Biology subjects

Julian, L. M.

Publications and source records attributed to Julian, L. M..

3 recordsLinked to original sources

bioRxiv2025

A bioprinting approach for high-throughput production of micropatterned neuroepithelial tissues and modeling TSC2-deficient brain malformations

In vitro human pluripotent stem cell-derived models have been crucial in advancing our understanding of the mechanisms underlying neurodevelopment, though knowledge of the earliest stages of brain formation is lacking. Micropatterning of cell populations as they transition from pluripotency through the process of neurulation can produce self-assembled neuroepithelial tissues (NETs) with precise spatio-temporal control, enhancing the fidelity of hPSC models to the early developing human brain and their use in phenotypic assessments. Here, we introduce an accessible, customizable and scalable method to produce self-assembled NETs using bioprinting to rapidly deposit reproducibly sized extracellular matrix droplets. Matrix addition to the media provides a scaffold that promotes 3D tissue folding, reflecting neural tube development. We demonstrate that these scaffolded NETs (scNETs) exhibit key architectural and biological features of the human brain during normal and abnormal development, notably hyperproliferation and structural malformations induced by TSC2-deficiency, and provide a robust drug screening tool.

neuroscience↗

bioRxiv2021

Three-dimensional drug screen identifies HDAC inhibitors as therapeutic agents in mTORC1-driven lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is a rare disease involving cystic lung destruction by invasive LAM cells. These cells harbor loss-of-function mutations in TSC2, conferring constitutive mTORC1 signaling. Rapamycin is the only clinically approved disease-modifying treatment, but its action is cytostatic and disease progresses upon its withdrawal. There is a critical need to identify novel agents that prevent the invasive phenotype and/or eradicate the neoplastic LAM cells. Here, we employed novel cellular and extracellular models to screen for candidate therapeutics in a physiologically relevant setting. We observed that lung-mimetic hydrogel culture of pluripotent stem cell-derived diseased cells more faithfully recapitulates human LAM biology compared to conventional culture on two-dimensional tissue culture plastic. Leveraging our culture system, we conducted a three-dimensional drug screen using a custom 800-compound library, tracking cytotoxicity and invasion modulation phenotypes at the single cell level. We identified histone deacetylase (HDAC) inhibitors as a group of anti-invasive agents that are also selectively cytotoxic towards TSC2-/- cells. Unexpectedly, we observed that next generation ATP-competitive mTORC1/2 inhibitors potentiate invasion. We determined anti-invasive effects of HDAC inhibitors to be independent of genotype, while selective cell death is mTORC1-dependent and mediated by apoptosis. Drug performance was subsequently evaluated at the single cell level in zebrafish xenografts. We observed consistent therapeutic efficacy in vivo at equivalent concentrations to those used in vitro, substantiating HDAC inhibitors as potential therapeutic candidates for pursuit in patients with LAM. One Sentence SummaryWe performed a drug screen in 3D and discovered HDAC inhibitors exhibit therapeutic efficacy in models of the lung disease lymphangioleiomyomatosis.

cell biology↗

bioRxiv2019

TSC2-deficiency potentiates a catabolic signaling switch that differentiates neural and neural crest lineage development and progressive disease manifestations

Lymphangioleiomyomatosis (LAM) is a rare lung disease marked by cystic destruction caused by invasive LAM cells harboring loss-of-function mutations in TSC2 that exhibit dysregulated mTORC1 signaling. Rapamycin, the only approved treatment, is not curative. Therapeutic discovery has been limited by inadequate cell and animal models due to the unknown LAM cell of origin. We report a novel TSC2--/-- human pluripotent stem cell (hPSC)-derived neural crest cell (NCC) model, which replicates key LAM features. Leveraging this model, temporal RNA sequencing and genome-wide CRISPR knockout screens identified synthetic lethal genes including TWIST1 and SUN4. Antisense oligonucleotides (ASOs) targeting TWIST1 and SUN4 demonstrated selective TSC2 mutant NCC cytotoxicity and inhibited invasion. Using a "test-withdraw-monitor" clinical trial paradigm, TWIST1 and SUN4 ASOs profoundly suppressed tumor viability in a Tsc2--/-- mouse allograft model and eradicated 40% of tumors, outperforming standard of care rapamycin and highlighting their promise as novel cytoablative LAM therapeutics.

cancer biology↗