Phosphorylation of CREB affects its binding to high and low affinity sites

Cyclic AMP treatment of hepatoma cells leads to increased protein binding at the cyclic AMP response element (CRE) of the tyrosine aminotransferase (TAT) gene in vivo, as revealed by genomic footprinting, whereas no increase is observed at the CRE of the phosphoenolpyruvate carboxykinase (PEPCK) gene. Several criteria establish that the 43 kDa CREB protein is interacting with both of these sites. Two classes of CRE with different affinity for CREB are described. One class, including the TATCRE, is characterized by asymmetric and weak binding sites (CGTCA), whereas the second class containing symmetrical TGACGTCA sites shows a much higher binding affinity for CREB. Both classes show an increase in binding after phosphorylation of CREB by protein kinase A (PKA). An in vivo phosphorylation-dependent change in binding of CREB increases the occupancy of weak binding sites used for transactivation, such as the TATCRE, while high affinity sites may have constitutive binding of transcriptionally active and inactive CREB dimers, as demonstrated by in vivo footprinting at the PEPCK CRE. Thus, lower basal level and higher relative stimulation of transcription by cyclic AMP through low affinity CREs should result, allowing finely tuned control of gene activation

Phosphorylation of CREB affects its binding to high and low affinity sites

Cyclic AMP treatment of hepatoma cells leads to increased protein binding at the cyclic AMP response element (CRE) of the tyrosine aminotransferase (TAT) gene in vivo, as revealed by genomic footprinting, whereas no increase is observed at the CRE of the phosphoenolpyruvate carboxykinase (PEPCK) gene. Several criteria establish that the 43 kDa CREB protein is interacting with both of these sites. Two classes of CRE with different affinity for CREB are described. One class, including the TATCRE, is characterized by asymmetric and weak binding sites (CGTCA), whereas the second class containing symmetrical TGACGTCA sites shows a much higher binding affinity for CREB. Both classes show an increase in binding after phosphorylation of CREB by protein kinase A (PKA). An in vivo phosphorylation-dependent change in binding of CREB increases the occupancy of weak binding sites used for transactivation, such as the TATCRE, while high affinity sites may have constitutive binding of transcriptionally active and inactive CREB dimers, as demonstrated by in vivo footprinting at the PEPCK CRE. Thus, lower basal level and higher relative stimulation of transcription by cyclic AMP through low affinity CREs should result, allowing finely tuned control of gene activation

Carm1-arginine methylation of the transcription factor C/EBPα regulates transdifferentiation velocity

Developmental biology; Gene regulation; Transcription factorBiologia del desenvolupament; Regulació gènica; Factor de transcripcióBiología del desarrollo; Regulación génica; Factor de transcripciónHere, we describe how the speed of C/EBPα-induced B cell to macrophage transdifferentiation (BMT) can be regulated, using both mouse and human models. The identification of a mutant of C/EBPα (C/EBPαR35A) that greatly accelerates BMT helped to illuminate the mechanism. Thus, incoming C/EBPα binds to PU.1, an obligate partner expressed in B cells, leading to the release of PU.1 from B cell enhancers, chromatin closing and silencing of the B cell program. Released PU.1 redistributes to macrophage enhancers newly occupied by C/EBPα, causing chromatin opening and activation of macrophage genes. All these steps are accelerated by C/EBPαR35A, initiated by its increased affinity for PU.1. Wild-type C/EBPα is methylated by Carm1 at arginine 35 and the enzyme’s perturbations modulate BMT velocity as predicted from the observations with the mutant. Increasing the proportion of unmethylated C/EBPα in granulocyte/macrophage progenitors by inhibiting Carm1 biases the cell’s differentiation toward macrophages, suggesting that cell fate decision velocity and lineage directionality are closely linked processes.TG was supported by the Center for Genomic Regulation, Barcelona, the Spanish Ministry of Economy, Industry and Competitiveness, (Plan Estatal PID2019-109354GB-100), AGAUR (SGR 006713) and the 4D-Genome European Research Council Synergy grant. KSZ was supported by the NIH grant R01GM36477. We have used ChatGPT to improve parts of the text

The Homeobox Gene GBX2, a Target of the myb Oncogene, Mediates Autocrine Growth and Monocyte Differentiation

AbstractThe homeobox gene GBX2 was identified as a target gene of the v-Myb oncoprotein encoded by the avian myeloblastosis virus (AMV). GBX2 activation by c-Myb requires signal transduction emanating from the cell surface while the leukemogenic AMV v-Myb constitutively induces the GBX2 gene. Mutations in the DNA binding domain of AMV-Myb render it independent of signaling events and concomitantly abrogate the collaboration between Myb and CCAAT Enhancer Binding Proteins (C/EBP), which are involved in granulocyte differentiation. Ectopic expression of GBX2 in growth factor–dependent myeloblasts induces monocytic features and independence from exogenous cytokines, reflecting distinct features of AMV–transformed cells. Our results suggest that Myb or factors it interacts with contribute to hematopoietic lineage choice and differentiation in a signal transduction–dependent fashion

Cooperation between C/EBPα TBP/TFIIB and SWI/SNF recruiting domains is required for adipocyte differentiation

Chromatin remodeling is an important step in promoter activation during cellular lineage commitment and differentiation. We show that the ability of the C/EBPα transcription factor to direct adipocyte differentiation of uncommitted fibroblast precursors and to activate SWI/SNF-dependent myeloid-specific genes depends on a domain, C/EBPα transactivation element III (TE-III), that binds the SWI/SNF chromatin remodeling complex. TE-III collaborates with C/EBPα TBP/TFIIB interaction motifs during induction of adipogenesis and adipocyte-specific gene expression. These results indicate that C/EBPα acts as a lineage-instructive transcription factor through SWI/SNF-dependent modification of the chromatin structure of lineage-specific genes, followed by direct promoter activation via recruitment of the basal transcription–initiation complex, and provide a mechanism by which C/EBPα can mediate differentiation along multiple cellular lineages

Team consolidation, social integration and scientists’ research performance: An empirical study in the Biology and Biomedicine field

This is an author post-print (ie final draft post-refereeing) of the paper accepted for publication in Scientometrics 76 (3), 2008. The original publication is available at www.springerlink.com [http://www.springerlink.com/content/0138-9130]The effects of team consolidation and social integration on individual scientists’ activity and performance were investigated by analysing the relationships between these factors and scientists’ productivity, impact, collaboration patterns, participation in funded research projects and programs, contribution to the training of junior researchers, and prestige. Data were obtained from a survey of researchers ascribed to the Biology and Biomedicine area of the Spanish Council for Scientific Research, and from their curricula vitae. The results show that high levels of team consolidation and of integration of the scientist within his or her team are factors which might help create the most favourable social climate for research performance and productivity. Researchers who carried out their activity in a social climate characterized by these factors participated in more domestic research projects and supervised more doctoral dissertations than the rest of their colleagues. They were also more productive, as shown by the higher number of papers published in journals included in the Journal Citation Reports and the higher number of patents granted. These metrics are the main indicators taken into account in the evaluation of the research activity of Spanish scientists, and are therefore the activities that scientists invest the most energy in with a view to obtaining professional recognition. The results corroborate the importance of research teamwork, and draw attention to the importance of teamwork understood not as two or more scientists working together to solve a problem, but as a complex process involving interactions and interpersonal relations within a particular contextual framework.RESUMEN. Se investigan los efectos de la consolidación de los equipos y de la integración social de los individuos, sobre distintos aspectos de la actividad investigadora y el rendimiento de los científicos: productividad, impacto, pautas de colaboración, participación en programas y proyectos de I+D financiados, contribución a la formación de jóvenes investigadores y prestigio. Los datos proceden de una encuesta realizada a los investigadores adscritos al área de Biología y Biomedicina del Consejo Superior de Investigaciones Científicas, así como de sus curricula vitae. Los resultados muestran que elevados niveles de consolidación grupal y de integración de los científicos en el seno de sus equipos, son factores que pueden contribuir a crear el clima social más favorable para el rendimiento y la productividad científica. Los investigadores que desarrollaron su actividad en un clima social caracterizado por estos factores, participaron en un mayor número de más proyectos de investigación nacionales qy dirigieron más tesis doctorales, que el resto de sus colegas. Asimismo, fueron más productivos, tanto en número de artículos en revistas incluidas en el Journal Citation Reports como de patentes concedidas. Estos son los principales indicadores considerados a la hora de evaluar la actividad investigadora de los científicos españoles en este y otros campos científicos, y como consecuencia son las actividades a las que dedican mayor empeño, con el fin de conseguir mayor reconocimiento profesional de su trabajo. Los resultados corroboran la importancia del trabajo de investigación en equipo, y llaman la atención sobre la importancia del trabajo en equipo entendido no como dos o más científicos que trabajan juntos en la solución de un determinado problema, sino como un proceso complejo que implica interacciones y relaciones personales en el seno de un determinado marco contextual.The study reported in this paper was done as part of the research project titled ‘Consolidation and cohesion of CSIC research teams and their influence on the research activity and performance of their components’ (CSIC intramural project 200410E051) El estudio ha sido realizado en el marco del proyecto de investigación Consolidación y cohesión de los equipos de investigación del CSIC y su influencia sobre la actividad investigadora y el rendimiento de sus componentes. Área de Biología y Biomedicina' financiado por el CSIC (Proyecto intramural 200410E051)Peer reviewe

Crosstalk between phosphorylation and multi-site arginine/lysine methylation in C/EBPs

C/EBPs are implied in an amazing number of cellular functions: C/EBPs regulate tissue and cell type specific gene expression, proliferation and differentiation control. C/EBPs assist in energy metabolism, female reproduction, innate immunity, inflammation, senescence and the development of neoplasms. How can C/EBPs fulfill so many functions? Here we discuss that C/EBPs are extensively modified by methylation of arginine and lysine side chains and that regulated methylation profoundly affects the activity of C/EBPs

C/EBPβ PTM site mutations affect lympho-myeloid trans-differentiation.

<p>A. Schematic representation of C/EBPβ PTM sites and mutants tested in B-D. B. Expression of Ly-6C, M-CSFR and Ly-6G on the reprogrammed cells at 9 dpi. C. Distribution of the different myeloid populations among the reprogrammed GFP⁺ CD11b⁺ cells, stained as in B and presented as mean ± SEM. D. Cytospins of trans-differentiated sorted cells. Experiments were repeated two to three times and similar results were obtained. Gating strategies and abbreviations as in Fig. 3. E. Schematic representation of the normal hematopoiesis and lympho-myeloid reprogramming by C/EBPβ. MPP - multi potent progenitors, CLP - common lymphoid progenitor, CMP - common myeloid progenitor, GMP - granulocyte/macrophage progenitor, iMΦ and rMΦ - inflammatory and resident monocytes/macrophages.</p

C/EBPβ WT and mutants differentially regulate key myeloid genes.

<p>RNA counts for pro-inflammatory M1, anti-inflammatory M2 and other key monocyte/macrophage genes evaluated on CD11b⁺ reprogrammed <i>C/EBPβ</i>^−/− B cell progenitors. Data were calculated as log₂ and subjected to hierarchical clustering. Results represent expression profiles from three independent experiments. On the right, comparison to data obtained from reprogramming of pre-B cell line by C/EBPα is presented (Bussmann et al., 2009). MPh - WT bone marrow-derived macrophages.</p

Structural requirements for B cell to myeloid reprogramming potential of C/EBPβ.

<p>Schematic representation of the different C/EBPβ constructs (left) indicating the conserved regions (CRs) in the transactivation domain (TAD; CR1,2,3,4; green, turquoise), regulatory domain (RD; CR5,6,7; red), bZip domain (yellow), and the low complexity regions (LCRs, grey). Expression of lineage specific markers: B cell CD19 (red), myeloid CD11b (blue), or double positive (magenta) at 6 (middle panel) or 9 dpi (right panel). Bar graph shows percentage of GFP⁺ gated (virus infected) cell population; B cells - control uninfected GFP^– B cell progenitors. Results represent mean ± SEM from at least two experiments.</p