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1.
Adv Mater ; : e2403875, 2024 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-39051946

RESUMO

CsPbBr3 exhibits outstanding optoelectronic properties and thermal stability, making it a coveted material for detectors, light-emitting diodes, and solar cells. Despite observations of ferroelectricity in CsPbBr3 quantum dots, synthesizing bulk ferroelectric CsPbBr3 crystals has remained elusive, hindering its potential in next-generation optoelectronic devices like optical switches and ferroelectric photovoltaics. Here, a breakthrough is reported: a novel solvothermal technique enabling the growth of ferroelectric CsPbBr3 nanoplatelets with lateral dimensions in the tens of micrometers. This represents a significant step toward achieving large-area ferroelectric CsPbBr3 crystals. Unlike traditional methods, this approach allows for growth and crystallization of CsPbBr3 in alcohol solutions by enhancing precursor solubility. This study confirms the ferroelectric nature of these nanoplatelets using second harmonic generation, electrical characterizations, and piezoresponse force microscopy. This work paves the way for utilizing ferroelectric CsPbBr3 in novel optoelectronic devices, significantly expanding the potential of this material and opening doors for further exploration in this exciting field.

2.
iScience ; 27(6): 109995, 2024 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-38868185

RESUMO

The canonical mechanism behind tamoxifen's therapeutic effect on estrogen receptor α/ESR1+ breast cancers is inhibition of ESR1-dependent estrogen signaling. Although ESR1+ tumors expressing wild-type p53 were reported to be more responsive to tamoxifen (Tam) therapy, p53 has not been factored into choice of this therapy and the mechanism underlying the role of p53 in Tam response remains unclear. In a window-of-opportunity trial on patients with newly diagnosed stage I-III ESR1+/HER2/wild-type p53 breast cancer who were randomized to arms with or without Tam prior to surgery, we reveal that the ESR1-p53 interaction in tumors was inhibited by Tam. This resulted in functional reactivation of p53 leading to transcriptional reprogramming that favors tumor-suppressive signaling, as well as downregulation of oncogenic pathways. These findings illustrating the convergence of ESR1 and p53 signaling during Tam therapy enrich mechanistic understanding of the impact of p53 on the response to Tam therapy.

3.
iScience ; 27(3): 109187, 2024 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-38420590

RESUMO

Tissue-resident macrophages (TRMs) are abundant immune cells within pre-metastatic sites, yet their functional contributions to metastasis remain incompletely understood. Here, we show that alveolar macrophages (AMs), the main TRMs of the lung, are susceptible to downregulation of the immune stimulatory transcription factor IRF8, impairing anti-metastatic activity in models of metastatic breast cancer. G-CSF is a key tumor-associated factor (TAF) that acts upon AMs to reduce IRF8 levels and facilitate metastasis. Translational relevance of IRF8 downregulation was observed among macrophage precursors in breast cancer and a CD68hiIRF8loG-CSFhi gene signature suggests poorer prognosis in triple-negative breast cancer (TNBC), a G-CSF-expressing subtype. Our data highlight the underappreciated, pro-metastatic roles of AMs in response to G-CSF and identify the contribution of IRF8-deficient AMs to metastatic burden. AMs are an attractive target of local neoadjuvant G-CSF blockade to recover anti-metastatic activity.

4.
Nanotechnology ; 35(7)2023 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-37949048

RESUMO

Bismuth oxyselenide has recently gained tremendous attention as a promising 2D material for next-generation electronic and optoelectronic devices due to its ultrahigh mobility, moderate bandgap, exceptional environmental stability, and presence of high-dielectric constant native oxide. In this study, we have synthesized single-crystalline nanosheets of Bismuth oxyselenide with thicknesses measuring below ten nanometers on Fluorophlogopite mica using an atmospheric pressure chemical vapor deposition system. We transferred as-grown samples to different substrates using a non-corrosive nail polish-assisted dry transfer method. Back-gated Bi2O2Se field effect transistors showed decent field effect mobility of 100 cm2V-1s-1. The optoelectronic property study revealed an ultrahigh responsivity of 1.16 × 106A W-1and a specific detectivity of 2.55 × 1013Jones. The samples also exhibited broadband photoresponse and gate-tunable photoresponse time. These results suggest that Bi2O2Se is an excellent candidate for future high-performance optoelectronic device applications.

5.
Nanotechnology ; 34(50)2023 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-37708882

RESUMO

The reduced dielectric screening in atomically thin two-dimensional materials makes them very sensitive to the surrounding environment, which can be modulated to tune their optoelectronic properties. In this study, we significantly improved the optoelectronic properties of monolayer MoS2by varying the surrounding environment using different liquid dielectrics, each with a specific dielectric constant ranging from 1.89 to 18. Liquid mediums offer the possibility of environment tunability on the same device. For a back-gated field effect transistor, the field effect mobility exhibited more than two-order enhancement when exposed to a high dielectric constant medium. Further investigation into the effect of the dielectric environment on the optoelectronic properties demonstrated a variation in photoresponse relaxation time with the dielectric medium. The rise and decay times were observed to increase and decrease, respectively, with an increase in the dielectric constant of the medium. These results can be attributed to the dielectric screening provided by the surrounding medium, which strongly modifies the charged impurity scattering, the band gap, and defect levels of monolayer MoS2. These findings have important implications for the design of biological and chemical sensors, particularly those operating in a liquid environment. By leveraging the tunability of the dielectric medium, we can optimize the performance of such sensors and enhance their detection capabilities.

6.
Sci Transl Med ; 15(686): eabl4414, 2023 03 08.
Artigo em Inglês | MEDLINE | ID: mdl-36888695

RESUMO

Natural killer (NK) cells are cytotoxic lymphocytes that accumulate within the tumor microenvironment and are generally considered to be antitumorigenic. Using single-cell RNA sequencing and functional analysis of multiple triple-negative breast cancer (TNBC) and basal tumor samples, we observed a unique subcluster of Socs3highCD11b-CD27- immature NK cells that were present only in TNBC samples. These tumor-infiltrating NK cells expressed a reduced cytotoxic granzyme signature and, in mice, were responsible for activating cancer stem cells through Wnt signaling. NK cell-mediated activation of these cancer stem cells subsequently enhanced tumor progression in mice, whereas depletion of NK cells or Wnt ligand secretion from NK cells by LGK-974 decreased tumor progression. In addition, NK cell depletion or inhibition of their function improved anti-programmed cell death ligand 1 (PD-L1) antibody or chemotherapy response in mice with TNBC. Furthermore, tumor samples from patients with TNBC and non-TNBC revealed that increased numbers of CD56bright NK cells were present in TNBC tumors and were correlated to poor overall survival in patients with TNBC. Together, our findings identify a population of protumorigenic NK cells that may be exploited for both diagnostic and therapeutic strategies to improve outcomes for patients with TNBC.


Assuntos
Antineoplásicos , Neoplasias de Mama Triplo Negativas , Humanos , Animais , Camundongos , Neoplasias de Mama Triplo Negativas/tratamento farmacológico , Antineoplásicos/uso terapêutico , Células Matadoras Naturais , Antígeno B7-H1/metabolismo , Microambiente Tumoral
7.
Oncologist ; 28(4): 358-363, 2023 04 06.
Artigo em Inglês | MEDLINE | ID: mdl-36772966

RESUMO

The absence of effective therapeutic targets and aggressive nature of triple-negative breast cancer (TNBC) renders this disease subset difficult to treat. Although estrogen receptor beta (ERß) is expressed in TNBC, studies on its functional role have yielded inconsistent results. However, recently, our preclinical studies, along with other observations, have shown the potential therapeutic utility of ERß in the context of mutant p53 expression. The current case study examines the efficacy of the selective estrogen receptor modulator tamoxifen in p53-mutant TNBC with brain metastases. Significant increase in ERß protein expression and anti-proliferative interaction between mutant p53 and ERß were observed after cessation of tamoxifen therapy, with significant regression of brain metastases. This case study provides supporting evidence for the use of tamoxifen in p53-mutant, ERß+TNBC, especially in the setting of brain metastasis.


Assuntos
Neoplasias da Mama , Neoplasias de Mama Triplo Negativas , Feminino , Humanos , Neoplasias da Mama/metabolismo , Linhagem Celular Tumoral , Receptor alfa de Estrogênio , Receptor beta de Estrogênio/genética , Receptor beta de Estrogênio/metabolismo , Receptor beta de Estrogênio/uso terapêutico , Tamoxifeno/farmacologia , Tamoxifeno/uso terapêutico , Neoplasias de Mama Triplo Negativas/tratamento farmacológico , Neoplasias de Mama Triplo Negativas/genética , Proteína Supressora de Tumor p53/genética
8.
J Phys Chem Lett ; 14(7): 1870-1876, 2023 Feb 23.
Artigo em Inglês | MEDLINE | ID: mdl-36779963

RESUMO

Hybrid lead halide perovskites and their derivatives are important optoelectronic materials but suffer from water instability. Combining both the optoelectronics and the water stability of such systems is a major challenge in material design today. To address this issue, we employ the well-known π-conjugation and cation-π interaction concepts in designing a hybrid lead halide perovskite derivative system. (4,4'-VDP)Pb2Br6 (VDP = vinylenedipyridinium) single crystals are prepared. They have a one-dimensional (1D) arrangement of inorganic Pb-Br sublattices connected via the 4,4'-VDP organic sublattice. The π-conjugation in the 4,4'-VDP sublattice allows electronic communication between the 1D Pb-Br units, reducing the band gap and improving the photoconductivity. Importantly, N+ of one 4,4'-VDP molecular ion interacts with the π-electron cloud of the adjacent one. This intermolecular cation-π interaction extends throughout the organic sublattice, making the hybrid crystal stable when stored under water for more than a year without requiring any encapsulations.

9.
J Am Chem Soc ; 145(2): 1378-1388, 2023 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-36594717

RESUMO

Structural non-centrosymmetry in semiconducting organic-inorganic hybrid halide perovskites can introduce functionalities like anomalous photovoltaics and nonlinear optical properties. Here we introduce a design principle to prepare Pb- and Bi-based two- and one-dimensional hybrid perovskites with polar non-centrosymmetric space groups. The design principle relies on creating dissimilar hydrogen and halogen bonding non-covalent interactions at the organic-inorganic interface. For example, in organic cations like I-(CH2)3-NH2(CH3)+ (MIPA), -CH3 is substituted by -CH2I at one end, and -NH3+ is substituted by -NH2(CH3)+ at the other end. These substitutions of two -H atoms by -I and -CH3 reduce the rotational symmetry of MIPA at both ends, compared to an unsubstituted cation, for example, H3C-(CH2)3-NH3+. Consequently, the dissimilar hydrogen-iodine and iodine-iodine interactions at the organic-inorganic interface of (MIPA)2PbI4 2D perovskites break the local inversion symmetries of Pb-I octahedra. Owing to this non-centrosymmetry, (MIPA)2PbI4 displays visible to infrared tunable nonlinear optical properties with second and third harmonic generation susceptibility values of 5.73 pm V-1 and 3.45 × 10-18 m2 V-2, respectively. Also, the single crystal shows photocurrent on shining visible light at no external bias, exhibiting anomalous photovoltaic effect arising from the structural asymmetry. The design strategy was extended to synthesize four new non-centrosymmetric hybrid perovskite compounds. Among them, one-dimensional (H3N-(CH2)3-NH(CH3)2)BiI5 shows a second harmonic generation susceptibility of 7.3 pm V-1 and a high anomalous photovoltaic open-circuit voltage of 22.6 V.

10.
Cancers (Basel) ; 14(5)2022 02 22.
Artigo em Inglês | MEDLINE | ID: mdl-35267428

RESUMO

High grade serous ovarian cancer (HGSOC) is the most common and lethal subtype of epithelial ovarian cancer. Prevalence (~96%) of mutant p53 is a hallmark of HGSOC. Estrogen receptor-beta (ERß) has been reported to be another important player in HGSOC, although the pro-versus anti-tumorigenic role of its different isoforms remains unsettled. However, whether there is functional interaction between ERß and mutant p53 in HGSOC is unknown. ERß1 and ERß2 mRNA and protein analysis in HGSOC cell lines demonstrated that ERß2 is the predominant isoform in HGSOC. Specificity of ERß2 antibody was ascertained using cells depleted of ERß2 and ERß1 separately with isoform-specific siRNAs. ERß2-mutant p53 interaction in cell lines was confirmed by co-immunoprecipitation and in situ proximity ligation assay (PLA). Expression levels of ERß2, ERα, p53, and FOXM1 proteins and ERß2-mutant p53 interaction in patient tumors were determined by immunohistochemistry (IHC) and PLA, respectively. ERß2 levels correlate positively with FOXM1 levels and negatively with progression-free survival (PFS) and overall survival (OS). Quantitative chromatin immunoprecipitation (qChIP) and mRNA expression analysis revealed that ERß2 and mutant p53 co-dependently regulated FOXM1 gene transcription. The combination of ERß2-specific siRNA and PRIMA-1MET that converts mutant p53 to wild type conformation increased apoptosis. Our work provides the first evidence for a novel ERß2-mutant p53-FOXM1 axis that can be exploited for new therapeutic strategies against HGSOC.

11.
Cancers (Basel) ; 13(14)2021 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-34298826

RESUMO

Luminal breast cancer (LBC) driven by dysregulated estrogen receptor-alpha (ERα) signaling accounts for 70% of the breast cancer cases diagnosed. Although endocrine therapy (ET) is effective against LBC, about one-third of these patients fail to respond to therapy owing to acquired or inherent resistance mechanisms. Aberrant signaling via ERα, oncogenes, growth factor receptors, and mutations in tumor suppressors such as p53 impinge on downstream regulators such as AMPK and mTOR. While both AMPK and mTOR have been reported to play important roles in determining sensitivity of LBC to ET, how the ERα-p53 crosstalk impinges on regulation of AMPK and mTOR, thereby influencing therapeutic efficacy remains unknown. Here, we have addressed this important issue using isogenic breast cancer cell lines, siRNA-mediated RNA knockdown, and different modes of drug treatments. Interaction of p53 with ERα and AMPK was determined by in situ proximity ligation assay (PLA), and endogenous gene transcripts were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR). Further, the effect of concurrent and sequential administration of Fulvestrant-Everolimus combination on colony formation was determined. The studies showed that in cells expressing wild type p53, as well as in cells devoid of p53, ERα represses AMPK, whereas in cells harboring mutant p53, repression of AMPK is sustained even in the absence of ERα. AMPK is a major negative regulator of mTOR, and to our knowledge, this is the first study on the contribution of AMPK-dependent regulation of mTOR by ERα. Furthermore, the studies revealed that independent of the p53 mutation status, combination of Fulvestrant and Everolimus may be a viable first line therapeutic strategy for potentially delaying resistance of ERα+/HER2- LBC to ET.

12.
Heliyon ; 7(2): e06116, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33644444

RESUMO

Standardization is an important measurement for ensuring the quality control of herbal drugs. It has become essential to develop reliable, specific and sensitive quality control methods. Ashwagandhadi lehyam is an important Ayurvedic formulation containing Withania somnifera L., as one of the prime ingredient of formulation. The present study was undertaken to develop standardization parameters for Ashwagandhadi lehyam. Evaluation of various standardization parameters like organoleptic characters, Physico-chemical evaluation, HPTLC finger print profiling along with dominant bioactive markers and estimation of bioactive markers Withaferin-A by HPLC. The Rf value of Withaferin-A 0.35 and Withanolide-A 0.45 is in formulation and reference standards were found comparable under UV light at 254 nm and 540 nm. The HPLC chromatogram of Ashwagandhadi lehyam and standard Withaferin-A showed at Rt of 5.015 and 5.050 min. The percentage of Withaferin-A was 0.092% present in Ashwagandhadi lehyam formulation. Bioactive markers are characteristic to the ingredients or botanicals to identify the presence of ingredients in formulation easily. The presence of bioactive markers is possible and its verification through the HPTLC fingerprint profile and quantification of biomarker by HPLC are the best ways to identify evaluate the quality of the finished formulation in the course of development of a standardization protocol for quality control of Ayurvedic formulation.

13.
Nanotechnology ; 31(41): 415706, 2020 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-32570232

RESUMO

Chemical vapour deposition (CVD) is one of the most promising methods to synthesize monolayers of 2D materials like transition metal dichalcogenides (TMDs) over a large area with high film quality. Among many parameters that determine the growth of 2D materials, flow of precursor near the surface is one of the most sensitive conditions. In this study, we show how subtle changes in the flow near the substrate surface can affect the quality and coverage of the MoS2 monolayer. We fine tune the flow of the carrier gas near the substrate under two extreme conditions to grow large area and clean monolayer. In the first study, we grew several centimetres long continuous monolayer under the condition, which generally produces monolayers of few tens of micrometres in size without tuning the flow on the substrate surface. In the second case, we got monolayer MoS2 under the conditions meant for the formation of bulk MoS2.We achieved this by placing blockades on the substrate surface which helped in modifying the flow near them. Through simulation, we showed how the flow is affected near these blockades and used it as a guiding rule to grow patterned continuous MoS2 monolayers. Detailed electrical and optical measurements were done to determine the quality of the as-grown samples. Our studies provide a way to obtain clean, large area monolayer of desired pattern by tuning the flow of precursor on the vicinity of the substrate surface even when the growth conditions in CVD are far from optimum.

14.
J Natl Cancer Inst ; 111(11): 1202-1215, 2019 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-30990221

RESUMO

BACKGROUND: Anti-tumorigenic vs pro-tumorigenic roles of estrogen receptor-beta (ESR2) in breast cancer remain unsettled. We investigated the potential of TP53 status to be a determinant of the bi-faceted role of ESR2 and associated therapeutic implications for triple negative breast cancer (TNBC). METHODS: ESR2-TP53 interaction was analyzed with multiple assays including the in situ proximity ligation assay. Transcriptional effects on TP53-target genes and cell proliferation in response to knocking down or overexpressing ESR2 were determined. Patient survival according to ESR2 expression levels and TP53 mutation status was analyzed in the basal-like TNBC subgroup in the Molecular Taxonomy of Breast Cancer International Consortium (n = 308) and Roswell Park Comprehensive Cancer Center (n = 46) patient cohorts by univariate Cox regression and log-rank test. All statistical tests are two-sided. RESULTS: ESR2 interaction with wild-type and mutant TP53 caused pro-proliferative and anti-proliferative effects, respectively. Depleting ESR2 in cells expressing wild-type TP53 resulted in increased expression of TP53-target genes CDKN1A (control group mean [SD] = 1 [0.13] vs ESR2 depletion group mean [SD] = 2.08 [0.24], P = .003) and BBC3 (control group mean [SD] = 1 [0.06] vs ESR2 depleted group mean [SD] = 1.92 [0.25], P = .003); however, expression of CDKN1A (control group mean [SD] = 1 [0.21] vs ESR2 depleted group mean [SD] = 0.56 [0.12], P = .02) and BBC3 (control group mean [SD] = 1 [0.03] vs ESR2 depleted group mean [SD] = 0.55 [0.09], P = .008) was decreased in cells expressing mutant TP53. Overexpressing ESR2 had opposite effects. Tamoxifen increased ESR2-mutant TP53 interaction, leading to reactivation of TP73 and apoptosis. High levels of ESR2 expression in mutant TP53-expressing basal-like tumors is associated with better prognosis (Molecular Taxonomy of Breast Cancer International Consortium cohort: log-rank P = .001; hazard ratio = 0.26, 95% confidence interval = 0.08 to 0.84, univariate Cox P = .02). CONCLUSIONS: TP53 status is a determinant of the functional duality of ESR2. Our study suggests that ESR2-mutant TP53 combination prognosticates survival in TNBC revealing a novel strategy to stratify TNBC for therapeutic intervention potentially by repurposing tamoxifen.


Assuntos
Biomarcadores Tumorais/metabolismo , Carcinogênese/patologia , Receptor beta de Estrogênio/metabolismo , Proteínas Mutantes/metabolismo , Mutação , Neoplasias de Mama Triplo Negativas/patologia , Proteína Supressora de Tumor p53/metabolismo , Biomarcadores Tumorais/genética , Carcinogênese/genética , Carcinogênese/metabolismo , Proliferação de Células , Estudos de Coortes , Receptor beta de Estrogênio/genética , Feminino , Humanos , Proteínas Mutantes/genética , Prognóstico , Taxa de Sobrevida , Neoplasias de Mama Triplo Negativas/genética , Neoplasias de Mama Triplo Negativas/metabolismo , Células Tumorais Cultivadas , Proteína Supressora de Tumor p53/genética
15.
Cells ; 8(2)2019 01 26.
Artigo em Inglês | MEDLINE | ID: mdl-30691108

RESUMO

Current standard-of-care (SOC) therapy for breast cancer includes targeted therapies such as endocrine therapy for estrogen receptor-alpha (ERα) positive; anti-HER2 monoclonal antibodies for human epidermal growth factor receptor-2 (HER2)-enriched; and general chemotherapy for triple negative breast cancer (TNBC) subtypes. These therapies frequently fail due to acquired or inherent resistance. Altered metabolism has been recognized as one of the major mechanisms underlying therapeutic resistance. There are several cues that dictate metabolic reprogramming that also account for the tumors' metabolic plasticity. For metabolic therapy to be efficacious there is a need to understand the metabolic underpinnings of the different subtypes of breast cancer as well as the role the SOC treatments play in targeting the metabolic phenotype. Understanding the mechanism will allow us to identify potential therapeutic vulnerabilities. There are some very interesting questions being tackled by researchers today as they pertain to altered metabolism in breast cancer. What are the metabolic differences between the different subtypes of breast cancer? Do cancer cells have a metabolic pathway preference based on the site and stage of metastasis? How do the cell-intrinsic and -extrinsic cues dictate the metabolic phenotype? How do the nucleus and mitochondria coordinately regulate metabolism? How does sensitivity or resistance to SOC affect metabolic reprogramming and vice-versa? This review addresses these issues along with the latest updates in the field of breast cancer metabolism.


Assuntos
Neoplasias da Mama/metabolismo , Neoplasias da Mama/terapia , Neoplasias da Mama/patologia , Feminino , Humanos , Modelos Biológicos , Metástase Neoplásica , Microambiente Tumoral
17.
Elife ; 62017 08 18.
Artigo em Inglês | MEDLINE | ID: mdl-28826481

RESUMO

Standard treatment for metastatic prostate cancer (CaP) prevents ligand-activation of androgen receptor (AR). Despite initial remission, CaP progresses while relying on AR. AR transcriptional output controls CaP behavior and is an alternative therapeutic target, but its molecular regulation is poorly understood. Here, we show that action of activated AR partitions into fractions that are controlled preferentially by different coregulators. In a 452-AR-target gene panel, each of 18 clinically relevant coregulators mediates androgen-responsiveness of 0-57% genes and acts as a coactivator or corepressor in a gene-specific manner. Selectivity in coregulator-dependent AR action is reflected in differential AR binding site composition and involvement with CaP biology and progression. Isolation of a novel transcriptional mechanism in which WDR77 unites the actions of AR and p53, the major genomic drivers of lethal CaP, to control cell cycle progression provides proof-of-principle for treatment via selective interference with AR action by exploiting AR dependence on coregulators.


Assuntos
Regulação da Expressão Gênica , Neoplasias da Próstata/patologia , Receptores Androgênicos/metabolismo , Linhagem Celular Tumoral , Humanos , Masculino , Fatores de Transcrição/metabolismo , Transcrição Gênica , Proteína Supressora de Tumor p53/metabolismo
18.
J Am Soc Nephrol ; 27(11): 3285-3290, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27036737

RESUMO

In glomerular disease, podocyte injury results in a dramatic change in cell morphology known as foot process effacement. Remodeling of the actin cytoskeleton through the activity of small GTPases was identified as a key mechanism in effacement, with increased membrane activity and motility in vitro However, whether podocytes are stationary or actively moving cells in vivo remains debated. Using intravital and kidney slice two-photon imaging of the three-dimensional structure of mouse podocytes, we found that uninjured podocytes remained nonmotile and maintained a canopy-shaped structure over time. On expression of constitutively active Rac1, however, podocytes changed shape by retracting processes and clearly exhibited domains of increased membrane activity. Constitutive activation of Rac1 also led to podocyte detachment from the glomerular basement membrane, and we detected detached podocytes crawling on the surface of the tubular epithelium and occasionally, in contact with peritubular capillaries. Podocyte membrane activity also increased in the inflammatory environment of immune complex-mediated GN. Our results provide evidence that podocytes transition from a static to a dynamic state in vivo, shedding new light on mechanisms in foot process effacement.


Assuntos
Membrana Celular/fisiologia , Podócitos/fisiologia , Podócitos/ultraestrutura , Animais , Microscopia Intravital , Rim/citologia , Camundongos , Microscopia de Fluorescência por Excitação Multifotônica
19.
Oncotarget ; 7(13): 16049-69, 2016 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-26909605

RESUMO

MDM2 and MDM4 are heterodimeric, non-redundant oncoproteins that potently inhibit the p53 tumor suppressor protein. MDM2 and MDM4 also enhance the tumorigenicity of breast cancer cells in in vitro and in vivo models and are overexpressed in primary human breast cancers. Prior studies have characterized Estrogen Receptor Alpha (ERα/ESR1) as a regulator of MDM2 expression and an MDM2- and p53-interacting protein. However, similar crosstalk between ERα and MDM4 has not been investigated. Moreover, signaling pathways that mediate the overexpression of MDM4 in human breast cancer remain to be elucidated. Using the Cancer Genome Atlas (TCGA) breast invasive carcinoma patient cohort, we have analyzed correlations between ERα status and MDM4 and MDM2 expression in primary, treatment-naïve, invasive breast carcinoma samples. We report that the expression of MDM4 and MDM2 is elevated in primary human breast cancers of luminal A/B subtypes and associates with ERα-positive disease, independently of p53 mutation status. Furthermore, in cell culture models, ERα positively regulates MDM4 and MDM2 expression via p53-independent mechanisms, and these effects can be blocked by the clinically-relevant endocrine therapies fulvestrant and tamoxifen. Additionally, ERα also positively regulates p53 expression. Lastly, we report that endogenous MDM4 negatively regulates ERα expression and forms a protein complex with ERα in breast cancer cell lines and primary human breast tumor tissue. This suggests direct signaling crosstalk and negative feedback loops between ERα and MDM4 expression in breast cancer cells. Collectively, these novel findings implicate ERα as a central component of the p53-MDM2-MDM4 signaling axis in human breast cancer.


Assuntos
Neoplasias da Mama/metabolismo , Carcinoma Ductal de Mama/metabolismo , Receptor alfa de Estrogênio/metabolismo , Regulação Neoplásica da Expressão Gênica/fisiologia , Proteínas Nucleares/biossíntese , Proteínas Proto-Oncogênicas c-mdm2/biossíntese , Proteínas Proto-Oncogênicas/biossíntese , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Carcinoma Ductal de Mama/genética , Carcinoma Ductal de Mama/patologia , Proteínas de Ciclo Celular , Receptor alfa de Estrogênio/genética , Feminino , Perfilação da Expressão Gênica , Humanos , Proteínas Nucleares/genética , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas c-mdm2/genética , Receptor Cross-Talk/fisiologia , Transcriptoma , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo , Regulação para Cima
20.
Cell ; 160(6): 1061-71, 2015 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-25728668

RESUMO

Triggering receptor expressed on myeloid cells 2 (TREM2) is a microglial surface receptor that triggers intracellular protein tyrosine phosphorylation. Recent genome-wide association studies have shown that a rare R47H mutation of TREM2 correlates with a substantial increase in the risk of developing Alzheimer's disease (AD). To address the basis for this genetic association, we studied TREM2 deficiency in the 5XFAD mouse model of AD. We found that TREM2 deficiency and haploinsufficiency augment ß-amyloid (Aß) accumulation due to a dysfunctional response of microglia, which fail to cluster around Aß plaques and become apoptotic. We further demonstrate that TREM2 senses a broad array of anionic and zwitterionic lipids known to associate with fibrillar Aß in lipid membranes and to be exposed on the surface of damaged neurons. Remarkably, the R47H mutation impairs TREM2 detection of lipid ligands. Thus, TREM2 detects damage-associated lipid patterns associated with neurodegeneration, sustaining the microglial response to Aß accumulation.


Assuntos
Glicoproteínas de Membrana/metabolismo , Microglia/metabolismo , Receptores Imunológicos/metabolismo , Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/metabolismo , Animais , Sobrevivência Celular , Modelos Animais de Doenças , Humanos , Glicoproteínas de Membrana/genética , Camundongos , Microglia/citologia , Mutação , Receptores Imunológicos/genética
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