Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 46
Filtrar
1.
Beilstein J Org Chem ; 19: 582-592, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37180458

RESUMO

The C3-functionalization of furfural using homogeneous ruthenium catalysts requires the preinstallation of an ortho-directing imine group, as well as high temperatures, which did not allow scaling up, at least under batch conditions. In order to design a safer process, we set out to develop a continuous flow process specifically for the C3-alkylation of furfural (Murai reaction). The transposition of a batch process to a continuous flow process is often costly in terms of time and reagents. Therefore, we chose to proceed in two steps: the reaction conditions were first optimized using a laboratory-built pulsed-flow system to save reagents. The optimized conditions in this pulsed-flow mode were then successfully transferred to a continuous flow reactor. In addition, the versatility of this continuous flow device allowed both steps of the reaction to be carried out, namely the formation of the imine directing group and the C3-functionalization with some vinylsilanes and norbonene.

2.
Nat Mater ; 20(9): 1216-1220, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-33958769

RESUMO

Extending the toolbox from mono- to bimetallic catalysts is key in realizing efficient chemical processes1. Traditionally, the performance of bimetallic catalysts featuring one active and one selective metal is optimized by varying the metal composition1-3, often resulting in a compromise between the catalytic properties of the two metals4-6. Here we show that by designing the atomic distribution of bimetallic Au-Pd nanocatalysts, we obtain a synergistic catalytic performance in the industrially relevant selective hydrogenation of butadiene. Our single-crystalline Au-core Pd-shell nanorods were up to 50 times more active than their alloyed and monometallic counterparts, while retaining high selectivity. We find a shell-thickness-dependent catalytic activity, indicating that not only the nature of the surface but also several subsurface layers play a crucial role in the catalytic performance, and rationalize this finding using density functional theory calculations. Our results open up an alternative avenue for the structural design of bimetallic catalysts.

3.
J Community Psychol ; 50(5): 2225-2242, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-34897694

RESUMO

The COVID-19 pandemic has had a significant impact on the lives of graduate student workers within university settings. At a large Midwestern private university, a Psychology Graduate Student Association (PsychGSA) identified that, in response to the pandemic, different levels of accommodations were being provided by faculty to graduate students. The PsychGSA conducted an evaluative survey that captured the experiences of 50 graduate students in the psychology department. The results highlight the inequitable challenges graduate students are currently facing. Recommendations to faculty to appropriately accommodate students during this unprecedented time, and beyond, are reported.


Assuntos
COVID-19 , Pandemias , Humanos , Estudantes , Universidades , Carga de Trabalho
4.
Small ; 17(51): e2104571, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34761525

RESUMO

The enhancement of the catalytic activity of gold nanoparticles with their decreasing size is often attributed to the increasing proportion of low-coordinated surface sites. This correlation is based on the paradigmatic picture of working gold nanoparticles as perfect crystal forms having complete and static outer surface layers whatever their size. This picture is incomplete as catalysts can dynamically change their structure according to the reaction conditions and as such changes can be eventually size-dependent. In this work, using aberration-corrected environmental electron microscopy, size-dependent crystal structure and morphological evolution in gold nanoparticles exposed to hydrogen at atmospheric pressure, with loss of the face-centered cubic crystal structure of gold for particle size below 4 nm, are revealed for the first time. Theoretical calculations highlight the role of mobile gold atoms in the observed symmetry changes and particle reshaping in the critical size regime. An unprecedented stable surface molecular structure of hydrogenated gold decorating a highly distorted core is identified. By combining atomic scale in situ observations and modeling of nanoparticle structure under relevant reaction conditions, this work provides a fundamental understanding of the size-dependent reactivity of gold nanoparticles with a precise picture of their surface at working conditions.


Assuntos
Ouro , Nanopartículas Metálicas , Pressão Atmosférica , Hidrogênio , Tamanho da Partícula
5.
Chem Rec ; 20(7): 660-671, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31833628

RESUMO

Nanoporous silica solids can offer opportunities for hosting photocatalytic components such as various tetra-coordinated transition metal ions to form systems referred to as "single-site photocatalysts". Under UV/visible-light irradiation, they form charge transfer excited states, which exhibit a localized charge separation and thus behave differently from those of bulk semiconductor photocatalysts exemplified by TiO2 . This account presents an overview of the design of advanced functional materials based on the unique photo-excited mechanisms of single-site photocatalysts. Firstly, the incorporation of single-site photocatalysts within transparent porous silica films will be introduced, which exhibit not only unique photocatalytic properties, but also high surface hydrophilicity with self-cleaning and antifogging applications. Secondary, photo-assisted deposition (PAD) of metal precursors on single-site photocatalysts opens up a new route to prepare nanoparticles. Thirdly, visible light sensitive photocatalysts with single and/or binary oxides moieties can be prepared so as to use solar light, the ideal energy source.

6.
Phys Chem Chem Phys ; 22(26): 14404-14414, 2020 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-32436501

RESUMO

As an environmentally friendly and renewable energy source, hydrogen peroxide (H2O2) could be produced photocatalytically through selective two-electron reduction of O2 using effective photocatalysts. Metal organic frameworks (MOFs), as hybrid porous materials consisting of organic linkers and metal oxide clusters, have aroused great interest in the design of effective catalysts for photocatalysis under visible light irradiation due to their unique properties, such as large surface area, good chemical stability, and diverse and tunable chemical components. In this perspective, we highlight our recent progress in the application of various MOF-based nanomaterials for photocatalytic H2O2 production from the selective two-electron reduction of O2 in a single-phase system (acetonitrile) and two-phase system (water/benzyl alcohol). Photocatalytic H2O2 production in the single-phase system achieved a higher activity using NiO as a cocatalyst of the MOF rather than Pt. Photocatalytic H2O2 production in the two-phase system using various hydrophobic MOFs showed further improved activity compared to the single-phase system. It has been possible to design a hydrophobic MOF-based photocatalyst with high activity and stability under recycling conditions. These studies gathered in this perspective revealed the novel application of MOFs in the field of energy production.

7.
Am J Med Genet A ; 176(4): 959-968, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29575626

RESUMO

Parents of children with the neurofibromatoses (NF; neurofibromatosis 1, neurofibromatosis 2, and schwannomatosis) are at an increased risk for emotional and physical health problems. This study aimed to determine parents' perceptions of stressors associated with parenting a child with NF in order to inform the development of a resiliency intervention. We conducted three live video semi structured focus groups with parents of youth with NF (N = 30), which were subsequently transcribed and coded using qualitative content analysis. Parents reported heightened stress associated with the child's educational, medical, and social needs, as well as concerns about their child's physical and mental health. They also reported stress associated with managing finances, multiple medical appointments, role challenges (i.e., being a parent or partner), and managing the uncertainty/unpredictability of their child's NF diagnosis. These stressors reportedly affected employment status (i.e., work scale backs), relationships (i.e., social, familial, with partner, other children), and the parents' physical and mental health. All participants expressed interest in a mind body program aimed at improving resiliency by teaching coping skills (e.g., mindfulness, adaptive thinking, positive psychology skills) and enhancing social support. Results show parents' enthusiasm for a resiliency intervention targeting stress associated with parenting a child with NF, and provide valuable information for the content of the intervention and its delivery modality.


Assuntos
Neurofibromatoses/epidemiologia , Relações Pais-Filho , Poder Familiar , Adaptação Psicológica , Adolescente , Criança , Progressão da Doença , Emoções , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Neurofibromatoses/diagnóstico , Pais/psicologia , Prognóstico , Estresse Psicológico
8.
J Neurooncol ; 137(2): 321-329, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29275505

RESUMO

The neurofibromatoses (NF) are incurable genetic disorders that can cause nerve sheath tumors, chronic pain, and disfiguration. Patients with NF report lower quality of life and greater distress, and may benefit from programs that promote resiliency. To test effects of an 8-week mind-body program (Relaxation Response Resiliency Program for NF [3RP-NF]) on resiliency, using data derived from a larger randomized controlled trial of the 3RP-NF versus attention placebo control (Vranceanu et al. in Neurology 87:806-814, 2016). Participants (N = 63; 46 female; 52 White) were randomized to 3RP-NF (n = 32, M age = 42.86) or control (n = 31, M age = 39.90), completed intervention sessions via group videoconferencing, and provided self-report measures of resiliency (i.e., perceived coping abilities, perceived social support, gratitude, optimism, spiritual well-being, mindfulness) at baseline, post-intervention, and 6-month follow-up. All participants attended at least 6/8 sessions and 83% (N = 52) provided 6-month follow-up data. The 3RP-NF (vs. control) produced greater improvements from pre- to post-intervention in perceived coping abilities (M difference = 6.68; p = .008), perceived social support (M difference = 9.16; p = .032), and mindfulness (M difference = 2.23; p = .035), which were maintained at 6-month follow up. We did not observe group differences in spiritual well-being, optimism, or gratitude. The 3RP-NF produced sustained increases in multiple dimensions of resiliency (perceived coping abilities, perceived social support, and mindfulness). Promoting resiliency may be particularly important for a population that is underserved and living with a chronic, incurable illness.


Assuntos
Terapias Mente-Corpo , Neurofibromatoses/psicologia , Neurofibromatoses/reabilitação , Resiliência Psicológica , Telemedicina , Adaptação Psicológica , Adulto , Feminino , Seguimentos , Humanos , Masculino , Atenção Plena , Qualidade de Vida , Resultado do Tratamento
9.
Cultur Divers Ethnic Minor Psychol ; 24(1): 15-25, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-28604021

RESUMO

OBJECTIVES: Psychosocial factors of trauma and abuse, racial discrimination, HIV stigma, and gender-related stressors (e.g., prioritizing others' needs) have been associated with antiretroviral treatment (ART) nonadherence and poor viral suppression among Black women living with HIV (BWLWH). To inform the development of an intervention addressing these psychosocial factors to improve ART adherence, the authors sought the insight of BWLWH. METHOD: Qualitative semistructured interviews were conducted with 30 BWLWH to gather information on their experiences with trauma, racism, HIV stigma, gender-related stressors, ART adherence, and coping strategies, and their insights on the proposed intervention. Participants' interviews were audio-recorded, transcribed, and coded using thematic content analysis and grounded theory. RESULTS: Participants shared (a) their experiences with trauma/abuse, racism, HIV-stigma, gender-related stress, and medication adherence; (b) coping strategies they use (e.g., social support, awareness [acknowledging systemic racism], assertiveness, selective disclosure of HIV status, and prioritizing the self); (c) how each of these adversities relate to their medication adherence and how they found ways to self-validate and practice self-primacy and self-care, including medication adherence in spite of adversities; and (d) enthusiasm for the proposed intervention. CONCLUSIONS: Culturally adapted interventions are needed to improve the health of BWLWH by enhancing coping strategies for the multiple adversities they face and promoting self-validation, self-primacy, and self-care in spite of adversities. (PsycINFO Database Record


Assuntos
Negro ou Afro-Americano/psicologia , Infecções por HIV/psicologia , Autocuidado/psicologia , Estigma Social , Sobreviventes/psicologia , Adaptação Psicológica , Adulto , Revelação , Feminino , HIV , Humanos , Masculino , Adesão à Medicação/psicologia , Apoio Social
10.
Phys Chem Chem Phys ; 17(42): 28022-32, 2015 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-25785784

RESUMO

Iridium was added to the Au/TiO2 system to try to enhance its catalytic activity in the reaction of propene oxidation, performed under conditions close to those used in the studies of decomposition of volatile organic compounds (1200 ppm propene and 9 vol% O2 in He). Titania supported Ir-Au (Ir/Au = 1) was prepared by sequential deposition-precipitation with urea (DPU) of Ir then Au. The effect of the activation conditions (hydrogen or air at 400 °C) was investigated. The study of the activation conditions of Ir-Au/TiO2 showed that activation under hydrogen at 400 °C generated a catalyst more active than the monometallic ones, while Ir-Au/TiO2 activated in air remained as poorly active as Au/TiO2. TEM characterization showed the formation of metallic particles of similar size (2-3 nm) in both monometallic Au/TiO2 and bimetallic Ir-Au/TiO2. Characterization especially by DRIFTS using CO as a probe molecule suggests the presence of Ir-Au interaction, IrO2-Au(0) interaction when the sample is calcined and Ir(0)-Au(0) bimetallic particles when it is reduced. XPS and TPR characterization techniques showed that gold hinders to some extent the reoxidation of iridium in the reduced bimetallic Ir-Au/TiO2 catalyst. The enhanced catalytic activity of the reduced bimetallic Ir-Au/TiO2 catalyst is attributed to a surface Ir(0)-Au(0) synergism.

11.
J Biol Chem ; 288(6): 4389-404, 2013 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-23266826

RESUMO

The inhibition of MyoD expression is important for obtaining muscle progenitors that can replenish the satellite cell niche during muscle repair. Progenitors could be derived from either embryonic stem cells or satellite cells. Hedgehog (Hh) signaling is important for MyoD expression during embryogenesis and adult muscle regeneration. To date, the mechanistic understanding of MyoD regulation by Hh signaling is unclear. Here, we demonstrate that the Hh effector, Gli2, regulates MyoD expression and associates with MyoD gene elements. Gain- and loss-of-function experiments in pluripotent P19 cells show that Gli2 activity is sufficient and required for efficient MyoD expression during skeletal myogenesis. Inhibition of Hh signaling reduces MyoD expression during satellite cell activation in vitro. In addition to regulating MyoD expression, Hh signaling regulates MyoD transcriptional activity, and MyoD activates Hh signaling in myogenic conversion assays. Finally, Gli2, MyoD, and MEF2C form a protein complex, which enhances MyoD activity on skeletal muscle-related promoters. We therefore link Hh signaling to the function and expression of MyoD protein during myogenesis in stem cells.


Assuntos
Regulação da Expressão Gênica/fisiologia , Proteínas Hedgehog/metabolismo , Proteína MyoD/biossíntese , Células-Tronco Pluripotentes/metabolismo , Células Satélites de Músculo Esquelético/metabolismo , Transdução de Sinais/fisiologia , Animais , Linhagem Celular , Proteínas Hedgehog/genética , Fatores de Transcrição Kruppel-Like/genética , Fatores de Transcrição Kruppel-Like/metabolismo , Fatores de Transcrição MEF2 , Camundongos , Camundongos Transgênicos , Complexos Multiproteicos/genética , Complexos Multiproteicos/metabolismo , Desenvolvimento Muscular/fisiologia , Fatores de Regulação Miogênica/genética , Fatores de Regulação Miogênica/metabolismo , Células-Tronco Pluripotentes/citologia , Células Satélites de Músculo Esquelético/citologia , Proteína Gli2 com Dedos de Zinco
12.
Phys Chem Chem Phys ; 16(48): 26514-27, 2014 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-25051298

RESUMO

Oxide supported copper and gold catalysts are active for the selective hydrogenation of polyunsaturated hydrocarbons but their low activity compared to palladium catalysts and the deactivation of copper catalysts limit their use. There are only a very limited number of studies concerned with the use of bimetallic Au-Cu catalysts for selective hydrogenation reactions and the aim of this work was to prepare TiO2-supported monometallic Au and Cu and bimetallic AuCu (Cu/Au atomic ratio of 1 and 3) catalysts and to evaluate their catalytic performance in the selective hydrogenation of butadiene. Small gold, copper and gold-copper nanoparticles (average particle size < 2 nm) were obtained on TiO2 using the preparation method of deposition-precipitation with urea followed by reduction under H2 at 300 °C. Very small clusters were observed for Cu/TiO2 (∼1 nm) which might result from O2 induced copper redispersion, as also supported by the XPS analyses. The alloying of copper with gold was found to inhibit its redispersion and also limits its reoxidation, as attested by XPS. The bimetallic character of the AuCu nanoparticles was confirmed by XPS and EDX-HAADF. Cu/TiO2 was initially more active than Au/TiO2 in the selective hydrogenation of butadiene at 75 °C but it deactivated rapidly during the first hours of reaction whereas the gold catalyst was very stable up to 20 hours of reaction. The bimetallic AuCu/TiO2 catalysts displayed an activation period during the first hours of the reaction, which was very pronounced for the sample containing a higher Cu/Au atomic ratio. This initial gain in activity was tentatively assigned to copper segregation at the surface of the bimetallic nanoparticles, induced by the reactants. When the AuCu/TiO2 catalysts were pre-exposed to air at 75 °C before butadiene hydrogenation, surface copper segregation occurred, leading to higher initial activity and the suppression of the activation period. Under the same conditions, Cu/TiO2 totally lost its activity, probably due to irreversible copper oxidation.

13.
Stem Cells ; 30(12): 2619-30, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23034923

RESUMO

Upon injury, muscle satellite cells become activated and produce skeletal muscle precursors that engage in myogenesis. We demonstrate that the transcription factor CCAAT/enhancer binding protein beta (C/EBPß) is expressed in the satellite cells of healthy muscle. C/EBPß expression is regulated during myogenesis such that C/EBPß is rapidly and massively downregulated upon induction to differentiate. Furthermore, persistent expression of C/EBPß in myoblasts potently inhibits differentiation at least in part through the inhibition of MyoD protein function and stability. As a consequence, myogenic factor expression, myosin heavy chain expression, and fusogenic activity were reduced in C/EBPß-overexpressing cells. Using knockout models, we demonstrate that loss of Cebpb expression in satellite cells results in precocious differentiation of myoblasts in growth conditions and greater cell fusion upon differentiation. In vivo, loss of Cebpb expression in satellite cells resulted in larger muscle fiber cross-sectional area and improved repair after muscle injury. Our results support the notion that C/EBPß inhibits myogenic differentiation and that its levels must be reduced to allow for activation of MyoD target genes and the progression of differentiation.


Assuntos
Proteína beta Intensificadora de Ligação a CCAAT/biossíntese , Células Satélites de Músculo Esquelético/citologia , Células Satélites de Músculo Esquelético/metabolismo , Animais , Diferenciação Celular/fisiologia , Células Cultivadas , Feminino , Camundongos , Camundongos Endogâmicos C57BL , Desenvolvimento Muscular/fisiologia , Músculo Esquelético/citologia , Músculo Esquelético/metabolismo , Proteína MyoD/metabolismo
14.
Phys Chem Chem Phys ; 15(10): 3473-9, 2013 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-23361459

RESUMO

Gold catalysts supported on titania (Au-TiO(2)) and alumina (Au-Al(2)O(3)) were prepared by deposition-precipitation with urea and then activated before characterisation and reaction in CO oxidation, either by calcination in air at 500 °C or reduction under H(2) at 300 °C. Gold nanoparticles with average size in the range 2-4 nm were obtained, with calcination leading to larger gold nanoparticles than reduction. For Au-TiO(2), high activity was observed in CO oxidation at room temperature, independent of the activation treatment. This high activity could not be correlated to the presence of sub-nanometer gold clusters as reported in the literature, since they could not be detected by atomic-resolution high-angle annular dark-field scanning-transmission electron microscopy (HAADF-STEM). In the case of Au-Al(2)O(3), the performance in CO oxidation was found to strongly depend on the water content in the reaction gas feed and on the activation conditions, with calcination resulting in a poorly active catalyst whereas reduction gave activity of the same order as Au-TiO(2). A comparative study of Au-TiO(2) and Au-Al(2)O(3) by electron microscopy did not reveal distinct differences in the shapes of the Au nanoparticles, which are mostly flattened through interaction with the substrate in both samples, with side profile shapes varying from rounded hemispherical to well faceted truncated cubo-octahedra. More faceting is found for the samples calcined at 500 °C than reduced at 300 °C. Various possible parameters affecting the catalytic properties of gold in CO oxidation are discussed in the context of the relevant literature.

15.
Trauma Violence Abuse ; 24(3): 1966-1985, 2023 07.
Artigo em Inglês | MEDLINE | ID: mdl-35465774

RESUMO

While rape crisis center (RCC) advocacy is generally regarded as valuable, there are no prior systematic reviews of the advocacy literature. This review examined RCC advocacy service provision, perceptions and impact of advocacy, and challenges and facilitators to effective service provision. Databases related to health and social sciences were searched including Academic Search Complete, PsychINFO, PubMed, CINAHL, ProQuest, Science Direct, OAlster, WorldCat, and MEDLINE. Empirical articles written in English that examined RCC advocacy service provision and/or impact in the US were included. The researchers reviewed abstracts and titles, and then full texts. Forty-five articles met criteria, were summarized, and double checked. Findings demonstrate advocacy is multi-faceted, beneficial, and challenging. Advocates work directly with survivors and interact with other responders on behalf of survivors. Specifically, advocates provide emotional support, safety plan, support survivors in making decisions, and assist them in navigating other systems. While advocates are generally regarded positively by survivors and responders, some responders have concerns about advocates. In addition, advocates sometimes report victim-blaming and being ill-equipped to meet survivors' needs. Finally, advocates face specific challenges in their work with survivors and responders. Future research using diverse methodological approaches is needed to understand advocacy utilization and reach; survivors' perceptions of advocacy; marginalized survivors' experiences; connections between specific services, implementation, and outcomes; and effective strategies for advocates' interactions with other responders. Additional resources to help advocates serve all survivors effectively and equitably; to support evaluator-practitioner partnerships; and to share unpublished data on advocacy may help contribute to improvements in advocacy practice.


Assuntos
Carcinoma de Células Renais , Neoplasias Renais , Estupro , Humanos , Estupro/psicologia , Defesa do Paciente , Sobreviventes/psicologia
16.
Cell Rep ; 42(10): 113191, 2023 10 31.
Artigo em Inglês | MEDLINE | ID: mdl-37792528

RESUMO

In solid tumors, drug concentrations decrease with distance from blood vessels. However, cellular adaptations accompanying the gradated exposure of cancer cells to drugs are largely unknown. Here, we modeled the spatiotemporal changes promoting chemotherapy resistance in breast cancer. Using pairwise cell competition assays at each step during the acquisition of chemoresistance, we reveal an important priming phase that renders cancer cells previously exposed to sublethal drug concentrations refractory to dose escalation. Therapy-resistant cells throughout the concentration gradient display higher expression of the solute carriers SLC38A7 and SLC46A1 and elevated intracellular concentrations of their associated metabolites. Reduced levels of SLC38A7 and SLC46A1 diminish the proliferative potential of cancer cells, and elevated expression of these SLCs in breast tumors from patients correlates with reduced survival. Our work provides mechanistic evidence to support dose-intensive treatment modalities for patients with solid tumors and reveals two members of the SLC family as potential actionable targets.


Assuntos
Neoplasias da Mama , Neoplasias Mamárias Animais , Animais , Humanos , Feminino , Resistencia a Medicamentos Antineoplásicos/genética , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Mama/metabolismo , Transportador de Folato Acoplado a Próton
17.
iScience ; 26(4): 106314, 2023 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-37009228

RESUMO

Skin plays central roles in systemic physiology, and it undergoes significant functional changes during aging. Members of the peroxisome proliferator-activated receptor-gamma coactivator (PGC-1) family (PGC-1s) are key regulators of the biology of numerous tissues, yet we know very little about their impact on skin functions. Global gene expression profiling and gene silencing in keratinocytes uncovered that PGC-1s control the expression of metabolic genes as well as that of terminal differentiation programs. Glutamine emerged as a key substrate promoting mitochondrial respiration, keratinocyte proliferation, and the expression of PGC-1s and terminal differentiation programs. Importantly, gene silencing of PGC-1s reduced the thickness of a reconstructed living human epidermal equivalent. Exposure of keratinocytes to a salicylic acid derivative potentiated the expression of PGC-1s and terminal differentiation genes and increased mitochondrial respiration. Overall, our results show that the PGC-1s are essential effectors of epidermal physiology, revealing an axis that could be targeted in skin conditions and aging.

18.
Blood Adv ; 7(14): 3485-3500, 2023 07 25.
Artigo em Inglês | MEDLINE | ID: mdl-36920785

RESUMO

Multiple myeloma (MM) is a hematological malignancy that emerges from antibody-producing plasma B cells. Proteasome inhibitors, including the US Food and Drug Administration-approved bortezomib (BTZ) and carfilzomib (CFZ), are frequently used for the treatment of patients with MM. Nevertheless, a significant proportion of patients with MM are refractory or develop resistance to this class of inhibitors, which represents a significant challenge in the clinic. Thus, identifying factors that determine the potency of proteasome inhibitors in MM is of paramount importance to bolster their efficacy in the clinic. Using genome-wide CRISPR-based screening, we identified a subunit of the mitochondrial pyruvate carrier (MPC) complex, MPC1, as a common modulator of BTZ response in 2 distinct human MM cell lines in vitro. We noticed that CRISPR-mediated deletion or pharmacological inhibition of the MPC complex enhanced BTZ/CFZ-induced MM cell death with minimal impact on cell cycle progression. In fact, targeting the MPC complex compromised the bioenergetic capacity of MM cells, which is accompanied by reduced proteasomal activity, thereby exacerbating BTZ-induced cytotoxicity in vitro. Importantly, we observed that the RNA expression levels of several regulators of pyruvate metabolism were altered in advanced stages of MM for which they correlated with poor patient prognosis. Collectively, this study highlights the importance of the MPC complex for the survival of MM cells and their responses to proteasome inhibitors. These findings establish mitochondrial pyruvate metabolism as a potential target for the treatment of MM and an unappreciated strategy to increase the efficacy of proteasome inhibitors in the clinic.


Assuntos
Antineoplásicos , Mieloma Múltiplo , Estados Unidos , Humanos , Inibidores de Proteassoma/farmacologia , Inibidores de Proteassoma/uso terapêutico , Mieloma Múltiplo/tratamento farmacológico , Mieloma Múltiplo/patologia , Antineoplásicos/uso terapêutico , Transportadores de Ácidos Monocarboxílicos/uso terapêutico , Bortezomib/farmacologia , Bortezomib/uso terapêutico , Piruvatos/uso terapêutico
19.
Differentiation ; 82(2): 57-65, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21612856

RESUMO

Mesenchymal stem cells are pluripotent precursor cells that can differentiate into osteoblasts, adipocytes, chondrocytes and myocytes. Despite their important therapeutic potential little is known about the transcriptional cascades that govern lineage decisions in these cells. Treatment of C3H10T1/2 mouse mesenchymal stem cells with retinoic acid (RA) inhibits adipogenesis and enhances osteoblastogenesis. In particular, RA treatment stimulates the expression of the osteoblast master regulator, runt-related transcription factor 2 (Runx2), whose expression is necessary for the formation of bone. We have shown previously in mesenchymal stem cells that RA acts to stimulate osteoblastogenesis by interfering with the actions of the bzip transcription factor CCAAT/Enhancer Binding Protein beta (C/EBPß), where it binds to a negative regulatory element within the Runx2 promoter and inhibits its expression. Herein we show that Smad3, whose expression is stimulated by RA, relays the effects of RA on differentiation by initiating the displacement of C/EBPß from the Runx2 promoter. In addition to stimulating Smad3 expression, RA also stimulated the nuclear localization of this factor, such that in the absence of RA, ectopic Smad3 was unable to drive osteoblastogenesis. While not sufficient to promote osteoblastogenesis, knockdown of Smad3 using a specific shRNA prevented the RA-mediated stimulation of differentiation and displacement of C/EBPß from the Runx2 P1 promoter. Taken together, these data indicate that Smad3 is an important mediator of RA activity during mesenchymal stem cell differentiation and is necessary for the stimulation of osteoblastogenesis.


Assuntos
Diferenciação Celular/efeitos dos fármacos , Células-Tronco Mesenquimais/citologia , Osteoblastos/citologia , Proteína Smad3/metabolismo , Tretinoína/farmacologia , Adipogenia/efeitos dos fármacos , Adipogenia/genética , Animais , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Linhagem Celular , Subunidade alfa 1 de Fator de Ligação ao Core/genética , Subunidade alfa 1 de Fator de Ligação ao Core/metabolismo , Regulação da Expressão Gênica , Peptídeos e Proteínas de Sinalização Intracelular , Células-Tronco Mesenquimais/metabolismo , Camundongos , Camundongos Endogâmicos C3H , Osteoblastos/metabolismo , Regiões Promotoras Genéticas , Proteínas de Ligação a RNA , Proteína Smad3/antagonistas & inibidores , Proteína Smad3/genética
20.
J Biol Chem ; 285(17): 13274-84, 2010 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-20179325

RESUMO

The process of adipocyte differentiation is driven by a highly coordinated cascade of transcriptional events that results in the development of the mature adipocyte and in lipid accumulation. One of the early events of differentiation is the up-regulation of CCAAT/enhancer-binding protein beta (C/EBPbeta) expression. C/EBPbeta then acts to up-regulate the expression of adipogenic factors such as C/EBPalpha, which control the late stage of adipogenesis. Retinoic acid (RA) is a potent inhibitor of adipogenesis, and its action appears to block C/EBPbeta transcriptional potential early during differentiation. Using preadipocytes and mesenchymal stem cell models, we show that RA specifically blocks the occupancy of C/EBPbeta of the Cebpa promoter, thereby abrogating the differentiation process. RA does not act directly on C/EBPbeta but rather stimulates the expression of the transforming growth factor beta-effector protein Smad3, which can interact with C/EBPbeta via its Mad homology 1 domain and can interfere with C/EBPbeta DNA binding. The RA-induced increase in Smad3 expression results in increased cytoplasmic and nuclear Smad3, an important event as ectopic expression of Smad3 in preadipocytes in the absence of RA treatment only modestly inhibits adipogenesis and C/EBPbeta DNA binding, suggesting that Smad3 alone is not sufficient to completely recapitulate the effects of retinoic acid treatment during differentiation. However, in the absence of Smad3, RA is not able to inhibit adipocyte differentiation or to elicit a decrease in C/EBPbeta DNA occupancy suggesting that Smad3 is necessary to convey the inhibitory effects of retinoic acid during adipogenesis.


Assuntos
Adipócitos/metabolismo , Adipogenia/efeitos dos fármacos , Antineoplásicos/farmacologia , Células-Tronco Mesenquimais/metabolismo , Proteína Smad3/metabolismo , Tretinoína/farmacologia , Células 3T3-L1 , Adipogenia/fisiologia , Animais , Proteína beta Intensificadora de Ligação a CCAAT/genética , Proteína beta Intensificadora de Ligação a CCAAT/metabolismo , Diferenciação Celular/efeitos dos fármacos , Diferenciação Celular/fisiologia , Núcleo Celular/genética , Núcleo Celular/metabolismo , Citoplasma/genética , Citoplasma/metabolismo , Camundongos , Modelos Biológicos , Células NIH 3T3 , Regiões Promotoras Genéticas/fisiologia , Proteína Smad3/genética , Regulação para Cima/efeitos dos fármacos , Regulação para Cima/genética
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA