An intestinally secreted host factor promotes microsporidia invasion of C. elegan

  1. Hala Tamim El Jarkass
  2. Calvin Mok
  3. Michael R Schertzberg
  4. Andrew G Fraser
  5. Emily R Troemel
  6. Aaron W Reinke  Is a corresponding author
  1. Department of Molecular Genetics, University of Toronto, Canada
  2. The Donnelly Centre, University of Toronto, Canada
  3. Division of Biological Sciences, University of California, San Diego, United States
7 figures, 1 table and 2 additional files

Figures

Figure 1 with 1 supplement
Mutations in aaim-1 result in resistance to N. parisii infection.

(a-c, and e) L1 stage wild-type (N2) and aaim-1 mutant animals were infected with either a high dose (a, b, and e) or a very lose dose (c) of N. parisii, fixed at 72 hr, and stained with …

Figure 1—source data 1

Mutations in aaim-1 result in resistance to N. parisii infection.

https://cdn.elifesciences.org/articles/72458/elife-72458-fig1-data1-v3.xlsx
Figure 1—figure supplement 1
Mapping and validation of aaim-1 as the gene associated with resistance to N. parisii.

(a) N2 or fawn animals were infected with a medium-3 dose of N. parisii spores on 6-cm plates, fixed at 72 hr, and stained with direct-yellow 96 (DY96). Graph displays percentage of gravid worms. …

Figure 1—figure supplement 1—source data 1

Mapping and validation of aaim-1 as the gene associated with resistance to N. parisii.

https://cdn.elifesciences.org/articles/72458/elife-72458-fig1-figsupp1-data1-v3.xlsx
Figure 2 with 2 supplements
AAIM-1 is secreted from intestinal cells.

(a) Wild-type worms containing an extrachromosomal array expressing GFP from the aaim-1 promoter and mCherry (labelled in magenta) in the pharyngeal muscles were imaged at the embryo, L1, L3, L4, …

Figure 2—figure supplement 1
AAIM-1 is conserved in both free-living and parasitic nematodes.

Phylogenetic tree of AAIM-1 homologs. Bootstrap values are shown at the nodes.

Figure 2—figure supplement 2
aaim-1 is expressed in arcade cells and presence of C-terminal 3 x Flag tag does not disrupt AAIM-1 function.

(a) N2 containing an extrachromosomal array expressing GFP from the aaim-1 promoter and mCherry (labelled in magenta) in the pharyngeal muscles were imaged at the L1 stage at 40 x. Scale bar 20 μm. …

Figure 2—figure supplement 2—source data 1

aaim-1 is expressed in arcade cells and presence of C-terminal 3 x Flag tag does not disrupt AAIM-1 function.

https://cdn.elifesciences.org/articles/72458/elife-72458-fig2-figsupp2-data1-v3.xlsx
Figure 3 with 2 supplements
aaim-1 mutants are resistant to microsporidia at the earliest larval stage due to spore misfiring.

(a–b) N2 and aaim-1 mutants were infected with a medium dose of N. ausubeli at either the L1 stage for 72 hr (a) or a high dose of N. ausubeli at the L3 stage for 48 hr (b) Graph displays percentage …

Figure 3—source data 1

aaim-1 mutants are resistant to microsporidia at the earliest larval stage due to spore misfiring.

https://cdn.elifesciences.org/articles/72458/elife-72458-fig3-data1-v3.xlsx
Figure 3—figure supplement 1
aaim-1 mutants do not clear N. parisii and developmentally restricted N. parisii invasion defect is not due to a feeding defect.

(a–b) N2 and aaim-1 mutants were infected at either the L1 stage (a) or the L3 stage (b) with a medium-1 dose of N. parisii spores for 3 hr. Animals were then washed to remove spores and re-plated …

Figure 3—figure supplement 1—source data 1

aaim-1 mutants do not clear N. parisii and developmentally restricted N. parisii invasion defect is not due to a feeding defect.

https://cdn.elifesciences.org/articles/72458/elife-72458-fig3-figsupp1-data1-v3.xlsx
Figure 3—figure supplement 2
Invasion defects in aaim-1 only occur at the L1 stage of development and a mutation in aaim-1 does not alter the width of the intestinal lumen.

(a–f) N2 and aaim-1 animals were infected for 3 hr at L1 (a–c) or L3 (d-f), fixed, and then stained with DY96 and an N. parisii 18 S RNA fish probe. The number of spores per animal (a,d) the …

Figure 3—figure supplement 2—source data 1

Invasion defects in aaim-1 only occur at the L1 stage of development and a mutation in aaim-1 does not alter the width of the intestinal lumen.

https://cdn.elifesciences.org/articles/72458/elife-72458-fig3-figsupp2-data1-v3.xlsx
Spores in aaim-1 mutants display improper orientation and distance to the apical intestinal membrane.

(a–e) PGP-1::GFP and aaim-1(kea22); PGP-1::GFP animals were infected with a very high dose of calcofluor white (CFW) pre-stained N. parisii spores for 45 min at either the L1 stage (a–c) or the L3 …

Figure 4—source data 1

Spores in aaim-1 mutants display improper orientation and distance to the apical intestinal membrane.

https://cdn.elifesciences.org/articles/72458/elife-72458-fig4-data1-v3.xlsx
Figure 5 with 2 supplements
aaim-1 is upregulated by N. parisii and P. auerginosa and aaim-1 animals are susceptible to infection by P. aeruginosa.

(a) Expression of paaim-1::GFP::3xFlag in response to infection with either PA14 or N. parisii for either 72 hr from L1 or 24 hr from L4. Data is from three independent replicates of at least 18–25 …

Figure 5—source data 1

aaim-1 is upregulated by N. parisii and P. auerginosa and aaim-1 animals are susceptible to infection by P. aeruginosa.

https://cdn.elifesciences.org/articles/72458/elife-72458-fig5-data1-v3.xlsx
Figure 5—figure supplement 1
Susceptibility to P. aeruginosa PA14 appears at L4.

(a,b) Additional replicates of survival assays of animals grown on full lawns of PA14::DsRed as in Figure 5a. (a) TD50: N2 51 hr, aaim-1 (kea28) 46 hr, aaim-1 (kea22) 38 hr, and pmk-1 (km25) 25 hr. …

Figure 5—figure supplement 1—source data 1

Susceptibility to P. aeruginosa PA14 appears at L4.

https://cdn.elifesciences.org/articles/72458/elife-72458-fig5-figsupp1-data1-v3.xlsx
Figure 5—figure supplement 2
A mutation in aaim-1 does not influence C. elegans defense against S. aureus or lifespan.

(a) L4 stage N2 and aaim-1 were plated on full lawns of S. aureus NCTC8325 and the percentage of animals alive was counted over the course of 120 hr. Three independent replicates are displayed. At …

Figure 5—figure supplement 2—source data 1

A mutation in aaim-1 does not influence C. elegans defense against S. aureus or lifespan.

https://cdn.elifesciences.org/articles/72458/elife-72458-fig5-figsupp2-data1-v3.xlsx
Figure 6 with 1 supplement
aaim-1 alleles display enhanced fitness on N. parisii, but reduced fitness on P. aeruginosa.

(a) Competitive fitness assays performed with a fluorescently marked strain (RFP::ZNFX1) mixed with either N2 or aaim-1 mutants. These mixed populations of animals were plated at the L1 stage on …

Figure 6—source data 1

aaim-1 alleles display enhanced fitness on N. parisii, but reduced fitness on P. aeruginosa.

https://cdn.elifesciences.org/articles/72458/elife-72458-fig6-data1-v3.xlsx
Figure 6—figure supplement 1
List of naturally occurring aaim-1(T14E8.4) variants in wild isolates of C. elegans.

This table represents a list of aaim-1 coding variants found to naturally occur in wild isolates of C. elegans gnerated by the CeNDR variant browser (Cook et al., 2017). The reference allele (REF) …

Secreted AAIM-1 functions in the intestinal lumen to limit bacterial colonization but is exploited by microsporidia to ensure successful invasion of intestinal cells.

AAIM-1 is secreted from intestinal cells, where the protein limits bacterial colonization in the lumen. Additionally, AAIM-1 is parasitized by N. parisii spores to ensure successful orientation and …

Tables

Appendix 1—key resources table
Reagent type (species) or resourceDesignationSource or referenceIdentifiersAdditional information
Gene (Caenorhabditis elegans)aaim-1This paperT14E8.4Wormbase ID:
WBGene00043981
Genetic reagent (Caenorhabditis elegans)N2Caenorhabditis genetic center (CGC)N2 RRID:SCR_007341Wild-type, Bristol strain.
Genetic reagent (Caenorhabditis elegans)fawn-1 (AWR 05)This paperaaim-1 (kea89) XC127T, Q43Stop
Genetic reagent (Caenorhabditis elegans)fawn-2 (AWR 11)This paperaaim-1 (kea28) X2.2 kb deletion
Genetic reagent (Caenorhabditis elegans)fawn-3 (AWR 17)This paperaaim-1 (kea91) XG221A splice site mutation
Genetic reagent (Caenorhabditis elegans)fawn-4 (AWR 03)This paperaaim-1 (kea103) XC1286T, A429V
Genetic reagent (Caenorhabditis elegans)DM7748Mok et al., 2020 DOI: 10.1534/g3.120.401656.VC20019 (Ex[Pmyo-3::YFP])Mapping strain
Genetic reagent (Caenorhabditis elegans)RB563Caenorhabditis genetic center (CGC)aaim-1 (ok295) XLarge gene deletion in aaim-1 and neighbouring gene dop-3
Genetic reagent (Caenorhabditis elegans)AWR 73This paperaaim-1 (kea22) X3 x outcrossed CRISPR-Cas9 generated deletion allele of aaim-1.
Genetic reagent (Caenorhabditis elegans)AWR 83This paperaaim-1 (kea28) X6 x outcrossed fawn-2 (kea28)
Genetic reagent (Caenorhabditis elegans)DA465Caenorhabditis genetic center (CGC)eat-2 (ad465) IIFeeding defective mutant.
Genetic reagent (Caenorhabditis elegans)AWR 131This paperN2 Ex[pmyo2::mCherry::Unc54, paaim-1::GFP::3xFlag::Unc54]aaim-1 transcriptional reporter in N2 background with a pharyngeal mCherry co-injection marker.
Genetic reagent (Caenorhabditis elegans)AWR 125This paperaaim-1(kea22 Ex[pmyo2::mCherry::Unc54, paaim-1::GFP::3xFlag::Unc54])aaim-1 transcriptional reporter in aaim-1 (kea22) mutant background with a pharyngeal mCherry co-injection marker.
Genetic reagent (Caenorhabditis elegans)AWR 122This paperaaim-1(kea22 Ex[pmyo3::mCherry::Unc54, paaim-1::GFP::Unc54])aaim-1 transcriptional reporter in aaim-1 (kea22) mutant background with a body wall muscle mCherry co-injection marker.
Genetic reagent (Caenorhabditis elegans)AWR 115This paperaaim-1 (kea22 Ex[pmyo2::mCherry::Unc54, paaim-1::aaim-1::Unc54])aaim-1 over expression in an aaim-1 (kea22) mutant background with a pharyngeal mCherry co-injection marker.
Genetic reagent (Caenorhabditis elegans)AWR119This paperaaim-1 (kea22 Ex[pmyo2::mCherry::Unc54, paaim-1::aaim-1::3xFlag::Unc54])aaim-1::3xFlag over expression in an aaim-1 (kea22) mutant background with a pharyngeal mCherry co-injection marker.
Genetic reagent (Caenorhabditis elegans)AWR 127This paperaaim-1 (kea22 Ex[pmyo2::mCherry::Unc54, paaim-1::SPΔ aaim-1::3xFlag::Unc54])Signal peptide mutant aaim-1::3xFlag over expression in an aaim-1 (kea22) mutant background with a pharyngeal mCherry co-injection marker.
Genetic reagent (Caenorhabditis elegans)AWR129This paperaaim-1 (kea22 Ex[pmyo2::mCherry::Unc54, pspp-5:: aaim-1::3xFlag::Unc54])Intestinal aaim-1::3xFlag over expression in an aaim-1 (kea22) mutant background with a pharyngeal mCherry co-injection marker.
Genetic reagent (Caenorhabditis elegans)YY1446Caenorhabditis genetic center (CGC)znfx-1(gg634[HA::tagRFP::znfx-1]) II.RFP germ granules
Genetic reagent (Caenorhabditis elegans)GK288Sato et al., 2007 DOI: 10.1038/nature05929unc-119(ed3); dkIs166[popt-2::PGP-1::GFP, unc-119(+)]Apical intestinal membrane marker.
Genetic reagent (Caenorhabditis elegans)KU25Caenorhabditis genetic center (CGC)pmk-1 (km25) IVp38 Map kinase loss of function mutant.
Genetic reagent (Caenorhabditis elegans)AWR182This paperaaim-1 (kea22) X; dkIs166[popt-2::PGP-1::GFP, unc-119(+)] IVaaim-1 (kea22) mutant allele crossed into GK288.
Genetic reagent (Escherichia coli)OP50-1Caenorhabditis genetic center (CGC)OP50-1Uracil auxotroph. B strain. Streptomycin resistant.
Genetic reagent (Escherichia coli)5-alpha competent E. coliNew England Biolabs (NEB)Cat#: C2987HE. coli background in which transformations for molecular cloning were performed.
Genetic reagent (Nematocida parisii)N. parisii (ERTm1)This paperN. parisii (ERTm1)Nematode intestinal infecting species of microsporidia.
Genetic reagent (Nematocida ausubeli)N. ausubeli (ERTm2)This paperN. ausubeli (ERTm2)Nematode intestinal infecting species of microsporidia.
Genetic reagent (Pseudomonas aeruginosa)PA14::DsRedDunn et al., 2006 DOI: 10.1128/AEM.72.1.802810.2006PA14::DsRedDsRed labelled strain of PA14.
Genetic reagent (Staphylococcus aureus)NCTC 8325Sifri et al., 2003 DOI: 10.1128/IAI.71.4.2208–2217.2003NCTC 8325S. aureus isolate used for C. elegans killing assays.
AntibodyM2 anti Flag (Mouse monoclonal)SigmaCat#: F1804 RRID:AB_262044IF (1:250)
AntibodyAnti mouse Alexafluor 594 (Goat polyclonal)Thermo FisherCat#: A32742 RRID:AB_2762825IF (1:300)
Sequence-based reagentReverse primerIntegrated DNA technologies (IDT)Reverse primer to amplify aaim-15’-ttaatttttttgctggtgagg-3’
Sequence-based reagentForward primerIntegrated DNA technologies (IDT)Forward primer to generate SPΔaaim-15'-atgctaaaggatttcttgccgtg-3'
Sequence-based reagentForward primerIntegrated DNA technologies (IDT)Forward primer to amplify paaim-15'-ttagtttggaaatgcacaaaaaaactgatctct-3'
Sequence-based reagentReverse primerIntegrated DNA technologies (IDT)Reverse primer to amplify paaim-15-cagtggacttctgcttattaaaatgacttc-3'
Sequence-based reagentForward primerIntegrated DNA technologies (IDT)Forward primer to amplify pmyo25'-cattttatatctgagtagtatcctttgctttaaatgtcc-3'
Sequence-based reagentReverse primerIntegrated DNA technologies (IDT)Reverse primer to amplify pmyo25’- gcatttctgtgtctgacgat-3'
Sequence-based reagentForward primerIntegrated DNA technologies (IDT)Forward primer to amplify pspp55’-aaagcaaaatatcattatttgggaaaatc-3’
Sequence-based reagentReverse primerIntegrated DNA technologies (IDT)Reverse primer to amplify pspp55’-tctgtaataaaataaattgaaatgaaacac-3’
Sequence-based reagentForward primerIntegrated DNA technologies (IDT)Forward primer to amplify GFP from pDD2825'-atgagtaaaggagaagaattgttcact-3'
Sequence-based reagentReverse primerIntegrated DNA technologies (IDT)Reverse primer to amplify GFP from pDD2825'-ttacttgtagagctcgtccattccg-3'
Sequence-based reagentForward UltramerIntegrated DNA technologies (IDT)Forward ultramer to add a Gly Ala Gly Ser linker and 3 x Flag with stop codon to C-Terminal end of constructs in pDDONR221 via round the horn PCR.55’-ggagccggatctgattataaagacgatgacgataagcgtgactacaaggacgacgacgaca agcgtgattacaaggatgacgatgacaagagataaacccagctttcttgtacaaagttg-3’
Sequence-based reagentMicroB FISH probe conjugated to Cal Fluor 610LGC Biosearch Technologies18 s RNA FISH probe5’-ctctcggcactccttcctg-3’
Sequence-based reagentAlt-R CRISPR-Cas9 tracrRNA 5 nmolIntegrated DNA technologies (IDT)Cat#: 1072532
Sequence-based reagent5’ sgRNAIntegrated DNA technologies (IDT)Guide RNA5'-aataaatggcataagttaag-3'
Sequence-based reagent3’ sgRNAIntegrated DNA technologies (IDT)Guide RNA5'-tttacaggcgtgtttcattg-3'
Recombinant proteinAlt-R S.p. Cas9 Nuclease V3, 100 ugIntegrated DNA technologies (IDT)Cat#: 1081058
Recombinant proteinPhusion High-Fidelity DNA PolymeraseNew England Biolabs (NEB)Cat#: M0530LDNA polymerase used for all molecular cloning steps.
Recombinant DNA reagentpBSKPonchon et al., 2009 DOI: 10.1038/nprot.2009.67.pBSK RRID:Addgene_67504Addgene ID: 67,504
Recombinant DNA reagentGateway pDONR221InvitrogenCat#: 12536017
Recombinant DNA reagentpCFJ90Frøkjaer-Jensen et al., 2008 DOI: 10.1038/ng.248.pCFJ90 RRID:Addgene_19327Addgene ID: 19,327
Recombinant DNA reagentpDD282Dickinson et al., 2015 DOI: 10.1534/genetics.115.178335.pDD282 RRID:Addgene_66823Addgene ID: 66,823
Commercial assay or kitNEBuilder HiFi DNA assemblyNew England biolabs (NEB)Cat#: 3E2621Kit used for Gibson assembly.
Commercial assay or kitMonarch PCR and DNA Cleanup KitNew England biolabs (NEB)Cat#: T1030SPCR purification kit for amplicons used in downstream molecular cloning steps.
Commercial assay or kitQIAprep spin miniprep kitQiagenCat#: 27,106Kit used for extraction of DNA from bacterial clones.
Chemical compound, drugDirect yellow 96Sigma- AldrichCat#: S472409-1GChitin binding dye.
Chemical compound, drugCalcofluor whiteSigma- AldrichCat#: 18,909Chitin binding dye.
Chemical compound, drugEverbriteMounting MediumBiotiumCat#: 23,002Mounting medium with DAPI
Software, algorithmFIJISchindelin et al., 2012 DOI: 10.1038/nmeth.2019RRID:SCR_002285Image analysis software
Software, algorithmGraphPad Pism 9.0GraphPad Pism 9.0RRID:SCR_002798Statistical analysis software
Other0.2 μm green fluorescent polystyrene beadsDegradex PhosphorexCat#: 2,108BFluorescent beads for bead feeding assays.

Additional files

Supplementary file 1

Spore doses utilized in this study.

The different species of microsporidia used in the study, and the varying doses (as defined in figure legends) are listed. Plate concentration refers to the number of spores occupied per cm2 of either 3.5, 6, or 10 cm NGM plates (indicated by *, ** or *** in the ‘total spores on assay plate’ column). The total number of spores present on a single assay plate are listed for the various doses in millions of spores.

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