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Lodolce JP, Boone DL, Chai S, Swain RE, Dassopoulos T, Trettin S, Ma A. IL-15 receptor maintains lymphoid homeostasis by supporting lymphocyte homing and proliferation. Immunity 1998; 9:669-76. [PMID: 9846488 DOI: 10.1016/s1074-7613(00)80664-0] [Citation(s) in RCA: 1037] [Impact Index Per Article: 38.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The IL-15 receptor alpha subunit (IL-15Ralpha) mediates high-affinity binding of IL-15, a pleiotropic cytokine implicated in the development of innate immune cells. We have generated IL-15Ralpha null (IL-15Ralpha-/-) mice to understand the role of IL-15Ralpha in immune development and function. IL-15Ralpha-/- mice are markedly lymphopenic despite grossly normal T and B lymphocyte development. This lymphopenia is due to decreased proliferation and decreased homing of IL-15Ralpha-/- lymphocytes to peripheral lymph nodes. These mice are also deficient in natural killer cells, natural killer T cells, CD8+ T lymphocytes, and TCRgammadelta intraepithelial lymphocytes. In addition, memory phenotype CD8+ T cells are selectively reduced in number. Thus, IL-15Ralpha has pleiotropic roles in immune development and function, including the positive maintenance of lymphocyte homeostasis.
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Gloyd S, Chai S, Mercer MA. Antenatal syphilis in sub-Saharan Africa: missed opportunities for mortality reduction. Health Policy Plan 2001; 16:29-34. [PMID: 11238427 DOI: 10.1093/heapol/16.1.29] [Citation(s) in RCA: 116] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
PURPOSE Between 4-15% of pregnant women are believed to be infected with syphilis in sub-Saharan Africa. Active infection with syphilis in pregnant women results in foetal or infant death or disability for 50-80% of affected pregnancies, and is a major cause of adult morbidity as well. Antenatal syphilis screening is cheap and effective; however, it is often poorly implemented in countries with high syphilis risk. This study sought to estimate the missed opportunities for antenatal syphilis screening in sub-Saharan Africa. METHODS Survey data were collected from 22 ministries of health in sub-Saharan Africa, complemented by data from published sources and key informants. Informants described their country's policies and experience with antenatal syphilis screening and estimated their national syphilis screening rates. FINDINGS Seventy-three percent of women are reported by WHO to receive antenatal care in the study countries. Of women in antenatal care, 38% were estimated by survey respondents to be screened for syphilis. Costs and the organization of services were the principal reported obstacles to screening. With syphilis seroprevalence estimated at 8.3%, approximately 1 640 000 pregnant women with syphilis are undetected annually, including 1 030 000 women who attend antenatal care. DISCUSSION Syphilis testing and treatment is a cost-effective intervention that deserves much greater attention, particularly in sub-Saharan Africa and other countries where syphilis infection is high.
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Peng JM, Bera R, Chiou CY, Yu MC, Chen TC, Chen CW, Wang TR, Chiang WL, Chai SP, Wei Y, Wang H, Hung MC, Hsieh SY. Actin cytoskeleton remodeling drives epithelial-mesenchymal transition for hepatoma invasion and metastasis in mice. Hepatology 2018; 67:2226-2243. [PMID: 29171033 DOI: 10.1002/hep.29678] [Citation(s) in RCA: 104] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2017] [Revised: 11/10/2017] [Accepted: 11/19/2017] [Indexed: 01/11/2023]
Abstract
UNLABELLED High invasiveness is a hallmark of human hepatocellular carcinoma (HCC). Large tumors predict invasion and metastasis. Epithelial-mesenchymal transition (EMT) is crucial for cancer invasion and metastasis. However, the mechanisms whereby large tumors tend to undergo EMT remain unclear. We conducted a subgenome-wide screen and identified KLHL23 as an HCC invasion suppressor by inhibiting EMT. KLHL23 binds to actin and suppresses actin polymerization. KLHL23 silencing induced filopodium and lamellipodium formation. Moreover, EMT was suppressed by KLHL23 through its action on actin dynamics. Traditionally, actin cytoskeleton remodeling is downstream of EMT reprogramming. It is therefore intriguing to ask why and how KLHL23 inversely regulates EMT. Activation of actin cytoskeleton remodeling by either KLHL23 silencing or treatment with actin cytoskeleton modulators augmented cellular hypoxic responses in a cell-density-dependent manner, resulting in hypoxia-inducible factor (HIF) and Notch signals and subsequent EMT. Environmental hypoxia did not induce EMT unless actin cytoskeleton remodeling was simultaneously activated and only when cells were at high density. The resulting EMT was reversed by either adenosine 5'-triphosphate supplementation or actin polymerization inhibitors. Down-regulation of KLHL23 was associated with invasion, metastasis, and poor prognosis of HCC and pancreatic cancer. Correlations of tumor size with EMT and inverse association of expression of KLHL23 with HIF/Notch signals were further validated in patient-derived xenograft HCCs in mice. CONCLUSION Simultaneously activation of actin cytoskeleton remodeling by intrinsic (such as KLHL23 down-regulation) or microenvironment cues is crucial for cell-density-dependent and hypoxia-mediated EMT, providing a mechanistic link between large tumor size and invasion/metastasis. Our findings provide a means of developing the prevention and treatment strategies for tumor invasion and metastasis. (Hepatology 2018;67:2226-2243).
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Cegłowski P, Boitsov A, Chai S, Alonso JC. Analysis of the stabilization system of pSM19035-derived plasmid pBT233 in Bacillus subtilis. Gene 1993; 136:1-12. [PMID: 8293991 DOI: 10.1016/0378-1119(93)90441-5] [Citation(s) in RCA: 83] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The low-copy-number, 9.0-kb pSM19035-derived plasmid pBT233, is stably inherited in Bacillus subtilis. The complete nucleotide (nt) sequence of pBT233 has been determined. Analysis of the nt sequence revealed nine major open reading frames (orfs). The repS, erm1 and erm2 genes have been assigned to three of these orfs, and given the gene order, repS-orf alpha-orf beta-orf gamma-orf delta-orf epsilon-orf zeta-erm2-erm1. The organization of genes of the repS-orf gamma region resembles the organization of genes in the repE-orfI region of pAM beta 1. Messenger RNA species of molecular weights corresponding to repS, orf alpha + orf beta, orf gamma, orf delta and orf epsilon + orf zeta were detected by Northern blotting. Proteins of 23.8, 81.3, 34.4, 10.7 and 32.4 kDa correspond to Orfs beta, gamma, delta, epsilon and zeta, respectively. Bands of radioactive proteins of 25, 81, 34, 10 and 32 kDa were detected using the T7 promoter-expression system. The orf beta and orf gamma encode proteins that share homology to site-specific recombinases and type-I topoisomerases, respectively. The orfs, delta, epsilon and zeta, encode proteins with unknown activity. Deletion of a 1.5-kb segment (nt 2999-4552) with coding capacity for orf beta, orf gamma and orf delta does not seem to affect plasmid maintenance. Removal of a 3.0-kb fragment (nt 4598-7689) with coding capacity for orf epsilon and orf zeta reduced plasmid segregational stability, but deletion of a 5.2-kb DNA segment (nt 2546-7826) abolished it.(ABSTRACT TRUNCATED AT 250 WORDS)
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Wang Y, Henz ME, Gallagher NL, Chai S, Gibbs AC, Yan LZ, Stiles ME, Wishart DS, Vederas JC. Solution structure of carnobacteriocin B2 and implications for structure-activity relationships among type IIa bacteriocins from lactic acid bacteria. Biochemistry 1999; 38:15438-47. [PMID: 10569926 DOI: 10.1021/bi991351x] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Carnobacteriocin B2 (CbnB2), a type IIa bacteriocin, is a 48 residue antimicrobial peptide from the lactic acid bacterium Carnobacterium pisicola LV17B. Type IIa bacteriocins have a conserved YGNGVXC sequence near the N-terminus and usually contain a disulfide bridge. CbnB2 seemed to be unique in that its two cysteines (Cys9 and Cys14) could be isolated as free thiols [Quadri et al. (1994) J. Biol. Chem. 26, 12204-12211]. To establish the structural consequences of the presence or absence of a disulfide bridge and to investigate if the YGNGVXC sequence is a receptor-binding motif [Fleury et al. (1996) J. Biol. Chem. 271, 14421-14429], the three-dimensional solution structure of CbnB2 was determined by two-dimensional (1)H nuclear magnetic resonance (NMR) techniques. Mass spectroscopic and thiol modification experiments on CbnB2 and on model peptides, in conjunction with activity measurements, were used to verify the redox status of CbnB2. The results show that CbnB2 readily forms a disulfide bond and that this peptide has full antimicrobial activity. NMR results indicate that CbnB2 in trifluoroethanol (TFE) has a well-defined central helical structure (residues 18-39) but a disordered N terminus. Comparison of the CbnB2 structure with the refined solution structure of leucocin A (LeuA), another type IIa bacteriocin, indicates that the central helical structure is conserved between the two peptides despite differences in sequence but that the N-terminal structure (a proposed receptor binding site) is not. This is unexpected because LeuA and CbnB2 exhibit >66% sequence identity in the first 24 residues. This suggests that the N-terminus, which had been proposed [Fleury et al. (1996) J. Biol. Chem. 271, 14421-14429] to be a receptor binding site of type IIa bacteriocins, may not be directly involved and that recognition of the amphiphilic helical portion is the critical feature.
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Kwon JT, Nakajima M, Chai S, Yom YK, Kim HK, Yamazaki H, Sohn DR, Yamamoto T, Kuroiwa Y, Yokoi T. Nicotine metabolism and CYP2A6 allele frequencies in Koreans. PHARMACOGENETICS 2001; 11:317-23. [PMID: 11434509 DOI: 10.1097/00008571-200106000-00006] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
CYP2A6 is a major catalyst of nicotine metabolism to cotinine. Previously, we demonstrated that the interindividual difference in nicotine metabolism is related to a genetic polymorphism of the CYP2A6 gene in Japanese. To clarify the ethnic differences in nicotine metabolism and frequencies of CYP2A6 alleles, we studied nicotine metabolism and the CYP2A6 genotype in 209 Koreans. The cotinine/nicotine ratio of the plasma concentration 2 h after chewing one piece of nicotine gum was calculated as an index of nicotine metabolism. The genotypes of CYP2A6 gene (CYP2A6*1A, CYP2A6*1B, CYP2A6*2, CYP2A6*3, CYP2A6*4 and CYP2A6*5) were determined by polymerase chain reaction (PCR)-restriction fragment length polymorphism or allele specific (AS)-PCR. There were ethnic differences in the allele frequencies of CYP2A6*1A, CYP2A6*1B, CYP2A6*4 and CYP2A6*5 between Koreans (45.7%, 42.8%, 11.0% and 0.5%, respectively) and Japanese (42.4%, 37.5%, 20.1% and 0%, respectively, our previous data). Similar to the Japanese, no CYP2A6*2 and CYP2A6*3 alleles were found in Koreans. The homozygotes of the CYP2A6*4 allele (four subjects) were completely deficient in cotinine formation, being consistent with the data among Japanese. The heterozygotes of CYP2A6*4 tended to possess a lower metabolic ratio (CYP2A6*1A/CYP2A6*4, 4.79 +/- 3.17; CYP2A6*1B/CYP2A6*4, 7.43 +/- 4.97) than that in subjects without the allele (CYP2A6*1A/CYP2A6*1A, 7.42 +/- 6.56; CYP2A6*1A/CYP2A6*1B, 9.85 +/- 16.12; CYP2A6*1B/CYP2A6*1B, 11.33 +/- 9.33). The subjects who possess the CYP2A6*1B allele appeared to show higher capabilities of cotinine formation. It was confirmed that the interindividual difference in nicotine metabolism was closely related to the genetic polymorphism of CYP2A6. The probit plot of the metabolic ratios in Koreans (8.73 +/- 11.88) was shifted to a higher ratio than that in the Japanese (3.78 +/- 3.09). In each genotype group, the Korean subjects revealed significantly higher metabolic ratios than the Japanese subjects. The ethnic difference in cotinine formation might be due to environmental and/or diet factors as well as genetic factors.
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Valverde-Franco G, Binette JS, Li W, Wang H, Chai S, Laflamme F, Tran-Khanh N, Quenneville E, Meijers T, Poole AR, Mort JS, Buschmann MD, Henderson JE. Defects in articular cartilage metabolism and early arthritis in fibroblast growth factor receptor 3 deficient mice. Hum Mol Genet 2006; 15:1783-92. [PMID: 16624844 DOI: 10.1093/hmg/ddl100] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Fibroblast growth factor (FGF) receptor 3 has been identified as a key regulator of endochondral bone development and of post-natal bone metabolism through its action on growth plate chondrocytes and osteoblasts, respectively. It has also been shown to promote chondrogenesis and cartilage production by cultured pre-chondrogenic cells in response to FGF18. In the current studies, we show that the absence of signaling through Fgfr3 in the joints of Fgfr3(-/-) mice leads to premature cartilage degeneration and early arthritis. Degenerative changes in cartilage matrix included excessive proteolysis of aggrecan core protein and type II collagen, as measured by neo-epitope immunoreactivity. These changes were accompanied by increased expression of metalloproteinase MMP13, type X collagen, cellular hypertrophy and loss of proteoglycan at the articular surface. Using a novel micro-mechanical indentation protocol, it was shown that articular cartilage in the humeral head of 4-month-old Fgfr3(-/-) mice was less resistant to compressive force and less stiff than that of littermate controls. These results identify Fgfr3 signaling as a potential target for intervention in degenerative disorders of cartilage metabolism.
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Chai S, Lurz R, Alonso JC. The small subunit of the terminase enzyme of Bacillus subtilis bacteriophage SPP1 forms a specialized nucleoprotein complex with the packaging initiation region. J Mol Biol 1995; 252:386-98. [PMID: 7563059 DOI: 10.1006/jmbi.1995.0505] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Initiation of SPP1 DNA packaging requires the gene 1 and gene 2 products (G1P and G2P), which are different subunits of the terminase enzyme. G1P specifically recognizes the phage packaging initiation region (pac). The apparent equilibrium constant for the G1P-pac-DNA complex was estimated to be 9 nM. DNase I footprinting experiments reveal that the pac region can be subdivided into three discrete sites (pacL, pacC and pacR). G1P binds co-operatively to the non-adjacent pacL and pacR sites. Several G1P protomers bind to the target sequences which map close to the pac cleavage site (pacC site), but do not overlap with it. G1P interacts in a different fashion with the encapsidated (pacR site) and with the non-encapsidated (pacL site) end of the phage genome. G1P interaction with the intrinsically bent pacL DNA occurs only on one face of the DNA double helix. G1P binding to the pacL and in the pacR region results in a DNA loop. Electron microscopy of purified G1P shows that the protein is an oligomer in solution. G1P binding to the core region of the pacL site could facilitate the formation of a higher-order nucleoprotein structure. This specialized complex would allow the pac DNA to form a loop between binding sites brought together by interaction with G1P. The results presented here suggest that G1P could provide a tool to discriminate the first encapsidated end, which contains pacR, from the non-encapsidated pacL end.
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Chai S, Bravo A, Lüder G, Nedlin A, Trautner TA, Alonso JC. Molecular analysis of the Bacillus subtilis bacteriophage SPP1 region encompassing genes 1 to 6. The products of gene 1 and gene 2 are required for pac cleavage. J Mol Biol 1992; 224:87-102. [PMID: 1548711 DOI: 10.1016/0022-2836(92)90578-8] [Citation(s) in RCA: 61] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Packaging of Bacillus subtilis phage SPP1 DNA into viral capsids is initiated at a specific DNA site termed pac. Using an in vivo assay for pac cleavage, we show that initiation of DNA synthesis and DNA packaging are uncoupled. When the DNA products of pac cleavage were analyzed, we could detect the pac end that was destined to be packaged, but we failed to detect the other end of the cleavage reaction. SPP1 conditional lethal mutants, which map adjacent to pac, were analyzed with our assay. This revealed that the products of gene 1 and gene 2 are essential for pac cleavage. SPP1 mutants that are affected in the genes necessary for viral capsid formation (gene 41) or involved in headful cleavage (gene 6) remain proficient in pac site cleavage. Analysis of the nucleotide sequence (2.769 x 10(3) base-pairs) of the region of the genes required for pac cleavage revealed five presumptive genes. We have assigned gene 1 and gene 2 to two of these open reading frames (orf), giving the gene order gene 1-gene 2-orf 3-orf 4-orf 5. The direction of transcription of the gene 1 to orf 5 operon and the length of the mRNAs was determined. We have identified, upstream from gene 1, the major transcriptional start point (P1). Transcription originating from P1 requires a phage-encoded factor for activity. The organization of gene 1 and gene 2 of SPP1 resembles the organization of genes in the pac/cos region of different Escherichia coli double-stranded DNA phages. We propose that the conserved gene organization is representative of the packaging machinery of a primordial packaging system.
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Alonso JC, Lüder G, Stiege AC, Chai S, Weise F, Trautner TA. The complete nucleotide sequence and functional organization of Bacillus subtilis bacteriophage SPP1. Gene X 1997; 204:201-12. [PMID: 9434185 DOI: 10.1016/s0378-1119(97)00547-7] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The complete nucleotide sequence of the B. subtilis bacteriophage SPP1 is described. The genome is 44,007 bp in size and has a base composition of 43.7% dG + dC. Only 32.2 kb are essential for phage amplification under laboratory conditions. Transcription using only the 'heavy strand' is asymmetric. Eighty-one orfs organized in five early and four late operons were identified. Experiments have shown that 25 orfs are essential. Of the remaining orfs, functions could be predicted for the products of five of the orfs on the basis of comparison of the deduced amino acid sequence to known proteins. Intergenic regions include most of the 5 PE and the 4 PL promoters. Transcripts are polycistronic. Transcription from the PE promoters is mediated by host RP, whereas recognition of the PL promoters requires an additional unidentified phage-encoded product. Translation of mRNA transcribed from most of the orfs seems to be initiated independently, each from its own ribosomal binding and initiation site, although a few cases of coupled translation have been reported. The organization of SPP1 genes involved in the replication, DNA packaging and phage assembly proteins resembles the organization of genes of equivalent regions of different E. coli double-stranded DNA phages. Absence of aa sequence similarity between analogous proteins of different phages suggested that the conserved gene organization is representative of a primordial bacteriophage.
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Ceglowski P, Boitsov A, Karamyan N, Chai S, Alonso JC. Characterization of the effectors required for stable inheritance of Streptococcus pyogenes pSM19035-derived plasmids in Bacillus subtilis. MOLECULAR & GENERAL GENETICS : MGG 1993; 241:579-85. [PMID: 8264532 DOI: 10.1007/bf00279900] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The low-copy-number and broad-host-range pSM19035-derived plasmid pBT233 is stably inherited in Bacillus subtilis cells. Two distinct regions, segA and segB, enhance the segregational stability of the plasmid. Both regions function in a replicon-independent manner. The maximization of random plasmid segregation is accomplished by the recombination proficiency of the host or the presence of the pBT233 segA region. The segA region contains two open reading frames (orf) [alpha and beta]. Inactivation or deletion of orf beta results in SegA- plasmids. Better than random segregation requires an active segB region. The segB region contains two orfs (orf epsilon and orf zeta). Inactivation of either of the orfs does not lead to an increase in cell death, but orf zeta- plasmids are randomly segregated. These results suggest that pBT233 stabilization relies on a complex system involving resolution of plasmid oligomers (segA) and on the function(s) encoded by the segB region.
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Pedré X, Weise F, Chai S, Lüder G, Alonso JC. Analysis of cis and trans acting elements required for the initiation of DNA replication in the Bacillus subtilis bacteriophage SPP1. J Mol Biol 1994; 236:1324-40. [PMID: 8126723 DOI: 10.1016/0022-2836(94)90061-2] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The development of SPP1 has been studied in several B. subtilis mutants conditionally defective in initiation of DNA replication. Initiation of SPP1 replication is independent of the host DnaA (replisome organizer), DnaB, DnaC and DnaI products, but requires the DnaG (DNA primase) and the DNA gyrase. Furthermore, SPP1 replication is independent of the DnaK (heat shock) protein. The phage-encoded products required for initiation of SPP1 replication have been genetically characterized. Analysis of the nucleotide sequence (3.292 kilobases) of the region where SPP1 initiation replication mutants map, revealed five open reading frames (orf). We have assigned genes 38, 39 and 40 to three of these orfs, which have the successive order gene 38-gene 39-orf39,1-gene 40-orf41. The direction of transcription of the reading frames, the lengths of the mRNAs as well as the transcription start point, upstream of gene 38 (PE2), were identified. Proteins of 29.9, 14.6 and 46.6 kDa were anticipated from translation of gene 38, gene 39 and gene 40, respectively. The purified G38P and G39P have estimated molecular masses of 31 and 15 kDa. G38P and G39P do not share significant identity with primary protein sequences currently available in protein databases, whereas G40P shares substantial homology with a family of DNA primase-associated DNA helicases. G38P binds specifically to two discrete SPP1 DNA restriction fragments (EcoRI-4 and EcoRI-3). The G38P binding site on EcoRI-4 was localized on a 393 bp DNA segment, which lies within the coding sequence of gene 38. The putative binding site on EcoRI-3 was inferred by DNA sequence homology, it maps in a non-coding segment. G39P, which does not bind to DNA, is able to form a complex with G38P. The organization of the SPP1 genes in the gene 38 to gene 40 interval resembles that one found in the replication origin regions of different Escherichia coli double-stranded DNA phages (lambda, phi 80 and P22). We propose that the conserved gene organization is representative of the replication origin region of a primordial phage.
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Welch TJ, Chai S, Crosa JH. The overlapping angB and angG genes are encoded within the trans-acting factor region of the virulence plasmid in Vibrio anguillarum: essential role in siderophore biosynthesis. J Bacteriol 2000; 182:6762-73. [PMID: 11073922 PMCID: PMC111420 DOI: 10.1128/jb.182.23.6762-6773.2000] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Products encoded in the trans-acting factor (TAF) region are necessary for the biosynthesis of anguibactin and for maximal expression of iron transport and biosynthesis genes in the plasmid-encoded iron-scavenging system of Vibrio anguillarum. Here we identify angB, a locus located in the TAF region, which encodes products essential for anguibactin biosynthesis. We demonstrate that a 287-amino-acid polypeptide, encoded by angB and designated AngB, has an isochorismate lyase activity necessary for the synthesis of 2, 3-dihydroxybenzoic acid, an anguibactin biosynthesis intermediate. Complementation of various angB mutations provided evidence that an additional, overlapping gene exists at this locus. This second gene, designated angG, also has an essential biosynthetic function. The angG gene directs the expression of three polypeptides when overexpressed in Escherichia coli, all of which are translated in the same frame as AngB. The results of site-directed mutagenesis and in vivo phosphorylation experiments suggest that the carboxy-terminal end of AngB and the AngG polypeptide(s) function as aryl carrier proteins involved in the assembly of the anguibactin molecule. Our results also show that the regulatory functions of the TAF are encoded in a region, TAFr, which is distinct from and independent of the angB and angG genes.
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Almanza BA, Nelson D, Chai S. Obstacles to nutrition labeling in restaurants. JOURNAL OF THE AMERICAN DIETETIC ASSOCIATION 1997; 97:157-61. [PMID: 9020243 DOI: 10.1016/s0002-8223(97)00041-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE This study determined the major obstacles that foodservices face regarding nutrition labeling. DESIGN Survey questionnaire was conducted in May 1994. In addition to demographic questions, the directors were asked questions addressing willingness, current practices, and perceived obstacles related to nutrition labeling. SUBJECTS/SETTING Sixty-eight research and development directors of the largest foodservice corporations as shown in Restaurants & Institutions magazine's list of the top 400 largest foodservices (July 1993). STATISTICAL ANALYSES PERFORMED P tests were used to determine significance within a group for the number of foodservices that were currently using nutrition labeling, perceived impact of nutrition labeling on sales, and perceived responsibility to add nutrition labels. Regression analysis was used to determine the importance of factors on willingness to label. RESULTS Response rate was 45.3%. Most companies were neutral about their willingness to use nutrition labeling. Two thirds of the respondents were not currently using nutrition labels. Only one third thought that it was the foodservice's responsibility to provide such information. Several companies perceived that nutrition labeling would have a potentially negative effect on annual sales volume. Major obstacles were identified as menu or personnel related, rather than cost related. Menu-related obstacles included too many menu variations, limited space on the menu for labeling, and loss of flexibility in changing the menu. Personnel-related obstacles included difficulty in training employees to implement nutrition labeling, and not enough time for foodservice personnel to implement nutrition labeling. APPLICATIONS Numerous opportunities will be created for dietetics professionals in helping foodservices overcome these menu- or personnel-related obstacles.
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Watts SW, Chai S, Webb RC. Lead acetate-induced contraction in rabbit mesenteric artery: interaction with calcium and protein kinase C. Toxicology 1995; 99:55-65. [PMID: 7762002 DOI: 10.1016/0300-483x(94)03003-k] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Animal studies have demonstrated that low-level lead exposure produces hypertension and that lead can cause contraction of vascular smooth muscle directly. The physiological effects of lead have been associated with both stimulation and inhibition of protein kinase C (PKC). Given that vascular smooth muscle contractility is generally enhanced when protein kinase C is activated, we have tested the hypothesis that lead contracts vascular smooth muscle via stimulation of PKC. Helically-cut strips of rabbit mesenteric artery were mounted in muscle baths for measurement of isometric force development. Cumulative addition of lead acetate (10(-10)-10(-3) M) to the muscle bath produced contractions (concentration necessary to produce half-maximal response -log EC50 = 5.16 +/- 0.07). Maximal contraction to lead acetate in arteries denuded of endothelium did not differ from those in intact vessels, supporting the hypothesis that lead-induced contraction is an endothelium-independent event. Contractions to lead acetate were potentiated by the PKC activators, phorbol 12-myristate 13-acetate (TPA; 3 x 10(-7) M) and mezerein (3 x 10(-7) M), as indicated by leftward shifts in the concentration-response curve and increase in the potency of lead (-log EC50 with TPA: 6.94 +/- 0.07; -log EC50 with mezerein: 6.07 +/- 0.04). H-7 (6 x 10(-6) M), an inhibitor of PKC, decreased maximal contraction to lead approximately 65% and slightly, but insignificantly, decreased the potency of lead (-log EC50 = 4.82 +/- 0.1). The inactive phorbol ester, phorbol 12-myristate 13-acetate 4-0-methyl ether (1 x 10(-6) M), did not alter contractile responses to lead (-log EC50 = 4.92 +/- 0.09). Vascular contraction to lead partially depends on extracellular calcium as the L-type voltage-gated calcium channel antagonist, verapamil (3 x 10(-6) M), decreased lead-induced contractions by 50%. These data indicate that lead interacts with PKC in an endothelium-independent, calcium-dependent manner to cause vascular smooth muscle contraction and suggest that lead-induced increases in vascular contractility may play a role in lead-induced hypertension.
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Chai S, Welch TJ, Crosa JH. Characterization of the interaction between Fur and the iron transport promoter of the virulence plasmid in Vibrio anguillarum. J Biol Chem 1998; 273:33841-7. [PMID: 9837975 DOI: 10.1074/jbc.273.50.33841] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The expression of iron transport genes fatDCBA in Vibrio anguillarum strain 775 is negatively regulated by two iron-responsive repressors, the Fur protein and the antisense RNA, RNAalpha. Here we report the identification of the promoter for the iron transport genes and studied the interaction between the V. anguillarum Fur protein and this promoter. The iron transport promoter was localized in a region approximately 300 base pairs upstream of fatD by both primer extension and S1 mapping analysis. High activity of the promoter was measured in response to iron depletion in the wild-type strain when a promoter-lacZ fusion was examined, whereas the promoter was constitutive in the Fur-deficient strain. Gel retardation and DNase I footprint analysis showed that Fur binds specifically to two contiguous sites comprising the promoter region and the region downstream of the transcription start site. The identified Fur binding sites showed a low degree of homology to each other as well as to the consensus sequence for the Escherichia coli Fur protein. DNase I footprints pattern suggested a sequential interaction of Fur with these two sites that renders a protection in the template strand and a hypersensitivity to the nuclease in the nontemplate strand. The periodicity of the hypersensitive sites suggested that the promoter DNA undergoes a structural change upon binding to Fur, which might play a role in the repression of gene expression.
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Missich R, Weise F, Chai S, Lurz R, Pedré X, Alonso JC. The replisome organizer (G38P) of Bacillus subtilis bacteriophage SPP1 forms specialized nucleoprotein complexes with two discrete distant regions of the SPP1 genome. J Mol Biol 1997; 270:50-64. [PMID: 9231900 DOI: 10.1006/jmbi.1997.1060] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Initiation of Bacillus subtilis bacteriophage SPP1 DNA replication requires the products of genes 38, 39 and 40 (G38P, G39P and G40P). G38P specifically binds two discrete regions, which are 32.1 kb apart in a linear map of the SPP1 genome. One of these target sites, which maps at the left end of the phage genome, within gene 38, was shown to function as an origin of replication and was therefore termed left origin (oriL). The other site, which lies within a non-coding segment in the late transcribed region on the right end of the genome, was termed oriR. Both sites contain two types of repeated elements (termed Box AB and A + T-rich region). The K(app) for the G38P-oriL DNA and G38P-oriR DNA complexes was estimated to be 1 nM and 4 nM, respectively. G38P binds to the distant oriL and oriR sites cooperatively. DNase I footprinting experiments showed protection by G38P in Box AB, but not in the A + T-rich region. Electron microscopy analysis showed that G38P forms a higher-order nucleoprotein structure with the SPP1 oriL and oriR sites through protein-protein interaction. G38P binding at its cognate sites does not seem to modify the length of the DNA, but to bend it. These results suggest that G38P forms a nucleoprotein complex on the regions where the SPP1 replication origins were previously predicted.
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Chai S, Kruft V, Alonso JC. Analysis of the Bacillus subtilis bacteriophages SPP1 and SF6 gene 1 product: a protein involved in the initiation of headful packaging. Virology 1994; 202:930-9. [PMID: 8030254 DOI: 10.1006/viro.1994.1415] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Gene 1 product (G1P) of the related Bacillus subtilis bacteriophages SPP1, SF6, and rho 15 is essential for DNA maturation and packaging. A DNA segment containing gene 1 of phage SF6 or rho 15 origin was cloned and sequenced. SF6 and rho 15 G1P (both with predicted molecular mass of 16.7 kDa) share 71% identity with G1P of SPP1. The G1P of all three phages contains three conserved segments (I, II, and III). Within segments I and II helix-turn-helix DNA binding and nucleotide binding motifs were predicted. G1P of both SPP1 and SF6 origin was purified. SPP1 G1P protein (20.7 kDa), purified from cells overexpressing the cloned gene, purifies together with another polypeptide, having a molecular mass of about 13 kDa. The 13-kDa polypeptide results from a translation start signal within gene 1, and hence was termed SPP1 G1P*. G1P of both SPP1 and SF6 binds specifically to a pac-containing DNA fragment, whereas G1P*, which lacks segment I, does not. Chimeric G1P proteins were obtained by domain swapping between gene 1 of SPP1 and SF6. The results presented here suggest that the G1P DNA binding motif lies in segment I and the major determinant for G1P::G1P interaction might lie in segment II. Segment III and the extended C-terminal part of SPP1 G1P are dispensable. The G1P::G2P interacting region remains uncharacterized.
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Comparative Study |
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Abstract
VCP/p97/Cdc48, a member of the ATPases associated with diverse cellular activities (AAA) family, is necessary for the endoplasmic-reticulum-associated protein degradation (ERAD) pathway to maintain protein homeostasis. Overwhelming proteotoxic stress drove cancer cells to enhance VCP/p97/Cdc48-associated ERAD to maintain protein homeostasis for survival, demonstrating that VCP/p97/Cdc48 expression was positively correlated with cancer prognosis. More studies revealed that targeting VCP/p97/Cdc48 could be a potential target in cancer therapy. CB-5083, a novel inhibitor of VCP/p97/Cdc48, is in clinical trials as the first VCP/p97/Cdc48- inhibiting drug for cancer therapy. Here, we discuss the relationship between VCP/p97/Cdc48, ERAD, protein homeostasis and cancer therapy.
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Review |
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Fong JC, Chen CC, Liu D, Chai SP, Tu MS, Chu KY. Arachidonic acid stimulates the intrinsic activity of ubiquitous glucose transporter (GLUT1) in 3T3-L1 adipocytes by a protein kinase C-independent mechanism. Cell Signal 1996; 8:179-83. [PMID: 8736701 DOI: 10.1016/0898-6568(95)02052-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Exposure of adipocytes to arachidonic acid rapidly enhanced basal 2-deoxyglucose uptake, reaching maximal effect at approximately 8 hr. Insulin-stimulated 2-deoxyglucose uptake was not altered over the experimental period. While the short-term (2-h exposure) effect of arachidonic acid was negligibly influenced by cycloheximide, the enhancement of glucose transport by long-term (8-h) exposure to arachidonic acid was markedly decreased by the simultaneous presence of protein-synthesis inhibitors, implying that the short-term and long-term effects of arachidonic acid may involve distinct mechanisms. Immunoblot analysis revealed that 8-h but not 2-h exposure to arachidonic acid increased the content of the ubiquitous glucose transporter (GLUT1) in both total cellular and plasma membranes. The insulin-responsive glucose transporter (GLUT4), on the other hand, was not affected. Following 2-h exposure to arachidonic acid, kinetic studies indicated that the apparent Vmax of basal 2-deoxyglucose uptake was more than doubled, while the apparent Km for 2-deoxyglucose remained unchanged. Protein kinase C (PKC) depletion by pretreating cells with 4 beta-phorbol 12 beta-myristate 13 alpha-acetate (PMA) for 24 h had little influence on the subsequent enhancing effect of arachidonic acid on 2-deoxyglucose uptake. In addition, PMA was able to stimulate 2-deoxyglucose uptake in arachidonic-acid-pretreated cells with similar increments as in non-treated cells. Thus, our data seem to suggest that arachidonic acid may enhance the intrinsic activity of GLUT1 by a PKC-independent mechanism.
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Kolias TJ, Chai S, Webb RC. Potassium channel antagonists and vascular reactivity in stroke-prone spontaneously hypertensive rats. Am J Hypertens 1993; 6:528-33. [PMID: 8343237 DOI: 10.1093/ajh/6.6.528] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The goal of this study was to characterize differences in contractile responsiveness to several potassium channel antagonists in vascular smooth muscle from stroke-prone spontaneously hypertensive rats (SHRSP) and Wistar-Kyoto normotensive rats (WKY). Helically-cut strips of carotid arteries (endothelium removed) from SHRSP and WKY were mounted in muscle baths for measurement of isometric force generation. Contractile responses to tetraethylammonium (10(-4) to 3 x 10(-2) mol/L) and barium (3 x 10(-5) mol/L), blockers of the voltage-dependent and large conductance, calcium activated potassium channels, were greater in carotid arteries from SHRSP than in those from WKY. In contrast, contractile responses to the voltage-dependent potassium channel blockers 3,4-diamino-pyridine (10(-6) to 3 x 10(-3) mol/L) and sparteine (10(-6) to 3 x 10(-2) mol/L) in arteries from SHRSP did not differ from WKY values. Carotid arteries from SHRSP and WKY did not contract to apamin (10(-9) to 10(-6) mol/L), an antagonist of the small conductance, calcium activated potassium channel. Furthermore, relaxation responses to diazoxide (3 x 10(-4) mol/L), an activator of the ATP-sensitive potassium channel, and subsequent contractions to the ATP-sensitive potassium channel blocker glyburide (10(-8) to 3 x 10(-6) mol/L) in arteries from SHRSP did not differ from WKY values. Carotid artery segments from SHRSP were more sensitive to the contractile effects of elevated potassium than those from WKY. We conclude that altered activity of the large conductance, calcium activated potassium channel may play a role in the increased responsiveness observed in arteries from SHRSP.
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Comparative Study |
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Leo CP, Chai WK, Mohammad AW, Qi Y, Hoedley AFA, Chai SP. Phosphorus removal using nanofiltration membranes. WATER SCIENCE AND TECHNOLOGY : A JOURNAL OF THE INTERNATIONAL ASSOCIATION ON WATER POLLUTION RESEARCH 2011; 64:199-205. [PMID: 22053475 DOI: 10.2166/wst.2011.598] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A high concentration of phosphorus in wastewater may lead to excessive algae growth and deoxygenation of the water. In this work, nanofiltration (NF) of phosphorus-rich solutions is studied in order to investigate its potential in removing and recycling phosphorus. Wastewater samples from a pulp and paper plant were first analyzed. Commercial membranes (DK5, MPF34, NF90, NF270, NF200) were characterized and tested in permeability and phosphorus removal experiments. NF90 membranes offer the highest rejection of phosphorus; a rejection of more than 70% phosphorus was achieved for a feed containing 2.5 g/L of phosphorus at a pH <2. Additionally, NF90, NF200 and NF270 membranes show higher permeability than DK5 and MPF34 membranes. The separation performance of NF90 is slightly affected by phosphorus concentration and pressure, which may be due to concentration polarization and fouling. By adjusting the pH to 2 or adding sulfuric acid, the separation performance of NF90 was improved in removing phosphorus. However, the presence of acetic acid significantly impairs the rejection of phosphorus.
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Evaluation Study |
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Zavala F, Chai S. Protective anti-sporozoite antibodies induced by a chemically defined synthetic vaccine. Immunol Lett 1990; 25:271-4. [PMID: 1704349 DOI: 10.1016/0165-2478(90)90126-b] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Chemically defined synthetic polymers, known as multiple antigen peptide systems (MAPs) represent an effective and novel approach for engineering peptide-based vaccines. Ten different mono and diepitope MAP models, containing different arrangements and stoichiometry of functional B and/or T helper epitopes from the circumsporozoite protein of Plasmodium berghei were used to immunize mice. High titers of antibody and protective immunity against sporozoite challenge were elicited by MAPs containing T and B epitopes arranged in tandem and in equimolar amounts. These results indicate that MAPs may serve as a basis for developing subunit vaccines to induce high levels of antibodies against sporozoites.
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Chai S, Szepan U, Lüder G, Trautner TA, Alonso JC. Sequence analysis of the left end of the Bacillus subtilis bacteriophage SPP1 genome. Gene 1993; 129:41-9. [PMID: 8335259 DOI: 10.1016/0378-1119(93)90694-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The left end of the genome of Bacillus subtilis bacteriophage SPP1 is represented by EcoRI DNA fragments 12 and 1 (EcoRI-12 and EcoRI-1). A number of different deletions were identified in EcoRI-1. A detailed physical and genetic map of EcoRI-1 from wild-type (wt) phage and SPP1 deletion mutants was constructed. Genes encoding essential products involved in late and early stages of phage DNA metabolism were mapped at the left and right ends of the 8.5-kb EcoRI-1, respectively. Deletions fell within the internal 5157-bp DNA segment of EcoRI-1. The nucleotide (nt) sequence of this region and of the endpoints of two deletions, delta X and delta L, were determined. The nt sequence of the junctions in SPP1 delta X and SPP1 delta L showed that, in these deletions, a segment of DNA between short directly repeated sequences of 10 and 13 bp, located 3427 and 4562 bp apart in the wt sequence, had been eliminated. In both cases, the copy of the repeated sequence was retained in the deletion mutant, consistent with the hypothesis that the deletions originated by homologous intramolecular recombination. The corresponding region in wt phage had fifteen presumptive open reading frames (orfs) and the previously identified SPP1 early promoters (PE1). The poor growth phenotype associated with the SPP1 deletion mutants was attributed to premature transcriptional read through from promoter(s) of the early region into late operon brought into close vicinity of the late genes due to the deletion event.
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Wang H, Ji J, Yu Y, Wei X, Chai S, Liu D, Huang D, Li Q, Dong Z, Xiao X. Neonatal Overfeeding in Female Mice Predisposes the Development of Obesity in their Male Offspring via Altered Central Leptin Signalling. J Neuroendocrinol 2015; 27:600-8. [PMID: 25855235 DOI: 10.1111/jne.12281] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2014] [Revised: 03/15/2015] [Accepted: 03/31/2015] [Indexed: 02/01/2023]
Abstract
The prevalence of obesity among child-bearing women has increased significantly. The adverse consequences of maternal obesity on the descendants have been well accepted, although few studies have examined the underlying mechanisms. We investigated whether neonatal overfeeding in female mice alters metabolic phenotypes in the offspring and whether hypothalamic leptin signalling is involved. Neonatal overfeeding was induced by reducing the litter size to three pups per litter, in contrast to normal litter size of 10 pups per litter. Normal and neonatally overfed female mice were bred with normal male mice, and offspring of overfeeding mothers (OOM) and control mothers (OCM) were generated. We examined body weight, daily food intake, leptin responsiveness and the number of positive neurones for phosphorylated-signal transducer and activator of transcription 3 (pSTAT3) along with neuropeptide Y (NPY) in the arcuate nucleus of the hypothalamus (ARH) and NPY in the nucleus tractus solitarius (NTS) of the brain stem. The body weight and daily food intake of OOM were significantly higher than those of OCM. Leptin significantly reduced food intake and increased the number of pSTAT3 positive neurones in the ARH of OCM mice, whereas no significant changes in food intake and pSTAT3 neurones were found in leptin-treated OOM mice. The number of NPY neurones in the ARH and NTS of the OOM mice was significantly higher than that of OCM mice. The results of the present study indicate that the obese phenotype from mothers can be passed onto the subsequent generation, which is possibly associated with hypothalamic leptin resistance.
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