Biology subjects

Cen, L.

Publications and source records attributed to Cen, L..

3 recordsLinked to original sources

bioRxiv2022

Targeting Fusobacterium nucleatum through Chemical Modifications of Host-Derived Transfer RNA Fragments

Host mucosal barriers possess an arsenal of defense molecules to maintain mucosal health. In addition to well-established defense molecules such as antimicrobial peptides and immunoglobulins, a subset of extracellular host-derived small RNAs (sRNAs) also exhibits antimicrobial functions in a cross-kingdom fashion. We recently uncovered the sRNA-mediated crosstalk between human normal oral keratinocytes and Fusobacterium nucleatum (Fn), an opportunistic oral pathobiont with increasing implications in extra-oral diseases. Notably, when challenged with Fn, oral keratinocytes released Fn-targeting tRNA-derived sRNAs (tsRNAs), an emerging class of noncoding sRNAs with diverse functions in gene regulation. Additionally, synthetic mimics of the Fn-targeting tsRNAs exhibited highly selective antimicrobial activity against Fn. However, excess synthetic tsRNAs (in the micromolar range) were required to achieve growth inhibition, which limits their potential as antimicrobials. Here, we chemically modify nucleotides of the anti-Fn tsRNAs, termed MOD-tsRNAs, and demonstrate their species- and sequence-specific inhibition in the nanomolar range in various Fn type strains and clinical tumor isolates. In contrast, the same MOD-tsRNAs do not inhibit two representative oral bacteria, Porphoromonas gingivalis (Pg) and Streptococcus mitis (Sm). Additionally, MOD-tsRNAs are internalized by different Fn strains while exhibiting minimal uptake by Pg and Sm. Further RNA sequencing and affinity pull-down assays implicate MOD-tsRNAs as potential ribosome-targeting antimicrobials against Fn. Taken together, our work provides a framework to target opportunistic pathobionts through co-opting host-derived extracellular tsRNAs, whose potential applications may have been limited by their intrinsic instability as well as our limited understanding of the inhibition mechanism.

bioengineering↗

bioRxiv2022

Transcriptome of epibiont Saccharibacteria Nanosynbacter lyticus strain TM7x during establishment of symbiosis

Saccharibacteria Nanosynbacter lyticus strain TM7x is a member of the broadly distributed Candidate Phylum Radiation. These bacteria have ultrasmall cell size, reduced genomes and live as epibionts on the surface of other bacteria. The mechanisms by which they establish and maintain this relationship are not yet fully understood. The transcriptomes of the epibiont TM7x and its host bacteria Schaalia odontolyticus strain XH001 were captured across the establishment of symbiosis during both the initial interaction and stable symbiosis. The results showed a dynamic interaction with large shifts in gene expression for both species between the initial encounter and stable symbiosis, notably transporter genes. During stable symbiosis, the host XH001 showed higher gene expression for peptidoglycan biosynthesis, mannosylation, cell cycle and stress related genes, but lower expression of chromosomal partitioning genes. This was consistent with the elongated cell shape seen in XH001 infected with TM7x and our discovery that infection resulted in thickened cell walls. Within TM7x, increased pili, type IV effector gene, and arginine catabolism/biosynthesis gene expression during stable symbiosis implied a key role for these functions in the interaction. Consistent with its survival and persistence in the human microbiome as an obligate epibiont with reduced de novo biosynthetic capacities, TM7x also showed higher levels for energy production and peptidoglycan biosynthesis but lower expression of stress related genes during stable symbiosis. These results imply that TM7x and its host bacteria keep a delicate balance in order to sustain an episymbiotic lifestyle. IMPORTANCENanosynbacter lyticus type strain TM7x is the first cultivated member of the Saccharibacteria and the Candidate Phyla Radiation (CPR). It was discovered to have ultrasmall cell size with a highly reduced genome that establishes an obligate epibiotic relationship with its host bacterium. The CPR, now formally proposed as the Patescibacteria super-phylum, is a large monophyletic radiation of diverse bacteria with reduced genomes that includes Saccharibacteria. The vast majority of the CPR have yet to be cultivated in the laboratory and our insights into these unique organisms to date has been derived from only a few Saccharibacteria species. It is unknown however how these small obligate parasitic Saccharibacteria, that are missing many de novo biosynthetic pathways, are maintained at high prevalence within the human microbiome as well as in the environment. When TM7x infects its host bacterium there are distinct temporal phases, including an initial interaction, a killing phase, recovery phase, and finally stable symbiosis. Here we captured the gene expression of the host bacterium and epibiont during this dynamic interaction which represents the initial insights into the mechanisms of how these unique microbes may survive and persist.

microbiology↗

bioRxiv2021

The immunomodulatory properties of the HDAC6 inhibitor ACY241 supports robust anti-tumor response in NSCLC when coupled with the chemotherapy drug Oxaliplatin

BackgroundDurable treatments that benefit a wide pool of patients remain elusive for Non-small cell lung cancer (NSCLC). The success of immunotherapy in a subset of NSCLC patients highlights the potential contribution of immune response to anti-tumor immunity while underscoring a need for broadly applicable therapeutic strategies. HDAC inhibitors are a promising class of drugs whose immunomodulatory properties are now being appreciated. In the present study, we evaluated the effects of the HDAC6 inhibitor, ACY241 on lung tumor immune compartment with the goal of understanding the scope of its immunomodulatory properties and its therapeutic potential in combination with Oxaliplatin. MethodsLung adenocarcinoma-bearing mice were treated with ACY241 or vehicle after which the proportions and phenotype of tumor-associated T cells and macrophages were evaluated by comprehensive flow cytometric analysis. Bulk RNA-sequencing was also conducted on both cellular subsets to interrogate the transcriptomic changes associated with ACY241 treatment relative to vehicle controls. In vivo drug efficacy study was performed by administration of ACY241 and/or Oxaliplatin and assessing tumor growth and survival of tumor-bearing mice. Ex vivo functional studies was performed to assess tumor-associated T cell effector function as it correlates with measured outcomes. ResultsWe demonstrate that ACY241 promotes increased presence of T and NK cells in the lung tumors of treated mice. The tumor-associated T cells under ACY241 treatment displayed enhanced activation, proliferation, and effector profile. In addition, tumor-associated macrophages exhibited increased expression of MHC and co-stimulatory molecules while expression of inhibitory ligands were reduced. RNA-sequencing of both tumor-associated T cells and macrophages revealed significant genomic changes in both subsets that is consistent with ACY241-mediated enhancement of immune priming. These broad immunomodulatory properties of ACY241 were associated with significantly enhanced tumor-associated T cell effector functionality, robust anti-tumor response, and significantly prolonged survival of NSCLC-bearing mice when combined with the chemotherapy drug Oxaliplatin. ConclusionCollectively, our studies highlight the broad immunomodulatory effect of ACY241 as a promising HDAC6 inhibitor which coupled with Oxaliplatin promotes robust therapeutic outcomes in a pre-clinical model of NSCLC, providing compelling rationale for the clinical testing of this novel combinatorial regimen in NSCLC.

immunology↗