamate uptake via ATP1a2, a member of Na+/K+-ATPases, and glutamate transporters in astrocytes. Ptbp1 knockdown altered mitochondrial function and energy metabolism, which involved PTBP1 regulating mitochondrial redox homeostasis via the succinate dehydrogenase (SDH)/Nrf2 pathway. The malfunction of glutamate transporters following Ptbp1 knockdown resulted in enhanced excitatory synaptic transmission in the cortex. Notably, we developed a biomimetic cationic triblock polypeptide system, i.e., polyethylene glycol44-polylysine30-polyleucine10 (PEG44-PLL30-PLLeu10) with astrocytic membrane coating to deliver Ptbp1 siRNA in vitro and in vivo, which approach allowed Ptbp1 siRNA to efficiently cross the blood-brain barrier and target astrocytes in the brain. Collectively, our findings suggest a framework whereby PTBP1 serves as a modulator in glutamate transport machinery, and indicate that biomimetic methodology is a promising route for in vivo siRNA delivery.

Design, synthesis and biological activity evaluation of eco-friendly rosin-based fungicides for sustainable crop protection.

Utilizing fungicides to protect crops from diseases is an effective method, and novel eco-friendly plant-derived fungicides with high efficiency and low toxicity are urgent requirements for sustainable crop protection. Two series of rosin-based fungicides (totally 35) were designed and synthesized. In vitro fungicidal activity revealed that Compound 6a (Co. 6a) effectively inhibited the growth of Valsa mali [median effective concentration (EC50) = 0.627 μg mL-1], and in vivo fungicidal activity suggested a significant protective efficacy of Co. 6a in protecting both apple branches (35.12% to 75.20%) and apples (75.86% to 90.82%). Quantum chemical calculations (via density functional theory) results indicated that the primary active site of Co. 6a lies in its amide structure. Mycelial morphology and physiology were investigated to elucidate the mode-of-action of Co. 6a, and suggested that Co. 6a produced significant cell membrane damage, accelerated electrolyte leakage, decreased succinate dehydrogenase (SDH) protein activity, and impaired physiological and biochemical functions, culminating in mycelial mortality. Molecular docking analysis revealed a robust binding energy (ΔE = -7.29 kcal mol-1) between Co. 6a and SDH. Subsequently, biosafety evaluations confirmed the environmentally-friendly nature of Co. 6a via the zebrafish model, yet toxicological results indicated that Co. 6a at median lethal concentration [LC50(96)] damaged the gills, liver and intestines of zebrafish. The above research offers a theoretical foundation for exploiting eco-friendly rosin-based fungicidal candidates in sustainable crop protection. © 2024 Society of Chemical Industry.