Biology subjects

Tomlinson, L.

Publications and source records attributed to Tomlinson, L..

5 recordsLinked to original sources

bioRxiv2025

Antifungal exposure can enhance Candida glabrata pathogenesis

Azole antifungal drugs directly inhibit lanosterol 14-[a]-demethylase and indirectly affect the expression of metabolic, transmembrane transporter, and cell wall organization genes in fungal pathogens. It is not known how these indirect azole effects depend on dose, timing, and specific azole used, or how they influence host interactions. Candida glabrata (recently renamed Nakaseomyces glabratus) is the second leading cause of candidiasis, and clinical strains have high rates of intrinsic resistance to azoles. We investigated the early responses of reference strains BG2 and CBS138 to sub-inhibitory doses of fluconazole and voriconazole, and particularly, how these responses affect host-pathogen interactions. Cell wall profiling and transcriptomic data revealed highly similar responses for each strain to both azoles, including the upregulation of several virulence factors, such as yapsins. We also observed significant increases in CBS138 survival in macrophages and increased virulence in Galleria mellonella after voriconazole exposure. Using a combination of pharmacological inhibition of calcium ion channels and deletion strains, we determined that voriconazole-enhanced virulence requires a yapsin protease, YPS1, and is regulated via the calcineurin pathway and the cell wall integrity pathway, both of which regulate YPS1 expression. We also observed that voriconazole treatment significantly reduced the virulence of the bck1{Delta} strain in G. mellonella, suggesting that inhibitors of the cell wall integrity pathway might potentiate azole activity by improving susceptibility to host killing. Our study provides new insight into short-term azole adaptation in C. glabrata, and importantly demonstrates that sub-inhibitory azole exposure can induce virulence factors and alter fungal pathogenesis. Article summaryAntifungal drugs indirectly affect essential fungal cell processes, but we lack an understanding of how drug-induced changes affect fungal pathogenesis. We investigated how Candida glabrata adapts when exposed to azole drugs in terms of cell wall and transcriptional changes. Reference strains had similar transcriptional changes in response to azoles, but azole-treated CBS138 survived better in immune cells and caused more host death than untreated cells, suggesting that short-term azole treatment can significantly affect pathogenesis. Voriconazole-enhanced disease requires the calcineurin and cell wall integrity pathways and the virulence factor, YPS1, but could be blocked by a calcium ion channel inhibitor. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=110 SRC="FIGDIR/small/667834v1_ufig1.gif" ALT="Figure 1"> View larger version (29K): org.highwire.dtl.DTLVardef@157eaforg.highwire.dtl.DTLVardef@13050c0org.highwire.dtl.DTLVardef@10593d0org.highwire.dtl.DTLVardef@12b663e_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2020

Discovery and fine-mapping of kidney function loci in first genome-wide association study in Africans

Genome-wide association studies (GWAS) for kidney function have uncovered hundreds of risk loci, primarily in populations of European ancestry. We conducted the first GWAS of estimated glomerular filtration rate (eGFR) in Africa in 3288 Ugandans and replicated the findings in 8224 African Americans. We identified two loci associated with eGFR at genome-wide significance (p<5x10-8). The most significantly associated variant (rs2433603, p=2.4x10-9) in GATM was distinct from previously reported signals. A second association signal mapping near HBB (rs141845179, p=3.0x10-8) was not significant after conditioning on a previously reported SNP (rs334) for eGFR. However, fine-mapping analyses highlighted rs141845179 to be the most likely causal variant at the HBB locus (posterior probability of 0.61). A trans-ethnic GRS of eGFR constructed from previously reported lead SNPs was not predictive into the Ugandan population, indicating that additional large-scale efforts in Africa are necessary to gain further insight into the genetic architecture of kidney disease.

genetics↗

bioRxiv2020

A complex resistance locus in Solanum americanum recognizes a conserved Phytophthora effector

Late blight caused by Phytophthora infestans greatly constrains potato production. Many Resistance (R) genes were cloned from wild Solanum species and/or introduced into potato cultivars by breeding. However, individual R genes have been overcome by P. infestans evolution; durable resistance remains elusive. We positionally cloned a new R gene, Rpi-amr1, from Solanum americanum, that encodes an NRC helper-dependent CC-NLR protein. Rpi-amr1 confers resistance in potato to all 19 P. infestans isolates tested. Using association genomics and long-read RenSeq, we defined eight additional Rpi-amr1 alleles from different S. americanum and related species. Despite only [~]90% identity between Rpi-amr1 proteins, all confer late blight resistance but differentially recognize Avramr1 orthologs and paralogs. We propose that Rpi-amr1 gene family diversity facilitates detection of diverse paralogs and alleles of the recognized effector, enabling broad-spectrum and durable resistance against P. infestans.

plant biology↗

bioRxiv2019

Estradiol-inducible AvrRps4 expression reveals distinct properties of TIR-NLR-mediated effector-triggered immunity

Plant nucleotide-binding domain, leucine-rich repeat receptor (NLR) proteins play important roles in recognition of pathogen-derived effectors. However, the mechanism by which plant NLRs activate immunity is still largely unknown. The paired Arabidopsis NLRs RRS1-R and RPS4, that confer recognition of bacterial effectors AvrRps4 and PopP2, are well studied, but how the RRS1/RPS4 complex activates early immediate downstream responses upon effector detection is still poorly understood. To study RRS1/RPS4 responses without the influence of cell-surface receptor immune pathways, we generated an Arabidopsis line with inducible expression of effector AvrRps4. Induction does not lead to hypersensitive cell death response (HR) but can induce electrolyte leakage, which often correlates with plant cell death. Activation of RRS1 and RPS4 without pathogens cannot activate mitogen-associated protein kinase cascades, but still activates upregulation of defense genes, and therefore resistance against bacteria.\n\nHighlightInducible expression of AvrRps4 activates RRS1/RPS4-mediated effector-triggered immunity without the presence of pathogens, allowing us to characterise downstream immune responses triggered by TIR-NLRs without cell-surface receptor-mediated immunity.

plant biology↗

bioRxiv2018

Optimization of T-DNA architecture for Cas9-mediated mutagenesis in Arabidopsis

Bacterial CRISPR systems have been widely adopted to create operator-specified site-specific nucleases. Such nuclease action commonly results in loss-of-function alleles, facilitating functional analysis of genes and gene families We conducted a systematic comparison of components and T-DNA architectures for CRISPR-mediated gene editing in Arabidopsis, testing multiple promoters, terminators, sgRNA backbones and Cas9 alleles. We identified a T-DNA architecture that usually results in stable (i.e. homozygous) mutations in the first generation after transformation. Notably, the transcription of sgRNA and Cas9 in head-to-head divergent orientation usually resulted in highly active lines. Our Arabidopsis data may prove useful for optimization of CRISPR methods in other plants.

plant biology↗