Takashi Sakai

Kupffer cells (KCs) are resident macrophages in the liver. Recent studies have revealed that KCs are closely related to inflammatory liver diseases, including nonalcoholic liver diseases (NAFLD). From this point of view, KC transplantation can be a candidate for immunotherapy against inflammatory diseases. Similar to general macrophages, KCs show several different phenotypes according to their environment. Activated KCs are involved in either proinflammatory responses or anti-inflammatory responses. Thus, to manipulate KCs for immunotherapy, it is crucial to control the direction of KC activation. Here, we summarize the outlook and the issues hindering immunotherapy using KC transplantation.

Protein crystallization is usually conducted by using precipitants, although the “salting-out” phenomenon is still unclear and complex. Moreover, the addition of precipitants sometimes results in irreversible disordered precipitation of protein molecules. Although precipitant-free lysozyme crystals obtained by centrifugal concentration showed significant changes in three-dimensional structure compared to the structure of salted-out crystals, it was rather difficult to mount crystals from a viscous dense liquid phase after centrifugal concentration, and the quality of the crystals often deteriorated during the mounting process. Here we present novel precipitant-free crystallization methods, which were effective for lysozyme and glucose isomerase. Tetragonal lysozyme crystals were successfully crystallized in a glass capillary simply by drying highly concentrated lysozyme solution in the presence of 0.01 M hydrochloric acid without using any precipitants. Glucose isomerase dissolved in ultra-pure water was also successfully crystallized in hanging drops by drying highly concentrated solution under low-humidity conditions. Oscillation images of the obtained crystals were safely collected without handling; they clearly indicated the crystals had a tetragonal form for lysozyme and an orthorhombic form for glucose isomerase, and their lattice parameters are similar to those of previously reported crystals obtained by salting-out methods.

We simulated the granular packings filled in slowly tilt box, and understand the destabilization process of the packings by observation of the process more detail than in the previous experiments. The reliability of the simulation was confirmed by reproducing some of the results of the experiments such as rearrangements of the particles at the surface layer. Most of previous works evaluate the stability of the packings by mobilization of friction force at the particle contacts. But in our simulation, the mobilization of friction force of the upper side particles hardly change when the tilt angle increases. We found that the relationship of the mobilization of friction force and global stability is little. But the direction of contacts change when slope angle increase. We found that the change in the contact direction characterize the instability of the packings rather than the mobilization of friction force.

Nucling is an Apaf1‐binding proapoptotic protein involved in apoptosome‐mediated apoptosis. Luciferase assays have revealed that the activation of nuclear factor‐κB induced by tumor necrosis factor‐α, interleukin‐1β and lipopolysaccharide is downregulated by the overexpression of Nucling in HEK293 cells. Moreover, the expression of endogenous cyclooxygenase 2, tumor necrosis factor‐α and galectin‐3, the end‐point molecules in the pathway for the activation of nuclear factor‐κB, as well as nuclear factor‐κB (p65) itself, is upregulated in Nucling gene‐deficient mouse embryonic fibroblasts, suggesting that nuclear factor‐κB is a target of Nucling. Subsequent study has revealed that Nucling physically interacts with nuclear factor‐κB (p65 and p50) and that the binding domain of Nucling is its amino‐terminal region (amino acids 1–466) containing ankyrin repeats. Overexpression of Nucling prevents the translocation of nuclear factor‐κB into the nucleus. In addition, the cytoplasmic retention of endogenous nuclear factor‐κB in resting cells is not observed in Nucling gene‐deficient mouse embryonic fibroblasts. These results reveal a novel function of Nucling as a suppressor of nuclear factor‐κB, mediated by its cytoplasmic retention through physical interaction.