CD109 Attenuates Bleomycin-induced Pulmonary Fibrosis by Inhibiting TGF-ß Signaling.

Pulmonary fibrosis is a fatal condition characterized by fibroblast and myofibroblast proliferation and collagen deposition. TGF-ß plays a pivotal role in the development of pulmonary fibrosis. Therefore, modulation of TGF-ß signaling is a promising therapeutic strategy for treating pulmonary fibrosis. To date, however, interventions targeting TGF-ß have not shown consistent efficacy. CD109 is a GPI-anchored glycoprotein that binds to TGF-ß receptor I and negatively regulates TGF-ß signaling. However, no studies have examined the role and therapeutic potential of CD109 in pulmonary fibrosis. The purpose of this study was to determine the role and therapeutic value of CD109 in bleomycin-induced pulmonary fibrosis. CD109-transgenic mice overexpressing CD109 exhibited significantly attenuated pulmonary fibrosis, preserved lung function, and reduced lung fibroblasts and myofibroblasts compared with wild-type (WT) mice. CD109-/- mice exhibited pulmonary fibrosis comparable to WT mice. CD109 expression was induced in variety types of cells, including lung fibroblasts and macrophages, upon bleomycin exposure. Recombinant CD109 protein inhibited TGF-ß signaling and significantly decreased ACTA2 expression in human fetal lung fibroblast cells in vitro. Administration of recombinant CD109 protein markedly reduced pulmonary fibrosis in bleomycin-treated WT mice in vivo. Our results suggest that CD109 is not essential for the development of pulmonary fibrosis, but excess CD109 protein can inhibit pulmonary fibrosis development, possibly through suppression of TGF-ß signaling. CD109 is a novel therapeutic candidate for treating pulmonary fibrosis.

Uric acid is a major chemical constituent for the whitish coloration in the medaka leucophores.

In whitish parts of teleost skin, the coloration is attributed to a light scattering phenomenon within light-reflecting chromatophores, namely leucophores and iridophores, which contain high refractive index materials in their cytoplasmic organelles, leucosomes and light-reflecting platelets, respectively. Previous chemical examinations revealed that guanine is a major constituent of the materials in the platelets of the iridophores, while, in leucophores, the detailed chemical nature of the materials contained in the leucosomes has not been reported. Here, using liquid chromatography-tandem mass spectroscopy, we investigated the chemical features of materials eluted from scales, larvae, and single chromatophores of the medaka. Results of the liquid chromatography-tandem mass spectroscopy suggested that uric acid is a major constituent of the high refractive index materials in medaka leucophores and is a unique marker to investigate the presence of leucophores in the fish. The whitish appearance of the medaka leucophores may be attributed to the light-scattering phenomenon in leucosomes, which contain highly concentrated uric acid.

Measurement of surface topography and stiffness distribution on cross-section of Xenopus laevis tailbud for estimation of mechanical environment in embryo.

The stress distribution inside a Xenopus laevis tailbud embryo was estimated to examine the cause of the straightening and elongation. The embryos were cut in the middle, yielding a cross-section perpendicular to the body axis. The section was not flat, owing to the residual stress relief. The stress needed to restore the flatness corresponded to the stress inside the embryo and was calculated using the surface topography and Young's-moduli in the section. We found the areas of the notochord (Nc), neural tube (NT), and abdominal tissue (AT) bulged in the cross-section, which revealed that compressive forces acted in these tissues. The moduli of the Nc, NT, and AT were in the order of several thousand, hundred, and tens of pascals, respectively. In the Nc, the compressive force was largest and increased with the development, suggesting Nc playing a central role in the elongation. The bending moment generated by the AT was 10 times higher than that by the Nc in the early stages of the tailbud formation, and the two were similar in the latter stages, suggesting that the compressive force in the AT was the major cause of the straightening during the early stage. The straightening and elongation could be orchestrated by changes in the compressive forces acting on the Nc, NT, and AT over time. For the sake of simplicity, we calculated the compressive force only and neglected the tensile force. Thus, it should be noted that the amount of the compressive force was somewhat overestimated.

SHISA6 Confers Resistance to Differentiation-Promoting Wnt/ß-Catenin Signaling in Mouse Spermatogenic Stem Cells.

In the seminiferous tubules of mouse testes, a population of glial cell line-derived neurotrophic factor family receptor alpha 1 (GFRα1)-positive spermatogonia harbors the stem cell functionality and supports continual spermatogenesis, likely independent of asymmetric division or definitive niche control. Here, we show that activation of Wnt/ß-catenin signaling promotes spermatogonial differentiation and reduces the GFRα1+ cell pool. We further discovered that SHISA6 is a cell-autonomous Wnt inhibitor that is expressed in a restricted subset of GFRα1+ cells and confers resistance to the Wnt/ß-catenin signaling. Shisa6+ cells appear to show stem cell-related characteristics, conjectured from the morphology and long-term fates of T (Brachyury)+ cells that are found largely overlapped with Shisa6+ cells. This study proposes a generic mechanism of stem cell regulation in a facultative (or open) niche environment, with which different levels of a cell-autonomous inhibitor (SHISA6, in this case) generates heterogeneous resistance to widely distributed differentiation-promoting extracellular signaling, such as WNTs.

G protein-coupled receptors Flop1 and Flop2 inhibit Wnt/ß-catenin signaling and are essential for head formation in Xenopus.

Patterning of the vertebrate anterior-posterior axis is regulated by the coordinated action of growth factors whose effects can be further modulated by upstream and downstream mediators and the cross-talk of different intracellular pathways. In particular, the inhibition of the Wnt/ß-catenin signaling pathway by various factors is critically required for anterior specification. Here, we report that Flop1 and Flop2 (Flop1/2), G protein-coupled receptors related to Gpr4, contribute to the regulation of head formation by inhibiting Wnt/ß-catenin signaling in Xenopus embryos. Using whole-mount in situ hybridization, we showed that flop1 and flop2 mRNAs were expressed in the neural ectoderm during early gastrulation. Both the overexpression and knockdown of Flop1/2 resulted in altered embryonic head phenotypes, while the overexpression of either Flop1/2 or the small GTPase RhoA in the absence of bone morphogenetic protein (BMP) signaling resulted in ectopic head induction. Examination of the Flops' function in Xenopus embryo animal cap cells showed that they inhibited Wnt/ß-catenin signaling by promoting ß-catenin degradation through both RhoA-dependent and -independent pathways in a cell-autonomous manner. These results suggest that Flop1 and Flop2 are essential regulators of Xenopus head formation that act as novel inhibitory components of the Wnt/ß-catenin signaling pathway.

PRICKLE1 interaction with SYNAPSIN I reveals a role in autism spectrum disorders.

The frequent comorbidity of Autism Spectrum Disorders (ASDs) with epilepsy suggests a shared underlying genetic susceptibility; several genes, when mutated, can contribute to both disorders. Recently, PRICKLE1 missense mutations were found to segregate with ASD. However, the mechanism by which mutations in this gene might contribute to ASD is unknown. To elucidate the role of PRICKLE1 in ASDs, we carried out studies in Prickle1(+/-) mice and Drosophila, yeast, and neuronal cell lines. We show that mice with Prickle1 mutations exhibit ASD-like behaviors. To find proteins that interact with PRICKLE1 in the central nervous system, we performed a yeast two-hybrid screen with a human brain cDNA library and isolated a peptide with homology to SYNAPSIN I (SYN1), a protein involved in synaptogenesis, synaptic vesicle formation, and regulation of neurotransmitter release. Endogenous Prickle1 and Syn1 co-localize in neurons and physically interact via the SYN1 region mutated in ASD and epilepsy. Finally, a mutation in PRICKLE1 disrupts its ability to increase the size of dense-core vesicles in PC12 cells. Taken together, these findings suggest PRICKLE1 mutations contribute to ASD by disrupting the interaction with SYN1 and regulation of synaptic vesicles.