Biology subjects

Tkach, J. M.

Publications and source records attributed to Tkach, J. M..

3 recordsLinked to original sources

bioRxiv2026

Physiological perfusion of human vasculature reveals a YAP/TAZ-Apelin switch linking intraluminal flow to endothelial state transitions and vessel remodeling

Vascular flow delivers nutrients and imposes hemodynamic forces that govern vessel behavior in health and disease, yet fully human systems that recapitulate and tune physiological intraluminal flow in three-dimensional (3D) tissues are lacking. We developed VIVOS (Vascularized In Vitro Organ Systems), a platform that couples perfused human vascular beds to tunable pumps, generating continuous intraluminal flow through millimetre-scale vessels and 3D tissues at physiological shear stresses and pressures. VIVOS supports integration and perfusion of diverse human organoids and tissues, including lung organoids, cerebral organoids, vascular organoids, breast spheroids, and human retinal explants, as well as enables direct measurement and control of pressure, shear stress, and perfusion-dominant compound transport over extended culture periods. By tuning intraluminal flow and applying single-cell transcriptomics, we uncover a remodeling program in which laminar shear stress acts through a YAP/TAZ-TEAD "switch" to rewire an Apelin ligand-receptor axis and bias tip-stalk endothelial states, reshaping human vascular networks and linking hemodynamic cues to cell state transitions. We further model fast-flow arteriovenous malformations (AVMs) from Hereditary Hemorrhagic Telangiectasia and show that BMP9 constrains vessel caliber and perfusion while antagonizing a VEGF-driven angiogenic program, generating flow-quantified AVM-like lesions in a fully human 3D context. Together, these findings establish VIVOS as a generalizable platform that links physiological intraluminal flow to endothelial state transitions and vessel remodeling, enabling preclinical testing and mechanistic dissection of flow-regulated vascular pathologies in perfused 3D human tissues under defined hemodynamic conditions.

bioengineering↗

bioRxiv2023

qTAG: An adaptable CRISPR-based endogenous tagging protocol using optimized repair cassettes

Endogenous tagging makes it possible to study a proteins localization, dynamics, and function within its native regulatory context. This is typically accomplished via CRISPR, which involves inserting a sequence encoding a functional tag into the reading frame of a gene. However, this process is often inefficient. Here, we introduce the "quickTAG," or qTAG system, a versatile collection of optimized repair cassettes designed to make CRISPR-mediated tagging more accessible. By including a desired tag sequence linked to a selectable marker in the cassette, integrations can be quickly isolated post-editing. The core sequence scaffold within these constructs incorporates several key features that enhance flexibility and ease of use, such as: specific cassette designs for N- and C-terminus tagging; standardized cloning sequences to simplify the incorporation of homology arms for HDR or MMEJ-based repairs; restriction sites next to each genetic element within the cassette for easy modification of tags and selectable markers; and the inclusion of lox sites flanking the selectable marker to allow for marker gene removal following integration. We showcase the versatility of these cassettes with a diverse range of tags, demonstrating their applications in fluorescence imaging, proximity-dependent biotinylation, epitope tagging, and targeted protein degradation. The adaptability of this scaffold is also exhibited by incorporating novel tags such as mStayGold, which offer enhanced brightness and photostability, reconciling prolonged live-cell imaging of proteins at their endogenous levels. Finally, by leveraging the restriction sites, entirely distinct cassette structures and editing schemes were developed. These enabled scenarios that included conditional expression tagging, selectable knockout tagging, and safe-harbor expression. Our existing and forthcoming collection of plasmids will be accessible through Addgene. It includes ready-to-use constructs targeting common subcellular marker genes, as well as an assortment of tagging cassettes for the tagging of genes of interest. The qTAG system offers an accessible framework to streamline endogenous tagging and will serve as an open resource for researchers to adapt and tailor for their own experiments.

molecular biology↗

bioRxiv2021

Global cellular response to chemical perturbation of PLK4 activity and abnormal centrosome number

Centrosomes act as the main microtubule organizing centre (MTOC) in metazoans. Centrosome number is tightly regulated by limiting centriole duplication to a single round per cell cycle. This control is achieved by multiple mechanisms, including the regulation of the protein kinase PLK4, the most upstream facilitator of centriole duplication. Altered centrosome numbers in mouse and human cells cause p53-dependent growth arrest through poorly defined mechanisms. Recent work has shown that the E3 ligase TRIM37 is required for cell cycle arrest in acentrosomal cells. To gain additional insights into this process, we undertook a series of genome-wide CRISPR/Cas9 screens to identify factors important for growth arrest triggered by treatment with centrinone B, a selective PLK4 inhibitor. We found that TRIM37 is a key mediator of growth arrest after partial or full PLK4 inhibition. Interestingly, PLK4 cellular mobility decreased in a dose-dependent manner after centrinone B treatment. In contrast to recent work, we found that growth arrest after PLK4 inhibition correlated better with PLK4 activity than with mitotic length or centrosome number. These data provide insights into the global response to changes in centrosome number and PLK4 activity and extend the role for TRIM37 in regulating the abundance, localization and function of centrosome proteins.

cell biology↗