The Q223R polymorphism in LEPR is associated with obesity in Pacific Islanders

Various Pacific Island populations have experienced a marked increase in the prevalence of obesity in past decades. This study examined the association of a promoter polymorphism of the leptin gene (LEP), G-2548A (rs7799039), and two non-synonymous single nucleotide polymorphisms of the leptin receptor gene (LEPR), K109R (rs1137100) and Q223R (rs1137101), with body weight, body mass index (BMI) and obesity (BMI ≥ 30) in Pacific Islanders. A total of 745 Austronesian (AN)-speaking participants were analyzed after adjusting for age, gender, and population differences. The results revealed that carriers of the 223Q alleles of LEPR had significantly higher body weight (P = 0.0009) and BMI (P = 0.0022) than non-carriers (i.e., 223R homozygotes); furthermore, the 223Q carriers also had a significantly higher risk of obesity in comparison to non-carriers (P = 0.0222). The other two polymorphisms, G-2548A and K109R, were associated with neither body weight, BMI, nor obesity. The 223Q allele was widely found among the AN-speaking study subjects, thus suggesting that the LEPR Q223R polymorphism is one of the factors contributing to the high prevalence of obesity in the Pacific Island populations.     

E6AP ubiquitin ligase mediates ubiquitin‐dependent degradation of peroxiredoxin 1

E6‐associated protein (E6AP) is a cellular ubiquitin protein ligase that mediates ubiquitylation and degradation of tumor suppressor p53 in conjunction with the high‐risk human papillomavirus E6 protein. We previously reported that E6AP targets annexin A1 protein for ubiquitin‐dependent proteasomal degradation. To gain a better understanding of the physiological function of E6AP, we have been seeking to identify novel substrates of E6AP. Here, we identified peroxiredoxin 1 (Prx1) as a novel E6AP‐binding protein using a tandem affinity purification procedure coupled with mass spectrometry. Prx1 is a 25‐kDa member of the Prx family, a ubiquitous family of antioxidant peroxidases that regulate many cellular processes through intracellular oxidative signal transduction pathways. Immunoprecipitation analysis showed that E6AP binds Prx1 in vivo. Pull‐down experiments showed that E6AP binds Prx1 in vitro. Ectopic expression of E6AP enhanced the degradation of Prx1 in vivo. In vivo and in vitro ubiquitylation assays revealed that E6AP promoted polyubiquitylation of Prx1. RNAi‐mediated downregulation of endogenous E6AP increased the level of endogenous Prx1 protein. Taken together, our data suggest that E6AP mediates the ubiquitin‐dependent proteasomal degradation of Prx1. Our findings raise a possibility that E6AP may play a role in regulating Prx1‐dependent intracellular oxidative signal transduction pathways. J. Cell. Biochem. 111: 676–685, 2010. © 2010 Wiley‐Liss, Inc.     

Discrete PIH proteins function in the cytoplasmic preassembly of different subsets of axonemal dyneins

Axonemal dyneins are preassembled in the cytoplasm before being transported into cilia and flagella. Recently, PF13/KTU, a conserved protein containing a PIH (protein interacting with HSP90) domain, was identified as a protein responsible for dynein preassembly in humans and Chlamydomonas reinhardtii. This protein is involved in the preassembly of outer arm dynein and some inner arm dyneins, possibly as a cofactor of molecular chaperones. However, it is not known which factors function in the preassembly of other inner arm dyneins. Here, we analyzed a novel C. reinhardtii mutant, ida10, and found that another conserved PIH family protein, MOT48, is responsible for the formation of another subset of inner arm dyneins. A variety of organisms with motile cilia and flagella typically have three to four PIH proteins, including potential homologues of MOT48 and PF13/KTU, whereas organisms without them have no, or only one, such protein. These findings raise the possibility that multiple PIH proteins are commonly involved in the preassembly of different subsets of axonemal dyneins.     

Enzymatic production of highly soluble myricitrin glycosides using beta-galactosidase

Myricitrin, a botanical flavonol glycoside, could be a useful ingredient of functional foods, cosmetics, and medicines because of its high anti-oxidative activity. However, due to its insolubility in water, it has a limited range of use. To improve this solubility, we glycosylated myricitrin by an enzymatic transglycosylate reaction. Myricitrin was galactosylated by beta-galactosidase from Bacillus circulans using lactose as a sugar donor. The reaction product was 480 times more soluble than myricitrin. Four myricitrin galactosides were isolated from the reaction products by column chromatography, and their molecular structures were identified by using ESI-MS, 1H-NMR, 13C-NMR, 1H-1H COSY, 1H-13C HMQC and 1H-13C HMBC analysis. The solubility of these four myricitrin galactosides was more than 3.9 x 10(3) fold that of myricitrin, and each had similar anti-oxidative activity to that of myricitrin.     

Dynamic state of DNA topology is essential for genome condensation in bacteria

In bacteria, Dps is one of the critical proteins to build up a condensed nucleoid in response to the environmental stresses. In this study, we found that the expression of Dps and the nucleoid condensation was not simply correlated in Escherichia coli, and that Fis, which is an E. coli (gamma-Proteobacteria)-specific nucleoid protein, interfered with the Dps-dependent nucleoid condensation. Atomic force microscopy and Northern blot analyses indicated that the inhibitory effect of Fis was due to the repression of the expression of Topoismerase I (Topo I) and DNA gyrase. In the Deltafis strain, both topA and gyrA/B genes were found to be upregulated. Overexpression of Topo I and DNA gyrase enhanced the nucleoid condensation in the presence of Dps. DNA-topology assays using the cell extract showed that the extracts from the Deltafis and Topo I-/DNA gyrase-overexpressing strains, but not the wild-type extract, shifted the population toward relaxed forms. These results indicate that the topology of DNA is dynamically transmutable and that the topology control is important for Dps-induced nucleoid condensation.     

Comparison of cell lines for stable production of fucose-negative antibodies with enhanced ADCC

Several methods have been described to enhance antibody-dependent cellular cytotoxicity (ADCC) using different host cells that produce antibody with reduced levels of fucose on their carbohydrates. We compared the suitability of these methods for the serum-free fed-batch production of antibody for clinical trials and commercial uses. Recombinant anti-human CD20 chimeric IgG1-producing clones were established from host-cells that have been shown to produce more than 90% fucose-negative antibody. The cell lines were a FUT8 (alpha-1,6-fucosyltransferase) knockout Chinese hamster ovary (CHO) cell line, Ms704, and two Lens culinaris agglutinin (LCA)-resistant cell lines, one derived from a variant CHO line, Lec13 and the other from a rat hybridoma cell line, YB2/0. The amount of fucose-negative antibody produced by Lec13 and YB2/0 significantly decreased with the culture. The increase in fucosylation was due to remaining synthesis of GDP-fucose via de novo pathway for the CHO line and the elevation of FUT8 expression by the YB2/0 cells. In contrast, Ms704 cells stably produced fucose-negative antibody with a consistent carbohydrate structure until the end of the culture. The productivity of the Ms704 cells reached 1.76 g/L with a specific production rate (SPR) of 29 pg/cell/day for 17 days in serum-free fed-batch culture using a 1 L spinner bioreactor. Our results demonstrate that FUT8 knockout has the essential characteristics of host cells for robust manufacture of fucose-negative therapeutic antibodies with enhanced ADCC.     

Eukaryotic phylotypes in aquatic moss pillars inhabiting a freshwater lake in East Antarctica, based on 18S rRNA gene analysis

Aquatic mosses of Leptobryum species form unique tower-like pillars of vegetation termed “moss pillars” in Antarctic lakes. Moss pillars have distinct redox-affected sections: oxidative exteriors and reductive interiors. We have proposed that a “pillar” is a community and habitat of functionally interdependent organisms and may represent a mini-biosphere. Batteries of 16S rRNA genotypes, or phylotypes, of eubacteria and cyanobacteria, but no archaea, have been identified in moss pillars. However, detailed identification or phylogenetic analyses of the moss and their associated eukaryotic microbiota have not been performed. This study analyzed near-full-length 18S rRNA gene sequences obtained from two whole moss pillars. In total, 28 PCR clone libraries from two whole moss pillars were constructed, and 96 clones from each library (total 2,688 clones) were randomly selected and sequenced. Molecular phylogenetic analysis revealed that the phylotype belonging to Bryophyta, considered to be derived from moss, was closely related (99.9?%) to the 18S rRNA gene sequence from Leptobryum pyriforme. Unexpectedly, phylotypes belonging to a novel clade of fungi dominated (approximately 27–75?%) the moss pillar libraries. This suggests that fungi may contribute to carbon cycling in the moss pillar as parasites or decomposers. In addition, phylotypes related to ciliates and tardigrades were subdominant in the exterior, while the phylotype of the ameba-like, single-celled eukaryote, Cercomonas (Cercozoa), was detected only in the interior. These features were shared by both moss pillars. The 18S rRNA gene-based profiles demonstrated that redox-related factors may control distribution of some eukaryotic microbes in a whole moss pillar.