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1.
Methods Mol Biol ; 2384: 247-255, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-34550579

RESUMO

Primary monkey brain capillary endothelial cell cultures, with rat pericytes and astrocytes, provide an assay system for predicting the ability of oxytocin (OT) to cross the blood-brain barrier (BBB), using a commercially available in vitro BBB kit. The integrity of the in vitro "BBB," which has a high transendothelial electrical resistance (TEER), can be established approximately 4 days after preparations for experiments. Dominant endothelial transport of OT is from the upper (luminal blood side) to lower (abluminal brain side) chambers, dose-dependently. OT is transported by the receptor for advanced glycation end-products (RAGE) in endothelial cells, which is evidenced using the RAGE knockdown system with short hairpin RNA (shRNA) treatment. This in vitro assay system is useful for further assessment of OT transport across the BBB.

2.
Biol Open ; 2021 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-34812852

RESUMO

The full-length receptor for advanced glycation end products (RAGE) is a multiligand pattern recognition receptor. High-mobility group box 1 (HMGB1) is a RAGE ligand of damage-associated molecular patterns that elicits inflammatory reactions. The shedded isoform of RAGE and endogenous secretory RAGE (esRAGE), a splice variant, are soluble isoforms (sRAGE) that act as organ-protective decoys. However, the pathophysiologic roles of RAGE/sRAGE in acute kidney injury (AKI) remain unclear. We found that AKI was more severe, with enhanced renal tubular damage, macrophage infiltration, and fibrosis, in mice lacking both RAGE and sRAGE than in wild-type control mice. Using murine tubular epithelial cells (TECs), we demonstrated that hypoxia upregulated messenger RNA (mRNA) expression of HMGB1 and tumor necrosis factor α (TNF-α), whereas RAGE and esRAGE expressions were paradoxically decreased. Moreover, the addition of recombinant sRAGE canceled hypoxia-induced inflammation and promoted cell viability in cultured TECs. sRAGE administration prevented renal tubular damage in models of ischemia/reperfusion-induced AKI and of anti-glomerular basement membrane (anti-GBM) glomerulonephritis. These results suggest that sRAGE is a novel therapeutic option for AKI.

3.
Int J Mol Sci ; 22(21)2021 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-34769147

RESUMO

Pancreatic stellate cells (PSCs) mainly consist of cancer-associating fibroblasts in pancreatic ductal adenocarcinoma (PDAC). The receptor for advanced glycation end products (RAGE) is implicated in the pathophysiology of diabetic complications. Here, we studied the implication of RAGE in PSC activation in PDAC. The activation of cultured mouse PSCs was evaluated by qPCR. The induction of epithelial mesenchymal transition (EMT) in PDAC cell lines was assessed under stimulation with culture supernatant from activated PSCs. A total of 155 surgically resected PDAC subjects (83 nondiabetic, 18 with ≦3-years and 54 with >3-years history of diabetes) were clinicopathologically evaluated. A high-fat diet increased the expression of activated markers in cultured PSCs, which was abrogated by RAGE deletion. Culture supernatant from activated PSCs facilitated EMT of PDAC cells with elevation of TGF-ß and IL-6, but not from RAGE-deleted PSCs. Diabetic subjects complicated with metabolic syndrome, divided by cluster analysis, showed higher PSC activation and RAGE expression. In such groups, PDAC cells exhibited an EMT nature. The complication of metabolic syndrome with diabetes significantly worsened disease-free survival of PDAC subjects. Thus, RAGE in PSCs can be viewed as a new promoter and a future therapeutic target of PDAC in diabetic subjects with metabolic syndrome.

4.
Peptides ; 146: 170649, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34543678

RESUMO

The receptor for advanced glycation end-products (RAGE) binds oxytocin (OT) and transports it from the blood to the brain. As RAGE's OT-binding capacity was lost in RAGE knockout (KO) mice, we predicted that circulating concentrations of unbound (free) OT should be elevated compared to wild-type (WT) mice. However, this hypothesis has not yet been investigated. Unfortunately, the evaluation of the dynamics of circulating free and bound plasma OT is unclear in immunoassays, in part because of interference from plasma proteins. A radioimmunoassay (RIA) is considered the gold standard method for overcoming this issue, but is more challenging to implement; thus, commercially available enzyme-linked immunosorbent assays (ELISAs) are more commonly used. Here, we developed a pre-treatment method to remove the interference-causing components from plasma before performing ELISA. The acetonitrile protein precipitation (PPT) approach was reliable, with fewer steps needed to measure free OT concentrations than by solid-phase extraction of plasma samples. PPT-extracted plasma samples yielded higher concentrations of OT in RAGE KO mice than in WT mice using ELISA. After peripheral OT injection, free OT plasma levels spiked immediately then rapidly declined in WT mice, but remained high in KO mice. These results suggest that plasma samples with PPT pre-treatment appear to be superior and that circulating soluble RAGE can most likely serve as a buffer for plasma OT, which indicates a novel physiological function of RAGE.

7.
Artigo em Inglês | MEDLINE | ID: mdl-34398301

RESUMO

Chronic inflammation contributes to tumor development by creating a local microenvironment that facilitates neoplastic transformation and potentiates the progression of cancer. Esophageal cancer (EC) is an inflammation-associated malignancy with a poor prognosis. The nature of the switch between chronic inflammation of the esophagus and EC-related immunological changes remains unclear. Here, we examined the dynamic alterations of immune cells at different stages of chronic esophagitis, Barrett's esophagus (BE) and EC using an esophageal spontaneous carcinogenesis rat model. We also investigated the anticancer effects of metformin. To stimulate EC carcinogenesis, chronic gastroduodenal reflux esophagitis via esophagojejunostomy was induced in 120 rats in metformin-treated and non-treated (control) groups. After 40 weeks, BE and EC developed in 96.7% and 63.3% of the control group, and in 66.7% and 23.3% of the metformin-treated group, respectively. Flow cytometric analysis demonstrated that the balance of M1/M2-polarized or phospho-Stat3-positive macrophages, regulatory T, cytotoxic T, natural killer (NK), NK T cells, and Th17 T cells was dynamically changed at each stage of the disease and were resolved by metformin treatment. These findings clarify the immunity in esophageal carcinogenesis and suggest that metformin could suppress this disease by improving the immunosuppressive tumor microenvironment and immune evasion.

8.
Biomater Sci ; 9(18): 6142-6152, 2021 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-34346413

RESUMO

Heme binds to a parallel-stranded G-quadruplex DNA to form a peroxidase-mimicking heme-DNAzyme. An interpolyelectrolyte complex between the heme-DNAzyme and a cationic copolymer possessing protonated amino groups was characterized and the peroxidase activity of the complex was evaluated to elucidate the effect of the polymer on the catalytic activity of the heme-DNAzyme. We found that the catalytic activity of the heme-DNAzyme is enhanced through the formation of the interpolyelectrolyte complex due to the general acid catalysis of protonated amino groups of the polymer, enhancing the formation of the iron(IV)oxo porphyrin π-cation radical intermediate known as Compound I. This finding indicates that the polymer with protonated amino groups can act as a cocatalyst for the heme-DNAzyme in the oxidation catalysis. We also found that the enhancement of the activity of the heme-DNAzyme by the polymer depends on the local heme environment such as the negative charge density in the proximity of the heme and substrate accessibility to the heme. These findings provide novel insights as to molecular design of the heme-DNAzyme for enhancing its catalytic activity.


Assuntos
DNA Catalítico , Cátions , Heme , Peroxidase , Peroxidases , Polímeros
9.
Inorg Chem ; 60(15): 11206-11213, 2021 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-34289695

RESUMO

The catalytic cycle of a peroxidase-mimicking heme-DNAzyme involves an iron(IV)oxo porphyrin π-cation radical intermediate known as compound I formed through heterolytic O-O bond cleavage of an Fe3+-bound hydroperoxo ligand (Fe-OOH) in compound 0, like that of a heme enzyme such as horseradish peroxidase (HRP). Peroxidase assaying of complexes composed of chemically modified hemes possessing various electron densities of the heme iron atom (ρFe) and parallel-stranded tetrameric G-quadruplex DNAs of oligonucleotides d(TTAGGG), d(TTAGGGT), and d(TTAGGGA) was performed to elucidate the effects of the heme electronic structure and local heme environment on the catalytic activity of the heme-DNAzyme. The study revealed that the DNAzyme activity is enhanced through an increase in the ρFe and general base catalysis of the adenine base adjacent to the heme, which are reminiscent of the "push" and "pull" mechanisms in the catalytic cycle of HRP, respectively, and that the activity of the heme-DNAzyme can be independently controlled through the heme electronic structure and local heme environment. These findings allow a deeper understanding of the structure-function relationship of the peroxidase-mimicking heme-DNAzyme.


Assuntos
Materiais Biomiméticos/química , Materiais Biomiméticos/metabolismo , DNA Catalítico/química , DNA Catalítico/metabolismo , Heme/química , Heme/metabolismo , Peroxidase/metabolismo , Biocatálise , Elétrons
10.
PLoS Pathog ; 17(6): e1009649, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-34081755

RESUMO

Parasitic helminths can reside in humans owing to their ability to disrupt host protective immunity. Receptor for advanced glycation end products (RAGE), which is highly expressed in host skin, mediates inflammatory responses by regulating the expression of pro-inflammatory cytokines and endothelial adhesion molecules. In this study, we evaluated the effects of venestatin, an EF-hand Ca2+-binding protein secreted by the parasitic helminth Strongyloides venezuelensis, on RAGE activity and immune responses. Our results demonstrated that venestatin bound to RAGE and downregulated the host immune response. Recombinant venestatin predominantly bound to the RAGE C1 domain in a Ca2+-dependent manner. Recombinant venestatin effectively alleviated RAGE-mediated inflammation, including footpad edema in mice, and pneumonia induced by an exogenous RAGE ligand. Infection experiments using S. venezuelensis larvae and venestatin silencing via RNA interference revealed that endogenous venestatin promoted larval migration from the skin to the lungs in a RAGE-dependent manner. Moreover, endogenous venestatin suppressed macrophage and neutrophil accumulation around larvae. Although the invasion of larvae upregulated the abundance of RAGE ligands in host skin tissues, mRNA expression levels of tumor necrosis factor-α, cyclooxygenase-2, endothelial adhesion molecules vascular cell adhesion protein-1, intracellular adhesion molecule-1, and E-selectin were suppressed by endogenous venestatin. Taken together, our results indicate that venestatin suppressed RAGE-mediated immune responses in host skin induced by helminthic infection, thereby promoting larval migration. The anti-inflammatory mechanism of venestatin may be targeted for the development of anthelminthics and immunosuppressive agents for the treatment of RAGE-mediated inflammatory diseases.


Assuntos
Proteínas de Helminto/metabolismo , Interações Hospedeiro-Parasita/fisiologia , Receptor para Produtos Finais de Glicação Avançada/metabolismo , Strongyloides/imunologia , Strongyloides/metabolismo , Estrongiloidíase/metabolismo , Animais , Larva/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Strongyloides/patogenicidade
11.
J Neurochem ; 158(2): 311-327, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33871064

RESUMO

Neuroinflammation is initiated by activation of the brain's innate immune system in response to an inflammatory challenge. Insufficient control of neuroinflammation leads to enhanced or prolonged pathology in various neurological conditions including multiple sclerosis and Alzheimer's disease. Nicotinamide adenine dinucleotide (NAD+ ) plays critical roles in cellular energy metabolism and calcium homeostasis. Our previous study demonstrated that deletion of CD38, which consumes NAD+ , suppressed cuprizone-induced demyelination, neuroinflammation, and glial activation. However, it is still unknown whether CD38 directly affects neuroinflammation through regulating brain NAD+ level. In this study, we investigated the effect of CD38 deletion and inhibition and supplementation of NAD+ on lipopolysaccharide (LPS)-induced neuroinflammation in mice. Intracerebroventricular injection of LPS significantly increased CD38 expression especially in the hippocampus. Deletion of CD38 decreased LPS-induced inflammatory responses and glial activation. Pre-administration of apigenin, a flavonoid with CD38 inhibitory activity, or nicotinamide riboside (NR), an NAD+ precursor, increased NAD+ level, and significantly suppressed induction of cytokines and chemokines, glial activation and subsequent neurodegeneration after LPS administration. In cell culture, LPS-induced inflammatory responses were suppressed by treatment of primary astrocytes or microglia with apigenin, NAD+ , NR or 78c, the latter a specific CD38 inhibitor. Finally, all these compounds suppressed NF-κB signaling pathway in microglia. These results suggest that CD38-mediated neuroinflammation is linked to NAD+ consumption and that boosting NAD+ by CD38 inhibition and NR supplementation directly suppress neuroinflammation in the brain.


Assuntos
ADP-Ribosil Ciclase 1/antagonistas & inibidores , Astrócitos/efeitos dos fármacos , Astrócitos/patologia , Inflamação/induzido quimicamente , Inflamação/patologia , Lipopolissacarídeos , Glicoproteínas de Membrana/antagonistas & inibidores , Microglia/efeitos dos fármacos , Microglia/patologia , NAD/metabolismo , Niacinamida/análogos & derivados , Compostos de Piridínio/farmacologia , Animais , Apigenina/farmacologia , Quimiocinas/metabolismo , Citocinas/metabolismo , Deleção de Genes , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Injeções Intraventriculares , Lipopolissacarídeos/administração & dosagem , Ativação de Macrófagos/efeitos dos fármacos , Masculino , Camundongos , Camundongos Endogâmicos ICR , Camundongos Knockout , NAD/farmacologia , NF-kappa B/genética , Degeneração Neural , Niacinamida/farmacologia
12.
Sci Rep ; 11(1): 8336, 2021 04 16.
Artigo em Inglês | MEDLINE | ID: mdl-33863932

RESUMO

Thoracic dorsal root ganglia (tDRG) contribute to fluid secretion in the upper airways. Inflammation potentiates DRG responses, but the mechanisms remain under investigation. The receptor for advanced glycation end-products (RAGE) underlies potentiation of DRG responses in pain pathologies; however, its role in other sensory modalities is less understood. We hypothesize that RAGE contributes to electrophysiological and biochemical changes in tDRGs during inflammation. We used tDRGs and tracheas from wild types (WT), RAGE knock-out (RAGE-KO), and with the RAGE antagonist FPS-ZM1, and exposed them to lipopolysaccharides (LPS). We studied: capsaicin (CAP)-evoked currents and action potentials (AP), tracheal submucosal gland secretion, RAGE expression and downstream pathways. In WT neurons, LPS increased CAP-evoked currents and AP generation, and it caused submucosal gland hypersecretion in tracheas from WT mice exposed to LPS. In contrast, LPS had no effect on tDRG excitability or gland secretion in RAGE-KO mice or mice treated with FPS-ZM1. LPS upregulated full-length RAGE (encoded by Tv1-RAGE) and downregulated a soluble (sRAGE) splice variant (encoded by MmusRAGEv4) in tDRG neurons. These data suggest that sensitization of tDRG neurons contributes to hypersecretion in the upper airways during inflammation. And at least two RAGE variants may be involved in these effects of LPS.


Assuntos
Gânglios Espinais/fisiopatologia , Lipopolissacarídeos/efeitos adversos , Receptor para Produtos Finais de Glicação Avançada/fisiologia , Mucosa Respiratória/metabolismo , Traqueia/metabolismo , Potenciais de Ação/efeitos dos fármacos , Animais , Benzamidas/farmacologia , Regulação para Baixo/efeitos dos fármacos , Expressão Gênica , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptor para Produtos Finais de Glicação Avançada/antagonistas & inibidores , Receptor para Produtos Finais de Glicação Avançada/genética , Receptor para Produtos Finais de Glicação Avançada/metabolismo , Regulação para Cima/efeitos dos fármacos
13.
Biochem Biophys Res Commun ; 555: 74-80, 2021 05 28.
Artigo em Inglês | MEDLINE | ID: mdl-33813279

RESUMO

The engagement of the receptor for advanced glycation end-products (receptor for AGEs, RAGE) with diverse ligands could elicit chronic vascular inflammation, such as atherosclerosis. Binding of cytoplasmic tail RAGE (ctRAGE) to diaphanous-related formin 1 (Diaph1) is known to yield RAGE intracellular signal transduction and subsequent cellular responses. However, the effectiveness of an inhibitor of the ctRAGE/Diaph1 interaction in attenuating the development of atherosclerosis is unclear. In this study, using macrophages from Ager+/+ and Ager-/- mice, we validated the effects of an inhibitor on AGEs-RAGE-induced foam cell formation. The inhibitor significantly suppressed AGEs-RAGE-evoked Rac1 activity, cell invasion, and uptake of oxidized low-density lipoprotein, as well as AGEs-induced NF-κB activation and upregulation of proinflammatory gene expression. Moreover, expression of Il-10, an anti-inflammatory gene, was restored by this antagonist. These findings suggest that the RAGE-Diaph1 inhibitor could be a potential therapeutic drug against RAGE-related diseases, such as chronic inflammation and atherosclerosis.


Assuntos
Células Espumosas/metabolismo , Macrófagos Peritoneais/patologia , Receptor para Produtos Finais de Glicação Avançada/antagonistas & inibidores , Receptor para Produtos Finais de Glicação Avançada/metabolismo , Animais , Antígenos de Neoplasias/genética , Antígenos de Neoplasias/metabolismo , Expressão Gênica , Inflamação/genética , Inflamação/patologia , Lipoproteínas LDL/metabolismo , Macrófagos Peritoneais/metabolismo , Masculino , Camundongos Endogâmicos C57BL , Camundongos Mutantes , Proteínas Quinases Ativadas por Mitógeno/genética , Proteínas Quinases Ativadas por Mitógeno/metabolismo , NF-kappa B/metabolismo , Neuropeptídeos/metabolismo , Fosforilação/efeitos dos fármacos , Ratos , Receptor para Produtos Finais de Glicação Avançada/genética , Transdução de Sinais/efeitos dos fármacos , Proteínas rac1 de Ligação ao GTP/metabolismo
14.
Physiol Behav ; 235: 113395, 2021 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-33757778

RESUMO

Receptor for advanced glycation end-products (RAGE) is a pattern recognition molecule belonging to the immunoglobulin superfamily, and it plays a role in the remodeling of endothelial cells under pathological conditions. Recently, it was shown that RAGE is a binding protein for oxytocin (OT) and a transporter of OT to the brain on neurovascular endothelial cells via blood circulation. Deletion of the mouse RAGE gene, Ager (RAGE KO), induces hyperactivity in male mice. Impairment of pup care by mother RAGE KO mice after stress exposure results in the death of neonates 1-2 days after pup birth. Therefore, to understand the role of RAGE during the postpartum period, this study aims to examine parental behavior in female RAGE KO mice and ultrasonic vocalizations in pups. RAGE KO mothers without stress before delivery raised their pups and displayed hyperactivity at postpartum day (PPD) 3. KO dams showed impaired retrieval or interaction behavior after additional stress, such as body restraint stress or exposure to a novel environment, but such impaired behavior disappeared at PPD 7. Postnatal day 3 pups emitted ultrasonic vocalizations at >60 kHz as a part of the mother-pup relationship, but the number and category of calls by RAGE KO pups were significantly lower than wild-type pups. The results indicate that RAGE is important in the manifestation of normal parental behavior in dams and for receiving maternal care by mouse pups; moreover, brain OT recruited by RAGE plays a role in damping of signals of additional external stress and endogenous stress during the early postpartum period. Thus, RAGE-dependent OT may be critical for initiating and maintaining the normal mother-child relationship.


Assuntos
Células Endoteliais , Mães , Animais , Feminino , Humanos , Masculino , Comportamento Materno , Camundongos , Período Pós-Parto , Receptor para Produtos Finais de Glicação Avançada/genética
15.
J Neuroendocrinol ; 33(3): e12963, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33733541

RESUMO

Oxytocin (OT) is a neuropeptide hormone. Single and repetitive administration of OT increases social interaction and maternal behaviour in humans and mammals. Recently, it was found that the receptor for advanced glycation end-products (RAGE) is an OT-binding protein and plays a critical role in the uptake of OT to the brain after peripheral OT administration. Here, we address some unanswered questions on RAGE-dependent OT transport. First, we found that, after intranasal OT administration, the OT concentration increased in the extracellular space of the medial prefrontal cortex (mPFC) of wild-type male mice, as measured by push-pull microperfusion. No increase of OT in the mPFC was observed in RAGE knockout male mice. Second, in a reconstituted in vitro blood-brain barrier system, inclusion of the soluble form of RAGE (endogenous secretory RAGE [esRAGE]), an alternative splicing variant, in the luminal (blood) side had no effect on the transport of OT to the abluminal (brain) chamber. Third, OT concentrations in the cerebrospinal fluid after i.p. OT injection were slightly higher in male mice overexpressing esRAGE (esRAGE transgenic) compared to those in wild-type male mice, although this did not reach statistical significance. Although more extensive confirmation is necessary because of the small number of experiments in the present study, the reported data support the hypothesis that RAGE may be involved in the transport of OT to the mPFC from the circulation. These results suggest that the soluble form of RAGE in the plasma does not function as a decoy in vitro.

16.
Sci Rep ; 11(1): 555, 2021 01 12.
Artigo em Inglês | MEDLINE | ID: mdl-33436955

RESUMO

It remains unclear how hepatic steatosis links to inflammation. Leukocyte cell-derived chemotaxin 2 (LECT2) is a hepatokine that senses fat in the liver and is upregulated prior to weight gain. The aim of this study was to investigate the significance of LECT2 in the development of nonalcoholic steatohepatitis (NASH). In human liver biopsy samples, elevated LECT2 mRNA levels were positively correlated with body mass index (BMI) and increased in patients who have steatosis and inflammation in the liver. LECT2 mRNA levels were also positively correlated with the mRNA levels of the inflammatory genes CCR2 and TLR4. In C57BL/6J mice fed with a high-fat diet, mRNA levels of the inflammatory cytokines Tnfa and Nos2 were significantly lower in Lect2 KO mice. In flow cytometry analyses, the number of M1-like macrophages and M1/M2 ratio were significantly lower in Lect2 KO mice than in WT mice. In KUP5, mouse kupffer cell line, LECT2 selectively enhanced the LPS-induced phosphorylation of JNK, but not that of ERK and p38. Consistently, LECT2 enhanced the LPS-induced phosphorylation of MKK4 and TAB2, upstream activators of JNK. Hepatic expression of LECT2 is upregulated in association with the inflammatory signature in human liver tissues. The elevation of LECT2 shifts liver residual macrophage to the M1-like phenotype, and contributes to the development of liver inflammation. These findings shed light on the hepatokine LECT2 as a potential therapeutic target that can dissociate liver steatosis from inflammation.


Assuntos
Peptídeos e Proteínas de Sinalização Intercelular/genética , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Ativação de Macrófagos/genética , Hepatopatia Gordurosa não Alcoólica/genética , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Animais , Linhagem Celular , Dieta Hiperlipídica/efeitos adversos , Expressão Gênica/genética , Inflamação/genética , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Macrófagos do Fígado/metabolismo , Fígado/citologia , Camundongos Endogâmicos C57BL , Terapia de Alvo Molecular , Hepatopatia Gordurosa não Alcoólica/etiologia , Hepatopatia Gordurosa não Alcoólica/terapia , Fosforilação/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Regulação para Cima
17.
J Inorg Biochem ; 216: 111336, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33453496

RESUMO

Heme has been receiving considerable interest as a prosthetic group of ribozymes and deoxyribozymes, because heme-bound nucleic acids exhibit peroxidase-like catalytic activities (Travascio, P., Li, Y., and Sen, D. (1998) Chem. Biol, 5, 505-517). The interaction of heme with dimeric G-quadruplexes formed from d(TAGGGTTAGGGT) and d(TAGGGTTAGGGA) has been characterized to gain a deeper understanding of the molecular recognition of G-quadruplex DNAs by heme. We found that heme binds selectively to the 3'-terminal G-quartet of a dimeric parallel G-quadruplex of d(TAGGGTTAGGGT), whereas binding of heme to a dimeric antiparallel G-quadruplex of d(TAGGGTTAGGGA) does not occur, suggesting that an orderly arrangement of the constituent guanine deoxyribose rings, with respect to the G-quartet plane, is crucial for the binding of heme to the DNA. The preferential binding of heme to the 3'-terminal G-quartet of parallel G-quadruplex DNAs allowed a systematic modification of the heme environment in the complex through the DNA sequence. The activity of the complexes was found to increase with increasing number of adenine bases adjacent to the heme in the complexes, possibly due to improvement of the accessibility of aromatic substrate, i.e., 10-acetyl-3,7-dihydroxyphenoxazine, to the heme, and an increase in the frequency of appearance of a specific orientation of the adenine bases, with respect to the heme, optimized for its activity as an acid-base catalyst to enhance the peroxidase activity of the complex.


Assuntos
Quadruplex G , Heme/química , Modelos Moleculares
18.
Glycoconj J ; 38(3): 303-310, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33108607

RESUMO

The receptor for advanced glycation end-products (receptor for AGEs, RAGE) is a pattern recognition receptor. The interaction of RAGE with its ligands, such as AGEs, S100 proteins, high mobility group box-1 (HMGB1), and lipopolysaccharides (LPS), is known to play a pivotal role in the propagation of immune responses and inflammatory reactions. The ligand-RAGE interaction elicits cellular responses, for example, in myeloid and lymphoid cells, through distinct pathways by activating NF-κB and Rac1/cdc42, which lead to cytokine production, cell migration, phagocytosis, maturation, and polarization. Recently, oxytocin, a peptide hormone and neuropeptide, was identified as a novel binding molecule for the RAGE; however, it cannot compete with the interaction of RAGE with other ligands or induce RAGE intracellular signaling. The RAGE transports oxytocin from the blood into the brain and regulates brain functions. In this review, we summarize the current understanding of glycation reaction, AGEs, and the RAGE-mediated biological responses as well as the physiological role of RAGE in immunity and social behaviors, particularly, maternal bonding.

19.
Physiol Behav ; 229: 113255, 2021 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-33221393

RESUMO

Diabetes in humans has been associated for a long time with cognitive dysfunction. In rodent animal models, cognitive dysfunction can manifest as impaired hippocampal synaptic plasticity. Particular attention has been concentrated on the receptor for advanced glycation end products (RAGE), which is implicated in multiple diabetic complications involving the development of vascular and peripheral nerve abnormalities. In this study, we hypothesize that RAGE signaling alters glutamate receptor function and expression, impairing synaptic transmission in the hippocampus. Using preparations of hippocampal slices from male mice, we show a RAGE-dependent decrease in long-term potentiation (LTP) and an increase in paired-pulse facilitation (PPF) following streptozotocin (STZ)-induced diabetes. Consistently, in hippocampal cultures from male and female neonatal mice, high glucose caused a RAGE-dependent reduction of AMPA- but not NMDA-evoked currents, and an increase in cytosolic reactive oxygen species (ROS). Consistently, when cultures were co-treated with high glucose and the RAGE antagonist FPS-ZM1, AMPA-evoked currents were unchanged. Hippocampi from STZ-induced hyperglycemic wild type (WT) mice showed increased RAGE expression concomitant with a decrease of both expression and phosphorylation (Ser 831 and 845) of the AMPA GluA1 subunit. We found these changes correlated to activation of the MAPK pathway, consistent with decreased pJNK/JNK ratio and the JNK kinase, pMEK7. As no changes in expression or phosphorylation of regulatory proteins were observed in hippocampi from STZ-induced hyperglycemic RAGE-KO mice, we report a RAGE-dependent impairment in the hippocampi of hyperglycemic WT mice, with reduced AMPA receptor expression/function and LTP deficits.


Assuntos
Hipocampo , Receptores de AMPA , Animais , Feminino , Hipocampo/metabolismo , Masculino , Camundongos , Camundongos Obesos , Receptor para Produtos Finais de Glicação Avançada/metabolismo , Receptores de AMPA/metabolismo , Transmissão Sináptica
20.
Inorg Chem ; 60(2): 1021-1027, 2021 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-33356193

RESUMO

Mössbauer spectroscopy has been used to characterize oxygenated myoglobins (oxy Mbs) reconstituted with native and chemically modified 57Fe-enriched heme cofactors with different electron densities of the heme Fe atom (ρFe) and to elucidate the effect of a change in the ρFe on the nature of the bond between heme Fe and oxygen (O2), i.e., the Fe-O2 bond, in the protein. Quadrupole splitting (ΔEQ) was found to decrease with decreasing ρFe, and the observed ρFe-dependent ΔEQ confirmed an increase in the contribution of the ferric-superoxide (Fe3+-O2-) form to the resonance hybrid of the Fe-O2 fragment with decreasing ρFe. These observations explicitly accounted for the lowering of O2 affinity of the protein due to an increase in the O2 dissociation rate and a decrease in the autoxidation reaction rate of oxy Mb through decreasing H+ affinity of the bound ligand with decreasing ρFe. Therefore, the present study demonstrated the mechanism underlying the electronic control of O2 affinity and the autoxidation of the protein through the heme electronic structure. Carbon monoxide (CO) adducts of reconstituted Mbs (CO-Mbs) were similarly characterized, and we found that the resonance between the two canonical forms of the Fe-CO fragment was also affected by a change in ρFe. Thus, the nature of the Fe-ligand bond in the protein was found to be affected by the ρFe.


Assuntos
Heme/química , Ferro/química , Mioglobina/química , Oxigênio/química , Monóxido de Carbono/química , Elétrons , Estrutura Molecular , Espectroscopia de Mossbauer
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