Clinical studies on cell-mediated immunity in patients with renal cell carcinoma: interleukin-2 and interferon-γ production of lymphocytes

Summary The authors examined interleukin-2 (IL-2) production and interferon (IFN) production of peripheral blood mononuclear cells in 28 patients with renal cell carcinoma and 17 control subjects. The peripheral blood was obtained prior to the initiation of therapeutic procedures. The patients were divided into two groups according to tumor size, 5 cm and >5 cm. The production of IL-2 and IFN was measured by immunoradiometric assay. As a result, in the patients with tumors >5 cm, IL-2 and IFN production was impaired. However, in the patients with tumors 5 cm, IFN production was enhanced, though IL-2 production was not significantly different from that of the control subjects. There was no significant correlation between IL-2 production and IFN production.     

Selective synthesis and retention of 66k protein in a human neuroblastoma cell line (NCG) treated with a cytotoxic dosage of delta 12-prostaglandin J2

delta 12-prostaglandin(PG)J2 (7.5 micrograms/ml) significantly inhibited protein synthesis and cell growth in a human neuroblastoma cell line (NCG), decreasing these factors by 31.5% and 78.2% of the control values, respectively. Two protein synthesis inhibitors, cycloheximide (CHM) and emetine, exhibited a dose-dependent protective effect for neuroblastoma cells against delta 12-PGJ2 cytotoxicity. At a concentration of 15 micrograms/ml CHM, the number of viable cells increased from 21.8% to 36.7% of the control value (p less than 0.01). The sodium dodecyl sulfate-polyacrylamide gel analysis of [35S]methionine-incorporated proteins revealed an increased synthesis of 86k, 70k and 66k proteins in the delta 12-PGJ2-treated NCG cells under the condition that delta 12-PGJ2 exerts cytotoxicity. Of these proteins, the amount of 66k protein was particularly increased in cell cytosol; however, its synthesis did not occur when CHM prohibited the delta 12-PGJ2 cytotoxic effect. When emetine was used instead of CHM, similar results were obtained. These results strongly suggest that the 66k protein plays a critical role in the delta 12-PGJ2 cytotoxicity.     

Amino acid sequence and carbohydrate-binding analysis of the N-acetyl-D-galactosamine-specific C-type lectin, CEL-I, from the Holothuroidea, Cucumaria echinata

CEL-I is one of the Ca2+-dependent lectins that has been isolated from the sea cucumber, Cucumaria echinata. This protein is composed of two identical subunits held by a single disulfide bond. The complete amino acid sequence of CEL-I was determined by sequencing the peptides produced by proteolytic fragmentation of S-pyridylethylated CEL-I. A subunit of CEL-I is composed of 140 amino acid residues. Two intrachain (Cys3-Cys14 and Cys31-Cys135) and one interchain (Cys36) disulfide bonds were also identified from an analysis of the cystine-containing peptides obtained from the intact protein. The similarity between the sequence of CEL-I and that of other C-type lectins was low, while the C-terminal region, including the putative Ca2+ and carbohydrate-binding sites, was relatively well conserved. When the carbohydrate-binding activity was examined by a solid-phase microplate assay, CEL-I showed much higher affinity for N-acetyl-D-galactosamine than for other galactose-related carbohydrates. The association constant of CEL-I for p-nitrophenyl N-acetyl-beta-D-galactosaminide (NP-GalNAc) was determined to be 2.3 x 10(4) M(-1), and the maximum number of bound NP-GalNAc was estimated to be 1.6 by an equilibrium dialysis experiment.     

The conformationally flexible S9-S10 linker region in the core domain of p53 contains a novel MDM2 binding site whose mutation increases ubiquitination of p53 in vivo

Although the N-terminal BOX-I domain of the tumor suppressor protein p53 contains the primary docking site for MDM2, previous studies demonstrated that RNA stabilizes the MDM2.p53 complex using a p53 mutant lacking the BOX-I motif. In vitro assays measuring the specific activity of MDM2 in the ligand-free and RNA-bound state identified a novel MDM2 interaction site in the core domain of p53. As defined using phage-peptide display, the RNA.MDM2 isoform exhibited a notable switch in peptide binding specificity, with enhanced affinity for novel peptide sequences in either p53 or small nuclear ribonucleoprotein-U (snRNP-U) and substantially reduced affinity for the primary p53 binding site in the BOX-I domain. The consensus binding site for the RNA.MDM2 complex within p53 is SGXLLGESXF, which links the S9-S10 beta-sheets flanking the BOX-IV and BOX-V motifs in the core domain and which is a site of reversible conformational flexibility in p53. Mutation of conserved amino acids in the linker at Ser(261) and Leu(264), which bridges the S9-S10 beta-sheets, stimulated p53 activity from reporter templates and increased MDM2-dependent ubiquitination of p53. Furthermore, mutation of the conserved Phe(270) within the S10 beta-sheet resulted in a mutant p53, which binds more stably to RNA.MDM2 complexes in vitro and which is strikingly hyper-ubiquitinated in vivo. Introducing an Ala(19) mutation into the p53(F270A) protein abolished both RNA.MDM2 complex binding and hyper-ubiquitination in vivo, thus indicating that p53(F270A) protein hyper-ubiquitination depends upon MDM2 binding to its primary site in the BOX-I domain. Together, these data identify a novel MDM2 binding interface within the S9-S10 beta-sheet region of p53 that plays a regulatory role in modulating the rate of MDM2-dependent ubiquitination of p53 in cells.     

Role of FGF10/FGFR2b signaling during mammary gland development in the mouse embryo.

The mouse develops five pairs of mammary glands that arise during mid-gestation from five pairs of placodes of ectodermal origin. We have investigated the molecular mechanisms of mammary placode development using Lef1 as a marker for the epithelial component of the placode, and mice deficient for Fgf10 or Fgfr2b, both of which fail to develop normal mammary glands. Mammary placode induction involves two different signaling pathways, a FGF10/FGFR2b-dependent pathway for placodes 1, 2, 3 and 5 and a FGF10/FGFR2b-independent pathway for placode 4. Our results also suggest that FGF signaling is involved in the maintenance of mammary bud 4, and that Fgf10 deficient epithelium can undergo branching morphogenesis into the mammary fat pad precursor.     

Structure of the N-terminal domain of PEX1 AAA-ATPase. Characterization of a putative adaptor-binding domain

Peroxisomes are responsible for several pathways in primary metabolism, including beta-oxidation and lipid biosynthesis. PEX1 and PEX6 are hexameric AAA-type ATPases, both of which are indispensable in targeting over 50 peroxisomal resident proteins from the cytosol to the peroxisomes. Although the tandem AAA-ATPase domains in the central region of PEX1 and PEX6 are highly similar, the N-terminal sequences are unique. To better understand the distinct molecular function of these two proteins, we analyzed the unique N-terminal domain (NTD) of PEX1. Extensive computational analysis revealed weak similarity (<10% identity) of PEX1 NTD to the N-terminal domains of other membrane-related type II AAA-ATPases, such as VCP (p97) and NSF. We have determined the crystal structure of mouse PEX1 NTD at 2.05-A resolution, which clearly demonstrated that the domain belongs to the double-psi-barrel fold family found in the other AAA-ATPases. The N-domains of both VCP and NSF are structural neighbors of PEX1 NTD with a 2.7- and 2.1-A root mean square deviation of backbone atoms, respectively. Our findings suggest that the supradomain architecture, which is composed of a single N-terminal domain followed by tandem AAA domains, is a common feature of organellar membrane-associating AAA-ATPases. We propose that PEX1 functions as a protein unfoldase in peroxisomal biogenesis, using its N-terminal putative adaptor-binding domain.     

The composition of newly synthesized proteins in the endoplasmic reticulum determines the transport pathways of soybean seed storage proteins

Glycinin (11S) and beta-conglycinin (7S) are major storage proteins in soybean (Glycine max L.) seeds and accumulate in the protein storage vacuole (PSV). These proteins are synthesized in the endoplasmic reticulum (ER) and transported to the PSV by vesicles. Electron microscopic analysis of developing soybean cotyledons of the wild type and mutants with storage protein composition different from that of the wild type showed that there are two transport pathways: one is via the Golgi and the other bypasses it. Golgi-derived vesicles were observed in all lines used in this study and formed smooth dense bodies with a diameter of 0.5 to several micrometers. ER-derived protein bodies (PBs) with a diameter of 0.3-0.5 microm were observed at high frequency in the mutants containing higher amount of 11S group I subunit than the wild type, whereas they were hardly observed in the mutants lacking 11S group I subunit. These indicate that pro11S group I may affect the formation of PBs. Thus, the composition of newly synthesized proteins in the ER is important in the selection of the transport pathways.     

Assessment of splice variant-specific functions of desmocollin 1 in the skin

Desmocollin 1 (Dsc1) is part of a desmosomal cell adhesion receptor formed in terminally differentiating keratinocytes of stratified epithelia. The dsc1 gene encodes two proteins (Dsc1a and Dsc1b) that differ only with respect to their COOH-terminal cytoplasmic amino acid sequences. On the basis of in vitro experiments, it is thought that the Dsc1a variant is essential for assembly of the desmosomal plaque, a structure that connects desmosomes to the intermediate filament cytoskeleton of epithelial cells. We have generated mice that synthesize a truncated Dsc1 receptor that lacks both the Dsc1a- and Dsc1b-specific COOH-terminal domains. This mutant transmembrane receptor, which does not bind the common desmosomal plaque proteins plakoglobin and plakophilin 1, is integrated into functional desmosomes. Interestingly, our mutant mice did not show the epidermal fragility previously observed in dsc1-null mice. This suggests that neither the Dsc1a- nor the Dsc1b-specific COOH-terminal cytoplasmic domain is required for establishing and maintaining desmosomal adhesion. However, a comparison of our mutants with dsc1-null mice suggests that the Dsc1 extracellular domain is necessary to maintain structural integrity of the skin.     

Effective reduction of antigenicity of hen egg lysozyme by site-specific glycosylation

Various mutant lysozymes were constructed by genetic modification and secreted in yeast expression system to evaluate the changes in the antigenicity of hen egg lysozyme (HEL). Although Arg68, the most critical residue to antigenicity of HEL, was substituted with Gln, the binding of monoclonal antibodies (mAbs) with the mutant lysozyme did not critically reduce, remaining 60% of the binding with mAb. In contrast, glycosylated mutant lysozyme G49N whose glycine was substituted with asparagine dramatically reduced the binding with mAb. The oligomannosyl type of G49N lysozyme reduced binding with mAb to one-fifth, while the polymannosyl type of G49N lysozyme completely diminished the binding with mAb. This suggests that the site-specific glycosylation of lysozyme in the interfacial region of lysozyme-antibody complex is more effective to reduce the antigenicity than the mutation of single amino acid substitution in the interfacial region.