RESUMEN
Cytokines are secreted or otherwise released polypeptide factors that exert autocrine and/or paracrine actions, with most cytokines acting in the immune and/or hematopoietic system. They are typically pleiotropic, controlling development, cell growth, survival, and/or differentiation. Correspondingly, cytokines are clinically important, and augmenting or attenuating cytokine signals can have deleterious or therapeutic effects. Besides physiological fine-tuning of cytokine signals, altering the nature or potency of the signal can be important in pathophysiological responses and can also provide novel therapeutic approaches. Here, we give an overview of cytokines, their signaling and actions, and the physiological mechanisms and pharmacologic strategies to fine-tune their actions. In particular, the differential utilization of STAT proteins by a single cytokine or by different cytokines and STAT dimerization versus tetramerization are physiological mechanisms of fine-tuning, whereas anticytokine and anticytokine receptor antibodies and cytokines with altered activities, including cytokine superagonists, partial agonists, and antagonists, represent new ways of fine-tuning cytokine signals.
Asunto(s)
Citocinas/metabolismo , Inmunoterapia/tendencias , Animales , Citocinas/genética , Humanos , Inmunidad Humoral , Inmunomodulación , Multimerización de Proteína , Factores de Transcripción STAT/metabolismo , Transducción de Señal/inmunologíaRESUMEN
Crustal accretion at mid-ocean ridges governs the creation and evolution of the oceanic lithosphere. Generally accepted models1-4 of passive mantle upwelling and melting predict notably decreased crustal thickness at a spreading rate of less than 20 mm year-1. We conducted the first, to our knowledge, high-resolution ocean-bottom seismometer (OBS) experiment at the Gakkel Ridge in the Arctic Ocean and imaged the crustal structure of the slowest-spreading ridge on the Earth. Unexpectedly, we find that crustal thickness ranges between 3.3 km and 8.9 km along the ridge axis and it increased from about 4.5 km to about 7.5 km over the past 5 Myr in an across-axis profile. The highly variable crustal thickness and relatively large average value does not align with the prediction of passive mantle upwelling models. Instead, it can be explained by a model of buoyant active mantle flow driven by thermal and compositional density changes owing to melt extraction. The influence of active versus passive upwelling is predicted to increase with decreasing spreading rate. The process of active mantle upwelling is anticipated to be primarily influenced by mantle temperature and composition. This implies that the observed variability in crustal accretion, which includes notably varied crustal thickness, is probably an inherent characteristic of ultraslow-spreading ridges.
RESUMEN
It remains unclear whether activated inflammatory macrophages can adopt features of tissue-resident macrophages, or what mechanisms might mediate such a phenotypic conversion. Here we show that vitamin A is required for the phenotypic conversion of interleukin 4 (IL-4)-activated monocyte-derived F4/80intCD206+PD-L2+MHCII+ macrophages into macrophages with a tissue-resident F4/80hiCD206-PD-L2-MHCII-UCP1+ phenotype in the peritoneal cavity of mice and during the formation of liver granulomas in mice infected with Schistosoma mansoni. The phenotypic conversion of F4/80intCD206+ macrophages into F4/80hiCD206- macrophages was associated with almost complete remodeling of the chromatin landscape, as well as alteration of the transcriptional profiles. Vitamin A-deficient mice infected with S. mansoni had disrupted liver granuloma architecture and increased mortality, which indicates that failure to convert macrophages from the F4/80intCD206+ phenotype to F4/80hiCD206- may lead to dysregulated inflammation during helminth infection.
Asunto(s)
Granuloma/inmunología , Hígado/inmunología , Macrófagos/inmunología , Esquistosomiasis mansoni/inmunología , Deficiencia de Vitamina A/inmunología , Animales , Antígenos de Diferenciación/metabolismo , Citometría de Flujo , Antígenos de Histocompatibilidad Clase II/metabolismo , Interleucina-4/inmunología , Lectinas Tipo C/metabolismo , Hígado/patología , Macrófagos/efectos de los fármacos , Macrófagos/metabolismo , Macrófagos Alveolares/efectos de los fármacos , Macrófagos Alveolares/inmunología , Macrófagos Alveolares/metabolismo , Receptor de Manosa , Lectinas de Unión a Manosa/metabolismo , Ratones , Cavidad Peritoneal/citología , Proteína 2 Ligando de Muerte Celular Programada 1/metabolismo , Reacción en Cadena en Tiempo Real de la Polimerasa , Receptores de Superficie Celular/metabolismo , Schistosoma mansoni , Esquistosomiasis mansoni/patología , Tretinoina/farmacología , Proteína Desacopladora 1/metabolismo , Vitaminas/farmacologíaRESUMEN
T cell responses are guided by cytokines that induce transcriptional regulators, which ultimately control differentiation of effector and memory T cells. However, it is unknown how the activities of these molecular regulators are coordinated and integrated during the differentiation process. Using genetic approaches and transcriptional profiling of antigen-specific CD8(+) T cells, we reveal a common program of effector differentiation that is regulated by IL-2 and IL-12 signaling and the combined activities of the transcriptional regulators Blimp-1 and T-bet. The loss of both T-bet and Blimp-1 leads to abrogated cytotoxic function and ectopic IL-17 production in CD8(+) T cells. Overall, our data reveal two major overlapping pathways of effector differentiation governed by the availability of Blimp-1 and T-bet and suggest a model for cytokine-induced transcriptional changes that combine, quantitatively and qualitatively, to promote robust effector CD8(+) T cell differentiation.
Asunto(s)
Linfocitos T CD8-positivos/inmunología , Diferenciación Celular/inmunología , Interleucina-12/inmunología , Interleucina-2/inmunología , Proteínas de Dominio T Box/inmunología , Factores de Transcripción/inmunología , Animales , Infecciones por Arenaviridae/inmunología , Inmunoprecipitación de Cromatina , Citocinas/inmunología , Citometría de Flujo , Perfilación de la Expresión Génica , Subtipo H1N1 del Virus de la Influenza A , Interleucina-17/inmunología , Virus de la Coriomeningitis Linfocítica , Ratones , Infecciones por Orthomyxoviridae/inmunología , Factor 1 de Unión al Dominio 1 de Regulación Positiva , Reacción en Cadena en Tiempo Real de la Polimerasa , Factor de Transcripción STAT4/inmunología , Factor de Transcripción STAT5/inmunología , Análisis de Secuencia de ARN , Transducción de SeñalRESUMEN
The common cytokine receptor γ chain, γc, is a component of the receptors for interleukin-2 (IL-2), IL-4, IL-7, IL-9, IL-15, and IL-21. Mutation of the gene encoding γc results in X-linked severe combined immunodeficiency in humans, and γc family cytokines collectively regulate development, proliferation, survival, and differentiation of immune cells. Here, we review the basic biology of these cytokines, highlighting mechanisms of signaling and gene regulation that have provided insights for immunodeficiency, autoimmunity, allergic diseases, and cancer. Moreover, we discuss how studies of this family stimulated the development of JAK3 inhibitors and present an overview of current strategies targeting these pathways in the clinic, including novel antibodies, antagonists, and partial agonists. The diverse roles of these cytokines on a range of immune cells have important therapeutic implications.
Asunto(s)
Citocinas/clasificación , Subunidad gamma Común de Receptores de Interleucina/genética , Familia de Multigenes/inmunología , Animales , Enfermedades Autoinmunes/genética , Enfermedades Autoinmunes/inmunología , Citocinas/genética , Citocinas/inmunología , Evolución Molecular , Regulación de la Expresión Génica , Terapia Genética , Humanos , Síndromes de Inmunodeficiencia/inmunología , Síndromes de Inmunodeficiencia/terapia , Janus Quinasa 3/antagonistas & inhibidores , Quinasas Janus/antagonistas & inhibidores , Quinasas Janus/fisiología , Subgrupos Linfocitarios/inmunología , Ratones , Terapia Molecular Dirigida , Familia de Multigenes/genética , Neoplasias/genética , Neoplasias/inmunología , Subunidades de Proteína , Factores de Transcripción STAT/fisiología , Transducción de Señal , Investigación Biomédica Traslacional , Enfermedades por Inmunodeficiencia Combinada Ligada al Cromosoma X/genética , Enfermedades por Inmunodeficiencia Combinada Ligada al Cromosoma X/inmunología , Enfermedades por Inmunodeficiencia Combinada Ligada al Cromosoma X/terapiaRESUMEN
T cell dysfunction is a characteristic feature of chronic viral infection and cancer. Recent studies in chronic lymphocytic choriomeningitis virus (LCMV) infection have defined a PD-1+ Tcf-1+ CD8+ T cell subset capable of self-renewal and differentiation into more terminally differentiated cells that downregulate Tcf-1 and express additional inhibitory molecules such as Tim3. Here, we demonstrated that expression of the glycoprotein CD101 divides this terminally differentiated population into two subsets. Stem-like Tcf-1+ CD8+ T cells initially differentiated into a transitory population of CD101-Tim3+ cells that later converted into CD101+ Tim3+ cells. Recently generated CD101-Tim3+ cells proliferated in vivo, contributed to viral control, and were marked by an effector-like transcriptional signature including expression of the chemokine receptor CX3CR1, pro-inflammatory cytokines, and granzyme B. PD-1 pathway blockade increased the numbers of CD101-Tim3+ CD8+ T cells, suggesting that these newly generated transitional cells play a critical role in PD-1-based immunotherapy.
Asunto(s)
Antígenos CD/metabolismo , Linfocitos T CD8-positivos/inmunología , Coriomeningitis Linfocítica/inmunología , Virus de la Coriomeningitis Linfocítica/inmunología , Receptor de Muerte Celular Programada 1/metabolismo , Animales , Biomarcadores/metabolismo , Receptor 1 de Quimiocinas CX3C/genética , Receptor 1 de Quimiocinas CX3C/metabolismo , Femenino , Granzimas/genética , Granzimas/metabolismo , Receptor 2 Celular del Virus de la Hepatitis A/biosíntesis , Factor Nuclear 1-alfa del Hepatocito/genética , Factor Nuclear 1-alfa del Hepatocito/metabolismo , Coriomeningitis Linfocítica/virología , Masculino , Ratones , Ratones Endogámicos C57BL , Receptor de Muerte Celular Programada 1/genéticaRESUMEN
Synthetic receptor signalling has the potential to endow adoptively transferred T cells with new functions that overcome major barriers in the treatment of solid tumours, including the need for conditioning chemotherapy1,2. Here we designed chimeric receptors that have an orthogonal IL-2 receptor extracellular domain (ECD) fused with the intracellular domain (ICD) of receptors for common γ-chain (γc) cytokines IL-4, IL-7, IL-9 and IL-21 such that the orthogonal IL-2 cytokine elicits the corresponding γc cytokine signal. Of these, T cells that signal through the chimeric orthogonal IL-2Rß-ECD-IL-9R-ICD (o9R) are distinguished by the concomitant activation of STAT1, STAT3 and STAT5 and assume characteristics of stem cell memory and effector T cells. Compared to o2R T cells, o9R T cells have superior anti-tumour efficacy in two recalcitrant syngeneic mouse solid tumour models of melanoma and pancreatic cancer and are effective even in the absence of conditioning lymphodepletion. Therefore, by repurposing IL-9R signalling using a chimeric orthogonal cytokine receptor, T cells gain new functions, and this results in improved anti-tumour activity for hard-to-treat solid tumours.
Asunto(s)
Tratamiento Basado en Trasplante de Células y Tejidos , Inmunoterapia Adoptiva , Subunidad gamma Común de Receptores de Interleucina , Neoplasias , Receptores de Interleucina-9 , Proteínas Recombinantes de Fusión , Linfocitos T , Animales , Tratamiento Basado en Trasplante de Células y Tejidos/métodos , Inmunoterapia Adoptiva/métodos , Subunidad gamma Común de Receptores de Interleucina/genética , Subunidad gamma Común de Receptores de Interleucina/inmunología , Interleucinas/genética , Interleucinas/inmunología , Melanoma/inmunología , Ratones , Neoplasias/genética , Neoplasias/inmunología , Neoplasias Pancreáticas/inmunología , Receptores de Interleucina-9/genética , Receptores de Interleucina-9/inmunología , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/inmunología , Factores de Transcripción STAT/metabolismo , Linfocitos T/inmunología , Linfocitos T/metabolismoRESUMEN
Combination therapy with PD-1 blockade and IL-2 is highly effective during chronic lymphocytic choriomeningitis virus infection1. Here we examine the underlying basis for this synergy. We show that PD-1 + IL-2 combination therapy, in contrast to PD-1 monotherapy, substantially changes the differentiation program of the PD-1+TCF1+ stem-like CD8+ T cells and results in the generation of transcriptionally and epigenetically distinct effector CD8+ T cells that resemble highly functional effector CD8+ T cells seen after an acute viral infection. The generation of these qualitatively superior CD8+ T cells that mediate viral control underlies the synergy between PD-1 and IL-2. Our results show that the PD-1+TCF1+ stem-like CD8+ T cells, also referred to as precursors of exhausted CD8+ T cells, are not fate-locked into the exhaustion program and their differentiation trajectory can be changed by IL-2 signals. These virus-specific effector CD8+ T cells emerging from the stem-like CD8+ T cells after combination therapy expressed increased levels of the high-affinity IL-2 trimeric (CD25-CD122-CD132) receptor. This was not seen after PD-1 blockade alone. Finally, we show that CD25 engagement with IL-2 has an important role in the observed synergy between IL-2 cytokine and PD-1 blockade. Either blocking CD25 with an antibody or using a mutated version of IL-2 that does not bind to CD25 but still binds to CD122 and CD132 almost completely abrogated the synergistic effects observed after PD-1 + IL-2 combination therapy. There is considerable interest in PD-1 + IL-2 combination therapy for patients with cancer2,3, and our fundamental studies defining the underlying mechanisms of how IL-2 synergizes with PD-1 blockade should inform these human translational studies.
Asunto(s)
Linfocitos T CD8-positivos , Interleucina-2 , Receptor de Muerte Celular Programada 1 , Linfocitos T CD8-positivos/citología , Linfocitos T CD8-positivos/efectos de los fármacos , Linfocitos T CD8-positivos/inmunología , Diferenciación Celular/efectos de los fármacos , Quimioterapia Combinada , Humanos , Subunidad gamma Común de Receptores de Interleucina , Interleucina-2/inmunología , Interleucina-2/farmacología , Interleucina-2/uso terapéutico , Subunidad alfa del Receptor de Interleucina-2 , Subunidad beta del Receptor de Interleucina-2 , Coriomeningitis Linfocítica/tratamiento farmacológico , Coriomeningitis Linfocítica/inmunología , Receptor de Muerte Celular Programada 1/antagonistas & inhibidores , Factor 1 de Transcripción de Linfocitos TRESUMEN
Soil salinity results in oxidative stress and heavy losses to crop production. The S-acylated protein SALT TOLERANCE RECEPTOR-LIKE CYTOPLASMIC KINASE 1 (STRK1) phosphorylates and activates CATALASE C (CatC) to improve rice (Oryza sativa L.) salt tolerance, but the molecular mechanism underlying its S-acylation involved in salt signal transduction awaits elucidation. Here, we show that the DHHC-type zinc finger protein DHHC09 S-acylates STRK1 at Cys5, Cys10, and Cys14 and promotes salt and oxidative stress tolerance by enhancing rice H2O2-scavenging capacity. This modification determines STRK1 targeting to the plasma membrane or lipid nanodomains and is required for its function. DHHC09 promotes salt signaling from STRK1 to CatC via transphosphorylation, and its deficiency impairs salt signal transduction. Our findings demonstrate that DHHC09 S-acylates and anchors STRK1 to the plasma membrane to promote salt signaling from STRK1 to CatC, thereby regulating H2O2 homeostasis and improving salt stress tolerance in rice. Moreover, overexpression of DHHC09 in rice mitigates grain yield loss under salt stress. Together, these results shed light on the mechanism underlying the role of S-acylation in RLK/RLCK-mediated salt signal transduction and provide a strategy for breeding highly salt-tolerant rice.
Asunto(s)
Oryza , Tolerancia a la Sal , Tolerancia a la Sal/genética , Oryza/metabolismo , Peróxido de Hidrógeno/metabolismo , Homeostasis , Dedos de Zinc , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismoRESUMEN
Adoptive transfer of antigen-specific T cells represents a major advance in cancer immunotherapy, with robust clinical outcomes in some patients1. Both the number of transferred T cells and their differentiation state are critical determinants of effective responses2,3. T cells can be expanded with T cell receptor (TCR)-mediated stimulation and interleukin-2, but this can lead to differentiation into effector T cells4,5 and lower therapeutic efficacy6, whereas maintenance of a more stem-cell-like state before adoptive transfer is beneficial7. Here we show that H9T, an engineered interleukin-2 partial agonist, promotes the expansion of CD8+ T cells without driving terminal differentiation. H9T led to altered STAT5 signalling and mediated distinctive downstream transcriptional, epigenetic and metabolic programs. In addition, H9T treatment sustained the expression of T cell transcription factor 1 (TCF-1) and promoted mitochondrial fitness, thereby facilitating the maintenance of a stem-cell-like state. Moreover, TCR-transgenic and chimeric antigen receptor-modified CD8+ T cells that were expanded with H9T showed robust anti-tumour activity in vivo in mouse models of melanoma and acute lymphoblastic leukaemia. Thus, engineering cytokine variants with distinctive properties is a promising strategy for creating new molecules with translational potential.
Asunto(s)
Linfocitos T CD8-positivos/citología , Linfocitos T CD8-positivos/efectos de los fármacos , Diferenciación Celular/efectos de los fármacos , Agonismo Parcial de Drogas , Interleucina-2/análogos & derivados , Interleucina-2/agonistas , Proteínas Mutantes/farmacología , Células Madre/efectos de los fármacos , Animales , Linfocitos T CD8-positivos/inmunología , Interleucina-2/química , Interleucina-2/genética , Melanoma/metabolismo , Ratones , Mitocondrias/efectos de los fármacos , Proteínas Mutantes/química , Proteínas Mutantes/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/metabolismo , Receptores de Antígenos de Linfocitos T/genética , Receptores de Antígenos de Linfocitos T/metabolismo , Factor de Transcripción STAT5/metabolismo , Células Madre/citología , Factor 1 de Transcripción de Linfocitos T/metabolismo , Investigación Biomédica TraslacionalRESUMEN
Accurate chromosome segregation, monitored by the spindle assembly checkpoint (SAC), is crucial for the production of euploid cells. Previous in vitro studies by us and others showed that Mad2, a core member of the SAC, performs a checkpoint function in oocyte meiosis. Here, through an oocyte-specific knockout approach in mouse, we reconfirmed that Mad2-deficient oocytes exhibit an accelerated metaphase-to-anaphase transition caused by premature degradation of securin and cyclin B1 and subsequent activation of separase in meiosis I. However, it was surprising that the knockout mice were completely fertile and the resulting oocytes were euploid. In the absence of Mad2, other SAC proteins, including BubR1, Bub3 and Mad1, were normally recruited to the kinetochores, which likely explains the balanced chromosome separation. Further studies showed that the chromosome separation in Mad2-null oocytes was particularly sensitive to environmental changes and, when matured in vitro, showed chromosome misalignment, lagging chromosomes, and aneuploidy with premature separation of sister chromatids, which was exacerbated at a lower temperature. We reveal for the first time that Mad2 is dispensable for proper chromosome segregation but acts to mitigate environmental stress in meiotic oocytes.
Asunto(s)
Proteínas de Ciclo Celular , Huso Acromático , Animales , Ratones , Proteínas de Ciclo Celular/metabolismo , Huso Acromático/metabolismo , Proteínas Mad2/genética , Proteínas Mad2/metabolismo , Segregación Cromosómica/genética , Oocitos/metabolismo , Cinetocoros/metabolismo , Meiosis/genéticaRESUMEN
Catalase (CAT) is often phosphorylated and activated by protein kinases to maintain hydrogen peroxide (H2O2) homeostasis and protect cells against stresses, but whether and how CAT is switched off by protein phosphatases remains inconclusive. Here, we identified a manganese (Mn2+)-dependent protein phosphatase, which we named PHOSPHATASE OF CATALASE 1 (PC1), from rice (Oryza sativa L.) that negatively regulates salt and oxidative stress tolerance. PC1 specifically dephosphorylates CatC at Ser-9 to inhibit its tetramerization and thus activity in the peroxisome. PC1 overexpressing lines exhibited hypersensitivity to salt and oxidative stresses with a lower phospho-serine level of CATs. Phosphatase activity and seminal root growth assays indicated that PC1 promotes growth and plays a vital role during the transition from salt stress to normal growth conditions. Our findings demonstrate that PC1 acts as a molecular switch to dephosphorylate and deactivate CatC and negatively regulate H2O2 homeostasis and salt tolerance in rice. Moreover, knockout of PC1 not only improved H2O2-scavenging capacity and salt tolerance but also limited rice grain yield loss under salt stress conditions. Together, these results shed light on the mechanisms that switch off CAT and provide a strategy for breeding highly salt-tolerant rice.
Asunto(s)
Oryza , Catalasa/genética , Catalasa/metabolismo , Oryza/metabolismo , Peróxido de Hidrógeno/metabolismo , Proteína Fosfatasa 1/metabolismo , Tolerancia a la Sal/genética , Homeostasis , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismoRESUMEN
The interleukin-4 (IL-4) cytokine plays a critical role in modulating immune homeostasis. Although there is great interest in harnessing this cytokine as a therapeutic in natural or engineered formats, the clinical potential of native IL-4 is limited by its instability and pleiotropic actions. Here, we design IL-4 cytokine mimetics (denoted Neo-4) based on a de novo engineered IL-2 mimetic scaffold and demonstrate that these cytokines can recapitulate physiological functions of IL-4 in cellular and animal models. In contrast with natural IL-4, Neo-4 is hyperstable and signals exclusively through the type I IL-4 receptor complex, providing previously inaccessible insights into differential IL-4 signaling through type I versus type II receptors. Because of their hyperstability, our computationally designed mimetics can directly incorporate into sophisticated biomaterials that require heat processing, such as three-dimensional-printed scaffolds. Neo-4 should be broadly useful for interrogating IL-4 biology, and the design workflow will inform targeted cytokine therapeutic development.
Asunto(s)
Citocinas , Interleucina-4 , Animales , Transducción de SeñalRESUMEN
Gustatory cortex (GC), a structure deeply involved in the making of consumption decisions, presumably performs this function by integrating information about taste, experiences, and internal states related to the animal's health, such as illness. Here, we investigated this assertion, examining whether illness is represented in GC activity, and how this representation impacts taste responses and behavior. We recorded GC single-neuron activity and local field potentials (LFPs) from healthy rats and rats made ill (via LiCl injection). We show (consistent with the extant literature) that the onset of illness-related behaviors arises contemporaneously with alterations in 7 to 12 Hz LFP power at approximately 12 min following injection. This process was accompanied by reductions in single-neuron taste response magnitudes and discriminability, and with enhancements in palatability-relatedness-a result reflecting the collapse of responses toward a simple "good-bad" code visible in the entire sample, but focused on a specific subset of GC neurons. Overall, our data show that a state (illness) that profoundly reduces consumption changes basic properties of the sensory cortical response to tastes, in a manner that can easily explain illness' impact on consumption.
Asunto(s)
Percepción del Gusto , Gusto , Animales , Corteza Cerebral/fisiología , Neuronas/fisiología , Ratas , Ratas Long-Evans , Gusto/fisiologíaRESUMEN
Our previous studies identified a population of stem cell-like proliferating myeloid cells within inflamed tissues that could serve as a reservoir for tissue macrophages to adopt different activation states depending on the microenvironment. By lineage-tracing cells derived from CX3CR1+ precursors in mice during infection and profiling by single-cell RNA sequencing, in this study, we identify a cluster of BIRC5+ myeloid cells that expanded in the liver during chronic infection with either the parasite Schistosoma mansoni or the bacterial pathogen Staphylococcus aureus. In the absence of tissue-damaging toxins, S. aureus infection does not elicit these BIRC5+ cells. Moreover, deletion of BIRC5 from CX3CR1-expressing cells results in improved survival during S. aureus infection. Hence the combination of single-cell RNA sequencing and genetic fate-mapping CX3CR1+ cells revealed a toxin-dependent pathogenic role for BIRC5 in myeloid cells during S. aureus infection.
Asunto(s)
Infecciones Estafilocócicas , Staphylococcus aureus , Ratones , Animales , Células Mieloides/patología , Análisis de la Célula Individual , Infecciones Estafilocócicas/microbiologíaRESUMEN
Lysine methylation is a conserved and dynamic regulatory posttranslational modification performed by lysine methyltransferases (KMTs). KMTs catalyze the transfer of mono-, di-, or tri-methyl groups to substrate proteins and play a critical regulatory role in all domains of life. To date, only one KMT has been identified in cyanobacteria. Here, we tested all of the predicted KMTs in the cyanobacterium Synechocystis sp. PCC 6803 (Synechocystis), and we biochemically characterized sll1526 that we termed cKMT1 (cyanobacterial lysine methyltransferase 1) and determined that it can catalyze lysine methylation both in vivo and in vitro. Loss of cKMT1 alters photosynthetic electron transfer in Synechocystis. We analyzed cKMT1-regulated methylation sites in Synechocystis using a timsTOF Pro instrument. We identified 305 class I lysine methylation sites within 232 proteins, and of these, 80 methylation sites in 58 proteins were hypomethylated in ΔcKMT1 cells. We further demonstrated that cKMT1 could methylate ferredoxin-NADP(+) oxidoreductase (FNR) and its potential sites of action on FNR were identified. Amino acid residues H118 and Y219 were identified as key residues in the putative active site of cKMT1 as indicated by structure simulation, site-directed mutagenesis, and KMT activity measurement. Using mutations that mimic the unmethylated forms of FNR, we demonstrated that the inability to methylate K139 residues results in a decrease in the redox activity of FNR and affects energy transfer in Synechocystis. Together, our study identified a new KMT in Synechocystis and elucidated a methylation-mediated molecular mechanism catalyzed by cKMT1 for the regulation of energy transfer in cyanobacteria.
Asunto(s)
Cianobacterias , Ferredoxinas , Synechocystis , Transferencia de Energía , Ferredoxina-NADP Reductasa/química , Ferredoxina-NADP Reductasa/genética , Ferredoxina-NADP Reductasa/metabolismo , Ferredoxinas/química , Ferredoxinas/metabolismo , Lisina , Metiltransferasas/metabolismo , NADP/metabolismo , Synechocystis/metabolismo , Cianobacterias/metabolismoRESUMEN
OBJECTIVE: Precancerous metaplasia transition to dysplasia poses a risk for subsequent intestinal-type gastric adenocarcinoma. However, the molecular basis underlying the transformation from metaplastic to cancerous cells remains poorly understood. DESIGN: An integrated analysis of genes associated with metaplasia, dysplasia was conducted, verified and characterised in the gastric tissues of patients by single-cell RNA sequencing and immunostaining. Multiple mouse models, including homozygous conditional knockout Klhl21-floxed mice, were generated to investigate the role of Klhl21 deletion in stemness, DNA damage and tumour formation. Mass-spectrometry-based proteomics and ribosome sequencing were used to elucidate the underlying molecular mechanisms. RESULTS: Kelch-like protein 21 (KLHL21) expression progressively decreased in metaplasia, dysplasia and cancer. Genetic deletion of Klhl21 enhances the rapid proliferation of Mist1+ cells and their descendant cells. Klhl21 loss during metaplasia facilitates the recruitment of damaged cells into the cell cycle via STAT3 signalling. Increased STAT3 activity was confirmed in cancer cells lacking KLHL21, boosting self-renewal and tumourigenicity. Mechanistically, the loss of KLHL21 promotes PIK3CB mRNA translation by stabilising the PABPC1-eIF4G complex, subsequently causing STAT3 activation. Pharmacological STAT3 inhibition by TTI-101 elicited anticancer effects, effectively impeding the transition from metaplasia to dysplasia. In patients with gastric cancer, low levels of KLHL21 had a shorter survival rate and a worse response to adjuvant chemotherapy. CONCLUSIONS: Our findings highlighted that KLHL21 loss triggers STAT3 reactivation through PABPC1-mediated PIK3CB translational activation, and targeting STAT3 can reverse preneoplastic metaplasia in KLHL21-deficient stomachs.
RESUMEN
Cyanobacteria are the oldest prokaryotic photoautotrophic microorganisms and have evolved complicated post-translational modification (PTM) machinery to respond to environmental stress. Lysine 2-hydroxyisobutyrylation (Khib) is a newly identified PTM that is reported to play important roles in diverse biological processes, however, its distribution and function in cyanobacteria have not been reported. Here, we performed the first systematic studies of Khib in a model cyanobacterium Synechococcus sp. strain PCC 7002 (Syn7002) using peptide prefractionation, pan-Khib antibody enrichment, and high-accuracy mass spectrometry (MS) analysis. A total of 1875 high-confidence Khib sites on 618 proteins were identified, and a large proportion of Khib sites are present on proteins in the cellular metabolism, protein synthesis, and photosynthesis pathways. Using site-directed mutagenesis and functional studies, we showed that Khib of glutaredoxin (Grx) affects the efficiency of the PS II reaction center and H2O2 resistance in Syn7002. Together, this study provides novel insights into the functions of Khib in cyanobacteria and suggests that reversible Khib may influence the stress response and photosynthesis in both cyanobacteria and plants.
Asunto(s)
Lisina , Procesamiento Proteico-Postraduccional , Synechococcus , Lisina/metabolismo , Synechococcus/metabolismo , Synechococcus/genética , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/genética , Peróxido de Hidrógeno/metabolismo , Glutarredoxinas/metabolismo , Glutarredoxinas/genética , Complejo de Proteína del Fotosistema II/metabolismo , Complejo de Proteína del Fotosistema II/genética , Mutagénesis Sitio-Dirigida , Fotosíntesis , Cianobacterias/metabolismo , Cianobacterias/genética , Espectrometría de MasasRESUMEN
Dual-atom catalysts (DACs) with paired active sites can provide unique intrinsic properties for heterogeneous catalysis, but the synergy of the active centers remains to be elucidated. Here, we develop a high-performance DAC with Zn1Co1 species anchored on nitrogen-doped carbon (Zn1Co1/NC) as the dominant active site for the propane dehydrogenation (PDH) reaction. It exhibits several times higher turnover frequency (TOF) of C3H8 conversion and enhanced C3H6 selectivity compared to Zn1/NC or Co1/NC with only a single-atom site. Various experimental and theoretical studies suggest that the enhanced PDH performance stems from the promoted activation of the C-H bond of C3H8 triggered by the electronic interaction between Zn1 and Co1 colligated by N species. Moreover, the dynamic sinking of the Zn1 site and rising of the Co1 site, together with the steric effect of the dissociated H species at the bridged N during the PDH reaction, provides a feasible channel for C3H6 desorption through the more exposed Co1 site, thereby boosting the selectivity. This work provides a promising strategy for designing robust hetero DACs to simultaneously increase activity and selectivity in the PDH reaction.
RESUMEN
Liver transplantation is an effective treatment for end-stage liver disease, acute liver failure, and primary hepatic malignancy. However, the limited availability of donor organs remains a challenge. Severe large-droplet fat (LDF) macrovesicular steatosis, characterized by cytoplasmic replacement with large fat vacuoles, can lead to liver transplant complications. Artificial intelligence models, such as segmentation and detection models, are being developed to detect LDF hepatocytes. The Segment-Anything Model, utilizing the DEtection TRansformer architecture, has the ability to segment objects without prior knowledge of size or shape. We investigated the Segment-Anything Model's potential to detect LDF hepatocytes in liver biopsies. Pathologist-annotated specimens were used to evaluate model performance. The model showed high sensitivity but compromised specificity due to similarities with other structures. Filtering algorithms were developed to improve specificity. Integration of the Segment-Anything Model with rule-based algorithms accurately detected LDF hepatocytes. Improved diagnosis and treatment of liver diseases can be achieved through advancements in artificial intelligence algorithms for liver histology analysis.