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Poon, Y.

Publications and source records attributed to Poon, Y..

3 recordsLinked to original sources

A Generative Virtual Tissue Model Enables Computational Design of Therapeutic Perturbation Strategies

Computational design has transformed many fields of engineering, where simulators can explore millions of candidate design configurations before experimental development and testing. Therapeutic design in biomedicine has resisted computational design approaches because disease progression and therapeutic response emerge from interactions among many cell types within human tissue, governed by biochemical parameters that are largely unknown and potentially unknowable. Here, we introduce the Cell Interaction Foundation Model (CIFM), a virtual tissue model that forward-simulates the transcriptional dynamics of cells in human tissue under arbitrary therapeutic conditions based upon a spatial transcriptomic seed. CIFM is a geometric graph neural network trained by self-supervised masked-transcriptome prediction on millions of cellular microenvironments spanning human tissue types and disease states; generative, auto-regressive, monte-carlo play-out, then, simulates transcriptional dynamics under combinatorial perturbations from a spatial transcriptomic seed. We validate CIFM by showing accuracy gains in gene expression prediction and imputation, disease classification, recapitulation of perturbation responses in prostate cancer models, and recovery of T cell-tumor signaling measured in cell-cell sequencing experiments. Beyond such conventional tasks, CIFM enables target identification and therapeutic design through generative tissue simulation play-outs. Analyzing over 106 single and combinatorial perturbations, CIFM designs immunotherapy strategies for cancer and autoimmune disease that exploit combinatorial manipulation of signaling pathways to induce or suppress immune activation. Broadly, CIFM shows how generative artificial intelligence methods can be applied to model emergent behavior in highly interacting biological systems, yielding new approaches to fundamental understanding of tissue behavior as well as large-scale therapeutic design.

bioinformatics↗

Short RNA chaperones promote aggregation-resistant TDP-43 conformers to mitigate neurodegeneration

Aberrant aggregation of the prion-like, RNA-binding protein TDP-43 underlies several debilitating neurodegenerative proteinopathies, including amyotrophic lateral sclerosis (ALS). Here, we define how short, specific RNAs antagonize TDP-43 aggregation. Short, specific RNAs engage and stabilize the TDP-43 RNA-recognition motifs, which allosterically destabilizes a conserved helical region in the prion-like domain, thereby promoting aggregation-resistant conformers. By mining sequence space, we uncover short RNAs with enhanced activity against TDP-43 and diverse disease-linked variants. The solubilizing activity of enhanced short RNA chaperones corrects aberrant TDP-43 phenotypes in optogenetic models and ALS patient-derived neurons. Remarkably, an enhanced short RNA chaperone mitigates TDP-43 proteinopathy and neurodegeneration in mice. Our studies reveal mechanisms of short RNA chaperones and pave the way for the development of short RNA therapeutics for fatal TDP-43 proteinopathies.

biochemistry↗

Inhibitory effect of lactobacilli supernatants on biofilm and filamentation of C. albicans, C. tropicalis, and C. parapsilosis

Probiotic Lactobacillus strains had been investigated for the potential to protect against infection caused by the major fungal pathogen of human, Candida albicans. Besides antifungal activity, lactobacilli demonstrated a promising inhibitory effect on biofilm formation and filamentation of C. albicans. On the other hand, two commonly isolated non-albicans Candida species, C. tropicalis and C. parapsilosis, have similar characteristics in filamentation and biofilm formation with C. albicans. However, there is scant information of the effect of lactobacilli on the two species. In this study, biofilm inhibitory effects of L. rhamnosus ATCC 53103, L. plantarum ATCC 8014, and L. acidophilus ATCC 4356 were tested on the reference strain C. albicans SC5314 and six bloodstream isolated clinical strains, two each of C. albicans, C. tropicalis, and C. parapsilosis. Cell-free culture supernatants (CFSs) of L. rhamnosus and L. plantarum significantly inhibited in vitro biofilm growth of C. albicans and C. tropicalis. L. acidophilus, conversely, had little effect on C. albicans and C. tropicalis but was more effective on inhibiting C. parapsilosis biofilms. Neutralized L. rhamnosus CFS at pH 7 retained the inhibitory effect, suggesting that exometabolites other than lactic acid produced by the Lactobacillus strain might be accounted for the effect. Furthermore, we evaluated the inhibitory effects of L. rhamnosus and L. plantarum CFSs on the filamentation of C. albicans and C. tropicalis strains. Significantly less Candida filaments were observed after co-incubating with CFSs under hyphae-inducing conditions. Expressions of six biofilm-related genes (ALS1, ALS3, BCR1, EFG1, TEC1, and UME6 in C. albicans and corresponding orthologs in C. tropicalis) in biofilms co-incubated with CFSs were analyzed using quantitative real-time PCR. When compared to untreated control, the expressions of ALS1, ALS3, EFG1, and TEC1 genes were downregulated in C. albicans biofilm. In C. tropicalis biofilms, ALS3 and UME6 were downregulated while TEC1 was upregulated. Taken together, the L. rhamnosus and L. plantarum strains demonstrated an inhibitory effect, which is likely mediated by the metabolites secreted into culture medium, on filamentation and biofilm formation of C. albicans and C. tropicalis. Our finding suggested an alternative to antifungals for controlling Candida biofilm.

microbiology↗