RESUMEN
T cell homeostasis is essential for the functioning of the vertebrate immune system, but the intracellular signals required for T cell homeostasis are largely unknown. We here report that the WD-repeat protein family member coronin-1, encoded by the gene Coro1a, is essential in the mouse for T cell survival through its promotion of Ca2+ mobilization from intracellular stores. Upon T cell receptor triggering, coronin-1 was essential for the generation of inositol-1,4,5-trisphosphate from phosphatidylinositol-4,5-bisphosphate. The absence of coronin-1, although it did not affect T cell development, resulted in a profound defect in Ca2+ mobilization, interleukin-2 production, T cell proliferation and T cell survival. We conclude that coronin-1, through activation of Ca2+ release from intracellular stores, is an essential regulator of peripheral lymphocyte survival.
Asunto(s)
Calcio/metabolismo , Inositol 1,4,5-Trifosfato/biosíntesis , Proteínas de Microfilamentos/fisiología , Receptores de Antígenos de Linfocitos T/metabolismo , Linfocitos T/inmunología , Actinas/metabolismo , Animales , Señalización del Calcio/genética , Señalización del Calcio/fisiología , Supervivencia Celular/genética , Supervivencia Celular/inmunología , Líquido Intracelular/inmunología , Líquido Intracelular/metabolismo , Activación de Linfocitos/genética , Activación de Linfocitos/inmunología , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Noqueados , Proteínas de Microfilamentos/deficiencia , Proteínas de Microfilamentos/genética , Receptores de Antígenos de Linfocitos T/fisiología , Linfocitos T/metabolismo , Fosfolipasas de Tipo C/metabolismoRESUMEN
Cell competition is an emerging principle underlying selection for cellular fitness during development and disease. Competition may be relevant for cancer, but an experimental link between defects in competition and tumorigenesis is elusive. In the thymus, T lymphocytes develop from precursors that are constantly replaced by bone-marrow-derived progenitors. Here we show that in mice this turnover is regulated by natural cell competition between 'young' bone-marrow-derived and 'old' thymus-resident progenitors that, although genetically identical, execute differential gene expression programs. Disruption of cell competition leads to progenitor self-renewal, upregulation of Hmga1, transformation, and T-cell acute lymphoblastic leukaemia (T-ALL) resembling the human disease in pathology, genomic lesions, leukaemia-associated transcripts, and activating mutations in Notch1. Hence, cell competition is a tumour suppressor mechanism in the thymus. Failure to select fit progenitors through cell competition may explain leukaemia in X-linked severe combined immune deficiency patients who showed thymus-autonomous T-cell development after therapy with gene-corrected autologous progenitors.
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Transformación Celular Neoplásica , Células Madre Hematopoyéticas/citología , Leucemia-Linfoma Linfoblástico de Células T Precursoras/patología , Timo/citología , Animales , División Celular , Movimiento Celular , Transformación Celular Neoplásica/genética , Progresión de la Enfermedad , Femenino , Regulación Neoplásica de la Expresión Génica , Proteínas HMGA/genética , Células Madre Hematopoyéticas/metabolismo , Humanos , Masculino , Ratones , Ratones Endogámicos C57BL , Leucemia-Linfoma Linfoblástico de Células T Precursoras/genética , Receptor Notch1/genética , Linfocitos T/citología , Linfocitos T/metabolismo , Linfocitos T/patología , Timo/patología , Transcriptoma/genéticaRESUMEN
The cellular differentiation pathway originating from the bone marrow leading to early T lymphocytes remains poorly understood. The view that T cells branch off from a lymphoid-restricted pathway has recently been challenged by a model proposing a common progenitor for T cell and myeloid lineages. We generated interleukin-7 receptor alpha (Il7r) Cre recombinase knockin mice and traced lymphocyte development by visualizing the history of Il7r expression. Il7r fate mapping labeled all T cells but few myeloid cells. More than 85% of T cell progenitors were Il7r reporter(+) and, hence, had arisen from an Il7r-expressing pathway. In contrast, the overwhelming majority of myeloid cells in the thymus were derived from Il7r reporter(-) cells. Thus, lymphoid-restricted progenitors are the major route to T cells, and distinct origins of lymphoid and myeloid lineages represent a fundamental hallmark of hematopoiesis.
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Linaje de la Célula , Células Mieloides/citología , Células Mieloides/inmunología , Linfocitos T/citología , Linfocitos T/inmunología , Timo/citología , Timo/inmunología , Alelos , Animales , Diferenciación Celular , Ratones , Receptores de Interleucina-7/genética , Receptores de Interleucina-7/inmunologíaRESUMEN
Notch1 signaling is required for T cell development and has been implicated in fate decisions in the thymus. We showed that Notch1 deletion in progenitor T cells (pro-T cells) revealed their latent developmental potential toward becoming conventional and plasmacytoid dendritic cells. In addition, Notch1 deletion in pro-T cells resulted in large numbers of thymic B cells, previously explained by T-to-B cell fate conversion. Single-cell genotyping showed, however, that the majority of these thymic B cells arose from Notch1-sufficient cells by a cell-extrinsic pathway. Fate switching nevertheless exists for a subset of thymic B cells originating from Notch1-deleted pro-T cells. Chimeric mice lacking the Notch ligand delta-like 4 (Dll4) in thymus epithelium revealed an essential role for Dll4 in T cell development. Thus, Notch1-Dll4 signaling fortifies T cell commitment by suppressing non-T cell lineage potential in pro-T cells, and normal Notch1-driven T cell development repels excessive B cells in the thymus.
Asunto(s)
Linfocitos B/inmunología , Células Dendríticas/inmunología , Eliminación de Gen , Receptor Notch1/genética , Linfocitos T/inmunología , Timo/citología , Animales , Linaje de la Célula , Citometría de Flujo , Ratones , Ratones Endogámicos C57BL , Receptor Notch1/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
Introduction: Durability of immune protection against reinfection with SARS-CoV-2 remains enigmatic, especially in the pediatric population and in the context of immune-evading variants of concern. Obviously, this knowledge is required for measures to contain the spread of infection and in selecting rational preventive measures. Methods: Here, we investigated the serum neutralization capacity of 36 seropositive adults and 34 children approximately one year after infection with the ancestral Wuhan strain of SARS-CoV-2 by using a pseudovirus neutralization assay. Results: We found that 88.9% of seropositive adult (32/36) and 94.1% of seropositive children (32/34) convalescents retained the neutralizing activity against the SARS-CoV-2 Wuhan strain (WT). Although, the neutralization effect against Omicron BA.1 (B.1.1.529.1) was significantly lower, 70.6% (24/34) of children and 41.7% (15/36) of adults possessed BA.1 cross-neutralizing antibodies. The spike 1 (S1)-specific T cell recall capacity using an activation-induced marker assay was analyzed in 18 adults and 16 children. All participants had detectable S1-specific CD4 T cells against WT, and 72.2% (13/18) adults and 81,3% (13/16) children had detectable S1 WT-specific CD8 T cells. CD4 cross-reactivity against BA.1 was demonstrated in all investigated adults (18/18), and 66.7% (12/18) adult participants had also detectable specific CD8 BA.1 T cells while we detected BA.1 S1 reactive CD4 and CD8 T cells in 81.3% (13/16) children. Discussion: Together, our findings demonstrate that infection with the ancestral strain of SARS-CoV-2 in children as well as in adults induces robust serological as well as T cell memory responses that persist over at least 12 months. This suggests persistent immunological memory and partial cross-reactivity against Omicron BA.1.
RESUMEN
The COVID-19 course and immunity differ in children and adults. We analyzed immune response dynamics in 28 families up to 12 months after mild or asymptomatic infection. Unlike adults, the initial response is plasmablast-driven in children. Four months after infection, children show an enhanced specific antibody response and lower but detectable spike 1 protein (S1)-specific B and T cell responses than their parents. While specific antibodies decline, neutralizing antibody activity and breadth increase in both groups. The frequencies of S1-specific B and T cell responses remain stable. However, in children, one year after infection, an increase in the S1-specific IgA class switch and the expression of CD27 on S1-specific B cells and T cell maturation are observed. These results, together with the enhanced neutralizing potential and breadth of the specific antibodies, suggest a progressive maturation of the S1-specific immune response. Hence, the immune response in children persists over 12 months but dynamically changes in quality, with progressive neutralizing, breadth, and memory maturation. This implies a benefit for booster vaccination in children to consolidate memory formation.
Asunto(s)
COVID-19 , Adulto , Niño , Humanos , SARS-CoV-2 , Formación de Anticuerpos , Anticuerpos Neutralizantes , Inmunización SecundariaRESUMEN
The human Mixed-Lineage-Leukemia-5 (MLL5) gene is located in a genomic region frequently deleted in patients with myeloid malignancies and encodes a widely expressed nuclear protein most closely related to MLL1, a Trithorax transcriptional regulator with established involvement in leukemogenesis. Although the physiologic function of MLL5 is completely unknown, domain structure and homology to transcriptional regulators with histone methyltransferase activity suggest a role in epigenetic gene regulation. To investigate physiologic functions of Mll5, we have generated a knockout mouse mutant using Cre/loxP technology. Adult homozygous Mll5-deficient mice are obtained at reduced frequency because of postnatal lethality. Surviving animals display a variety of abnormalities, including male infertility, retarded growth, and defects in multiple hematopoietic lineages. Interestingly, Mll5(-/-) mice die of sublethal whole-body irradiation but can be rescued with wild-type bone marrow grafts. Flow cytometric ana-lysis, bone marrow reconstitution, and in vivo BrdU-labeling experiments reveal numerical, functional, and cell-cycle defects in the lineage-negative Sca-1(+), Kit(+) (LSK) population, which contains short- and long-term hematopoietic stem cells. Together, these in vivo findings establish several nonredundant functions for Mll5, including an essential role in regulating proliferation and functional integrity of hematopoietic stem/progenitor cells.
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Trastornos del Crecimiento/genética , Hematopoyesis/inmunología , Células Madre Hematopoyéticas/citología , N-Metiltransferasa de Histona-Lisina/genética , N-Metiltransferasa de Histona-Lisina/metabolismo , Proteína de la Leucemia Mieloide-Linfoide/genética , Proteína de la Leucemia Mieloide-Linfoide/metabolismo , Animales , Diferenciación Celular/inmunología , Femenino , Genes Letales , Trastornos del Crecimiento/inmunología , Heterocigoto , Infertilidad Masculina/genética , Infertilidad Masculina/inmunología , Linfocitos/citología , Masculino , Ratones , Ratones Noqueados , Fenotipo , Embarazo , Tolerancia a Radiación/genéticaRESUMEN
Benzodifuran-functionalised pyrene and anthracene fluorophores 1 and 2 were obtained in reasonable yields. Their single crystal structures, electrochemical, optical absorption, and fluorescence characteristics have been described. They show strong luminescence with high quantum yields of 0.53 for 1 and 0.48 for 2.
RESUMEN
An efficient synthetic approach to construct a fully substituted benzo[1,2-b:4,5-b']difuran (BDF) 2a via base-catalyzed double annulations is presented. Compound 2a can readily undergo Suzuki, Heck, and Sonogashira coupling reactions to afford in good yields a manifold of extended pi-conjugated BDF derivatives, e.g., with pyridine termini (4-6) and with different spacers. These are highly luminescent materials that undergo two reversible one-electron oxidations. Remarkably, their photophysical and electrochemical properties can be largely tuned by methylation or protonation. Consequently, they can function as pH-dependent fluorescence switches. Finally, the observed electronic properties are explained on the basis of density functional theory.
Asunto(s)
Benzofuranos/síntesis química , Piridinas/química , Benzofuranos/química , Simulación por Computador , Concentración de Iones de Hidrógeno , Luminiscencia , Mediciones Luminiscentes , Estructura Molecular , Oxidación-ReducciónRESUMEN
Mast cell carboxypeptidase A (Mc-cpa) is a highly conserved secretory granule protease. The onset of expression in mast cell progenitors and lineage specificity suggest an important role for Mc-cpa in mast cells. To address the function of Mc-cpa, we generated Mc-cpa-null mice. Mc-cpa-/- mast cells lacked carboxypeptidase activity, revealing that Mc-cpa is a nonredundant enzyme. While Mc-cpa-/- peritoneal mast cells were ultrastructurally normal and synthesized normal amounts of heparin, they displayed striking histochemical and biochemical hallmarks of immature mast cells. Wild-type peritoneal mast cells had a mature phenotype characterized by differential histochemical staining with proteoglycan-reactive dyes (cells do not stain with alcian blue but stain with safranin and with berberine) and a high side scatter to forward scatter ratio by flow cytometry and were detergent resistant. In contrast, Mc-cpa-/- peritoneal mast cells, like immature bone marrow-derived cultured mast cells, stained with alcian blue normally or weakly and either did not stain with safranin and berberine or stained weakly, had a low side scatter to forward scatter ratio, and were detergent sensitive. This phenotype was partially ameliorated with age. Thus, histochemistry and flow cytometry, commonly used to measure mast cell maturation, deviated from morphology in Mc-cpa-/- mice. The Mc-cpa-/- mast cell phenotype was not associated with defects in degranulation in vitro or passive cutaneous anaphylaxis in vivo. Collectively, Mc-cpa plays a crucial role for the generation of phenotypically mature mast cells.
Asunto(s)
Carboxipeptidasas A/fisiología , Mastocitos/enzimología , Mastocitos/ultraestructura , Animales , Anticuerpos/inmunología , Berberina/farmacología , Carboxipeptidasas A/análisis , Carboxipeptidasas A/genética , Heparina/inmunología , Heparina/metabolismo , Histocitoquímica , Mastocitos/efectos de los fármacos , Ratones , Ratones Mutantes , Proteínas Quimioatrayentes de Monocitos/metabolismo , Fenotipo , Proteoglicanos/metabolismo , Serina Endopeptidasas/metabolismo , TriptasasRESUMEN
beta-Catenin, a protein that functions in cadherin-mediated cell-cell adhesion as well as in signal transduction, has received increasing attention in recent years due to its role as an oncogene in various human cancers. The primary sequence of the human beta-catenin gene (CTNNB1) has been known for some time, but that of the rat beta-catenin gene (Ctnnb1) has not heretofore been studied in detail. We report here the primary structure of Ctnnb1 using PCR-based methods and direct sequencing. The size of the complete Ctnnb1 gene was determined to be 9082 bp. We found the rat Ctnnb1 gene to contain 14 exons, ranging in size from 61 to 356 bp, and 13 introns ranging in size from 76 to 2524 bp. The transcription start site appears to be 157 bp upstream of the ATG codon located in exon 1. The resulting transcript is 2650 nucleotides long (encoding a protein of 781 amino acids). We found the 5' UTR to consist of 157 nucleotides and the 3' UTR to be 147 nucleotides long. The region coding for the glycogen synthase kinase-3beta domain of beta-catenin is located in exon 2 of rat Ctnnb1, in contrast to human CTNNB1 in which it is found in exon 3. Based on the newly acquired knowledge of the primary sequence, more than a dozen 2-amino-3-methylimidazo[4,5-f]quinoline (IQ)-induced rat liver tumors were screened for the presence or absence of mutations in all 14 exons of rat Ctnnb1. Surprisingly, no mutations were found. The results are discussed in the context of the organ-specificity of IQ-induced mutations in beta-catenin, being highly prevalent in colon tumors, but much less common in liver tumors.
Asunto(s)
Proteínas del Citoesqueleto/genética , Neoplasias Hepáticas Experimentales/genética , Transactivadores , Secuencia de Aminoácidos , Animales , Secuencia de Bases , ADN/química , ADN/genética , ADN Complementario/química , ADN Complementario/genética , Exones , Genes/genética , Intrones , Neoplasias Hepáticas Experimentales/inducido químicamente , Masculino , Datos de Secuencia Molecular , Mutación , Polimorfismo Conformacional Retorcido-Simple , Quinolinas , ARN Mensajero/genética , ARN Mensajero/metabolismo , Ratas , Ratas Endogámicas F344 , Análisis de Secuencia de ADN , beta CateninaRESUMEN
Effects of metallothionein (MT) on cadmium absorption and transfer pathways during gestation and lactation in mice were investigated. Female 129/SvJ metallothionein-knockout (MT1,2KO) and metallothionein-normal (MTN) mice received drinking water containing trace amounts of (109)CdCl(2) (0.15 ng Cd/ml; 0.074 micro Ci (109)Cd/ml). (109)Cd and MT in maternal, fetal, and pup tissues were measured on gestation days 7, 14, and 17 and lactation day 11. In dams, MT influenced both the amount of (109)Cd transferred from intestine into body (two- to three-fold higher in MT1,2KO than MTN dams) and tissue-specific (109)Cd distribution (higher liver/kidney ratio in MT1,2KO dams). Placental (109)Cd concentrations in MT1,2KO dams were three- and seven-fold higher on gestation days 14 and 17, respectively, than in MTN dams. Fetal (109)Cd levels were low in both mouse types, but at least 10-fold lower in MTN fetuses. MT had no effect on the amount of (109)Cd transferred to pups via milk; furthermore, 85-90% of total pup (109)Cd was recovered in gastrointestinal tracts of both types, despite high duodenal MT only in MTN pups. A relatively large percentage of milk-derived intestinal (109)Cd was transferred to other pup tissues in both MT1,2KO and MTN pups (14 and 10%, respectively). These results demonstrate that specific sequestration of cadmium by both maternal and neonatal intestinal tract does not require MT. Although MT decreased oral cadmium transfer from intestine to body tissues at low cadmium exposure levels, MT did not play a major role in restricting transfer of cadmium from dam to fetus via placenta and to neonate via milk.
Asunto(s)
Animales Recién Nacidos/metabolismo , Cadmio/farmacocinética , Lactancia/metabolismo , Metalotioneína/metabolismo , Preñez/metabolismo , Administración Oral , Animales , Cadmio/administración & dosificación , Radioisótopos de Cadmio , Ingestión de Líquidos , Femenino , Intestino Delgado/efectos de los fármacos , Intestino Delgado/metabolismo , Lactancia/efectos de los fármacos , Masculino , Intercambio Materno-Fetal , Metalotioneína/genética , Ratones , Ratones Endogámicos , Ratones Noqueados , Placenta/metabolismo , Embarazo , Abastecimiento de AguaRESUMEN
The carcinogens 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) and 1,2-dimethylhydrazine (DMH) induce colon tumors in the rat that contain mutations in beta-catenin, but the mutation pattern can be influenced by exposure to dietary phytochemicals, such as the water-soluble derivative of chlorophyll called chlorophyllin. Whereas chlorophyllin is an effective blocking agent during the initiation phase, post-initiation responses depend upon the exposure protocol, and can be influenced by the initiating agent and the concentration of chlorophyllin. Post-initiation treatment with 0.001% chlorophyllin (w/v) in the drinking water promoted colon carcinogenesis in the rat, but much higher concentrations (1.0% chlorophyllin) led to suppression. Bromodeoxyuridine and terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) indices revealed that the promotional concentration of 0.001% chlorophyllin increased the ratio of cell proliferation to apoptosis in the colonic crypts, whereas concentrations in the range 0.0l-1.0% chlorophyllin modestly reduced this ratio. Molecular studies showed that the spectrum of beta-catenin mutations was markedly different in chlorophyllin-promoted colon tumors--many of the mutations led to direct substitutions of critical Ser/Thr residues within the glycogen synthase kinase-3beta (GSK-3beta) region, whereas in all other groups, including DMH and IQ controls, the mutations typically affected amino acids adjacent to Ser(33). Substitution of critical Ser/Thr residues caused beta-catenin and c-Jun proteins to be markedly over-expressed compared with tumors in which the mutations substituted amino acid residues flanking these critical Ser/Thr sites. In a separate study, rats were exposed to IQ or azoxymethane (AOM), a metabolite of DMH, and they were treated post-initiation with chlorophyllin, chlorophyll, copper, or phytol in the diet. Natural chlorophyll (0.08%) suppressed AOM- and IQ-induced aberrant crypt foci (ACF), whereas chlorophyllin had no effect and copper promoted the number of small ACF induced by IQ. The results suggest that further investigation of the dose-response for suppression versus promotion by chlorophyll and chlorophyllin is warranted, including studies of the beta-catenin/Tcf signaling pathway and its influence on cell proliferation and apoptosis in the colonic crypt.
Asunto(s)
1,2-Dimetilhidrazina/toxicidad , Anticarcinógenos/farmacología , Carcinógenos/toxicidad , Clorofila/farmacología , Clorofilidas/farmacología , Neoplasias del Colon/inducido químicamente , Neoplasias del Colon/prevención & control , Proteínas del Citoesqueleto/fisiología , Transactivadores/fisiología , Animales , Apoptosis/efectos de los fármacos , Neoplasias del Colon/patología , Quinolinas/toxicidad , Ratas , beta CateninaRESUMEN
There is growing interest in the potential health benefits of tea, and a recent report described the potent antimutagenic activity of white tea in comparison with green tea against several heterocyclic amines, including 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) [Mutat. Res. 495 (2001) 61]. We compared the inhibitory effects of white and green teas with sulindac, a nonsteroidal anti-inflammatory agent, in two different mouse models of intestinal tumorigenesis. In the Apc(min) mouse, white and green teas given at human-relevant concentrations (1.5% w/v, 2-min brew), and sulindac (80 ppm in the drinking water), each suppressed polyp formation by approximately 50%, and the combination of white tea plus sulindac was more effective than either treatment alone (P=0.05). Mice expressing an N-terminally truncated, oncogenic version of beta-catenin (A 33(delta N beta-cat) mutant mice) developed colonic aberrant crypt foci (ACF) spontaneously, but PhIP treatment increased the incidence and number of ACF per colon. In the normal-looking intestinal mucosa of Apc(min) and A 33(delta N beta-cat) mice, white tea plus sulindac treatment markedly attenuated the expression of beta-catenin protein, and this was recapitulated in vitro in cells transiently transfected with beta-catenin plus Tcf-4 and treated with tea or the major tea polyphenol epigallocatechin-3-gallate (EGCG). Expression of a beta-catenin/Tcf reporter was inhibited by EGCG in the transfected cells, and the beta-catenin/Tcf target genes cyclin D1 and c-jun were downregulated in vivo by tea plus sulindac treatment. Collectively, the data support a chemopreventive role for tea and sulindac against intermediate and late stages of colon cancer, via effects on the beta-catenin/Tcf signaling pathway.
Asunto(s)
Proteína de la Poliposis Adenomatosa del Colon/metabolismo , Antiinflamatorios no Esteroideos/farmacología , Catequina/análogos & derivados , Neoplasias Intestinales/prevención & control , Extractos Vegetales/farmacología , Pólipos/prevención & control , Sulindac/farmacología , Té , Proteína de la Poliposis Adenomatosa del Colon/deficiencia , Proteína de la Poliposis Adenomatosa del Colon/genética , Animales , Catequina/farmacología , Línea Celular , Proteínas del Citoesqueleto/deficiencia , Proteínas del Citoesqueleto/genética , Proteínas del Citoesqueleto/metabolismo , Combinación de Medicamentos , Imidazoles/toxicidad , Mucosa Intestinal/efectos de los fármacos , Mucosa Intestinal/metabolismo , Neoplasias Intestinales/inducido químicamente , Neoplasias Intestinales/metabolismo , Luciferasas/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Mutantes , Pólipos/inducido químicamente , Pólipos/metabolismo , Transactivadores/deficiencia , Transactivadores/genética , Transactivadores/metabolismo , beta CateninaRESUMEN
Standard metabolism cages are inadequate for collecting excreta from dams during parturition because newborn pups can fall through the grating into the excreta collection area and out of reach of the dam. A nest box was designed that facilitates excreta collection from mouse dams continuously housed in metabolism cages from conception, through parturition, and into lactation and provides a safe, warm environment for pups during their first week of life. The nest box was tested by using pregnant and lactating mice of two varieties of strain 129/SvJ, metallothionein-normal and metallothionein-knockout; non-pregnant mice were used as controls. Pregnant mice (with nest box) and non-pregnant mice (without nest box) each twice received a solution of 109CdCl2 by gavage. Dams with nest boxes fastidiously urinated and defecated outside the nest box. The percentage of gavage 109Cd dose recovered in dam feces was the same after the first gavage (mean6SE, with nest box through parturition, 95%66%; n=5) as after the second gavage (mean6SE, without nest box, 95%66%; n=5). Weights and percentage weight gain of mouse dams were independent of housing conditions (metabolic cage with next box vs. conventional polycarbonate caging). Furthermore, pup growth and survival were unaffected by the inclusion of the nest box or by its removal at 1 week after birth. Therefore, the described nest box provides for the first time a way to quantitatively collect excreta from mouse dams through pregnancy, parturition, and the early postnatal period. Additional experiments are needed to test its application to other animal species and strains of mice, including those with poor mothering behavior.
RESUMEN
Expression of the pre-T cell receptor α (pTα) gene has been exploited in previous studies as a molecular marker to identify tiny cell populations in bone marrow (BM) and blood that were suggested to contain physiologically relevant thymus settling progenitors (TSPs). But to what extent these cells genuinely contribute to thymopoiesis has remained obscure. We have generated a novel pTα(iCre) knockin mouse line and performed lineage-tracing experiments to precisely quantitate the contribution of pTα-expressing progenitors to distinct differentiation pathways and to the genealogy of mature hematopoietic cells under physiological in vivo conditions. Using these mice in combination with fluorescent reporter strains, we observe highly consistent labeling patterns that identify pTα expression as a faithful molecular marker of T lineage commitment. Specifically, the fate of pTα-expressing progenitors was found to include all αß and most γδ T cells but, in contrast to previous assumptions, to exclude B, NK, and thymic dendritic cells. Although we could detect small numbers of T cell progenitors with a history of pTα expression in BM and blood, our data clearly exclude these populations as physiologically important precursors of thymopoiesis and indicate that they instead belong to a pathway of T cell maturation previously defined as extrathymic.
Asunto(s)
Diferenciación Celular/inmunología , Regulación de la Expresión Génica/inmunología , Linfopoyesis/fisiología , Glicoproteínas de Membrana/inmunología , Receptores de Antígenos de Linfocitos T alfa-beta/inmunología , Timocitos/inmunología , Timo/inmunología , Animales , Médula Ósea/inmunología , Diferenciación Celular/genética , Regulación de la Expresión Génica/genética , Glicoproteínas de Membrana/genética , Ratones , Ratones Noqueados , Receptores de Antígenos de Linfocitos T alfa-beta/genética , Receptores de Antígenos de Linfocitos T gamma-delta/genética , Receptores de Antígenos de Linfocitos T gamma-delta/inmunología , Timocitos/citología , Timo/citologíaRESUMEN
An efficient synthetic approach to a symmetrically functionalized tetrathiafulvalene (TTF) derivative with two diamine moieties, 2-[5,6-diamino-4,7-bis(4-pentylphenoxy)-1,3-benzodithiol-2-ylidene]-4,7-bis(4-pentylphenoxy)-1,3-benzodithiole-5,6-diamine (2), is reported. The subsequent Schiff-base reactions of 2 afford large π-conjugated multiple donor-acceptor (D-A) arrays, for example, the triad 2-[4,9-bis(4-pentylphenoxy)-1,3-dithiolo[4,5-g]quinoxalin-2-ylidene]-4,9-bis(4-pentylphenoxy)-1,3-dithiolo[4,5-g]quinoxaline (8) and the corresponding tetrabenz[bc,ef,hi,uv]ovalene-fused pentad 1, in good yields and high purity. The novel redox-active nanographene 1 is so far the largest known TTF-functionalized polycyclic aromatic hydrocarbon (PAH) with a well-resolved (1)H NMR spectrum. The electrochemically highly amphoteric pentad 1 and triad 8 exhibit various electronically excited charge-transfer states in different oxidation states, thus leading to intense optical intramolecular charge-transfer (ICT) absorbances over a wide spectral range. The chemical and electrochemical oxidations of 1 result in an unprecedented TTF(â +) radical cation dimerization, thereby leading to the formation of [1(â +)](2) at room temperature in solution due to the stabilizing effect, which arises from strong π-π interactions. Moreover, ICT fluorescence is observed with large solvent-dependent Stokes shifts and quantum efficiencies of 0.05 for 1 and 0.035 for 8 in dichloromethane.
RESUMEN
A tetrathiafulvalene donor has been annulated to the bay region of perylenediimide affording a new pi-conjugated molecular dyad. Various electronic excited charge-transfer states are generated in different oxidation states, leading to almost full absorption in the visible to near-IR region with a high extinction coefficient.
Asunto(s)
Colorantes Fluorescentes/síntesis química , Compuestos Heterocíclicos/química , Imidas/química , Perileno/análogos & derivados , Simulación por Computador , Colorantes Fluorescentes/química , Modelos Químicos , Estructura Molecular , Oxidación-Reducción , Perileno/químicaRESUMEN
Dppa4 (developmental pluripotency-associated 4) has been identified in several high-profile screens as a gene that is expressed exclusively in pluripotent cells. It encodes a nuclear protein with an SAP-like domain and appears to be associated preferentially with transcriptionally active chromatin. Its exquisite expression pattern and results of RNA interference experiments have led to speculation that Dppa4, as well as its nearby homolog Dppa2, might play essential roles in embryonic stem (ES) cell function and/or germ cell development. To rigorously assess suggested roles, we have generated Dppa4-deficient and Dppa4/Dppa2 doubly deficient ES cells, as well as mice lacking Dppa4. Contrary to predictions, we find that Dppa4 is completely dispensable for ES cell identity and germ cell development. Instead, loss of Dppa4 in mice results in late embryonic/perinatal death and striking skeletal defects with partial penetrance. Thus, surprisingly, Dppa4-deficiency affects tissues that apparently never transcribed the gene, and at least some loss-of-function defects manifest phenotypically at an embryonic stage long after physiologic Dppa4 expression has ceased. Concomitant with targeted gene inactivation, we have introduced into the Dppa4 locus a red fluorescent marker (tandem-dimer red fluorescent protein) that is compatible with green fluorescent proteins and allows noninvasive visualization of pluripotent cells and reprogramming events.