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1.
PLoS Negl Trop Dis ; 14(7): e0008447, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32730343

RESUMO

Only a single drug against schistosomiasis is currently available and new drug development is urgently required but very few drug targets have been validated and characterised. However, regulatory systems including cyclic nucleotide metabolism are emerging as primary candidates for drug discovery. Here, we report the cloning of ten cyclic nucleotide phosphodiesterase (PDE) genes of S. mansoni, out of a total of 11 identified in its genome. We classify these PDEs by homology to human PDEs. Male worms displayed higher expression levels for all PDEs, in mature and juvenile worms, and schistosomula. Several functional complementation approaches were used to characterise these genes. We constructed a Trypanosoma brucei cell line in which expression of a cAMP-degrading PDE complements the deletion of TbrPDEB1/B2. Inhibitor screens of these cells expressing only either SmPDE4A, TbrPDEB1 or TbrPDEB2, identified highly potent inhibitors of the S. mansoni enzyme that elevated the cellular cAMP concentration. We further expressed most of the cloned SmPDEs in two pde1Δ/pde2Δ strains of Saccharomyces cerevisiae and some also in a specialised strain of Schizosacharomyces pombe. Five PDEs, SmPDE1, SmPDE4A, SmPDE8, SmPDE9A and SmPDE11 successfully complemented the S. cerevisiae strains, and SmPDE7var also complemented to a lesser degree, in liquid culture. SmPDE4A, SmPDE8 and SmPDE11 were further assessed in S. pombe for hydrolysis of cAMP and cGMP; SmPDE11 displayed considerable preferrence for cGMP over cAMP. These results and tools enable the pursuit of a rigorous drug discovery program based on inhibitors of S. mansoni PDEs.


Assuntos
Clonagem Molecular , Regulação Enzimológica da Expressão Gênica/fisiologia , Proteínas de Helminto/metabolismo , Diester Fosfórico Hidrolases/genética , Schistosoma mansoni/enzimologia , Schistosoma mansoni/genética , Animais , Linhagem Celular , Deleção de Genes , Perfilação da Expressão Gênica , Genoma Helmíntico , Proteínas de Helminto/genética , Masculino , Camundongos , Filogenia , Trypanosoma brucei brucei , Leveduras
2.
Invest Ophthalmol Vis Sci ; 61(5): 29, 2020 05 11.
Artigo em Inglês | MEDLINE | ID: mdl-32421147

RESUMO

Purpose: Matrix metalloproteinases (MMPs) are involved in extracellular matrix (ECM) maintenance and remodeling. The present study aimed to determine whether transforming growth factor (TGF)-ß2 regulates MMP-2 and MMP-9 levels and activities in astrocytes derived from the optic nerve head (ONH) and the role of statins in such modulation. Methods: Primary astrocytes cultured from the lamina cribrosa of human donor ONHs were incubated with three types of statins (5 µg/mL) for 1 hour followed by recombinant TGF-ß2 (5 ng/mL) for various periods to test their effects. Levels and activities of MMP-2 and MMP-9 in astrocytes in vitro were determined by western blotting and zymography, respectively. Levels of phosphorylated myosin phosphatase target subunit 1 (MYPT1) in astrocyte lysates were determined by western blotting, and those of phosphorylated myosin light chain (MLC) were determined by western blotting and immunocytochemistry. Results: MMP-2 and MMP-9 levels were upregulated by TGF-ß2 in human ONH astrocytes. Prior incubation with simvastatin, lovastatin, and atorvastatin inhibited TGF-ß2-mediated MMP-2 and MMP-9 expression and activities. Prior incubation with statins downregulated the TGF-ß2-induced phosphorylation of MYPT1 and MLC, which are downstream substrates of RhoA and ROCKs. Conclusions: Statins inhibited the TGF-ß2-mediated regulation of MMP-2 and MMP-9 by inhibiting the RhoA/ROCK signaling pathway. Considering the role of MMP in ECM remodeling, the present findings support the notion that statins positively impact ECM remodeling within the ONH.


Assuntos
Astrócitos/efeitos dos fármacos , Regulação Enzimológica da Expressão Gênica/fisiologia , Inibidores de Hidroximetilglutaril-CoA Redutases/farmacologia , Metaloproteinase 2 da Matriz/genética , Metaloproteinase 9 da Matriz/genética , Fator de Crescimento Transformador beta2/antagonistas & inibidores , Quinases Associadas a rho/antagonistas & inibidores , Proteína rhoA de Ligação ao GTP/antagonistas & inibidores , Adulto , Astrócitos/enzimologia , Atorvastatina/farmacologia , Western Blotting , Células Cultivadas , Feminino , Humanos , Imuno-Histoquímica , Lovastatina/farmacologia , Masculino , Metaloproteinase 2 da Matriz/metabolismo , Metaloproteinase 9 da Matriz/metabolismo , Pessoa de Meia-Idade , Fosfatase de Miosina-de-Cadeia-Leve/metabolismo , Disco Óptico/citologia , Fosforilação , Transdução de Sinais/efeitos dos fármacos , Sinvastatina/farmacologia , Fator de Crescimento Transformador beta2/farmacologia
3.
Proc Natl Acad Sci U S A ; 117(17): 9497-9507, 2020 04 28.
Artigo em Inglês | MEDLINE | ID: mdl-32300005

RESUMO

Nitric oxide (NO) produced by endothelial nitric oxide synthase (eNOS) is a critical mediator of vascular function. eNOS is tightly regulated at various levels, including transcription, co- and posttranslational modifications, and by various protein-protein interactions. Using stable isotope labeling with amino acids in cell culture (SILAC) and mass spectrometry (MS), we identified several eNOS interactors, including the protein plasminogen activator inhibitor-1 (PAI-1). In cultured human umbilical vein endothelial cells (HUVECs), PAI-1 and eNOS colocalize and proximity ligation assays demonstrate a protein-protein interaction between PAI-1 and eNOS. Knockdown of PAI-1 or eNOS eliminates the proximity ligation assay (PLA) signal in endothelial cells. Overexpression of eNOS and HA-tagged PAI-1 in COS7 cells confirmed the colocalization observations in HUVECs. Furthermore, the source of intracellular PAI-1 interacting with eNOS was shown to be endocytosis derived. The interaction between PAI-1 and eNOS is a direct interaction as supported in experiments with purified proteins. Moreover, PAI-1 directly inhibits eNOS activity, reducing NO synthesis, and the knockdown or antagonism of PAI-1 increases NO bioavailability. Taken together, these findings place PAI-1 as a negative regulator of eNOS and disruptions in eNOS-PAI-1 binding promote increases in NO production and enhance vasodilation in vivo.


Assuntos
Regulação Enzimológica da Expressão Gênica/fisiologia , Óxido Nítrico Sintase Tipo III/metabolismo , Inibidor 1 de Ativador de Plasminogênio/metabolismo , Disponibilidade Biológica , Linhagem Celular , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Células Endoteliais da Veia Umbilical Humana , Humanos , Óxido Nítrico , Óxido Nítrico Sintase Tipo III/genética , Piperazinas/farmacologia , Inibidor 1 de Ativador de Plasminogênio/genética , Ligação Proteica , Vasodilatação/efeitos dos fármacos , Vasodilatação/fisiologia , para-Aminobenzoatos/farmacologia
4.
Diabetes ; 69(6): 1178-1192, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32312867

RESUMO

Lipid droplets (LDs) are frequently increased when excessive lipid accumulation leads to cellular dysfunction. Distinct from mouse ß-cells, LDs are prominent in human ß-cells. However, the regulation of LD mobilization (lipolysis) in human ß-cells remains unclear. We found that glucose increases lipolysis in nondiabetic human islets but not in islets in patients with type 2 diabetes (T2D), indicating dysregulation of lipolysis in T2D islets. Silencing adipose triglyceride lipase (ATGL) in human pseudoislets with shRNA targeting ATGL (shATGL) increased triglycerides (TGs) and the number and size of LDs, indicating that ATGL is the principal lipase in human ß-cells. In shATGL pseudoislets, biphasic glucose-stimulated insulin secretion (GSIS), and insulin secretion to 3-isobutyl-1-methylxanthine and KCl were all reduced without altering oxygen consumption rate compared with scramble control. Like human islets, INS1 cells showed visible LDs, glucose-responsive lipolysis, and impairment of GSIS after ATGL silencing. ATGL-deficient INS1 cells and human pseudoislets showed reduced SNARE protein syntaxin 1a (STX1A), a key SNARE component. Proteasomal degradation of Stx1a was accelerated likely through reduced palmitoylation in ATGL-deficient INS1 cells. Therefore, ATGL is responsible for LD mobilization in human ß-cells and supports insulin secretion by stabilizing STX1A. The dysregulated lipolysis may contribute to LD accumulation and ß-cell dysfunction in T2D islets.


Assuntos
Células Secretoras de Insulina/fisiologia , Lipase/metabolismo , Gotículas Lipídicas/fisiologia , Sintaxina 1/metabolismo , Animais , Regulação para Baixo , Regulação Enzimológica da Expressão Gênica/fisiologia , Humanos , Insulina/metabolismo , Lipase/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Oxigênio/metabolismo , Consumo de Oxigênio , Sintaxina 1/genética
5.
Diabetes ; 69(6): 1149-1163, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32312870

RESUMO

Clinical studies have shown a link between hyperuricemia (HU) and diabetes, while the exact effect of soluble serum urate on glucose metabolism remains elusive. This study aims to characterize the glucose metabolic phenotypes and investigate the underlying molecular mechanisms using a novel spontaneous HU mouse model in which the uricase (Uox) gene is absent. In an attempt to study the role of HU in glycometabolism, we implemented external stimulation on Uox knockout (KO) and wild-type (WT) males with a high-fat diet (HFD) and/or injections of multiple low-dose streptozotocin (MLD-STZ) to provoke the potential role of urate. Notably, while Uox-KO mice developed glucose intolerance in the basal condition, no mice spontaneously developed diabetes, even with aging. HFD-fed Uox-KO mice manifested similar insulin sensitivity compared with WT controls. HU augmented the existing glycometabolism abnormality induced by MLD-STZ and eventually led to diabetes, as evidenced by the increased random glucose. Reduced ß-cell masses and increased terminal deoxynucleotidyl TUNEL-positive ß-cells suggested that HU-mediated diabetes was cell death dependent. However, urate-lowering therapy (ULT) cannot ameliorate the diabetes incidence or reverse ß-cell apoptosis with significance. ULT displayed a significant therapeutic effect of HU-crystal-associated kidney injury and tubulointerstitial damage in diabetes. Moreover, we present transcriptomic analysis of isolated islets, using Uox-KO versus WT mice and streptozotocin-induced diabetic WT (STZ-WT) versus diabetic Uox-KO (STZ-KO) mice. Shared differentially expressed genes of HU primacy revealed Stk17ß is a possible target gene in HU-related ß-cell death. Together, this study suggests that HU accelerates but does not cause diabetes by inhibiting islet ß-cell survival.


Assuntos
Diabetes Mellitus/etiologia , Glucose/metabolismo , Hiperuricemia/complicações , Células Secretoras de Insulina/fisiologia , Urato Oxidase/metabolismo , Animais , Apoptose , Área Sob a Curva , Glicemia , Diabetes Mellitus Experimental , Dieta Hiperlipídica , Gorduras na Dieta/administração & dosagem , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Regulação Enzimológica da Expressão Gênica/fisiologia , Homeostase , Insulina/sangue , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Urato Oxidase/genética
6.
Diabetes ; 69(6): 1248-1263, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32169892

RESUMO

Conceivably, upregulation of myo-inositol oxygenase (MIOX) is associated with altered cellular redox. Its promoter includes oxidant-response elements, and we also discovered binding sites for XBP1, a transcription factor of endoplasmic reticulum (ER) stress response. Previous studies indicate that MIOX's upregulation in acute tubular injury is mediated by oxidant and ER stress. Here, we investigated whether hyperglycemia leads to accentuation of oxidant and ER stress while these boost each other's activities, thereby augmenting tubulointerstitial injury/fibrosis. We generated MIOX-overexpressing transgenic (MIOX-TG) and MIOX knockout (MIOX-KO) mice. A diabetic state was induced by streptozotocin administration. Also, MIOX-KO were crossbred with Ins2 Akita to generate Ins2 Akita/KO mice. MIOX-TG mice had worsening renal functions with kidneys having increased oxidant/ER stress, as reflected by DCF/dihydroethidium staining, perturbed NAD-to-NADH and glutathione-to-glutathione disulfide ratios, increased NOX4 expression, apoptosis and its executionary molecules, accentuation of TGF-ß signaling, Smads and XBP1 nuclear translocation, expression of GRP78 and XBP1 (ER stress markers), and accelerated tubulointerstitial fibrosis. These changes were not seen in MIOX-KO mice. Interestingly, such changes were remarkably reduced in Ins2 Akita/KO mice and, likewise, in vitro experiments with XBP1 siRNA. These findings suggest that MIOX expression accentuates, while its deficiency shields kidneys from, tubulointerstitial injury by dampening oxidant and ER stress, which mutually enhance each other's activity.


Assuntos
Nefropatias Diabéticas/metabolismo , Regulação Enzimológica da Expressão Gênica/fisiologia , Inositol Oxigenase/metabolismo , Animais , Apoptose , Glicemia , Linhagem Celular , Diabetes Mellitus Experimental , Humanos , Hiperglicemia , Inositol Oxigenase/genética , Insulina/genética , Insulina/metabolismo , Rim/citologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Mutação , Espécies Reativas de Oxigênio
7.
Plant Mol Biol ; 103(3): 355-371, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32193789

RESUMO

KEYMESSAGE: Biphasic starch granules in maize ae mutant underwent the weak to strong SBEIIb-defective effect during endosperm development, leading to no birefringence in their exterior due to extended long branch-chains of amylopectin. Biphasic starch granules are usually detected regionally in cereal endosperm lacking starch branching enzyme (SBE). However, their molecular structure, formation mechanism, and regional distribution are unclear. In this research, biphasic starch granules were observed in the inner region of crown endosperm of maize ae mutant, and had poorly oriented structure with comb-like profiles in their exterior. The inner endosperm (IE) rich in biphasic starch granules and outer endosperm (OE) without biphasic starch granules were investigated. The starch had lower amylose content and higher proportion of long branch-chains of amylopectin in IE than in OE, and the exterior of biphasic starch granules had less amylose and more long branch-chains of amylopectin than the interior. Compared with OE, the expression pattern of starch synthesis related enzymes changed significantly in IE. The granule-bound starch synthase I activity within biphasic starch granules decreased slightly. The IE experienced more severe hypoxic stress than OE, and the up-regulated anaerobic respiration pathway indicated an increase in carbon consumption. The starch in IE underwent the SBEIIb-defective effect from weak to strong due to the lack of sufficient carbon inflow, leading to the formation of biphasic starch granules and their regional distribution in endosperm. The results provided information for understanding the biphasic starch granules.


Assuntos
Enzima Ramificadora de 1,4-alfa-Glucana/metabolismo , Regulação Enzimológica da Expressão Gênica/fisiologia , Regulação da Expressão Gênica de Plantas/fisiologia , Amido/metabolismo , Zea mays/enzimologia , Enzima Ramificadora de 1,4-alfa-Glucana/classificação , Enzima Ramificadora de 1,4-alfa-Glucana/genética , Endosperma/enzimologia , Endosperma/ultraestrutura , Amido/ultraestrutura
8.
Proc Natl Acad Sci U S A ; 117(8): 4071-4077, 2020 02 25.
Artigo em Inglês | MEDLINE | ID: mdl-32041886

RESUMO

Copper-containing nitrite reductases (CuNIRs) transform nitrite to gaseous nitric oxide, which is a key process in the global nitrogen cycle. The catalytic mechanism has been extensively studied to ultimately achieve rational control of this important geobiochemical reaction. However, accumulated structural biology data show discrepancies with spectroscopic and computational studies; hence, the reaction mechanism is still controversial. In particular, the details of the proton transfer involved in it are largely unknown. This situation arises from the failure of determining positions of hydrogen atoms and protons, which play essential roles at the catalytic site of CuNIRs, even with atomic resolution X-ray crystallography. Here, we determined the 1.50 Šresolution neutron structure of a CuNIR from Geobacillus thermodenitrificans (trimer molecular mass of ∼106 kDa) in its resting state at low pH. Our neutron structure reveals the protonation states of catalytic residues (deprotonated aspartate and protonated histidine), thus providing insights into the catalytic mechanism. We found that a hydroxide ion can exist as a ligand to the catalytic Cu atom in the resting state even at a low pH. This OH-bound Cu site is unexpected from previously given X-ray structures but consistent with a reaction intermediate suggested by computational chemistry. Furthermore, the hydrogen-deuterium exchange ratio in our neutron structure suggests that the intramolecular electron transfer pathway has a hydrogen-bond jump, which is proposed by quantum chemistry. Our study can seamlessly link the structural biology to the computational chemistry of CuNIRs, boosting our understanding of the enzymes at the atomic and electronic levels.


Assuntos
Cobre/química , Cristalografia/métodos , Geobacillus/enzimologia , Nitrito Redutases/química , Nitrito Redutases/metabolismo , Domínio Catalítico , Cristalização , Regulação Bacteriana da Expressão Gênica/fisiologia , Regulação Enzimológica da Expressão Gênica/fisiologia , Geobacillus/genética , Geobacillus/metabolismo , Modelos Moleculares , Nitrito Redutases/genética , Conformação Proteica
9.
Diabetes ; 69(5): 893-901, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32086288

RESUMO

An aging global population combined with sedentary lifestyles and unhealthy diets has contributed to an increasing incidence of obesity and type 2 diabetes. These metabolic disorders are associated with perturbations to nitric oxide (NO) signaling and impaired glucose metabolism. Dietary inorganic nitrate, found in high concentration in green leafy vegetables, can be converted to NO in vivo and demonstrates antidiabetic and antiobesity properties in rodents. Alongside tissues including skeletal muscle and liver, white adipose tissue is also an important physiological site of glucose disposal. However, the distinct molecular mechanisms governing the effect of nitrate on adipose tissue glucose metabolism and the contribution of this tissue to the glucose-tolerant phenotype remain to be determined. Using a metabolomic and stable-isotope labeling approach, combined with transcriptional analysis, we found that nitrate increases glucose uptake and oxidative catabolism in primary adipocytes and white adipose tissue of nitrate-treated rats. Mechanistically, we determined that nitrate induces these phenotypic changes in primary adipocytes through the xanthine oxidoreductase-catalyzed reduction of nitrate to NO and independently of peroxisome proliferator-activated receptor-α. The nitrate-mediated enhancement of glucose uptake and catabolism in white adipose tissue may be a key contributor to the antidiabetic effects of this anion.


Assuntos
Tecido Adiposo Branco/efeitos dos fármacos , Tecido Adiposo Branco/metabolismo , Glucose/metabolismo , Nitratos/farmacologia , Óxido Nítrico/metabolismo , Xantina Desidrogenase/metabolismo , Adipócitos/efeitos dos fármacos , Adipócitos/metabolismo , Animais , Células Cultivadas , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Regulação Enzimológica da Expressão Gênica/fisiologia , Masculino , Metabolismo , Nitratos/administração & dosagem , Oxirredução , Ratos , Ratos Wistar
10.
Am J Physiol Renal Physiol ; 318(3): F628-F638, 2020 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-31904289

RESUMO

Excessive compensatory nephron hypertrophy (CNH) has been implicated in setting the stage for progressive nephron damage. Lack of a class III phosphatidylinositol 3-kinase (Pik3c3) inhibitor suitable for using in animals and lack of a Pik3c3-deficient animal model preclude the possibility of conclusively defining a role for Pik3c3 in CNH in previous studies. Here, we report that insertion of an Frt-flanked PGK-Neo cassette into intron 19 of the mouse Pik3c3 gene resulted in a hypomorphic allele. This allowed us to create a unique mouse model and provide the first definitive genetic evidence demonstrating whether Pik3c3 is essential for the regulation of CNH. Our results indicate that homozygous Pik3c3 hypomorphic (Pik3c3Hypo/Hypo) mice express significantly low levels of Pik3c3 than heterozygous Pik3c3 hypomorphic (Pik3c3Hypo/WT) littermates, which already express a lower level of Pik3c3 than wild-type (Pik3c3WT/WT) littermates. Interestingly, after unilateral nephrectomy (UNX), Pik3c3Hypo/Hypo mice develop a significantly lower degree of CNH than Pik3c3WT/WT mice and Pik3c3Hypo/WT mice, as revealed by measurement of kidney weight, kidney-to-body weight ratio, renal protein-to-DNA ratio, and morphometric analysis of proximal tubular and glomerular size. Mechanistically, UNX-induced mammalian target of rapamycin complex 1 (mTORC1) signaling to phosphorylation of ribosomal protein S6 (rpS6) in the remaining kidney was markedly inhibited in Pik3c3 hypomorphic mice. In conclusion, the present study reports a Pik3c3 hypomorphic mouse model and provides the first definitive evidence that Pik3c3 controls the degree of compensatory nephron hypertrophy. In addition, our signaling data provide the first definitive in vivo proof that Pik3c3 functions upstream of the mTORC1-S6 kinase 1-rpS6 pathway in the regulation of compensatory nephron hypertrophy.


Assuntos
Classe III de Fosfatidilinositol 3-Quinases/metabolismo , Néfrons/patologia , Animais , Classe III de Fosfatidilinositol 3-Quinases/genética , Regulação Enzimológica da Expressão Gênica/fisiologia , Hipertrofia , Íntrons/genética , Alvo Mecanístico do Complexo 1 de Rapamicina/genética , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Camundongos , Mutagênese Insercional , Nefrectomia , Néfrons/metabolismo , Transdução de Sinais/fisiologia
11.
Am J Physiol Regul Integr Comp Physiol ; 318(1): R122-R134, 2020 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-31692367

RESUMO

Hypothalamic AMPK plays a major role in the regulation of whole body metabolism and energy balance. Present evidence has demonstrated that this canonical mechanism is evolutionarily conserved. Thus, recent data demonstrated that inhibition of AMPKα2 in fish hypothalamus led to decreased food intake and liver capacity to use and synthesize glucose, lipids, and amino acids. We hypothesize that a signal of abundance of nutrients from the hypothalamus controls hepatic metabolism. The vagus nerve is the most important link between the brain and the liver. We therefore examined in the present study whether surgical transection of the vagus nerve in rainbow trout is sufficient to alter the effect in liver of central inhibition of AMPKα2. Thus, we vagotomized (VGX) or not (Sham) rainbow trout and then intracerebroventricularly administered adenoviral vectors tagged with green fluorescent protein alone or linked to a dominant negative isoform of AMPKα2. The inhibition of AMPKα2 led to reduced food intake in parallel with changes in the mRNA abundance of hypothalamic neuropeptides [neuropeptide Y (npy), agouti-related protein 1 (agrp1), and cocaine- and amphetamine-related transcript (cartpt)] involved in food intake regulation. Central inhibition of AMPKα2 resulted in the liver having decreased capacity to use and synthesize glucose, lipids, and amino acids. Notably, these effects mostly disappeared in VGX fish. These results support the idea that autonomic nervous system actions mediate the actions of hypothalamic AMPKα2 on liver metabolism. Importantly, this evidence indicates that the well-established role of hypothalamic AMPK in energy balance is a canonical evolutionarily preserved mechanism that is also present in the fish lineage.


Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Metabolismo Energético/fisiologia , Hipotálamo/enzimologia , Fígado/metabolismo , Oncorhynchus mykiss/fisiologia , Nervo Vago/fisiologia , Proteínas Quinases Ativadas por AMP/genética , Adenoviridae , Animais , Comportamento Alimentar/fisiologia , Regulação Enzimológica da Expressão Gênica/fisiologia , Fígado/inervação , Vagotomia
12.
Vision Res ; 166: 43-51, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31855667

RESUMO

A correlation is known to exist between visual sensitivity and oscillations in red opsinand rhodopsin gene expression in zebrafish, both regulated by the clock gene. This indicates that an endogenous circadian clock regulates behavioural visual sensitivity, apart from the regulation exerted by the pineal organ. However, the specific mechanisms for cones (photopic vision) and rods (scotopic vision) are poorly understood. In this work, we performed gene expression, cosinor and immunohistochemical analyses to investigate other key genes involved in light perception, encoding the different subunits of phosphodiesterase pde6 and transducin GαT, in constant lighting conditions and compared to normal light-dark conditions. We found that cones display prominent circadian oscillations in mRNA levels for the inhibitory subunit gene pde6ha that could contribute to the regulation of photopic sensitivity by preventing overstimulation in photopic conditions. In rods, the mRNA levels of the inhibitory subunit gene pde6ga oscillate under normal conditions and dampen down in constant light but continue oscillating in constant darkness. There is an increase in total relative expression for pde6gb in constant conditions. These observations, together with previous data, suggest a complex regulation of the scotopic sensitivity involving endogenous and non-endogenous components, possibly present also in other teleost species. The GαT genes do not display mRNA oscillations and therefore may not be essential for the circadian regulation of photosensitivity. In summary, our results support different regulation for the zebrafish photopic and scotopic sensitivities and suggest circadian regulation of pde6ha as a key factor regulating photopic sensitivity, while the regulatory mechanisms in rods appear to be more complex.


Assuntos
Ritmo Circadiano/fisiologia , Visão de Cores/fisiologia , Nucleotídeo Cíclico Fosfodiesterase do Tipo 6/genética , Regulação Enzimológica da Expressão Gênica/fisiologia , Visão Noturna/fisiologia , Células Fotorreceptoras de Vertebrados/enzimologia , Proteínas de Peixe-Zebra/genética , Animais , RNA Mensageiro/genética , Reação em Cadeia da Polimerase em Tempo Real , Peixe-Zebra
13.
J Cell Physiol ; 235(1): 166-175, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31180589

RESUMO

The pancreatic islets of Langerhans, mainly formed by glucagon-producing α-cells and insulin-producing ß-cells, are critical for glucose homeostasis. Insulin and glucagon oppositely modulate blood glucose levels in health, but a combined decline in insulin secretion together with increased glucagon secretion contribute to hyperglycemia in diabetes. Despite this bi-hormonal dysregulation, most studies have focused on insulin secretion and much less is known about glucagon secretion. Therefore, a deeper understanding of α-cell metabolism and glucagon secretion is of great interest. Here, we show that phosphoenolpyruvate carboxykinase (PCK1), an essential cataplerotic enzyme involved in metabolism and long considered to be absent from the pancreatic islet, is expressed in pancreatic α-cells of both murine and human. Furthermore, PCK1 transcription is induced by fasting and diabetes in rat pancreas, which indicates that the PCK1 activity is required for α-cell adaptation to different metabolic states. To our knowledge, this is the first evidence implicating PCK1 expression in α-cell metabolism.


Assuntos
Regulação Enzimológica da Expressão Gênica/fisiologia , Células Secretoras de Glucagon/enzimologia , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Fosfoenolpiruvato Carboxiquinase (GTP)/metabolismo , Animais , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/genética , Masculino , Camundongos , Pâncreas/enzimologia , Pâncreas/metabolismo , Fosfoenolpiruvato Carboxiquinase (GTP)/genética , Ratos
14.
J Cell Physiol ; 235(1): 114-127, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31347175

RESUMO

Myosin phosphatase-Rho interacting protein (p116Rip ) was originally found as a RhoA-binding protein. Subsequent studies by us and others revealed that p116Rip facilitates myosin light chain phosphatase (MLCP) activity through direct and indirect manners. However, it is unclear how p116Rip regulates myosin phosphatase activity in cells. To elucidate the role of p116Rip in cellular contractile processes, we suppressed the expression of p116Rip by RNA interference in human airway smooth muscle cells (HASMCs). We found that knockdown of p116Rip in HASMCs led to increased di-phosphorylated MLC (pMLC), that is phosphorylation at both Ser19 and Thr18. This was because of a change in the interaction between MLCP and myosin, but not an alteration of RhoA/ROCK signaling. Attenuation of Zipper-interacting protein kinase (ZIPK) abolished the increase in di-pMLC, suggesting that ZIPK is involved in this process. Moreover, suppression of p116Rip expression in HASMCs substantially increased the histamine-induced collagen gel contraction. We also found that expression of the p116Rip was decreased in the airway smooth muscle tissue from asthmatic patients compared with that from non-asthmatic patients, suggesting a potential role of p116Rip expression in asthma pathogenesis.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Miócitos de Músculo Liso/fisiologia , Fosfatase de Miosina-de-Cadeia-Leve/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/genética , Adolescente , Adulto , Colforsina/farmacologia , Feminino , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Regulação Enzimológica da Expressão Gênica/fisiologia , Histamina/farmacologia , Humanos , Masculino , Pessoa de Meia-Idade , Miócitos de Músculo Liso/efeitos dos fármacos , Fosfatase de Miosina-de-Cadeia-Leve/genética , Adulto Jovem
15.
J Antibiot (Tokyo) ; 73(3): 141-151, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31853029

RESUMO

Streptomyces sp. CHI39, isolated from a rock soil sample, is a producer of abyssomicin I. The taxonomic status was clarified by a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences showed that the strain was closely related to Streptomyces fragilis, with similarity of 99.9%. Strain CHI39 comprised LL-diaminopimelic acid, glutamic acid, glycine, and alanine in its peptidoglycan. The predominant menaquinones were MK-9(H6), and major fatty acids were anteiso-C15:0, anteiso-C17:0, and iso-C16:0. The chemotaxonomic features matched those described for the genus Streptomyces. Genome sequencing was conducted for strain CHI39 and S. fragilis NBRC 12862T. The results of digital DNA-DNA hybridization along with differences in phenotypic characteristics between the strains suggested strain CHI39 to be a novel species, for which Streptomyces abyssomicinicus sp. nov. is proposed; the type strain is CHI39T (=NBRC 110469T). Next, we surveyed polyketide synthase (PKS) and nonribosomal peptide synthetase (NRPS) gene clusters in genomes of S. abyssomicinicus CHI39T and S. fragilis NBRC 12862T. These strains encoded 9 and 12 clusters, respectively, among which only four clusters were shared between them while the others are specific in each strain. This suggests that strains classified to distinct species each harbor many specific secondary metabolite-biosynthetic pathways even if the strains are taxonomically close.


Assuntos
Regulação Bacteriana da Expressão Gênica/fisiologia , Regulação Enzimológica da Expressão Gênica/fisiologia , Peptídeo Sintases/metabolismo , Policetídeo Sintases/metabolismo , Streptomyces/enzimologia , Compostos Bicíclicos Heterocíclicos com Pontes , Família Multigênica , Peptídeo Sintases/genética , Policetídeo Sintases/genética , Streptomyces/genética
16.
Artigo em Inglês | MEDLINE | ID: mdl-31465878

RESUMO

This study was conducted to characterise the muscle-specific gene expression, energy metabolism level and growth rates of Atlantic salmon Salmo salar L. reared under different photoperiod regimes. The effects of two photoperiod regimes - LD 16:8 (16 h light:8 h dark) and LD 24:0 (24 h light:0 h dark) over a period of 3 months (August to October) on growth, energy metabolism enzyme activities (cytochrome c oxidase, COX; lactate dehydrogenase, LDH; and aldolase) and the gene expression levels of myogenic regulatory factors (MRFs - MyoD1 paralogues (MyoD1a, MyoD1b, MyoD1c), Myf5, MyoG), myostatin paralogues (MSTN-1a, MSTN-1b, MSTN-2a) and the fast skeletal myosin heavy chain (MyHC) in the muscles of Atlantic salmon underyearling fry (0+) were investigated. The experiment was conducted in a fish hatchery with natural variations in water temperature. The results were compared with those obtained in salmon reared under the lighting conditions of a fish hatchery (HL, hatchery lighting). The results revealed that the fry reared under constant light (LD 24:0) grew faster and were bigger at the end of the experiment. Fishes reared within the photoperiod regime LD 16:8 had a lower growth rate. COX activity was lower in fish under the LD 16:8 regime compared with the LD 24:0 group. The LDH and aldolase enzyme activities were higher in the group with constant light in comparison to control in the beginning of September. The expression level for all of the genes studied variated during the duration of the experiment, and MyHC, MyoG, MyoD1a and Myf5 expression depended on the light regime as well. The more noticeable changes in gene expression occurred in October. The MyHC and MyoG mRNA levels increased, accompanied by MyD1c gene expression, in both groups that had additional lighting (LD 16:8 and LD24:0) at the beginning of October and were higher than the HL group. In the HL group, the elevation of MyHC and MyoG mRNA was gradual during October, but there was a sharp increase in Myf5 expression at the beginning of October. MyoD1 paralogues differently expressed during the experiment. The MyoD1a mRNA level was elevated at the end of October along with MyHC and MyoG expression, but MyoD1b and MyoD1c mRNA levels decreased along with Myf5 gene expression. The expression of MSTN paralogues were elevated with increases in MyHC and MRFs transcripts. These findings show that constant light has a positive effect on the growth rate of salmon, affecting the aerobic and anaerobic capacity in their muscles. The alterations in muscle-specific gene expression between the groups with different light indicated that the mechanisms for regulating muscle growth processes in fish depend on photoperiod duration.


Assuntos
Proteínas de Peixes/biossíntese , Regulação Enzimológica da Expressão Gênica/fisiologia , Proteínas Musculares/biossíntese , Músculo Esquelético/enzimologia , Salmo salar/metabolismo , Animais
17.
Artigo em Inglês | MEDLINE | ID: mdl-31525459

RESUMO

As the first marine teleost demonstrated to biosynthesize long-chain polyunsaturated fatty acids (LC-PUFAs) from C18 precursors such as linoleic acid (LOA, 18:2n-6) and α-linolenic acid (ALA, 18:3n-3), the rabbitfish (Siganus canaliculatus) contains the complete enzymatic system for LC-PUFA biosynthesis, including Δ6/Δ5 fatty acid desaturase (Fad), Δ4 Fad, and elongase 5 (Elovl5). Previously, our group demonstrated that hepatocyte nuclear factor 4α (Hnf4α) is a transcription factor (TF) for rabbitfish Δ4 fad and elovl5, and interacts with the core promoter of Δ6/Δ5 fad. To fully clarify the role of Hnf4α in the regulation of LC-PUFA biosynthesis, the present study aimed to explore the regulatory role of Hnf4α on Δ6/Δ5 fad gene expression. First, Hnf4α overexpression and agonist assays identified the Hnf4α response region in the Δ6/Δ5 fad core promoter as -456 bp to +51 bp. Bioinformatic analysis predicted four potential Hnf4α binding elements in the core promoter, which were confirmed by site-directed mutation and functional assays in a dual luciferase assay system. Moreover, the mRNA expression levels of hnf4α, Δ6/Δ5 fad, and Δ4 fad were significantly increased in the S. canaliculatus hepatocyte line (SCHL) cells after treatment with Hnf4α agonists (Alverine and Benfluorex) or its mRNA overexpression. By contrast, the expression levels of these three genes were markedly decreased after hnf4a small interfering RNA (siRNA) transfection. The results indicated that Hnf4α has a regulatory effect on rabbitfish Δ6/Δ5 fad gene transcription, identifying Hnf4α as a TF of Δ6/Δ5 fad in vertebrates for the first time.


Assuntos
Ácidos Graxos Dessaturases/biossíntese , Proteínas de Peixes/metabolismo , Peixes/metabolismo , Regulação Enzimológica da Expressão Gênica/fisiologia , Fator 4 Nuclear de Hepatócito/metabolismo , Linoleoil-CoA Desaturase/biossíntese , Animais , Ácidos Graxos Dessaturases/genética , Proteínas de Peixes/genética , Peixes/genética , Fator 4 Nuclear de Hepatócito/genética , Linoleoil-CoA Desaturase/genética
18.
Int J Mol Sci ; 20(23)2019 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-31766739

RESUMO

Chrysanthemum (Chrysanthemum morifolium (Ramat.) Kitamura) plants have great ornamental value, but their flowers can also be a source of pollen contamination. Previously, morphological and cytological studies have shown that anthers of some chrysanthemum cultivars such as 'Qx-115' fail to dehisce, although the underlying mechanism is largely unknown. In this study, we investigated the molecular basis of anther indehiscence in chrysanthemum via transcriptome analysis of a dehiscent cultivar ('Qx-097') and an indehiscent cultivar ('Qx-115'). We also measured related physiological indicators during and preceding the period of anther dehiscence. Our results showed a difference in pectinase accumulation and activity between the two cultivars during dehiscence. Detection of de-esterified pectin and highly esterified pectin in anthers during the period preceding anther dehiscence using LM19 and LM20 monoclonal antibodies showed that both forms of pectin were absent in the stomium region of 'Qx-097' anthers but were abundant in that of 'Qx-115' anthers. Analysis of transcriptome data revealed a significant difference in the expression levels of two transcription factor-encoding genes, CmLOB27 and CmERF72, between 'Qx-097' and 'Qx-115' during anther development. Transient overexpression of CmLOB27 and CmERF72 separately in tobacco leaves promoted pectinase biosynthesis. We conclude that CmLOB27 and CmERF72 are involved in the synthesis of pectinase, which promotes the degradation of pectin. Our results lay a foundation for further investigation of the role of CmLOB27 and CmERF72 transcription factors in the process of anther dehiscence in chrysanthemum.


Assuntos
Chrysanthemum , Flores , Perfilação da Expressão Gênica , Regulação Enzimológica da Expressão Gênica/fisiologia , Regulação da Expressão Gênica de Plantas/fisiologia , Pectinas , Proteínas de Plantas , Poligalacturonase , Chrysanthemum/enzimologia , Chrysanthemum/genética , Flores/enzimologia , Flores/genética , Pectinas/genética , Pectinas/metabolismo , Proteínas de Plantas/biossíntese , Proteínas de Plantas/genética , Poligalacturonase/biossíntese , Poligalacturonase/genética
19.
Zhongguo Xue Xi Chong Bing Fang Zhi Za Zhi ; 31(5): 510-512, 2019 Aug 16.
Artigo em Chinês | MEDLINE | ID: mdl-31713380

RESUMO

OBJECTIVE: To examine the effect of low temperature on trehalose and trehalase levels in Culex pipiens pallens. METHODS: The fourth instar larvae and female adult mosquitoes of Cx. pipiens pallens were exposed at 4 ℃ for 0, 1, 3, 6, 12, 18, 24 h and 0, 1, 3, 6, 12, 18, 24, 36, 48, 72 h, respectively. Then, the trehalose and trehalase contents were detected by enzyme-linked immunosorbent assay (ELISA) in mosquitoes. RESULTS: The contents of trehalose and trehalase significantly increased in the larval and female adult mosquitoes post-exposure to low temperature. The changing trend of trehalose levels was consistent in the larval and female adult mosquitoes, and the highest levels were (2.458 8 ± 0.379 2) mg/g and (2.825 7 ± 0.211 1) mg/g 3 h post-exposure to low temperature, respectively. The trehalose and trehalase levels fluctuated greatly within the first 6 h post-exposure to low temperature. Following adaptation for a period of time, the trehalose and trehalase levels remained at a relatively high level. CONCLUSIONS: Low temperature may induce the production of trehalose and trehalase in Cx. pipiens pallens, and the trehalose and trehalase may play an important role in the improvement of the cold resistance.


Assuntos
Culex , Temperatura , Trealase , Trealose , Animais , Culex/enzimologia , Culex/genética , Ensaio de Imunoadsorção Enzimática , Feminino , Regulação Enzimológica da Expressão Gênica/fisiologia , Larva , Trealase/metabolismo , Trealose/metabolismo
20.
PLoS One ; 14(10): e0213630, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31613897

RESUMO

During the stringent response, bacteria synthesize guanosine-3',5'-bis(diphosphate) (ppGpp) and guanosine-5'-triphosphate 3'-diphosphate (pppGpp), which act as secondary messengers to promote cellular survival and adaptation. (p)ppGpp 'alarmones' are synthesized and/or hydrolyzed by proteins belonging to the RelA/SpoT Homologue (RSH) family. Many bacteria also encode 'small alarmone synthetase' (SAS) proteins (e.g. RelP, RelQ) which may also be capable of synthesizing a third alarmone: guanosine-5'-phosphate 3'-diphosphate (pGpp). Here, we report the biochemical properties of the Rel (RSH), RelP and RelQ proteins from Staphylococcus aureus (Sa-Rel, Sa-RelP, Sa-RelQ, respectively). Sa-Rel synthesized pppGpp more efficiently than ppGpp, but lacked the ability to produce pGpp. Sa-Rel efficiently hydrolyzed all three alarmones in a Mn(II) ion-dependent manner. The removal of the C-terminal regulatory domain of Sa-Rel increased its rate of (p)ppGpp synthesis ca. 10-fold, but had negligible effects on its rate of (pp)pGpp hydrolysis. Sa-RelP and Sa-RelQ efficiently synthesized pGpp in addition to pppGpp and ppGpp. The alarmone-synthesizing abilities of Sa-RelQ, but not Sa-RelP, were allosterically-stimulated by the addition of pppGpp, ppGpp or pGpp. The respective (pp)pGpp-synthesizing activities of Sa-RelP/Sa-RelQ were compared and contrasted with SAS homologues from Enterococcus faecalis (Ef-RelQ) and Streptococcus mutans (Sm-RelQ, Sm-RelP). Results indicated that EF-RelQ, Sm-RelQ and Sa-RelQ were functionally equivalent; but exhibited considerable variations in their respective biochemical properties, and the degrees to which alarmones and single-stranded RNA molecules allosterically modulated their respective alarmone-synthesizing activities. The respective (pp)pGpp-synthesizing capabilities of Sa-RelP and Sm-RelP proteins were inhibited by pGpp, ppGpp and pppGpp. Our results support the premise that RelP and RelQ proteins may synthesize pGpp in addition to (p)ppGpp within S. aureus and other Gram-positive bacterial species.


Assuntos
Proteínas de Bactérias/biossíntese , Regulação Bacteriana da Expressão Gênica/fisiologia , Regulação Enzimológica da Expressão Gênica/fisiologia , Guanosina Pentafosfato/biossíntese , Staphylococcus aureus/metabolismo , Proteínas de Bactérias/genética , Guanosina Pentafosfato/genética , Staphylococcus aureus/genética , Streptococcus mutans/genética , Streptococcus mutans/metabolismo
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