scholarly journals The Hybrid Histidine Kinase HrmK Is an Early-Acting Factor in the Hormogonium Gene Regulatory Network

2019 ◽  
Vol 202 (5) ◽  
Author(s):  
Esthefani G. Zuniga ◽  
Natalie M. Figueroa ◽  
Alfonso Gonzalez ◽  
Adriana P. Pantoja ◽  
Douglas D. Risser
Keyword(s):  
Gene Regulatory Network ◽  
Histidine Kinase ◽  
Sigma Factor ◽  
Regulatory Network ◽  
Gliding Motility ◽  
Model Organisms ◽  
Putative Hybrid ◽  
Nitrogen Fixing ◽  
Gene Regulatory ◽  
Hybrid Histidine Kinase

ABSTRACT Filamentous, heterocyst-forming cyanobacteria belonging to taxonomic subsections IV and V are developmentally complex multicellular organisms capable of differentiating an array of cell and filament types, including motile hormogonia. Hormogonia exhibit gliding motility that facilitates dispersal, phototaxis, and the establishment of nitrogen-fixing symbioses. The gene regulatory network (GRN) governing hormogonium development involves a hierarchical sigma factor cascade, but the factors governing the activation of this cascade are currently undefined. Here, using a forward genetic approach, we identified hrmK, a gene encoding a putative hybrid histidine kinase that functions upstream of the sigma factor cascade. The deletion of hrmK produced nonmotile filaments that failed to display hormogonium morphology or accumulate hormogonium-specific proteins or polysaccharide. Targeted transcriptional analyses using reverse transcription-quantitative PCR (RT-qPCR) demonstrated that hormogonium-specific genes both within and outside the sigma factor cascade are drastically downregulated in the absence of hrmK and that hrmK may be subject to indirect, positive autoregulation via sigJ and sigC. Orthologs of HrmK are ubiquitous among, and exclusive to, heterocyst-forming cyanobacteria. Collectively, these results indicate that hrmK functions upstream of the sigma factor cascade to initiate hormogonium development, likely by modulating the phosphorylation state of an unknown protein that may serve as the master regulator of hormogonium development in heterocyst-forming cyanobacteria. IMPORTANCE Filamentous cyanobacteria are morphologically complex, with several representative species amenable to routine genetic manipulation, making them excellent model organisms for the study of development. Furthermore, two of the developmental alternatives, nitrogen-fixing heterocysts and motile hormogonia, are essential to establish nitrogen-fixing symbioses with plant partners. These symbioses are integral to global nitrogen cycles and could be artificially recreated with crop plants to serve as biofertilizers, but to achieve this goal, detailed understanding and manipulation of the hormogonium and heterocyst gene regulatory networks may be necessary. Here, using the model organism Nostoc punctiforme, we identify a previously uncharacterized hybrid histidine kinase that is confined to heterocyst-forming cyanobacteria as the earliest known participant in hormogonium development.

Integrating genome-scale metabolic modelling and transfer learning for human gene regulatory network reconstruction

2021 ◽  
Author(s):  
Gianvito Pio ◽  
Paolo Mignone ◽  
Giuseppe Magazzù ◽  
Guido Zampieri ◽  
Michelangelo Ceci ◽  
...  
Keyword(s):  
Gene Expression ◽  
Gene Regulatory Network ◽  
Transfer Learning ◽  
Regulatory Network ◽  
Drug Targets ◽  
Human Gene ◽  
Supplementary Information ◽  
Model Organisms ◽  
Metabolic Modelling ◽  
Gene Regulatory

Abstract Motivation Gene regulation is responsible for controlling numerous physiological functions and dynamically responding to environmental fluctuations. Reconstructing the human network of gene regulatory interactions is thus paramount to understanding the cell functional organisation across cell types, as well as to elucidating pathogenic processes and identifying molecular drug targets. Although significant effort has been devoted towards this direction, existing computational methods mainly rely on gene expression levels, possibly ignoring the information conveyed by mechanistic biochemical knowledge. Moreover, except for a few recent attempts, most of the existing approaches only consider the information of the organism under analysis, without exploiting the information of related model organisms. Results We propose a novel method for the reconstruction of the human gene regulatory network, based on a transfer learning strategy that synergically exploits information from human and mouse, conveyed by gene-related metabolic features generated in-silico from gene expression data. Specifically, we learn a predictive model from metabolic activity inferred via tissue-specific metabolic modelling of artificial gene knockouts. Our experiments show that the combination of our transfer learning approach with the constructed metabolic features provides a significant advantage in terms of reconstruction accuracy, as well as additional clues on the contribution of each constructed metabolic feature. Availability The system, the datasets and all the results obtained in this study are available at: https://doi.org/10.6084/m9.figshare.c.5237687 Supplementary information Supplementary data are available at Bioinformatics online.

The primary transcriptome of hormogonia from a filamentous cyanobacterium defined by cappable-seq

Microbiology ◽  
2021 ◽  
Vol 167 (11) ◽  
Author(s):  
Thomas V. Harwood ◽  
Douglas D. Risser
Keyword(s):  
Gene Regulatory Network ◽  
Sigma Factor ◽  
Regulatory Network ◽  
Filamentous Cyanobacterium ◽  
Data Set ◽  
Protein Coding ◽  
Content Type ◽  
Biologically Relevant ◽  
Gene Regulatory ◽  
Transcriptional Start Sites

Hormogonia are motile filaments produced by many filamentous cyanobacteria that function in dispersal, phototaxis and the establishment of nitrogen-fixing symbioses. The gene regulatory network promoting hormogonium development is initiated by the hybrid histidine kinase HrmK, which in turn activates a sigma factor cascade consisting of SigJ, SigC and SigF. In this study, cappable-seq was employed to define the primary transcriptome of developing hormogonia in the model filamentous cyanobacterium Nostoc punctiforme ATCC 29133 in both the wild-type, and sigJ, sigC and sigF mutant strains 6 h post-hormogonium induction. A total of 1544 transcriptional start sites (TSSs) were identified that are associated with protein-coding genes and are expressed at levels likely to lead to biologically relevant transcripts in developing hormogonia. TSS expression among the sigma-factor deletion strains was highly consistent with previously reported gene expression levels from RNAseq experiments, and support the current working model for the role of these genes in hormogonium development. Analysis of SigJ-dependent TSSs corroborated the presence of the previously identified J-Box in the −10 region of SigJ-dependent promoters. Additionally, the data presented provides new insights on sequence conservation within the −10 regions of both SigC- and SigF-dependent promoters, and demonstrates that SigJ and SigC coordinate complex co-regulation not only of hormogonium-specific genes at different loci, but within an individual operon. As progress continues on defining the hormogonium gene regulatory network, this data set will serve as a valuable resource.

scholarly journals Study on the Relationship between the miRNA-centered ceRNA Regulatory Network and Fatigue

2021 ◽  
Author(s):  
Xingzhe Yang ◽  
Feng Li ◽  
Jie Ma ◽  
Yan Liu ◽  
Xuejiao Wang ◽  
...  
Keyword(s):  
Gene Expression ◽  
Gene Regulatory Network ◽  
Regulatory Network ◽  
Hot Spot ◽  
Genetic Research ◽  
Noncoding Rnas ◽  
Messenger Rnas ◽  
Effective Prevention ◽  
Gene Regulatory ◽  
The Relationship

AbstractIn recent years, the incidence of fatigue has been increasing, and the effective prevention and treatment of fatigue has become an urgent problem. As a result, the genetic research of fatigue has become a hot spot. Transcriptome-level regulation is the key link in the gene regulatory network. The transcriptome includes messenger RNAs (mRNAs) and noncoding RNAs (ncRNAs). MRNAs are common research targets in gene expression profiling. Noncoding RNAs, including miRNAs, lncRNAs, circRNAs and so on, have been developed rapidly. Studies have shown that miRNAs are closely related to the occurrence and development of fatigue. MiRNAs can regulate the immune inflammatory reaction in the central nervous system (CNS), regulate the transmission of nerve impulses and gene expression, regulate brain development and brain function, and participate in the occurrence and development of fatigue by regulating mitochondrial function and energy metabolism. LncRNAs can regulate dopaminergic neurons to participate in the occurrence and development of fatigue. This has certain value in the diagnosis of chronic fatigue syndrome (CFS). CircRNAs can participate in the occurrence and development of fatigue by regulating the NF-κB pathway, TNF-α and IL-1β. The ceRNA hypothesis posits that in addition to the function of miRNAs in unidirectional regulation, mRNAs, lncRNAs and circRNAs can regulate gene expression by competitive binding with miRNAs, forming a ceRNA regulatory network with miRNAs. Therefore, we suggest that the miRNA-centered ceRNA regulatory network is closely related to fatigue. At present, there are few studies on fatigue-related ncRNA genes, and most of these limited studies are on miRNAs in ncRNAs. However, there are a few studies on the relationship between lncRNAs, cirRNAs and fatigue. Less research is available on the pathogenesis of fatigue based on the ceRNA regulatory network. Therefore, exploring the complex mechanism of fatigue based on the ceRNA regulatory network is of great significance. In this review, we summarize the relationship between miRNAs, lncRNAs and circRNAs in ncRNAs and fatigue, and focus on exploring the regulatory role of the miRNA-centered ceRNA regulatory network in the occurrence and development of fatigue, in order to gain a comprehensive, in-depth and new understanding of the essence of the fatigue gene regulatory network.

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