Leukocytapheresis Therapy Improved Cholestasis in a Patient Suffering from Primary Sclerosing Cholangitis with Ulcerative Colitis

Primary sclerosing cholangitis (PSC) is an autoimmune disease of the hepatobiliary system for which effective therapy has not been established. Leukocytapheresis (LCAP) therapy is known to effective in patients with ulcerative colitis (UC). In addition, effects of LCAP therapy were reported on some autoimmune diseases such as Crohn's disease, rheumatoid arthritis and rapidly progressive glomerulonephritis. Here we report the case of a 29-year-old man with PSC associated with UC who was treated with LCAP therapy. He had a 16-year history of UC and a 12-year history of PSC. Although he was under treatment with prednisolone and ursodeoxycholic acid, exacerbation of UC and PSC-associated cholestasis were seen. Since he showed side effects of prednisolone, he was treated with LCAP. Not only improvement of UC, but also decreased serum alkaline phosphatase, γ-guanosine triphosphate and total bile acids, suggesting improvement of PSC-associated cholestaisis, were seen after treatment with LCAP. Our experience with this case suggests that LCAP therapy could be a new effective therapeutic strategy for patients with PSC associated with UC

Reciprocal interaction with G-actin and tropomyosin is essential for aquaporin-2 trafficking

Trafficking of water channel aquaporin-2 (AQP2) to the apical membrane and its vasopressin and protein kinase A (PKA)–dependent regulation in renal collecting ducts is critical for body water homeostasis. We previously identified an AQP2 binding protein complex including actin and tropomyosin-5b (TM5b). We show that dynamic interactions between AQP2 and the actin cytoskeleton are critical for initiating AQP2 apical targeting. Specific binding of AQP2 to G-actin in reconstituted liposomes is negatively regulated by PKA phosphorylation. Dual color fluorescence cross-correlation spectroscopy reveals local AQP2 interaction with G-actin in live epithelial cells at single-molecule resolution. Cyclic adenosine monophosphate signaling and AQP2 phosphorylation release AQP2 from G-actin. In turn, AQP2 phosphorylation increases its affinity to TM5b, resulting in reduction of TM5b bound to F-actin, subsequently inducing F-actin destabilization. RNA interference–mediated knockdown and overexpression of TM5b confirm its inhibitory role in apical trafficking of AQP2. These findings indicate a novel mechanism of channel protein trafficking, in which the channel protein itself critically regulates local actin reorganization to initiate its movement

Behçetʼs disease complicated by ileocecal and esophageal perforation

　A 36-year-old Japanese man known to have incomplete Behçet’s disease (oral aphthous ulcers, genital ulcers, skin lesions, and esophageal and ileocecal ulcers) was admitted to our hospital in January 2011 for abdominal pain. We administered corticosteroids and immunosuppressants. Two months later, we performed an ileocecal resection to control gastrointestinal bleeding from the ileocecal ulcers. High fever persisted after this surgery, and upper gastrointestinal endoscopy demonstrated ulcer penetration between the lower and abdominal esophagus. Eighteen days after the initial ileocecal resection, we performed a lower esophagus resection, gastric tube reconstruction and enterostomy, during which we confirmed a 5-mm-dia. perforated site at the posterior wall of the abdominal esophagus. Postoperative anastomotic leakage and empyema occurred, but they were relieved by thoracic drainage and empyema dissection

Systematic Cys mutagenesis of FlgI, the flagellar P-ring component of Escherichia coli

The bacterial flagellar motor is embedded in the cytoplasmic membrane, and penetrates the peptidoglycan layer and the outer membrane. A ring structure of the basal body called the P ring, which is located in the peptidoglycan layer, is thought to be required for smooth rotation and to function as a bushing. In this work, we characterized 32 cysteine-substituted Escherichia coli P-ring protein FlgI variants which were designed to substitute every 10th residue in the 346 aa mature form of FlgI. Immunoblot analysis against FlgI protein revealed that the cellular amounts of five FlgI variants were significantly decreased. Swarm assays showed that almost all of the variants had nearly wild-type function, but five variants significantly reduced the motility of the cells, and one of them in particular, FlgI G21C, completely disrupted FlgI function. The five residues that impaired motility of the cells were localized in the N terminus of FlgI. To demonstrate which residue(s) of FlgI is exposed to solvent on the surface of the protein, we examined cysteine modification by using the thiol-specific reagent methoxypolyethylene glycol 5000 maleimide, and classified the FlgI Cys variants into three groups: well-, moderately and less-labelled. Interestingly, the well- and moderately labelled residues of FlgI never overlapped with the residues known to be important for protein amount or motility. From these results and multiple alignments of amino acid sequences of various FlgI proteins, the highly conserved region in the N terminus, residues 1–120, of FlgI is speculated to play important roles in the stabilization of FlgI structure and the formation of the P ring by interacting with FlgI molecules and/or other flagellar components

Expression of the endoplasmic reticulum molecular chaperone (ORP150) rescues hippocampal neurons from glutamate toxicity

金沢大学医薬保健研究域医学系A series of events initiated by glutamate-receptor interaction perturbs cellular homeostasis resulting in elevation of intracellular free calcium and cell death. Cells subject to such environmental change express stress proteins, which contribute importantly to maintenance of metabolic homeostasis and viability. We show that an inducible chaperone present in endoplasmic reticulum (ER), the 150-kDa oxygen-regulated protein (ORP150), is expressed both in the human brain after seizure attack and in mouse hippocampus after kainate administration. Using mice heterozygous for ORP150 deficiency, exposure to excitatory stimuli caused hippocampal neurons to display exaggerated elevation of cytosolic calcium accompanied by activation of μ-calpain and cathepsin B, as well as increased vulnerability to glutamate-induced cell death in vitro and decreased survival to kainate in vivo. In contrast, targeted neuronal overexpression of ORP150 suppressed each of these events and enhanced neuronal and animal survival in parallel with diminished seizure intensity. Studies using cultured hippocampal neurons showed that ORP150 regulates cytosolic free calcium and activation of proteolytic pathways causing cell death in neurons subject to excitatory stress. Our data underscore a possible role for ER stress in glutamate toxicity and pinpoint a key ER chaperone, ORP150, which contributes to the stress response critical for neuronal survival

Roles of the Intramolecular Disulfide Bridge in MotX and MotY, the Specific Proteins for Sodium-Driven Motors in Vibrio spp.

The proteins PomA, PomB, MotX, and MotY are essential for the motor function of Na(+)-driven flagella in Vibrio spp. Both MotY and MotX have the two cysteine residues (one of which is in a conserved tetrapeptide [CQLV]) that are inferred to form an intramolecular disulfide bond. The cysteine mutants of MotY prevented the formation of an intramolecular disulfide bond, which is presumably important for protein stability. Disruption of the disulfide bridge in MotX by site-directed mutagenesis resulted in increased instability, which did not, however, affect the motility of the cells. These lines of evidence suggest that the intramolecular disulfide bonds are involved in the stability of both proteins, but only MotY requires the intramolecular bridge for proper function