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1.
Development ; 147(12)2020 06 22.
Artigo em Inglês | MEDLINE | ID: mdl-32467237

RESUMO

Thymus function depends on the epithelial compartment of the thymic stroma. Cortical thymic epithelial cells (cTECs) regulate T cell lineage commitment and positive selection, while medullary (m) TECs impose central tolerance on the T cell repertoire. During thymus organogenesis, these functionally distinct sub-lineages are thought to arise from a common thymic epithelial progenitor cell (TEPC). However, the mechanisms controlling cTEC and mTEC production from the common TEPC are not understood. Here, we show that emergence of the earliest mTEC lineage-restricted progenitors requires active NOTCH signaling in progenitor TEC and that, once specified, further mTEC development is NOTCH independent. In addition, we demonstrate that persistent NOTCH activity favors maintenance of undifferentiated TEPCs at the expense of cTEC differentiation. Finally, we uncover a cross-regulatory relationship between NOTCH and FOXN1, a master regulator of TEC differentiation. These data establish NOTCH as a potent regulator of TEPC and mTEC fate during fetal thymus development, and are thus of high relevance to strategies aimed at generating/regenerating functional thymic tissue in vitro and in vivo.


Assuntos
Desenvolvimento Embrionário/genética , Receptores Notch/metabolismo , Timo/metabolismo , Animais , Diferenciação Celular , Linhagem da Célula , Células Epiteliais/citologia , Células Epiteliais/metabolismo , Feminino , Fatores de Transcrição Forkhead/deficiência , Fatores de Transcrição Forkhead/genética , Fatores de Transcrição Forkhead/metabolismo , Mutação com Ganho de Função , Regulação da Expressão Gênica no Desenvolvimento , Proteína de Ligação a Sequências Sinal de Recombinação J de Imunoglobina/deficiência , Proteína de Ligação a Sequências Sinal de Recombinação J de Imunoglobina/genética , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , NF-kappa B/metabolismo , Organogênese , Receptores Notch/genética , Transdução de Sinais , Células-Tronco/citologia , Células-Tronco/metabolismo , Timo/citologia , Timo/crescimento & desenvolvimento
2.
Sports Biomech ; : 1-12, 2021 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-33660588

RESUMO

Les Mills BODYPUMPTM is a resistance training group exercise class with a low load, high repetition format. Squat training in BODYPUMPTM has two key variables: depth and load. The study aim was to determine the effect of these parameters on the mean and peak EMG amplitude of vastus lateralis, gluteus maximus, biceps femoris and lateral gastrocnemius. Ten female BODYPUMPTM participants (age 41 ± 9 years, height 161.9 ± 3.8 cm, mass 67.7 ± 7.0 kg) performed 1 × 7 squats under four conditions, representing every combination of two depths (90° knee angle and 125° knee angle) and two loads (23% bodyweight and 38% bodyweight). The main effect of depth was significant for mean and peak activity of vastus lateralis and gluteus maximus, and peak activity of biceps femoris and lateral gastrocnemius. The main effect of load was significant for mean and peak activity of gluteus maximus and lateral gastrocnemius. There was no depth * load interaction. These data can be used to inform BODYPUMPTM programme design and amplify the training effect of participation in group exercise classes.

3.
Bioessays ; 30(7): 617-20, 2008 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-18536025

RESUMO

The origin of insulin-expressing beta-cells in the adult mammalian pancreas is controversial. During normal tissue turnover and following injury, beta-cells may be replaced by duplication of existing beta-cells.1 However, an alternative source of beta-cells has recently been proposed based on neogenesis from a Ngn3-positive population present in regenerating pancreatic ducts.2 The appearance of beta-cells from Ngn3-positive progenitors is reminiscent of normal pancreas development, and Ngn3-expressing cells isolated from regenerating pancreas can generate the full repertoire of endocrine phenotypes. The isolation and characterisation of the equivalent human progenitors may represent a significant step forward in the hunt for a cure for diabetes.


Assuntos
Células Secretoras de Insulina/fisiologia , Pâncreas/citologia , Regeneração , Células-Tronco , Animais , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Linhagem da Célula , Humanos , Células Secretoras de Insulina/citologia , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Pâncreas/crescimento & desenvolvimento , Pâncreas/fisiologia , Células-Tronco/citologia , Células-Tronco/fisiologia
4.
Nucleic Acids Res ; 30(1): 137-41, 2002 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-11752275

RESUMO

The Proteome Division of Incyte Genomics has released new volumes to the BioKnowledge Library to add human, mouse and rat protein information to its rich collection of model organism Proteome Databases. The Human Proteome Survey Database (HumanPSD) compiles the fundamental properties of more than 25 000 characterized mammalian proteins. HumanPSD includes clear, concise and current protein descriptions (Title Lines), the protein sequence, calculated physical properties, precomputed BLAST alignments, controlled-vocabulary protein properties and Gene Ontology terms, and a list of published references. Each report also contains expression data, Pfam domain information and an associated Mouse Mutant Phenotype section describing behavioral, physiological and cellular phenotypes for over 1500 mouse mutant phenotypes. GPCR-PD contains more than 3200 Protein Reports from the three mammalian species for G protein-coupled receptors, their protein ligands, associated G-proteins and their downstream signaling proteins. In addition to the features described above, each GPCR-PD Protein Report displays annotations of experimental findings from over 10 000 publications. These databases provide important new volumes of Proteome's BioKnowledge Library (http://www.incyte.com), integrating protein information from model organisms with the human proteome.


Assuntos
Bases de Dados de Proteínas , Proteínas Heterotriméricas de Ligação ao GTP/metabolismo , Proteoma/genética , Receptores de Superfície Celular/genética , Sequência de Aminoácidos , Animais , Humanos , Armazenamento e Recuperação da Informação , Internet , Ligantes , Camundongos , Mutação , Fenótipo , Estrutura Terciária de Proteína , Proteoma/química , Proteoma/fisiologia , Ratos , Receptores de Superfície Celular/química , Receptores de Superfície Celular/fisiologia , Alinhamento de Sequência , Transdução de Sinais , Vocabulário Controlado
5.
Cell Rep ; 14(12): 2819-32, 2016 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-26997270

RESUMO

Thymic epithelial cells (TECs) are critically required for T cell development, but the cellular mechanisms that maintain adult TECs are poorly understood. Here, we show that a previously unidentified subpopulation, EpCam(+)UEA1(-)Ly-51(+)PLET1(+)MHC class II(hi), which comprises <0.5% of adult TECs, contains bipotent TEC progenitors that can efficiently generate both cortical (c) TECs and medullary (m) TECs. No other adult TEC population tested in this study contains this activity. We demonstrate persistence of PLET1(+)Ly-51(+) TEC-derived cells for 9 months in vivo, suggesting the presence of thymic epithelial stem cells. Additionally, we identify cTEC-restricted short-term progenitor activity but fail to detect high efficiency mTEC-restricted progenitors in the adult thymus. Our data provide a phenotypically defined adult thymic epithelial progenitor/stem cell that is able to generate both cTECs and mTECs, opening avenues for improving thymus function in patients.


Assuntos
Células-Tronco/metabolismo , Timo/citologia , Animais , Feminino , Citometria de Fluxo , Humanos , Imuno-Histoquímica , Imunofenotipagem , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos CBA , Fenótipo , Proteínas da Gravidez/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Células-Tronco/citologia , Transcriptoma
6.
PLoS One ; 11(3): e0151666, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26983083

RESUMO

Thymus function requires extensive cross-talk between developing T-cells and the thymic epithelium, which consists of cortical and medullary TEC. The transcription factor FOXN1 is the master regulator of TEC differentiation and function, and declining Foxn1 expression with age results in stereotypical thymic involution. Understanding of the dynamics of Foxn1 expression is, however, limited by a lack of single cell resolution data. We have generated a novel reporter of Foxn1 expression, Foxn1G, to monitor changes in Foxn1 expression during embryogenesis and involution. Our data reveal that early differentiation and maturation of cortical and medullary TEC coincides with precise sub-lineage-specific regulation of Foxn1 expression levels. We further show that initiation of thymic involution is associated with reduced cTEC functionality, and proportional expansion of FOXN1-negative TEC in both cortical and medullary sub-lineages. Cortex-specific down-regulation of Foxn1 between 1 and 3 months of age may therefore be a key driver of the early stages of age-related thymic involution.


Assuntos
Diferenciação Celular/fisiologia , Desenvolvimento Embrionário/fisiologia , Células Epiteliais/metabolismo , Fatores de Transcrição Forkhead/metabolismo , Timo/metabolismo , Envelhecimento/fisiologia , Animais , Linhagem da Célula/fisiologia , Regulação para Baixo , Fatores de Transcrição Forkhead/genética , Camundongos
7.
Regen Med ; 10(3): 317-29, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25933240

RESUMO

The thymus is required for generation of a self-tolerant, self-restricted T-cell repertoire. The capacity to manipulate or replace thymus function therapeutically would be beneficial in a variety of clinical settings, including for improving recovery following bone marrow transplantation, restoring immune system function in the elderly and promoting tolerance to transplanted organs or cells. An attractive strategy would be transplantation of thymus organoids generated from cells produced in vitro, for instance from pluripotent stem cells. Here, we review recent progress toward this goal, focusing on advances in directing differentiation of pluripotent stem cells to thymic epithelial cells, a key cell type of the thymic stroma, and related direct reprogramming strategies.


Assuntos
Reprogramação Celular/imunologia , Tolerância Imunológica , Organoides , Células-Tronco Pluripotentes , Nicho de Células-Tronco/imunologia , Timo , Animais , Humanos , Organoides/citologia , Organoides/imunologia , Organoides/transplante , Células-Tronco Pluripotentes/citologia , Células-Tronco Pluripotentes/imunologia , Timo/citologia , Timo/imunologia , Timo/transplante
8.
Nat Cell Biol ; 16(9): 902-8, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25150981

RESUMO

A central goal of regenerative medicine is to generate transplantable organs from cells derived or expanded in vitro. Although numerous studies have demonstrated the production of defined cell types in vitro, the creation of a fully intact organ has not been reported. The transcription factor forkhead box N1 (FOXN1) is critically required for development of thymic epithelial cells (TECs), a key cell type of the thymic stroma. Here, we show that enforced Foxn1 expression is sufficient to reprogramme fibroblasts into functional TECs, an unrelated cell type across a germ-layer boundary. These FOXN1-induced TECs (iTECs) supported efficient development of both CD4(+) and CD8(+) T cells in vitro. On transplantation, iTECs established a complete, fully organized and functional thymus, that contained all of the TEC subtypes required to support T-cell differentiation and populated the recipient immune system with T cells. iTECs thus demonstrate that cellular reprogramming approaches can be used to generate an entire organ, and open the possibility of widespread use of thymus transplantation to boost immune function in patients.


Assuntos
Fibroblastos/fisiologia , Fatores de Transcrição Forkhead/biossíntese , Timo/citologia , Animais , Diferenciação Celular , Células Cultivadas , Células Epiteliais/fisiologia , Células Epiteliais/transplante , Feminino , Fatores de Transcrição Forkhead/genética , Expressão Gênica , Masculino , Camundongos , Camundongos da Linhagem 129 , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Medicina Regenerativa , Linfócitos T/fisiologia
9.
Cell Reprogram ; 16(5): 314-23, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25153359

RESUMO

Primary hepatocytes rapidly dedifferentiate when cultured in vitro. We have studied the mechanism of hepatocyte dedifferentiation by using two culture media: one that maintains hepatocytes in a differentiated state and another that allows dedifferentiation. We show that dedifferentiation involves partial transformation of hepatocytes into cells that resemble biliary epithelial cells. Lineage labeling and time-lapse filming confirm that the dedifferentiated cells are derived from hepatocytes and not from contaminating ductal or fibroblastic cells in the original culture. Furthermore, we establish that the conversion of hepatocytes to biliary-like cells is regulated by mutual antagonism of CCAAT/enhancer binding protein alpha (C/EBPα) and SOX9, which have opposing effects on the expression of hepatocyte and ductal genes. Thus, hepatocyte dedifferentiation induces the biliary gene expression program by alleviating C/EBPα-mediated repression of Sox9. We propose that reciprocal antagonism of C/EBPα and SOX9 also operates in the formation of hepatocytes and biliary ducts from hepatoblasts during normal embryonic development. These data demonstrate that reprogramming of differentiated cells can be used to model the acquisition and maintenance of cell fate in vivo.


Assuntos
Proteína alfa Estimuladora de Ligação a CCAAT/genética , Transdiferenciação Celular , Hepatócitos/citologia , Fatores de Transcrição SOX9/genética , Animais , Linhagem da Célula , Células Cultivadas , Meios de Cultura , Hepatócitos/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Ratos , Reação em Cadeia da Polimerase Via Transcriptase Reversa
10.
Methods Mol Biol ; 636: 285-92, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-20336529

RESUMO

Transdifferentiation is defined as the conversion of one cell type to another. One well-documented example of transdifferentiation is the conversion of pancreatic cells to hepatocytes. Here we describe a robust in vitro model to study pancreas to liver transdifferentiation. It is based on the addition of the synthetic glucocorticoid dexamethasone to the rat pancreatic exocrine cell line AR42J. Following glucocorticoid treatment, cells resembling hepatocytes are induced. Transdifferentiated hepatocytes express many of the properties of bona fide hepatocytes, e.g. production of albumin and ability to respond to xenobiotics. These hepatocytes can be used for studying liver function in vitro as well as studying the molecular basis of transdifferentiation.


Assuntos
Diferenciação Celular , Linhagem Celular/efeitos dos fármacos , Reprogramação Celular , Dexametasona/farmacologia , Hepatócitos , Pâncreas/citologia , Animais , Diferenciação Celular/efeitos dos fármacos , Diferenciação Celular/fisiologia , Hepatócitos/citologia , Hepatócitos/fisiologia , Humanos , Pâncreas/efeitos dos fármacos , Ratos
12.
Dev Dyn ; 238(6): 1412-21, 2009 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-19334276

RESUMO

We show that replication defective adenovirus can be used for localized overexpression of a chosen gene in Xenopus tadpoles. Xenopus contains two homologs of the Coxsackie and Adenovirus Receptor (xCAR1 and 2), both of which can confer sensitivity for adenovirus infection. xCAR1 mRNA is present from the late gastrula stage and xCAR2 throughout development, both being widely expressed in the embryo and tadpole. Consistent with the expression of the receptors, adenovirus will infect a wide range of Xenopus tissues cultured in vitro. It will also infect early embryos when injected into the blastocoel or archenteron cavities. Furthermore, adenovirus can be delivered by localized injection to tadpoles and will infect a patch of cells around the injection site. The expression of green fluorescent protein in infected cells persists for several weeks. This new gene delivery method complements the others that are already available. Developmental Dynamics 238:1412-1421, 2009. (c) 2009 Wiley-Liss, Inc.


Assuntos
Adenoviridae , Regulação da Expressão Gênica no Desenvolvimento , Técnicas de Transferência de Genes , Proteínas de Xenopus/metabolismo , Xenopus laevis/genética , Adenoviridae/genética , Adenoviridae/metabolismo , Sequência de Aminoácidos , Animais , Células CHO , Cricetinae , Cricetulus , Humanos , Dados de Sequência Molecular , Receptores Virais/genética , Receptores Virais/metabolismo , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Alinhamento de Sequência , Proteínas de Xenopus/genética , Xenopus laevis/metabolismo
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