Pub Date : 2025-12-01Epub Date: 2025-09-12DOI: 10.1016/j.niox.2025.09.003
Brenda da Silva , Fernanda Tibolla Viero , Caren Tatiane de David Antoniazzi , Sabrina Qader Kudsi , Diulle Spat Peres , Ricardo Iuri Felix Morais , Leonardo Gomes Pereira , Gabriela Trevisan
Multiple sclerosis (MS) is a complex neuroinflammatory disease often associated with migraine and anxiety, both of which impair quality of life. MS pathology involves intense inflammatory and oxidative processes, including increased nitric oxide (NO) production. However, the role of NO in MS-related migraine symptoms remains unclear. This study evaluated whether repeated administration of 7-nitroindazole (7-NI), a selective neuronal nitric oxide synthase (nNOS) inhibitor, could alleviate migraine-like nociception, anxiety-like behavior, and neuroinflammatory biomarkers in a relapsing-remitting experimental autoimmune encephalomyelitis (RR-EAE) mouse model. RR-EAE was induced in female C57BL/6 mice (20–30 g) using myelin oligodendrocyte glycoprotein (MOG35-55) and Quillaja saponin as an adjuvant. Mice received daily intragastric 7-NI (120 mg/kg) from day 20–35 post-induction. Disease progression, mechanical/spontaneous allodynia, and anxiety-like behavior were assessed. At the end of the protocol, oxidative and inflammatory biomarkers were analyzed. 7-NI treatment significantly reduced disease severity and nociception, exerted an anxiolytic effect, and improved myelin quality parameters. It inhibited the increase of oxidative and nitrosative markers (NOx, H2O2) in the brainstem, trigeminal ganglion, and plasma. Treatment also prevented plasma calcitonin gene-related peptide elevation and increased anti-inflammatory cytokines (IL-4, IL-10), suggesting positive modulation of neuroinflammation in RR-EAE. These findings highlight the therapeutic potential of 7-NI in MS; however, further studies are required to confirm its safety and efficacy in different populations and chronic disease contexts.
{"title":"7-Nitroindazole, an nNOS inhibitor, reduces migraine-like nociception, demyelination, and anxiety-like behavior in a mouse model of relapsing-remitting multiple sclerosis","authors":"Brenda da Silva , Fernanda Tibolla Viero , Caren Tatiane de David Antoniazzi , Sabrina Qader Kudsi , Diulle Spat Peres , Ricardo Iuri Felix Morais , Leonardo Gomes Pereira , Gabriela Trevisan","doi":"10.1016/j.niox.2025.09.003","DOIUrl":"10.1016/j.niox.2025.09.003","url":null,"abstract":"<div><div>Multiple sclerosis (MS) is a complex neuroinflammatory disease often associated with migraine and anxiety, both of which impair quality of life. MS pathology involves intense inflammatory and oxidative processes, including increased nitric oxide (NO) production. However, the role of NO in MS-related migraine symptoms remains unclear. This study evaluated whether repeated administration of 7-nitroindazole (7-NI), a selective neuronal nitric oxide synthase (nNOS) inhibitor, could alleviate migraine-like nociception, anxiety-like behavior, and neuroinflammatory biomarkers in a relapsing-remitting experimental autoimmune encephalomyelitis (RR-EAE) mouse model. RR-EAE was induced in female C57BL/6 mice (20–30 g) using myelin oligodendrocyte glycoprotein (MOG35-55) and Quillaja saponin as an adjuvant. Mice received daily intragastric 7-NI (120 mg/kg) from day 20–35 post-induction. Disease progression, mechanical/spontaneous allodynia, and anxiety-like behavior were assessed. At the end of the protocol, oxidative and inflammatory biomarkers were analyzed. 7-NI treatment significantly reduced disease severity and nociception, exerted an anxiolytic effect, and improved myelin quality parameters. It inhibited the increase of oxidative and nitrosative markers (NOx, H<sub>2</sub>O<sub>2</sub>) in the brainstem, trigeminal ganglion, and plasma. Treatment also prevented plasma calcitonin gene-related peptide elevation and increased anti-inflammatory cytokines (IL-4, IL-10), suggesting positive modulation of neuroinflammation in RR-EAE. These findings highlight the therapeutic potential of 7-NI in MS; however, further studies are required to confirm its safety and efficacy in different populations and chronic disease contexts.</div></div>","PeriodicalId":19357,"journal":{"name":"Nitric oxide : biology and chemistry","volume":"159 ","pages":"Pages 51-62"},"PeriodicalIF":3.2,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145065441","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01Epub Date: 2025-09-06DOI: 10.1016/j.niox.2025.09.001
Dong Ding , Ran Tian , Xiao Yang , Zhe Ren , Zhi-Cheng Jing , Xin-Tong Wu , Lian-Wen Sun
{"title":"Corrigendum to “The impact of ciliary length on the mechanical response of osteocytes to fluid shear stress” [Nitric Oxide 155 2025 1–11]","authors":"Dong Ding , Ran Tian , Xiao Yang , Zhe Ren , Zhi-Cheng Jing , Xin-Tong Wu , Lian-Wen Sun","doi":"10.1016/j.niox.2025.09.001","DOIUrl":"10.1016/j.niox.2025.09.001","url":null,"abstract":"","PeriodicalId":19357,"journal":{"name":"Nitric oxide : biology and chemistry","volume":"159 ","pages":"Pages 38-39"},"PeriodicalIF":3.2,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145004508","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01Epub Date: 2025-10-01DOI: 10.1016/j.niox.2025.09.006
Handan Gunes, Ercan Ozdemir, Ahmet Sevki Taskiran
Epilepsy is a disease affecting the quality of life, characterized by neuronal excessive discharges resulting from the disruption of the balance between excitatory and inhibitory systems in the brain, and its pathophysiology has not been fully elucidated. In this study, we investigated the effects of serotonin 7 (5-HT7) receptor antagonist SB 269970 on seizures in a pentylenetetrazol (PTZ)-induced epilepsy model. Seventy male Wistar Albino rats (weight 230–250 g) were used in the study and the rats were randomly assigned to control and drug groups. Predetermined doses of SB 269970 (3 mg/kg), 5-HT7 agonist AS 19 (5 mg/kg), 7-NI (nNOS inhibitor, 50 mg/kg), YC-1 (guanylate cyclase activator, 10 μg/kg) were administered to the rats. PTZ (35 mg/kg) was injected intraperitoneally to induce seizures. The Racine scale was used to evaluate seizure stages. After electrocorticography (ECoG) and video recordings, the rats were sacrificed and nitric oxide (NO), cGMP, nNOS and proinflammatory cytokines (TNF-α, IL-1β and IL-6) levels in hippocampal tissue were measured by biochemical methods. The study results showed that the seizure threshold increased and the number of seizures decreased in rats administered SB 269970. In addition, the levels of proinflammatory cytokines (TNF-α, IL-6, IL-1β) and NO, cGMP and nNOS, which are increased with seizures in the hippocampal tissue, were significantly decreased by the administration of SB 269970. In contrast, the administration of 5-HT7 agonist AS-19 increased the number of seizures and caused an increase in the levels of hippocampal proinflammatory cytokines and NO, cGMP and nNOS. In conclusion, the findings of this study revealed that SB 269970 causes anticonvulsant activity by inhibiting the NO/cGMP pathway and proinflammatory cytokine (TNF-α, IL-1β and IL-6) levels in the hippocampal tissue. However, further molecular studies are needed for 5-HT7 antagonist drugs to be an option in the treatment of epilepsy.
{"title":"5-HT7 receptor antagonist SB269970 attenuates seizures by modulating NO/cGMP signaling pathway and neuroinflammation in a pentylenetetrazol-induced epilepsy model in rats","authors":"Handan Gunes, Ercan Ozdemir, Ahmet Sevki Taskiran","doi":"10.1016/j.niox.2025.09.006","DOIUrl":"10.1016/j.niox.2025.09.006","url":null,"abstract":"<div><div>Epilepsy is a disease affecting the quality of life, characterized by neuronal excessive discharges resulting from the disruption of the balance between excitatory and inhibitory systems in the brain, and its pathophysiology has not been fully elucidated. In this study, we investigated the effects of serotonin 7 (5-HT7) receptor antagonist SB 269970 on seizures in a pentylenetetrazol (PTZ)-induced epilepsy model. Seventy male Wistar Albino rats (weight 230–250 g) were used in the study and the rats were randomly assigned to control and drug groups. Predetermined doses of SB 269970 (3 mg/kg), 5-HT7 agonist AS 19 (5 mg/kg), 7-NI (nNOS inhibitor, 50 mg/kg), YC-1 (guanylate cyclase activator, 10 μg/kg) were administered to the rats. PTZ (35 mg/kg) was injected intraperitoneally to induce seizures. The Racine scale was used to evaluate seizure stages. After electrocorticography (ECoG) and video recordings, the rats were sacrificed and nitric oxide (NO), cGMP, nNOS and proinflammatory cytokines (TNF-α, IL-1β and IL-6) levels in hippocampal tissue were measured by biochemical methods. The study results showed that the seizure threshold increased and the number of seizures decreased in rats administered SB 269970. In addition, the levels of proinflammatory cytokines (TNF-α, IL-6, IL-1β) and NO, cGMP and nNOS, which are increased with seizures in the hippocampal tissue, were significantly decreased by the administration of SB 269970. In contrast, the administration of 5-HT7 agonist AS-19 increased the number of seizures and caused an increase in the levels of hippocampal proinflammatory cytokines and NO, cGMP and nNOS. In conclusion, the findings of this study revealed that SB 269970 causes anticonvulsant activity by inhibiting the NO/cGMP pathway and proinflammatory cytokine (TNF-α, IL-1β and IL-6) levels in the hippocampal tissue. However, further molecular studies are needed for 5-HT7 antagonist drugs to be an option in the treatment of epilepsy.</div></div>","PeriodicalId":19357,"journal":{"name":"Nitric oxide : biology and chemistry","volume":"159 ","pages":"Pages 78-88"},"PeriodicalIF":3.2,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145220300","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01Epub Date: 2025-10-06DOI: 10.1016/j.niox.2025.10.004
Yali Qiao , Yayu Liu , Jihua Yu , Weibiao Liao
Postharvest quality maintenance is a key research focus in horticultural science. Nitric oxide (NO), a vital gaseous signaling molecule, significantly improves postharvest quality by inhibiting ethylene (ETH) synthesis, reducing respiration rate, enhancing antioxidant enzyme systems, maintaining cell wall integrity, and regulating secondary metabolism. Currently, the synergistic mechanisms between NO and hydrogen sulfide (H2S) have emerged as a research hotspot. The two molecules work in concert to delay postharvest senescence and enhance fruit resistance to low temperature and pathogens involving enzyme activity regulation and physiological synergy. This review provides a comprehensive analysis of the independent regulatory effects of NO and its crosstalk mechanisms with H2S, providing theoretical foundations for developing efficient and safe postharvest preservation technologies and highlighting their potential applications in green preservation.
{"title":"Roles of nitric oxide in improving post-harvest horticultural product quality: Crosstalk with hydrogen sulfide","authors":"Yali Qiao , Yayu Liu , Jihua Yu , Weibiao Liao","doi":"10.1016/j.niox.2025.10.004","DOIUrl":"10.1016/j.niox.2025.10.004","url":null,"abstract":"<div><div>Postharvest quality maintenance is a key research focus in horticultural science. Nitric oxide (NO), a vital gaseous signaling molecule, significantly improves postharvest quality by inhibiting ethylene (ETH) synthesis, reducing respiration rate, enhancing antioxidant enzyme systems, maintaining cell wall integrity, and regulating secondary metabolism. Currently, the synergistic mechanisms between NO and hydrogen sulfide (H<sub>2</sub>S) have emerged as a research hotspot. The two molecules work in concert to delay postharvest senescence and enhance fruit resistance to low temperature and pathogens involving enzyme activity regulation and physiological synergy. This review provides a comprehensive analysis of the independent regulatory effects of NO and its crosstalk mechanisms with H<sub>2</sub>S, providing theoretical foundations for developing efficient and safe postharvest preservation technologies and highlighting their potential applications in green preservation.</div></div>","PeriodicalId":19357,"journal":{"name":"Nitric oxide : biology and chemistry","volume":"159 ","pages":"Pages 102-114"},"PeriodicalIF":3.2,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145252167","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01Epub Date: 2025-10-05DOI: 10.1016/j.niox.2025.10.001
Sajad Jeddi , Khosrow Kashfi , Asghar Ghasemi
Diabetic nephropathy (DN) is characterized by structural kidney alterations—including glomerular basement membrane thickening, mesangial expansion, tubulointerstitial fibrosis, and glomerular hypertrophy—alongside functional impairments such as reduced glomerular filtration rate (GFR) and albuminuria. DN progresses through five stages: pre-nephropathy, silent, incipient, overt nephropathy, and end-stage kidney disease (ESKD). Dysregulation of the nitric oxide synthase (NOS) pathway—including neuronal NOS (nNOS), inducible NOS (iNOS), and endothelial NOS (eNOS)—has been increasingly implicated in DN pathogenesis. Evidence from preclinical models using NOS inhibitors and knockout mice, combined with human studies that identify NOS gene polymorphisms, supports this association. In early stages, hyperglycemia elevates GFR, driven by increased NO production from all three NOS isoforms. As the disease progresses, reduced eNOS-derived NO and persistent iNOS overexpression contribute to structural damage and a decline in GFR. NO donors have been shown to prevent early hyperfiltration and attenuate the subsequent decrease in GFR and renal injury characteristic of overt nephropathy. Thus, NO signaling plays a dual role in DN progression and represents a promising target for therapeutic intervention.
{"title":"Diabetic nephropathy: Role of nitric oxide","authors":"Sajad Jeddi , Khosrow Kashfi , Asghar Ghasemi","doi":"10.1016/j.niox.2025.10.001","DOIUrl":"10.1016/j.niox.2025.10.001","url":null,"abstract":"<div><div>Diabetic nephropathy (DN) is characterized by structural kidney alterations—including glomerular basement membrane thickening, mesangial expansion, tubulointerstitial fibrosis, and glomerular hypertrophy—alongside functional impairments such as reduced glomerular filtration rate (GFR) and albuminuria. DN progresses through five stages: pre-nephropathy, silent, incipient, overt nephropathy, and end-stage kidney disease (ESKD). Dysregulation of the nitric oxide synthase (NOS) pathway—including neuronal NOS (nNOS), inducible NOS (iNOS), and endothelial NOS (eNOS)—has been increasingly implicated in DN pathogenesis. Evidence from preclinical models using NOS inhibitors and knockout mice, combined with human studies that identify NOS gene polymorphisms, supports this association. In early stages, hyperglycemia elevates GFR, driven by increased NO production from all three NOS isoforms. As the disease progresses, reduced eNOS-derived NO and persistent iNOS overexpression contribute to structural damage and a decline in GFR. NO donors have been shown to prevent early hyperfiltration and attenuate the subsequent decrease in GFR and renal injury characteristic of overt nephropathy. Thus, NO signaling plays a dual role in DN progression and represents a promising target for therapeutic intervention.</div></div>","PeriodicalId":19357,"journal":{"name":"Nitric oxide : biology and chemistry","volume":"159 ","pages":"Pages 89-101"},"PeriodicalIF":3.2,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145244776","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01Epub Date: 2025-10-05DOI: 10.1016/j.niox.2025.10.002
Zahra Bahadoran , Asghar Ghasemi
Diabetic peripheral neuropathy (DPN) is one of the most prevalent long-term complications in type 1 (T1DM) and type 2 (T2DM) diabetes mellitus and is characterized by structural (microangiopathy, axonal atrophy, impaired myelination, and disrupted Schwann cell-axon interactions) and functional (impaired axonal transport and sensory and motor disorders) changes in neurons. Nitric oxide (NO) contributes to the development and progression of DPN as it has a role in the perfusion and electrophysiological functions of neurons. NO is essential for sustaining nerve conduction velocity (NCV) through modulation of Na+/K+-ATPase activity. Isoform-specific alterations in NO synthase (NOS) expression and activity occur during the development of DPN. Neural NOS (nNOS) generally exhibits consistent downregulation, especially in T2DM models, whereas inducible NOS (iNOS) tends to be upregulated in the T1DM model. NO has been proposed as a potential therapeutic agent for DPN because of its potent vasodilatory effects. NO-donating derivatives (e.g., NCX1404, PRG150) have demonstrated both symptomatic and disease-modifying effects in DPN. In conclusion, NO plays a role in the pathophysiology of DPN and is a therapeutic target for managing neuropathy in diabetes.
{"title":"Diabetic peripheral neuropathy: Role of nitric oxide","authors":"Zahra Bahadoran , Asghar Ghasemi","doi":"10.1016/j.niox.2025.10.002","DOIUrl":"10.1016/j.niox.2025.10.002","url":null,"abstract":"<div><div>Diabetic peripheral neuropathy (DPN) is one of the most prevalent long-term complications in type 1 (T1DM) and type 2 (T2DM) diabetes mellitus and is characterized by structural (microangiopathy, axonal atrophy, impaired myelination, and disrupted Schwann cell-axon interactions) and functional (impaired axonal transport and sensory and motor disorders) changes in neurons. Nitric oxide (NO) contributes to the development and progression of DPN as it has a role in the perfusion and electrophysiological functions of neurons. NO is essential for sustaining nerve conduction velocity (NCV) through modulation of Na<sup>+</sup>/K<sup>+</sup>-ATPase activity. Isoform-specific alterations in NO synthase (NOS) expression and activity occur during the development of DPN. Neural NOS (nNOS) generally exhibits consistent downregulation, especially in T2DM models, whereas inducible NOS (iNOS) tends to be upregulated in the T1DM model. NO has been proposed as a potential therapeutic agent for DPN because of its potent vasodilatory effects. NO-donating derivatives (e.g., NCX1404, PRG150) have demonstrated both symptomatic and disease-modifying effects in DPN. In conclusion, NO plays a role in the pathophysiology of DPN and is a therapeutic target for managing neuropathy in diabetes.</div></div>","PeriodicalId":19357,"journal":{"name":"Nitric oxide : biology and chemistry","volume":"159 ","pages":"Pages 147-160"},"PeriodicalIF":3.2,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145244786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01Epub Date: 2025-09-05DOI: 10.1016/j.niox.2025.09.002
Laxman Poudel , Thilini Karunarathna , Stephen Baker , Elmira Alipour , Matthew R. Dent , Jesús Tejero , Mark T. Gladwin , Anthony W. DeMartino , Daniel B. Kim-Shapiro
We recently demonstrated a rapid reaction between labile ferric heme and nitric oxide (NO) in the presence of reduced glutathione (GSH) or other small thiols in a process called thiol-catalyzed reductive nitrosylation, yielding a novel signaling molecule, labile nitrosyl ferrous heme (NO-ferroheme), which we and others have shown can regulate vasodilation and platelet homeostasis. Red blood cells (RBCs) contain high concentrations of GSH, and NO can be generated in the RBC via nitrite reduction and/or RBC endothelial nitric oxide synthase (eNOS) so that NO-ferroheme could, in principle, be formed in the RBC. NO-ferroheme may also form in other cells and compartments, including in plasma, where another small and reactive thiol species, hydrogen sulfide (H2S/HS−), is also present and may catalyze NO-ferroheme formation akin to GSH. Here, we compare the reactivity of GSH and hydrogen sulfide with hemin in physiologically relevant media, including human serum albumin (HSA) and RBC membranes. Strikingly, hydrogen sulfide demonstrated a second-order rate constant over 10 times higher than GSH. We propose that the increased solubility of H2S vs GSH in lipophilic environments – where labile heme is most readily found – and the increased steric hindrance of the bulkier GSH account for the faster reaction kinetics observed with hydrogen sulfide. Our findings suggest that the hydrogen sulfide-catalyzed reductive nitrosylation reaction produces thionitrous acid (HSNO), which readily undergoes further reactions with excess hydrogen sulfide to form nitrosopersulfide (SSNO−) and polysulfides. These results suggest a common theme in thiol-catalyzed reductive nitrosylation of labile ferric heme that could play an important role in NO signaling.
{"title":"Role of hydrogen sulfide in catalyzing the formation of NO-ferroheme","authors":"Laxman Poudel , Thilini Karunarathna , Stephen Baker , Elmira Alipour , Matthew R. Dent , Jesús Tejero , Mark T. Gladwin , Anthony W. DeMartino , Daniel B. Kim-Shapiro","doi":"10.1016/j.niox.2025.09.002","DOIUrl":"10.1016/j.niox.2025.09.002","url":null,"abstract":"<div><div>We recently demonstrated a rapid reaction between labile ferric heme and nitric oxide (NO) in the presence of reduced glutathione (GSH) or other small thiols in a process called thiol-catalyzed reductive nitrosylation, yielding a novel signaling molecule, labile nitrosyl ferrous heme (NO-ferroheme), which we and others have shown can regulate vasodilation and platelet homeostasis. Red blood cells (RBCs) contain high concentrations of GSH, and NO can be generated in the RBC via nitrite reduction and/or RBC endothelial nitric oxide synthase (eNOS) so that NO-ferroheme could, in principle, be formed in the RBC. NO-ferroheme may also form in other cells and compartments, including in plasma, where another small and reactive thiol species, hydrogen sulfide (H<sub>2</sub>S/HS<sup>−</sup>), is also present and may catalyze NO-ferroheme formation akin to GSH. Here, we compare the reactivity of GSH and hydrogen sulfide with hemin in physiologically relevant media, including human serum albumin (HSA) and RBC membranes. Strikingly, hydrogen sulfide demonstrated a second-order rate constant over 10 times higher than GSH. We propose that the increased solubility of H<sub>2</sub>S vs GSH in lipophilic environments – where labile heme is most readily found – and the increased steric hindrance of the bulkier GSH account for the faster reaction kinetics observed with hydrogen sulfide. Our findings suggest that the hydrogen sulfide-catalyzed reductive nitrosylation reaction produces thionitrous acid (HSNO), which readily undergoes further reactions with excess hydrogen sulfide to form nitrosopersulfide (SSNO<sup>−</sup>) and polysulfides. These results suggest a common theme in thiol-catalyzed reductive nitrosylation of labile ferric heme that could play an important role in NO signaling.</div></div>","PeriodicalId":19357,"journal":{"name":"Nitric oxide : biology and chemistry","volume":"159 ","pages":"Pages 40-50"},"PeriodicalIF":3.2,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145008359","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Conserved across the phylogeny, S-nitrosylation and S-denitrosylation of biological thiols is a reversible protein post-translational modification of cysteine thiol residues involving nitric oxide (NO) and NO•-derived metabolites. S-nitrosylation of proteins is observed to transduce signalling pathways with significant pathological and physiological relevance. Although endogenous S-nitrosylation is also an obligate non-classical cellular signalling pathway of NO• in single-celled organisms, but very little information is available in prokaryotes. Hitherto unknown, we present experimental evidence for the first time in vivo S-nitrosylation (without using any NO•/RNS donor) of proteins of the enteropathogenic, Gram-negative bacteria O1 El Tor strains of Vibrio cholerae N16961 and C6706. In the present study, PSNO was quantified by 2, 3-diaminonaphthalene (DAN) using a spectrofluorometer, which was further supported by confocal microscopy. Western blot and mass spectrometry-based proteomic analyses identified ten S-nitrosylated proteins via DMPO-nitrone adduct formation. V. cholerae contained high amounts of the in vivo pool of S-nitrosylated proteome in different respiratory conditions. Experimental evidence shows that physiological levels of glutathione (GSH) can efficiently S-denitrosylate Vibrio cholerae PSNO in a concentration-dependent manner, suggesting that the intracellular GSH tends to reset the redox state of these protein thiols. Our data suggests that V. cholerae possesses more amount of in vivo PSNO during semi-anaerobic respiration than aerobic respiration and irrespective of media and strain used; stationary phase cells are relatively more stable to GSH-catalyzed S-denitrosylation than their log-phase counterparts. Additionally, the in vivo PSNO accumulation was found to be elevated in the nitrate reductase deletion mutant (ΔnapA), indicating the role of napA in the nitroso-oxidative stress response mechanism of V. cholerae. This could aid in its remarkable adaptability and survivability in the hostile conditions of the human intestine, thereby paving the way for cholera, a highly contagious diarrheal disease.
{"title":"Detection and proteomic identification of in vivo S-nitrosylated proteins in Vibrio cholerae: A novel evidence","authors":"Shuddhasattwa Samaddar , Surupa Chakraborty , Rajib Sengupta , Sanjay Ghosh","doi":"10.1016/j.niox.2025.09.005","DOIUrl":"10.1016/j.niox.2025.09.005","url":null,"abstract":"<div><div>Conserved across the phylogeny, S-nitrosylation and S-denitrosylation of biological thiols is a reversible protein post-translational modification of cysteine thiol residues involving nitric oxide (NO) and NO<sup>•</sup>-derived metabolites. S-nitrosylation of proteins is observed to transduce signalling pathways with significant pathological and physiological relevance. Although endogenous S-nitrosylation is also an obligate non-classical cellular signalling pathway of NO<sup>•</sup> in single-celled organisms, but very little information is available in prokaryotes. Hitherto unknown, we present experimental evidence for the first time in vivo S-nitrosylation (without using any NO<sup>•</sup>/RNS donor) of proteins of the enteropathogenic, Gram-negative bacteria O1 El Tor strains of <em>Vibrio cholerae</em> N16961 and C6706. In the present study, PSNO was quantified by 2, 3-diaminonaphthalene (DAN) using a spectrofluorometer, which was further supported by confocal microscopy. Western blot and mass spectrometry-based proteomic analyses identified ten S-nitrosylated proteins <em>via</em> DMPO-nitrone adduct formation. <em>V. cholerae</em> contained high amounts of the in vivo pool of S-nitrosylated proteome in different respiratory conditions. Experimental evidence shows that physiological levels of glutathione (GSH) can efficiently S-denitrosylate <em>Vibrio cholerae</em> PSNO in a concentration-dependent manner, suggesting that the intracellular GSH tends to reset the redox state of these protein thiols. Our data suggests that <em>V. cholerae</em> possesses more amount of in vivo PSNO during semi-anaerobic respiration than aerobic respiration and irrespective of media and strain used; stationary phase cells are relatively more stable to GSH-catalyzed S-denitrosylation than their log-phase counterparts. Additionally, the in vivo PSNO accumulation was found to be elevated in the nitrate reductase deletion mutant <em>(</em>Δ<em>napA</em>), indicating the role of <em>napA</em> in the nitroso-oxidative stress response mechanism of <em>V. cholerae</em>. This could aid in its remarkable adaptability and survivability in the hostile conditions of the human intestine, thereby paving the way for cholera, a highly contagious diarrheal disease.</div></div>","PeriodicalId":19357,"journal":{"name":"Nitric oxide : biology and chemistry","volume":"159 ","pages":"Pages 63-77"},"PeriodicalIF":3.2,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145213349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nitrate (NO3−), besides serving as a major N source, also acts as a signalling molecule in plant growth and development. Studies on NO3− dependent regulation of root growth in wheat (Triticum aestivum) are mostly limited to morphophysiological changes, while the underlying signalling mechanisms remain largely unexplored. To bridge this gap, the present study aims to get a mechanistic understanding of the NO3− dependent regulation of root growth in wheat seedlings. For this, uniformly germinated two days old wheat seedlings were exposed to nitric oxide (NO) donor sodium nitroprusside (SNP), auxin source Indole-3-butyric acid (IBA), calcium chloride as source of calcium (Ca2+), NO scavenger 2-4-carboxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO), polar auxin transport inhibitor 2,3,5-triiodobenzoic acid (TIBA) and calcium chelator ethylene glycol-bis (β-aminoethyl ether)-N,N,N′,N'-tetraacetic acid (EGTA) with NO3− as a major determinant. After seven days, root traits were analyzed, and a tissue localization assay was performed using Fluo-3 AM, DAF-FM, and salkowski reagents to visualize the distribution of Ca2+, NO, and indole-3-acetic acid (IAA) in root tissues, respectively. The study reveals that the cross-talk of nitric oxide (NO), auxin and calcium (Ca2+) modulates NO3− regulated root growth in wheat seedlings. The changes in cytosolic Ca2+ concentration ([Ca2+]cyt) are a major mediator in the regulation of root growth. High NO3− (5 mM) in combination with exogenous IBA and Ca2+ suppresses the root growth, with ethylene acting downstream of [Ca2+]cyt. We observed a synergistic effect between NO and endogenous IAA (Indole-3-acetic acid) in lateral root (LR) growth. In LRs, the external NO3− enhances the NO production, which is further augmented by the elevated [Ca2+]cyt levels. Our results indicate that endogenous IAA plays a pivotal role in regulating root hair development on LR with NO and [Ca2+]cyt functioning downstream of the signalling cascade. However, the high NO3− was found to counteract the root hair formation by importing the shoot-derived auxin. These findings provide valuable insights into the intricate signalling interactions between nitric oxide, auxin, and calcium in NO3− regulated root development in wheat, with potential targets for enhancing nutrient uptake efficiency. Further work is necessary to identify downstream signalling components and examine how shoot-to-root signalling modulates the root architectures under different NO3− regimes.
{"title":"Nitrate-dependent changes in the primary and lateral root growth in wheat seedlings require the coordinated action of auxin, calcium and nitric oxide","authors":"Sandeep B. Adavi , Lekshmy Sathee , Rakesh Pandey , Prachi Yadav","doi":"10.1016/j.niox.2025.08.003","DOIUrl":"10.1016/j.niox.2025.08.003","url":null,"abstract":"<div><div>Nitrate (NO<sub>3</sub><sup>−</sup>), besides serving as a major N source, also acts as a signalling molecule in plant growth and development. Studies on NO<sub>3</sub><sup>−</sup> dependent regulation of root growth in wheat (<em>Triticum aestivum</em>) are mostly limited to morphophysiological changes, while the underlying signalling mechanisms remain largely unexplored. To bridge this gap, the present study aims to get a mechanistic understanding of the NO<sub>3</sub><sup>−</sup> dependent regulation of root growth in wheat seedlings. For this, uniformly germinated two days old wheat seedlings were exposed to nitric oxide (NO) donor sodium nitroprusside (SNP), auxin source Indole-3-butyric acid (IBA), calcium chloride as source of calcium (Ca<sup>2+</sup>), NO scavenger 2-4-carboxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO), polar auxin transport inhibitor 2,3,5-triiodobenzoic acid (TIBA) and calcium chelator ethylene glycol-bis (β-aminoethyl ether)-N,N,N′,N'-tetraacetic acid (EGTA) with NO<sub>3</sub><sup>−</sup> as a major determinant. After seven days, root traits were analyzed, and a tissue localization assay was performed using Fluo-3 AM, DAF-FM, and salkowski reagents to visualize the distribution of Ca<sup>2+</sup>, NO, and indole-3-acetic acid (IAA) in root tissues, respectively. The study reveals that the cross-talk of nitric oxide (NO), auxin and calcium (Ca<sup>2+</sup>) modulates NO<sub>3</sub><sup>−</sup> regulated root growth in wheat seedlings. The changes in cytosolic Ca<sup>2+</sup> concentration ([Ca<sup>2+</sup>]<sub>cyt</sub>) are a major mediator in the regulation of root growth. High NO<sub>3</sub><sup>−</sup> (5 mM) in combination with exogenous IBA and Ca<sup>2+</sup> suppresses the root growth, with ethylene acting downstream of [Ca<sup>2+</sup>]<sub>cyt</sub>. We observed a synergistic effect between NO and endogenous IAA (Indole-3-acetic acid) in lateral root (LR) growth. In LRs, the external NO<sub>3</sub><sup>−</sup> enhances the NO production, which is further augmented by the elevated [Ca<sup>2+</sup>]<sub>cyt</sub> levels. Our results indicate that endogenous IAA plays a pivotal role in regulating root hair development on LR with NO and [Ca<sup>2+</sup>]<sub>cyt</sub> functioning downstream of the signalling cascade. However, the high NO<sub>3</sub><sup>−</sup> was found to counteract the root hair formation by importing the shoot-derived auxin. These findings provide valuable insights into the intricate signalling interactions between nitric oxide, auxin, and calcium in NO<sub>3</sub><sup>−</sup> regulated root development in wheat, with potential targets for enhancing nutrient uptake efficiency. Further work is necessary to identify downstream signalling components and examine how shoot-to-root signalling modulates the root architectures under different NO<sub>3</sub><sup>−</sup> regimes.</div></div>","PeriodicalId":19357,"journal":{"name":"Nitric oxide : biology and chemistry","volume":"159 ","pages":"Pages 11-22"},"PeriodicalIF":3.2,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144920295","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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