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1.
Front Endocrinol (Lausanne) ; 14: 1172060, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37547309

RESUMO

Organismal energy balance is controlled by inter-tissue communication mediated by the nervous system and hormones, the disruption of which causes metabolic syndrome exemplified by diabetes and obesity. Fat-storing adipose tissue, especially those located in subcutaneous white adipose tissue, secretes leptin in a proportion of fat mass, inhibiting the accumulation of organismal fat by suppressing appetite and promoting energy expenditure. With a prevalence of obesity that exhibits hyperleptinemia, most of the investigation on leptin has been focused on how it works and how it does not, which is expected to be a clue for treating obesity. In contrast, how it is synthesized, transported, and excreted, all of which are relevant to the homeostasis of blood leptin concentration, are not much understood. Of note, acute leptin reduction after hyperleptinemia in the context of obesity exhibited a beneficial effect on obesity and insulin sensitivity, indicating that manipulation of circulating leptin level may provide a therapeutic strategy. Technological advances such as "omics" analysis combined with sophisticated gene-engineered mice studies in the past decade enabled a deeper understanding of leptin's action in more detail. Here, we summarize the updated understanding of the action as well as regulation of leptin and point out the emerging direction of research on leptin.


Assuntos
Diabetes Mellitus , Leptina , Camundongos , Animais , Leptina/metabolismo , Adipocinas/metabolismo , Tecido Adiposo/metabolismo , Obesidade/metabolismo , Diabetes Mellitus/metabolismo
2.
Mol Pharmacol ; 103(5): 266-273, 2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-36868792

RESUMO

Alzheimer's disease (AD) is a neurodegenerative disease that is accompanied by memory decline and cognitive dysfunction. Aggregated amyloid ß formation and accumulation may be one of the underlying mechanisms of the pathophysiology of AD. Therefore, compounds that can inhibit amyloid ß aggregation may be useful for treatment. Based on this hypothesis, we screened plant compounds used in Kampo medicine for chemical chaperone activity and identified that alkannin had this property. Further analysis indicated that alkannin could inhibit amyloid ß aggregation. Importantly, we also found that alkannin inhibited amyloid ß aggregation after aggregates had already formed. Through the analysis of circular dichroism spectra, alkannin was found to inhibit ß-sheet structure formation, which is an aggregation-prone toxic structure. Furthermore, alkannin attenuated amyloid ß-induced neuronal cell death in PC12 cells, ameliorated amyloid ß aggregation in the AD model of Caenorhabditis elegans (C. elegans), and inhibited chemotaxis observed in AD C. elegans, suggesting that alkannin could potentially inhibit neurodegeneration in vivo. Overall, these results suggest that alkannin may have novel pharmacological properties for inhibiting amyloid ß aggregation and neuronal cell death in AD. SIGNIFICANCE STATEMENT: Aggregated amyloid ß formation and accumulation is one of the underlying mechanisms of the pathophysiology of Alzheimer's disease. We found that alkannin had chemical chaperone activity, which can inhibit ß-sheet structure formation of amyloid ß and its aggregation, neuronal cell death, and Alzheimer's disease phenotype in C. elegans. Overall, alkannin may have novel pharmacological properties for inhibiting amyloid ß aggregation and neuronal cell death in Alzheimer's disease.


Assuntos
Doença de Alzheimer , Doenças Neurodegenerativas , Animais , Ratos , Doença de Alzheimer/tratamento farmacológico , Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/química , Peptídeos beta-Amiloides/genética , Peptídeos beta-Amiloides/metabolismo , Caenorhabditis elegans/metabolismo , Amiloide/uso terapêutico
3.
PLoS One ; 17(12): e0278965, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36512575

RESUMO

Abnormally high serum homocysteine levels have been associated with several disorders, including obesity, cardiovascular diseases or neurological diseases. Leptin is an anti-obesity protein and its action is mainly mediated by the activation of its Ob-R receptor in neuronal cells. The inability of leptin to induce activation of its specific signaling pathways, especially under endoplasmic reticulum stress, leads to the leptin resistance observed in obesity. The present study examined the effect of homocysteine on leptin signaling in SH-SY5Y neuroblastoma cells expressing the leptin receptor Ob-Rb. Phosphorylation of the signal transducer and activator of transcription (STAT3) and leptin-induced STAT3 transcriptional activity were significantly inhibited by homocysteine treatment. These effects may be specific to homocysteine and to the leptin pathway, as other homocysteine-related compounds, namely methionine and cysteine, have weak effect on leptin-induced inhibition of STAT3 phosphorylation, and homocysteine has no impact on IL-6-induced activation of STAT3. The direct effect of homocysteine on leptin-induced Ob-R activation, analyzed by Ob-R BRET biosensor to monitor Ob-R oligomerization and conformational change, suggested that homocysteine treatment does not affect early events of leptin-induced Ob-R activation. Instead, we found that, unlike methionine or cysteine, homocysteine increases the expression of the endoplasmic reticulum (ER) stress response gene, a homocysteine-sensitive ER resident protein. These results suggest that homocysteine may induce neuronal resistance to leptin by suppressing STAT3 phosphorylation downstream of the leptin receptor via ER stress.


Assuntos
Leptina , Neuroblastoma , Humanos , Leptina/metabolismo , Receptores para Leptina/genética , Homocisteína/farmacologia , Cisteína/farmacologia , Estresse do Retículo Endoplasmático , Fator de Transcrição STAT3/metabolismo , Obesidade/metabolismo , Metionina/farmacologia
4.
Am J Physiol Cell Physiol ; 323(6): C1633-C1641, 2022 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-36189972

RESUMO

Alzheimer's disease is an intractable disease, and the accumulation of amyloid ß in the brain is thought to be involved in the onset of the disease. Additionally, abnormal protein accumulation due to autophagic deficiency may also be involved in disease progression. Autophagy involves a mechanism called selective autophagy. However, the relationship between selective autophagy and the amyloid precursor protein (APP) remains unclear. In the present study, we analyzed the interaction between p62, an adapter protein, and an APP-related molecule and found that p62 interacted with the COOH-terminal fragment of APP (C60). When C60 and p62 are overexpressed, aggregates are formed and C60 is degraded by autophagy. These aggregates cannot be easily degraded, even with a reducing agent. We also found that autophagosome- and lysosome marker-positive vesicles were formed in the C60- and p62-expressing cells. Superresolution technology also revealed that p62-C60-positive autophagosomes were formed in the cells. Overall, these results suggest that p62 may bind with C60 to form aggregates and induce autophagy in autophagosomes. These results reveal one of the mechanisms underlying the progression of Alzheimer's disease, in which selective autophagy may be involved.


Assuntos
Doença de Alzheimer , Precursor de Proteína beta-Amiloide , Humanos , Precursor de Proteína beta-Amiloide/genética , Precursor de Proteína beta-Amiloide/metabolismo , Doença de Alzheimer/genética , Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides , Autofagia , Autofagossomos/metabolismo , Proteína Sequestossoma-1/genética , Proteína Sequestossoma-1/metabolismo
5.
Front Physiol ; 13: 854538, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35574480

RESUMO

Neuroimmune interactions between the immune system and CNS as well as peripheral organs such as the liver play a key role in the pathophysiological state of diseases. Unfolded protein responses (UPRs), which are activated by cells in response to endoplasmic reticulum stress, have been linked to the occurrence of inflammation diseases, neurodegenerative diseases, and metabolic disorders such as type 2 diabetes. Peripheral injection of lipopolysaccharide (LPS) is known to induce a systemic inflammatory response, along with fever, anorexia, and depressive behaviors. LPS also elicits UPRs, although the underlying physiological mechanism remains unclear. In the present study, we investigated whether peripheral activation of the immune system can elicit UPRs in the CNS and liver. Peripheral injection of LPS is known to elevate pro-inflammatory cytokines in the liver, hypothalamus and hippocampus. We report that LPS-induced systemic inflammation elicits UPRs in the liver, but not the hypothalamus. Injection of LPS upregulated the expression levels of glucose-regulated protein 78 and pro-apoptotic transcription factor C/EBP homologous protein, along with increased splicing of X-box binding protein one mRNA in the liver, but not in the hypothalamus and hippocampus. Myeloid differentiation primary response 88 (MyD88), an adaptor protein, is known to play a key role in the signal transduction of LPS mediated by Toll-like receptor 4. Using MyD88 deficient mice, we found that LPS-induced UPRs occurred independently of MyD88 expression. In summary, peripheral activation of the immune system elicits UPRs in the liver, but not the hypothalamus and hippocampus, which may have implications for the pathophysiology of diseases.

6.
Cell Rep ; 38(12): 110541, 2022 03 22.
Artigo em Inglês | MEDLINE | ID: mdl-35320725

RESUMO

The histone chaperone complex FACT comprises SPT16 and SSRP1 and contributes to DNA replication, transcription, and repair, but how it plays such various roles is unclear. Here, we show that human SPT16 is ubiquitylated at lysine-674 (K674) by the DCAF14-CRL4 ubiquitin ligase. K674 is located in the middle domain of SPT16, and the corresponding residue of the yeast ortholog is critical for binding to histone H3.1-H4. We show that the middle domain of human SPT16 binds to histone H3.1-H4 and that this binding is inhibited by K674 ubiquitylation. Cells with heterozygous knockin of a K674R mutant of SPT16 manifest reduction of both SPT16 ubiquitylation and H3.1 in chromatin, a reduced population in mid S phase, impaired proliferation, and increased susceptibility to S phase stress. Our data thus indicate that SPT16 ubiquitylation by DCAF14-CRL4 regulates FACT binding to histones and may thereby control DNA replication-coupled histone incorporation into chromatin.


Assuntos
Histonas , Proteínas de Saccharomyces cerevisiae , Cromatina , Proteínas de Ligação a DNA , Proteínas de Grupo de Alta Mobilidade , Chaperonas de Histonas , Humanos , Lisina , Receptores de Interleucina-17 , Saccharomyces cerevisiae , Fatores de Elongação da Transcrição , Ubiquitina-Proteína Ligases , Ubiquitinação
7.
J Pharmacol Exp Ther ; 381(2): 68-78, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35241633

RESUMO

Parkinson's disease (PD) is the second most common neurodegenerative disease. Although many monogenic variants have been identified that cause familial PD, most cases are sporadic and the mechanisms of sporadic PD onset remain unclear. We previously identified midnolin (MIDN) as a novel genetic risk factor for PD in a Japanese population. MIDN copy number loss was strongly associated with sporadic PD, which was replicated in a British population. Furthermore, suppression of MIDN expression in rat pheochromocytoma cells inhibits neurite outgrowth and expression of Parkin ubiquitin ligase. However, the detailed molecular mechanisms of MIDN expression are unknown. We, therefore, investigated the molecular mechanism of MIDN expression in human neuroblastoma SH-SY5Y cells. We found that MIDN expression was promoted by insulin via extracellular-signal regulated kinase1/2 and phosphoinositide 3-kinase-dependent pathways. In addition, MIDN promoter activity was enhanced by mutations at transcription factor AP-2 consensus sequences and reduced by mutations at cAMP response element-binding protein and activator protein 1 (AP-1) consensus sequences. The dominant-negative cAMP response element-binding protein mutant did not block MIDN promoter activity, but both the pharmacological inhibitor and decoy oligodeoxynucleotide for AP-1 significantly blocked its activity. Additionally, DNA binding of c-FOS and c-JUN to the AP-1 consensus sequence in the MIDN promoter was enhanced by insulin as determined by chromatin immunoprecipitation, which suggested that AP-1 positively regulated MIDN expression. Taken together, this study reveals molecular mechanisms of MIDN gene expression induced by insulin in neuronal cells, and drugs which promote MIDN expression may have potential to be a novel medicine for PD. SIGNIFICANCE STATEMENT: We demonstrated that insulin promotes midnolin expression via extracellular-signal regulated kinase 1/2 and phosphoinositide 3-kinase pathways. Furthermore, we identified the important region of the MIDN promoter and showed that transcription factors, including activator protein 1, positively regulate MIDN expression, whereas transcription factor AP-2 negatively regulates basal and insulin-induced MIDN expression. We believe that our observations are important and that they contribute to the development of novel drugs to treat Parkinson's disease.


Assuntos
Doenças Neurodegenerativas , Doença de Parkinson , Animais , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Expressão Gênica , Humanos , Insulina/farmacologia , Proteínas Nucleares , Doença de Parkinson/genética , Doença de Parkinson/metabolismo , Fosfatidilinositol 3-Quinase/genética , Fosfatidilinositol 3-Quinase/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Ratos , Fatores de Risco , Fator de Transcrição AP-1/genética , Fator de Transcrição AP-1/metabolismo , Fator de Transcrição AP-2/genética , Fator de Transcrição AP-2/metabolismo , Transcrição Gênica
8.
Front Genet ; 13: 1022339, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36685966

RESUMO

Genomic analysis has revealed that the genes for various chromatin regulators are mutated in many individuals with neurodevelopmental disorders (NDDs), emphasizing the important role of chromatin regulation in nervous system development and function. Chromatin regulation is mediated by writers, readers, and erasers of histone and DNA modifications, with such proteins being defined by specific domains. One of these domains is the SET domain, which is present in enzymes that catalyze histone methylation. Heterozygous loss-of-function mutations of the SETD5 (SET domain containing 5) gene have been identified in individuals with an NDD designated IDD23 (intellectual developmental disorder, autosomal dominant 23). KBG syndrome (named after the initials of the last names of the first three families identified with the condition) is characterized by features that either overlap with or are distinct from those of IDD23 and was initially thought to be caused only by mutations in the ANKRD11 (ankyrin repeat domain containing 11) gene. However, recent studies have identified SETD5 mutations in some KBG syndrome patients without ANKRD11 mutations. Here we summarize the neurobehavioral characterization of Setd5 +/- mice performed by four independent research groups, compare IDD23 and KBG phenotypes, and address the utility and future development of mouse models for elucidation of the mechanisms underlying NDD pathogenesis, with a focus on SETD5 and its related proteins.

9.
Mol Pharmacol ; 100(3): 181-192, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34127539

RESUMO

Conophylline (CNP) is a vinca alkaloid extracted from the Tabernaemontana divaricata plant. It has been reported that CNP induces autophagy in a mammalian target of rapamycin-independent manner, and thereby inhibits protein aggregation. However, the mode of action of CNP in inducing autophagy remains unknown. In this study, we identified glutathione peroxidase 4 (GPX4) as a CNP-binding protein by using thermal proteome profiling. The technique exploits changes in the thermal stability of proteins resulting from ligand interaction, which is capable of identifying compound-binding proteins without chemical modification. GPX4, an antioxidant protein that uses reduced glutathione as a cofactor, directly catalyzes the reduction of hydrogen peroxide, organic hydroperoxides, and lipid peroxides. GPX4 suppresses lipid peroxide accumulation, and thus plays a key role in protecting cells from oxidative damage. We found that treatment with CNP caused accumulation of lipid reactive oxygen species (ROS) in cultured cells. Furthermore, similarly with CNP treatment, GPX4 deficiency caused accumulation of lipid ROS and induced autophagy. These findings indicate that GPX4 is a direct target of CNP involved in autophagy induction. SIGNIFICANCE STATEMENT: The present study identified glutathione peroxidase 4 (GPX4) as a binding protein of conophylline (CNP) by using thermal proteome profiling (TPP). This study showed that CNP treatment, similarly with the inhibition of GPX4, induced lipid reactive oxygen species accumulation and autophagy. The present findings suggest that GPX4 is the CNP target protein involved in autophagy induction. Furthermore, these results indicate that TPP is a useful technique for determining the mechanism of natural compounds.


Assuntos
Fosfolipídeo Hidroperóxido Glutationa Peroxidase/metabolismo , Proteômica/métodos , Alcaloides de Vinca/farmacologia , Autofagia/efeitos dos fármacos , Autofagia/fisiologia , Linhagem Celular , Temperatura Alta , Humanos , Fosfolipídeo Hidroperóxido Glutationa Peroxidase/antagonistas & inibidores , Fosfolipídeo Hidroperóxido Glutationa Peroxidase/genética , Espécies Reativas de Oxigênio/metabolismo , Serina-Treonina Quinases TOR/metabolismo
10.
Neuroreport ; 32(12): 983-987, 2021 08 11.
Artigo em Inglês | MEDLINE | ID: mdl-34102647

RESUMO

Leptin plays an important role in energy intake and body weight homeostasis. Leptin is secreted mainly from white adipose tissue and circulates in the bloodstream, inhibiting food intake by activating the leptin receptor expressed on hypothalamic neurons. Recent studies have demonstrated leptin resistance as the main factor involved in the development of obesity. We and others have reported that leptin resistance is caused by endoplasmic reticulum (ER) stress due to the accumulation of unfolded protein in the ER. In the present study, we investigated whether isoflavones could affect ER stress and the subsequent development of leptin resistance. We showed that biochanin A, a family of isoflavones, strongly attenuated cell death induced by ER stress in neuronal cells, improved ER stress-induced impairments in leptin signaling, and suppressed ER stress-induced expression of glucose-regulated protein 78. These results suggest that biochanin A may have pharmacological properties that can ameliorate leptin resistance by reducing ER stress.


Assuntos
Estresse do Retículo Endoplasmático/efeitos dos fármacos , Genisteína/farmacologia , Leptina/antagonistas & inibidores , Leptina/metabolismo , Fitoestrógenos/farmacologia , Linhagem Celular Tumoral , Relação Dose-Resposta a Droga , Estresse do Retículo Endoplasmático/fisiologia , Humanos , Isoflavonas/farmacologia
11.
Antioxidants (Basel) ; 10(5)2021 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-33946318

RESUMO

Mitochondria are critical for hypothalamic function and regulators of metabolism. Hypothalamic mitochondrial dysfunction with decreased mitochondrial chaperone expression is present in type 2 diabetes (T2D). Recently, we demonstrated that a dysregulated mitochondrial stress response (MSR) with reduced chaperone expression in the hypothalamus is an early event in obesity development due to insufficient insulin signaling. Although insulin activates this response and improves metabolism, the metabolic impact of one of its members, the mitochondrial chaperone heat shock protein 10 (Hsp10), is unknown. Thus, we hypothesized that a reduction of Hsp10 in hypothalamic neurons will impair mitochondrial function and impact brain insulin action. Therefore, we investigated the role of chaperone Hsp10 by introducing a lentiviral-mediated Hsp10 knockdown (KD) in the hypothalamic cell line CLU-183 and in the arcuate nucleus (ARC) of C57BL/6N male mice. We analyzed mitochondrial function and insulin signaling utilizing qPCR, Western blot, XF96 Analyzer, immunohistochemistry, and microscopy techniques. We show that Hsp10 expression is reduced in T2D mice brains and regulated by leptin in vitro. Hsp10 KD in hypothalamic cells induced mitochondrial dysfunction with altered fatty acid metabolism and increased mitochondria-specific oxidative stress resulting in neuronal insulin resistance. Consequently, the reduction of Hsp10 in the ARC of C57BL/6N mice caused hypothalamic insulin resistance with acute liver insulin resistance.

12.
Front Neurosci ; 15: 621446, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33790733

RESUMO

Myeloid differentiation primary response 88 (MyD88) is an adapter protein of the toll-like receptor (TLR) family that regulates innate immune function. Here, we identified a novel role of MyD88 in regulating stress response. MyD88 deficiency decreased immobility time in the forced swim test without affecting locomotor activity in mice. Immobilization stress-induced production of serum corticosterone was also completely inhibited by MyD88 deficiency. Stress induced decrease in glucocorticoid receptor in the hippocampus. On the other hand, stress exposure in MyD88 deficient mice did not cause decrease in its level in the hippocampus. Furthermore, immobilization stress-induced reduction of brain-derived neurotrophic factor (BDNF) levels in the hippocampus was ameliorated by MyD88 deficiency. These results suggest that MyD88 deficiency attenuates depression-like behavior by regulating corticosterone and BDNF levels. Overall, these results indicate the key role of MyD88 in regulating stress response in mice.

13.
Cytotechnology ; : 769-783, 2019 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-31147813

RESUMO

This study aimed to shed light on the protective and therapeutic anti-osteoporotic effects and mechanisms of action of grapefruit juice (GFJ) on prednisolone-induced osteoporosis a rat femoral fracture model. We found that treating rats with GFJ before and/or after prednisolone-induced osteoporosis resulted in increased bone density, total mineral content, and calcium content to counteract the osteoporotic effects of prednisolone. In parallel, the histological and ultrastructural results of the GFJ-treated groups correlated well with enhanced breaking strength of femurs subjected to a constant load. Furthermore, GFJ treatment before and after prednisolone-induced osteoporosis decreased plasma alkaline phosphatase and tartrate-resistant acid phosphatase activities and increased the level of insulin-like growth factor 1. Mechanistically, our immunohistochemistry study showed that GFJ ameliorated prednisolone-induced osteocalcin depletion, decreased receptor activator of nuclear factor kappa-B ligand (RANKL) expression, and increased osteoprotegerin (OPG) expression. GFJ showed a beneficial anti-osteoporotic effect against prednisolone-induced osteoporosis in rats, possibly via the RANKL/OPG axis, suggesting that GFJ might be a good candidate for developing anti-osteoporotic drugs.

14.
Pharmacol Rep ; 71(2): 289-298, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30826569

RESUMO

BACKGROUND: Nor-wogonin, a polyhydroxy flavone, has been shown to possess antitumor activity. However, the mechanisms responsible for its antitumor activity are poorly studied. Herein, we investigated the mechanisms of nor-wogonin actions in triple-negative breast cancer (TNBC) cells. METHODS: Effects of nor-wogonin on cell proliferation and viability of four TNBC cell lines (MDA-MB-231, BT-549, HCC70, and HCC1806) and two non-tumorigenic breast cell lines (MCF-10A and AG11132) were assessed by BrdU incorporation assays and trypan blue dye exclusion tests. Cell cycle and apoptosis analyses were carried out by flow cytometry. Protein expression was analyzed by immunoblotting. RESULTS: Nor-wogonin significantly inhibited the growth and decreased the viability of TNBC cells; however, it exhibited no or minimal effects in non-tumorigenic breast cells. Nor-wogonin (40 µM) was a more potent anti-proliferative and cytotoxic agent than wogonin (100 µM) and wogonoside (100 µM), which are structurally related to nor-wogonin. The antitumor effects of nor-wogonin can be attributed to cell cycle arrest via reduction of the expression of cyclin D1, cyclin B1, and CDK1. Furthermore, nor-wogonin induced mitochondrial apoptosis, (as evidenced by the increase in % of cells that are apoptotic), decreases in the mitochondrial membrane potential (ΔΨm), increases in Bax/Bcl-2 ratio, and caspase-3 cleavage. Moreover, nor-wogonin attenuated the expression of the nuclear factor kappa-B and activation of signal transducer and activator of transcription 3 pathways, which can be correlated with suppression of transforming growth factor-ß-activated kinase 1 in TNBC cells. CONCLUSION: These results showed that nor-wogonin might be a potential multi-target agent for TNBC treatment.


Assuntos
Antineoplásicos Fitogênicos/farmacologia , Apoptose/efeitos dos fármacos , Flavonas/farmacologia , Neoplasias de Mama Triplo Negativas/tratamento farmacológico , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Regulação para Baixo/genética , Feminino , Flavanonas/farmacologia , Glucosídeos/farmacologia , Humanos , MAP Quinase Quinase Quinases/genética , NF-kappa B/genética , Fator de Transcrição STAT3/genética , Neoplasias de Mama Triplo Negativas/genética
15.
Am J Physiol Cell Physiol ; 316(5): C641-C648, 2019 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-30789753

RESUMO

Insensitivity to the antiobesity hormone, leptin, has been suggested to be involved in the pathogenesis of obesity. However, the pathological mechanisms underlying the development of leptin resistance are not well-understood. This study aimed to examine the pathological mechanisms of leptin resistance in obesity. In the present study, we found that 4-hydroxy-2-nonenal (4-HNE), an aldehyde, may be involved in the development of leptin resistance. The SH-SY5Y-Ob-Rb human neuroblastoma cell line, transfected to express the Ob-Rb leptin receptor stably, was treated with 4-HNE, and leptin-induced signal transduction was analyzed. We found that 4-HNE dose- and time-dependently inhibited leptin-induced signal transducer and activator of transcription 3 (STAT3) phosphorylation, a major antiobesity signal of leptin. On the other hand, 4-HNE did not affect tyrosine phosphorylation of broad cellular proteins, suggesting that the inhibitory effect may be selective to leptin signaling. Mechanistically, 4-HNE induced the eukaryotic initiation factor 2α-CCAAT/enhancer-binding protein homologous protein arm of endoplasmic reticulum stress signaling, which may be involved in the pathogenesis of leptin resistance. Overall, these results suggest that 4-HNE may partly affect endoplasmic reticulum stress-induced unfolded protein response signaling and may be involved in the pathogenesis of leptin resistance.


Assuntos
Aldeídos/toxicidade , Inibidores de Cisteína Proteinase/toxicidade , Estresse do Retículo Endoplasmático/fisiologia , Leptina/metabolismo , Obesidade/metabolismo , Receptores para Leptina/metabolismo , Linhagem Celular Tumoral , Relação Dose-Resposta a Droga , Estresse do Retículo Endoplasmático/efeitos dos fármacos , Humanos , Leptina/antagonistas & inibidores
16.
Biochem Biophys Res Commun ; 508(2): 516-520, 2019 01 08.
Artigo em Inglês | MEDLINE | ID: mdl-30509487

RESUMO

Cells activate the unfolded protein response (UPR) to cope with endoplasmic reticulum (ER) stress. In the present study, we investigated the possible involvement of psychological stress on UPR induction in the mouse brain. When mice were exposed to immobilization stress for 8 h, XBP1 mRNA splicing was significantly induced in the hippocampus, cortex, hypothalamus, cerebellum, and brain stem. On the other hand, we did not observe any increase in XBP1 splicing in the liver, suggesting that this effect is specific to the brain. Stress-induced XBP1 splicing was attenuated 2 days after immobilization stress. We did not observe increases in any other UPR genes, such as CHOP or GRP78, in mouse brains after immobilization stress. These findings indicate an important specific role of XBP1 in response to psychological stress in the mouse brain.


Assuntos
Encéfalo/metabolismo , Splicing de RNA , Estresse Psicológico/genética , Proteína 1 de Ligação a X-Box/genética , Animais , Chaperona BiP do Retículo Endoplasmático , Imobilização/efeitos adversos , Camundongos , Resposta a Proteínas não Dobradas/genética , Proteína 1 de Ligação a X-Box/metabolismo
17.
Front Physiol ; 9: 1357, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30319453

RESUMO

It is known that endoplasmic reticulum (ER) and nucleus communicate with each other to cope with ER stress. However, the mechanisms through which extracellular transmission of ER stress occurs remain unexplored. When the ER stress-induced unfolded protein response (UPR) is activated, the X-box binding protein 1 (XBP1) mRNA is spliced by inositol-requiring enzyme-1α (IRE1α) to produce the spliced form of XBP1 (sXBP1). In the present study, we found that sXBP1 mRNA in the cell may be incorporated into the exosomes and was released extracellularly. We found that the ratio of the mRNA levels of sXBP1 to unspliced XBP1 (uXBP1) in the exosome was higher than that of cells in MIN6 mouse pancreatic ß cells. A similar effect was observed when XBP1 splicing was induced by overexpressing IRE1α in HEK293T cells. These results suggest that the incorporation of sXBP1 into the exosomes is a novel mechanism of UPR transmitted to extracellularly, which would be triggered when cells are exposed to stress.

18.
Biotechnol Lett ; 40(6): 915-922, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29619746

RESUMO

OBJECTIVE: The exposure of organelles, such as the endoplasmic reticulum (ER), Golgi apparatus (GA), and lysosomes, to stress activates death mechanisms. Recently, telomerase reverse transcriptase (TERT) has been shown to be involved in cell survival. However, the relationship between TERT and the stress responses is still unclear. Here, we aimed to clarify the possible mechanisms of action through which TERT promotes cell survival by studying its effect on the stresses faced by multiple organelles in human fibroblasts. RESULTS: We found that TERT enhanced the survival rate of cells under ER stress, regardless of ER stress inducers such as tunicamycin (protein glycosylation inhibitor), thapsigargin (Ca2+-ATPase inhibitor), brefeldin A (protein transport inhibitor), or dithiothreitol (disulfide bond formation inhibitor). We also found that TERT enhanced the survival rate of cells under GA and lysosomal stresses. CONCLUSION: Collectively, these results suggest that TERT suppresses cell stress and promotes cell survival via different mechanisms. These findings may offer new insights into the implications of TERT in the treatment of stress-induced conditions such as aging, obesity, and neurodegenerative diseases.


Assuntos
Estresse do Retículo Endoplasmático , Fibroblastos , Complexo de Golgi , Lisossomos , Telomerase , Linhagem Celular , Sobrevivência Celular/fisiologia , Estresse do Retículo Endoplasmático/genética , Estresse do Retículo Endoplasmático/fisiologia , Fibroblastos/metabolismo , Fibroblastos/fisiologia , Complexo de Golgi/genética , Complexo de Golgi/metabolismo , Humanos , Lisossomos/genética , Lisossomos/metabolismo , Estresse Fisiológico/genética , Estresse Fisiológico/fisiologia , Telomerase/genética , Telomerase/fisiologia
19.
Immun Inflamm Dis ; 6(1): 97-105, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-29094492

RESUMO

INTRODUCTION: Mast cells play an important role in allergic responses. METHODS: We herein demonstrated the mechanisms of inhibitory effect of adenine on IgE/antigen-induced degranulation and TNF-α release in mast cells. RESULTS: We found that these effects were dependent on the amino group of adenine because purine only weakly inhibited degranulation. Adenine also inhibited Ca2+ ionophore- and thapsigargin-induced degranulation, however, this inhibitory effect was weaker than that of the antigen. Therefore, the inhibitory effects of adenine on degranulation may be mediated before as well as after the Ca2+ raise under the antigen stimulus. Adenine inhibited antigen-induced Syk and the subsequent induction of AKT and ERK activation under FcϵRI-mediated signal. Adenine also attenuated antigen-induced increase in Ca2+ . Furthermore, adenine inhibited IgE/antigen-induced IKKα/ß activation, which is involved in degranulation. Finally, adenine protected mice against anaphylactic allergic responses in vivo. CONCLUSIONS: The present study revealed a key role of adenine in the attenuation of allergic responses through the inhibition of Syk-mediated signal transduction and IKK-mediated degranulation.


Assuntos
Adenina/farmacologia , Sinalização do Cálcio/efeitos dos fármacos , Hipersensibilidade/tratamento farmacológico , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Mastócitos/imunologia , Animais , Sinalização do Cálcio/imunologia , Hipersensibilidade/imunologia , Hipersensibilidade/patologia , Sistema de Sinalização das MAP Quinases/imunologia , Mastócitos/patologia , Camundongos , Proteína Oncogênica v-akt/imunologia , Ratos , Quinase Syk/imunologia
20.
Yakugaku Zasshi ; 137(12): 1517-1531, 2017.
Artigo em Japonês | MEDLINE | ID: mdl-29199260

RESUMO

A seminar titled "Implementation and evaluation of genetic testing of lifestyle-related disease genes" was held for pharmacists, medical clerks, and clerks of pharmacy insurance, with the aim of holding seminars led by pharmacists for the general public (including patients) in the future. The subject of the seminar was single nucleotide polymorphisms in obesity-related genes and alcohol metabolism-related genes. The purpose of the seminar was to contribute to the prevention of lifestyle-related diseases of the general public. We evaluated it by administering a questionnaire to the participants before and after the seminar. After the seminar, 55% of pharmacists answered that they would like to or would strongly like to participate in genetic testing (for lifestyle-related diseases and drug metabolism-related genes) of the general public. However, some participants did not wish to do so. A customer satisfaction (CS) analysis found that this was mainly because they did not want to know the results of genetic testing of others, which they felt should be private. Most (82%) of the pharmacists answered that assistance and advice was "very necessary" or "necessary" in the participation of genetic testing. These findings show that collaboration between pharmacies and universities will be important for future seminars to the general public.


Assuntos
Testes Genéticos , Seguro de Serviços Farmacêuticos , Colaboração Intersetorial , Estilo de Vida , Farmácia , Universidades , Álcool Desidrogenase/genética , Educação em Saúde/tendências , Humanos , Obesidade/genética , Farmacêuticos , Polimorfismo de Nucleotídeo Único , Inquéritos e Questionários
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