Transcriptional Autoregulation Research Articles

An anti-CRISPR that represses its own transcription while blocking Cas9-target DNA binding

AcrIIA15 is an anti-CRISPR (Acr) protein that inhibits Staphylococcus aureus Cas9 (SaCas9). Although previous studies suggested it has dual functions, the structural and biochemical basis for its two activities remains unclear. Here, we determined the cryo-EM structure of AcrIIA15 in complex with SaCas9-sgRNA to reveal the inhibitory mechanism of the Acr’s C-terminal domain (CTD) in mimicking dsDNA to block protospacer adjacent motif (PAM) recognition. For the N-terminal domain (NTD), our crystal structures of the AcrIIA15-promoter DNA show that AcrIIA15 dimerizes through its NTD to recognize double-stranded (ds) DNA. Further, AcrIIA15 can simultaneously bind to both SaCas9-sgRNA and promoter DNA, creating a supercomplex of two Cas9s bound to two CTDs converging on a dimer of the NTD bound to a dsDNA. These findings shed light on AcrIIA15’s inhibitory mechanisms and its autoregulation of transcription, enhancing our understanding of phage-host interactions and CRISPR defense.

Insights into the solution structure and transcriptional regulation of the MazE9 antitoxin in Mycobacterium tuberculosis.

The present study endeavors to decode the details of the transcriptional autoregulation effected by the MazE9 antitoxin of the Mycobacterium tuberculosis MazEF9 toxin-antitoxin system. Regulation of this bicistronic operon at the level of transcription is a critical biochemical process that is key for the organism's stress adaptation and virulence. Here, we have reported the solution structure of the DNA binding domain of MazE9 and scrutinized the thermodynamic and kinetic parameters operational in its interaction with the promoter/operator region, specific to the mazEF9 operon. A HADDOCK model of MazE9 bound to its operator DNA has been calculated based on the information on interacting residues obtained from these studies. The thermodynamics and kinetics of the interaction of MazE9 with the functionally related mazEF6 operon indicate that the potential for intracellular cross-regulation is unlikely. An interesting feature of MazE9 is the cis ⇌ trans conformational isomerization of proline residues in the intrinsically disordered C-terminal domain of this antitoxin.

Domains and residues of the Saccharomyces cerevisiae hnRNP protein Hrp1 important for transcriptional autoregulation and noncoding RNA termination.

Proteins that bind the nascent transcript exiting RNA polymerase II can regulate transcription elongation. The essential Saccharomyces cerevisiae hnRNP protein Hrp1 is one such protein and participates in both cleavage and polyadenylation-coupled and Nrd1-Nab3-Sen1-dependent RNA polymerase II termination. Prior evidence that Hrp1 is a positive RNA polymerase II elongation factor suggests that its release from the elongation complex promotes termination. Here we report the effects of deletions and substitutions in Hrp1 on its autoregulation via an Nrd1-Nab3-Sen1-dependent transcription attenuator in the 5'-UTR of its mRNA and on the function of an Hrp1-dependent Nrd1-Nab3-Sen1 terminator in the SNR82 snoRNA gene. Deletion of either of two central RNA recognition motifs or either of the flanking low-sequence complexity domains is lethal. Smaller, viable deletions in the amino-terminal low-sequence complexity domain cause readthrough of both the HRP1 attenuator and SNR82 terminator. Substitutions that cause readthrough localized mostly to the RNA recognition motifs, although not always to the RNA-binding face. We found that autoregulation of Hrp1 mRNA synthesis is surprisingly robust, overcoming the expected lethal effects of the start codon and frameshift mutations via overexpression of the mRNA up to 40-fold. Our results suggest a model in which binding of attenuator or terminator elements in the nascent transcript by RNA recognition motifs 1 and 2 disrupts interactions between RNA recognition motif 2 and the RNA polymerase II elongation complex, increasing its susceptibility to termination.

Autoregulation of Transcription and Translation: A Qualitative Analysis

The regulation of both mRNA transcription and translation by down-stream gene products allows for a range of rich dynamical behaviours (e.g. homeostatic, oscillatory, excitability and intermittent solutions). Here, qualitative analysis is applied to an existing model of a gene regulatory network in which a protein dimer inhibits its own transcription and upregulates its own translation rate. It is demonstrated that the model possesses a unique steady state, conditions are derived under which limit cycle solutions arise and estimates are provided for the oscillator period in the limiting case of a relaxation oscillator. The analysis demonstrates that oscillations can arise only if mRNA is more stable than protein and the effect of nonlinear translation inhibition is sufficiently strong. Moreover, it is shown that the oscillation period can vary non-monotonically with transcription rate. Thus the proposed framework can provide an explanation for observed species-specific dependency of segmentation clock period on Notch signalling activity. Finally, this study facilitates the application of the proposed model to more general biological settings where post transcriptional regulation effects are likely important.

Antibiotic-induced degradation of antitoxin enhances the transcription of acetyltransferase-type toxin-antitoxin operon.

Bacterial toxin-antitoxin (TA) modules respond to various stressful conditions. The Gcn5-related N-acetyltransferase-type toxin (GNAT) protein encoded by the GNAT-RHH TA locus is involved in the antibiotic tolerance of Klebsiella pneumoniae. To investigate the transcriptional mechanism of the GNAT-RHH operon kacAT under antibiotic stress. The transcriptional level of the kacAT operon of K. pneumoniae was measured by quantitative real-time (qRT) PCR assay. The degradation of antitoxin KacA was examined by western blot and fluorescent protein. The ratio of [KacA]:[KacT] was calculated by the fluorescence intensity of KacA-eGFP and mCherry-KacT. Mathematical modelling predicted protein and transcript synthesis dynamics. A meropenem-induced increase in transcript levels of kacA and kacT resulted from the relief from transcriptional autoregulation of the kacAT operon. Meropenem induces the degradation of KacA through Lon protease, resulting in a reduction in the ratio of [KacA]:[KacT]. The decreased ratio causes the dissociation of the KacAT complex from its promoter region, which eliminates the repression of kacAT transcription. In addition, our dynamic model of kacAT expression regulation quantitatively reproduced the experimentally observed reduction of the [KacA]:[KacT] ratio and a large increase in kacAT transcript levels under the condition of strong promoter autorepression by the KacAT complex. Meropenem promotes the degradation of antitoxin by enhancing the expression of Lon protease. Degradation of antitoxin reduces the ratio of intracellular [antitoxin]:[toxin], leading to detachment of the TA complex from its promoter, and releasing repression of TA operon transcription. These results may provide an important insight into the transcriptional mechanism of GNAT-RHH TA modules under antibiotic stress.

Maintenance of neurotransmitter identity by Hox proteins through a homeostatic mechanism

Hox transcription factors play fundamental roles during early patterning, but they are also expressed continuously, from embryonic stages through adulthood, in the nervous system. However, the functional significance of their sustained expression remains unclear. In C. elegans motor neurons (MNs), we find that LIN-39 (Scr/Dfd/Hox4-5) is continuously required during post-embryonic life to maintain neurotransmitter identity, a core element of neuronal function. LIN-39 acts directly to co-regulate genes that define cholinergic identity (e.g., unc-17/VAChT, cho-1/ChT). We further show that LIN-39, MAB-5 (Antp/Hox6-8) and the transcription factor UNC-3 (Collier/Ebf) operate in a positive feedforward loop to ensure continuous and robust expression of cholinergic identity genes. Finally, we identify a two-component design principle for homeostatic control of Hox gene expression in adult MNs: Hox transcriptional autoregulation is counterbalanced by negative UNC-3 feedback. These findings uncover a noncanonical role for Hox proteins during post-embryonic life, critically broadening their functional repertoire from early patterning to the control of neurotransmitter identity.

FAM64A promotes HNSCC tumorigenesis by mediating transcriptional autoregulation of FOXM1

Head and neck squamous cell carcinoma (HNSCC) still lacks effective targeted treatment. Therefore, exploring novel and robust molecular targets is critical for improving the clinical outcome of HNSCC. Here, we reported that the expression levels of family with sequence similarity 64, member A (FAM64A) were significantly higher in HNSCC tissues and cell lines. In addition, FAM64A overexpression was found to be strongly associated with an unfavorable prognosis of HNSCC. Both in vitro and in vivo evidence showed that FAM64A depletion suppressed the malignant activities of HNSCC cells, and vice versa. Moreover, we found that the FAM64A level was progressively increased from normal to dysplastic to cancerous tissues in a carcinogenic 4-nitroquinoline-1-oxide mouse model. Mechanistically, a physical interaction was found between FAM64A and forkhead box protein M1 (FOXM1) in HNSCC cells. FAM64A promoted HNSCC tumorigenesis not only by enhancing the transcriptional activity of FOXM1, but also, more importantly, by modulating FOXM1 expression via the autoregulation loop. Furthermore, a positive correlation between FAM64A and FOXM1 was found in multiple independent cohorts. Taken together, our findings reveal a previously unknown mechanism behind the activation of FOXM1 in HNSCC, and FAM64A might be a promising molecular therapeutic target for treating HNSCC.

AdpA Positively Regulates Morphological Differentiation and Chloramphenicol Biosynthesis in Streptomyces venezuelae.

ABSTRACTIn members of genus Streptomyces, AdpA is a master transcriptional regulator that controls the expression of hundreds of genes involved in morphological differentiation, secondary metabolite biosynthesis, chromosome replication, etc. However, the function of AdpASv, an AdpA ortholog of Streptomyces venezuelae, is unknown. This bacterial species is a natural producer of chloramphenicol and has recently become a model organism for studies on Streptomyces. Here, we demonstrate that AdpASv is essential for differentiation and antibiotic biosynthesis in S. venezuelae and provide evidence suggesting that AdpASv positively regulates its own gene expression. We speculate that the different modes of AdpA-dependent transcriptional autoregulation observed in S. venezuelae and other Streptomyces species reflect the arrangement of AdpA binding sites in relation to the transcription start site. Lastly, we present preliminary data suggesting that AdpA may undergo a proteolytic processing and we speculate that this may potentially constitute a novel regulatory mechanism controlling cellular abundance of AdpA in Streptomyces.IMPORTANCE Streptomyces are well-known producers of valuable secondary metabolites which include a large variety of antibiotics and important model organisms for developmental studies in multicellular bacteria. The conserved transcriptional regulator AdpA of Streptomyces exerts a pleiotropic effect on cellular processes, including the morphological differentiation and biosynthesis of secondary metabolites. Despite extensive studies, the function of AdpA in these processes remains elusive. This work provides insights into the role of a yet unstudied AdpA ortholog of Streptomyces venezuelae, now considered a novel model organism. We found that AdpA plays essential role in morphological differentiation and biosynthesis of chloramphenicol, a broad-spectrum antibiotic. We also propose that AdpA may undergo a proteolytic processing that presumably constitutes a novel mechanism regulating cellular abundance of this master regulator.

Insights into the Neutralization and DNA Binding of Toxin-Antitoxin System ParESO-CopASO by Structure-Function Studies.

ParESO-CopASO is a new type II toxin–antitoxin (TA) system in prophage CP4So that plays an essential role in circular CP4So maintenance after the excision in Shewanella oneidensis. The toxin ParESO severely inhibits cell growth, while CopASO functions as an antitoxin to neutralize ParESO toxicity through direct interactions. However, the molecular mechanism of the neutralization and autoregulation of the TA operon transcription remains elusive. In this study, we determined the crystal structure of a ParESO-CopASO complex that adopted an open V-shaped heterotetramer with the organization of ParESO-(CopASO)2-ParESO. The structure showed that upon ParESO binding, the intrinsically disordered C-terminal domain of CopASO was induced to fold into a partially ordered conformation that bound into a positively charged and hydrophobic groove of ParESO. Thermodynamics analysis showed the DNA-binding affinity of CopASO was remarkably higher than that of the purified TA complex, accompanied by the enthalpy change reversion from an exothermic reaction to an endothermic reaction. These results suggested ParESO acts as a de-repressor of the TA operon transcription at the toxin:antitoxin level of 1:1. Site-directed mutagenesis of ParESO identified His91 as the essential residue for its toxicity by cell toxicity assays. Our structure-function studies therefore elucidated the transcriptional regulation mechanism of the ParESO-CopASO pair, and may help to understand the regulation of CP4So maintenance in S. oneidensis.

The two paralogous copies of the YoeB–YefM toxin–antitoxin module in Staphylococcus aureus differ in DNA binding and recognition patterns

Toxin–antitoxin (TA) systems are ubiquitous regulatory modules for bacterial growth and cell survival following stress. YefM–YoeB, the most prevalent type II TA system, is present in a variety of bacterial species. In Staphylococcus aureus, the YefM–YoeB system exists as two independent paralogous copies. Our previous research resolved crystal structures of the two oligomeric states (heterotetramer and heterohexamer–DNA ternary complex) of the first paralog as well as the molecular mechanism of transcriptional autoregulation of this module. However, structural details reflecting molecular diversity in both paralogs have been relatively unexplored. To understand the molecular mechanism of how Sa2YoeB and Sa2YefM regulate their own transcription and how each paralog functions independently, we solved a series of crystal structures of the Sa2YoeB–Sa2YefM. Our structural and biochemical data demonstrated that both paralogous copies adopt similar mechanisms of transcriptional autoregulation. In addition, structural analysis suggested that molecular diversity between the two paralogs might be reflected in the interaction profile of YefM and YoeB and the recognition pattern of promoter DNA by YefM. Interaction analysis revealed unique conformational and activating force effected by the interface between Sa2YoeB and Sa2YefM. In addition, the recognition pattern analysis demonstrated that residues Thr7 and Tyr14 of Sa2YefM specifically recognizes the flanking sequences (G and C) of the promoter DNA. Together, these results provide the structural insights into the molecular diversity and independent function of the paralogous copies of the YoeB–YefM TA system.

Auto-Regulation of Transcription and Translation: Oscillations, Excitability and Intermittency.

Several members of the Hes/Her family, conserved targets of the Notch signalling pathway, encode transcriptional repressors that dimerise, bind DNA and self-repress. Such autoinhibition of transcription can yield homeostasis and, in the presence of delays that account for processes such as transcription, splicing and transport, oscillations. Whilst previous models of autoinhibition of transcription have tended to treat processes such as translation as being unregulated (and hence linear), here we develop and explore a mathematical model that considers autoinhibition of transcription together with nonlinear regulation of translation. It is demonstrated that such a model can yield, in the absence of delays, nonlinear dynamical behaviours such as excitability, homeostasis, oscillations and intermittency. These results indicate that regulation of translation as well as transcription allows for a much richer range of behaviours than is possible with autoregulation of transcription alone. A number of experiments are suggested that would that allow for the signature of autoregulation of translation as well as transcription to be experimentally detected in a Notch signalling system.

Chasing the structural diversity of the transcription regulator Mycobacterium tuberculosis HigA2.

Transcription factors are the primary regulators of gene expression and recognize specific DNA sequences under diverse physiological conditions. Although they are vital for many important cellular processes, it remains unclear when and how transcription factors and DNA interact. The antitoxin from a toxin-antitoxin system is an example of negative transcriptional autoregulation: during expression of the cognate toxin it is suppressed through binding to a specific DNA sequence. In the present study, the antitoxin HigA2 from Mycobacterium tuberculosis M37Rv was structurally examined. The crystal structure of M.tuberculosis HigA2 comprises three sections: an N-terminal autocleavage region, an α-helix bundle which contains an HTH motif, and a C-terminal β-lid. The N-terminal region is responsible for toxin binding, but was shown to cleave spontaneously in its absence. The HTH motif performs a key role in DNA binding, with the C-terminal β-lid influencing the interaction by mediating the distance between the motifs. However, M. tuberculosis HigA2 exhibits a unique coordination of the HTH motif and no DNA-binding activity is detected. Three crystal structures of M. tuberculosis HigA2 show a flexible alignment of the HTH motif, which implies that the motif undergoes structural rearrangement to interact with DNA. This study reveals the molecular mechanisms of how transcription factors interact with partner proteins or DNA.

FOXC2 Autoregulates Its Expression in the Pulmonary Endothelium After Endotoxin Stimulation in a Histone Acetylation-Dependent Manner.

The innate immune response of pulmonary endothelial cells (EC) to lipopolysaccharide (LPS) induces Forkhead box protein C2 (FOXC2) activation through Toll Like Receptor 4 (TLR4). The mechanisms by which FOXC2 expression is regulated in lung EC under LPS stimulation remain unclear. We postulated that FOXC2 regulates its own expression in sepsis, and its transcriptional autoregulation directs lymphatic EC cell-fate decision. Bioinformatic analysis identified potential FOXC2 binding sites in the FOXC2 promoter. In human lung EC, we verified using chromatin immunoprecipitation (ChIP) and luciferase assays that FOXC2 bound to its own promoter and stimulated its expression after LPS stimulation. Chemical inhibition of histone acetylation by garcinol repressed LPS-induced histone acetylation in the FOXC2 promoter region, and disrupted LPS-mediated FOXC2 binding and transcriptional activation. CRISPR/dCas9/gRNA directed against FOXC2-binding-element (FBE) suppressed LPS-stimulated FOXC2 binding and autoregulation by blocking FBEs in the FOXC2 promoter, and repressed expression of lymphatic EC markers. In a neonatal mouse model of sterile sepsis, LPS-induced FOXC2 binding to FBE and FOXC2 expression in lung EC was attenuated with garcinol treatment. These data reveal a new mechanism of LPS-induced histone acetylation-dependent FOXC2 autoregulation.

Dynamical gene regulatory networks are tuned by transcriptional autoregulation with microRNA feedback

Concepts from dynamical systems theory, including multi-stability, oscillations, robustness and stochasticity, are critical for understanding gene regulation during cell fate decisions, inflammation and stem cell heterogeneity. However, the prevalence of the structures within gene networks that drive these dynamical behaviours, such as autoregulation or feedback by microRNAs, is unknown. We integrate transcription factor binding site (TFBS) and microRNA target data to generate a gene interaction network across 28 human tissues. This network was analysed for motifs capable of driving dynamical gene expression, including oscillations. Identified autoregulatory motifs involve 56% of transcription factors (TFs) studied. TFs that autoregulate have more interactions with microRNAs than non-autoregulatory genes and 89% of autoregulatory TFs were found in dual feedback motifs with a microRNA. Both autoregulatory and dual feedback motifs were enriched in the network. TFs that autoregulate were highly conserved between tissues. Dual feedback motifs with microRNAs were also conserved between tissues, but less so, and TFs regulate different combinations of microRNAs in a tissue-dependent manner. The study of these motifs highlights ever more genes that have complex regulatory dynamics. These data provide a resource for the identification of TFs which regulate the dynamical properties of human gene expression.

Stress Can Induce Transcription of Toxin-Antitoxin Systems without Activating Toxin

Toxin-antitoxin (TA) systems are ubiquitous genetic elements in bacterial genomes, but their functions are controversial. Although they are frequently postulated to regulate cell growth following stress, few null phenotypes for TA systems have been reported. Here, we show that TA transcript levels can increase substantially in response to stress, but toxin is not liberated. We find that the growth of an Escherichia coli strain lacking ten TA systems encoding endoribonuclease toxins is not affected following exposure to six stresses that each trigger TA transcription. Additionally, using RNA sequencing, we find no evidence of mRNA cleavage following stress. Stress-induced transcription arises from antitoxin degradation and relief of transcriptional autoregulation. Importantly, although free antitoxin is readily degraded invivo, antitoxin bound to toxin is protected from proteolysis, preventing release of active toxin. Thus, transcription is not a reliable marker of TA activity, and TA systems do not strongly promote survival following individual stresses.

CREB Family Transcription Factors Are Major Mediators of BDNF Transcriptional Autoregulation in Cortical Neurons.

BDNF signaling via its transmembrane receptor TrkB has an important role in neuronal survival, differentiation, and synaptic plasticity. Remarkably, BDNF is capable of modulating its own expression levels in neurons, forming a transcriptional positive feedback loop. In the current study, we have investigated this phenomenon in primary cultures of rat cortical neurons using overexpression of dominant-negative forms of several transcription factors, including CREB, ATF2, C/EBP, USF, and NFAT. We show that CREB family transcription factors, together with the coactivator CBP/p300, but not the CRTC family, are the main regulators of rat BDNF gene expression after TrkB signaling. CREB family transcription factors are required for the early induction of all the major BDNF transcripts, whereas CREB itself directly binds only to BDNF promoter IV, is phosphorylated in response to BDNF-TrkB signaling, and activates transcription from BDNF promoter IV by recruiting CBP. Our complementary reporter assays with BDNF promoter constructs indicate that the regulation of BDNF by CREB family after BDNF-TrkB signaling is generally conserved between rat and human. However, we demonstrate that a nonconserved functional cAMP-responsive element in BDNF promoter IXa in humans renders the human promoter responsive to BDNF-TrkB-CREB signaling, whereas the rat ortholog is unresponsive. Finally, we show that extensive BDNF transcriptional autoregulation, encompassing all major BDNF transcripts, occurs also in vivo in the adult rat hippocampus during BDNF-induced LTP. Collectively, these results improve the understanding of the intricate mechanism of BDNF transcriptional autoregulation.SIGNIFICANCE STATEMENT Deeper understanding of stimulus-specific regulation of BDNF gene expression is essential to precisely adjust BDNF levels that are dysregulated in various neurological disorders. Here, we have elucidated the molecular mechanisms behind TrkB signaling-dependent BDNF mRNA induction and show that CREB family transcription factors are the main regulators of BDNF gene expression after TrkB signaling. Our results suggest that BDNF-TrkB signaling may induce BDNF gene expression in a distinct manner compared with neuronal activity. Moreover, our data suggest the existence of a stimulus-specific distal enhancer modulating BDNF gene expression.

Toxin-antitoxin operon kacAT of Klebsiella pneumoniae is regulated by conditional cooperativity via a W-shaped KacA-KacT complex.

Bacterial toxin–antitoxin pairs play important roles in bacterial multidrug tolerance. Gcn5-related N-acetyltransferase (GNAT) toxins inhibit translation by acetylation of aminoacyl-tRNAs and are counteracted by direct contacts with cognate ribbon–helix–helix (RHH) antitoxins. Our previous analysis showed that the GNAT toxin KacT and RHH antitoxin KacA of Klebsiella pneumoniae form a heterohexamer in solution and that the complex interacts with the cognate promoter DNA, resulting in negative autoregulation of kacAT transcription. Here, we present the crystal structure of DNA-bound KacAT complex at 2.2 Å resolution. The crystal structure revealed the formation of a unique heterohexamer, KacT–KacA2–KacA2–KacT. The direct interaction of KacA and KacT involves a unique W-shaped structure with the two KacT molecules at opposite ends. Inhibition of KacT is achieved by the binding of four KacA proteins that preclude the formation of an active KacT dimer. The kacAT operon is auto-regulated and we present an experimentally supported molecular model proposing that the KacT:KacA ratio controls kacAT transcription by conditional cooperativity. These results yield a profound understanding of how transcription GNAT–RHH pairs are regulated.

Post-Transcriptional Noise Control.

Recent evidence indicates that transcriptional bursts are intrinsically amplified by messenger RNA cytoplasmic processing to generate large stochastic fluctuations in protein levels. These fluctuations can be exploited by cells to enable probabilistic bet-hedging decisions. But large fluctuations in geneexpression can also destabilize cell-fate commitment. Thus, it is unclear if cells temporally switch from high to low noise, and what mechanisms enable this switch. Here, the discovery of a post-transcriptional mechanism that attenuates noise in HIV is reviewed. Early in its life cycle, HIV amplifies transcriptional fluctuations to probabilistically select alternate fates, whereas at late times, HIV utilizes a post-transcriptional feedback mechanism to commit to a specific fate. Reanalyzing various reported post-transcriptional negative feedback architectures reveals that they attenuate noise more efficiently than classic transcriptional autorepression, leading to the derivation of an assay to detect post-transcriptional motifs. It is hypothesized that coupling transcriptional and post-transcriptional autoregulation enables efficient temporal noise control to benefit developmental bet-hedging decisions.

Transcription factor autoregulation is required for acquisition and maintenance of neuronal identity.

The expression of transcription factors that initiate the specification of a unique cellular identity in multicellular organisms is often maintained throughout the life of the respective cell type via an autoregulatory mechanism. It is generally assumed that such autoregulation serves to maintain the differentiated state of a cell. To experimentally test this assumption, we used CRISPR/Cas9-mediated genome engineering to delete a transcriptional autoregulatory, cis-acting motif in the che-1 zinc-finger transcription factor locus, a terminal selector required to specify the identity of the ASE neuron pair during embryonic development of the nematode Caenorhabditis elegans. We show that che-1 autoregulation is indeed required to maintain the differentiated state of the ASE neurons but that it is also required to amplify che-1 expression during embryonic development to reach an apparent minimal threshold to initiate the ASE differentiation program. We conclude that transcriptional autoregulation fulfills two intrinsically linked purposes: one in proper initiation, the other in proper maintenance of terminal differentiation programs.This article has an associated 'The people behind the papers' interview.

The people behind the papers - Eduardo Leyva-Díaz and Oliver Hobert.

Transcriptional autoregulation occurs when transcription factors bind their own cis-regulatory sequences, ensuring their own continuous expression along with expression of other targets. During development, continued expression of identity-specifying transcription factors can be achieved by autoregulation, but until now formal evidence for a developmental requirement of autoregulation has been lacking. A new paper in Development provides this proof with the help of CRISPR/Cas9 gene editing in the C. elegans nervous system. We caught up with the paper's two authors: postdoc Eduardo Leyva-Díaz and his supervisor Oliver Hobert, Professor of Biological Sciences and HHMI Investigator at Columbia University, New York, to find out more about the work.