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1.
Cell ; 146(1): 134-47, 2011 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-21729785

RESUMO

In eukaryotic cells, the ribosome-Sec61 translocon complex (RTC) establishes membrane protein topology by cotranslationally partitioning nascent polypeptides into the cytosol, ER lumen, and lipid bilayer. Using photocrosslinking, collisional quenching, cysteine accessibility, and protease protection, we show that a canonical type II signal anchor (SA) acquires its topology through four tightly coupled and mechanistically distinct steps: (1) head-first insertion into Sec61α, (2) nascent chain accumulation within the RTC, (3) inversion from type I to type II topology, and (4) stable translocation of C-terminal flanking residues. Progression through each stage is induced by incremental increases in chain length and involves abrupt changes in the molecular environment of the SA. Importantly, type II SA inversion deviates from a type I SA at an unstable intermediate whose topology is controlled by dynamic interactions between the ribosome and translocon. Thus, the RTC coordinates SA topogenesis within a protected environment via sequential energetic transitions of the TM segment.


Assuntos
Proteínas de Membrana/metabolismo , Biossíntese de Proteínas , Ribossomos/metabolismo , Animais , Sistema Livre de Células , Cães , Retículo Endoplasmático/metabolismo , Microssomos/metabolismo , Sinais Direcionadores de Proteínas , Coelhos , Canais de Translocação SEC
2.
J Cell Physiol ; 239(1): 135-151, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37942831

RESUMO

In tandem with the expanding obesity pandemic, the prevalence of metabolic dysfunction associated steatohepatitis (MASH, formerly known as NASH)- driven hepatocellular carcinoma (HCC) is predicted to rise globally, creating a significant need for therapeutic interventions. We previously identified the upregulation of apoptosis antagonizing transcription factor (AATF), which is implicated in facilitating the progression from MASH to HCC. The objective of this study was to examine whether the intervention of curcumin could alleviate AATF-mediated MASH, inhibit tumor growth, and elucidate the underlying mechanism. A preclinical murine model mimicking human MASH-HCC was employed, subjecting mice to either a chow diet normal water (CDNW) or western diet sugar water (WDSW) along with very low dose of carbon tetrachloride (CCl4 - 0.2 µL/g, weekly). Mice receiving curcumin (CUR) alongside WDSW/CCl4 exhibited significant improvements, including reduced liver enzymes, dyslipidemia, steatosis, inflammation, and hepatocellular ballooning. Curcumin treatment also suppressed hepatic expression of inflammatory, fibrogenic, and oncogenic markers. Of note, there was a significant reduction in the expression of AATF upon curcumin treatment in WDSW/CCl4 mice and human HCC cells. In contrast, curcumin upregulated Kruppel-like factor 4 (KLF4) in MASH liver and HCC cells, which is known to downregulate sp1 (specificity protein-1) expression. Thus, curcumin treatment effectively inhibited the progression of MASH to HCC by downregulating the expression of AATF via the KLF4-Sp1 signaling pathway. These preclinical findings establish a novel molecular connection between curcumin and AATF in reducing hepatocarcinogenesis, and provide a strong rationale for the development of curcumin as a viable treatment for MASH-HCC in humans.


Assuntos
Carcinoma Hepatocelular , Curcumina , Fígado Gorduroso , Neoplasias Hepáticas , Hepatopatia Gordurosa não Alcoólica , Animais , Humanos , Camundongos , Apoptose , Proteínas Reguladoras de Apoptose , Carcinoma Hepatocelular/patologia , Curcumina/farmacologia , Curcumina/uso terapêutico , Fígado Gorduroso/patologia , Inflamação/tratamento farmacológico , Inflamação/patologia , Neoplasias Hepáticas/patologia , Hepatopatia Gordurosa não Alcoólica/tratamento farmacológico , Hepatopatia Gordurosa não Alcoólica/metabolismo , Proteínas Repressoras , Fatores de Transcrição
3.
Development ; 148(16)2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34345920

RESUMO

The melastatin subfamily of the transient receptor potential channels (TRPM) are regulators of pancreatic ß-cell function. TRPM7 is the most abundant islet TRPM channel; however, the role of TRPM7 in ß-cell function has not been determined. Here, we used various spatiotemporal transgenic mouse models to investigate how TRPM7 knockout influences pancreatic endocrine development, proliferation and function. Ablation of TRPM7 within pancreatic progenitors reduced pancreatic size, and α-cell and ß-cell mass. This resulted in modestly impaired glucose tolerance. However, TRPM7 ablation following endocrine specification or in adult mice did not impact endocrine expansion or glucose tolerance. As TRPM7 regulates cell proliferation, we assessed how TRPM7 influences ß-cell hyperplasia under insulin-resistant conditions. ß-Cell proliferation induced by high-fat diet was significantly decreased in TRPM7-deficient ß-cells. The endocrine roles of TRPM7 may be influenced by cation flux through the channel, and indeed we found that TRPM7 ablation altered ß-cell Mg2+ and reduced the magnitude of elevation in ß-cell Mg2+ during proliferation. Together, these findings revealed that TRPM7 controls pancreatic development and ß-cell proliferation, which is likely due to regulation of Mg2+ homeostasis.


Assuntos
Proliferação de Células/genética , Dieta Hiperlipídica , Secreção de Insulina/genética , Células Secretoras de Insulina/metabolismo , Insulina/metabolismo , Pâncreas/crescimento & desenvolvimento , Pâncreas/metabolismo , Canais de Cátion TRPM/metabolismo , Animais , Células Cultivadas , Técnicas de Inativação de Genes , Intolerância à Glucose/genética , Homeostase/genética , Magnésio/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Canais de Cátion TRPM/genética
4.
Nano Lett ; 23(20): 9508-9514, 2023 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-37844301

RESUMO

Bilayer graphene (BLG) was recently shown to host a band-inverted phase with unconventional topology emerging from the Ising-type spin-orbit interaction (SOI) induced by the proximity of transition metal dichalcogenides with large intrinsic SOI. Here, we report the stabilization of this band-inverted phase in BLG symmetrically encapsulated in tungsten diselenide (WSe2) via hydrostatic pressure. Our observations from low temperature transport measurements are consistent with a single particle model with induced Ising SOI of opposite sign on the two graphene layers. To confirm the strengthening of the inverted phase, we present thermal activation measurements and show that the SOI-induced band gap increases by more than 100% due to the applied pressure. Finally, the investigation of Landau level spectra reveals the dependence of the level-crossings on the applied magnetic field, which further confirms the enhancement of SOI with pressure.

5.
Microvasc Res ; 145: 104454, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36347299

RESUMO

OBJECTIVE: Subclinical life style disease can cause endothelial dysfunction associated with perfusion abnormalities and reduced vascular compliance. Subclinical elevated beta type natriuretic peptide (BNP) has been associated with altered fluid shift from extra to intracellular space during acute hypoxia. Therefore we measured vascular response and BNP levels during acute hypoxia to study endothelial functions among healthy individuals. METHODS: Individuals were exposed to acute normobaric hypoxia of FiO2 = 0.15 for one hour in supine position and their pulmonary and systemic vascular response to hypoxia was compared. Individuals were divided into two groups based on either no response (Group 1) or rise in systolic pulmonary artery pressure to hypoxia (Group 2) and their BNP levels were compared. RESULTS: BNP was raised after hypoxia exposure in group 2 only from 18.52 ± 7 to 21.56 ± 10.82 picogram/ml, p < 0.05. Group 2 also showed an increase in mean arterial pressure and no fall in total body water in response to acute hypoxia indicating decreased endothelial function compared to Group 1. CONCLUSION: Rise in pulmonary artery pressure and BNP level in response to acute normobaric hypoxia indicates reduced endothelial function and can be used to screen subclinical lifestyle disease among healthy population.


Assuntos
Hipóxia , Peptídeo Natriurético Encefálico , Humanos , Hipóxia/diagnóstico , Pulmão/irrigação sanguínea , Vasodilatadores , Estilo de Vida , Artéria Pulmonar
6.
Dig Dis Sci ; 68(2): 571-579, 2023 02.
Artigo em Inglês | MEDLINE | ID: mdl-36040554

RESUMO

BACKGROUND: Microscopic colitis is a chronic inflammatory disease that most commonly affects post-menopausal women. Exogenous hormone use has recently been linked with increased risk of microscopic colitis. Yet, it is unclear whether levels of endogenous sex hormones are also associated with risk of microscopic colitis. AIM: To evaluate the association between prediagnostic plasma androgens and subsequent risk of microscopic colitis. METHODS: We conducted a case-control study nested within prospective cohort studies of the Nurses' Health Study (NHS) and NHSII. Cases of microscopic colitis were each matched to two controls according to age, cohort, menopause status, fasting status, and season of plasma collection. Prediagnosis plasma levels of androgens including dehydroepiandrosterone sulfate, testosterone, and sex hormone-binding globulin were measured. We examined the association of each analyte with risk of microscopic colitis using conditional logistic regression models. RESULTS: Our study included 96 cases of microscopic colitis matched to 190 controls. Plasma levels of testosterone were not associated with risk of microscopic colitis (Ptrend = 0.70). Compared to participants in the lowest quartile of plasma testosterone levels, the aOR of microscopic colitis for women in the highest quartile was 0.88, 95% CI 0.45-1.71. Similarly, we did not observe an association between dehydroepiandrosterone sulfate and sex hormone-binding globulin and risk of microscopic colitis (all Ptrend > 0.52). CONCLUSION: Among women, prediagnostic circulating levels of testosterone, dehydroepiandrosterone sulfate, and sex hormone-binding globulin are not associated with risk of microscopic colitis.


Assuntos
Androgênios , Colite Microscópica , Feminino , Humanos , Globulina de Ligação a Hormônio Sexual , Sulfato de Desidroepiandrosterona , Estudos de Casos e Controles , Estudos Prospectivos , Fatores de Risco , Testosterona , Estradiol
7.
Mol Cell ; 58(2): 269-83, 2015 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-25801167

RESUMO

The ER Sec61 translocon is a large macromolecular machine responsible for partitioning secretory and membrane polypeptides into the lumen, cytosol, and lipid bilayer. Because the Sec61 protein-conducting channel has been isolated in multiple membrane-derived complexes, we determined how the nascent polypeptide modulates translocon component associations during defined cotranslational translocation events. The model substrate preprolactin (pPL) was isolated principally with Sec61αßγ upon membrane targeting, whereas higher-order complexes containing OST, TRAP, and TRAM were stabilized following substrate translocation. Blocking pPL translocation by passenger domain folding favored stabilization of an alternate complex that contained Sec61, Sec62, and Sec63. Moreover, Sec62/63 stabilization within the translocon occurred for native endogenous substrates, such as the prion protein, and correlated with a delay in translocation initiation. These data show that cotranslational translocon contacts are ultimately controlled by the engaged nascent chain and the resultant substrate-driven translocation events.


Assuntos
Retículo Endoplasmático/enzimologia , Mamíferos/metabolismo , Proteínas de Membrana/química , Proteínas de Membrana/metabolismo , Animais , Retículo Endoplasmático/química , Estabilidade Enzimática , Príons/metabolismo , Prolactina/metabolismo , Precursores de Proteínas/metabolismo , Transporte Proteico , Especificidade por Substrato
8.
Alcohol Alcohol ; 58(5): 472-477, 2023 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-37565935

RESUMO

BACKGROUND: Therapies to prevent alcohol-associated liver disease (ALD) in high-risk patients are needed. AIMS: In this retrospective association study, we examined whether patients with alcohol use disorder (AUD) who reported greater exercise were less likely to develop liver disease. METHODS: In this retrospective cohort study, we used the Mass General Brigham Biobank to investigate the impact of both moderate-high and light-intensity exercise on the development of ALD in patients with AUD, using clinician-provided diagnostic International Classification of Diseases 10 codes. Exercise was evaluated using a questionnaire completed after an AUD diagnosis, and before evidence of liver disease. Cox regressions were used to generate hazard ratios (HRs) for the development of ALD. RESULTS: 1987 patients met inclusion criteria. These patients were followed for an average of 10.7 years. In multivariable analyses, we found that patients that reported at least 2.5 h of moderate-high intensity exercise/week (confidence interval recommendation for exercise) were less likely to develop ALD compared to patients that did not exercise (HR: 0.26, 95%CI: 0.085-0.64, P = 0.007). Indeed, each hour of moderate-high intensity exercise was associated with progressively decreasing odds of developing ALD (HR: 0.76, 95%CI: 0.58-0.91, P = 0.02). Conversely, patients who did not engage in any moderate-high intensity exercise were more likely to develop ALD (HR: 2.76, 95%CI: 1.44-5.40, P = 0.003). CONCLUSIONS: In our cohort, patients with AUD who reported moderate-high intensity exercise showed a lower association with incidence of ALD development than patients who did not exercise.


Assuntos
Alcoolismo , Hepatopatias Alcoólicas , Transplante de Fígado , Humanos , Estudos Retrospectivos , Hepatopatias Alcoólicas/complicações , Consumo de Bebidas Alcoólicas/efeitos adversos , Alcoolismo/epidemiologia , Alcoolismo/complicações
9.
Nano Lett ; 22(21): 8601-8607, 2022 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-36279222

RESUMO

Tunneling spectroscopy measurements are often used to probe the energy spectrum of Andreev bound states (ABSs) in semiconductor-superconductor hybrids. Recently, this spectroscopy technique has been incorporated into planar Josephson junctions (JJs) formed in two-dimensional electron gases, a potential platform to engineer phase-controlled topological superconductivity. Here, we perform ABS spectroscopy at the two ends of planar JJs and study the effects of the magnetic vector potential on the ABS spectrum. We show that the local superconducting phase difference arising from the vector potential is equal in magnitude and opposite in sign at the two ends, in agreement with a model that assumes localized ABSs near the tunnel barriers. Complemented with microscopic simulations, our experiments demonstrate that the local phase difference can be used to estimate the relative position of localized ABSs separated by a few hundred nanometers.

10.
J Assoc Physicians India ; 71(6): 11-12, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-37355845

RESUMO

BACKGROUND: Cough has a prevalence of 9.6% globally and 5-10% in India. Though it is a reflex action, it affects an individual's quality of life (QoL) when uncontrolled. There was a need to create an integrated guidance document on managing cough focused on primary care physicians in the Indian setting. This consensus intends to bridge this gap by providing clinical recommendations to diagnose and manage cough in primary healthcare in India. MATERIALS AND METHODS: The modified Delphi method was used to arrive at a consensus on clinical statements. The panel comprised 10 experts, including pulmonologists, otolaryngologists, a pediatrician, and a general physician. The statements were discussed under the following domains: definition, etiology, diagnosis, and treatment. RESULTS: A total of 109 clinical statements were framed, with 75 reaching consensus, 13 reaching near consensus, and 21 reaching no consensus. The experts recommended empiric use of nonopioid antitussive agents for symptomatic relief of acute dry cough. The use of oral antihistamines, oral decongestants, or mucoactive agents as a part of fixed-dose combinations (FDCs) in cough associated with rhinitis or upper airway cough syndrome (UACS) can be considered for symptomatic relief. Maintaining good hydration is important to manage a productive cough. Codeine-based preparations are to be considered as a last resort in patients with an unexplained chronic cough when other treatments have failed. Additionally, insights were captured on red flag signs, nonpharmacologic therapy, special populations, and referral to higher centers. Experts have also proposed a management algorithm with an integrated care pathway approach for acute, subacute, and chronic coughs. CONCLUSION: The present consensus fills the existing need and may guide the physician to successfully diagnose and manage cough in the primary healthcare setting in India.


Assuntos
Tosse , Qualidade de Vida , Humanos , Tosse/diagnóstico , Tosse/etiologia , Tosse/terapia , Antagonistas dos Receptores Histamínicos/uso terapêutico , Doença Crônica , Atenção Primária à Saúde
11.
J Biol Chem ; 296: 100632, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33865855

RESUMO

Nonshivering thermogenesis is essential for mammals to maintain body temperature. According to the canonical view, temperature is sensed by cutaneous thermoreceptors and nerve impulses transmitted to the hypothalamus, which generates sympathetic signals to ß-adrenergic receptors in brown adipocytes. The energy for heat generation is primarily provided by the oxidation of fatty acids derived from triglyceride hydrolysis and cellular uptake. Fatty acids also activate the uncoupling protein, UCP1, which creates a proton leak that uncouples mitochondrial oxidative phosphorylation from ATP production, resulting in energy dissipation as heat. Recent evidence supports the idea that in response to mild cold, ß-adrenergic signals stimulate not only lipolysis and fatty acid oxidation, but also act through the mTORC2-Akt signaling module to stimulate de novo lipogenesis. This opposing anabolic effect is thought to maintain lipid fuel stores during increased catabolism. We show here, using brown fat-specific Gs-alpha knockout mice and cultured adipocytes that, unlike mild cold, severe cold directly cools brown fat and bypasses ß-adrenergic signaling to inhibit mTORC2. This cell-autonomous effect both inhibits lipogenesis and augments UCP1 expression to enhance thermogenesis. These findings suggest a novel mechanism for overriding ß-adrenergic-stimulated anabolic activities while augmenting catabolic activities to resolve the homeostatic crisis presented by severe cold.


Assuntos
Tecido Adiposo Marrom/metabolismo , Cromograninas/fisiologia , Temperatura Baixa , Subunidades alfa Gs de Proteínas de Ligação ao GTP/fisiologia , Alvo Mecanístico do Complexo 2 de Rapamicina/metabolismo , Termogênese , Tecido Adiposo Marrom/citologia , Animais , Lipogênese , Masculino , Alvo Mecanístico do Complexo 2 de Rapamicina/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptores Adrenérgicos beta/genética , Receptores Adrenérgicos beta/metabolismo , Transdução de Sinais , Proteína Desacopladora 1/genética , Proteína Desacopladora 1/metabolismo
12.
Am J Physiol Renal Physiol ; 323(2): F156-F170, 2022 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-35695380

RESUMO

The lysosomal storage disease cystinosis is caused by mutations in CTNS, encoding the cystine transporter cystinosin, and in its severest form leads to proximal tubule dysfunction followed by kidney failure. Patients receive the drug-based therapy cysteamine from diagnosis. However, despite long-term treatment, cysteamine only slows the progression of end-stage renal disease. Preclinical testing in cystinotic rodents is required to evaluate new therapies; however, the current models are suboptimal. To solve this problem, we generated a new cystinotic rat model using CRISPR/Cas9-mediated gene editing to disrupt exon 3 of Ctns and measured various parameters over a 12-mo time course. Ctns-/- rats display hallmarks of cystinosis by 3-6 mo of age, as demonstrated by a failure to thrive, excessive thirst and urination, cystine accumulation in tissues, corneal cystine crystals, loss of LDL receptor-related protein 2 in proximal tubules, and immune cell infiltration. High levels of glucose, calcium, albumin, and protein were excreted at 6 mo of age, consistent with the onset of Fanconi syndrome, with a progressive diminution of urine urea and creatinine from 9 mo of age, indicative of chronic kidney disease. Kidney histology and immunohistochemistry showed proximal tubule atrophy and glomerular damage as well as classic "swan neck" lesions. Overall, Ctns-/- rats show a disease progression that more faithfully recapitulates nephropathic cystinosis than existing rodent models. The Ctns-/- rat provides an excellent new rodent model of nephropathic cystinosis that is ideally suited for conducting preclinical drug testing and is a powerful tool to advance cystinosis research.NEW & NOTEWORTHY Animal models of disease are essential to perform preclinical testing of new therapies before they can progress to clinical trials. The cystinosis field has been hampered by a lack of suitable animal models that fully recapitulate the disease. Here, we generated a rat model of cystinosis that closely models the human condition in a timeframe that makes them an excellent model for preclinical drug testing as well as being a powerful tool to advance research.


Assuntos
Sistemas de Transporte de Aminoácidos Neutros , Cistinose , Síndrome de Fanconi , Sistemas de Transporte de Aminoácidos Neutros/genética , Sistemas de Transporte de Aminoácidos Neutros/metabolismo , Animais , Cisteamina/farmacologia , Cisteamina/uso terapêutico , Cistina/genética , Cistina/metabolismo , Cistina/uso terapêutico , Cistinose/tratamento farmacológico , Cistinose/genética , Cistinose/metabolismo , Síndrome de Fanconi/genética , Fenótipo , Ratos
13.
Hepatology ; 73(4): 1290-1306, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33131062

RESUMO

BACKGROUND AND AIMS: The mechanisms by which the I148M mutant variant of the patatin-like phospholipase domain-containing 3 (PNPLA3I148M ) drives development of nonalcoholic steatohepatitis (NASH) are not known. The aim of this study was to obtain insights on mechanisms underlying PNPLA3I148M -induced acceleration of NASH. APPROACH AND RESULTS: Hepatocyte-specific overexpression of empty vector (luciferase), human wild-type PNPLA3, or PNPLA3I148M was achieved using adeno-associated virus 8 in a diet-induced mouse model of nonalcoholic fatty liver disease followed by chow diet or high-fat Western diet with ad libitum administration of sugar in drinking water (WDSW) for 8 weeks. Under WDSW, PNPLA3I148M overexpression accelerated steatohepatitis with increased steatosis, inflammation ballooning, and fibrosis (P < 0.001 versus other groups for all). Silencing PNPLA3I148M after its initial overexpression abrogated these findings. PNPLA3I148M caused 22:6n3 docosahexanoic acid depletion and increased ceramides under WDSW in addition to increasing triglycerides and diglycerides, especially enriched with unsaturated fatty acids. It also increased oxidative stress and endoplasmic reticulum stress. Increased total ceramides was associated with signature of transducer and activator of transcription 3 (STAT3) activation with downstream activation of multiple immune-inflammatory pathways at a transcriptomic level by network analyses. Silencing PNPLA3I148M reversed STAT3 activation. Conditioned media from HepG2 cells overexpressing PNPLA3I148M increased procollagen mRNA expression in LX2 cells; this was abrogated by hepatocyte STAT3 inhibition. CONCLUSIONS: Under WDSW, PNPLA3I148M overexpression promotes steatosis and NASH by metabolic reprogramming characterized by increased triglycerides and diglycerides, n3 polyunsaturated fatty acid depletion, and increased ceramides with resultant STAT3 phosphorylation and downstream inflammatory pathway activation driving increased stellate cell fibrogenic activity.


Assuntos
Lipase , Cirrose Hepática , Proteínas de Membrana , Hepatopatia Gordurosa não Alcoólica , Animais , Dieta Hiperlipídica/efeitos adversos , Dieta Ocidental/efeitos adversos , Modelos Animais de Doenças , Progressão da Doença , Expressão Gênica , Células Hep G2 , Células Estreladas do Fígado/metabolismo , Hepatócitos/metabolismo , Humanos , Lipase/genética , Cirrose Hepática/etiologia , Cirrose Hepática/metabolismo , Cirrose Hepática/patologia , Cirrose Hepática/fisiopatologia , Masculino , Proteínas de Membrana/genética , Camundongos , Camundongos Endogâmicos C57BL , Mutação , Hepatopatia Gordurosa não Alcoólica/etiologia , Hepatopatia Gordurosa não Alcoólica/genética , Hepatopatia Gordurosa não Alcoólica/metabolismo , Hepatopatia Gordurosa não Alcoólica/fisiopatologia , Polimorfismo Genético , Transcriptoma
14.
NMR Biomed ; 35(9): e4747, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35467776

RESUMO

To describe transverse relaxation of water in fixed tissue, we propose a model of transverse relaxation accelerated by diffusion and exchange (TRADE) that assumes exchange between free (visible) and bound (invisible) water, which relax by the dipole-dipole interaction, chemical exchange, and translation in the field gradient. Depending on the prevailing mechanism, transverse relaxation time (T2 ) of water in fixed tissue could increase (when dipole-dipole interaction prevails) or decrease with temperature (when diffusion in the field gradient prevails). Chemical exchange can make T2 even temperature independent. Also, variation of resolution from 100 to 15 µm/pxl (or less) affects effective transverse relaxation. T2 steadily decreases with increased resolution ( T 2 ∝ ∆ x 2 , ∆ x is the read direction resolution). TRADE can describe all of these observations (semi)quantitatively. The model has been experimentally verified on water phantoms and on formalin-fixed zebrafish, mouse brain, and rabbit larynx tissues. TRADE could help predict optimal scanning parameters for high-resolution MRM from much faster measurements at lower resolution.


Assuntos
Microscopia , Peixe-Zebra , Animais , Espectroscopia de Ressonância Magnética/métodos , Camundongos , Coelhos , Temperatura , Água
15.
Circ Res ; 127(12): 1502-1518, 2020 12 04.
Artigo em Inglês | MEDLINE | ID: mdl-33044128

RESUMO

RATIONALE: Cardiac pacemaker cells (PCs) in the sinoatrial node (SAN) have a distinct gene expression program that allows them to fire automatically and initiate the heartbeat. Although critical SAN transcription factors, including Isl1 (Islet-1), Tbx3 (T-box transcription factor 3), and Shox2 (short-stature homeobox protein 2), have been identified, the cis-regulatory architecture that governs PC-specific gene expression is not understood, and discrete enhancers required for gene regulation in the SAN have not been identified. OBJECTIVE: To define the epigenetic profile of PCs using comparative ATAC-seq (assay for transposase-accessible chromatin with sequencing) and to identify novel enhancers involved in SAN gene regulation, development, and function. METHODS AND RESULTS: We used ATAC-seq on sorted neonatal mouse SAN to compare regions of accessible chromatin in PCs and right atrial cardiomyocytes. PC-enriched assay for transposase-accessible chromatin peaks, representing candidate SAN regulatory elements, were located near established SAN genes and were enriched for distinct sets of TF (transcription factor) binding sites. Among several novel SAN enhancers that were experimentally validated using transgenic mice, we identified a 2.9-kb regulatory element at the Isl1 locus that was active specifically in the cardiac inflow at embryonic day 8.5 and throughout later SAN development and maturation. Deletion of this enhancer from the genome of mice resulted in SAN hypoplasia and sinus arrhythmias. The mouse SAN enhancer also directed reporter activity to the inflow tract in developing zebrafish hearts, demonstrating deep conservation of its upstream regulatory network. Finally, single nucleotide polymorphisms in the human genome that occur near the region syntenic to the mouse enhancer exhibit significant associations with resting heart rate in human populations. CONCLUSIONS: (1) PCs have distinct regions of accessible chromatin that correlate with their gene expression profile and contain novel SAN enhancers, (2) cis-regulation of Isl1 specifically in the SAN depends upon a conserved SAN enhancer that regulates PC development and SAN function, and (3) a corresponding human ISL1 enhancer may regulate human SAN function.


Assuntos
Arritmia Sinusal/metabolismo , Relógios Biológicos , Sequenciamento de Cromatina por Imunoprecipitação , Elementos Facilitadores Genéticos , Frequência Cardíaca , Proteínas com Homeodomínio LIM/metabolismo , Nó Sinoatrial/metabolismo , Fatores de Transcrição/metabolismo , Potenciais de Ação , Animais , Arritmia Sinusal/genética , Arritmia Sinusal/fisiopatologia , Epigênese Genética , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Idade Gestacional , Humanos , Proteínas com Homeodomínio LIM/genética , Masculino , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Polimorfismo de Nucleotídeo Único , Nó Sinoatrial/fisiopatologia , Fatores de Tempo , Fatores de Transcrição/genética , Peixe-Zebra/genética , Peixe-Zebra/metabolismo
16.
Diabetes Obes Metab ; 24(9): 1741-1752, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35546791

RESUMO

AIM: To determine whether hyperpolarization-activated cyclic nucleotide-gated (HCN) channels impact glucagon-like peptide-1 (GLP-1) receptor (GLP-1R) modulation of islet Ca2+ handling and insulin secretion. METHODS: The impact of liraglutide (GLP-1 analogue) on islet Ca2+ handling, HCN currents and insulin secretion was monitored with fluorescence microscopy, electrophysiology and enzyme immunoassays, respectively. Furthermore, liraglutide-mediated ß-to-δ-cell cross-communication was assessed following selective ablation of either mouse islet δ or ß cells. RESULTS: Liraglutide increased ß-cell Ca2+ oscillation frequency in mouse and human islets under stimulatory glucose conditions. This was dependent in part on liraglutide activation of HCN channels, which also enhanced insulin secretion. Similarly, liraglutide activation of HCN channels also increased ß-cell Ca2+ oscillation frequency in islets from rodents exposed to a diabetogenic diet. Interestingly, liraglutide accelerated Ca2+ oscillations in a majority of islet δ cells, which showed synchronized Ca2+ oscillations equivalent to ß cells; therefore, we assessed if either cell type was driving this liraglutide-mediated islet Ca2+ response. Although δ-cell loss did not impact liraglutide-mediated increase in ß-cell Ca2+ oscillation frequency, ß-cell ablation attenuated liraglutide-facilitated acceleration of δ-cell Ca2+ oscillations. CONCLUSION: The data presented here show that liraglutide-induced stimulation of islet HCN channels augments Ca2+ oscillation frequency. As insulin secretion oscillates with ß-cell Ca2+ , these findings have important implications for pulsatile insulin secretion that is probably enhanced by liraglutide activation of HCN channels and therapeutics that target GLP-1Rs for treating diabetes. Furthermore, these studies suggest that liraglutide as well as GLP-1-based therapies enhance δ-cell Ca2+ oscillation frequency and somatostatin secretion kinetics in a ß-cell-dependent manner.


Assuntos
Ilhotas Pancreáticas , Liraglutida , Animais , Peptídeo 1 Semelhante ao Glucagon/metabolismo , Receptor do Peptídeo Semelhante ao Glucagon 1/metabolismo , Humanos , Canais Disparados por Nucleotídeos Cíclicos Ativados por Hiperpolarização/metabolismo , Insulina/metabolismo , Secreção de Insulina , Ilhotas Pancreáticas/metabolismo , Liraglutida/farmacologia , Camundongos
17.
Environ Res ; 215(Pt 1): 114183, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36063910

RESUMO

BACKGROUND: Textile industries produce fabricated colored products using toxic dyes and other harsh chemicals. It is the responsibility of the textile industries to treat and eliminate these hazardous pollutants. However, due to the growing population demand, the treatment of these hazardous effluents is ineffective and imposes the treatment cost over the end users. The release of partially treated effluents in the environment may cause a severe threat to the ecology and its biota. The critical objective is to treat textile effluents efficiently using agricultural natural fiber waste. Generation of agricultural lignocellulosic fibrous waste increases every year due to growing population demand. Its use in the modern world is limited due to synthetic products. An alternative has enumerated to avoid wastage of fibrous resources and its clean disposal. OBJECTIVE: The main objective of this review paper discussed the feasibility of lignocellulosic fibers and other lignocellulosic materials as natural low-cost adsorbent. METHODS: The literature study was performed using Web of Science and Scopus indexed journals. The main factors considered to increase the adsorption ability, including the types of lignocellulosic surface modification techniques were searched with utmost importance for quality results. Intending to summarize the literature survey and provide persuasive content, systematic review process was considered for this novel article. RESULTS: Out of 230 valuable publications, 159 published articles were considered for the present study until March 2022. The articles surplus with factors affecting adsorption (pH, adsorption dosage, surface area, temperature, initial concentration, contact time, physical and chemical properties of pollutants) and surface modification techniques (physical, chemical, and biological) were considered for this manuscript. CONCLUSION: Overall, the physical and chemical modification methods are widely used instead of biological methods due to various factors as discussed briefly. Furthermore, the finding of this article supports the fact that the fibrous by-product resources are wasted in various occasions due to the modern lifestyle. Even though there is evidential possibility to implement the low-cost adsorbents, the industries limit their application prospects due to existing technology and financial compromises.


Assuntos
Poluentes Ambientais , Poluentes Químicos da Água , Adsorção , Corantes/química , Resíduos Industriais/análise , Lignina , Indústria Têxtil , Têxteis , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Poluentes Químicos da Água/análise
18.
J Cell Physiol ; 236(5): 3383-3395, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33145763

RESUMO

Apoptosis antagonizing transcription factor (AATF), an interacting partner of RNA polymerase II is a multifunctional protein that is highly conserved in eukaryotes. In addition to the regulation of gene expression as a transcriptional coactivator, AATF is shown to play a dual role in regulating the cell cycle by displacing histone deacetylases 1 (HDAC1) from the retinoblastoma-E2F transcription factor (Rb-E2F) complex and also from the specificity protein 1 (Sp1) transcription factor responsible for p21 expression, thereby ensuring cell proliferation and growth arrest, respectively, at different checkpoints of the cell cycle. Notably, AATF has emerged as one of the most important modulators of various cellular responses such as proliferation, apoptosis, and survival. Studies have demonstrated that AATF protects cells from multiple stress stimuli such as DNA damage, ER stress, hypoxia, or glucose deprivation by inducing cell cycle arrest, autophagy, or apoptosis inhibition. Furthermore, AATF serves as a critical regulator in various cancers and promotes tumorigenesis by protecting cancer cells from apoptosis induction, favoring cell proliferation, or promoting cell survival by autophagy. Recent studies have demonstrated the key role of AATF in ribosome biosynthesis and have also provided insights into the mechanistic role of AATF, offering impressive cytoprotection in myocardial infarction, neurologic diseases, and nephronophthisis. In this review, we will provide a comprehensive overview of the role of AATF and shed light on its emerging roles underlining the potential use of AATF as a novel biomarker and as an effective therapeutic target.


Assuntos
Proteínas Reguladoras de Apoptose/metabolismo , Pontos de Checagem do Ciclo Celular/fisiologia , Proliferação de Células/fisiologia , Fatores de Transcrição/metabolismo , Animais , Humanos , Proteínas Repressoras/genética , Transdução de Sinais/fisiologia
19.
J Physiol ; 598(21): 4887-4905, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32790176

RESUMO

KEY POINTS: Tetraspanin (TSPAN) proteins regulate many biological processes, including intracellular calcium (Ca2+ ) handling. TSPAN-7 is enriched in pancreatic islet cells; however, the function of islet TSPAN-7 has not been identified. Here, we characterize how ß-cell TSPAN-7 regulates Ca2+ handling and hormone secretion. We find that TSPAN-7 reduces ß-cell glucose-stimulated Ca2+ entry, slows Ca2+ oscillation frequency and decreases glucose-stimulated insulin secretion. TSPAN-7 controls ß-cell function through a direct interaction with L-type voltage-dependent Ca2+ channels (CaV 1.2 and CaV 1.3), which reduces channel Ca2+ conductance. TSPAN-7 slows activation of CaV 1.2 and accelerates recovery from voltage-dependent inactivation; TSPAN-7 also slows CaV 1.3 inactivation kinetics. These findings strongly implicate TSPAN-7 as a key regulator in determining the set-point of glucose-stimulated Ca2+ influx and insulin secretion. ABSTRACT: Glucose-stimulated insulin secretion (GSIS) is regulated by calcium (Ca2+ ) entry into pancreatic ß-cells through voltage-dependent Ca2+ (CaV ) channels. Tetraspanin (TSPAN) transmembrane proteins control Ca2+ handling, and thus they may also modulate GSIS. TSPAN-7 is the most abundant islet TSPAN and immunostaining of mouse and human pancreatic slices shows that TSPAN-7 is highly expressed in ß- and α-cells; however, the function of islet TSPAN-7 has not been determined. Here, we show that TSPAN-7 knockdown (KD) increases glucose-stimulated Ca2+ influx into mouse and human ß-cells. Additionally, mouse ß-cell Ca2+ oscillation frequency was accelerated by TSPAN-7 KD. Because TSPAN-7 KD also enhanced Ca2+ entry when membrane potential was clamped with depolarization, the effect of TSPAN-7 on CaV channel activity was examined. TSPAN-7 KD enhanced L-type CaV currents in mouse and human ß-cells. Conversely, heterologous expression of TSPAN-7 with CaV 1.2 and CaV 1.3 L-type CaV channels decreased CaV currents and reduced Ca2+ influx through both channels. This was presumably the result of a direct interaction of TSPAN-7 and L-type CaV channels because TSPAN-7 coimmunoprecipitated with both CaV 1.2 and CaV 1.3 from primary human ß-cells and from a heterologous expression system. Finally, TSPAN-7 KD in human ß-cells increased basal (5.6 mM glucose) and stimulated (45 mM KCl + 14 mM glucose) insulin secretion. These findings strongly suggest that TSPAN-7 modulation of ß-cell L-type CaV channels is a key determinant of ß-cell glucose-stimulated Ca2+ entry and thus the set-point of GSIS.


Assuntos
Células Secretoras de Glucagon , Células Secretoras de Insulina , Animais , Cálcio/metabolismo , Canais de Cálcio Tipo L/genética , Canais de Cálcio Tipo L/metabolismo , Células Secretoras de Glucagon/metabolismo , Glucose/metabolismo , Insulina/metabolismo , Secreção de Insulina , Células Secretoras de Insulina/metabolismo , Camundongos
20.
Hepatology ; 69(4): 1520-1534, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30394550

RESUMO

Hepatocellular carcinoma (HCC) is increasing as a cause of liver-related mortality largely because of the growing burden of nonalcoholic steatohepatitis (NASH). The mechanisms of HCC development in nonalcoholic fatty liver disease (NAFLD) are incompletely understood. We initially identified apoptosis antagonizing transcription factor (AATF) to be associated with HCC in a mouse model of NASH that develops HCC without the addition of specific carcinogens. AATF, also called che-1, is a transcriptional factor that is highly conserved among eukaryotes. AATF is known to be a central mediator of the cellular responses as it promotes cell proliferation and survival by inducing cell cycle arrest, autophagy, DNA repair, and inhibition of apoptosis. However, the role of AATF in NASH and HCC remains unknown. Here, we provide evidence for AATF as a contributory factor for HCC in NAFLD. AATF overexpression was further verified in human NASH and HCC and multiple human HCC cell lines. Tumor necrosis factor-α (TNFα), known to be increased in NASH, induced AATF expression. Promoter analysis of AATF revealed a sterol regulatory element binding transcription factor 1-c (SREBP-1c) binding site; inhibition of SREBP-1 by using specific inhibitors as well as small interfering RNA decreased TNFα-induced AATF expression. AATF interacted with signal transducer and activator of transcription 3 to increase monocyte chemoattractant protein-1 expression. AATF knockdown decreased cell proliferation, migration, invasion, colony formation, and anchorage-dependent growth in HCC cell lines. Xenograft of QGY-7703 HCC cells with AATF stably knocked down into nonobese diabetic scid gamma mice demonstrated reduced tumorigenesis and metastases. Conclusion: AATF drives NAFLD and hepatocarcinogenesis, offering a potential target for therapeutic intervention.


Assuntos
Proteínas Reguladoras de Apoptose/metabolismo , Carcinoma Hepatocelular/metabolismo , Neoplasias Hepáticas/metabolismo , Hepatopatia Gordurosa não Alcoólica/metabolismo , Proteínas Repressoras/metabolismo , Animais , Carcinoma Hepatocelular/etiologia , Quimiocina CCL2/metabolismo , Células Hep G2 , Humanos , Neoplasias Hepáticas/etiologia , Masculino , Camundongos , Hepatopatia Gordurosa não Alcoólica/complicações , Fator de Transcrição STAT3/metabolismo , Proteína de Ligação a Elemento Regulador de Esterol 1/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Regulação para Cima
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