Prominin-1 Modulates Rho/ROCK-Mediated Membrane Morphology and Calcium-Dependent Intracellular Chloride Flux

Membrane morphology is an important structural determinant as it reflects cellular functions. The pentaspan membrane protein Prominin-1 (Prom1/CD133) is known to be localised to protrusions and plays a pivotal role in migration and the determination of cellular morphology; however, the underlying mechanism of its action have been elusive. Here, we performed molecular characterisation of Prom1, focussing primarily on its effects on cell morphology. Overexpression of Prom1 in RPE-1 cells triggers multiple, long, cholesterol-enriched fibres, independently of actin and microtubule polymerisation. A five amino acid stretch located at the carboxyl cytosolic region is essential for fibre formation. The small GTPase Rho and its downstream Rho-associated coiled-coil-containing protein kinase (ROCK) are also essential for this process, and active Rho colocalises with Prom1 at the site of initialisation of fibre formation. In mouse embryonic fibroblast (MEF) cells we show that Prom1 is required for chloride ion efflux induced by calcium ion uptake, and demonstrate that fibre formation is closely associated with chloride efflux activity. Collectively, these findings suggest that Prom1 affects cell morphology and contributes to chloride conductance

Single living cell processing in water medium using focused femtosecond laser-induced shockwave and cavitation bubble

edition: 3status: publishe

Cooperative Optical Trapping of Polystyrene Microparticle and Protein Forming a Submillimeter Linear Assembly of Microparticle

Optical trapping of dielectric and metal particles yields different types of “optically evolving assembly” at air/solution and glass/solution interfaces. However, all these structures have in common that the trapping laser is scattered and propagated through the assembly, expanding from the focus up to a few tens of micrometers. In the present work, we fabricate a single submillimeter linear assembly of polystyrene microparticles starting from the surface of a concentrated lysozyme D2O solution. Such assembly has a three-dimensional linear structure composed of a single microparticle aggregate without folding and bending. Indeed, it is prepared along the lysozyme assembly, which is also generated by optical trapping. The cooperative trapping of the microparticle and lysozyme did not arrange as a homogeneously distributed assembly. Instead, a unique anomalously long assembly of microparticles and a densely, widely, and deeply expanded lysozyme layer were simultaneously prepared. Their morphology was reconstructed by shifting the imaging plane immediately after switching off the trapping laser. Independently, the lysozyme assembly was also confirmed by fluorescence imaging and Raman scattering spectroscopy. Thus, we consider that the described cooperative “optically evolved assembling” has a large potential to fabricate hybrid materials with applications in different fields such as colloid science, protein chemistry, and soft matter