Biology subjects

Morris, S. C.

Publications and source records attributed to Morris, S. C..

4 recordsLinked to original sources

bioRxiv2026

A moonlighting serpin of Tannerella forsythia compromises the bactericidal activity of neutrophils

Serine protease inhibitors (serpins) are extremely rare in prokaryotes, and their role in immune evasion remains unclear. We identified a bifunctional TLR2-binding serpin (miropin) produced by Tannerella forsythia that broadly suppresses neutrophil antimicrobial capacity. Miropin binding to TLR2 primed neutrophils, enhancing phagocytic capacity yet, counterintuitively, promoting bacterial persistence. Mechanistically, like other serpins, miropin acted as an irreversible suicide inhibitor of neutrophil serine proteases (NSPs), blocking their activity upon granule mobilization and NETosis. Unexpectedly, miropin, independent of its protease-inhibitory activity, bound and inhibited myeloperoxidase (MPO), thereby blocking the oxidative burst. This simultaneous suppression of oxidative and non-oxidative bactericidal mechanisms promoted bacterial survival in vivo without significantly altering the tissue inflammatory response. Thus, we identified novel moonlighting roles (TLR2 signaling and MPO inhibition) for an unorthodox prokaryotic serpin and provided context for how T. forsythia and other oral pathogens survive within the subgingival niche, an environment highly enriched in activated neutrophils.

immunology↗

bioRxiv2024

Natural selection exerted by historical coronavirus epidemic(s): comparative genetic analysis in China Kadoorie Biobank and UK Biobank

BackgroundPathogens have been one of the primary sources of natural selection affecting modern humans. The footprints of historical selection events - "selective sweeps" - can be detected in the genomes of present-day individuals. Previous analyses of 629 samples from the 1000 Genomes Project suggested that an ancient coronavirus epidemic [~]20,000 years ago drove multiple selective sweeps in the ancestors of present-day East Asians, but not in other worldwide populations. ResultsUsing a much larger genetic dataset of 76,719 unrelated individuals from each of the China Kadoorie Biobank (CKB) and UK Biobank (UKB) to identify regions of long-range linkage disequilibrium, we further investigated signatures of past selective sweeps and how they reflect previous viral epidemics. Using independently-curated lists of human host proteins which interact physically or functionally with viruses (virus-interacting proteins; VIPs), we found enrichment in CKB for regions of long-range linkage disequilibrium at genes encoding VIPs for coronaviruses, but not DNA viruses. By contrast, we found no clear evidence for any VIP enrichment in UKB. These findings were supported by additional analyses using saltiLASSi, a selection-scan method robust to false positives caused by demographic events. By contrast, for GWAS signals for SARS-Cov2 susceptibility (critical illness, hospitalisation, and reported infection), there was no difference between UKB and CKB in the number located at or near signals of selection, as expected for a novel virus which has had no opportunity to impact the CKB/UKB study populations. ConclusionsTogether, these results provide evidence of selection events consistent with historical coronavirus epidemic(s) originating in East Asia. These results show how biobank-scale datasets and evolutionary genomics theory can provide insight into the study of past epidemics. The results also highlights how historic infectious diseases epidemics can shape the genetic architecture of present-day human populations.

genomics↗

bioRxiv2022

The GC box at the proximal enhancer of the Hdc gene is critical for Hdc gene transcription and histamine-mediated anaphylaxis

Background: Histamine is a critical mediator of anaphylaxis, a neurotransmitter, and a regulator of gastric acid secretion. Histidine decarboxylase is a rate-limiting enzyme for histamine synthesis. However, in vivo regulation of Hdc, the gene that encodes histidine decarboxylase is poorly understood. Objective: We sought to investigate how enhancers regulate Hdc gene transcription and histamine synthesis in resting conditions and in a mouse model of anaphylaxis. Methods: H3K27 acetylation histone modification and chromatin accessibility were used to identify candidate enhancers; The enhancer activity of candidate enhancers was measured in a reporter gene assay; and the function enhancers were validated using CRISPR deletion. Results: Deletion of the GC box, which binds to zinc finger transcription factors, in the proximal Hdc enhancer, reduced Hdc gene transcription and histamine synthesis in the mouse and human mast cell lines. Mast cells, basophils, brain cells, and stomach cells from GC box-deficient mice transcribed the Hdc gene much less than similar cells from wild-type mice and Hdc GC box-deficient mice failed to develop anaphylaxis. Conclusion: Our results demonstrate that the HDC GC box within the proximal enhancer in the mouse and human HDC gene is essential for Hdc gene transcription, histamine synthesis, and histamine-mediated anaphylaxis in vitro and in vivo. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=104 SRC="FIGDIR/small/495950v3_ufig1.gif" ALT="Figure 1"> View larger version (40K): org.highwire.dtl.DTLVardef@106f99org.highwire.dtl.DTLVardef@10ec8b8org.highwire.dtl.DTLVardef@19bb1ceorg.highwire.dtl.DTLVardef@b663cd_HPS_FORMAT_FIGEXP M_FIG C_FIG Key messages: O_LIThe HDC GC box within the proximal enhancer of the mouse and human HDC gene is essential for Hdc gene transcription and histamine synthesis in mouse and human mast cells. C_LIO_LIThe mouse Hdc GC box is required for histamine-mediated anaphylaxis in vivo. C_LI Capsule summary Our results demonstrate that the Hdc GC box within the proximal enhancer of the mouse and human HDC gene is essential for Hdc gene transcription and histamine synthesis in mast cells. The mouse Hdc GC box is required for histamine-mediated anaphylaxis in the mouse model of anaphylaxis.

immunology↗

bioRxiv2022

The TOG protein Stu2 is regulated by acetylation

Stu2 in S. cerevisiae is a member of the XMAP215/Dis1/Alp14/Msps/CKAP5/ch-TOG family of MAPs and has multiple functions in controlling microtubules, including microtubule polymerization, microtubule depolymerization, linking chromosomes to the kinetochore, and assembly of {gamma}-TuSCs at the SPB. Whereas phosphorylation has been shown to be critical for Stu2 localization at the kinetochore, other regulatory mechanisms that control Stu2 function are still poorly understood. Here, we show that a novel form of Stu2 regulation occurs through the acetylation of three lysine residues at K252, K469, and K870, which are located in three distinct domains of Stu2. Alteration of acetylation through acetyl-mimetic and acetyl-blocking mutations did not impact the essential function of Stu2. Instead, these mutations lead to both positive and negative changes in chromosome stability, as well as changes in resistance to the microtubule depolymerization drug, benomyl. In agreement with our in silico modeling, several acetylation-mimetic mutants displayed increased interactions with {gamma}-tubulin. Taken together, these data suggest that Stu2 acetylation can govern multiple Stu2 functions in both a positive and negative manner, including chromosome stability and interactions at the SPB.

genetics↗