Biology subjects

Lee, J. N.

Publications and source records attributed to Lee, J. N..

4 recordsLinked to original sources

bioRxiv2022

The Mangrove Microbiome of the Malay Peninsula

Microbes have fundamental roles underpinning the functioning of our planet, they are involved in global carbon and nutrient cycling, and support the existence of multicellular life. The mangrove ecosystem is nutrient limited and without microbial cycling, life in this harsh environment would likely not exist. The mangroves of Southeast Asia are the oldest and most biodiverse of all the planets. They have vital roles helping to prevent shoreline erosion, act as nursery grounds for many marine species and contain significant stocks of sequestered carbon. Despite these recognised benefits and the importance of microbes in these ecosystems, studies examining the mangrove microbiome are scarce, especially in the Southeast Asian biodiversity hotspot. Here we examine the microbiome of Avicenia alba and Sonneratia alba and identify a core microbiome of 81 taxa, a further eight taxa (Pleurocapsa, Tunicatimonas, Halomonas, Marinomonas, Rubrivirga, Altererythrobacte, Lewinella, and Erythrobacter) were found to be differentially abundant suggesting key roles in this microbiome, with the identified dimethylsulfoniopropionate (DMSP) metabolisers having important functions in these habitats. The majority of those identified are involved in nutrient cycling or involved in the production of compounds that promote host survival. Increasingly, blue carbon and nature-based solutions to climate change are heralded as viable mitigation steps to limit climate change, however, this is done with little to no consideration of the microbial communities that cycle sequestered carbon in these environments. Here, we examine the microbial communities present in sediment samples taken in close proximity to each tree, sediment samples represent a major sink of atmospheric carbon and understanding how the associated communities will change as climate change advances will become an increasingly important part of carbon stock assessments. Knowing what microbes are presently there is an important first step in this process.

ecology↗

bioRxiv2021

SIRT5 is the desuccinylase of LDHA as novel cancer metastatic stimulator in aggressive prostate cancer

Prostate cancer (PCa) is the most commonly diagnosed genital cancer in men worldwide. Among patients who developed advanced PCa, 80% suffered from bone metastasis, with a sharp drop in the survival rate. Despite great efforts, the details of the mechanisms underlying castration-resistant PCa (CRPC) remains unclear. SIRT5, an NAD+-dependent desuccinylase, is hypothesized to be a key regulator of various cancers. However, compared to other SIRTs, the role of SIRT5 in cancer has not been extensively studied. Here, we showed significantly decreased SIRT5 levels in aggressive PCa cells relative to the PCa stages. The correlation between the decrease in the SIRT5 level and the patients survival rate was also confirmed. Using quantitative global succinylome analysis, we characterized a significant increase of lysine 118 succinylation (K118su) of lactate dehydrogenase A (LDHA), which plays a role in increasing LDH activity. As a substrate of SIRT5, LDHA-K118su significantly increased the migration and invasion of PCa cells and LDH activity in PCa patients. This study investigated the reduction of SIRT5 and LDHA-K118su as a novel mechanism involved in PCa progression. It can also be proposed as a new target that can prevent castration-resistant PCa progression, which is key to PCa treatment.

cancer biology↗

bioRxiv2021

Single domain antibodies against enteric pathogen virulence factors are active as curli fiber fusions on probiotic E. coli Nissle 1917

Enteric microbial pathogens, including Escherichia coli, Shigella and Cryptosporidium species, take a particularly heavy toll in low-income countries and are highly associated with infant mortality. We describe here a means to display anti-infective agents on the surface of a probiotic bacterium. Because of their stability and versatility, VHHs, the variable domains of camelid heavy-chain-only antibodies, have potential as components of novel agents to treat or prevent enteric infectious disease. We isolated and characterized VHHs targeting several enteropathogenic Escherichia.coli (EPEC) virulence factors: flagellin (Fla), which is required for bacterial motility and promotes colonization; both intimin and the translocated intimin receptor (Tir), which together play key roles in attachment to enterocytes; and E. coli secreted protein A (EspA), an essential component of the type III secretion system (T3SS) that is required for virulence. Several VHHs that recognize Fla, intimin, or Tir blocked function in vitro. The probiotic strain E. coli Nissle 1917 (EcN) produces on the bacterial surface curli fibers, which are the major proteinaceous component of E. coli biofilms. A subset of Fla-, intimin-, or Tir-binding VHHs, as well as VHHs that recognize either a T3SS of another important bacterial pathogen (Shigella flexneri), a soluble bacterial toxin (Shiga toxin or Clostridioides difficile toxin TcdA), or a major surface antigen of an important eucaryotic pathogen (Cryptosporidium parvum) were fused to CsgA, the major curli fiber subunit. Scanning electron micrographs indicated CsgA-VHH fusions were assembled into curli fibers on the EcN surface, and Congo Red binding indicated that these recombinant curli fibers were produced at high levels. Ectopic production of these VHHs conferred on EcN the cognate binding activity and, in the case of anti-Shiga toxin, was neutralizing. Taken together, these results demonstrate the potential of the curli-based pathogen sequestration strategy described herein and contribute to the development of novel VHH-based gut therapeutics. Author SummaryEnteric pathogens are the causative agents of diarrheal disease - a leading cause of infant morbidity and mortality worldwide. While treatment and prevention options such as drugs or vaccines exist for some pathogens, their efficacy and availability are often limited. New therapeutic strategies are therefore needed, especially inexpensive agents in low-income countries where enteric disease burdens are highest. One promising avenue for novel treatments uses VHHs - highly stable, well-expressed, antibody domains derived from camelid species such as llamas and alpacas. The small size, high stability and simple structure of these antibody fragments enables their streamlined production by bacteria such as E. coli, potentially reducing cost and improving scalability. In this work, we describe the development of VHHs targeting multiple virulence factor proteins of pathogenic E. coli and other leading causes of diarrheal disease. These VHHs provide new tools for the research community and may serve as promising components of agents that prevent or treat pathogen infections. Towards that goal, we engineered a novel system in which the probiotic, mucus-establishing bacterial strain E. coli Nissle 1917 (EcN) is used to express and display VHHs at high density on its surface. By demonstrating the ability of these engineered EcN to bind to pathogens, we provide a first step toward using such probiotics as a cheap, simple, and effective treatment for enteric pathogen infections.

microbiology↗

bioRxiv2019

Extracellular adenosine enhances the ability of PMNs to kill Streptococcus pneumoniae by inhibiting IL-10 production

PMNs are crucial for initial control of Streptococcus pneumoniae (pneumococcus) lung infection; however, as the infection progresses their persistence in the lungs becomes detrimental. Here we explored why the anti-microbial efficacy of PMNs declines over the course of infection. We found that the progressive inability of PMNs to control infection correlated with phenotypic differences characterized by a decrease in CD73 expression, an enzyme required for production of extracellular adenosine (EAD). EAD production by CD73 was crucial for the ability of both murine and human PMNs to kill S. pneumoniae. In exploring the mechanisms by which CD73 controlled PMN function, we found that CD73 mediated its anti-microbial activity by inhibiting IL-10 production. PMNs from wild type mice did not increase IL-10 production in response to S. pneumoniae, however, CD73-/- PMNs up-regulated IL-10 production upon pneumococcal infection in vitro and during lung challenge. IL-10 inhibited the ability of wild type PMNs to kill pneumococci. Conversely, blocking IL-10 boosted the bactericidal activity of CD73-/- PMNs as well as host resistance of CD73-/- mice to pneumococcal pneumonia. CD73/IL-10 did not affect apoptosis, bacterial uptake and intracellular killing or production of anti-microbial Neutrophil Elastase and Myeloperoxidase. Rather, inhibition of IL-10 production by CD73 was important for optimal ROS production by PMNs. ROS contributed to PMN anti-microbial function as their removal or detoxification impaired the ability of PMNs to efficiently kill S. pneumoniae. This study demonstrates that CD73 controls PMN anti-microbial phenotype during S. pneumoniae infection.

immunology↗