The transcription factor LAG-1/CSL plays a Notch-independent role in controlling terminal differentiation, fate maintenance, and plasticity of serotonergic chemosensory neurons

During development, signal-regulated transcription factors (TFs) act as basal repressors and upon signalling through morphogens or cell-to-cell signalling shift to activators, mediating precise and transient responses. Conversely, at the final steps of neuron specification, terminal selector TFs directly initiate and maintain neuron-type specific gene expression through enduring functions as activators. C. elegans contains 3 types of serotonin synthesising neurons that share the expression of the serotonin biosynthesis pathway genes but not of other effector genes. Here, we find an unconventional role for LAG-1, the signal-regulated TF mediator of the Notch pathway, as terminal selector for the ADF serotonergic chemosensory neuron, but not for other serotonergic neuron types. Regulatory regions of ADF effector genes contain functional LAG-1 binding sites that mediate activation but not basal repression. lag-1 mutants show broad defects in ADF effector genes activation, and LAG-1 is required to maintain ADF cell fate and functions throughout life. Unexpectedly, contrary to reported basal repression state for LAG-1 prior to Notch receptor activation, gene expression activation in the ADF neuron by LAG-1 does not require Notch signalling, demonstrating a default activator state for LAG-1 independent of Notch. We hypothesise that the enduring activity of terminal selectors on target genes required uncoupling LAG-1 activating role from receiving the transient Notch signalling

Joint actions of diverse transcription factor families establish neuron-type identities and promote enhancer selectivity

16 páginas, 6 figuras, 2 tablasTo systematically investigate the complexity of neuron specification regulatory networks, we performed an RNA interference (RNAi) screen against all 875 transcription factors (TFs) encoded in Caenorhabditis elegans genome and searched for defects in nine different neuron types of the monoaminergic (MA) superclass and two cholinergic motoneurons. We identified 91 TF candidates to be required for correct generation of these neuron types, of which 28 were confirmed by mutant analysis. We found that correct reporter expression in each individual neuron type requires at least nine different TFs. Individual neuron types do not usually share TFs involved in their specification but share a common pattern of TFs belonging to the five most common TF families: homeodomain (HD), basic helix loop helix (bHLH), zinc finger (ZF), basic leucine zipper domain (bZIP), and nuclear hormone receptors (NHR). HD TF members are overrepresented, supporting a key role for this family in the establishment of neuronal identities. These five TF families are also prevalent when considering mutant alleles with previously reported neuronal phenotypes in C. elegans, Drosophila, and mouse. In addition, we studied terminal differentiation complexity focusing on the dopaminergic terminal regulatory program. We found two HD TFs (UNC-62 and VAB-3) that work together with known dopaminergic terminal selectors (AST-1, CEH-43, CEH-20). Combined TF binding sites for these five TFs constitute a cis-regulatory signature enriched in the regulatory regions of dopaminergic effector genes. Our results provide new insights on neuron-type regulatory programs in C. elegans that could help better understand neuron specification and evolution of neuron types.the Bioinformatics and Biostatistics Unit from Principe Felipe Research Center (CIPF) for providing access to the cluster, cofunded by European Regional Development Funds (FEDER); Funding sources: European Research Council: ERC-StG2011-281920; ERC-Co-2020-101002203; Ministerio de Economía, Industria y Competitividad, Gobierno de España: SAF2017-84790-R; PID2020-115635RB-I00; RED2018-102553-T; Conselleria de Innovación, Universidades, Ciencia y Sociedad Digital, Generalitat Valenciana: PROMETEO/2018/055; ACIF/2019/079.Peer reviewe

New insights on the transcriptional regulation of CD69 gene through a potent enhancer located in the conserved non-coding sequence 2

35 p.-8 fig.The CD69 type II C-type lectin is one ofthe earliestindicators of leukocyte activation acting in lymphocyte migration and cytokine secretion. CD69 expression in hematopoietic lineage undergoes rapid changes depending on the cell-lineage,the activation state or the localization ofthe cell where itis expressed, suggesting a complex and tightly controlled regulation. Here we provide new insights on the transcriptional regulation of CD69 gene in mammal species. Through in silico studies, we analyzed several regulatory features of the 4 upstream conserved non-coding sequences (CNS 1–4) previously described, confirming a major function of CNS2 in the transcriptional regulation of CD69. In addition, multiple transcription binding sites are identified in the CNS2 region by DNA cross-species conservation analysis. By functional approaches we defined a core region of 226 bp located within CNS2 as the main enhancer element of CD69 transcription in the hematopoietic cells analyzed. By chromatin immunoprecipitation, binding of RUNX1 to the core-CNS2 was shown in a T cell line. In addition, we found an activating but not essential role of RUNX1 in CD69 gene transcription by site-directed mutagenesis and RNA silencing, probably through the interaction with this potent enhancer specifically in the hematopoietic lineage. In summary, in this study we contribute with new evidences to the landscape of the transcriptional regulation of the CD69 gene.This work was supported by the Spanish Ministry of Economics (SAF2010-15649) and the Carlos III National Health Institute (ISCIII) – RTICC (RD12/0036/0063)Peer reviewe

New insights on the transcriptional regulation of CD69 gene through a potent enhancer located in the conserved non-coding sequence 2.

The CD69 type II C-type lectin is one of the earliest indicators of leukocyte activation acting in lymphocyte migration and cytokine secretion. CD69 expression in hematopoietic lineage undergoes rapid changes depending on the cell-lineage, the activation state or the localization of the cell where it is expressed, suggesting a complex and tightly controlled regulation. Here we provide new insights on the transcriptional regulation of CD69 gene in mammal species. Through in silico studies, we analyzed several regulatory features of the 4 upstream conserved non-coding sequences (CNS 1-4) previously described, confirming a major function of CNS2 in the transcriptional regulation of CD69. In addition, multiple transcription binding sites are identified in the CNS2 region by DNA cross-species conservation analysis. By functional approaches we defined a core region of 226bp located within CNS2 as the main enhancer element of CD69 transcription in the hematopoietic cells analyzed. By chromatin immunoprecipitation, binding of RUNX1 to the core-CNS2 was shown in a T cell line. In addition, we found an activating but not essential role of RUNX1 in CD69 gene transcription by site-directed mutagenesis and RNA silencing, probably through the interaction with this potent enhancer specifically in the hematopoietic lineage. In summary, in this study we contribute with new evidences to the landscape of the transcriptional regulation of the CD69 gene.We thank Dr. Elisenda Alari-Pahissa and Dr. Begoña Galocha for their critical review of the manuscript. This work was supported by the Spanish Ministry of Economics (SAF2010-15649) and the Carlos III National Health Institute (ISCIII)-RTICC (RD12/0036/0063). T. Laguna and L. Notario were supported by Predoctoral Fellowships from the Spanish Ministry of Education and Science.S

PBX1 acts as terminal selector for olfactory bulb dopaminergic neurons

15 páginas, 8 figuras. Supplementary information available online at http://dev.biologists.org/lookup/doi/10.1242/dev.186841.supplementalNeuronal specification is a protracted process that begins with the commitment of progenitor cells and culminates with the generation of mature neurons. Many transcription factors are continuously expressed during this process but it is presently unclear how these factors modify their targets as cells transition through different stages of specification. In olfactory bulb adult neurogenesis, the transcription factor PBX1 controls neurogenesis in progenitor cells and the survival of migrating neuroblasts. Here, we show that, at later differentiation stages, PBX1 also acts as a terminal selector for the dopaminergic neuron fate. PBX1 is also required for the morphological maturation of dopaminergic neurons and to repress alternative interneuron fates, findings that expand the known repertoire of terminal-selector actions. Finally, we reveal that the temporal diversification of PBX1 functions in neuronal specification is achieved, at least in part, through the dynamic regulation of alternative splicing. In Caenorhabditis elegans, PBX/CEH-20 also acts as a dopaminergic neuron terminal selector, which suggests an ancient role for PBX factors in the regulation of terminal differentiation of dopaminergic neurons.This work was supported by PhD fellowships from the Ministerio de Educación, Cultura y Deporte (FPU16/02008 to I.R.-B.) and the Ministerio de Economıa y ́Competitividad (BES-2012-053847 to L.R.. and BES-2015-072799 to R.B.-R.); by European Research Council grant (ERC-StG-2011-281920); by Ministerio de Economıa y Competitividad grants (SAF2017-84790-R and SAF2016-75004R) and ́ by the Generalitat Valenciana (PROMETEO/2018/055).Peer reviewe

The LIM and POU homeobox genes ttx-3 and unc-86 act as terminal selectors in distinct cholinergic and serotonergic neuron types.

14 páginas, 8 figuras, 1 tabla. Material suplementario accesible online.Transcription factors that drive neuron type-specific terminal differentiation programs in the developing nervous system are often expressed in several distinct neuronal cell types, but to what extent they have similar or distinct activities in individual neuronal cell types is generally not well explored. We investigate this problem using, as a starting point, the C. elegans LIM homeodomain transcription factor ttx-3, which acts as a terminal selector to drive the terminal differentiation program of the cholinergic AIY interneuron class. Using a panel of different terminal differentiation markers, including neurotransmitter synthesizing enzymes, neurotransmitter receptors and neuropeptides, we show that ttx-3 also controls the terminal differentiation program of two additional, distinct neuron types, namely the cholinergic AIA interneurons and the serotonergic NSM neurons. We show that the type of differentiation program that is controlled by ttx-3 in different neuron types is specified by a distinct set of collaborating transcription factors. One of the collaborating transcription factors is the POU homeobox gene unc-86, which collaborates with ttx-3 to determine the identity of the serotonergic NSM neurons. unc-86 in turn operates independently of ttx-3 in the anterior ganglion where it collaborates with the ARID-type transcription factor cfi-1 to determine the cholinergic identity of the IL2 sensory and URA motor neurons. In conclusion, transcription factors operate as terminal selectors in distinct combinations in different neuron types, defining neuron type-specific identity features.This work was funded by the National Institutes of Health [R01NS039996-05 and R01NS050266-03 to O.H.; R01NS076558 to D.A.C.-R.; and R01NS070644 to R.S.M.]; a March of Dimes Foundation Grant (to D.A.C.-R.); the Spanish Government [SAF2011-26273 to N.F.]; a Marie Curie Career Integration Grant (to N.F.); a VAL i+d Fellowship from Generalitat Valenciana (to C.L.-F.); and a European Research Council Starting Grant (to N.F.). N.F. is a National Alliance for Research on Schizophrenia and Depression (NARSAD) Young Investigator. O.H. is an Investigator of the Howard Hughes Medical Institute. Deposited in PMC for release after 6 months.Peer reviewe

Down-regulation of EVI1 is associated with epigenetic alterations and good prognosis in patients with acute myeloid leukemia

[Background]: The EVI1 gene (3q26) codes for a zinc finger transcription factor with important roles in both mammalian development and leukemogenesis. Over-expression of EVI1 through either 3q26 rearrangements, MLL fusions, or other unknown mechanisms confers a poor prognosis in acute myeloid leukemia. [Design and Methods]: We analyzed the prevalence and prognostic impact of EVI1 over-expression in a series of 476 patients with acute myeloid leukemia, and investigated the epigenetic modifications of the EVI1 locus which could be involved in the transcriptional regulation of this gene. [Results]: Our data provide further evidence that EVI1 over-expression is a poor prognostic marker in acute myeloid leukemia patients less than 65 years old. Moreover, we found that patients with no basal expression of EVI1 had a better prognosis than patients with expression/over-expression (P=0.036). We also showed that cell lines with over-expression of EVI1 had no DNA methylation in the promoter region of the EVI1 locus, and had marks of active histone modifications: H3 and H4 acetylation, and trimethylation of histone H3 lysine 4. Conversely, cell lines with no expression of EVI1 have DNA hypermethylation and are marked by repressive trimethylation of histone H3 lysine 27 at the EVI1 promoter. [Conclusions]: Our results identify EVI1 over-expression as a poor prognostic marker in a large, independent cohort of acute myeloid leukemia patients less than 65 years old, and show that the total absence of EVI1 expression has a prognostic impact on the outcome of such patients. Furthermore, we demonstrated for the first time that an aberrant epigenetic pattern involving DNA methylation, H3 and H4 acetylation, and trimethylation of histone H3 lysine 4 and histone H3 lysine 27 might play a role in the transcriptional regulation of EVI1 in acute myeloid leukemia. This study opens new avenues for a better understanding of the regulation of EVI1 expression at a transcriptional level.This work was supported by a grant of Ministerio Educación y Ciencia (SAF2005/06425), Ministerio Ciencia e Innovación (PI081687), AECC, Departamento Salud del Gobierno de Navarra (14/2008), Generalitat de Catalunya (2009-SGR-1246), Fundación Cellex, SACYL (355/4/09), ISCIII-RTICC (RD06/0020/0078, RD06/0020/0101, RD06/0020/0006, RD06/0020/0031), and Fundación para la Investigación Médica Aplicada y UTE (Spain).Peer Reviewe

Juntas / Juntes

Multitud d'autores i autors aporten píndoles de microliteratura, de gèneres diversos, al tercer volum amb què l'Institut Universitari d'Estudis Feministes i de Gènere Purificación Escribano vol respondre al desafiament per l'eradicació de la violència contra les dones.Tercer desafío por la erradicación de la violencia contra las mujeres del Institut Universitari d'Estudis Feministes i de Gènere Purificación Escribano de la Universitat Jaume I a través de microliteratura