RESUMEN
CD4+ T helper 17 (TH17) cells protect barrier tissues but also trigger autoimmunity. The mechanisms behind these opposing processes remain unclear. Here, we found that the transcription factor EGR2 controlled the transcriptional program of pathogenic TH17 cells in the central nervous system (CNS) but not that of protective TH17 cells at barrier sites. EGR2 was significantly elevated in myelin-reactive CD4+ T cells from patients with multiple sclerosis and mice with autoimmune neuroinflammation. The EGR2 transcriptional program was intricately woven within the TH17 cell transcriptional regulatory network and showed high interconnectivity with core TH17 cell-specific transcription factors. Mechanistically, EGR2 enhanced TH17 cell differentiation and myeloid cell recruitment to the CNS by upregulating pathogenesis-associated genes and myelomonocytic chemokines. T cell-specific deletion of Egr2 attenuated neuroinflammation without compromising the host's ability to control infections. Our study shows that EGR2 regulates tissue-specific and disease-specific functions in pathogenic TH17 cells in the CNS.
Asunto(s)
Encefalomielitis Autoinmune Experimental , Esclerosis Múltiple , Animales , Ratones , Diferenciación Celular , Sistema Nervioso Central , Ratones Endogámicos C57BL , Enfermedades Neuroinflamatorias , Células TH1 , Células Th17 , Factores de Transcripción , Virulencia , HumanosRESUMEN
Mechanistic target of rapamycin complex 1 (mTORC1) controls cell growth and proliferation by sensing fluctuations in environmental cues such as nutrients, growth factors, and energy levels. The Rag GTPases (Rags) serve as a critical module that signals amino acid (AA) availability to modulate mTORC1 localization and activity. Recent studies have demonstrated how AAs regulate mTORC1 activity through Rags. Here, we uncover an unconventional pathway that activates mTORC1 in response to variations in threonine (Thr) levels via mitochondrial threonyl-tRNA synthetase TARS2. TARS2 interacts with inactive Rags, particularly GTP-RagC, leading to increased GTP loading of RagA. mTORC1 activity in cells lacking TARS2 is resistant to Thr repletion, showing that TARS2 is necessary for Thr-dependent mTORC1 activation. The requirement of TARS2, but not cytoplasmic threonyl-tRNA synthetase TARS, for this effect demonstrates an additional layer of complexity in the regulation of mTORC1 activity.
Asunto(s)
Diana Mecanicista del Complejo 1 de la Rapamicina/genética , Mitocondrias/metabolismo , Proteínas de Unión al GTP Monoméricas/genética , Treonina-ARNt Ligasa/genética , Treonina/metabolismo , Regulación de la Expresión Génica , Guanosina Difosfato/metabolismo , Guanosina Trifosfato/metabolismo , Células HEK293 , Humanos , Isoenzimas/antagonistas & inhibidores , Isoenzimas/genética , Isoenzimas/metabolismo , Lisosomas/metabolismo , Diana Mecanicista del Complejo 1 de la Rapamicina/metabolismo , Proteínas de Unión al GTP Monoméricas/metabolismo , Unión Proteica , ARN Interferente Pequeño/genética , ARN Interferente Pequeño/metabolismo , Proteína Reguladora Asociada a mTOR/genética , Proteína Reguladora Asociada a mTOR/metabolismo , Transducción de Señal , Treonina-ARNt Ligasa/antagonistas & inhibidores , Treonina-ARNt Ligasa/metabolismoRESUMEN
Type I interferons (IFNs) are critical cytokines in the host defense against invading pathogens. Sustained production of IFNs, however, is detrimental to the host, as it provokes autoimmune diseases. Thus, the expression of IFNs is tightly controlled. We report that the mRNA 5' cap-binding protein 4EHP plays a key role in regulating type I IFN concomitant with controlling virus replication, both in vitro and in vivo. Mechanistically, 4EHP suppresses IFN-ß production by effecting the miR-34a-induced translational silencing of Ifnb1 mRNA. miR-34a is upregulated by both RNA virus infection and IFN-ß induction, prompting a negative feedback regulatory mechanism that represses IFN-ß expression via 4EHP. These findings demonstrate the direct involvement of 4EHP in virus-induced host response, underscoring a critical translational silencing mechanism mediated by 4EHP and miR-34a to impede sustained IFN production. This study highlights an intrinsic regulatory function for miRNA and the translation machinery in maintaining host homeostasis.
Asunto(s)
Factor 4E Eucariótico de Iniciación/inmunología , Inmunidad Innata , MicroARNs/inmunología , Biosíntesis de Proteínas/inmunología , Infecciones por Virus ARN/inmunología , Virus ARN/inmunología , Animales , Factor 4E Eucariótico de Iniciación/genética , Células HEK293 , Humanos , Interferón beta/genética , Interferón beta/inmunología , Ratones , Ratones Transgénicos , MicroARNs/genética , Infecciones por Virus ARN/genética , Virus ARN/genéticaAsunto(s)
Investigación Biomédica , COVID-19/inmunología , Síndrome de Liberación de Citoquinas/inmunología , Citocinas/inmunología , Sistema Inmunológico/inmunología , SARS-CoV-2/inmunología , Síndrome de Respuesta Inflamatoria Sistémica/inmunología , Factores de Edad , Animales , Autoinmunidad , COVID-19/metabolismo , COVID-19/terapia , COVID-19/virología , Síndrome de Liberación de Citoquinas/metabolismo , Síndrome de Liberación de Citoquinas/virología , Citocinas/metabolismo , Interacciones Huésped-Patógeno , Humanos , Sistema Inmunológico/metabolismo , Sistema Inmunológico/virología , Pronóstico , Factores de Riesgo , SARS-CoV-2/patogenicidad , Síndrome de Respuesta Inflamatoria Sistémica/metabolismo , Síndrome de Respuesta Inflamatoria Sistémica/terapia , Síndrome de Respuesta Inflamatoria Sistémica/virologíaAsunto(s)
Angioedema/inmunología , Betacoronavirus/inmunología , Infecciones por Coronavirus/inmunología , Síndrome de Liberación de Citoquinas/inmunología , Citocinas/metabolismo , Neumonía Viral/inmunología , Angioedema/sangre , Angioedema/patología , Angioedema/virología , Enzima Convertidora de Angiotensina 2 , Antiinflamatorios/farmacología , Antiinflamatorios/uso terapéutico , Antivirales/uso terapéutico , Biomarcadores/sangre , COVID-19 , Prueba de COVID-19 , Técnicas de Laboratorio Clínico/métodos , Congresos como Asunto , Infecciones por Coronavirus/sangre , Infecciones por Coronavirus/diagnóstico , Infecciones por Coronavirus/tratamiento farmacológico , Infecciones por Coronavirus/epidemiología , Síndrome de Liberación de Citoquinas/sangre , Síndrome de Liberación de Citoquinas/virología , Citocinas/antagonistas & inhibidores , Citocinas/sangre , Citocinas/inmunología , Humanos , Internet , Sistema Calicreína-Quinina/efectos de los fármacos , Sistema Calicreína-Quinina/inmunología , Pandemias , Peptidil-Dipeptidasa A/metabolismo , Neumonía Viral/sangre , Neumonía Viral/diagnóstico , Neumonía Viral/epidemiología , Alveolos Pulmonares/inmunología , Alveolos Pulmonares/patología , SARS-CoV-2 , Índice de Severidad de la Enfermedad , Transducción de Señal/efectos de los fármacos , Transducción de Señal/inmunología , Glicoproteína de la Espiga del Coronavirus/inmunología , Glicoproteína de la Espiga del Coronavirus/metabolismo , Factores de Tiempo , Tiempo de Tratamiento , Tratamiento Farmacológico de COVID-19RESUMEN
The mammalian small intestine epithelium harbors a peculiar population of CD4+CD8αα+ T cells that are derived from mature CD4+ T cells through reprogramming of lineage-specific transcription factors. CD4+CD8αα+ T cells occupy a unique niche in T cell biology because they exhibit mixed phenotypes and functional characteristics of both CD4+ helper and CD8+ cytotoxic T cells. The molecular pathways driving their generation are not fully mapped. However, recent studies demonstrate the unique role of the commensal gut microbiota as well as distinct cytokine and chemokine requirements in the differentiation and survival of these cells. We review the established and newly identified factors involved in the generation of CD4+CD8αα+ intraepithelial lymphocytes (IELs) and place them in the context of the molecular machinery that drives their phenotypic and functional differentiation.
Asunto(s)
Linfocitos Intraepiteliales , Humanos , Animales , Diferenciación Celular , Factores de Transcripción/metabolismo , Linfocitos T Citotóxicos , Linfocitos T CD8-positivos , Mucosa Intestinal/metabolismo , Receptores de Antígenos de Linfocitos T alfa-beta/metabolismo , MamíferosRESUMEN
The study of 5-hydroxylmethylcytosines (5hmC) has been hampered by the lack of a method to map it at single-base resolution on a genome-wide scale. Affinity purification-based methods cannot precisely locate 5hmC nor accurately determine its relative abundance at each modified site. We here present a genome-wide approach, Tet-assisted bisulfite sequencing (TAB-Seq), that when combined with traditional bisulfite sequencing can be used for mapping 5hmC at base resolution and quantifying the relative abundance of 5hmC as well as 5mC. Application of this method to embryonic stem cells not only confirms widespread distribution of 5hmC in the mammalian genome but also reveals sequence bias and strand asymmetry at 5hmC sites. We observe high levels of 5hmC and reciprocally low levels of 5mC near but not on transcription factor-binding sites. Additionally, the relative abundance of 5hmC varies significantly among distinct functional sequence elements, suggesting different mechanisms for 5hmC deposition and maintenance.
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Citosina/análogos & derivados , Estudio de Asociación del Genoma Completo , Análisis de Secuencia de ADN/métodos , 5-Metilcitosina/análisis , Animales , Citosina/análisis , Células Madre Embrionarias/metabolismo , Epigenómica , Regulación de la Expresión Génica , Genoma Humano , Humanos , RatonesRESUMEN
Fragile X syndrome (FXS) is the most common genetic cause of autism spectrum disorder engendered by transcriptional silencing of the fragile X messenger ribonucleoprotein 1 (FMR1) gene. Given the early onset of behavioral and molecular changes, it is imperative to know the optimal timing for therapeutic intervention. Case reports documented benefits of metformin treatment in FXS children between 2 and 14 y old. In this study, we administered metformin from birth to Fmr1-/y mice which corrected up-regulated mitogen-2 activated protein kinase/extracellular signal-regulated kinase and mammalian/mechanistic target of rapamycin complex 1 signaling pathways and specific synaptic mRNA-binding targets of FMRP. Metformin rescued increased number of calls in ultrasonic vocalization and repetitive behavior in Fmr1-/y mice. Our findings demonstrate that in mice, early-in-life metformin intervention is effective in treating FXS pathophysiology.
Asunto(s)
Proteína de la Discapacidad Intelectual del Síndrome del Cromosoma X Frágil , Síndrome del Cromosoma X Frágil , Metformina , Metformina/farmacología , Metformina/uso terapéutico , Síndrome del Cromosoma X Frágil/tratamiento farmacológico , Síndrome del Cromosoma X Frágil/genética , Síndrome del Cromosoma X Frágil/fisiopatología , Síndrome del Cromosoma X Frágil/metabolismo , Animales , Proteína de la Discapacidad Intelectual del Síndrome del Cromosoma X Frágil/genética , Proteína de la Discapacidad Intelectual del Síndrome del Cromosoma X Frágil/metabolismo , Ratones , Masculino , Ratones Noqueados , Diana Mecanicista del Complejo 1 de la Rapamicina/metabolismo , Modelos Animales de Enfermedad , Transducción de Señal/efectos de los fármacosRESUMEN
The integrated stress response (ISR), a pivotal protein homeostasis network, plays a critical role in the formation of long-term memory (LTM). The precise mechanism by which the ISR controls LTM is not well understood. Here, we report insights into how the ISR modulates the mnemonic process by using targeted deletion of the activating transcription factor 4 (ATF4), a key downstream effector of the ISR, in various neuronal and non-neuronal cell types. We found that the removal of ATF4 from forebrain excitatory neurons (but not from inhibitory neurons, cholinergic neurons, or astrocytes) enhances LTM formation. Furthermore, the deletion of ATF4 in excitatory neurons lowers the threshold for the induction of long-term potentiation, a cellular model for LTM. Transcriptomic and proteomic analyses revealed that ATF4 deletion in excitatory neurons leads to upregulation of components of oxidative phosphorylation pathways, which are critical for ATP production. Thus, we conclude that ATF4 functions as a memory repressor selectively within excitatory neurons.
Asunto(s)
Factor de Transcripción Activador 4 , Memoria a Largo Plazo , Neuronas , Animales , Ratones , Factor de Transcripción Activador 4/metabolismo , Factor de Transcripción Activador 4/genética , Astrocitos/metabolismo , Potenciación a Largo Plazo , Memoria a Largo Plazo/fisiología , Ratones Noqueados , Neuronas/metabolismo , Prosencéfalo/metabolismo , MasculinoRESUMEN
Lineage fate in the thymus is determined by mutually exclusive expression of the transcription factors ThPOK and Runx3, with ThPOK imposing the CD4(+) lineage fate and Runx3 promoting the CD8(+) lineage fate. While it is known that cytokine signals induce thymocytes to express Runx3, it is not known how ThPOK prevents thymocytes from expressing Runx3 and adopting the CD8(+) lineage fate, nor is it understood why ThPOK itself imposes the CD4(+) lineage fate on thymocytes. We now report that genes encoding members of the SOCS (suppressor of cytokine signaling) family are critical targets of ThPOK and that their induction by ThPOK represses Runx3 expression and promotes the CD4(+) lineage fate. Thus, induction of SOCS-encoding genes is the main mechanism by which ThPOK imposes the CD4(+) lineage fate in the thymus.
Asunto(s)
Linfocitos T CD4-Positivos/fisiología , Linaje de la Célula , Subunidad alfa 3 del Factor de Unión al Sitio Principal/fisiología , Proteínas Supresoras de la Señalización de Citocinas/genética , Factores de Transcripción/fisiología , Animales , Linfocitos T CD8-positivos/fisiología , Ratones , Ratones Endogámicos C57BLRESUMEN
Activation of class I phosphatidylinositol 3-kinase (PI3K) leads to formation of phosphatidylinositol-3,4,5-trisphophate (PIP3) and phosphatidylinositol-3,4-bisphophate (PI34P2), which spatiotemporally coordinate and regulate a myriad of cellular processes. By simultaneous quantitative imaging of PIP3 and PI34P2 in live cells, we here show that they have a distinctively different spatiotemporal distribution and history in response to growth factor stimulation, which allows them to selectively induce the membrane recruitment and activation of Akt isoforms. PI34P2 selectively activates Akt2 at both the plasma membrane and early endosomes, whereas PIP3 selectively stimulates Akt1 and Akt3 exclusively at the plasma membrane. These spatiotemporally distinct activation patterns of Akt isoforms provide a mechanism for their differential regulation of downstream signaling molecules. Collectively, our studies show that different spatiotemporal dynamics of PIP3 and PI34P2 and their ability to selectively activate key signaling proteins allow them to mediate class I PI3K signaling pathways in a spatiotemporally specific manner.
Asunto(s)
Imagen Óptica/métodos , Fosfatos de Fosfatidilinositol/fisiología , Imagen Individual de Molécula/métodos , Animales , Línea Celular , Membrana Celular , Humanos , Fosfatos de Inositol , Ratones , Fosfatidilinositol 3-Quinasas/metabolismo , Fosfatidilinositol 3-Quinasas/fisiología , Fosfatos de Fosfatidilinositol/metabolismo , Fosfatidilinositoles , Isoformas de Proteínas , Transporte de Proteínas , Proteínas Proto-Oncogénicas c-akt/metabolismo , Transducción de SeñalRESUMEN
mRNA translation initiation plays a critical role in learning and memory. The eIF4F complex, composed of the cap-binding protein eIF4E, ATP-dependent RNA helicase eIF4A, and scaffolding protein eIF4G, is a pivotal factor in the mRNA translation initiation process. eIF4G1, the major paralogue of the three eIF4G family members, is indispensable for development, but its function in learning and memory is unknown. To study the role of eIF4G1 in cognition, we used an eIF4G1 haploinsufficient (eIF4G1-1D) mouse model. The axonal arborization of eIF4G1-1D primary hippocampal neurons was significantly disrupted, and the mice displayed impairment in hippocampus-dependent learning and memory. Translatome analysis showed that the translation of mRNAs encoding proteins of the mitochondrial oxidative phosphorylation (OXPHOS) system was decreased in the eIF4G1-1D brain, and OXPHOS was decreased in eIF4G1-silenced cells. Thus, eIF4G1-mediated mRNA translation is crucial for optimal cognitive function, which is dependent on OXPHOS and neuronal morphogenesis.
Asunto(s)
Factor 4G Eucariótico de Iniciación , Fosforilación Oxidativa , Animales , Ratones , ARN Mensajero , Iniciación de la Cadena Peptídica Traduccional , Morfogénesis , ADN HelicasasRESUMEN
Amyotrophic lateral sclerosis (ALS) is a debilitating neurodegenerative disorder marked by progressive motor neuron degeneration and muscle denervation. A recent transcriptomic study integrating a wide range of human ALS samples revealed that the upregulation of p53, a downstream target of inflammatory stress, is commonly detected in familial and sporadic ALS cases by a mechanism linked to a transactive response DNA-binding protein 43 (TDP-43) dysfunction. In this study, we show that prolonged interferon-gamma (IFNγ) treatment of human induced pluripotent stem cell-derived spinal motor neurons results in a severe cytoplasmic aggregation of TDP-43. TDP-43 dysfunction resulting from either IFNγ exposure or an ALS-associated TDP-43 mutation was associated with the activation of the p53 pathway. This was accompanied by the hyperactivation of neuronal firing, followed by the complete loss of their electrophysiological function. Through a comparative single-cell transcriptome analysis, we have identified significant alterations in ALS-associated genes in motor neurons exposed to IFNγ, implicating their direct involvement in ALS pathology. Interestingly, IFNγ was found to induce significant levels of programmed death-ligand 1 (PD-L1) expression in motor neurons without affecting the levels of any other immune checkpoint proteins. This finding suggests a potential role of excessive PD-L1 expression in ALS development, given that PD-L1 was recently reported to impair neuronal firing ability in mice. Our findings suggest that exposing motor neurons to IFNγ could directly derive ALS pathogenesis, even without the presence of the inherent genetic mutation or functional glia component. Furthermore, this study provides a comprehensive list of potential candidate genes for future immunotherapeutic targets with which to treat sporadic forms of ALS, which account for 90% of all reported cases.
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Esclerosis Amiotrófica Lateral , Células Madre Pluripotentes Inducidas , Animales , Humanos , Ratones , Esclerosis Amiotrófica Lateral/genética , Esclerosis Amiotrófica Lateral/metabolismo , Esclerosis Amiotrófica Lateral/patología , Antígeno B7-H1/metabolismo , Biomarcadores , Proteínas de Unión al ADN/genética , Células Madre Pluripotentes Inducidas/metabolismo , Interferón gamma/metabolismo , Interferón gamma/farmacología , Neuronas Motoras/efectos de los fármacos , Neuronas Motoras/metabolismo , Neuronas Motoras/patología , Proteína p53 Supresora de Tumor/metabolismoRESUMEN
Systems biology can be defined as the study of a biological process in which all of the relevant components are investigated together in parallel to discover the mechanism. Although the approach is not new, it has come to the forefront as a result of genome sequencing projects completed in the first few years of the current century. It has elements of large-scale data acquisition (chiefly next-generation sequencing-based methods and protein mass spectrometry) and large-scale data analysis (big data integration and Bayesian modeling). Here we discuss these methodologies and show how they can be applied to understand the downstream effects of GPCR signaling, specifically looking at how the neurohypophyseal peptide hormone vasopressin, working through the V2 receptor and PKA activation, regulates the water channel aquaporin-2. The emerging picture provides a detailedframework for understanding the molecular mechanisms involved in water balance disorders, pointing the way to improved treatment of both polyuric disorders and water-retention disorders causing dilutional hyponatremia.
Asunto(s)
Receptores de Vasopresinas , Desequilibrio Hidroelectrolítico , Acuaporina 2/metabolismo , Teorema de Bayes , Humanos , Receptores de Vasopresinas/genética , Receptores de Vasopresinas/metabolismo , Biología de SistemasRESUMEN
The maintenance of naive CD8(+) T cells is necessary for lifelong immunocompetence but for unknown reasons requires signaling via both interleukin 7 (IL-7) and the T cell antigen receptor (TCR). We now report that naive CD8(+) T cells required IL-7 signaling to be intermittent, not continuous, because prolonged IL-7 signaling induced naive CD8(+) T cells to proliferate, produce interferon-γ (IFN-γ) and undergo IFN-γ-triggered cell death. Homeostatic engagement of the TCR interrupted IL-7 signaling and thereby supported the survival and quiescence of CD8(+) T cells. However, CD8(+) T cells with insufficient TCR affinity for self ligands received prolonged IL-7 signaling and died during homeostasis. In this study we identified regulation of the duration of IL-7 signaling by homeostatic engagement of the TCR as the basis for in vivo CD8(+) T cell homeostasis.
Asunto(s)
Linfocitos T CD8-positivos/inmunología , Homeostasis/inmunología , Interleucina-7/genética , Receptores de Antígenos de Linfocitos T/genética , Transducción de Señal/inmunología , Animales , Linfocitos T CD8-positivos/citología , Muerte Celular/inmunología , Proliferación Celular , Supervivencia Celular/inmunología , Regulación de la Expresión Génica , Interferón gamma/biosíntesis , Interferón gamma/inmunología , Interleucina-7/inmunología , Activación de Linfocitos , Ratones , Ratones Transgénicos , Receptores de Antígenos de Linfocitos T/inmunología , Factores de TiempoRESUMEN
BACKGROUND AND AIMS: In obesity, depletion of KCs expressing CRIg (complement receptor of the Ig superfamily) leads to microbial DNA accumulation, which subsequently triggers tissue inflammation and insulin resistance. However, the mechanism underlying obesity-mediated changes in KC complement immune functions is largely unknown. APPROACH AND RESULTS: Using KC-specific deactivated Cas9 transgenic mice treated with guide RNA, we assessed the effects of restoring CRIg or the serine/arginine-rich splicing factor 3 (SRSF3) abundance on KC functions and metabolic phenotypes in obese mice. The impacts of weight loss on KC responses were evaluated in a diet switch mouse model. The role of SRSF3 in regulating KC functions was also evaluated using KC-specific SRSF3 knockout mice. Here, we report that overexpression of CRIg in KCs of obese mice protects against bacterial DNA accumulation in metabolic tissues. Mechanistically, SRSF3 regulates CRIg expression, which is essential for maintaining the CRIg+ KC population. During obesity, SRSF3 expression decreases, but it is restored with weight loss through a diet switch, normalizing CRIg+ KCs. KC SRSF3 is also repressed in obese human livers. Lack of SRSF3 in KCs in lean and obese mice decreases their CRIg+ population, impairing metabolic parameters. During the diet switch, the benefits of weight loss are compromised due to SRSF3 deficiency. Conversely, SRSF3 overexpression in obese mice preserves CRIg+ KCs and improves metabolic responses. CONCLUSIONS: Restoring SRSF3 abundance in KCs offers a strategy against obesity-associated tissue inflammation and insulin resistance by preventing bacterial DNA accumulation.
Asunto(s)
Resistencia a la Insulina , Macrófagos del Hígado , Obesidad , Factores de Empalme Serina-Arginina , Animales , Factores de Empalme Serina-Arginina/metabolismo , Factores de Empalme Serina-Arginina/genética , Obesidad/metabolismo , Ratones , Macrófagos del Hígado/metabolismo , Humanos , Masculino , Ratones Transgénicos , Ratones Noqueados , Modelos Animales de Enfermedad , Ratones Endogámicos C57BLRESUMEN
During in vitro culture, human pluripotent stem cells (hPSCs) often acquire survival advantages characterized by decreased susceptibility to mitochondrial cell death, known as "culture adaptation." This adaptation is associated with genetic and epigenetic abnormalities, including TP53 mutations, copy number variations, trisomy, and methylation changes. Understanding the molecular mechanisms underlying this acquired survival advantage is crucial for safe hPSC-based cell therapies. Through transcriptome and methylome analysis, we discovered that the epigenetic repression of CHCHD2, a mitochondrial protein, is a common occurrence during in vitro culture using enzymatic dissociation. We confirmed this finding through genetic perturbation and reconstitution experiments in normal human embryonic stem cells (hESCs). Loss of CHCHD2 expression conferred resistance to single cell dissociation-induced cell death, a common stress encountered during in vitro culture. Importantly, we found that the downregulation of CHCHD2 significantly attenuates the activity of Rho-associated protein kinase (ROCK), which is responsible for inducing single cell death in hESCs. This suggests that hESCs may survive routine enzyme-based cell dissociation by downregulating CHCHD2 and thereby attenuating ROCK activity. These findings provide insights into the mechanisms by which hPSCs acquire survival advantages and adapt to in vitro culture conditions.
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Células Madre Embrionarias Humanas , Células Madre Pluripotentes , Humanos , Línea Celular , Represión Epigenética , Variaciones en el Número de Copia de ADN , Células Madre Embrionarias Humanas/metabolismo , Diferenciación Celular , Supervivencia Celular , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismoRESUMEN
The core plant microprocessor consists of DICER-LIKE 1 (DCL1), SERRATE (SE), and HYPONASTIC LEAVES 1 (HYL1) and plays a pivotal role in microRNA (miRNA) biogenesis. However, the proteolytic regulation of each component remains elusive. Here, we show that HYL1-CLEAVAGE SUBTILASE 1 (HCS1) is a cytoplasmic protease for HYL1-destabilization. HCS1-excessiveness reduces HYL1 that disrupts miRNA biogenesis, while HCS1-deficiency accumulates HYL1. Consistently, we identified the HYL1K154A mutant that is insensitive to the proteolytic activity of HCS1, confirming the importance of HCS1 in HYL1 proteostasis. Moreover, HCS1-activity is regulated by light/dark transition. Under light, cytoplasmic CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1) E3 ligase suppresses HCS1-activity. COP1 sterically inhibits HCS1 by obstructing HYL1 access into the catalytic sites of HCS1. In contrast, darkness unshackles HCS1-activity for HYL1-destabilization due to nuclear COP1 relocation. Overall, the COP1-HYL1-HCS1 network may integrate two essential cellular pathways: the miRNA-biogenetic pathway and light signaling pathway.
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Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , MicroARNs/metabolismo , Procesamiento Postranscripcional del ARN/fisiología , Proteínas de Ciclo Celular/metabolismo , Núcleo Celular/metabolismo , Regulación de la Expresión Génica de las Plantas/fisiología , Hojas de la Planta/metabolismo , Proteínas de Unión al ARN/metabolismo , Ubiquitina-Proteína Ligasas/metabolismoRESUMEN
Viruses evade the innate immune response by suppressing the production or activity of cytokines such as type I interferons (IFNs). Here we report the discovery of a mechanism by which the SARS-CoV-2 virus coopts an intrinsic cellular machinery to suppress the production of the key immunostimulatory cytokine IFN-ß. We reveal that the SARS-CoV-2 encoded nonstructural protein 2 (NSP2) directly interacts with the cellular GIGYF2 protein. This interaction enhances the binding of GIGYF2 to the mRNA cap-binding protein 4EHP, thereby repressing the translation of the Ifnb1 mRNA. Depletion of GIGYF2 or 4EHP significantly enhances IFN-ß production, which inhibits SARS-CoV-2 replication. Our findings reveal a target for rescuing the antiviral innate immune response to SARS-CoV-2 and other RNA viruses.