Chimera Protein (chimera + protein)

Distribution by Scientific Domains

Selected Abstracts

Dynamics of the endoplasmic reticulum during early development of Drosophila melanogaster

CYTOSKELETON, Issue 3 2003
Yves Bobinnec
Abstract In this study, we analyze for the first time endoplasmic reticulum (ER) dynamics and organization during oogenesis and embryonic divisions of Drosophila melanogaster using a Protein Disulfide Isomerase (PDI) GFP chimera protein. An accumulation of ER material into the oocyte takes place during the early steps of oogenesis. The compact organization of ER structures undergoes a transition to an expanded reticular network at fertilization. At the syncytial stage, this network connects to the nuclear envelope as each nucleus divides. Time-lapse confocal microscopy on PDI transgenic embryos allowed us to characterize a rapid redistribution of the ER during the mitotic phases. The ER network is massively recruited to the spindle poles in prophase. During metaphase most of the ER remains concentrated at the spindle poles and shortly thereafter forms several layers of membranes along the ruptured nuclear envelope. Later, during telophase an accumulation of ER material occurs at the spindle equator. We also analyzed the subcellular organization of the ER network at the ultrastructural level, allowing us to corroborate the results from confocal microscopy studies. This dynamic redistribution of ER suggests an unexpected regulatory function for this organelle during mitosis. Cell Motil. Cytoskeleton 54:217,225, 2003. 2003 Wiley-Liss, Inc. [source]

Homo-oligomer formation by basigin, an immunoglobulin superfamily member, via its N-terminal immunoglobulin domain

FEBS JOURNAL, Issue 14 2000
Seiya Yoshida
Basigin (Bsg) is a highly glycosylated transmembrane protein with two immunoglobulin (Ig)-like domains. A number of studies, including gene targeting, have demonstrated that Bsg plays pivotal roles in spermatogenesis, implantation, neural network formation and tumor progression. In the present study, to understand the mechanism of action of Bsg, we determined its expression status on the plasma membrane. Cotransfection of Bsg expression vectors with two different tags clarified that Bsg forms homo-oligomers in a cis -dependent manner on the plasma membrane. If the disulfide bond of the more N-terminally located Ig-like domain was destroyed by mutations, Bsg could not form oligomers. In contrast, the mutations of the C-terminal Ig-like domain or N-glycosylation sites did not affect the association. The association of mouse and human Bsgs, which exhibit high homology in the transmembrane and intracellular domains but low homology in the extracellular domain, was very weak as compared with that within the same species, suggesting the importance of the extracellular domain in the association. If the extracellular domain of the human Ret protein was replaced with the N-terminal Ig-like domain of Bsg, the resulting chimera protein was associated with intact wild-type Bsg, but not if the C-terminal Ig-like domain, instead of the N-terminal one, of Bsg was used. No oligomer formation took place between the intact wild-type Ret and Bsg proteins. In conclusion, these data indicate that the N-terminal Ig-like domain is necessary and sufficient for oligomer formation by Bsg on the plasma membrane. [source]

Critical roles of VEGF-C-VEGF receptor 3 in reconnection of the collecting lymph vessels in mice

ABSTRACT Molecular mechanisms of reconnection of collecting lymph vessels were analyzed by using murine popliteal prenodal lymph vessels. At 1 and 2 weeks after being divided by cutting the lymph vessel, lymphatic reconnection was frequently observed accompanied by mesh-like lymphatic channels. Electron microscopic study also showed a monolayer of endothelial cells in the newly developed lymph vessels. Smooth muscle markers were immunofluorescently demonstrated in the wall of the new vessels. At 1 week after the procedure of cutting, augmented expressions of VEGF receptors 1, 2 and 3 were found immunohistochemically at the site of the reconnected lymph vessels. The expression of mRNA for VEGF receptor 3 was enhanced at 5 days and 1 week in small pieces of the tissues containing the reconnected lymph vessels, compared with that in the corresponding tissues obtained with sham operated ones. The administration of VEGF-C at the cutting site of the collecting lymph vessel significantly increased the rate of the reconnected lymph vessels, whereas additional treatment with Flt4/Fc chimera protein significantly reduced the rate of the reconnected ones. These results suggest that activation of VEGF-C-VEGF receptor 3 has critical roles in reconnection of the collecting lymph vessels in adult mice. [source]

Auraptene, a citrus fruit compound, regulates gene expression as a PPAR, agonist in HepG2 hepatocytes

BIOFACTORS, Issue 1 2008
Nobuyuki Takahashi
Abstract Citrus fruit compounds have various activities that improve pathological conditions in many tissues. In this study, we examined the effect of auraptene contained mainly in the peel of citrus on peroxisome proliferator-activated receptor-, (PPAR,) activation. To examine effects of auraptene on the PPAR, activation in hepatocytes, PPAR ligand assay system was developed using HepG2 hepatocytes, in which the endogenous PPAR, expression level is very low. In the PPAR ligand assay, the addition of auraptene showed significant effects on the transactivation of GAL4/PPAR, chimera proteins in a dose-dependent manner. Actually, treatment with auraptene induced the up-regulation of PPAR target genes, such as acyl-CoA oxidase (ACO), carnitine-palmitoyl transferase 1A (CPT1A) and acyl-CoA synthetase (ACS), in PPAR,-expressing HepG2 hepatocytes. The regulation of gene expression was dependent on PPAR, because mock-transfected HepG2 hepatocytes showed no regulation. The up-regulation of PPAR target gene expression by auraptene was sufficient to enhance oleic acid uptake into PPAR,-expressing HepG2 hepatocytes. These results indicate that auraptene acts as a PPAR, agonist in hepatocytes and that auraptene may improve lipid abnormality through PPAR, activation in the liver. [source]