Impact of extracellular matrix on engraftment and maturation of pluripotent stem cell-derived cardiomyocytes in a rat myocardial infarct model

Pluripotent stem cell-derived cardiomyocytes show great promise in regenerating the heart after myocardial infarction; however, several uncertainties exist that must be addressed before clinical trials. One practical issue is graft survival following transplantation. Although a pro-survival cocktail with Matrigel has been shown to enhance graft survival, the use of Matrigel may not be clinically feasible. The purpose of this study was to test whether a hyaluronan-based hydrogel, HyStem, could be a substitute for Matrigel. Human induced pluripotent stem cell-derived cardiomyocytes diluted with HyStem alone, HyStem plus pro-survival factors, or a pro-survival cocktail with Matrigel (PSC/MG), were transplanted into a rat model of acute myocardial infarction. Histological analysis at 4 weeks post transplantation revealed that, among the three groups, recipients of PSC/MG showed the largest graft size. Additionally, the grafted cardiomyocytes in the recipients of PSC/MG had a more matured phenotype compared to those in the other two groups. These findings suggest that further studies will be required to enhance not only graft size, but also the maturation of grafted cardiomyocytes.ArticleScientific reports 7(1) : 8630-(2017)journal articl

COPII coat composition is actively regulated by luminal cargo maturation

Background Export from the ER is an essential process driven by the COPII coat, which forms vesicles at ER exit sites (ERESs) to transport mature secretory proteins to the Golgi. Although the basic mechanism of COPII assembly is known, how COPII machinery is regulated to meet varying cellular secretory demands is unclear. Results Here, we report a specialized COPII system that is actively recruited by luminal cargo maturation. Glycosylphosphatidylinositol-anchored proteins (GPI-APs) are luminal secretory proteins anchored to the membrane by the glycolipid GPI. After protein attachment in the ER lumen, lipid and glycan parts of the GPI anchor are remodeled. In yeast, GPI-lipid remodeling concentrates GPI-APs into specific ERESs. We found that GPI-glycan remodeling induces subsequent recruitment of the specialized ER export machinery that enables vesicle formation from these specific ERESs. First, the transmembrane cargo receptor p24 complex binds GPI-APs as a lectin by recognizing the remodeled GPI-glycan. Binding of remodeled cargo induces the p24 complex to recruit the COPII subtype Lst1p, specifically required for GPI-AP ER export. Conclusions Our results show that COPII coat recruitment by cargo receptors is not constitutive but instead is actively regulated by binding of mature ligands. Therefore, we reveal a novel functional link between luminal cargo maturation and COPII vesicle budding, providing a mechanism to adjust specialized COPII vesicle production to the amount and quality of their luminal cargos that are ready for ER exit. This helps to understand how the ER export machinery adapts to different needs for luminal cargo secretion.This work was supported by grants from the Spanish Ministry of Science and Innovation BFU2008-04119 (to M.M.), BFU2011-24513 (to M.M.), BFU2009-07290 (to V.G.), and BFU2010-21339 (to R.E.W.); Junta de Andalucia P09-CVI-4503 (to M.M.) and P11-CTS-7962 (to R.E.W.); Swiss National Science Foundation and the NCCR Chemical Biology (to H.R.); the Max-Planck Society (to P.H.S.); the RIKEN-Max-Planck Joint Center for Chemical Biology (to D.V.S.); by JSPS KAKENHI grant number 21580094 (to K.F.); University of Seville fellowships (to A.A.-R., J.M.-L., and A.M.P.-L.); and Ramon y Cajal program (to V.G.). We are grateful to Servicios de Biología y Microscopía (CITIUS, Universidad de Sevilla)

Amelioration of Pulmonary Fibrosis by Matrix Metalloproteinase-2 Overexpression

Idiopathic pulmonary fibrosis is a progressive and fatal disease with a poor prognosis. Matrix metalloproteinase-2 is involved in the pathogenesis of organ fibrosis. The role of matrix metalloproteinase-2 in lung fibrosis is unclear. This study evaluated whether overexpression of matrix metalloproteinase-2 affects the development of pulmonary fibrosis. Lung fibrosis was induced by bleomycin in wild-type mice and transgenic mice overexpressing human matrix metalloproteinase-2. Mice expressing human matrix metalloproteinase-2 showed significantly decreased infiltration of inflammatory cells and inflammatory and fibrotic cytokines in the lungs compared to wild-type mice after induction of lung injury and fibrosis with bleomycin. The computed tomography score, Ashcroft score of fibrosis, and lung collagen deposition were significantly reduced in human matrix metalloproteinase transgenic mice compared to wild-type mice. The expression of anti-apoptotic genes was significantly increased, while caspase-3 activity was significantly reduced in the lungs of matrix metalloproteinase-2 transgenic mice compared to wild-type mice. Active matrix metalloproteinase-2 significantly decreased bleomycin-induced apoptosis in alveolar epithelial cells. Matrix metalloproteinase-2 appears to protect against pulmonary fibrosis by inhibiting apoptosis of lung epithelial cells

COPII Coat Composition Is Actively Regulated by Luminal Cargo Maturation

SummaryBackgroundExport from the ER is an essential process driven by the COPII coat, which forms vesicles at ER exit sites (ERESs) to transport mature secretory proteins to the Golgi. Although the basic mechanism of COPII assembly is known, how COPII machinery is regulated to meet varying cellular secretory demands is unclear.ResultsHere, we report a specialized COPII system that is actively recruited by luminal cargo maturation. Glycosylphosphatidylinositol-anchored proteins (GPI-APs) are luminal secretory proteins anchored to the membrane by the glycolipid GPI. After protein attachment in the ER lumen, lipid and glycan parts of the GPI anchor are remodeled. In yeast, GPI-lipid remodeling concentrates GPI-APs into specific ERESs. We found that GPI-glycan remodeling induces subsequent recruitment of the specialized ER export machinery that enables vesicle formation from these specific ERESs. First, the transmembrane cargo receptor p24 complex binds GPI-APs as a lectin by recognizing the remodeled GPI-glycan. Binding of remodeled cargo induces the p24 complex to recruit the COPII subtype Lst1p, specifically required for GPI-AP ER export.ConclusionsOur results show that COPII coat recruitment by cargo receptors is not constitutive but instead is actively regulated by binding of mature ligands. Therefore, we reveal a novel functional link between luminal cargo maturation and COPII vesicle budding, providing a mechanism to adjust specialized COPII vesicle production to the amount and quality of their luminal cargos that are ready for ER exit. This helps to understand how the ER export machinery adapts to different needs for luminal cargo secretion