skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: Multiple pals gene modules control a balance between immunity and development in Caenorhabditis elegans
The immune system continually battles against pathogen-induced pressures, which often leads to the evolutionary expansion of immune gene families in a species-specific manner. For example, thepalsgene family expanded to 39 members in theCaenorhabditis elegansgenome, in comparison to a single mammalianpalsortholog. Our previous studies have revealed that two members of this family,pals-22andpals-25, act as antagonistic paralogs to control the Intracellular Pathogen Response (IPR). The IPR is a protective transcriptional response, which is activated upon infection by two molecularly distinct natural intracellular pathogens ofC.elegans–the Orsay virus and the fungusNematocida parisiifrom the microsporidia phylum. In this study, we identify a previously uncharacterized member of thepalsfamily,pals-17, as a newly described negative regulator of the IPR.pals-17mutants show constitutive upregulation of IPR gene expression, increased immunity against intracellular pathogens, as well as impaired development and reproduction. We also find that two other previously uncharacterizedpalsgenes,pals-20andpals-16, are positive regulators of the IPR, acting downstream ofpals-17. These positive regulators reverse the effects caused by the loss ofpals-17on IPR gene expression, immunity, and development. We show that the negative IPR regulator protein PALS-17 and the positive IPR regulator protein PALS-20 colocalize inside and at the apical side of intestinal epithelial cells, which are the sites of infection for IPR-inducing pathogens. In summary, our study demonstrates that severalpalsgenes from the expandedpalsgene family act as ON/OFF switch modules to regulate a balance between organismal development and immunity against natural intracellular pathogens inC.elegans.  more » « less
Award ID(s):
2301657
PAR ID:
10477684
Author(s) / Creator(s):
; ; ;
Editor(s):
Schneider, David S.
Publisher / Repository:
NSF Public Access Repository
Date Published:
Journal Name:
PLOS Pathogens
Volume:
19
Issue:
7
ISSN:
1553-7374
Page Range / eLocation ID:
e1011120
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; (, MicroPublication)
    Microsporidia are common natural pathogens of the nematode Caenorhabditis elegans. Infection of C. elegans by the microsporidian species Nematocida parisii leads to induction of the Intracellular Pathogen Response (IPR), including transcriptional upregulation of 26 pals genes. The divergent ‘pals' sequence signature is conserved with humans, but PALS proteins have unknown biochemical functions. So far, none of the 26 induced pals genes have a demonstrated role in immunity. Here, we use RNAseq data, RNA interference, and CRISPR/Cas9 mutant analysis to identify the N. parisii-induced pals-14 gene as an immune gene that provides defense against microsporidia infection in C. elegans. 
    more » « less
  2. ; ; ; (, BioEssays)
    Abstract Although the type‐I interferon (IFN‐I) response is considered vertebrate‐specific, recent findings about the Intracellular Pathogen Response (IPR) in nematodeCaenorhabditis elegansindicate that there are similarities between these two transcriptional immunological programs. The IPR is induced during infection with natural intracellular fungal and viral pathogens of the intestine and promotes resistance against these pathogens. Similarly, the IFN‐I response is induced by viruses and other intracellular pathogens and promotes resistance against infection. Whether the IPR and the IFN‐I response evolved in a divergent or convergent manner is an unanswered and exciting question, which could be addressed by further studies of immunity against intracellular pathogens inC. elegansand other simple host organisms. Here we highlight similar roles played by RIG‐I‐like receptors, purine metabolism enzymes, proteotoxic stressors, and transcription factors to induce the IPR and IFN‐I response, as well as the similar consequences of these defense programs on organismal development. 
    more » « less
  3. ; ; ; (, PLOS Biology)
    Simon, Hans-Uwe (Ed.)
    Protein quality control pathways play important roles in resistance against pathogen infection. For example, the conserved transcription factor SKN-1/NRF up-regulates proteostasis capacity after blockade of the proteasome and also promotes resistance against bacterial infection in the nematodeCaenorhabditis elegans. SKN-1/NRF has 3 isoforms, and the SKN-1A/NRF1 isoform, in particular, regulates proteasomal gene expression upon proteasome dysfunction as part of a conserved bounce-back response. We report here that, in contrast to the previously reported role of SKN-1 in promoting resistance against bacterial infection, loss-of-function mutants inskn-1aand its activating enzymesddi-1andpng-1show constitutive expression of immune response programs against natural eukaryotic pathogens ofC.elegans. These programs are the oomycete recognition response (ORR), which promotes resistance against oomycetes that infect through the epidermis, and the intracellular pathogen response (IPR), which promotes resistance against intestine-infecting microsporidia. Consequently,skn-1amutants show increased resistance to both oomycete and microsporidia infections. We also report that almost all ORR/IPR genes induced in common between these programs are regulated by the proteasome and interestingly, specific ORR/IPR genes can be induced in distinct tissues depending on the exact trigger. Furthermore, we show that increasing proteasome function significantly reduces oomycete-mediated induction of multiple ORR markers. Altogether, our findings demonstrate that proteasome regulation keeps innate immune responses in check in a tissue-specific manner against natural eukaryotic pathogens of theC.elegansepidermis and intestine. 
    more » « less
  4. ; ; ; ; ; (, BMC Biology)
    Abstract BackgroundIn all organisms, the innate immune system defends against pathogens through basal expression of molecules that provide critical barriers to invasion and inducible expression of effectors that combat infection. The adenosine deaminase that act on RNA (ADAR) family of RNA-binding proteins has been reported to influence innate immunity in metazoans. However, studies on the susceptibility of ADAR mutant animals to infection are largely lacking. ResultsHere, by analyzingadr-1andadr-2null mutants in well-established slow-killing assays, we find that bothCaenorhabditis elegansADARs are important for organismal survival to gram-negative and gram-positive bacteria, all of which are pathogenic to humans. Furthermore, our high-throughput sequencing and genetic analysis reveal that ADR-1 and ADR-2 function in the same pathway to regulate collagen expression. Consistent with this finding, our scanning electron microscopy studies indicateadr-1;adr-2mutant animals also have altered cuticle morphology prior to pathogen exposure. ConclusionsOur data uncover a critical role of theC. elegansADAR family of RNA-binding proteins in promoting cuticular collagen expression, which represents a new post-transcriptional regulatory node that influences the extracellular matrix. In addition, we provide the first evidence that ADAR mutant animals have altered susceptibility to infection with several opportunistic human pathogens, suggesting a broader role of ADARs in altering physical barriers to infection to influence innate immunity. 
    more » « less
  5. ; ; ; ; ; ; (, Annual Review of Phytopathology)
    Gene silencing guided by small RNAs governs a broad range of cellular processes in eukaryotes. Small RNAs are important components of plant immunity because they contribute to pathogen-triggered transcription reprogramming and directly target pathogen RNAs. Recent research suggests that silencing of pathogen genes by plant small RNAs occurs not only during viral infection but also in nonviral pathogens through a process termed host-induced gene silencing, which involves trans-species small RNA trafficking. Similarly, small RNAs are also produced by eukaryotic pathogens and regulate virulence. This review summarizes the small RNA pathways in both plants and filamentous pathogens, including fungi and oomycetes, and discusses their role in host–pathogen interactions. We highlight secondarysmall interfering RNAs of plants as regulators of immune receptor gene expression and executors of host-induced gene silencing in invading pathogens. The current status and prospects of trans-species gene silencing at the host–pathogen interface are discussed. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email