Current & Upcoming

Cells often face the challenge of rapidly assembling large intracellular structures at defined times and locations. Liquid–liquid phase separation has emerged as a key mechanism for such spatiotemporal organization by locally enriching specific molecules. However, certain cellular structures require more than local enrichment: their components must also adopt defined molecular orientations. How such orientational order emerges remains poorly understood. Here, we address this question by using the assembly of highly ordered centrosomal structures as a model system. We found that a core component of these structures not only forms liquid-like condensates, but also acquires liquid crystal-like orientational order within them. I will discuss how these two modes of self-organization may cooperate to drive the rapid assembly of ordered intracellular structures.

During the peri-­implantation phase of murine embryogenesis, the epiblast proliferates rapidly and undergoes epithelialization. At the same time, the preimplantation pluripotent state transforms into a more developmentally advanced, pregastrulation state. While extensive research has elucidated cell-­ extrinsic signals that direct the developmental progression, such as the Fgf/Mek/Erk pathway, the potential interplay of intrinsic cellular cues remains largely unexplored. To address this, we conducted a comprehensive phenotypic screen using an in vitro model of epiblast development. We identified aurora kinase A as a cell-­ intrinsic factor contributing to Erk activation and transcriptional response. Consequently, suppressing aurora kinase A activity delayed exit from naïve pluripotency. Moreover, our results show that upon entry into mitosis, Erk relocates to the cell division machinery. We found that in dividing cells, a fraction of Erk, with yet elusive functions, localizes on the centrosomes, where its phosphorylation depends on polo-­like kinase 1.

Cell adhesion is essential for shaping tissues during animal development, yet how adhesion is tuned to support different morphogenetic movements remains unclear. We used optogenetics in the Drosophila embryo to address this question by enhancing clustering of E-cadherin, a core component of adherens junctions. Increasing E-cadherin clustering enriches E-cadherin at junctions and reduces its mobility, consistent with enhanced adhesion strength. This approach allows targeted manipulation of cellular adhesive properties in vivo and makes it possible to address questions that were previously difficult to test directly. By analyzing animal development while increasing cell adhesion throughout the epithelial tissue, we found that this causes a strong reduction in cell rearrangements during epithelial morphogenesis and disrupts convergent extension of the embryonic axis. To further understand these effects, we adapted a vertex model to include adhesion-dependent friction between cells. The model predicts that stronger adhesion increases resistance to neighbor exchange and thereby limits tissue remodeling. To test this idea, we analyzed different morphogenetic movements in the fly and their dependence on cell adhesion. We found that enhanced E-cadherin clustering strongly slows morphogenetic processes that depend on both cell shape change and cell rearrangement, while movements that rely primarily on apical constriction can still proceed. Together, these findings suggest that E-cadherin clustering is an important regulator of tissue mechanics and that tuning adhesion is critical for morphogenetic events that require dynamic cell-cell rearrangements

Mesenchymal tissues construct the physical architecture of the developing skull through dynamic interactions between cells and extracellular matrix. Our work investigates how extracellular matrix organization and mechanics regulate mesenchymal cell fate decisions during cranial morphogenesis, and how disruption of these processes may contribute to connective tissue pathology. Using embryonic perturbation models, quantitative tissue imaging, and single-cell approaches, we show that altered matrix crosslinking changes the tempo and spatial organization of connective tissue specialization within the developing skull cap. These findings suggest that connective tissue disease may emerge not only from defects in structural molecules themselves, but from altered developmental states that reshape how cells interpret and build their extracellular environments across scales.

Cellular membranes are dynamic chemical systems whose lipid composition is tightly regulated across space and time, yet the mechanisms governing lipid metabolism, transport, and function remain incompletely understood. I will describe our eKorts in synthetic lipid biology to develop chemical and optogenetic approaches for interrogating membrane function in living cells. These include activity-based imaging strategies for visualizing lipid metabolism and transport, photoaKinity lipid probes for mapping lipid interactomes and uncovering hidden biological functions, and optogenetic membrane editing technologies that enable rapid and spatially precise manipulation of membrane lipid composition. By integrating these approaches with proximity labeling, chemoproteomics, and advanced imaging, we are beginning to reveal new mechanisms governing lipid homeostasis, inter-organelle communication, and the spatiotemporal organization of membrane metabolism and transport. More broadly, these studies highlight how engineered chemical tools can provide new insight into the architecture and function of cellular membranes.

Alterations in glycoprotein expression and composition are an undisputed corollary of developmental processes, host-pathogen interactions and cancer formation. Consequently, some of the most important tumor biomarkers are heavily glycosylated. Understanding cellular glycoproteome changes is paramount but hampered by experimental limitations. Protein glycosylation is mediated by the activities of >200 glycosyltransferases mainly located in the secretory pathway. Since these transferases are interdependent through compensation and competition, traditional methods of molecular cell biology fail to fully address the complexity of glycoprotein biosynthesis. Furthermore, workflows in mass spec-glycoproteome analysis are often restricted to isolated cell lines that do not adequately reflect the interactions within tissues or between tumor and microenvironment. Thus, we lack strategies to understand 1) the protein substrate specificities of individual glycosyltransferases and 2) which glycoproteins are made by cells in response to their microenvironment. We also 3) miss chemical probes to investigate and disrupt cancer-relevant glycosylation. Here, I describe our development of chemical “Precision Tools” to dissect cellular glycosylation. We employ bump-and-hole (BH) engineering to render glycosyltransferases receptive to a chemically modified nucleotide-sugar substrate that carries a bioorthogonal tag and is not used by wildtype transferases. Engineering individual transferases allows differential profiling of their protein substrate specificities. We found that establishing cellular BH systems required innovation in the delivery of corresponding nucleotide-sugarsto the secretory pathway. We have also taken initiative in the development of small molecule inhibitors against cancer-relevant glycosylation enzymes. Thus, chemical Precision Tools allow us to profile protein glycosylation as a key player in cancer biology.

TBA