scholarly journals Transcription factors from multiple families ensure enhancer selectivity and robust neuron terminal differentiation

2020 ◽  
Author(s):  
Angela Jimeno-Martín ◽  
Erick Sousa ◽  
Noemi Daroqui ◽  
Rebeca Brocal-Ruiz ◽  
Miren Maicas ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Rna Interference ◽  
Terminal Differentiation ◽  
Specific Gene ◽  
Neuron Type ◽  
C Elegans ◽  
Effector Genes ◽  
Genetic Robustness ◽  
Gene Regulatory ◽  
Dopaminergic Terminal

SUMMARYTo search for general principles underlying neuronal regulatory programs we built an RNA interference library against all transcription factors (TFs) encoded in C. elegans genome and systematically screened for specification defects in ten different neuron types of the monoaminergic (MA) superclass.We identified over 90 TFs involved in MA specification, with at least ten different TFs controlling differentiation of each individual neuron type. These TFs belong predominantly to five TF families (HD, bHLH, ZF, bZIP and NHR). Next, focusing on the complexity of terminal differentiation, we identified and functionally characterized the dopaminergic terminal regulatory program. We found that seven TFs from four different families act in a TF collective to provide genetic robustness and to impose a specific gene regulatory signature enriched in the regulatory regions of dopamine effector genes. Our results provide new insights on neuron-type regulatory programs that could help better understand specification and evolution of neuron types.

scholarly journals In silico analysis of the transcriptional regulatory logic of neuronal identity specification throughout the C. elegans nervous system

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Lori Glenwinkel ◽  
Seth R Taylor ◽  
Kasper Langebeck-Jensen ◽  
Laura Pereira ◽  
Molly B Reilly ◽  
...  
Keyword(s):  
Nervous System ◽  
Transcription Factors ◽  
Single Cell ◽  
Expression Profiles ◽  
Neuronal Cell ◽  
In Silico Analysis ◽  
Specific Gene ◽  
Neuron Type ◽  
C Elegans ◽  
Neuronal Identity

The generation of the enormous diversity of neuronal cell types in a differentiating nervous system entails the activation of neuron type-specific gene batteries. To examine the regulatory logic that controls the expression of neuron type-specific gene batteries, we interrogate single cell expression profiles of all 118 neuron classes of the Caenorhabditis elegans nervous system for the presence of DNA binding motifs of 136 neuronally expressed C. elegans transcription factors. Using a phylogenetic footprinting pipeline, we identify cis-regulatory motif enrichments among neuron class-specific gene batteries and we identify cognate transcription factors for 117 of the 118 neuron classes. In addition to predicting novel regulators of neuronal identities, our nervous system-wide analysis at single cell resolution supports the hypothesis that many transcription factors directly co-regulate the cohort of effector genes that define a neuron type, thereby corroborating the concept of so-called terminal selectors of neuronal identity. Our analysis provides a blueprint for how individual components of an entire nervous system are genetically specified.

scholarly journals Multiple neural bHLHs ensure the precision of a neuronal specification event in C. elegans

Biology Open ◽  
2021 ◽  
Author(s):  
Konstantina Filippopoulou ◽  
Carole Couillault ◽  
Vincent Bertrand
Keyword(s):  
Transcription Factors ◽  
Quantitative Imaging ◽  
Terminal Differentiation ◽  
Cholinergic Neurons ◽  
Antagonistic Effect ◽  
Specific Class ◽  
C Elegans ◽  
Neuronal Specification ◽  
Bhlh Transcription Factors ◽  
Deleterious Genes

Neural bHLH transcription factors play a key role in the early steps of neuronal specification in many animals. We have previously observed that the Achaete-Scute HLH-3, the Olig HLH-16 and their binding partner the E protein HLH-2 activate the terminal differentiation program of a specific class of cholinergic neurons, AIY, in C. elegans. Here we identify a role for a fourth bHLH, the Neurogenin NGN-1, in this process, raising the question of why so many neural bHLHs are required for a single neuronal specification event. Using quantitative imaging we show that the combined action of different bHLHs is needed to activate the correct level of expression of the terminal selector transcription factors TTX-3 and CEH-10 that subsequently initiate and maintain the expression of a large battery of terminal differentiation genes. Surprisingly, the different bHLHs have an antagonistic effect on another target, the proapoptotic BH3-only factor EGL-1, normally not expressed in AIY and otherwise detrimental for its specification. We propose that the use of multiple neural bHLHs allows robust neuronal specification while, at the same time, preventing spurious activation of deleterious genes.

scholarly journals Transcription Factors That Control Behavior—Lessons From C. elegans

2021 ◽  
Vol 15 ◽  
Author(s):  
Rasoul Godini ◽  
Ava Handley ◽  
Roger Pocock
Keyword(s):  
Transcription Factors ◽  
Expression Patterns ◽  
Behavioral Responses ◽  
Gene Expression Patterns ◽  
Specific Gene ◽  
C Elegans ◽  
Control Behavior ◽  
A Cell ◽  
Physical And Chemical ◽  
Chemical Response

Behavior encompasses the physical and chemical response to external and internal stimuli. Neurons, each with their own specific molecular identities, act in concert to perceive and relay these stimuli to drive behavior. Generating behavioral responses requires neurons that have the correct morphological, synaptic, and molecular identities. Transcription factors drive the specific gene expression patterns that define these identities, controlling almost every phenomenon in a cell from development to homeostasis. Therefore, transcription factors play an important role in generating and regulating behavior. Here, we describe the transcription factors, the pathways they regulate, and the neurons that drive chemosensation, mechanosensation, thermosensation, osmolarity sensing, complex, and sex-specific behaviors in the animal model Caenorhabditis elegans. We also discuss the current limitations in our knowledge, particularly our minimal understanding of how transcription factors contribute to the adaptive behavioral responses that are necessary for organismal survival.

scholarly journals A developmental gene regulatory network for invasive differentiation of theC. elegansanchor cell

2019 ◽  
Author(s):  
Taylor N. Medwig-Kinney ◽  
Jayson J. Smith ◽  
Nicholas J. Palmisano ◽  
Sujata Tank ◽  
Wan Zhang ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Gene Regulatory Network ◽  
Cell Fate ◽  
Regulatory Network ◽  
Cell Biology ◽  
Type I ◽  
Cell Specification ◽  
C Elegans ◽  
Gene Regulatory ◽  
Anchor Cell

ABSTRACTCellular invasion is a key part of development, immunity, and disease. Using thein vivomodel ofC. elegansanchor cell invasion, we characterize the gene regulatory network that promotes invasive differentiation. The anchor cell is initially specified in a stochastic cell fate decision mediated by Notch signaling. Previous research has identified four conserved transcription factors,fos-1a(Fos),egl-43(EVI1/MEL),hlh-2(E/Daughterless) andnhr-67(NR2E1/TLX), that mediate anchor cell specification and/or invasive differentiation. Connections between these transcription factors and the underlying cell biology that they regulate is poorly understood. Here, using genome editing and RNA interference, we examine transcription factor interactions prior to and after anchor cell specification. During invasion we identify thategl-43,hlh-2, andnhr-67function together in a type I coherent feed-forward loop with positive feedback. Conversely, prior to specification, these transcription factors function independent of one another to regulate LIN-12 (Notch) activity. Together, these results demonstrate that, although the same transcription factors can function in fate specification and differentiated cell behavior, a gene regulatory network can be rapidly re-wired to reinforce a post-mitotic, pro-invasive state.SUMMARY STATEMENTBasement membrane invasion by theC. elegansanchor cell is coordinated by a dynamic gene regulatory network encompassing cell cycle dependent and independent sub-circuits.

scholarly journals An intersectional gene regulatory strategy defines subclass diversity of C. elegans motor neurons

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Paschalis Kratsios ◽  
Sze Yen Kerk ◽  
Catarina Catela ◽  
Joseph Liang ◽  
Berta Vidal ◽  
...  
Keyword(s):  
Motor Neurons ◽  
Hox Proteins ◽  
C Elegans ◽  
Molecular Features ◽  
Large Sets ◽  
Effector Genes ◽  
Regulatory Strategy ◽  
Specific Effector ◽  
Gene Regulatory ◽  
Anterior Posterior

A core principle of nervous system organization is the diversification of neuron classes into subclasses that share large sets of features but differ in select traits. We describe here a molecular mechanism necessary for motor neurons to acquire subclass-specific traits in the nematode Caenorhabditis elegans. Cholinergic motor neuron classes of the ventral nerve cord can be subdivided into subclasses along the anterior-posterior (A-P) axis based on synaptic connectivity patterns and molecular features. The conserved COE-type terminal selector UNC-3 not only controls the expression of traits shared by all members of a neuron class, but is also required for subclass-specific traits expressed along the A-P axis. UNC-3, which is not regionally restricted, requires region-specific cofactors in the form of Hox proteins to co-activate subclass-specific effector genes in post-mitotic motor neurons. This intersectional gene regulatory principle for neuronal subclass diversification may be conserved from nematodes to mice.

scholarly journals Automated generation of context-specific Gene Regulatory Networks with a weighted approach in D. melanogaster

2020 ◽  
Author(s):  
Leandro Murgas ◽  
Sebastian Contreras-Riquelme ◽  
J. Eduardo Martínez ◽  
Camilo Villaman ◽  
Rodrigo Santibáñez ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcription Factors ◽  
Gene Regulatory Networks ◽  
Regulatory Networks ◽  
Current Knowledge ◽  
Regulation Of Gene Expression ◽  
Chromatin Accessibility ◽  
Reference Network ◽  
Specific Gene ◽  
Gene Regulatory

AbstractMotivationThe regulation of gene expression is a key factor in the development and maintenance of life in all organisms. This process is carried out mainly through the action of transcription factors (TFs), although other actors such as ncRNAs are involved. In this work, we propose a new method to construct Gene Regulatory Networks (GRNs) depicting regulatory events in a certain context for Drosophila melanogaster. Our approach is based on known relationships between epigenetics and the activity of transcription factors.ResultsWe developed method, Tool for Weighted Epigenomic Networks in D. melanogaster (Fly T-WEoN), which generates GRNs starting from a reference network that contains all known gene regulations in the fly. Regulations that are unlikely taking place are removed by applying a series of knowledge-based filters. Each of these filters is implemented as an independent module that considers a type of experimental evidence, including DNA methylation, chromatin accessibility, histone modifications, and gene expression. Fly T-WEoN is based on heuristic rules that reflect current knowledge on gene regulation in D. melanogaster obtained from literature. Experimental data files can be generated with several standard procedures and used solely when and if available.Fly T-WEoN is available as a Cytoscape application that permits integration with other tools, and facilitates downstream network analysis. In this work, we first demonstrate the reliability of our method to then provide a relevant application case of our tool: early development of D. melanogaster.AvailabilityFly T-WEoN, together with its step-by-step guide is available at https://[email protected]

scholarly journals The enteric nervous system of C. elegans is specified by the Sine Oculis-like homeobox gene ceh-34

2021 ◽  
Author(s):  
Berta Vidal ◽  
Burcu Gulez ◽  
Wen Xi Cao ◽  
Eduardo Leyva Diaz ◽  
Tessa Tekieli ◽  
...  
Keyword(s):  
Nervous System ◽  
Enteric Nervous System ◽  
Critical Role ◽  
Terminal Differentiation ◽  
Homeobox Gene ◽  
Neuron Type ◽  
Nervous Systems ◽  
Sine Oculis ◽  
C Elegans ◽  
Circuit Assembly

Overarching themes in the terminal differentiation of the enteric nervous system, an autonomously acting unit of animal nervous systems, have so far eluded discovery. We describe here the overall regulatory logic of enteric nervous system differentiation of the nematode C. elegans that resides within the foregut (pharynx) of the worm. A Caenorhabditis elegans homolog of the Drosophila Sine Oculis homeobox gene, ceh-34, is expressed in all 14 classes of interconnected pharyngeal neurons from their birth throughout their life time, but in no other neuron type of the entire animal. Constitutive and temporally controlled ceh-34 removal shows that ceh-34 is required to initiate and maintain the neuron type-specific terminal differentiation program of all pharyngeal neuron classes, including their circuit assembly, without affecting panneuronal features. Through additional genetic loss of function analysis, we show that within each pharyngeal neuron class, ceh-34 cooperates with different homeodomain transcription factors to individuate distinct pharyngeal neuron classes. Our analysis underscores the critical role of homeobox genes in neuronal identity specification and links them to the control of neuronal circuit assembly of the enteric nervous system. Together with the pharyngeal nervous system simplicity as well as its specification by a Sine Oculis homolog, our findings invite speculations about the early evolution of nervous systems.

scholarly journals Timing mechanism of sexually dimorphic nervous system differentiation

2018 ◽  
Author(s):  
Laura Pereira ◽  
Florian Aeschimann ◽  
Chen Wang ◽  
Hannah Lawson ◽  
Esther Serrano-Saiz ◽  
...  
Keyword(s):  
Nervous System ◽  
Transcription Factors ◽  
Sexual Maturation ◽  
Sexual Differentiation ◽  
Rna Binding ◽  
Receptor Expression ◽  
Sexually Dimorphic ◽  
Neuron Type ◽  
C Elegans ◽  
Male Specific

ABSTRACTIn all animals, sexual differentiation of somatic tissue is precisely timed, yet the molecular mechanisms that control the timing of sexual differentiation, particularly in the brain, are poorly understood. We have used sexually dimorphic molecular, anatomical and behavioral features of the C. elegans nervous system to decipher a regulatory pathway that controls the precise timing of sexual differentiation. We find that the sexually dimorphic differentiation of postmitotic neurons in the male nervous system is abrogated in animals that carry a mutation in the miRNA let-7 and prematurely executed in animals either lacking the let-7 inhibitor lin-28, or the direct let-7 target lin-41, an RNA-binding, posttranscriptional regulator. We show that an isoform of a phylogenetically conserved transcription factor, lin-29a, is a critical target of LIN-41 in controlling sexual maturation of sex-shared neurons. lin-29a is expressed in a male-specific manner in a subset of sex-shared neurons at the onset of sexual maturation. lin-29a acts cell-autonomously in these neurons to control the expression of sexually dimorphic neurotransmitter switches, sensory receptor expression, neurite anatomy and connectivity, and locomotor behavior. lin-29a is not only required but also sufficient to impose male-specific features at earlier stages of development and in the opposite sex. The temporal, sexual and spatial specificity of lin-29a expression is controlled intersectionally through the lin-28/let-7/lin-41 heterochronic pathway, sex chromosome configuration and neuron type-specific terminal selector transcription factors. Two Doublesex-like transcription factors represent additional neuron-type specific targets of LIN-41 and are regulated in a similar intersectional manner, indicating the existence of modular outputs downstream of the heterochronic pathway. In conclusion, we have provided insights into the molecular logic of the timing of sexual differentiation in the C. elegans nervous system. Remarkably, the lin28/let7 axis also controls the timing of sexual differentiation in mice and humans thereby hinting toward a striking universality of the control mechanisms of sexual differentiation.

UNCOVER CONTEXT-SPECIFIC GENE REGULATION BY TRANSCRIPTION FACTORS AND microRNAs USING BAYESIAN SPARSE NONNEGATIVE FACTOR REGRESSION

2012 ◽  
Vol 20 (04) ◽  
pp. 377-402
Author(s):  
JIA MENG ◽  
YIDONG CHEN ◽  
YUFEI HUANG
Keyword(s):  
Transcription Factors ◽  
Gene Regulatory Network ◽  
Gibbs Sampling ◽  
Regulatory Network ◽  
Messenger Rna ◽  
The Cancer Genome Atlas ◽  
Specific Gene ◽  
Data Types ◽  
Gene Regulatory ◽  
Factor Regression

In multicellular organisms, transcription factors (TFs) and microRNAs (miRNA) embody two largest families of molecules that modulate messenger RNA (mRNA) expressions through transcriptional and post-transcriptional regulations. While mRNA and microRNA expressions can be measured by microarray technique, the activities of transcription factors manifested by their protein expression are still difficult to observe, making it usually a complex problem to reconstruct a collaborative gene regulatory network (GRN) by TFs and miRNAs from expression data. In this paper, a novel Bayesian sparse non-negative factor regression (BSNFR) model is proposed for modeling the joint regulations of mRNAs by TFs and miRNAs and integration of multiple data types including gene expressions, microRNA expressions, TF targeted genes, and microRNA targets. Powered by a Gibbs sampling solution, BSNFR can infer both the TF/microRNA-mediated mRNA regulations and the unknown TF activities. Additionally, since BSNFR directly models the non-negative activities of TFs, it avoids the common problem of sign ambiguity with factor models and is capable of accurate prediction of the types (up or down) of regulations as well. BSNFR also includes a nonparametric Bayesian model for the latent factor activities, which enables the discovery of the clustering effects among samples due to (disease) subtypes. The proposed BSNFR model and the developed Gibbs sampling solution were validated on simulated systems and applied to real data of glioblastoma multiforme (GBM) patients from The Cancer Genome Atlas (TCGA). A GBM specific gene regulatory network by TFs and miRNAs was reconstructed. This GBM network includes 107 regulations recorded in the existing databases and 16 new regulations. Functional analysis suggests that the regulated genes are enriched in cell cycle and P53 pathways. In addition, BSNFR also identified 3 clusters among GBM patient samples, two of which demonstrates significant survival differences (p=0.004). Finally, the estimated TF activities imply that EGR-1 is significantly correlated with patient survivals (p=0.004) and may be used as a prognostic biomarker. The data and matlab code are available at: http://compgenomics.cbi.utsa.edu/BSNFR .

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