␤1,3-N-acetylglucosaminyltransferase 2 (␤3GnT2) is a polylactosamine synthase that synthesizes a backbone structure of carbohydrate structures onto glycoproteins. Here we generated ␤3GnT2-deficient (␤3GnT2 ؊/؊ ) mice and showed that polylactosamine on N-glycans was markedly reduced in their immunological tissues. In WT mice, polylactosamine was present on CD28 and CD19, both known immune costimulatory molecules. However, polylactosamine levels on these molecules were reduced in ␤3GnT2 ؊/؊ mice. ␤3GnT2 ؊/؊ T cells lacking polylactosamine were more sensitive to the induction of intracellular calcium flux on stimulation with anti-CD3 /CD28 and proliferated more strongly than T cells from WT mice. ␤3GnT2 ؊/؊ B cells also showed hyperproliferation on BCR stimulation. Macrophages from ␤3GnT2 ؊/؊ mice had higher cell surface CD14 levels and enhanced responses to endotoxin. These results indicate that polylactosamine on Nglycans is a putative immune regulatory factor presumably suppressing excessive responses during immune reactions.␤-1,3-N-acetylglucosaminyltransferase ͉ glycosyltransferase ͉ hyperactivation ͉ immune response

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We have demonstrated that an Arabidopsis serine/arginine rich-like protein, atSR45a, interacts with other splicing factors and its expression is markedly induced by high-light stress, suggesting the involvement of atSR45a in the regulation of stress-responsive alternative splicing. A whole-genome tiling array identified the alternative splicing of genes regulated by atSR45a by comparing gene expression profiles in wild-type and knockout atSR45a (KO-sr45a) plants under high-light stress. The expression levels of genomic regions within 217 genes were significantly altered in the KO-sr45a plants compared with the wild-type plants. Many genes encoded factors involved in signal transduction, cell cycle and DNA processing, protein fate and transcription. A semi-quantitative reverse transcription-PCR (RT-PCR) analysis confirmed changes in the transcript levels and/or alternative splicing efficiency under high-light stress in 18 genes, suggesting that atSR45a affects directly or indirectly not only alternative splicing efficiency but also the transcription of these target genes. Changes in the expression of atSR45a in response to high-light stress temporally correlated with changes in the alternative splicing efficiency and transcript levels of three and one target genes, respectively. Sequencing of the alternatively spliced variants of three target genes showed that atSR45a suppresses the splicing efficiency of intron retention-type alternative splicing events. These findings indicated the importance of atSR45a to the diversification of the transcriptome under high-light stress.

Tebipenem pivoxil (TBPM-PI, ME1211) has been under development as the world's first oral carbapenem for treatment of otolaryngological/respiratory infections caused by drug-resistant S. pneumoniae in pediatric patients. In order to treat these infections effectively, it is important to design optimal dosing regimens based on the pharmacokinetics/pharmacodynamics (PK/PD) relationships, which can be characterized by clarifying the pharmacokinetics of tebipenem (TBPM) in the pediatric population. We therefore performed an population pharmacokinetic analysis using plasma TBPM concentrations obtained from pediatric patients with otolaryngological infection or bacterial pneumonia (0.5-16 years old; n=217, 395 points), after repeated oral administration of TBPM-PI at a dose of 4 or 6 mg/kg b.i.d. A one-compartment model with first-order absorption was adopted. In analysis, weight-normalized creatinine clearance (Ccr) and age were the most significant covariates that respectively explained inter-subject variability in weight-normalized apparent clearance (CL/F) and volume of distribution (Vd/F) of TBPM. The CL/F of TBPM increased with Ccr, and the Vd/F decreased with age. Based on the results of the present analysis, validity of the presently recommended dosage regimen of TBPM-PI in pediatric patients is discussed.

Abstract.Patients who have renal failure and are on dialysis therapy experience serious complications caused by low-molecular-weight uremic toxin proteins normally filtered by glomeruli and metabolized by proximal tubule cells (PTC). Dialysis-related amyloidosis is one such complication induced by systemic deposition of amyloid proteins derived from 12-kD ␤ 2 -microglobulin (␤ 2 -m). Despite the use of high-flux membrane hemodialysis devices and direct absorbent columns, the removal of ␤ 2 -m is suboptimal, because the effects are transient and insufficient. Megalin is expressed in the apical membranes of PTC and recognized as a multiligand endocytic receptor that binds numerous low-molecular-weight proteins, including ␤ 2 -m. This study tested the feasibility of an intracorporeal therapeutic model of continuous ␤ 2 -m removal using megalin-expressing cell implantation. By cell association and degradation assays, rat yolk sac-derived L2 cells were identified to internalize and degrade ␤ 2 -m via megalin. The cells were effectively implanted within the subcutaneous tissues of nude mice using a type I collagen scaffold and a method inducing local angiogenesis. After nephrectomy and intraperitoneal injection with 125 I-␤ 2 -m, it was found that the implanted cells took up the labeled ligand, efficiently removing it from the blood. Bioengineered implantation of megalin-expressing cells may represent a new supportive therapy for dialysis patients to compensate for the loss of renal protein metabolism and remove uremic toxin proteins.

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Podocytes have been shown to express classical cadherins in the early stage of glomerulogenesis, but it remains unclear whether podocytes in normal and pathological conditions express cadherins in the adult stage. To address this question, rat podocytes in the neonate, the adult and in puromycin aminonucleoside (PAN) nephrosis were examined by immunofluorescence microscopy using antibodies against alpha- and beta-catenins and anti-pan-cadherin antibody, and by immunoelectron microscopy using anti-alpha-catenin antibody. In the neonate, all the antibodies reacted with the junctional complex of podocytes in the S-shaped body stage. The staining disappeared during the capillary loop stage, when foot processes and slit diaphragms are formed. In the adult, podocytes were not stained with any of the antibodies, whereas distinct staining with the antibodies was detected in endothelial cells and mesangial cells in the glomerulus. These findings were identical in kidneys of PAN nephrosis; podocytes did not show any significant staining. These results indicate that the composition of intercellular junction molecules of podocytes in the adult is different from that of immature podocytes even under the pathological condition.

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