HepG2.2.15 as a model for studying cell protrusion and migration regulated by S100 proteins

Much of the difficulty in elucidating the precise function of S100 protein family has been attributed to functional redundancy and compensation by its conserved family members. In this study, we showed that seven S100 family members were almost totally undetectable in HepG2.2.15 cells, while all of them were highly expressed in its parental HepG2 cells. Re-expression of S100 proteins in HepG2.2.15 cells can partially rescue their defects in cell protrusion and migration through the regulation of cytoskeletons and adhesions. Thus, HepG2.2.15 can serve as a useful model for studying cell protrusion and migration regulated by S100 proteins.     

BSA–boronic acid conjugate as lectin mimetics

We report bovine serum albumin (BSA)–boronic acid (BA) conjugates as lectin mimetics and their glyco-capturing capacity. The BSA–BA conjugates were synthesized by amidation of carboxylic acid groups in BSA with aminophenyl boronic acid in the presence of EDC, and were characterized by Alizarin Red S (ARS) assay and SDS–PAGE gel. The BSA–BA conjugates were immobilized onto maleimide-functionalized silica beads and their sugar capturing capacity and specificity were confirmed by ARS displacement assay. Further, surface plasmon resonance (SPR) analysis of the glyco-capturing activity of the BSA–BA conjugates was conducted by immobilizing BSA–BA onto SPR gold chip. Overall, we demonstrated a BSA–BA-based lectin mimetics for glyco-capturing applications. These lectin mimetics are expected to provide an important tool for glycomics and biosensor research and applications.     

蹄蝠科的核型进化:比较染色体涂色、G带和C带分析(英文)

与其姐妹科(菊头蝠科)相比,蹄蝠科的细胞遗传学研究较少。迄今为止,仅少数蹄蝠科几个物种有高分辨率的G带核型报道,且有关该科核型进化的大多数结论都是基于常规Giemsa染色研究而得。该研究利用三叶小蹄蝠的染色体特异探针,通过比较染色体涂色、G和C显带,建立了5种蹄蝠的染色体同源性图谱,并探讨了它们同源染色体间的G和C带异同。结果表明:罗伯逊易位、臂内倒位以及异染色质的扩增可能是蹄蝠科物种核型进化的主要机制。通过对这5种蹄蝠物种及其外群物种之间的同源染色体片段的比较分析,作者推测蹄蝠科的祖先核型并不像先前认为的全由端着丝粒染色体组成,而应该含有中着丝粒染色体。     

Deficiency in a Glutamine-Specific Methyltransferase for Release Factor Causes Mouse Embryonic Lethality

Biological methylation is a fundamental enzymatic reaction for a variety of substrates in multiple cellular processes. Mammalian N6amt1 was thought to be a homologue of bacterial N⁶-adenine DNA methyltransferases, but its substrate specificity and physiological importance remain elusive. Here, we demonstrate that N6amt1 functions as a protein methyltransferase for the translation termination factor eRF1 in mammalian cells both in vitro and in vivo. Mass spectrometry analysis indicated that about 70% of the endogenous eRF1 is methylated at the glutamine residue of the conserved GGQ motif. To address the physiological significance of eRF1 methylation, we disrupted the N6amt1 gene in the mouse. Loss of N6amt1 led to early embryonic lethality. The postimplantation development of mutant embryos was impaired, resulting in degeneration around embryonic day 6.5. This is in contrast to what occurs in Escherichia coli and Saccharomyces cerevisiae, which can survive without the N6amt1 homologues. Thus, N6amt1 is the first glutamine-specific protein methyltransferase characterized in vivo in mammals and methylation of eRF1 by N6amt1 might be essential for the viability of early embryos.Nucleic acids, proteins, carbohydrates, and lipids, as well as a body of small molecules, are subject to methylation in a wide variety of biological contexts (3). The majority of methylation reactions are catalyzed by S-adenosylmethionine (AdoMet)-dependent methyltransferases (MTases). These enzymes ubiquitously exist in species from all three domains of life.Methylation of DNA occurs on one of two bases: cytosine or adenine (19). In prokaryotes, adenine methylation is as widespread as cytosine methylation. In contrast, eukaryotic genomes are devoid of adenine methylation or this type of methylation is too rare to be detected (23, 26). Intriguingly, two putative N⁶-adenine DNA MTases, named N6amt1 and N6amt2, are encoded in the mouse and human genomes. In addition to the conserved AdoMet-binding signature motif GXGXG and other sequence elements, they possess the NPPY motif characteristic of the N⁶-adenine or N⁴-cytosine DNA MTases in bacteria (6, 14). N6amt1 was thus proposed as an AdoMet-dependent DNA MTase, although no evidence had been provided that N6amt1 could methylate DNA (23).No functional clue for N6amt1 existed until two groups independently identified Escherichia coli HemK, distantly related to N6amt1, as a protein MTase for polypeptide release factors RF1 and RF2 (8, 17). The HemK gene was initially discovered in a genetic screen for heme biosynthesis mutants (18), although subsequent studies revealed no direct involvement in heme metabolism. The presence of an NPPY motif, thought to be restricted to members of the adenine and cytosine amino methyltransferases, led to the suggestion that HemK could be an AdoMet-dependent DNA MTase (2). However, a series of genetic and biochemical experiments finally revealed that HemK methylates the side-chain amide group of a glutamine residue in the universally conserved tripeptide motif GGQ of the two release factors in E. coli (8, 17). Methylation of the release factors ensures efficient translation termination and release of newly synthesized peptide from the ribosome (16). Similarly, the yeast HemK homologue, YDR140w (Mtq2p), was confirmed to methylate the eukaryotic release factor eRF1 on a corresponding glutamine residue (9, 22). More recently, the human homologue N6amt1 (HemK2) was reported to methylate release factor 1 (eRF1) in vitro (5).We initially sought to characterize the function of N6amt1 as a potential DNA adenine MTase. Interestingly, the human N6amt1 gene is located on chromosome 21q21.3, a critical region for Down syndrome (1, 20). In this study, we report the identification of murine N6amt1 as a glutamine-specific MTase of eRF1 both in vitro and in vivo. Mammalian eRF1, the only mammalian release factor, is indeed methylated at the glutamine residue of the GGQ motif. Inactivation of the N6amt1 gene by targeted disruption led to embryonic lethality in the mouse. These data confirm that N6amt1 functions as a protein MTase in mammals and indicate that modulation of the eRF1 activity by N6amt1-mediated glutamine methylation might be essential for embryo viability.     

Identification and characterization of adipose triglyceride lipase (ATGL) gene in birds

Adipose triglyceride lipase (ATGL) is a triglyceride hydrolysis lipase and is generally related to lipid metabolism in animals. The ATGL gene was well studied in mammals, however very less was known in birds that differed significantly with mammals for lipid metabolism. In this study, cloning, mRNA real time and association analysis was performed to characterize the ATGL gene in birds. Results showed that the obtained ATGL gene cDNA of parrot, quail, duck were 1,651 bp (NCBI accession number: GQ221784), 1,557 bp (NCBI accession number: GQ221783) and 1,440 bp each, encoded 481-, 482- and 279-amino acid (AA) peptide, respectively. The parrot ATGL (pATGL) gene was found to predominantly express in breast muscle and leg muscle, and very higher ATGL mRNA level was also found in heart, abdominal fat and subcutaneous fat. The quail ATGL (qATGL) gene was also predominantly expressed in breast muscle and leg muscle, and then to a much lesser degree in heart. The duck ATGL (dATGL) gene was found to predominantly express in subcutaneous fat and abdominal fat, quite higher ATGL mRNA was also found in heart, spleen, breast muscle and leg muscle. Blast analyses indicated the high homology of ATGL and its patatin region, and moreover, and the active serine hydrolase motif (“GASAG” for “GXSXG”) and the glycine rich motif (“GCGFLG” for “GXGXXG”) were completely conservative among 14 species. Association analyses showed that c.950+24C>A, c.950+45C>G, c.950+73G>A, c.950+83C>T and c.950+128delA of chicken ATGL gene (cATGL) were all significantly or highly significantly with cingulated fat width (CFW) (P < 0.05 or P < 0.01), and c.777−26C>A, c.950+45C>G, c.950+73G>A and c.950+118C>T were all significantly or highly significantly with pH value of breast muscle (BMPH) (P < 0.05).     

Novel rhamnolipid biosurfactants produced by a polycyclic aromatic hydrocarbon-degrading bacterium Pseudomonas aeruginosa strain NY3

A novel rhamnolipid biosurfactant-producing and Polycyclic Aromatic Hydrocarbon (PAH)-degrading bacterium Pseudomonas aeruginosa strain NY3 was isolated from petroleum-contaminated soil samples. Strain NY3 was characterized by its extraordinary capacity to produce structurally diverse rhamnolipids. A total of 25 rhamnolipid components and 37 different parent molecular ions, representing various metal ion adducts (Na⁺, 2Na⁺ and K⁺), were detected by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Among these compounds are ten new rhamnolipids. In addition to its biosurfactant production, strain NY3 was shown to be capable of efficient degradation of PAHs as well as synergistic improvement in the degradation of high molecular weight PAHs by its biosurfactant. These findings have added novel members to the rhamnolipid group and expanded current knowledge regarding the diversity and productive capability of rhamnolipid biosurfactants from a single specific strain with variation of only one carbon source. Additionally, this paper lays the foundation for improvement in the yield of NY3BS and study of the degradation pathway(s) of PAHs in P. aeruginosa strain NY3.     

Discrimination of geographical origin and adulteration of radix astragali using fourier transform infrared spectroscopy and chemometric methods

Introduction – Radix Astragali, one of most widely used and important traditional Chinese medicines, is cultivated in different geographical regions. Because of varying growing conditions, the qualities of Radix Astragali vary, which can give rise to differences in clinical therapy. Detecting adulteration is a routine requirement in pharmaceutical practice. Objective – To develop a simple and accurate approach to discriminate the geographical origin and potential adulteration of Radix Astragali, derived from the root of Astragalus membranaceus (Fischer) Bunge var. mongholicus (Bunge) Hsiao, using Fourier transform infrared (FT‐IR) spectroscopy and chemometric methods. Methodology – To obtain characteristic IR spectra for accurate discrimination, a one‐solvent extraction method was utilised following a novel evaluation method for selecting appropriate solvents. Samples of Radix Astragali from different geographical origins were discriminated using FT‐IR spectroscopy and discriminant partial least squares (DPLS) methods. FT‐IR spectroscopy combined with Mahalanobis distance was employed to detect adulteration of Radix Astragali. Results – In comparison with other solvents, butanone was more effective at extracting samples. Radix Astragali samples were accurately assigned to their corresponding geographical origins by using FT‐IR spectroscopy and DPLS method. Most adulterated samples were detected accurately by application of FT‐IR spectroscopy combined with Mahalanobis distance. Conclusion – FT‐IR spectroscopy combined with chemometric method was developed and demonstrated to be a useful tool to discriminate geographical origin and adulteration of Radix Astragali. Copyright © 2010 John Wiley & Sons, Ltd.     

Targeted quantitative analysis of superoxide dismutase 1 in cisplatin-sensitive and cisplatin-resistant human ovarian cancer cells

Protein quantification in a complex protein mixture presents a daunting task in biochemical analysis. Antibody-based immunoassays are traditional methods for protein quantification. However, there are issues associated with accuracy and specificity in these assays, especially when the changes are small (e.g., <2-fold). With recent developments in mass spectrometry, monitoring a selected peptide, thus protein, in a complex biological sample has become possible. In this study, we demonstrate a simple mass spectrometry-based method for selective measurement of a moderately low abundant protein, superoxide dismutase 1 (SOD1), in cisplatin-sensitive and cisplatin-resistant human ovarian cancer cells. Selected-reaction-monitoring (SRM) technology was employed to specifically analyze the target peptides in a pair of human ovarian cancer cell lines: 2008/2008-C13*5.25 (cisplatin-sensitive/cisplatin-resistant, respectively). The observed 1.47-fold higher expression in the resistant cell line is consistent with findings by other approaches. This robust liquid chromatography/mass spectrometry (LC/MS) method provides a powerful tool for targeted proteomic verification and/or validation studies.