Biology subjects

Zieske, K.

Publications and source records attributed to Zieske, K..

6 recordsLinked to original sources

bioRxiv2025

Stimulus-induced mechanical compaction of biological polymer networks via smart hydrogel microstructures

The remodeling of the extracellular matrix by mechanical forces plays a crucial role in organizing cellular microenvironments. To study these mechanical perturbations, various methods have been developed to modify the cellular microenvironment and to apply controlled forces. However, most existing approaches rely either on instruments that cannot be integrated into lab-on-chip systems or on small probes with limited spatiotemporal precision. Here, we present a lab-on-chip system that enables spatially and temporally controlled mechanical perturbations of biological polymer networks. First, we fabricated thermoresponsive hydrogel microstructures within flow chambers and optimized their material composition and photopolymerization parameters. Second, we demonstrated the temporally controlled compression of Matrigel and collagen networks through temperature-stimulated expansion of the hydrogel microstructures. Following compression, Matrigel was plastically deformed, whereas the collagen network relaxed elastically. Finally, we showed that the compression of collagen networks can be spatially modulated by integrating hydrogel structures responsive to light stimuli. By mimicking the dynamic behavior of cells that remodel biological polymer networks, our method provides a versatile platform for future studies on extracellular matrix remodeling and the effects of mechanical forces on cellular microenvironments in both physiological and pathological contexts.

bioengineering↗

bioRxiv2025

Membrane Topography-Driven Movement of Biomolecular Condensates

Biomolecular condensates are assemblies of proteins or nucleic acids that exhibit liquid-like properties and organize intracellular biochemical reactions within many cells. Some condensates require membrane association, and we previously developed an assay to reconstitute biomolecular condensates in the presence of different membrane topographies. However, the effect of membrane topography on the displacement of biomolecular condensates remains incompletely understood. Here, we studied the movement of biomolecular condensates on lipid membrane-clad microstructures in a cell-free assay. We observed upward movements within microgrooves for untethered condensates. Increased membrane attachment reduced the number of upward movements. Further increasing the membrane attachment led to the formation of elongated condensates. We demonstrated a coordinated sideward movement of these elongated condensates. Finally, we found that molecular crowding with Ficoll70 decreased the frequency of upward movements by slowing condensate growth. Our results indicate that membrane topographies, in combination with membrane attachment patterns, regulate passive biomolecular condensate movement.

synthetic biology↗

bioRxiv2025

Lithographic structuring of thermoresponsive hydrogel on a micron scale

Hydrogel microstructures and microchannels are important tools in biophysical bottom-up approaches for studying the interactions between extracellular obstacles or boundaries and cells. In prior studies, several microstructuring techniques, cell sources, and gel types have been employed to mimic static cellular environments. However, the dynamic nature of the extracellular environment, which exerts forces on cells, plays an important role in tissue-level contexts. To date, only few approaches have been implemenmted to mimic these forces of the extracellular environment. Here, we present an approach for generating arrays of hydrogel microstructures, that expand and contract dynamically in response to temperature modulations. To do this, we use a thermoresponsive hydrogel and a custom-built lithographic setup. Through direct lithographic photopatterning of a liquid phase, we fabricate smart hydrogel microstructures at the micrometer scale (10-100 m) with well-defined geometries. These hydrogel microstructures display reversible size changes of over 70% triggered by temperature modulations. Our study represents a step towards mimicking the dynamic properties of biological boundaries and obstacles. The dynamic nature of smart hydrogel microstructures holds the potential to mimic the micron-scale dynamics of extracellular environments. Our results may thus be relevant for the fields of bioengineering and systems level biophysics offering opportunities for manipulating and exploring cellular interactions with dynamic obstacles.

bioengineering↗

bioRxiv2024

Controlled Protein-Membrane Interactions Regulate Self-Organization of Min Protein Patterns

Self-organizing protein patterns play an essential role in life, governing important cellular processes, such as polarization and division. While the field of protein self-organization has reached a point where basic pattern-forming mechanisms can be reconstituted in vitro using purified proteins, understanding how cells can dynamically switch and modulate these patterns, especially when transiently needed, remains an interesting frontier. Here, we demonstrate the efficient regulation of self-organizing protein patterns through modulation of simple biophysical membrane parameters. Our investigation focusses on the impact of membrane affinity changes on Min protein patterns at lipid membranes composed of E. coli lipids or minimal lipid composition and we present three major results. First, we observed the emergence of a diverse array of pattern phenotypes, ranging from waves to snowflake-like structures. Second, we establish the dependency of these patterns on the density of protein-membrane linkers. Finally, we demonstrate the fine-tuning of snow-flake-like patterns by regulating membrane charge through lipid composition. Our results demonstrate the significant influence of membrane linkage as a straightforward biophysical parameter governing protein pattern formation. Our research points towards a simple yet intriguing mechanism by which cells can adeptly tune and switch protein patterns on the mesoscale.

biophysics↗

bioRxiv2024

Lipid membrane topographies are regulators for the spatial distribution of liquid protein condensates

Liquid protein condensates play important roles in orchestrating subcellular organization and in serving as hubs for biochemical reactions. Recent studies have established associations between lipid membranes and proteins capable of forming liquid condensates, and shown that liquid protein condensates can remodel lipid membranes. However, little is known about how the topography of membranes affects liquid condensates. Here, we devised a cell-free system to reconstitute liquid condensates on lipid membranes with microstructured topographies and demonstrated an important role of lipid membranes topography as a biophysical regulator. By employing membrane surfaces designed with microwells, we found that liquid condensates assemble into orderly patterns. Furthermore, we demonstrated that membrane topographies influence the shape of liquid condensates. Finally, we showed that capillary forces, mediated by membrane topographies, led to the directed fusion of liquid condensates. Our results demonstrate that membrane topography is a potent biophysical regulator for the localization and shape of mesoscale liquid protein condensates.

biophysics↗

bioRxiv2019

Optogenetic control of cell morphogenesis on protein micropatterns

Cell morphogenesis is critical for embryonic development, tissue formation, and wound healing. Our ability to manipulate endogenous mechanisms to control cell shape, however, remains limited. Here we combined surface micropatterning of adhesion molecules with optogenetic activation of intracellular signaling pathways to control the nature and morphology of cellular protrusions. We employed geometry-dependent pre-organization of cytoskeletal structures together with acute activation of signaling pathways that control actin assembly to create a tool capable of generating membrane protrusions at defined cellular locations. Further, we find that the size of microfabricated patterns of adhesion molecules influences the molecular mechanism of cell protrusion: larger patterns enable cells to create actin-filled lamellipodia while smaller patterns promote formation of spherical blebs. Optogenetic perturbation of signaling pathways in these cells changes the size of blebs and convert them into lamellipodia. Our results demonstrate how the coordinated manipulation of adhesion geometry and cytoskeletal dynamics can be used to control membrane protrusion and cell morphogenesis.

bioengineering↗