A tetravalent peptide that binds to the RANK-binding region of TRAF6 via a multivalent interaction efficiently inhibits osteoclast differentiation.

Inhibition of osteoclast differentiation is a promising approach for the treatment of osteoporosis and rheumatoid arthritis. Receptor activator of nuclear factor kappa B (NF-κB) (RANK), which is an essential molecule for osteoclast differentiation, interacts with tumor necrosis factor (TNF) receptor-associated factor 6 (TRAF6) to transduce downstream signals. Both RANK and TRAF6 have homo-trimeric structures, forming a multivalent interaction between the Pro-X-Glu-X-X-(aromatic/acidic) motif of RANK and the C-terminal domain of TRAF6 (TRAF-C), that markedly increases the binding affinity. Here, we designed a tetravalent peptide, RANK-tet, containing the TRAF-C-binding motif of RANK and found that RANK-tet binds to TRAF-C with high affinity. In contrast, a monomeric form of RANK-tet (RANK-mono) with the same TRAF-C-binding motif did not bind to TRAF-C, clearly indicating the multivalent interaction is strictly required for the high-affinity binding to TRAF-C. RANK-tet did not bind to a series of TRAF-C-mutants with an amino acid substitution in the RANK-binding region, indicating that RANK-tet specifically targets the RANK-binding region of TRAF-C. A cell-permeable form of RANK-tet that has poly-Arg residues at each C-terminal of the TRAF-C-binding motif efficiently inhibited the RANK ligand (RANKL)-induced differentiation of bone marrow cells to osteoclasts. Thus, this compound can be an effective anti-osteoclastogenic agent.

Disruption of entire Cables2 locus leads to embryonic lethality by diminished Rps21 gene expression and enhanced p53 pathway.

In vivo function of CDK5 and Abl enzyme substrate 2 (Cables2), belonging to the Cables protein family, is unknown. Here, we found that targeted disruption of the entire Cables2 locus (Cables2d) caused growth retardation and enhanced apoptosis at the gastrulation stage and then induced embryonic lethality in mice. Comparative transcriptome analysis revealed disruption of Cables2, 50% down-regulation of Rps21 abutting on the Cables2 locus, and up-regulation of p53-target genes in Cables2d gastrulas. We further revealed the lethality phenotype in Rps21-deleted mice and unexpectedly, the exon 1-deleted Cables2 mice survived. Interestingly, chimeric mice derived from Cables2d ESCs carrying exogenous Cables2 and tetraploid wild-type embryo overcame gastrulation. These results suggest that the diminished expression of Rps21 and the completed lack of Cables2 expression are intricately involved in the embryonic lethality via the p53 pathway. This study sheds light on the importance of Cables2 locus in mouse embryonic development.

Reversible Color and Shape Changes of Nanostructured Fibers of a Macrocyclic π-Extended Thiophene Hexamer Promoted by Adsorption and Desorption of Organic Vapor.

A phenyl-substituted macrocyclic π-extended thiophene hexamer 1, composed of four thienylene-ethynylene and two thienylene-vinylene units, has a solid-state structure in which π-π, CH-π, and van der Waals interactions occur. Slow addition of acetone to a solution of 1 in CS2 produces a yellow nanostructured fiber 1-A containing a 1:1.5:1 ratio of 1, acetone, and CS2. Over a 2 min period at 25 °C, 1-A gradually changes to an orange fiber 1-B containing a 1:0.5:1 ratio of 1, acetone, and CS2. On exposure to acetone vapor, 1-B regenerates 1-A (vapochromism), and removal of all solvents from 1-A and 1-B generates a red-orange fiber 1-C, which upon brief immersion in acetone/CS2 produces 1-A. Furthermore, 1-C is converted to orange yellow fiber 1-D upon exposure to acetone vapor for 1 s at 25 °C. Analysis of the horizontal and vertical profiles of the X-ray diffraction (XRD) patterns shows that removal of solvent from 1-A reversibly creates 1-B in conjunction with a shape and size change along with arching.

H1foo Has a Pivotal Role in Qualifying Induced Pluripotent Stem Cells.

Embryonic stem cells (ESCs) are a hallmark of ideal pluripotent stem cells. Epigenetic reprogramming of induced pluripotent stem cells (iPSCs) has not been fully accomplished. iPSC generation is similar to somatic cell nuclear transfer (SCNT) in oocytes, and this procedure can be used to generate ESCs (SCNT-ESCs), which suggests the contribution of oocyte-specific constituents. Here, we show that the mammalian oocyte-specific linker histone H1foo has beneficial effects on iPSC generation. Induction of H1foo with Oct4, Sox2, and Klf4 significantly enhanced the efficiency of iPSC generation. H1foo promoted in vitro differentiation characteristics with low heterogeneity in iPSCs. H1foo enhanced the generation of germline-competent chimeric mice from iPSCs in a manner similar to that for ESCs. These findings indicate that H1foo contributes to the generation of higher-quality iPSCs.

Bio-active polymer implants to adipose tissue as in situ source of reprogramming cells.

The implants from natural polymer chitosan was developed by sorption of non-viral DNA vector. These assemblies were shown to be biocompatible and able to transfect the surrounding cells with reprogramming factors. Transgenic rats from the strain allowing visualization of Nanog-positive stem cells received these implants into their adipose deposits. After 8 days we were able to detect in situ-transfected cells. Transfected cells were positive for YFP fluorescence and transiently expressed the markers correlating with stemness.