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1.
EMBO Rep ; 24(10): e57090, 2023 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-37592911

RESUMO

The complex life cycle of the human malaria parasite, Plasmodium falciparum, is driven by specific transcriptional programs, but it is unclear how most genes are activated or silenced at specific times. There is an association between transcription and spatial organization; however, the molecular mechanisms behind genome organization are unclear. While P. falciparum lacks key genome-organizing proteins found in metazoans, it has all core components of the cohesin complex. To investigate the role of cohesin in P. falciparum, we functionally characterize the cohesin subunit Structural Maintenance of Chromosomes protein 3 (SMC3). SMC3 knockdown during early stages of the intraerythrocytic developmental cycle (IDC) upregulates a subset of genes involved in erythrocyte egress and invasion, which are normally expressed at later stages. ChIP-seq analyses reveal that during the IDC, SMC3 enrichment at the promoter regions of these genes inversely correlates with gene expression and chromatin accessibility. These data suggest that SMC3 binding contributes to the repression of specific genes until their appropriate time of expression, revealing a new mode of stage-specific gene repression in P. falciparum.

2.
EMBO Rep ; 20(4)2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30833341

RESUMO

Post-translational modifications of histone H3 N-terminal tails are key epigenetic regulators of virulence gene expression and sexual commitment in the human malaria parasite Plasmodium falciparum Here, we identify proteolytic clipping of the N-terminal tail of nucleosome-associated histone H3 at amino acid position 21 as a new chromatin modification. A cathepsin C-like proteolytic clipping activity is observed in nuclear parasite extracts. Notably, an ectopically expressed version of clipped histone H3, PfH3p-HA, is targeted to the nucleus and integrates into mononucleosomes. Furthermore, chromatin immunoprecipitation and next-generation sequencing analysis identified PfH3p-HA as being highly enriched in the upstream region of six genes that play a key role in DNA replication and repair: In these genes, PfH3p-HA demarcates a specific 1.5 kb chromatin island adjacent to the open reading frame. Our results indicate that, in P. falciparum, the process of histone clipping may precede chromatin integration hinting at preferential targeting of pre-assembled PfH3p-containing nucleosomes to specific genomic regions. The discovery of a protease-directed mode of chromatin organization in P. falciparum opens up new avenues to develop new anti-malarials.


Assuntos
Replicação do DNA , Histonas/metabolismo , Malária Falciparum/parasitologia , Nucleossomos/metabolismo , Plasmodium falciparum/fisiologia , Regiões 5' não Traduzidas , Sequência de Aminoácidos , Imunoprecipitação da Cromatina , Expressão Ectópica do Gene , Eritrócitos/parasitologia , Regulação da Expressão Gênica , Histonas/química , Histonas/genética , Humanos , Inibidores de Proteases/farmacologia , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas , Proteólise/efeitos dos fármacos
3.
J Biol Chem ; 290(18): 11537-46, 2015 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-25770211

RESUMO

Inasmuch as the neurohormone melatonin is synthetically derived from serotonin (5-HT), a close interrelationship between both has long been suspected. The present study reveals a hitherto unrecognized cross-talk mediated via physical association of melatonin MT2 and 5-HT2C receptors into functional heteromers. This is of particular interest in light of the "synergistic" melatonin agonist/5-HT2C antagonist profile of the novel antidepressant agomelatine. A suite of co-immunoprecipitation, bioluminescence resonance energy transfer, and pharmacological techniques was exploited to demonstrate formation of functional MT2 and 5-HT2C receptor heteromers both in transfected cells and in human cortex and hippocampus. MT2/5-HT2C heteromers amplified the 5-HT-mediated Gq/phospholipase C response and triggered melatonin-induced unidirectional transactivation of the 5-HT2C protomer of MT2/5-HT2C heteromers. Pharmacological studies revealed distinct functional properties for agomelatine, which shows "biased signaling." These observations demonstrate the existence of functionally unique MT2/5-HT2C heteromers and suggest that the antidepressant agomelatine has a distinctive profile at these sites potentially involved in its therapeutic effects on major depression and generalized anxiety disorder. Finally, MT2/5-HT2C heteromers provide a new strategy for the discovery of novel agents for the treatment of psychiatric disorders.


Assuntos
Melatonina/metabolismo , Multimerização Proteica , Receptor MT2 de Melatonina/química , Receptor 5-HT2C de Serotonina/química , Serotonina/metabolismo , Transdução de Sinais , Acetamidas/farmacologia , Arrestinas/metabolismo , Sinergismo Farmacológico , Regulação da Expressão Gênica/efeitos dos fármacos , Células HEK293 , Células HeLa , Humanos , Melatonina/farmacologia , Multimerização Proteica/efeitos dos fármacos , Estrutura Quaternária de Proteína , Transporte Proteico/efeitos dos fármacos , Receptor MT1 de Melatonina/metabolismo , Receptor MT2 de Melatonina/genética , Receptor MT2 de Melatonina/metabolismo , Receptor 5-HT2C de Serotonina/genética , Receptor 5-HT2C de Serotonina/metabolismo , Serotonina/farmacologia , Transdução de Sinais/efeitos dos fármacos , Ativação Transcricional/efeitos dos fármacos , Ativação Transcricional/genética , Fosfolipases Tipo C/metabolismo , beta-Arrestinas
4.
J Vet Pharmacol Ther ; 39(4): 356-62, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26896236

RESUMO

Meloxicam is a cyclooxygenase (COX) inhibitor with a higher selectivity for cyclooxygenase-2 (COX-2) than for cyclooxygenase-1 (COX-1). In the laboratory setting, this nonsteroidal anti-inflammatory drug (NSAID) is commonly selected for analgesia in mice and administered every 24 h. This study characterizes the plasma concentration achieved from a dose of 1.6 mg/kg of meloxicam administered once every 24 h subcutaneously for 72 h in male and female C57BL/6 mice. These values were compared, over time, to reference COX-2 inhibition constants for meloxicam. No significant differences in trough plasma concentrations were noted between genders. The plasma concentrations were below the COX-2 IC50 after 12 h. To maintain a plasma concentration at or above the COX-2 whole blood IC50, the study results suggest an administration frequency of every 12 h when using a dose of 1.6 mg/kg in C57BL/6 mice.


Assuntos
Analgesia/veterinária , Anti-Inflamatórios não Esteroides/farmacocinética , Tiazinas/farmacocinética , Tiazóis/farmacocinética , Analgesia/métodos , Animais , Anti-Inflamatórios não Esteroides/administração & dosagem , Anti-Inflamatórios não Esteroides/sangue , Esquema de Medicação , Feminino , Injeções Subcutâneas/veterinária , Masculino , Meloxicam , Camundongos , Camundongos Endogâmicos C57BL , Cuidados Pós-Operatórios/métodos , Cuidados Pós-Operatórios/veterinária , Fatores Sexuais , Suspensões , Tiazinas/administração & dosagem , Tiazinas/sangue , Tiazóis/administração & dosagem , Tiazóis/sangue
5.
Antimicrob Agents Chemother ; 59(2): 950-9, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25421480

RESUMO

Current antimalarials are under continuous threat due to the relentless development of drug resistance by malaria parasites. We previously reported promising in vitro parasite-killing activity with the histone methyltransferase inhibitor BIX-01294 and its analogue TM2-115. Here, we further characterize these diaminoquinazolines for in vitro and in vivo efficacy and pharmacokinetic properties to prioritize and direct compound development. BIX-01294 and TM2-115 displayed potent in vitro activity, with 50% inhibitory concentrations (IC50s) of <50 nM against drug-sensitive laboratory strains and multidrug-resistant field isolates, including artemisinin-refractory Plasmodium falciparum isolates. Activities against ex vivo clinical isolates of both P. falciparum and Plasmodium vivax were similar, with potencies of 300 to 400 nM. Sexual-stage gametocyte inhibition occurs at micromolar levels; however, mature gametocyte progression to gamete formation is inhibited at submicromolar concentrations. Parasite reduction ratio analysis confirms a high asexual-stage rate of killing. Both compounds examined displayed oral efficacy in in vivo mouse models of Plasmodium berghei and P. falciparum infection. The discovery of a rapid and broadly acting antimalarial compound class targeting blood stage infection, including transmission stage parasites, and effective against multiple malaria-causing species reveals the diaminoquinazoline scaffold to be a very promising lead for development into greatly needed novel therapies to control malaria.


Assuntos
Antimaláricos/uso terapêutico , Azepinas/uso terapêutico , Histona-Lisina N-Metiltransferase/antagonistas & inibidores , Malária/tratamento farmacológico , Quinazolinas/uso terapêutico , Animais , Antimaláricos/química , Azepinas/química , Feminino , Células Hep G2 , Histona Metiltransferases , Humanos , Malária Falciparum/tratamento farmacológico , Camundongos , Camundongos SCID , Plasmodium berghei/efeitos dos fármacos , Plasmodium berghei/patogenicidade , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/patogenicidade , Quinazolinas/química
6.
Perm J ; 28(3): 84-90, 2024 09 16.
Artigo em Inglês | MEDLINE | ID: mdl-39042384

RESUMO

BACKGROUND: Lupus nephritis (LN) is the most common cause of kidney injury in systemic lupus erythematosus and associated with higher morbidity and mortality. Low medication adherence correlates with adverse clinical outcomes. METHODS: In a large, integrated health system at Kaiser Permanente East Bay Area, the authors identified mycophenolate mofetil (MMF) prescriptions for LN and collected patient demographics, medication adherence, and copay data. They interviewed patients with low medication adherence rates to understand contributing factors, such as side effects, cost, refill processes, and laboratory draws. Adherence was defined as a proportion of days covered at > 80%. The proportion of days covered is the number of days covered by a medication divided by the number of days in a defined period. RESULTS: Between November 30, 2021, and November 30, 2022, the authors identified 36 patients with LN on MMF. Almost a third (11/36) of these patients were nonadherent to medication. More than half (7/11) of these patients agreed to be interviewed. They identified the following causes of medication nonadherence: forgetfulness (57%, or 4/7), incomplete laboratory work (28%, or 2/7), medication cost (14%, or 1/7), and intentionally missed doses (14%, or 1/7). No patients identified medication side effects as a cause. The median 30-day copay for MMF was $4.55, and 28% (2/7) of patients paid $0 for their medications. CONCLUSIONS: In the authors' integrated health system, 69% of their patients with LN on MMF were adherent to their medication regimen. Forgetfulness was a challenge for the nonadherent patients. Kaiser Permanente East Bay Area provides convenient refills and laboratory draws; this likely facilitates medication adherence.


Assuntos
Adesão à Medicação , Ácido Micofenólico , Humanos , Adesão à Medicação/estatística & dados numéricos , Feminino , Masculino , Adulto , Pessoa de Meia-Idade , Ácido Micofenólico/uso terapêutico , Nefrite Lúpica/tratamento farmacológico , Imunossupressores/uso terapêutico , Imunossupressores/administração & dosagem , Entrevistas como Assunto , Lúpus Eritematoso Sistêmico/tratamento farmacológico , Assistência Centrada no Paciente
7.
FASEB J ; 25(9): 3271-8, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21670064

RESUMO

Transient environmental influences, such as perinatal nutritional stress, may induce deleterious metabolic symptoms that last for the entire life of individuals, implying that epigenetic modifications play an important role in this process. We have investigated, in mice, the consequences of maternal undernutrition during gestation and lactation on DNA methylation and expression of the leptin gene, which plays a major regulatory role in coordinating nutritional state with many aspects of mammalian biology. We show that animals born to mothers fed a low-protein-diet (F1-LPD group) have a lower body weight/adiposity and exhibit a higher food intake than animals born to mothers fed a control diet (F1-CD group). These modifications persisted throughout life and were associated with lower levels of leptin mRNA and protein in starved F1-LPD mice, emphasizing that maternal protein-undernutrition affects the balance between food intake and energy expenditure in adults. Moreover, this nutritional stress resulted in the removal of methyls at CpGs located in the promoter of leptin, causing a permanent specific modification in the dynamics of the expression of leptin, which exhibits a stronger induction in the F1-LPD than in F1-CD mice in response to a meal. This study is an example of a molecular rationale linking transient environmental influences to permanent phenotypic consequences.


Assuntos
Dieta , Proteínas Alimentares/farmacologia , Leptina/metabolismo , Síndrome Metabólica/etiologia , Fenômenos Fisiológicos da Nutrição Pré-Natal , Animais , Sequência de Bases , Composição Corporal , Ilhas de CpG , Feminino , Regulação da Expressão Gênica/fisiologia , Humanos , Leptina/genética , Camundongos , Camundongos Endogâmicos BALB C , Gravidez , Regiões Promotoras Genéticas , RNA Mensageiro/genética , RNA Mensageiro/metabolismo
8.
mBio ; 12(2)2021 04 27.
Artigo em Inglês | MEDLINE | ID: mdl-33906926

RESUMO

Posttranscriptional regulation of gene expression is central to the development and replication of the malaria parasite, Plasmodium falciparum, within its human host. The timely coordination of RNA maturation, homeostasis, and protein synthesis relies on the recruitment of specific RNA-binding proteins to their cognate target mRNAs. One possible mediator of such mRNA-protein interactions is the N6-methylation of adenosines (m6A), a prevalent mRNA modification of parasite mRNA transcripts. Here, we used RNA protein pulldowns, RNA modification mass spectrometry, and quantitative proteomics to identify two P. falciparum YTH domain proteins (PfYTH.1 and PfYTH.2) as m6A-binding proteins during parasite blood-stage development. Interaction proteomics revealed that PfYTH.2 associates with the translation machinery, including multiple subunits of the eukaryotic initiation factor 3 (eIF3) and poly(A)-binding proteins. Furthermore, knock sideways of PfYTH.2 coupled with ribosome profiling showed that this m6A reader is essential for parasite survival and is a repressor of mRNA translation. Together, these data reveal an important missing link in the m6A-mediated mechanism controlling mRNA translation in a unicellular eukaryotic pathogen.IMPORTANCE Infection with the unicellular eukaryotic pathogen Plasmodium falciparum causes malaria, a mosquito-borne disease affecting more than 200 million and killing 400,000 people each year. Underlying the asexual replication within human red blood cells is a tight regulatory network of gene expression and protein synthesis. A widespread mechanism of posttranscriptional gene regulation is the chemical modification of adenosines (m6A), through which the fate of individual mRNA transcripts can be changed. Here, we report on the protein machinery that "reads" this modification and "translates" it into a functional outcome. We provide mechanistic insight into one m6A reader protein and show that it interacts with the translational machinery and acts as a repressor of mRNA translation. This m6A-mediated phenotype has not been described in other eukaryotes as yet, and the functional characterization of the m6A interactome will ultimately open new avenues to combat the disease.


Assuntos
Regulação da Expressão Gênica , Plasmodium falciparum/genética , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismo , Adenosina/metabolismo , Eritrócitos/parasitologia , Humanos , Malária Falciparum/parasitologia , Metilação , Plasmodium falciparum/metabolismo , Proteômica , Processamento Pós-Transcricional do RNA , RNA Mensageiro/metabolismo
9.
J Pineal Res ; 48(3): 263-269, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-20210849

RESUMO

The melatonin receptor family is composed of three members, MT(1) and MT(2) receptors that bind melatonin with high affinity and the orphan GPR50 that does not bind melatonin but shares significant sequence homology with the two other subtypes. In the absence of any known ligand for this orphan receptor, little is still known about its function. We recently reported the development of the first anti-GPR50 antibodies that reliably recognized the recombinant human GPR50. We here used these antibodies to study the expression of GPR50 in mouse, rat and human hypothalamus, a region reported to express GPR50 mRNA. GPR50 immunoreactivity (ir) was observed in dorsomedial hypothalamic (DMH) cells co-stained with the neuronal marker HuC/D. GPR50-ir was also observed in cells of the ependymal layer of the third ventricle that co-stained with vimentin. More specifically, its localization in the lower region of the third ventricle and along the long basal processes contacting portal blood vessels in the median eminence (ME) suggested expression of GPR50 in tanycytes. Consistent staining patterns were observed in all three species with two different antibodies. Taken together, our study validates two GPR50-specific antibodies for the use in rodent and human tissue. Evolutionary conserved expression of GPR50 in DMH neurons and tanycytes, together with previously reported expression of the receptor in the pituitary, support the potentially important role of GPR50 in key hypothalamic functions, including regulation of the hypothalamo-pituitary axes.


Assuntos
Hipotálamo/metabolismo , Proteínas do Tecido Nervoso/biossíntese , Receptores Acoplados a Proteínas G/biossíntese , Idoso de 80 Anos ou mais , Animais , Anticorpos/química , Anticorpos/imunologia , Humanos , Hipotálamo/citologia , Imuno-Histoquímica , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Microscopia de Fluorescência , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/imunologia , Ratos , Ratos Sprague-Dawley , Receptores Acoplados a Proteínas G/genética , Receptores Acoplados a Proteínas G/imunologia , Reprodutibilidade dos Testes , Vimentina/metabolismo
10.
Proc Natl Acad Sci U S A ; 104(49): 19476-81, 2007 Dec 04.
Artigo em Inglês | MEDLINE | ID: mdl-18042720

RESUMO

Obesity is a major public health problem and is often associated with type 2 diabetes mellitus, cardiovascular disease, and metabolic syndrome. Leptin is the crucial adipostatic hormone that controls food intake and body weight through the activation of specific leptin receptors (OB-R) in the hypothalamic arcuate nucleus (ARC). However, in most obese patients, high circulating levels of leptin fail to bring about weight loss. The prevention of this "leptin resistance" is a major goal for obesity research. We report here a successful prevention of diet-induced obesity (DIO) by silencing a negative regulator of OB-R function, the OB-R gene-related protein (OB-RGRP), whose transcript is genetically linked to the OB-R transcript. We provide in vitro evidence that OB-RGRP controls OB-R function by negatively regulating its cell surface expression. In the DIO mouse model, obesity was prevented by silencing OB-RGRP through stereotactic injection of a lentiviral vector encoding a shRNA directed against OB-RGRP in the ARC. This work demonstrates that OB-RGRP is a potential target for obesity treatment. Indeed, regulators of the receptor could be more appropriate targets than the receptor itself. This finding could serve as the basis for an approach to identifying potential new therapeutic targets for a variety of diseases, including obesity.


Assuntos
Núcleo Arqueado do Hipotálamo/metabolismo , Proteínas de Transporte/antagonistas & inibidores , Leptina/metabolismo , Obesidade/prevenção & controle , Receptores para Leptina/metabolismo , Animais , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Dieta , Gorduras na Dieta/administração & dosagem , Genes Reporter , Proteínas de Fluorescência Verde/análise , Proteínas de Fluorescência Verde/genética , Hipotálamo/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular , Lentivirus/genética , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Obesidade/metabolismo , Oligonucleotídeos Antissenso/genética , Receptores para Leptina/antagonistas & inibidores , Receptores para Leptina/genética , Transdução de Sinais
11.
Comp Med ; 70(2): 176-182, 2020 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-32160941

RESUMO

Endovascular microcatheter-based intraarterial (ophthalmic artery) chemotherapy is becoming widely used for the clinical treatment of intraocular retinoblastoma due to its apparent increased efficacy compared with traditional intravenous chemotherapy; however local ocular complications are not uncommon. Carboplatin is a chemotherapeutic agent used in both intravenous and intraarterial chemotherapy. We used rabbits to assess pharmacokinetics and ocular and systemic toxicity after intraarterial carboplatin infusion. Subsequent to unilateral intraarterial administration of carboplatin, severe unilateral or bilateral periocular edema occurred in 6 adult male New Zealand white rabbits. Time to onset varied from less than 4 h after administration (n = 3, 50 mg) to approximately 24 h afterward (n = 3, 25 mg). After becoming symptomatic, 5 of the 6 animals were promptly euthanized, and the remaining animal (25 mg treatment) was medically managed for 4 d before being euthanized due to intractable edema-related lagophthalmos. Globes and orbits from all 6 euthanized rabbits were harvested en bloc; whole-mount sections were prepared for histologic evaluation, which revealed drug-induced vasogenic edema in confined spaces as the main underlying pathogenesis. Transient and self-limiting periocular edema is a common side effect of intraarterial chemotherapy but is thought to occur predominantly with melphalan monotherapy or combination therapy using melphalan, carboplatin, and topotecan. The severity of this adverse consequence in rabbits was unexpected, and its use in the study was subsequently discontinued. Although the definitive cause for this vasotoxicity and striking clinical presentation is unknown, we suspect species-specific anatomic features and sensitivity might have contributed to amplified complications after intraarterial carboplatin chemotherapy of the eye. Due to the adverse effects of intraarterial carboplatin chemotherapy that we observed in 2 experimental cohorts of rabbits, we recommend caution regarding its use in this species.


Assuntos
Antineoplásicos/efeitos adversos , Carboplatina/efeitos adversos , Edema/induzido quimicamente , Oftalmopatias/induzido quimicamente , Retinoblastoma/tratamento farmacológico , Animais , Antineoplásicos/administração & dosagem , Carboplatina/administração & dosagem , Modelos Animais de Doenças , Edema/patologia , Oftalmopatias/patologia , Infusões Intra-Arteriais/efeitos adversos , Coelhos
12.
J Am Assoc Lab Anim Sci ; 59(2): 176-185, 2020 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-32005295

RESUMO

New Zealand white rabbits (Oryctolagus cuniculus) are an established in vivo model for the study of structural and functional consequences of vocal-fold vibration. Research design requires invasive laryngotracheal procedures, and the presence of laryngospasms or pain responses (or both) hinder phonation-related data collection. Published anesthesia regimens report respiratory depression and muscle tone changes and have been unsuccessful in mitigating autonomic laryngeal responses in our protocol. Infusion of ketamine hydrochloride and dexmedetomidine hydrochloride in pediatric medicine provides effective analgesia and sedation for laryngotracheal procedures including intubation and bronchoscopy; however, data evaluating the use of ketamine-dexmedetomidine infusion in rabbits are unavailable. This study reports a new infusion regimen, which was used in 58 male New Zealand white rabbits that underwent a nonsurvival laryngotracheal procedure to induce phonotraumatic vocal-fold injury. Animals were sedated by using ketamine hydrochloride (20 mg/kg IM) and dexmedetomidine (0.125 mg/kg IM). Maintenance anesthesia was provided by using continuous rate intravenous infusion of ketamine hydrochloride (343 µg/kg/min) and dexmedetomidine (1.60 µg/kg/min). A stable plane of anesthesia with no autonomic laryngeal response (laryngospasm) was achieved in 32 of the 58 rabbits (55%). Laryngospasms occurred in 25 of 58 animals (43%) and were controlled in 20 cases (80%) by providing 0.33 mL 2% topical lidocaine, incremental increase in infusion rate, or both. Continuous rate infusion of ketamine hydrochloride-dexmedetomidine with prophylactic topical lidocaine provides a predictable and adjustable surgical plane of anesthesia, with minimal confounding respiratory and autonomic laryngeal responses, during extended-duration laryngotracheal surgery in rabbits. This regimen should be considered as an alternative to injection maintenance for prolonged, invasive procedures.


Assuntos
Anestesia , Dexmedetomidina , Ketamina , Coelhos , Animais , Feminino , Masculino , Coelhos/cirurgia , Analgesia , Anestesia/veterinária , Dexmedetomidina/administração & dosagem , Dexmedetomidina/farmacologia , Esquema de Medicação , Quimioterapia Combinada , Hipnóticos e Sedativos/administração & dosagem , Hipnóticos e Sedativos/farmacologia , Ketamina/administração & dosagem , Ketamina/farmacologia , Lidocaína/farmacologia , Manutenção
13.
Cell Rep ; 22(11): 2951-2963, 2018 03 13.
Artigo em Inglês | MEDLINE | ID: mdl-29539423

RESUMO

Heterochromatin plays a central role in the process of immune evasion, pathogenesis, and transmission of the malaria parasite Plasmodium falciparum during blood stage infection. Here, we use ChIP sequencing to demonstrate that sporozoites from mosquito salivary glands expand heterochromatin at subtelomeric regions to silence blood-stage-specific genes. Our data also revealed that heterochromatin enrichment is predictive of the transcription status of clonally variant genes members that mediate cytoadhesion in blood stage parasites. A specific member (here called NF54varsporo) of the var gene family remains euchromatic, and the resultant PfEMP1 (NF54_SpzPfEMP1) is expressed at the sporozoite surface. NF54_SpzPfEMP1-specific antibodies efficiently block hepatocyte infection in a strain-specific manner. Furthermore, human volunteers immunized with infective sporozoites developed antibodies against NF54_SpzPfEMP1. Overall, we show that the epigenetic signature of var genes is reset in mosquito stages. Moreover, the identification of a strain-specific sporozoite PfEMP1 is highly relevant for vaccine design based on sporozoites.


Assuntos
Hepatócitos/imunologia , Proteínas de Protozoários/metabolismo , Esporozoítos/imunologia , Animais
14.
J Am Assoc Lab Anim Sci ; 56(6): 779-785, 2017 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-29256373

RESUMO

Due to potential adverse effects on animal wellbeing, the use of nonpharmaceutical-grade substances in animal research must be scientifically justified in cases where a pharmaceutical-grade version of the substance exists. This requirement applies to all substances, including vehicles used to solubilize experimental drugs. To date, no studies have evaluated the direct effect of the pharmaceutical classification of a compound on animal wellbeing. In this study, we evaluated intraperitoneal administration of pharmaceutical-grade corn oil, nonpharmaceutical-grade corn oil, and saline in female C57BL/6J mice. Compounds were administered every 48 h for a total of 4 injections. Mice were evaluated clinically by using body weight, body condition score, visual assessment score, CBC, and serum chemistries. Animals were euthanized at 24 h and 14 d after the final injection. Inflammation of the peritoneal wall and mesenteric fat was assessed microscopically by using a semiquantitative scoring system. Saline-dosed groups had lower pathology scores at both time points. At day 21, pharmaceutical-grade corn oil had a significantly higher pathology score compared with nonpharmaceutical-grade corn oil. No other significant differences between the corn oil groups were observed. The use of nonpharmaceutical grade corn oil did not result in adverse clinical consequences and is presumed safe to use for intraperitoneal injection in mice. Differences in inflammation between the 2 groups suggest that the use of either pharmaceutical-grade or nonpharmaceutical-grade corn oil should be consistent within a study.


Assuntos
Bem-Estar do Animal , Óleo de Milho/administração & dosagem , Óleo de Milho/efeitos adversos , Portadores de Fármacos/administração & dosagem , Portadores de Fármacos/efeitos adversos , Camundongos/fisiologia , Preparações Farmacêuticas/administração & dosagem , Animais , Peso Corporal/efeitos dos fármacos , Óleo de Milho/química , Feminino , Injeções Intraperitoneais , Masculino , Camundongos Endogâmicos C57BL
15.
Medchemcomm ; 8(5): 1069-1092, 2017 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-29308121

RESUMO

Plasmodium falciparum HKMTs (PfHKMTs) play a key role in controlling Plasmodium gene expression and represent exciting new anti-malarial epigenetic targets. Using an inhibitor series derived from the diaminoquinazoline HKMT inhibitory chemotype, we have previously identified compounds with highly promising antimalarial activity, including irreversible asexual cycle blood stage-independent cytotoxic activity at nM concentrations, oral efficacy in in vivo models of disease, and the unprecedented ability to reactivate dormant liver stage parasites (hypnozoites). However, future development of this series will need to address host versus parasite selectivity, where inhibitory activity against human G9a is removed from the lead compounds, while maintaining potent anti-Plasmodium activity. Herein, we report an extensive study of the SAR of this series against both G9a and P. falciparum. We have identified key SAR features which demonstrate that high parasite vs. G9a selectivity can be achieved by selecting appropriate substituents at position 2, 4 and 7 of the quinazoline ring. We have also, in turn, discovered that potent G9a inhibitors can be identified by employing a 6-carbon 'Nle mimic' at position 7. Together, this data suggests that while broadly similar, the G9a and potential PfHKMT target(s) binding pockets and/or binding modes of the diaminoquinazoline analogues exhibit clear and exploitable differences. Based on this, we believe this scaffold to have clear potential for development into a novel anti-malarial therapeutic.

16.
Mol Metab ; 6(1): 159-172, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-28123946

RESUMO

The hypothalamic arcuate nucleus (ARC) is a major integration center for energy and glucose homeostasis that responds to leptin. Resistance to leptin in the ARC is an important component of the development of obesity and type 2 diabetes. Recently, we showed that Endospanin1 (Endo1) is a negative regulator of the leptin receptor (OBR) that interacts with OBR and retains the receptor inside the cell, leading to a decreased activation of the anorectic STAT3 pathway. Endo1 is up-regulated in the ARC of high fat diet (HFD)-fed mice, and its silencing in the ARC of lean and obese mice prevents and reverses the development of obesity. OBJECTIVE: Herein we investigated whether decreased Endo1 expression in the hypothalamic ARC, associated with reduced obesity, could also ameliorate glucose homeostasis accordingly. METHODS: We studied glucose homeostasis in lean or obese mice silenced for Endo1 in the ARC via stereotactic injection of shRNA-expressing lentiviral vectors. RESULTS: We observed that despite being leaner, Endo1-silenced mice showed impaired glucose homeostasis on HFD. Mechanistically, we show that Endo1 interacts with p85, the regulatory subunit of PI3K, and mediates leptin-induced PI3K activation. CONCLUSIONS: Our results thus define Endo1 as an important hypothalamic integrator of leptin signaling, and its silencing differentially regulates the OBR-dependent functions.


Assuntos
Proteínas de Transporte/metabolismo , Obesidade/metabolismo , Receptores para Leptina/metabolismo , Animais , Núcleo Arqueado do Hipotálamo/metabolismo , Peso Corporal/fisiologia , Proteínas de Transporte/fisiologia , Diabetes Mellitus Tipo 2/metabolismo , Dieta Hiperlipídica/efeitos adversos , Glucose/metabolismo , Homeostase/efeitos dos fármacos , Hipotálamo/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular , Leptina/metabolismo , Leptina/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Obesos , Receptores para Leptina/fisiologia , Fator de Transcrição STAT3/efeitos dos fármacos , Fator de Transcrição STAT3/metabolismo , Transdução de Sinais/efeitos dos fármacos
17.
Sci Rep ; 6: 21802, 2016 Feb 23.
Artigo em Inglês | MEDLINE | ID: mdl-26902486

RESUMO

Epigenetic control via reversible histone methylation regulates transcriptional activation throughout the malaria parasite genome, controls the repression of multi-copy virulence gene families and determines sexual stage commitment. Plasmodium falciparum encodes ten predicted SET domain-containing protein methyltransferases, six of which have been shown to be refractory to knock-out in blood stage parasites. We have expressed and purified the first recombinant malaria methyltransferase in sufficient quantities to perform a full enzymatic characterization and reveal the ill-defined PfSET7 is an AdoMet-dependent histone H3 lysine methyltransferase with highest activity towards lysines 4 and 9. Steady-state kinetics of the PfSET7 enzyme are similar to previously characterized histone methyltransferase enzymes from other organisms, however, PfSET7 displays specific protein substrate preference towards nucleosomes with pre-existing histone H3 lysine 14 acetylation. Interestingly, PfSET7 localizes to distinct cytoplasmic foci adjacent to the nucleus in erythrocytic and liver stage parasites, and throughout the cytoplasm in salivary gland sporozoites. Characterized recombinant PfSET7 now allows for target based inhibitor discovery. Specific PfSET7 inhibitors can aid in further investigating the biological role of this specific methyltransferase in transmission, hepatic and blood stage parasites, and may ultimately lead to the development of suitable antimalarial drug candidates against this novel class of essential parasite enzymes.


Assuntos
Histona-Lisina N-Metiltransferase/metabolismo , Histonas/metabolismo , Plasmodium falciparum/enzimologia , Proteínas de Protozoários/metabolismo , Esporozoítos/enzimologia , Trofozoítos/enzimologia , Sequência de Aminoácidos , Animais , Anopheles/parasitologia , Baculoviridae/genética , Baculoviridae/metabolismo , Clonagem Molecular , Epigênese Genética , Eritrócitos/parasitologia , Eritrócitos/ultraestrutura , Expressão Gênica , Histona-Lisina N-Metiltransferase/genética , Histonas/genética , Humanos , Cinética , Fígado/citologia , Fígado/parasitologia , Mutação , Plasmodium falciparum/genética , Plasmodium falciparum/ultraestrutura , Proteínas de Protozoários/genética , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Glândulas Salivares/parasitologia , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Células Sf9 , Spodoptera , Esporozoítos/ultraestrutura , Especificidade por Substrato , Trofozoítos/ultraestrutura
18.
Tissue Eng ; 11(9-10): 1436-48, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-16259599

RESUMO

The objective of this study was to investigate the histology of tissue formed when fetal rat lung cells were grown in a collagen-glycosaminoglycan (GAG) tissue-engineering scaffold. The goal was the formation of lung histotypic structures in the tissue-engineering scaffolds in vitro. Achieving this goal would facilitate future investigations of the effects of selected scaffold design parameters on processes that may underlie aspects of lung regeneration in vivo. Lung cells were obtained from Sprague-Dawley rats after 16 and 19 days of gestation. These dissociated cells were seeded into type I collagen-chondroitin 6-sulfate matrices, 8 mm in diameter by 2 mm in thickness, cross-linked and sterilized by dehydrothermal treatment. Approximately 28 million cells were seeded into each spongelike sample. Histological and immunohistochemical studies were performed at termination periods of 2 days and 1, 2, and 3 weeks. The enzymatically dissociated 19-day gestation fetal rat lung cells formed and maintained alveolar-like structures, 50-60 microm in diameter, in the collagen- GAG scaffold. A novel finding was that all of the cell-seeded scaffolds underwent cell-mediated contraction that appeared to be associated with the finding by immunohistochemistry of expression of alpha-smooth muscle actin in some cells. These results demonstrate the capability of dissociated lung cells to form lung histotypic structures in collagen-GAG tissue-engineering scaffolds in vitro. This culture system may be of value in facilitating exploration of strategies for preparing such scaffolds for the regeneration of lung tissue in vivo.


Assuntos
Colágeno Tipo I/metabolismo , Glicosaminoglicanos/metabolismo , Pulmão/citologia , Pulmão/embriologia , Engenharia Tecidual/métodos , Actinas/análise , Animais , Anticorpos Monoclonais/metabolismo , Carbodi-Imidas/química , Bovinos , Células Cultivadas , Sulfatos de Condroitina/química , Sulfatos de Condroitina/metabolismo , Colágeno Tipo I/química , Dessecação , Elastina/metabolismo , Matriz Extracelular/química , Matriz Extracelular/metabolismo , Glicosaminoglicanos/química , Técnicas Histológicas , Temperatura Alta , Imuno-Histoquímica , Porosidade , Ratos , Ratos Sprague-Dawley , Tendões/química , Fatores de Tempo
19.
Neuroreport ; 16(8): 849-52, 2005 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-15891583

RESUMO

Lateralized responses for visually elicited feeding behaviour have been reported in toads and birds but not in the phylogenetically intermediate class of vertebrates, the reptiles. Here we examined small social groups of ornate dragon lizards Ctenophorus ornatus (family Agamidae) and provide the first report in reptiles of right eye lateralization (left brain hemisphere) for predatory responses to prey. However, right eye lateralization was not evident initially but became stronger with time supporting a shift to right eye lateralization as the prey became increasingly familiar. The study is in agreement with recent findings in toads, adding credence to the hypothesis that lateralization originated in an early ancestor and highlighting the supposition that the strength and direction of lateralization is dependent on experience.


Assuntos
Lateralidade Funcional/fisiologia , Lagartos/fisiologia , Comportamento Predatório/fisiologia , Percepção Visual/fisiologia , Animais , Comportamento Animal , Olho/inervação , Iguanas , Estimulação Luminosa/métodos
20.
F1000Prime Rep ; 6: 78, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25343035

RESUMO

Ankylosing spondylitis (AS) is a chronic inflammatory disease with prominent involvement of the spine and sacroiliac joints which frequently leads to significant spine deformity and disability. The development of effective therapies for AS, particularly with anti-tumor necrosis factor agents, has resulted in improved symptoms and functions for many patients, and clinical research increasingly suggests that effective therapy can also prevent destruction in the spine and other structures. Recent focus of disease classification in AS has emphasized that many individuals with features of inflammatory back pain but no visible changes on plain x-rays have active inflammatory disease when imaged with magnetic resonance imaging (MRI). Recent studies indicate that individuals with "non-radiographic" spondylitis can also respond to anti-inflammatory therapies. Several new agents are also showing promise for treatment of AS. These developments represent a significant advance in the management of this debilitating condition.

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