The adherens junction (AJ) is a major cell-cell junction that mediates cell recognition, adhesion, morphogenesis, contractile function and tissue integrity. Although AJs transmit forces generated by actomyosin from one cell to another, AJs have long been considered as a site where signal transduction from cadherin ligation takes place through cell adhesion as seen with other conventional membrane receptors. Recent studies are unraveling the existence of mechanotransduction at AJs and its possible molecular mechanism in which α-catenin in the cadherin-catenin complex changes its conformation in a force-dependent manner. This mechanotransduction has advantages in that it can transmit more precise temporal, quantitative, and spatial information than signaling using diffusion of second messengers or phosphorylation cascades.
Using atomic force microscopy technique, it is capable of picking up a single protein molecule to apply a mechanical force. This technique, called “force spectroscopy”, provides unique information about the intermediates and the free energy landscape of the mechanical unfolding of proteins. In this review we introduce recent studies that answer some fundamental questions: “Is the mechanical resistance of protein isotropic?”, “What is the structure of the transition state in the mechanical unfolding like?” and “Is the mechanical unfolding related to biological functions?”.
Mitochondria, dynamic organelles that undergo continuous cycles of fusion and fission events, are believed to play an important role in controlling organelle morphology, copy number, mitochondrial DNA maintenance and are also involved in cellular innate antiviral immunity. In mammals, mitochondrial dynamics rely on high molecular weight GTPases, mitofusin (Mfn1 and Mfn2), OPA1, and Drp1. Recently our studies revealed that Mfn2, a mediator of mitochondrial fusion, acts as an inhibitor of mitochondria-mediated antiviral immunity, which leads us to a linkage between mitochondrial dynamics and antiviral immunity in mammals. In this review, we discuss the participation of mitochondrial dynamics in antiviral immune responses and also show the evidence that the physiological function of mitochondria plays a key role in innate antiviral immunity.
The origin of information processing is a fundamental problem in evolutionary biology. True slime mold, Physarum, has become a model organism for study of problem solving by single-celled organisms. Here we report its ability to find a smart network by describing its aptitude in maze solving, multi purpose optimization for transportation network and risk management in a spatio-temporally varying field. We discuss these results in the context of a risk management strategy.
In the post-genome era, with the availability of high-throughput data, our biological focus makes a shift from a behavior of individual components to their regulatory/causative/interactive relationships. Gene network, which is inferred from microarray data by using reverse engineering algorithms, gives valuable information about the regulation of genes in the living cells under the certain conditions. In particular, this technology is applied to the biomedical research fields, e.g. identification of drug targets and prognosis markers. In this short review, we summarize what gene network is and how it is inferred. We also show our work that identified new drug target of well-known compound in human endothelial cells by gene network analysis.