Background: A deubiquitinating enzyme OTUB1 inhibits Lys-63-linked ubiquitination by binding to a ubiquitin-conjugating enzyme UBC13. Results: A mechanism of human OTUB1-UBC13 interaction was revealed by human OTUB1-UBC13-MMS2 complex structure and structure-based mutagenesis. Conclusion:The atomic-level interactions presented by the OTUB1-UBC13-MMS2 complex structure are critical for Lys-63-linked ubiquitination inhibition. Significance: Learning how ubiquitination is regulated by the OTUB1-UBC13 interaction is crucial for understanding DNA damage response in biology.

Trehalose cinnamoyl esters (TCs) were synthesized by esterification of trehlaose with cinnamoyl chloride. Two TCs with different degrees of substitution were synthesized, and trehalose cinnamoyl ester thin film-coated glass plates were prepared by a dip-coating method. Photocuring of the TCs was confirmed by ultraviolet–visible spectral changes. The surface of photo-cured TCs were found smooth as observed in a scanning electron microscope. The cell proliferation on the photo-cured TCs was investigated using 3T3 Swiss Albino mouse embryo fibroblasts. The results of the cell proliferation assay revealed that the photo-cured TCs with higher degrees of substitution promoted the cell proliferation compared with a polystyrene culture plate and the photo-cured TCs with lower degrees of substitution. The contact angle of the photo-cured TCs with higher degrees of substitution was 101.0° ± 1.6°, which is much higher than that of the polystyrene culture plate, and it is out of the range known to be suitable for cell adhesion. Nevertheless, the cell unexpectedly grew best on the photo-cured TCs with higher degrees of substitution. Fibronectin binding assay was carried out using fluorescent probe-modified fibronectin, and more fibronectin was found adsorbed onto photo-cured TCs than a polystyrene culture plate.

High-density β-tricalcium phosphate (β-TCP) ceramics with a small amount of tri-and pentavalent vanadium ions addition (≦1.0 mol%) were successfully prepared by hot pressing. Tri-and pentavalent vanadium ions were substituted for a Ca ion at the Ca(5) site located in β-TCP crystal structure and for a P ion in the PO 4 group, respectively. The sinterability and mechanical properties of β-TCP doped with vanadium ions (V-β-TCPV) were improved with increasing vanadium ion content. The bending and compressive strengths of V-β-TCPVs were comparable to those of the hard tissue of a living body.

Tricalcium phosphate doped with a small amount of both V(III) and V(V) ions (V-β-TCPV) was successfully prepared using a solid-state reaction, and its in vitro cell cytotoxicity was investigated using V79 cells. We found that the V(III) ion was substituted for a Ca ion at the Ca(5) site located in the β-Ca 3 (PO 4) 2 (β-TCP) crystal structure and that the V(V) ion was substituted for a P ion in the PO 4 group of the β-TCP crystal structure. The cell cytotoxicity of the V-β-TCPVs increased gradually with increasing amounts of vanadium ion doping. The β-TCP doped with 1.0 mol% vanadium ions showed low toxicity. V-β-TCPVs doped with a small amount of vanadium ions are expected to be significant new implant biomaterials.

Manganese (II) ions were substituted for Ca 2+ ions at the Ca(4) and Ca(5) sites located in the A column of the β-tricalcium phosphate (β-TCP) crystal structure, and effects of additions of Mn 2+ ions on proliferation and differentiation of osteoblasts were examined using mouse MC3T3-E1 osteoblast-like cells. The X-ray diffraction patterns of β-TCP doped with manganese (II) ions (Mn-β-TCP) indicated the formation of β-TCP solid solution to 13.64 mol%. MC3T3-E1 cells attached on Mn-β-TCP well proliferated compare to those on β-TCP. In particular, Mn-β-TCP doped with 3 mol% showed the most excellent cell proliferation and the highest ALP activity level. We consider that the new bone formation may be promoted by dissolution of calcium ions and manganese ions from Mn--TCP. The present Mn-β-TCP is expected as an implant biomaterial with enhanced bioactivity.