analysis-transgenerational-epigenetic-inheritance-c-elegans-using

Analysis of Transgenerational Epigenetic Inheritance in <em>C. elegans</em> Using a Fluorescent Reporter and Chromatin Immunoprecipitation (ChIP)

Transgenerational epigenetic inheritance (TEI) allows the transmission of information through the germline without changing the genome sequence, through ...

University of Toronto

Tools for -mediated single copy insertion (mosSCI) with excisable  or NeoR (G418) selection cassettes.

In most eukaryotes, the genome is packaged with histones and other proteins to form chromatin. One of the major mechanisms for chromatin regulation is through post-translational modification of histone proteins. Recognition of these modifications by effector proteins, often dubbed histone "readers," provides a link between the chromatin landscape and gene regulation. The diversity of histone reader proteins for each modification provides an added layer of regulatory complexity. In this review, we will focus on the roles of chromatin organization modifier (chromo) domain containing proteins in the model nematode, . An amenability to genetic and cell biological approaches, well-studied development and a short life cycle make  a powerful system to investigate the diversity of chromo domain protein functions in metazoans. We will highlight recent insights into the roles of chromo domain proteins in the regulation of heterochromatin and the spatial conformation of the genome as well as their functions in cell fate, fertility, small RNA pathways and transgenerational epigenetic inheritance. The spectrum of different chromatin readers may represent a layer of regulation that integrates chromatin landscape, genome organization and gene expression.

Emerging Roles for Chromo Domain Proteins in Genome Organization and Cell Fate in .

RNA interference (RNAi) is a highly conserved gene regulatory phenomenon whereby Argonaute/small RNA (AGO/sRNA) complexes target transcripts by antisense complementarity to modulate gene expression. While initially appreciated as a cytoplasmic process, RNAi can also occur in the nucleus where AGO/sRNA complexes are recruited to nascent transcripts. Nuclear AGO/sRNA complexes recruit co-factors that regulate transcription by inhibiting RNA Polymerase II, modifying histones, compacting chromatin and, in some organisms, methylating DNA. C. elegans has a longstanding history in unveiling the mechanisms of RNAi and has become an outstanding model to delineate the mechanisms underlying nuclear RNAi. In this review we highlight recent discoveries in the field of nuclear RNAi in C. elegans and the roles of nuclear RNAi in the regulation of gene expression, chromatin organization, genome stability, and transgenerational epigenetic inheritance.

Mechanisms of epigenetic regulation by C. elegans nuclear RNA interference pathways.

Pathogens generate ubiquitous selective pressures and host-pathogen interactions alter social behaviours in many animals. However, very little is known about the neuronal mechanisms underlying pathogen-induced changes in social behaviour. Here we show that in adult Caenorhabditis elegans hermaphrodites, exposure to a bacterial pathogen (Pseudomonas aeruginosa) modulates sensory responses to pheromones by inducing the expression of the chemoreceptor STR-44 to promote mating. Under standard conditions, C. elegans hermaphrodites avoid a mixture of ascaroside pheromones to facilitate dispersal. We find that exposure to the pathogenic Pseudomonas bacteria enables pheromone responses in AWA sensory neurons, which mediate attractive chemotaxis, to suppress the avoidance. Pathogen exposure induces str-44 expression in AWA neurons, a process regulated by a transcription factor zip-5 that also displays a pathogen-induced increase in expression in AWA. STR-44 acts as a pheromone receptor and its function in AWA neurons is required for pathogen-induced AWA pheromone response and suppression of pheromone avoidance. Furthermore, we show that C. elegans hermaphrodites, which reproduce mainly through self-fertilization, increase the rate of mating with males after pathogen exposure and that this increase requires str-44 in AWA neurons. Thus, our results uncover a causal mechanism for pathogen-induced social behaviour plasticity, which can promote genetic diversity and facilitate adaptation of the host animals.

Article	Year
Tools for -mediated single copy insertion (mosSCI) with excisable or NeoR (G418) selection cassettes. microPublication biology\| PubMed ID: 32550440	2019
Emerging Roles for Chromo Domain Proteins in Genome Organization and Cell Fate in . Frontiers in cell and developmental biology\| PubMed ID: 33195254	2020
Mechanisms of epigenetic regulation by C. elegans nuclear RNA interference pathways. Seminars in cell & developmental biology\| PubMed ID: 34876343	2022
Pathogenic bacteria modulate pheromone response to promote mating. Nature\| PubMed ID: 36599989	2023

Chengyin Li

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