Human stem cells and articular cartilage regeneration.

The regeneration of articular cartilage damaged due to trauma and posttraumatic osteoarthritis is an unmet medical need. Current approaches to regeneration and tissue engineering of articular cartilage include the use of chondrocytes, stem cells, scaffolds and signals, including morphogens and growth factors. Stem cells, as a source of cells for articular cartilage regeneration, are a critical factor for articular cartilage regeneration. This is because articular cartilage tissue has a low cell turnover and does not heal spontaneously. Adult stem cells have been isolated from various tissues, such as bone marrow, adipose, synovial tissue, muscle and periosteum. Signals of the transforming growth factor beta superfamily play critical roles in chondrogenesis. However, adult stem cells derived from various tissues tend to differ in their chondrogenic potential. Pluripotent stem cells have unlimited proliferative capacity compared to adult stem cells. Chondrogenesis from embryonic stem (ES) cells has been studied for more than a decade. However, establishment of ES cells requires embryos and leads to ethical issues for clinical applications. Induced pluripotent stem (iPS) cells are generated by cellular reprogramming of adult cells by transcription factors. Although iPS cells have chondrogenic potential, optimization, generation and differentiation toward articular chondrocytes are currently under intense investigation

前腹側脳室周囲核における性差発現タンパク質の探索と機能解析

筑波大学 (University of Tsukuba)201

The ribosome-recycling step: consensus or controversy?

Ribosome recycling, the last step in translation, is now accepted as an essential process for prokaryotes. In 2005, three laboratories showed that ribosome-recycling factor (RRF) and elongation factor G (EF-G) cause dissociation of ribosomes into subunits, solving the long-standing problem of how this essential step of translation occurs. However, there remains ongoing controversy regarding the other actions of RRF and EF-G during ribosome recycling. We propose that the available data are consistent with the notion that RRF and EF-G not only split ribosomes into subunits but also participate directly in the release of deacylated tRNA and mRNA for the next round of translation

The role of GTP in transient splitting of 70S ribosomes by RRF (ribosome recycling factor) and EF-G (elongation factor G).

Ribosome recycling factor (RRF), elongation factor G (EF-G) and GTP split 70S ribosomes into subunits. Here, we demonstrated that the splitting was transient and the exhaustion of GTP resulted in re-association of the split subunits into 70S ribosomes unless IF3 (initiation factor 3) was present. However, the splitting was observed with sucrose density gradient centrifugation (SDGC) without IF3 if RRF, EF-G and GTP were present in the SDGC buffer. The splitting of 70S ribosomes causes the decrease of light scattering by ribosomes. Kinetic constants obtained from the light scattering studies are sufficient to account for the splitting of 70S ribosomes by RRF and EF-G/GTP during the lag phase for activation of ribosomes for the log phase. As the amount of 70S ribosomes increased, more RRF, EF-G and GTP were necessary to split 70S ribosomes. In the presence of a physiological amount of polyamines, GTP and factors, even 0.6 microM 70S ribosomes (12 times higher than the 70S ribosomes for routine assay) were split. Spermidine (2 mM) completely inhibited anti-association activity of IF3, and the RRF/EF-G/GTP-dependent splitting of 70S ribosomes

Interleukin-17A upregulates receptor activator of NF-kappaB on osteoclast precursors.

IntroductionThe interaction between the immune and skeletal systems is evidenced by the bone loss observed in autoimmune diseases such as rheumatoid arthritis. In this paper we describe a new mechanism by which the immune cytokine IL-17A directly affects osteoclastogenesis.MethodsHuman CD14+ cells were isolated from healthy donors, cultured on dentine slices and coverslips and stimulated with IL-17A and/or receptor activator of NF-kappaB ligand (RANKL). Osteoclast differentiation was evaluated by gene expression, flow cytometry, tartrate-resistant acid phosphatase staining, fluorescence and electron microscopy. Physiologic bone remodelling was studied in wild-type (Wt) and IL-17A-/- mice using micro-computer tomography and serum RANKL/osteoprotegerin concentration. Functional osteoclastogenesis assays were performed using bone marrow macrophages isolated from IL-17A-/- and Wt mice.ResultsIL-17A upregulates the receptor activator for NF-kappaB receptor on human osteoclast precursors in vitro, leading to increased sensitivity to RANKL signalling, osteoclast differentiation and bone loss. IL-17A-/- mice have physiological bone homeostasis indistinguishable from Wt mice, and bone marrow macrophages isolated from these mice develop fully functional normal osteoclasts.ConclusionsCollectively our data demonstrate anti-IL-17A treatment as a selective therapeutic target for bone loss associated with autoimmune diseases

CCR8 leads to eosinophil migration and regulates neutrophil migration in murine allergic enteritis

Allergic enteritis (AE) is a gastrointestinal form of food allergy. This study aimed to elucidate cellular and molecular mechanisms of AE using a murine model. To induce AE, BALB/c wild type (WT) mice received intraperitoneal sensitization with ovalbumin (an egg white allergen) plus ALUM and feeding an egg white (EW) diet. Microarray analysis showed enhanced gene expression of CC chemokine receptor (CCR) 8 and its ligand, chemokine CC motif ligand (CCL) 1 in the inflamed jejunum. Histological and FACS analysis showed that CCR8 knock out (KO) mice exhibited slightly less inflammatory features, reduced eosinophil accumulation but accelerated neutrophil accumulation in the jejunums, when compared to WT mice. The concentrations of an eosinophil chemoattractant CCL11 (eotaxin-1), but not of IL-5, were reduced in intestinal homogenates of CCR8KO mice, suggesting an indirect involvement of CCR8 in eosinophil accumulation in AE sites by inducing CCL11 expression. The potential of CCR8 antagonists to treat allergic asthma has been discussed. However, our results suggest that CCR8 blockade may promote neutrophil accumulation in the inflamed intestinal tissues, and not be a suitable therapeutic target for AE, despite the potential to reduce eosinophil accumulation. This study advances our knowledge to establish effective anti-inflammatory strategies in AE treatment.Fil: Blanco-Pérez, Frank. Paul-ehrlich-institut;Fil: Kato, Yoichiro. Tokyo Women's Medical University;Fil: Gonzalez-Menendez, Irene. Universitätsklinikum Tübingen Medizinische Fakultät;Fil: Laiño, Jonathan Emiliano. Paul-ehrlich-institut;Fil: Ohbayashi, Masaharu. Toyohashi Sozo University;Fil: Burggraf, Manja. Paul-ehrlich-institut;Fil: Krause, Maren. Paul-ehrlich-institut;Fil: Kirberg, Jörg. Paul-ehrlich-institut;Fil: Iwakura, Yoichiro. Tokyo University Of Science;Fil: Martella, Manuela. Universitätsklinikum Tübingen Medizinische Fakultät;Fil: Quintanilla-Martinez, Leticia. Universitätsklinikum Tübingen Medizinische Fakultät;Fil: Shibata, Noriyuki. Tokyo Women's Medical University;Fil: Vieths, Stefan. Paul-ehrlich-institut;Fil: Scheurer, Stephan. Paul-ehrlich-institut;Fil: Toda, Masako. Paul-ehrlich-institut; . Tohoku University