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Biology subjects

Galic, M.

Publications and source records attributed to Galic, M..

3 recordsLinked to original sources

Intercellular adhesion boots collective cell migration through elevated membrane tension

In multicellular systems, the migration pattern of individual cells critically relies on the interactions with neighboring cells. Depending on the strength of these interactions, cells either move as a collective, as observed during morphogenesis and wound healing, or migrate individually, as it is the case for immune cells and fibroblasts. Transducers of cell-cell adhesions, such as cadherins coordinate collective dynamics by linking the cytoskeleton of neighboring cells. However, whether intercellular binding alone triggers signals that originate from within the plasma membrane itself, remains unclear. To address this question, we designed photoswitchable cell-cell adhesions that selectively connect adjacent plasma membranes without linking directly to cytoskeletal elements. We find that these intercellular adhesions are sufficient to achieve collective cell migration. Here, linking adjacent cells increases membrane tension, which activates the enzyme phospholipase D2. The resulting increase in phosphatidic acid, in turn, stimulates the mammalian target of rapamycin, a known actuator of collective cell migration. Collectively, these findings introduce a membrane-based signaling axis as promotor of collective cell dynamics, which is independent of the direct coupling of cell-cell adhesions to the cytoskeleton.

cell biology↗

Mechanical Strain Activates Planar Cell Polarity Signaling to Coordinate Vascular Cell Dynamics

Mechanical stimuli, particularly laminar blood flow, play a crucial role in shaping the vascular system. Changes in the rate of blood flow manifest in altered shear stress, which activates signaling cascades that drive vascular remodeling. Consistently, dysregulation of the endothelial response to fluid shear forces and aberrant flow patterns both lead to pathological conditions, including impaired blood vessel development and atherosclerosis. Despite its importance, the mechanisms driving the coordinated cell behavior underlying vascular remodeling are not fully understood. Combining classical cell biological approaches with advanced image analysis, mathematical modeling, biomimetic strategies, and in vivo studies, we identify the planar cell polarity (PCP) protein Vangl1 as an enforcer of flow-dependent cell dynamics in the vascular system. We demonstrate that shear stress triggers the relocation of Vangl1 from an internal reservoir to the plasma membrane at the initiation of cell remodeling. Membrane enrichment of Vangl1 is mediated by a Coronin1C-dependent shift in the equilibrium between endo- and exocytosis and results in the spatial reorganization of another essential PCP protein, Frizzled6 (Fzd6). The resulting mutual exclusion of the core PCP proteins Fzd6 and Vangl1 augments differential junctional and cytoskeletal dynamics along the flow axis. Loss of Vangl1 limits the ability of endothelial cells to respond to shear forces in a coordinated fashion, resulting in irregular cell alignment along the flow direction and erroneous vessel sprouting. Together, these studies introduce core PCP signaling as a determinant of collective cell dynamics and organization of the vascular system.

cell biology↗

Primary Human Neutrophils and Monocytes/Macrophages Migrate along Endothelial Cell Boundaries to Optimize Search Efficiency

Neutrophils and monocytes/macrophages are sentinels of inflammatory signals. To reach the sites of action, both cell types attach to and then transmigrate the endothelial cell layer that lines the luminal side of blood vessels. While it has been reported that neutrophils and monocytes/macrophages actively migrate along the surface of the vasculature, it remains elusive if and how these motion pattern augment the efficiency of the immune system. Here, we conducted co-culture experiments of primary human monocytes and neutrophils, respectively, with human umbilical vein endothelial cells (HUVECs). Combining classical biomedical approaches with quantitative image analysis and numerical models, we find that immune cells simultaneously increase the number of sampled cells vs. traveled distance and sensitivity to chemokines by migrating along endothelial cell-cell boundaries. Collectively, these findings establish search optimization of neutrophils and monocytes/macrophages through limitation of motion pattern to cell-cell boundaries.

cell biology↗