Glutathione Oxidase from Bovine Skim Milk Membranes: Its Copurification with γ-Glutamyltransferase

Two hundred thirteen cytochrome P450 (P450) genes were collected from bacteria and expressed based on an Escherichia coli expression system to test their hydroxylation ability to testosterone. Twenty-four P450s stereoselectively monohydroxylated testosterone at the 2α-, 2β-, 6β-, 7β-, 11β-, 12β-, 15β-, 16α-, and 17-positions (17-hydroxylation yields 17-ketoproduct). The hydroxylation site usage of the P450s is not the same as that of human P450s, while the 2α-, 2β-, 6β-, 11β-, 15β-, 16α-, and 17-hydroxylation are reactions common to both human and bacterial P450s. Most of the testosterone hydroxylation catalyzed by bacterial P450s is on the β face.     

LPA4/p2y9/GPR23 mediates rho-dependent morphological changes in a rat neuronal cell line

Lysophosphatidic acid (LPA) is a potent lipid mediator that evokes a variety of biological responses in many cell types via its specific G protein-coupled receptors. In particular, LPA affects cell morphology, cell survival, and cell cycle progression in neuronal cells. Recently, we identified p2y(9)/GPR23 as a novel fourth LPA receptor, LPA(4) (Noguchi, K., Ishii, S., and Shimizu, T. (2003) J. Biol. Chem. 278, 25600-25606). To assess the functions of LPA(4) in neuronal cells, we used rat neuroblastoma B103 cells that lack endogenous responses to LPA. In B103 cells stably expressing LPA(4), we observed G(q/11)-dependent calcium mobilization, but LPA did not affect adenylyl cyclase activity. In LPA(4) transfectants, LPA induced dramatic morphological changes, i.e. neurite retraction, cell aggregation, and cadherin-dependent cell adhesion, which involved Rho-mediated signaling pathways. Thus, our results demonstrated that LPA(4) as well as LPA(1) couple to G(q/11) and G(12/13), whereas LPA(4) differs from LPA(1) in that it does not couple to G(i/o). Through neurite retraction and cell aggregation, LPA(4) may play a role in neuronal development such as neurogenesis and neuronal migration.     

Short-term pretreatment with low-dose hydrogen peroxide enhances the efficacy of bone marrow cells for therapeutic angiogenesis

Therapeutic angiogenesis can be induced by the implantation of bone marrow cells (BMCs). Hydrogen peroxide (H(2)O(2)) has been shown to increase VEGF expression and to be involved in angiogenesis. We tested the hypothesis that pretreatment with H(2)O(2) enhances the efficacy of BMCs for neovascularization. H(2)O(2) pretreatment was done by incubating mouse BMCs in 5 microM H(2)O(2) for 30 min, followed by washing twice with PBS. The H(2)O(2)-pretreated and untreated BMCs were then studied in vitro and in vivo. RT-PCR analysis showed that expression of VEGF and Flk-1 mRNA was significantly higher in H(2)O(2)-pretreated BMCs than in untreated BMCs after 12 and 24 h of culture (P<0.01). Pretreatment with H(2)O(2) also effectively enhanced the VEGF production and endothelial differentiation from BMCs after 1 and 7 days of culture (P<0.05). To estimate the angiogenic potency in vivo, H(2)O(2)-pretreated or untreated BMCs were intramuscularly implanted into the ischemic hindlimbs of mice. After 14 days of treatment, many of the H(2)O(2)-pretreated BMCs were viable, showed endothelial differentiation, and were incorporated in microvessels. Conversely, the survival and incorporation of the untreated BMCs were relatively poor. Microvessel density and blood flow in the ischemic hindlimbs were significantly greater in the mice implanted with H(2)O(2)-pretreated BMCs than in those implanted with untreated BMCs (P<0.05). These results show that the short-term pretreatment of BMCs with low-dose H(2)O(2) is a novel, simple, and feasible method of enhancing their angiogenic potency.     

ɛ-Poly-<Emphasis Type="SmallCaps">l</Emphasis>-lysine producer, <Emphasis Type="Italic">Streptomyces albulus</Emphasis>, has feedback-inhibition resistant aspartokinase

Streptomyces albulus NBRC14147 produces ɛ-poly-l-lysine (ɛ-PL), which is an amino acid homopolymer antibiotic. Despite the commercial importance of ɛ-PL, limited information is available regarding its biosynthesis; the l-lysine molecule is directly utilized for ɛ-PL biosynthesis. In most bacteria, l-lysine is biosynthesized by an aspartate pathway. Aspartokinase (Ask), which is the first enzyme in this pathway, is subject to complex regulation such as through feedback inhibition by the end-product amino acids such as l-lysine and/or l-threonine. S. albulus NBRC14147 can produce a large amount of ɛ-PL (1–3 g/l). We therefore suspected that Ask(s) of S. albulus could be resistant to feedback inhibition to provide sufficient l-lysine for ɛ-PL biosynthesis. To address this hypothesis, in this study, we cloned the ask gene from S. albulus and investigated the feedback inhibition of its gene product. As predicted, we revealed the feedback resistance of the Ask; more than 20% relative activity of Ask was detected in the assay mixture even with extremely high concentrations of l-lysine and l-threonine (100 mM each). We further constructed a mutated ask gene for which the gene product Ask (M68V) is almost fully resistant to feedback inhibition. The homologous expression of Ask (M68V) further demonstrated the increase in ɛ-PL productivity.     

ε-Poly-l-Lysine Peptide Chain Length Regulated by the Linkers Connecting the Transmembrane Domains of ε-Poly-l-Lysine Synthetase

ε-Poly-l-lysine (ε-PL), consisting of 25 to 35 l-lysine residues with linkages between the α-carboxyl groups and ε-amino groups, is produced by Streptomyces albulus NBRC14147. ε-PL synthetase (Pls) is a membrane protein with six transmembrane domains (TM1 to TM6) as well as both an adenylation domain and a thiolation domain, characteristic of the nonribosomal peptide synthetases. Pls directly generates ε-PL chain length diversity (25- to 35-mer), but the processes that control the chain length of ε-PL during the polymerization reaction are still not fully understood. Here, we report on the identification of Pls amino acid residues involved in the regulation of the ε-PL chain length. From approximately 12,000 variants generated by random mutagenesis, we found 8 Pls variants that produced shorter chains of ε-PL. These variants have one or more mutations in two linker regions connecting the TM1 and TM2 domains and the TM3 and TM4 domains. In the Pls catalytic mechanism, the growing chain of ε-PL is not tethered to the enzyme, implying that the enzyme must hold the growing chain until the polymerization reaction is complete. Our findings reveal that the linker regions are important contributors to grasp the growing chain of ε-PL.     

Expression and effects of epidermal growth factor on human periodontal ligament cells

Repair of damaged periodontal ligament (PDL) tissue is an essential challenge in tooth preservation. Various researchers have attempted to develop efficient therapies for healing and regenerating PDL tissue based on tissue engineering methods focused on targeting signaling molecules in PDL stem cells and other mesenchymal stem cells. In this context, we investigated the expression of epidermal growth factor (EGF) in normal and surgically wounded PDL tissues and its effect on chemotaxis and expression of osteoinductive and angiogenic factors in human PDL cells (HPDLCs). EGF as well as EGF receptor (EGFR) expression was observed in HPDLCs and entire PDL tissue. In a PDL tissue-injured model of rat, EGF and IL-1β were found to be upregulated in a perilesional pattern. Interleukin-1β induced EGF expression in HPDLCs but not EGFR. It also increased transforming growth factor-α (TGF-α) and heparin-binding EGF-like growth factor (HB-EGF) expression. Transwell assays demonstrated the chemotactic activity of EGF on HPDLCs. In addition, EGF treatment significantly induced secretion of bone morphogenetic protein 2 and vascular endothelial growth factor, and gene expression of interleukin-8 (IL-8), and early growth response-1 and -2 (EGR-1/2). Human umbilical vein endothelial cells developed well-formed tube networks when cultured with the supernatant of EGF-treated HPDLCs. These results indicated that EGF upregulated under inflammatory conditions plays roles in the repair of wounded PDL tissue, suggesting its function as a prospective agent to allow the healing and regeneration of this tissue.     

Optimizing high-resolution melting analysis for the detection of mutations of GPR30/GPER-1 in breast cancer

G protein-coupled receptor 30/G protein estrogen receptor-1 (GPR30/GPER-1) is a novel membrane receptor for estrogen whose mRNA is expressed at high levels in estrogen-dependent cells such as breast cancer cell lines. However, mutations in GRP30 related to diseases remain unreported. To detect unknown mutations in the GPR30 open reading frame (ORF) quickly, the experimental conditions for high-resolution melting (HRM) analysis were examined for PCR primers, Taq polymerases, saturation DNA binding dyes, Mg(2+) concentration, and normalized temperatures. Nine known SNPs and 13 artificial point mutations within the GPR30 ORF, as well as single nucleotide variants in DNA extracted from subjects with breast cancers were tested under the optimal experimental conditions. The combination of Expand High Fidelity(PLUS) and SYTO9 in the presence of 2.0 mM MgCl(2) produced the best separation in melting curves of mutations in all regions of the GPR30 ORF. Under these experimental conditions, the mutations were clearly detected in both heterozygotes and homozygotes. HRM analysis of GPR30 using genomic DNA from subjects with breast cancers showed a novel single nucleotide variant, 111C>T in GPR30 and 4 known SNPs. The experimental conditions determined in this study for HRM analysis are useful for high throughput assays to detect unknown mutations within the GPR30 ORF.     

IA mutant functional antigen-presenting cell lines

We describe a protocol for the selection of mutant cells with an altered pattern of Ia antigenic determinants and antigen-presenting properties from a homogeneous population of functional antigen-presenting cells (APC). The APC line used in this work was obtained by fusing lipopolysaccharide-stimulated B cells from (BALB/c x A/J)F1 donors with cells from the M12.4.1 BALB/c B lymphoma cell line. The resulting hybridomas, including TA3, retained the potent antigen-presenting activity of the parental B lymphoma line and expressed Ia antigens and immune response gene-determined antigen-presenting properties of the A/J type. Mutants of TA3 were obtained by subjecting the cells to negative immunoselection with one monoclonal anti-(alpha) 1-Ak antibody and complement followed by positive immunoselection via electronic cell sorting with a second monoclonal alpha I-Ak or alpha I-Ek antibody. Two types of mutants were obtained. One, A8, appeared to have undergone a fairly limited alteration, since it lost only some of the I-Ak antigenic determinants; the second type appeared to have lost the entire I-Ak molecule but to have retained the I-E molecule. Functional studies with the A8 mutant demonstrated that the loss of a limited number of I-Ak determinants correlated with the loss of a specific I-Ak-encoded restriction element, since A8 failed to present a specific antigen, hen egg lysozyme (HEL), to a HEL-specific I-Ak-restricted T cell hybridoma but retained some capacity to present a second antigen, poly(Glu60Ala30Tyr10) (GAT), to a GAT-specific I-Ak-restricted T cell hybridoma. These results indicate that Ia antigens are the products of immune response gene loci. The availability of such mutants should allow an examination of the relationship between the structure of an Ia molecule and the antigens with which it is co-recognized by T cells.