[Show abstract][Hide abstract] ABSTRACT: When we treated rat bone marrow stromal cells (rBMSCs) with neuronal differentiation induction media, typical unfolded protein response (UPR) was observed. BIP/GRP78 protein expression was time-dependently increased, and three branches of UPR were all activated. ATF6 increased the transcription of XBP1 which was successfully spliced by IRE1. PERK was phosphorylated and it was followed by eIF2alpha phosphorylation. Transcription of two downstream targets of eIF2alpha, ATF4 and CHOP/GADD153, were transiently up-regulated with the peak level at 24 h. Immunocytochemical study showed clear coexpression of BIP and ATF4 with NeuN and Map2, respectively. UPR was also observed during the neuronal differentiation of mouse embryonic stem (mES) cells. Finally, chemical endoplasmic reticulum (ER) stress inducers, thapsigargin, tunicamycin, and brefeldin A, dose-dependently increased both mRNA and protein expressions of NF-L, and, its expression was specific to BIP-positive rBMSCs. Our results showing the induction of UPR during neuronal differentiations of rBMSCs and mES cells as well as NF-L expression by ER stress inducers strongly suggest the potential role of UPR in neuronal differentiation.
Full-text · Article · Apr 2009 · Experimental and Molecular Medicine
[Show abstract][Hide abstract] ABSTRACT: Apoptosis contributes to cyclosporine (CsA)-induced renal cell death. This study tested the effects of CsA-induced endoplasmic reticulum (ER) stress on apoptotic cell death in an experimental model of chronic CsA nephropathy.
CsA (15 mg/kg per day) was given to rats for 7 or 28 days. The ER stress response was evaluated with BiP expression, and the proapoptotic response was assessed with CHOP and caspase 12 expression. ER structure was evaluated by transmission electron microscopy, and apoptotic cell death was detected with TUNEL staining.
Short-term treatment of CsA for 7 days activated both the ER stress response (induction of BiP mRNA and protein) and the proapoptotic response (upregulation of caspase 12 and CHOP mRNAs and proteins). However, long-term treatment with CsA for 28 days decreased BiP and further increased CHOP. The imbalance between the two responses coincided with the timing of the appearance of apoptotic cell death and the disruption of the ER structure.
Prolonged CsA-induced ER stress causes apoptotic cell death by depleting molecular chaperones and activating the proapoptotic pathway.
No preview · Article · May 2008 · American Journal of Nephrology
[Show abstract][Hide abstract] ABSTRACT: Epoxy polymers containing phosphorylcholine (PC) groups were prepared by the copolymerization of glycidyl methacrylate and 2-methacryloyloxyethyl phosphorylcholine (MPC), and used as a coating material for an oxygen sensing membrane, in order to protect it against bio-fouling by microorganisms. The copolymers had good film forming properties. The cured polymer films had excellent adhesion properties and were transparent at the wavelength of more than 300nm. The cross-linking reaction of the polymer films increased with increasing amount of MPC units in the copolymer, and the addition of an aliphatic diamine significantly enhanced the cross-linking reaction of the copolymer films. The cured epoxy copolymers show a high anti-fouling effect, which was observed by incubating E. coli on the copolymer films. The coatings of the cured epoxy copolymer did not interfere with the performance of the optical oxygen sensing membrane. Thus, the epoxy copolymers containing PC groups are very useful as an anti-fouling coating material for the optical biosensing membranes.
Preview · Article · Jun 2007 · Sensors and Actuators B Chemical
[Show abstract][Hide abstract] ABSTRACT: Brain/kidney (B/K) protein is a novel double C2-like-domain protein that is highly expressed in rat brain and kidney, but its cellular localization and functional role in the kidney are still undetermined. We examined the cellular localization of B/K protein in the rat kidney under normal and ischemic conditions. Ischemia-reperfusion (I/R) injury was induced by clamping both renal arteries for 45 min, and animals were killed at 1 and 6 h and 1, 2, 3, 5, 7, 14, and 28 days after the reperfusion. Kidney tissues were processed for immunohistochemistry and immunoblot analyses using rabbit anti-B/K polyclonal antibodies. In control kidneys, B/K protein was expressed primarily in distal tubules including the thick ascending limb, distal convoluted and connecting tubules, and collecting duct. Notably, B/K protein was also expressed in the straight portion (S3 segment), but not in the S1 or S2, of proximal tubules, and podocytes of the glomerulus. In rat kidneys with I/R injury, expression of B/K protein was differentially regulated according to the anatomic location. In distal tubules, overall expression of B/K protein was markedly decreased. On the other hand, I/R injury significantly increased B/K protein expression in the S3 segment of the outer medulla as well as in the rat proximal tubular epithelial cell line NRK-52E in vitro. Furthermore, B/K protein was strongly expressed in many exfoliated cells in the lumen and urine. These findings suggest that B/K protein is closely associated with cell death in proximal tubules, which are vulnerable to I/R injury in the kidney.
Full-text · Article · Feb 2007 · American journal of physiology. Renal physiology
[Show abstract][Hide abstract] ABSTRACT: The chemical structure of a semi-aromatic polyimide-I, which was prepared by the chemical imidization of cyclopentanetetracarboxylic
dianhydride and 2,2-bis(4-aminophenyl)hexafluoropropane, was characterized by13C-NMR spectroscopy. The chemically imidized polyimide-I was used for the preparation of a photosensitive polyimide (PSPI)|through
the addition of benzophenone and benzophenone oxime hexamethylene diurethane (BOHD), a photobase generator containing oxime-urethane
groups. The polyimide-I film containing benzophenone and BOHD was not soluble in 2.38 wt% tetrabutylammonium hydroxide solution
in H2O. However, it became soluble following irradiation with 310 nm UV light. A positive tone image with a resolution of 5 μm
was obtained with this PSPI, having sensitivity (D
c)|of 1.2 J/cm2 and contrast (γ
)|of 1.08. Thus, a polyimide, which is not intrinsically photosensitive, can become photosensitive through the addition of
a photobase generator containing oxime-urethane groups as a photosensitive compound.
Keywordsirradiation–photobase generator–positive photoresist–photosensitive polyimide–photosensitive compound
Preview · Article · Jun 2006 · Macromolecular Research