Biology subjects

Yoshinaga, N.

Publications and source records attributed to Yoshinaga, N..

4 recordsLinked to original sources

bioRxiv2022

Collective gradient sensing by swimming bacteria without clustering

We characterize the taxis enhancement of swimming bacteria by collective migration without apparent clustering. We confine dilute Salmonella suspension in a shallow channel and evaluate the thermotaxis response to local heating and diffusion. By combining cell tracking analysis and numerical simulation based on simple modeling, we show that the alignment interaction suppresses orientation fluctuation, strengthens migration bias, and also prevents the dispersion of accumulated population. The results show a prominent example of how a collective motion of active matter implements a biological function.

biophysics↗

bioRxiv2022

Tethering designer short double-stranded RNA to mRNA for co-delivery of molecularly-targeted adjuvants and antigens towards cancer vaccination

Integrating antigen-encoding mRNA and immunostimulatory adjuvant into a single formulation is a promising approach to potentiating the efficacy of mRNA vaccines. Here, we developed a scheme based on RNA engineering to integrate adjuvancy directly into antigen-encoding mRNA strands without hampering the ability to express antigen proteins. Short double-stranded RNA (dsRNA) was designed to target retinoic acid-inducible gene-I (RIG-I), an innate immune receptor, for effective cancer vaccination and then tethered onto mRNA strand via hybridization. Tuning the dsRNA structure and microenvironment by changing its length and sequence enabled the determination of the structure of dsRNA-tethered mRNA efficiently stimulating RIG-I. Eventually, the formulation loaded with dsRNA-tethered mRNA of the optimal structure effectively activated mouse and human dendritic cells and drove them to secrete a broad spectrum of proinflammatory cytokines without increasing the secretion of anti-inflammatory cytokines. Notably, the immunostimulating intensity was tunable by modulating the number of dsRNA along mRNA strand, which prevents excessive immunostimulation. Versatility in the applicable formulation is a practical advantage of the dsRNA-tethered mRNA. Its formulation with three existing systems, i.e., anionic lipoplex, ionizable lipid-based lipid nanoparticles, and polyplex micelles, induced appreciable cellular immunity in the mice model. Of particular interest, dsRNA-tethered mRNA encoding ovalbumin (OVA) formulated in anionic lipoplex used in clinical trials exerted a significant therapeutic effect in the mouse lymphoma (E.G7-OVA) model. In conclusion, the system developed here provides a simple and robust platform to supply the desired intensity of immunostimulation in various formulations of mRNA cancer vaccines.

bioengineering↗

bioRxiv2022

Mode selection mechanism in traveling and standing waves revealed by Min wave reconstituted in artificial cells

Reaction-diffusion coupling (RDc) generates spatiotemporal patterns, including two dynamic wave modes: traveling and standing waves. Although mode selection plays a significant role in the spatiotemporal organization of living cell molecules, the mechanism for selecting each wave mode remains elusive. Here, we investigated a wave mode selection mechanism using Min waves reconstituted in artificial cells, emerged by the RDc of MinD and MinE. Our experiments and theoretical analysis revealed that the balance of membrane binding and dissociation from the membrane of MinD determines the mode selection of the Min wave. We successfully demonstrated that the transition of the wave modes can be regulated by controlling this balance and found hysteresis characteristics in the wave mode transition. These findings highlight a novel role of the balance between activators and inhibitors as a determinant of the mode selection of waves by RDc and depict a novel mechanism in intracellular spatiotemporal pattern formations. TeaserActivator-inhibitor balance determines whether a nonlinear wave in live cells becomes a traveling wave or standing wave.

biophysics↗

bioRxiv2019

Cell-sized confinement controls generation and stability of a protein wave for spatiotemporal regulation in cells

Min system, which determines the cell division plane of bacteria, uses the localization change of protein (Min wave) emerged by a reaction-diffusion coupling. Although previous studies have shown that cell-sized space and boundaries modulate shape and speed of Min waves, its effects on Min wave emergence was still elusive. Here, by using a fully confined microsized space as a mimic of live cells, we revealed that confinement changes conditions for Min wave emergence. In the microsized space, an increase of surface-to-volume ratio changed the localization efficiency of proteins on membranes, and therefore, suppression of the localization change was necessary to produce stable Min wave generations. Furthermore, we showed that the cell-sized space more strictly limits parameters for wave emergence because confinement inhibits instability and excitability of the system. These results illuminate that confinement of reaction-diffusion systems works as a controller of spatiotemporal patterns in live cells.

biophysics↗