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1.
Eur J Pharm Biopharm ; 142: 195-203, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31228557

RESUMO

We recently constructed a multicellular spheroid model of pancreatic tumor based on a triple co-culture of cancer cells, fibroblasts and endothelial cells and characterized by the presence of fibronectin, an important component of the tumor extracellular matrix. By combining cancer cells and stromal components, this model recreates in vitro the three-dimensional (3D) architecture of solid tumors. In this study, we used these hetero-type spheroids as a tool to assess the penetration of doxorubicin (used as a model drug) through the whole tumor mass either in a free form or loaded into polymer nanoparticles (NPs), and we investigated whether microscopy images, acquired by Confocal Laser Scanning Microscopy (CLSM) and Light Sheet Fluorescence Microscopy (LSFM), would be best to provide reliable information on this process. Results clearly demonstrated that CLSM was not suitable to accurately monitor the diffusion of small molecules such as the doxorubicin. Indeed, it only allowed to scan a layer of 100 µm depth and no information on deeper layers could be available because of a progressive loss of the fluorescence signal. On the contrary, a complete 3D tomography of the hetero-type multicellular tumor spheroids (MCTS) was obtained by LSFM and multi-view image fusion which revealed that the fluorescent molecule was able to reach the core of spheroids as large as 1 mm in diameter. However, no doxorubicin-loaded polymer nanoparticles were detected in the spheroids, highlighting the challenge of nanomedicine delivery through biological barriers. Overall, the combination of hetero-type MCTS and LSFM allowed to carry out a highly informative microscopic assessment and represents a suitable approach to precisely follow up the drug penetration in tumors. Accordingly, it could provide useful support in the preclinical investigation and optimization of nanoscale systems for drug delivery to solid tumors.

2.
Hum Mol Genet ; 28(16): 2720-2737, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-31042281

RESUMO

Mutations in genes encoding components of the intraflagellar transport (IFT) complexes have previously been associated with a spectrum of diseases collectively termed ciliopathies. Ciliopathies relate to defects in the formation or function of the cilium, a sensory or motile organelle present on the surface of most cell types. IFT52 is a key component of the IFT-B complex and ensures the interaction of the two subcomplexes, IFT-B1 and IFT-B2. Here, we report novel IFT52 biallelic mutations in cases with a short-rib thoracic dysplasia (SRTD) or a congenital anomaly of kidney and urinary tract (CAKUT). Combining in vitro and in vivo studies in zebrafish, we showed that SRTD-associated missense mutation impairs IFT-B complex assembly and IFT-B2 ciliary localization, resulting in decreased cilia length. In comparison, CAKUT-associated missense mutation has a mild pathogenicity, thus explaining the lack of skeletal defects in CAKUT case. In parallel, we demonstrated that the previously reported homozygous nonsense IFT52 mutation associated with Sensenbrenner syndrome [Girisha et al. (2016) A homozygous nonsense variant in IFT52 is associated with a human skeletal ciliopathy. Clin. Genet., 90, 536-539] leads to exon skipping and results in a partially functional protein. Finally, our work uncovered a novel role for IFT52 in microtubule network regulation. We showed that IFT52 interacts and partially co-localized with centrin at the distal end of centrioles where it is involved in its recruitment and/or maintenance. Alteration of this function likely contributes to centriole splitting observed in Ift52-/- cells. Altogether, our findings allow a better comprehensive genotype-phenotype correlation among IFT52-related cases and revealed a novel, extra-ciliary role for IFT52, i.e. disruption may contribute to pathophysiological mechanisms.

3.
Nat Commun ; 9(1): 2279, 2018 06 11.
Artigo em Inglês | MEDLINE | ID: mdl-29891944

RESUMO

Multiciliated ependymal cells line all brain cavities. The beating of their motile cilia contributes to the flow of cerebrospinal fluid, which is required for brain homoeostasis and functions. Motile cilia, nucleated from centrioles, persist once formed and withstand the forces produced by the external fluid flow and by their own cilia beating. Here, we show that a dense actin network around the centrioles is induced by cilia beating, as shown by the disorganisation of the actin network upon impairment of cilia motility. Moreover, disruption of the actin network, or specifically of the apical actin network, causes motile cilia and their centrioles to detach from the apical surface of ependymal cell. In conclusion, cilia beating controls the apical actin network around centrioles; the mechanical resistance of this actin network contributes, in turn, to centriole stability.

4.
Am J Hum Genet ; 102(2): 266-277, 2018 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-29395073

RESUMO

Neurodegeneration with brain iron accumulation (NBIA) is a genetically heterogeneous condition characterized by progressive dystonia with iron accumulation in the basal ganglia. How NBIA-associated mutations trigger iron overload remains poorly understood. After studying fibroblast cell lines from subjects carrying both known and unreported biallelic mutations in CRAT and REPS1, we ascribe iron overload to the abnormal recycling of transferrin receptor (TfR1) and the reduction of TfR1 palmitoylation in NBIA. Moreover, we describe palmitoylation as a hitherto unreported level of post-translational TfR1 regulation. A widely used antimalarial agent, artesunate, rescued abnormal TfR1 palmitoylation in cultured fibroblasts of NBIA subjects. These observations suggest therapeutic strategies aimed at targeting impaired TfR1 recycling and palmitoylation in NBIA.

5.
Hum Mol Genet ; 27(1): 1-13, 2018 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-29040558

RESUMO

Fibroblast growth factor receptor 3 (FGFR3) gain-of-function mutations cause dwarfisms, including achondroplasia (ACH) and thanatophoric dysplasia (TD). The constitutive activation of FGFR3 disrupts the normal process of skeletal growth. Bone-growth anomalies have been identified in skeletal ciliopathies, in which primary cilia (PC) function is disrupted. In human ACH and TD, the impact of FGFR3 mutations on PC in growth plate cartilage remains unknown. Here we showed that in chondrocytes from human (ACH, TD) and mouse Fgfr3Y367C/+ cartilage, the constitutively active FGFR3 perturbed PC length and the sorting and trafficking of intraflagellar transport (IFT) 20 to the PC. We demonstrated that inhibiting FGFR3 with FGFR inhibitor, PD173074, rescued both PC length and IFT20 trafficking. We also studied the impact of rapamycin, an inhibitor of mammalian target of rapamycin (mTOR) pathway. Interestingly, mTOR inhibition also rescued PC length and IFT20 trafficking. Together, we provide evidence that the growth plate defects ascribed to FGFR3-related dwarfisms are potentially due to loss of PC function, and these dwarfisms may represent a novel type of skeletal disorders with defective ciliogenesis.

6.
Hum Mol Genet ; 27(2): 266-282, 2018 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-29121203

RESUMO

A child presenting with Mainzer-Saldino syndrome (MZSDS), characterized by renal, retinal and skeletal involvements, was also diagnosed with lung infections and airway ciliary dyskinesia. These manifestations suggested dysfunction of both primary and motile cilia, respectively. Targeted exome sequencing identified biallelic mutations in WDR19, encoding an IFT-A subunit previously associated with MZSDS-related chondrodysplasia, Jeune asphyxiating thoracic dysplasia and cranioectodermal dysplasia, linked to primary cilia dysfunction, and in TEKT1 which encodes tektin-1 an uncharacterized member of the tektin family, mutations of which may cause ciliary dyskinesia. Tektin-1 localizes at the centrosome in cycling cells, at basal bodies of both primary and motile cilia and to the axoneme of motile cilia in airway cells. The identified mutations impaired these localizations. In addition, airway cells from the affected individual showed severe motility defects without major ultrastructural changes. Knockdown of tekt1 in zebrafish resulted in phenotypes consistent with a function for tektin-1 in ciliary motility, which was confirmed by live imaging. Finally, experiments in the zebrafish also revealed a synergistic effect of tekt1 and wdr19. Altogether, our data show genetic interactions between WDR19 and TEKT1 likely contributing to the overall clinical phenotype observed in the affected individual and provide strong evidence for TEKT1 as a new candidate gene for primary ciliary dyskinesia.

7.
Am J Hum Genet ; 101(6): 1006-1012, 2017 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-29198720

RESUMO

Leber congenital amaurosis (LCA) is a neurodegenerative disease of photoreceptor cells that causes blindness within the first year of life. It occasionally occurs in syndromic metabolic diseases and plurisystemic ciliopathies. Using exome sequencing in a multiplex family and three simplex case subjects with an atypical association of LCA with early-onset hearing loss, we identified two heterozygous mutations affecting Arg391 in ß-tubulin 4B isotype-encoding (TUBB4B). Inspection of the atomic structure of the microtubule (MT) protofilament reveals that the ß-tubulin Arg391 residue contributes to a binding pocket that interacts with α-tubulin contained in the longitudinally adjacent αß-heterodimer, consistent with a role in maintaining MT stability. Functional analysis in cultured cells overexpressing FLAG-tagged wild-type or mutant TUBB4B as well as in primary skin-derived fibroblasts showed that the mutant TUBB4B is able to fold, form αß-heterodimers, and co-assemble into the endogenous MT lattice. However, the dynamics of growing MTs were consistently altered, showing that the mutations have a significant dampening impact on normal MT growth. Our findings provide a link between sensorineural disease and anomalies in MT behavior and describe a syndromic LCA unrelated to ciliary dysfunction.


Assuntos
Amaurose Congênita de Leber/genética , Microtúbulos/genética , Tubulina (Proteína)/genética , Adulto , Sítios de Ligação/genética , Células Cultivadas , Criança , Análise Mutacional de DNA , Feminino , Humanos , Masculino , Microtúbulos/metabolismo , Pessoa de Meia-Idade , Mutação de Sentido Incorreto/genética , Células Fotorreceptoras/metabolismo , Tubulina (Proteína)/metabolismo , Sequenciamento Completo do Exoma
8.
Nat Commun ; 8(1): 1640, 2017 11 21.
Artigo em Inglês | MEDLINE | ID: mdl-29158474

RESUMO

Dendritic cells (DC) have the unique ability to present exogenous antigens via the major histocompatibility complex class I pathway to stimulate naive CD8+ T cells. In DCs with a non-functional mutation in Unc93b1 (3d mutation), endosomal acidification, phagosomal maturation, antigen degradation, antigen export to the cytosol and the function of the store-operated-Ca2+-entry regulator STIM1 are impaired. These defects result in compromised antigen cross-presentation and anti-tumor responses in 3d-mutated mice. Here, we show that UNC93B1 interacts with the calcium sensor STIM1 in the endoplasmic reticulum, a critical step for STIM1 oligomerization and activation. Expression of a constitutively active STIM1 mutant, which no longer binds UNC93B1, restores antigen degradation and cross-presentation in 3d-mutated DCs. Furthermore, ablation of STIM1 in mouse and human cells leads to a decrease in cross-presentation. Our data indicate that the UNC93B1 and STIM1 cooperation is important for calcium flux and antigen cross-presentation in DCs.


Assuntos
Apresentação do Antígeno , Cálcio/metabolismo , Células Dendríticas/imunologia , Proteínas de Membrana Transportadoras/metabolismo , Molécula 1 de Interação Estromal/metabolismo , Animais , Antígenos/imunologia , Antígenos/metabolismo , Células Cultivadas , Apresentação Cruzada , Células Dendríticas/metabolismo , Retículo Endoplasmático/metabolismo , Feminino , Humanos , Masculino , Proteínas de Membrana Transportadoras/genética , Proteínas de Membrana Transportadoras/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Ligação Proteica , Molécula 1 de Interação Estromal/genética , Molécula 1 de Interação Estromal/imunologia
9.
Brain ; 140(10): 2597-2609, 2017 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-28969387

RESUMO

Microlissencephaly is a rare brain malformation characterized by congenital microcephaly and lissencephaly. Microlissencephaly is suspected to result from abnormalities in the proliferation or survival of neural progenitors. Despite the recent identification of six genes involved in microlissencephaly, the pathophysiological basis of this condition remains poorly understood. We performed trio-based whole exome sequencing in seven subjects from five non-consanguineous families who presented with either microcephaly or microlissencephaly. This led to the identification of compound heterozygous mutations in WDR81, a gene previously associated with cerebellar ataxia, intellectual disability and quadrupedal locomotion. Patient phenotypes ranged from severe microcephaly with extremely reduced gyration with pontocerebellar hypoplasia to moderate microcephaly with cerebellar atrophy. In patient fibroblast cells, WDR81 mutations were associated with increased mitotic index and delayed prometaphase/metaphase transition. Similarly, in vivo, we showed that knockdown of the WDR81 orthologue in Drosophila led to increased mitotic index of neural stem cells with delayed mitotic progression. In summary, we highlight the broad phenotypic spectrum of WDR81-related brain malformations, which include microcephaly with moderate to extremely reduced gyration and cerebellar anomalies. Our results suggest that WDR81 might have a role in mitosis that is conserved between Drosophila and humans.


Assuntos
Fibroblastos/citologia , Microcefalia/genética , Microcefalia/patologia , Mitose/genética , Mutação/genética , Proteínas do Tecido Nervoso/genética , Células-Tronco Neurais/citologia , Animais , Animais Geneticamente Modificados , Encéfalo/diagnóstico por imagem , Encéfalo/patologia , Células Cultivadas , Pré-Escolar , Drosophila , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Feminino , Fibroblastos/patologia , Regulação da Expressão Gênica/genética , Humanos , Antígeno Ki-67/metabolismo , Masculino , Microcefalia/diagnóstico por imagem , Células-Tronco Neurais/patologia , Interferência de RNA/fisiologia , Adulto Jovem
10.
Nat Immunol ; 18(5): 509-518, 2017 05.
Artigo em Inglês | MEDLINE | ID: mdl-28319098

RESUMO

The retention of intracellular Toll-like receptors (TLRs) in the endoplasmic reticulum prevents their activation under basal conditions. TLR9 is activated by sensing ligands in specific endosomal-lysosomal compartments. Here we identified IRAP+ endosomes as major cellular compartments for the early steps of TLR9 activation in dendritic cells (DCs). Both TLR9 and its ligand, the dinucleotide CpG, were present as cargo in IRAP+ endosomes. In the absence of the aminopeptidase IRAP, the trafficking of CpG and TLR9 to lysosomes and signaling via TLR9 were enhanced in DCs and in mice following bacterial infection. IRAP stabilized CpG-containing endosomes by interacting with the actin-nucleation factor FHOD4, which slowed the trafficking of TLR9 toward lysosomes. Thus, endosomal retention of TLR9 via the interaction of IRAP with the actin cytoskeleton is a mechanism that prevents hyper-activation of TLR9 in DCs.


Assuntos
Cistinil Aminopeptidase/metabolismo , Citoesqueleto/metabolismo , Células Dendríticas/fisiologia , Endossomos/metabolismo , Infecções por Pseudomonas/imunologia , Pseudomonas aeruginosa/imunologia , Receptor Toll-Like 9/metabolismo , Animais , Células Cultivadas , Ilhas de CpG/genética , Cistinil Aminopeptidase/genética , Células Dendríticas/microbiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mutação/genética , Oligodesoxirribonucleotídeos/imunologia , Ligação Proteica , Transdução de Sinais
11.
Blood ; 127(17): 2113-21, 2016 04 28.
Artigo em Inglês | MEDLINE | ID: mdl-26864340

RESUMO

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening hyperinflammatory disease. Inherited forms of HLH are caused by biallelic mutations in several effectors of granule-dependent lymphocyte-mediated cytotoxicity. A small proportion of patients with a so-called "secondary" form of HLH, which develops in the aftermath of infection, autoimmunity, or cancer, carry a monoallelic mutation in one or more HLH-associated genes. Although this observation suggests that HLH may have a polygenic mode of inheritance, the latter is very difficult to prove in humans. In order to determine whether the accumulation of partial genetic defects in lymphocyte-mediated cytotoxicity can contribute to the development of HLH, we generated mice that were doubly or triply heterozygous for mutations in HLH-associated genes, those coding for perforin, Rab27a, and syntaxin-11. We found that the accumulation of monoallelic mutations did indeed increase the risk of developing HLH immunopathology after lymphocytic choriomeningitis virus infection. In mechanistic terms, the accumulation of heterozygous mutations in the two degranulation genes Rab27a and syntaxin-11, impaired the dynamics and secretion of cytotoxic granules at the immune synapse of T lymphocytes. In addition, the accumulation of heterozygous mutations within the three genes impaired natural killer lymphocyte cytotoxicity in vivo. The genetic defects can be ranked in terms of the severity of the resulting HLH manifestations. Our results form the basis of a polygenic model of the occurrence of secondary HLH.


Assuntos
Linfo-Histiocitose Hemofagocítica/genética , Herança Multifatorial , Proteínas Citotóxicas Formadoras de Poros/genética , Proteínas Qa-SNARE/genética , Proteínas rab de Ligação ao GTP/genética , Animais , Degranulação Celular/genética , Cruzamentos Genéticos , Citotoxicidade Imunológica/genética , Dosagem de Genes , Predisposição Genética para Doença , Heterozigoto , Sinapses Imunológicas/imunologia , Células Matadoras Naturais/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Modelos Animais , Mutação , Proteínas Citotóxicas Formadoras de Poros/fisiologia , Proteínas Qa-SNARE/fisiologia , Organismos Livres de Patógenos Específicos , Linfócitos T Citotóxicos/imunologia , Proteínas rab de Ligação ao GTP/fisiologia , Proteínas rab27 de Ligação ao GTP
12.
Nat Commun ; 6: 8666, 2015 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-26487268

RESUMO

Ciliopathies are a large group of clinically and genetically heterogeneous disorders caused by defects in primary cilia. Here we identified mutations in TRAF3IP1 (TNF Receptor-Associated Factor Interacting Protein 1) in eight patients from five families with nephronophthisis (NPH) and retinal degeneration, two of the most common manifestations of ciliopathies. TRAF3IP1 encodes IFT54, a subunit of the IFT-B complex required for ciliogenesis. The identified mutations result in mild ciliary defects in patients but also reveal an unexpected role of IFT54 as a negative regulator of microtubule stability via MAP4 (microtubule-associated protein 4). Microtubule defects are associated with altered epithelialization/polarity in renal cells and with pronephric cysts and microphthalmia in zebrafish embryos. Our findings highlight the regulation of cytoplasmic microtubule dynamics as a role of the IFT54 protein beyond the cilium, contributing to the development of NPH-related ciliopathies.


Assuntos
Proteínas de Transporte/genética , Doenças Renais Císticas/genética , Proteínas Associadas aos Microtúbulos/genética , Proteínas Associadas aos Microtúbulos/metabolismo , Microtúbulos/metabolismo , Mutação , Degeneração Retiniana/genética , Proteínas de Peixe-Zebra/genética , Animais , Western Blotting , Proteínas de Transporte/metabolismo , Polaridade Celular/genética , Dicroísmo Circular , Embrião não Mamífero , Feminino , Imunofluorescência , Técnicas de Inativação de Genes , Células HEK293 , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Imunoprecipitação , Doenças Renais Císticas/metabolismo , Masculino , Microftalmia/genética , Linhagem , Degeneração Retiniana/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Peixe-Zebra , Proteínas de Peixe-Zebra/metabolismo
13.
J Med Genet ; 52(10): 657-65, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26275418

RESUMO

BACKGROUND: Bidirectional intraflagellar transport (IFT) consists of two major protein complexes, IFT-A and IFT-B. In contrast to the IFT-B complex, all components of IFT-A have recently been linked to human ciliopathies when defective. We therefore hypothesised that mutations in additional IFT-B encoding genes can be found in patients with multisystemic ciliopathies. METHODS: We screened 1628 individuals with reno-ocular ciliopathies by targeted next-generation sequencing of ciliary candidate genes, including all IFT-B encoding genes. RESULTS: Consequently, we identified a homozygous mutation in IFT81 affecting an obligatory donor splice site in an individual with nephronophthisis and polydactyly. Further, we detected a loss-of-stop mutation with extension of the deduced protein by 10 amino acids in an individual with neuronal ceroid lipofuscinosis-1. This proband presented with retinal dystrophy and brain lesions including cerebellar atrophy, a phenotype to which the IFT81 variant might contribute. Cultured fibroblasts of this latter affected individual showed a significant decrease in ciliated cell abundance compared with controls and increased expression of the transcription factor GLI2 suggesting deranged sonic hedgehog signalling. CONCLUSIONS: This work describes identification of mutations of IFT81 in individuals with symptoms consistent with the clinical spectrum of ciliopathies. It might represent the rare case of a core IFT-B complex protein found associated with human disease. Our data further suggest that defects in the IFT-B core are an exceedingly rare finding, probably due to its indispensable role for ciliary assembly in development.


Assuntos
Cílios/genética , Cílios/patologia , Olho/patologia , Rim/patologia , Proteínas Musculares/genética , Humanos , Mutação , Análise de Sequência de DNA
14.
Am J Hum Genet ; 97(2): 311-8, 2015 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-26166481

RESUMO

KIAA0586, the human ortholog of chicken TALPID3, is a centrosomal protein that is essential for primary ciliogenesis. Its disruption in animal models causes defects attributed to abnormal hedgehog signaling; these defects include polydactyly and abnormal dorsoventral patterning of the neural tube. Here, we report homozygous mutations of KIAA0586 in four families affected by lethal ciliopathies ranging from a hydrolethalus phenotype to short-rib polydactyly. We show defective ciliogenesis, as well as abnormal response to SHH-signaling activation in cells derived from affected individuals, consistent with a role of KIAA0586 in primary cilia biogenesis. Whereas centriolar maturation seemed unaffected in mutant cells, we observed an abnormal extended pattern of CEP290, a centriolar satellite protein previously associated with ciliopathies. Our data show the crucial role of KIAA0586 in human primary ciliogenesis and subsequent abnormal hedgehog signaling through abnormal GLI3 processing. Our results thus establish that KIAA0586 mutations cause lethal ciliopathies.


Assuntos
Proteínas de Ciclo Celular/genética , Transtornos da Motilidade Ciliar/genética , Códon sem Sentido/genética , Deformidades Congênitas da Mão/genética , Cardiopatias Congênitas/genética , Hidrocefalia/genética , Fenótipo , Síndrome de Costela Curta e Polidactilia/genética , Sequência de Bases , Transtornos da Motilidade Ciliar/patologia , Europa Oriental , Evolução Fatal , Efeito Fundador , Humanos , Funções Verossimilhança , Dados de Sequência Molecular , Linhagem , Análise de Sequência de DNA
15.
Sci Transl Med ; 7(281): 281ra42, 2015 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-25834108

RESUMO

Granulocyte colony-stimulating factor (G-CSF) is routinely used to collect peripheral blood stem cells (PBSCs) from healthy donors for allogeneic hematopoietic stem cell transplantation (allo-HSCT). We show that, in both humans and mice, G-CSF mobilizes a subset of CD34(+) cells with mature monocyte features. These cells, which are phenotypically and functionally conserved in mice and humans, are transcriptionally distinct from myeloid and monocytic precursors but similar to mature monocytes and endowed with immunosuppressive properties. In response to interferon-γ released by activated T cells, these cells produce nitric oxide, which induces allogeneic T cell death both in vitro and in vivo. These apoptotic T cells are engulfed by macrophages that release transforming growth factor-ß and promote regulatory T cell expansion. Indeed, the fraction of CD34(+) monocytes in peripheral blood CD34(+) cells inversely correlates with the incidence of acute graft-versus-host disease (GVHD) in humans. Therefore, G-CSF-mobilized cells are an attractive candidate population to be expanded ex vivo for cellular therapy against GVHD.


Assuntos
Antígenos CD34/metabolismo , Doença Enxerto-Hospedeiro/imunologia , Fator Estimulador de Colônias de Granulócitos/farmacologia , Mobilização de Células-Tronco Hematopoéticas , Monócitos/metabolismo , Animais , Apoptose/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Humanos , Tolerância Imunológica/efeitos dos fármacos , Imunossupressão , Interferon gama/farmacologia , Ativação Linfocitária/efeitos dos fármacos , Ativação Linfocitária/imunologia , Camundongos , Monócitos/efeitos dos fármacos , Óxido Nítrico/biossíntese , Óxido Nítrico Sintase Tipo II/metabolismo , Linfócitos T Reguladores/citologia , Linfócitos T Reguladores/efeitos dos fármacos , Transplante Homólogo
16.
PLoS One ; 9(9): e108202, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25259951

RESUMO

Regulation of cell cycle in beta cells is poorly understood, especially in humans. We exploited here the recently described human pancreatic beta cell line EndoC-ßH2 to set up experimental systems for cell cycle studies. We derived 2 populations from EndoC-ßH2 cells that stably harbor the 2 genes encoding the Fucci fluorescent indicators of cell cycle, either from two vectors, or from a unique bicistronic vector. In proliferating non-synchronized cells, the 2 Fucci indicators revealed cells in the expected phases of cell cycle, with orange and green cells being in G1 and S/G2/M cells, respectively, and allowed the sorting of cells in different substeps of G1. The Fucci indicators also faithfully red out alterations in human beta cell proliferative activity since a mitogen-rich medium decreased the proportion of orange cells and inflated the green population, while reciprocal changes were observed when cells were induced to cease proliferation and increased expression of some beta cell genes. In the last situation, acquisition of a more differentiated beta cell phenotype correlates with an increased intensity in orange fluorescence. Hence Fucci beta cell lines provide new tools to address important questions regarding human beta cell cycle and differentiation.


Assuntos
Ciclo Celular , Diferenciação Celular , Células Secretoras de Insulina/citologia , Células Secretoras de Insulina/fisiologia , Biomarcadores , Linhagem Celular , Linhagem Celular Transformada , Proliferação de Células , Expressão Gênica , Ordem dos Genes , Vetores Genéticos/genética , Humanos , Transgenes
17.
J Bacteriol ; 196(17): 3059-73, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24982303

RESUMO

The evolutionary success of bacteria depends greatly on their capacity to continually generate phenotypic diversity. Structured environments are particularly favorable for diversification because of attenuated clonal interference, which renders selective sweeps nearly impossible and enhances opportunities for adaptive radiation. We examined at the microscale level the emergence and the spatial and temporal dynamics of phenotypic diversity and their underlying causes in Escherichia coli colonies. An important dynamic heterogeneity in the growth, metabolic activity, morphology, gene expression patterns, stress response induction, and death patterns among cells within colonies was observed. Genetic analysis indicated that the phenotypic variation resulted mostly from mutations and that indole production, oxidative stress, and the RpoS-regulated general stress response played an important role in the generation of diversity. We observed the emergence and persistence of phenotypic variants within single colonies that exhibited variable fitness compared to the parental strain. Some variants showed improved capacity to produce biofilms, whereas others were able to use different nutrients or to tolerate antibiotics or oxidative stress. Taken together, our data show that bacterial colonies provide an ecological opportunity for the generation and maintenance of vast phenotypic diversity, which may increase the probability of population survival in unpredictable environments.


Assuntos
Adaptação Fisiológica/genética , Biodiversidade , Evolução Biológica , Escherichia coli/citologia , Escherichia coli/fisiologia , Regulação Bacteriana da Expressão Gênica/fisiologia , Escherichia coli/genética , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Aptidão Genética , Fenótipo , Fatores de Tempo
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