The effect of lanthanum carbonate on calciprotein particles in hemodialysis patients.

BACKGROUND: Aggregation of solid-phase calcium-phosphate and fetuin-A form nanoparticles called calciprotein particles (CPP). Serum CPP levels are increased in CKD patients and correlated with vascular stiffness and calcification. In this study, we evaluated effects of lanthanum carbonate (LC) and calcium carbonate (CC) on serum CPP levels in hemodialysis (HD) patients. METHODS: Twenty-four (24) HD patients (50% men, age; 68 ± 12 years, dialysis period; 6.2 ± 4.8 years, Kt/v; 1.74 ± 0.34) were treated with CC during 0-8 weeks and then switched to LC during 9-16 weeks. Blood samples were obtained at 0, 8, 16 weeks. Serum CPP levels (TCPP) were measured by the gel-filtration method. Low-density CPP (LCPP) levels were determined by centrifuging the serum samples at 16,000 g for 2 h and measuring CPP levels in the supernatant. The difference between TCPP and LCPP was defined as the high-density CPP (HCPP) level. We evaluated association of TCPP, LCPP, and HCPP with serum calcium (Ca), phosphorus (P), intact PTH, FGF23, Klotho, fetuin-A, aortic calcification index (ACI), LDL cholesterol, and hs-CRP. RESULTS: TCPP and LCPP levels were significantly decreased after switching CC to LC, whereas Ca and P levels were not changed. HCPP levels were below the lower limit quantification in all patients. The changes in P, Ca × P, LDL cholesterol, but not ACI and the changes in hs-CRP, were correlated with the change in TCPP levels. CONCLUSION: The TCPP levels were significantly decreased after switching CC to LC. Non-calcium-containing phosphate binders may be preferable for lowering CPP levels.

A functional polypeptide N-acetylgalactosaminyltransferase (PGANT) initiates O-glycosylation in cultured silkworm BmN4 cells.

Mucin-type O-glycosylation is initiated by UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferases (ppGalNAc-Ts or PGANTs), attaching GalNAc to serine or threonine residue of a protein substrate. In the insect model from Lepidoptera, silkworm (Bombyx mori), however, O-glycosylation pathway is totally unexplored and remains largely unknown. In this study, as the first report regarding protein O-glycosylation analysis in silkworms, we verified the O-glycan profile that a common core 1 Gal (ß1-3) GalNAc disaccharide branch without terminally sialylated structure is mainly formed for a baculovirus-produced human proteoglycan 4 (PRG4) protein. Intriguingly, functional screenings in cultured silkworm BmN4 cells for nine Bmpgants reveal that Bmpgant2 is the solo functional BmPGANT for PRG4, implying that Bmpgants may have unique cell/tissue or protein substrate preferences. Furthermore, a recombinant BmPGANT2 protein was successfully purified from silkworm-BEVS and exhibited a high ability to transfer GalNAc for both peptide and protein substrates. Taken together, the present results clarified the functional BmPGANT2 in cultured silkworm cells, providing crucial fundamental insights for future studies dissecting the detailed silkworm O-glycosylation pathways and productions of glycoproteins with O-glycans.

Soaking RNAi-mediated modification of Sf9 cells for baculovirus expression system by ectopic expression of Caenorhabditis elegans SID-1.

RNA interference (RNAi) is a biological phenomenon that silences the expression of genes of interest. Passive double-stranded RNA (dsRNA) uptake has been uniquely observed in Caenorhabditis elegans due to the expression of systemic RNAi defective-1 (SID-1). We report that ectopic expression of CeSID-1 endows the Sf9 cells with a capacity for soaking RNAi. Soaking the Sf9-SID1 with dsRNA corresponding to either exogenous or endogenous target genes induced a significant decrease in the amount of mRNA or protein. These results enabled us to modify the target proteins of baculovirus expression vector system in both quantities and posttranslational modifications. The current low-cost and high-efficiency RNAi system is useful for high-throughput gene function analysis and mass production of recombinant protein.

Production and characterization of the celery mismatch endonuclease CEL II using baculovirus/silkworm expression system.

Mutation and polymorphism detection by nucleases has become a more important tool in clinical and biological researches. There are several kinds of single-stranded nucleases for detecting mismatched DNAs. One of them, CEL II, was isolated from Apium graveolens and cleaves DNA with high specificity at sites of mismatch. High-throughput mutation scanning requires large quantity of CEL II endonuclease. Here, we demonstrate high-level expression of CEL II using silkworm-baculovirus system. The recombinant CEL II secreted in silkworm hemolymph was glycosylated and susceptible to N-glycosidase F. Additionally, larger metal ions such as Ca(2+) and Sr(2+) were able to replace Mg(2+) and enhanced mismatch cleavage activity of CEL II. These results indicate that the silkworm-baculovirus platform is a good alternative system to obtain the functional CEL II.

RNAi suppression of ß-N-acetylglucosaminidase (BmFDL) for complex-type N-linked glycan synthesis in cultured silkworm cells.

Glycoproteins have various biological functions including enzymatic activity, protein stability and others. Due to the presence of paucimannosidic N-linked glycans, recombinant proteins from an insect cell expression system may not be suitable for therapeutic use. Because baculovirus expression systems (BESs) are used to produce recombinant proteins, it is of interest to modify the endogenous N-glycosylation pathway in insects to mimic that of mammals. Using a soaking RNAi sensitive cell line, BmN4-SID1, has enabled us to suppress Bombyx mori FDL (BmFDL), an N-linked glycan-specific ß-N-acetylglucosaminidase. Western blotting and MALDI-TOF MS demonstrated that the BmFDL depletion almost completely converted the paucimannosidic structures of the recombinant proteins produced by BES into a complex-type structure. This highly efficient, simple and low-cost method can be used for mass production of secretion proteins with complex-type N-linked glycans.

[A case of primary chondrosarcoma difficult to differentiate from retroperitoneal tumor].

A 57-year-old woman was admitted with chief complaints of pain in the right lower quadrant and weight loss. Contrast computed tomography of the abdomen revealed a tumor in the right inferior aspect of the liver. The patient was diagnosed with cystic renal cell carcinoma or lymphangioma, and she underwent surgery. The tumor was approached via upper abdominal midline incision and was found to be immobile. The tumor had adhered tightly to the right 12th rib and was resected along with the 12th rib. Gross pathology of the resected tissue revealed a jelly-like component inside, and the patient was histopathologically diagnosed with chondrosarcoma (grade 1). The patient is currently undergoing outpatient follow-up; a 1-year postoperative follow-up did not show any recurrence or metastasis. Chondrosarcoma accounts for approximately 20% of primary malignant bone tumors. It has a low response rate to both chemotherapy and radiotherapy, and surgical treatment remains the most effective method. Bone tumors must be considered in cases of atypical retroperitoneal tumors in which a definitive diagnosis cannot be made using diagnostic imaging.

Receptor activator of the NFκB ligand system protects renal function during experimental renal ischemia-reperfusion in mice.

Renal ischemia-reperfusion (I/R) injury is closely associated with delayed graft function and poor long-term graft survival following transplantation. Various pathophysiologies can cause the deterioration of renal function; however, the immune system plays important roles in promoting and protecting renal tissues. Receptor activator of NFκB ligand (RANKL) is a member of the TNF superfamily and is produced by bone-forming osteoblasts; the receptor for RANKL is called RANK. In bone biology, RANKL-RANK signaling has been extensively studied, but its roles in the immune system are still obscure. We investigated the role of the RANK system in I/R injury of the kidney using an experimental mouse I/R model. The left renal pedicles of 10-week-old male mice were clamped for 60 min, and reperfusion and right nephrectomy were simultaneously performed. Separate groups were administered an anti-RANKL antibody and recombinant RANKL (rRANKL) 24 h prior to I/R. After reperfusion for a set period of time, the serum creatinine level was measured, and the left kidney was removed for histological examination and western blotting to evaluate the expression and localization of RANK-associated molecules and cytokines. The serum creatinine levels were significantly elevated after I/R injury. A time-dependent increase in RANKL was observed up to 24 h, whereas RANK was induced for 12 h after reperfusion. RANK was expressed in infiltrating inflammatory cells, which were positive for CD68, a marker of monocytes/macrophages. The pre-treatment with the anti-RANKL antibody significantly impaired renal function and increased the induction of inflammatory cytokines (TNFα and IL-6), Toll-like receptor (TLR4) and MyD88 (all p < .05) compared to the levels in the I/R group. However, rRANKL significantly improved renal function and decreased the levels of inflammatory cytokines (TNFα and IL-6), TLR4 and MyD88 (p < .05) compared to those in the I/R group. The present study is the first to evaluate the role of the RANK system in renal I/R injury. RANKL-RANK signaling affects macrophage function and results in the downregulation of TLR4 and reduction in TNFα and IL-6, leading to improved renal function following I/R injury.

Anti-TNF-α Agent Infliximab and Splenectomy Are Protective Against Renal Ischemia-Reperfusion Injury.

BACKGROUND: Renal ischemia-reperfusion (I/R) injury is associated with delayed graft function and results in poor long-term graft survival. We previously showed that splenectomy (SPLN) protects the kidney from I/R injury and reduces serum TNF-α levels. Herein, we further investigated the effects of SPLN on inflammatory responses and tissue injury in renal I/R by examining the expression of major inflammatory cytokines and heat shock protein 70 (HSP70). Because it was shown previously that the anti-TNF-α agent infliximab (IFX) attenuated renal I/R injury, we also investigated whether IFX administration mimics the effects of SPLN. METHODS: The left renal pedicles of adult male Wistar rats were clamped for 45 minutes and then reperfused for 24 hours; right nephrectomy and SPLN were performed immediately. A separate cohort was administered IFX 1 hour before surgery in lieu of SPLN. RESULTS: Serum creatinine and blood urea nitrogen levels were markedly elevated by I/R injury; these increases were significantly reversed by IFX. Furthermore, IFX inhibited the induction of inflammatory cytokines and HSP70 during renal I/R injury. Time-dependent profiles revealed that the expression of inflammatory cytokines was elevated immediately after I/R, whereas levels of HSP70, serum creatinine, and blood urea nitrogen began to rise 3 hours postreperfusion. Macrophages/monocytes were significantly increased in I/R-injured kidneys, but not in those administered IFX. The outcomes of SPLN mirrored those of IFX administration. CONCLUSIONS: Splenectomy and TNF-α inhibition both protect the kidney from I/R injury by reducing the accumulation of renal macrophages/monocytes and induction of major inflammatory cytokines.

Mass Production of an Active Peptide-N-Glycosidase F Using Silkworm-Baculovirus Expression System.

The peptide-N (4)-(N-acetyl-ß-D-glucosaminyl) asparagine amidase F (PNGase F) catalyzes the cleavage of N-linked oligosaccharides between the innermost GlcNAc and asparagine residues of high mannose, hybrid and complex oligosaccharides from glycoproteins. The PNGase F has broad substrate specificity and thus is extensively used for the structural and functional studies of the glycoproteins. In this study, we tried to produce active recombinant PNGase F as secreted and intracellular-expressed forms using baculovirus expression vector system (BEVS) through silkworm larvae or cultured cells. PNGase F itself contains potential N-linked glycosylation sites and we found that it was N-glycosylated when PNGase F secreted from silkworm cells. Intriguingly, the secreted recombinant PNGase F has the lower catalytic activity and self-digests its N-linked glycans and therefore this secreted form of this enzyme produced from BEVS is not appropriate for carbohydrate chain analysis. Instead, we successfully mass-produced (2.1 mg/20 silkworm larvae) and purified active recombinant PNGase F as an intracellular protein without N-glycosylations. Besides, we confirmed by directed mutagenesis that several amino acid residues are crucial for the function of PNGase F. Our results provide an alternative method for the mass production of active enzymes involved in the study of glycoproteins.

Expression, purification, and characterization of endo-ß-N-acetylglucosaminidase H using baculovirus-mediated silkworm protein expression system.

Endo-ß-N-acetylglucosaminidase (Endo H) from Streptomyces plicatus hydrolyzes the core di-GlcNAc units of asparagine-linked oligosaccharides and is regarded as an important tool for glycobiology research. In the present study, we established a large-scale system to produce secreted Endo H using a silkworm-baculovirus expression system (silkworm-BES). The recombinant Endo H purified from silkworm hemolymph had activity comparable to that from recombinant Escherichia coli. As well as its well-characterized substrate RNase B, the Endo H from silkworm-BES was able to deglycosylate the high-mannose glycoproteins from silkworm hemolymph. Interestingly, the secretion amount of recombinant Endo H was significantly varied among the different silkworm strains, which could provide valuable information for larger-scale protein productions from silkworm-BES.