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Chen YQ, Kraut J, Blakley RL, Callender R. Determination by Raman spectroscopy of the pKa of N5 of dihydrofolate bound to dihydrofolate reductase: mechanistic implications. Biochemistry 1994; 33:7021-6. [PMID: 8003467 DOI: 10.1021/bi00189a001] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Dihydrofolate reductase (DHFR) catalyzes the reduction of dihydrofolate (H2folate) to tetrahydrofolate by NADPH, and this requires that the pteridine ring be protonated at N5. A long-standing puzzle has been how, at physiological pH, the enzyme can protonate N5 in view of its solution pKa of 2.6 and the fact that the only proton-donating group in the pterdine binding site, Asp-27, hydrogen bonds not to N5 but to the 2-amino group and N3 of the pterin ring. We have determined the pKa of N5 of dihydrofolate in the Escherichia coli DHFR/NADP+/H2folate ternary complex by Raman difference spectroscopy and found that the value is 6.5. In contrast, the pKa of N5 is less than 4.0 in either the binary complex, the ternary complex with an analogue of NADPH (H2NADPH), or the Asp27 to serine mutant DHFR (D27S) ternary complex with NADP+. Thus, one need not invoke proton donation from Asp-27 to N5 via a series of bound water molecules and/or pteridine-ring substituents. We propose instead that the N5 protonated form of H2folate is stabilized directly at the active site in the DHFR/NADPH/H2folate complex by specific interactions that form only in the ternary complex, involving perhaps a bound water molecule, the carboxamide moiety of the coenzyme, and/or the local electrostatic field of the enzyme molecule, to which an important contribution may be made by Asp-27.
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Chang CH, Chen YQ. Decays of the Bc meson. PHYSICAL REVIEW. D, PARTICLES AND FIELDS 1994; 49:3399-3411. [PMID: 10017335 DOI: 10.1103/physrevd.49.3399] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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253
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Clyman RI, Tannenbaum J, Chen YQ, Cooper D, Yurchenco PD, Kramer RH, Waleh NS. Ductus arteriosus smooth muscle cell migration on collagen: dependence on laminin and its receptors. J Cell Sci 1994; 107 ( Pt 4):1007-18. [PMID: 8056826 DOI: 10.1242/jcs.107.4.1007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
During permanent closure of the ductus arteriosus, smooth muscle cells migrate through the extracellular matrix (ECM) to form intimal mounds that occlude the vessel's lumen. Smooth muscle cells (SMC) migrate over surfaces coated with collagen in vitro. During the migration SMC also synthesize fibronectin (FN) and laminin (LN). Antibodies against FN and LN inhibit migration on collagen by 30% and 67%, respectively. Because of the apparent importance of LN in migration, we examined how SMC interact with LN and LN fragments (P1, E8, P1′, E1′, E3, E4, and G). Ductus SMC adhere to high concentrations of LN and two fragments of the molecule: P1 and E8. They use a unique set of integrin receptors to bind to LN (alpha 1 beta 1, alpha 6 beta 1 and alpha v beta 3), to P1 (alpha 1 beta 1, alpha v beta 3), and to E8 (alpha 6 beta 1, alpha v beta 3). The alpha v beta 3 integrin binds to the P1 fragment of LN in an RGD peptide-dependent manner, and to the E8 fragment in an RGD-independent manner; the RGD site on the P1 fragment probably is not available to the cell in intact LN. Antibodies against beta 1 integrins completely inhibit SMC adhesion to LN; antibodies against the alpha v beta 3 integrin do not block SMC adhesion to LN, but do prevent cell spreading. LN is also capable of interfering with SMC adhesion to other ECM components. The antiadhesive effect of LN is located in the E1′ domain. Both exogenous and endogenous LN increase SMC motility on collagen I. The locomotion-promoting activity of LN resides in the E1′ antiadhesive domain, and not in its adhesive (P1, E8) domains. LN causes a decrease in the number of focal contacts on collagen I. This might enable SMC to alter their mobility as they move through the extracellular matrix to occlude the ductus arteriosus lumen.
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Chen YQ, Duniec ZM, Liu B, Hagmann W, Gao X, Shimoji K, Marnett LJ, Johnson CR, Honn KV. Endogenous 12(S)-HETE production by tumor cells and its role in metastasis. Cancer Res 1994; 54:1574-9. [PMID: 7511046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
12(S)-Hydroxyeicosatetraenoic acid [12(S)-HETE] is the 12-lipoxygenase metabolite of arachidonic acid. Previously, we have demonstrated that exogenous 12(S)-HETE can activate protein kinase C, increase cell surface expression of integrins, enhance adhesion, induce endothelial cell retraction, and increase experimental metastasis of tumor cells. Because of these prominent effects of exogenous 12(S)-HETE on tumor cell metastatic potential, it is important to determine whether there is endogenous 12(S)-HETE production by tumor cells. In the present study, mRNAs from human, rat, and mouse platelets as well as human colon carcinoma (Clone A), rat Walker carcinoma (W256), and mouse melanoma (B16a) and lung carcinoma (3LL) were reverse transcribed and amplified by polymerase chain reaction with platelet 12-lipoxygenase specific primers. Identity of the polymerase chain reaction fragments was confirmed by sequencing. 12-Lipoxygenase protein was detected by Western blotting. Tumor cell-derived 12-HETE was determined by reverse phase-high performance liquid chromatography analysis. In addition, the effect of endogenous 12(S)-HETE on tumor cells was studied by using a platelet-type 12-lipoxygenase selective inhibitor (N-benzyl-N-hydroxy-5-phenylpentanamide). Our results suggest that some tumor cells express platelet-type 12-lipoxygenase mRNA, protein and metabolize arachidonic acid to 12(S)-HETE and that endogenous 12(S)-HETE, like the exogenous 12(S)-HETE, may play an important role in tumor cell adhesion to matrix in vitro and lung colonization in vivo.
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MESH Headings
- 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid
- Amino Acid Sequence
- Animals
- Arachidonate 12-Lipoxygenase/analysis
- Arachidonate 12-Lipoxygenase/physiology
- Base Sequence
- Blotting, Western
- Carcinoma, Squamous Cell/enzymology
- Carcinoma, Squamous Cell/metabolism
- Carcinoma, Squamous Cell/pathology
- Cell Adhesion/physiology
- Chromatography, High Pressure Liquid/methods
- Extracellular Matrix/physiology
- Humans
- Hydroxyeicosatetraenoic Acids/biosynthesis
- Hydroxyeicosatetraenoic Acids/physiology
- Lipoxygenase Inhibitors
- Lung Neoplasms/secondary
- Male
- Mice
- Mice, Inbred C57BL
- Molecular Sequence Data
- Neoplasm Metastasis/physiopathology
- Neoplasms, Experimental/enzymology
- Neoplasms, Experimental/metabolism
- Neoplasms, Experimental/pathology
- Polymerase Chain Reaction/methods
- RNA-Directed DNA Polymerase/metabolism
- Rats
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Chen YQ, Mauviel A, Ryynänen J, Sollberg S, Uitto J. Type VII collagen gene expression by human skin fibroblasts and keratinocytes in culture: influence of donor age and cytokine responses. J Invest Dermatol 1994; 102:205-9. [PMID: 8106749 DOI: 10.1111/1523-1747.ep12371763] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Type VII collagen is the predominant, if not the exclusive, component of the anchoring fibrils. In this study, we have examined the expression of the type VII collagen gene in human skin fibroblasts and keratinocytes in culture by Northern analyses and immunocytochemistry. Type VII collagen gene expression was greatly enhanced in all cell strains studied after stimulation by transforming growth factor-beta (TGF-beta). However, no definitive correlation between the donor age and the magnitude of TGF-beta response could be made. In contrast, the basal expression of the type VII collagen gene was shown to decrease in an age-dependent manner in fibroblasts. The pro-inflammatory cytokines interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha) were shown to elevate type VII collagen mRNA levels in a dose-dependent manner. This response was inversely related to the donor age of the cell cultures. The attenuated response of cells from older individuals to TNF-alpha and IL-1 beta was specific for type VII collagen gene expression, because, in the same experiments, collagenase gene expression was strongly elevated by the two cytokines. Our data suggest that type VII collagen gene expression is subject to modulation by the cytokine network, which may play a role in controlling anchoring fibril assembly in normal skin and in pathologic conditions characterized by altered deposition of type VII collagen.
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Chen YQ, Miao JZ, Zhang XZ. [Determination of antibody of Borrelia burgdorferi in the serum of patients with sarcoidosis and its significance]. ZHONGHUA NEI KE ZA ZHI 1994; 33:15-7. [PMID: 8045180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The level of antibody of Borrelia Burgdorferi in the serum of 40 patient, 23 with sarcoidosis and 17 without sarcoidosis was determined by using ELISA method. Antibody of BB was positive in the serum of 18 patients with sarcoidosis (78.3%). It is possible that sarcoidosis might be a disease of autoimmune abnormality and antibody of BB in the serum an auto-antibody resulting from the stimuli of certain unknown antigens. Cross reactivity may be present between the serological tests for sarcoidosis and those for rheumatic disease, tuberculosis, tumour and Lyme disease. But another case might be that antigen of BB is a mixture. Different antibodies of different disease react with different component of antigen of BB. Therefore, antibody of BB can not be considered as a specific test in the diagnosis of sarcoidosis.
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Clyman RI, Peters KG, Chen YQ, Escobedo J, Williams LT, Ives HE, Wilson E. Phospholipase C gamma activation, phosphotidylinositol hydrolysis, and calcium mobilization are not required for FGF receptor-mediated chemotaxis. CELL ADHESION AND COMMUNICATION 1994; 1:333-42. [PMID: 8081884 DOI: 10.3109/15419069409097264] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Basic fibroblast growth factor (FGF) is a potent angiogenic factor that stimulates several cell types to migrate along a chemotactic gradient. Most chemoattractant receptors appear to share a common mechanism that involves activation of phospholipase C (PLC), hydrolysis of phosphotidylinositol, and mobilization of intracellular calcium. We transfected two different cell lines with either human FGF receptor-1 cDNA or chimeric FGF receptor cDNA. Ligand stimulation induced chemotaxis, activation of PLC gamma, phosphotidylinositol hydrolysis, and calcium mobilization in both wild-type receptor cell lines. No such response was elicited in control cells. Mutation of the two fibroblast growth factor receptors at residue 766, replacing tyrosine with phenylalanine, made the receptors incapable of associating with and activating PLC gamma following ligand stimulation. These mutant receptors also failed to mediate phosphotidylinositol hydrolysis and calcium mobilization. However, cells transfected with the mutant fibroblast growth factor receptors were as chemotactically responsive to the appropriate ligand as were cells transfected with the wild-type receptors. These findings demonstrate that the ability of the fibroblast growth factor receptor to promote chemotaxis is not dependent on increased activation of PLC gamma, increased hydrolysis of phosphotidylinositol, or increased global mobilization of calcium.
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258
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Cannizzaro LA, Chen YQ, Rafi MA, Wenger DA. Regional mapping of the human galactocerebrosidase gene (GALC) to 14q31 by in situ hybridization. CYTOGENETICS AND CELL GENETICS 1994; 66:244-5. [PMID: 8162701 DOI: 10.1159/000133703] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The cDNA for human galactocerebrosidase (GALC) has recently been cloned and expressed. A portion of this cDNA was used for in situ hybridization, and the region of strongest signal corresponded to human chromosome region 14q31. This agrees with recent linkage studies that localized Krabbe disease (globoid cell leukodystrophy) to the same region. This information will be useful in future studies for mapping this gene in animal models of GALC deficiency.
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259
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Chen YQ. Perturbative QCD predictions for the fragmentation functions of the P- wave mesons with two heavy quarks. PHYSICAL REVIEW. D, PARTICLES AND FIELDS 1993; 48:5181-5189. [PMID: 10016177 DOI: 10.1103/physrevd.48.5181] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Chen YQ, Rafi MA, de Gala G, Wenger DA. Cloning and expression of cDNA encoding human galactocerebrosidase, the enzyme deficient in globoid cell leukodystrophy. Hum Mol Genet 1993; 2:1841-5. [PMID: 8281145 DOI: 10.1093/hmg/2.11.1841] [Citation(s) in RCA: 117] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Globoid cell leukodystrophy (Krabbe disease) is an autosomal recessive disorder resulting from the deficiency of galactocerebrosidase (GALC) activity. GALC is responsible for the lysosomal catabolism of galactosylceramide, a major lipid in myelin, kidney and epithelial cells of small intestine and colon. We describe the molecular cloning of human GALC cDNA and its expression in COS-1 cells. Degenerate PCR primers, derived from N-terminal amino acid sequence from the 51 kDa band from human brain, were used to amplify cat testes RNA, and the resulting product was used to screen human testes and brain libraries. Two overlapping clones contained the total protein coding region, while additional clones and PCR amplification were needed to obtain the complete 3' end of the cDNA. The 3795 bp obtained include 47 bp 5' to the initiation start site, 2007 bp of open reading frame (coding for 669 amino acids), and 1741 bp of 3' untranslated sequence. Modification of the sequence surrounding the initiation codon to one more favorable for expression, resulted in a 6-fold increase in GALC activity in transfected COS-1 cells. The isolation of this clone will permit investigations into the causes for GALC deficiency in humans and available animal models, development of more accurate tests for patient and carrier identification, and evaluation of methods for effectively treating GALC deficiency, initially using the animal models.
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262
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Tang DG, Chen YQ, Newman PJ, Shi L, Gao X, Diglio CA, Honn KV. Identification of PECAM-1 in solid tumor cells and its potential involvement in tumor cell adhesion to endothelium. J Biol Chem 1993; 268:22883-94. [PMID: 8226797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
PECAM-1 (CD31/EndoCAM) is an adhesion molecule in the immunoglobulin supergene family that is expressed on endothelial cells, platelets, and some hematopoietic lineage cells. In this paper, using several polyclonal and monoclonal antibodies against PECAM-1, we identified PECAM-1 molecules on human, rat, and murine solid tumor cell lines. Immunocytochemical labeling and flow cytometric analysis using either polyclonal, monoclonal, or Fab portion of the antibodies against PECAM-1 detected a distinct distribution on tumor cell surface. Immunoblotting revealed proteins ranging from 120 to 130 kDa in tumor cells derived from different species. Immunoprecipitation and subcellular fractionation studies indicated that PECAM-1 is constitutively expressed on the surface of human tumor cells (i.e. colon adenocarcinoma). The specificity of a major polyclonal anti-PECAM-1 used in the current study (i.e. SEW-3) was confirmed by the preabsorption studies. PECAM-1 molecules on tumor cells appear to bear terminal carbohydrate moieties (i.e. sialic acid residues) different from those on platelets, since neuraminidase treatment of tumor cells, unlike platelets, did not result in a mobility shift. Polymerase chain reaction (PCR) analysis of genomic DNA derived from tumor cell lines of different species revealed the presence of PECAM-1 gene in the genome. The mRNAs of PECAM-1 in tumor cells were detected by reverse transcription-PCR followed by Southern hybridization. Screening of more than 20 human, rat, and murine solid tumor cell lines indicated that PECAM-1 is widely expressed, although the level of expression varies considerably among different cell lines. The expression of PECAM-1 message in tumor cells was confirmed by Northern blotting. DNA sequencing of the PCR fragment revealed that human tumor cell PECAM-1 matches 100% to the human endothelial cell counterpart. Finally, it was demonstrated that tumor cell PECAM-1 is involved in mediating tumor cell adhesion to endothelium, as evidenced by the ability of anti-PECAM-1 antibodies to decrease the adhesion of unstimulated tumor cells to microvascular endothelial cells.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antibodies
- Antigens, Differentiation, Myelomonocytic/analysis
- Antigens, Differentiation, Myelomonocytic/biosynthesis
- Antigens, Differentiation, Myelomonocytic/metabolism
- Base Sequence
- Cell Adhesion
- Cell Adhesion Molecules/analysis
- Cell Adhesion Molecules/metabolism
- Cell Line
- Cells, Cultured
- DNA Primers
- DNA, Neoplasm/isolation & purification
- DNA, Neoplasm/metabolism
- Endothelium, Vascular/physiology
- Fluorescent Antibody Technique
- Humans
- Immunohistochemistry
- Mice
- Molecular Sequence Data
- Oligonucleotides, Antisense
- Platelet Endothelial Cell Adhesion Molecule-1
- Polymerase Chain Reaction
- Rats
- Tumor Cells, Cultured/cytology
- Tumor Cells, Cultured/metabolism
- Tumor Cells, Cultured/physiology
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263
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Chen YQ, Wenger DA. Galactocerebrosidase from human urine: purification and partial characterization. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1170:53-61. [PMID: 8399327 DOI: 10.1016/0005-2760(93)90175-9] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Galactocerebrosidase (GALC, EC 3.2.1.46) was purified from human urine by a series of hydrophobic affinity column chromatography steps. The activity was enriched 176,000-fold from concentrated urine by only four columns, including octyl Sepharose, hydroxylapatite, butyl Sepharose and ethyl-agarose. The overall recovery was about 20% but only low amounts were obtained due to its low abundance. The estimated final specific activities of several batches were between 1 and 2 mmol/h per mg protein. The final purified fractions were essentially free of other lysosomal enzyme activities. The most pure fractions showed a series of bands between 50 and 53 kDa on sodium dodecylsulfate-polyacrylamide gel electrophoresis which were determined to have identical N-terminal amino acid sequence. In addition, gel filtration of partially purified GALC after disassociation showed one peak of activity estimated to have a molecular mass near 50 kDa. GALC was also purified from human brain and human placenta using the same methods demonstrating the usefulness of this procedure in obtaining GALC from solid human tissues. In addition to the bands migrating near 50 kDa from urine, there were also bands at 80 kDa and 30 kDa in some preparations. By N-terminal sequencing and the use of antipeptide antibodies, the 80 kDa band was demonstrated to have the same N-terminal amino acids as the 50-53 kDa bands. The 30 kDa band had a unique sequence. The relationship between the different molecular weight species remains to be determined. The purification of GALC and the securing of amino acid sequence information will aid in the cloning of the GALC gene. This enzyme is deficient in human patients with Krabbe disease and several animal species.
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Wang MH, Chen YQ, Gercken J, Ernst M, Böhle A, Flad HD, Ulmer AJ. Specific activation of human peripheral blood gamma/delta + lymphocytes by sonicated antigens of Mycobacterium tuberculosis: role in vitro in killing human bladder carcinoma cell lines. Scand J Immunol 1993; 38:239-46. [PMID: 8356400 DOI: 10.1111/j.1365-3083.1993.tb01720.x] [Citation(s) in RCA: 19] [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
Tumour regression induced in cancer patients by local instillation of Bacillus Calmette-Guérin (BCG) into the bladder has been considered to be mainly mediated by activated cellular immunity and inflammatory reactions. In the present study we investigated the cytotoxicity of T cells bearing gamma/delta T-cell receptors (gamma/delta + cells) against bladder carcinoma cells in vitro. Long-term cultured gamma/delta + T-cell lines from peripheral blood lymphocytes of healthy donors were established by stimulation with sonicated cell wall-associated antigens of Mycobacterium tuberculosis (SMA). These gamma/delta + T cells lack the natural killer (NK) markers CD16 and CD56, as determined by flow cytometry. The SMA-specific gamma/delta + T cells exhibited profound cytotoxicity against two NK-resistant bladder tumour cell lines as well as against NK-sensitive tumour cells in a non-major histocompatibility complex-restricted manner. The pattern of tumour cells killed by gamma/delta + T cells differed significantly from those of NK cells and lymphokine-activated killer LAK cells. Furthermore, we tested the effects of recombinant human cytokines, including interleukin (IL)-1, IL-2, IL-4, IL-6, interferon (IFN)-gamma and tumour necrosis factor (TNF), on gamma/delta + T-cell-mediated cytotoxicity. It was shown that the addition of recombinant TNF in co-incubation could augment gamma/delta + T-cell-mediated killing of two bladder tumour cell lines, but not of cells of the erythroleukaemia cell line K562. Based on these results it was concluded that mycobacterial antigens could specifically activate resting gamma/delta + T cells. The cytotoxicity of gamma/delta + T cells against bladder tumour cells and its selective enhancement by TNF may be an important mechanism involved in bladder tumour regression induced by intravesical instillation of BCG.
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265
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Goldberg JM, Zheng J, Deng H, Chen YQ, Callender R, Kirsch JF. Structure of the complex between pyridoxal 5'-phosphate and the tyrosine 225 to phenylalanine mutant of Escherichia coli aspartate aminotransferase determined by isotope-edited classical Raman difference spectroscopy. Biochemistry 1993; 32:8092-7. [PMID: 8347609 DOI: 10.1021/bi00083a006] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The azomethine (Schiff base) linkage between the epsilon-amino group of active-site lysine 258 and the carbonyl moiety of enzyme-bound pyridoxal 5'-phosphate (PLP) normally exhibits absorbance maxima at ca. 360 (high-pH form) or ca. 430 nm (low-pH form). However, the absorbance maximum is shifted from 358 to 386 nm, a value which is similar to that of free PLP (lambda max = 388 nm), in a mutant form of Escherichia coli aspartate aminotransferase (AATase) in which tyrosine 225, which normally donates a hydrogen bond to the phenolate function of PLP, has been replaced with phenylalanine (Y225F). This spectral shift suggested that PLP binds to Y225F as the free aldehyde. The following evidence from isotope-edited classical Raman spectroscopy proves conclusively that the near-UV spectrum is anomalous and that PLP is bound to Y225F as a Schiff base: (1) A strong cofactor peak at 1630 cm-1 in the holoenzyme-minus-apoenzyme difference spectrum of the unprotonated form of Y225F is red-shifted by 18 cm-1 in enzyme labeled with 15N at lysine 258 and other positions. (2) This isotope-induced red shift is similar to that observed in the unprotonated form of the model Schiff base, PLP-valine. (3) The Raman spectrum of Y225F is unchanged in H(2)18O, while peaks at ca. 1670 cm-1 in the spectrum of free PLP or in that of a mutant of AATase in which Lys-258 is replaced with Ala, are red-shifted by ca. 30 cm-1 in H(2)18O.(ABSTRACT TRUNCATED AT 250 WORDS)
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Zheng J, Chen YQ, Callender R. A study of the binding of NADP coenzymes to dihydrofolate reductase by raman difference spectroscopy. EUROPEAN JOURNAL OF BIOCHEMISTRY 1993; 215:9-16. [PMID: 8344289 DOI: 10.1111/j.1432-1033.1993.tb18001.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
We report here the Raman spectra of NADPH, NADP+, 3-acetylpyridine adenine dinucleotide (AcPdADP+), NADH and a fragment of these molecules, 2'-phospho-adenosine-5'-diphosphoribose (Ado2'p5'ppRib), bound to Escherichia coli dihydrofolate reductase (DHFR). The positions that are observed for the bound adenosine 'triplet' bands are consistent with a protein binding pocket for this group which is quite hydrophobic in nature. No binding effect is observed on Raman bands associated with the nicotinamide group of NADP+ as a binary complex with DHFR, suggesting very loose, if any, binding of this group. In contrast, changes in the Raman spectrum of the nicotinamide group of NADP+ bound to an inhibitor (trimethoprim) ternary complex of DHFR are clearly observed which indicate substantial binding interaction. The carboxamide group of bound NADPH (and NADH) adopts the trans conformation. A 35-cm-1 upshift is observed in the rocking motion of the carboxamide -NH2 group of NADPH, and a 5-cm-1 upward shift is seen in the C=O stretch mode of AcPdADP+ upon binding to the enzyme-trimethoprim complex. These results suggest that the -NH2 group of the carboxamide moiety is more tightly hydrogen bonded in the protein binding pocket than in solution while that of the C=O group is less tightly hydrogen bonded; these hydrogen bonds would appear to be responsible for holding the nicotinamide headgroup in place properly for catalysis. We have compared this with the results obtained previously in other protein complexes, and interpret the observed shifts in these bands as a measure of the hydrogen bonding enthalpy of the -NH2 and C=O groups with their protein environments. Perhaps surprisingly, the magnitude of the hydrogen bonding enthalpy takes on a limited number of discrete values over five protein complexes rather than over a continuous range. The effect that this has on the catalytic properties of DHFR and the other NAD dehydrogenases that we have studied to date, particularly their stereochemistry, is discussed. A small downward shift is observed for the P = O stretch of the 2'-phosphate moiety of NADP. This indicates that the 2'-phosphate moiety binds to DHFR in the dianionic form. Furthermore, the local enthalpic interaction that the 2'-phosphate group has with protein is stronger than its interaction with water.
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Gao X, Honn KV, Grignon D, Sakr W, Chen YQ. Frequent loss of expression and loss of heterozygosity of the putative tumor suppressor gene DCC in prostatic carcinomas. Cancer Res 1993; 53:2723-7. [PMID: 8504411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The putative tumor suppressor gene DCC has been shown to be frequently lost or expressed at low levels in colorectal, gastric, pancreatic, and esophageal carcinomas. In the present study, the DCC gene and its mRNA expression in human and rat prostatic carcinoma cells as well as in prostatic carcinoma tissues were examined by reverse transcriptase-polymerase chain reaction and polymerase chain reaction-loss of heterozygosity. The DCC gene was present and expressed in normal prostatic cells. However, its expression was decreased or undetectable in all prostatic carcinoma cells from either humans (4 cell lines) or rats (5 cell lines). In patients, 12 of 14 cases (86%) showed reduced DCC expression and 5 of 11 informative cases (45%) showed loss of heterozygosity at the DCC locus. These results demonstrate that loss of DCC expression and loss of heterozygosity at the DCC locus are a frequent feature of prostatic carcinoma cells.
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268
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Tang DG, Chen YQ, Diglio CA, Honn KV. Protein kinase C-dependent effects of 12(S)-HETE on endothelial cell vitronectin receptor and fibronectin receptor. J Cell Biol 1993; 121:689-704. [PMID: 7683691 PMCID: PMC2119558 DOI: 10.1083/jcb.121.3.689] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
12(S)-HETE, a lipoxygenase metabolite of arachidonic acid induced a nondestructive and reversible endothelial cell (EC) retraction. 12(S)-HETE induced EC retraction was inhibited by protein kinase C inhibitors calphostin C and staurosporine but not by the protein kinase A inhibitor H8. The role of EC integrins alpha v beta 3 and alpha 5 beta 1 in 12(S)-HETE induced EC retraction was investigated. In confluent EC cultures, alpha v beta 3 is localized to focal adhesions at both the cell body and cell-cell borders and is colocalized with vinculin-containing focal adhesions. In contrast, alpha 5 beta 1 is primarily enriched at the cell-cell borders, demonstrating codistribution with cell cortical microfilaments and extracellular fibronectin. Both receptors were functional in mediating cell-cell or cell-matrix interactions based on the observations that specific antibodies inhibited EC adhesion to intact subendothelial matrix and disrupted the monolayer integrity. 12(S)-HETE induced a multistep, temporally defined redistribution of the alpha v beta 3-containing focal adhesions, leading to an eventual decrease in alpha v beta 3 plaques in the retracted ECs. This effect of 12(S)-HETE was inhibited by calphostin C but not by H8. The alterations of alpha v beta 3-containing focal adhesions preceded the development of EC retraction. 12(S)-HETE also enhanced EC alpha v beta 3 surface expression as revealed by immunofluorescence, flow cytometry, and digitized image analysis. 12(S)-HETE-induced alpha v beta 3 rearrangement (i.e., decreased focal adhesion localization and enhanced surface expression) did not result from altered mRNA transcription (as revealed by semi-quantitative RT-PCR analysis) or protein translation (as revealed by Western blotting). In contrast to its effect on alpha v beta 3, 12(S)-HETE did not demonstrate a temporally related, well-defined effect on the distribution pattern and the surface expression of alpha 5 beta 1, although the cell-cell border staining pattern of alpha 5 beta 1 was disrupted due to EC retraction. It is concluded that 12(S)-HETE-induced decrease of alpha v beta 3 localization to focal adhesions may contribute to the development of EC retraction and that 12(S)-HETE induced increase in alpha v beta 3 surface expression may promote adhesion of inflammatory leukocytes as well as tumor cells to endothelium.
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MESH Headings
- 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid
- Alkaloids/pharmacology
- Animals
- Aorta
- Base Sequence
- Cell Adhesion/drug effects
- Cells, Cultured/drug effects
- Endothelium, Vascular/drug effects
- Hydroxyeicosatetraenoic Acids/antagonists & inhibitors
- Hydroxyeicosatetraenoic Acids/pharmacology
- Mice
- Microcirculation/drug effects
- Molecular Sequence Data
- Naphthalenes
- Polycyclic Compounds/pharmacology
- Protein Kinase C/antagonists & inhibitors
- Rats
- Rats, Sprague-Dawley
- Receptors, Cytoadhesin/drug effects
- Receptors, Cytoadhesin/metabolism
- Receptors, Fibronectin/drug effects
- Receptors, Fibronectin/metabolism
- Receptors, Vitronectin
- Staurosporine
- Vinculin
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269
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Tang DG, Grossi IM, Chen YQ, Diglio CA, Honn KV. 12(S)-HETE promotes tumor-cell adhesion by increasing surface expression of alpha V beta 3 integrins on endothelial cells. Int J Cancer 1993; 54:102-11. [PMID: 8478136 DOI: 10.1002/ijc.2910540117] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The present work was undertaken to investigate the regulatory role of 12(S)-HETE, a lipoxygenase metabolite of arachidonic acid, in the surface expression of alpha v beta 3 integrin receptors in endothelial cells (rat aortic endothelial cells, or RAEC). Several monoclonal and polyclonal antibodies localized alpha v beta 3 in focal adhesions in both subconfluent and post-confluent RAEC. RAEC alpha v beta 3 integrins were further characterized by immunoblotting and immunoprecipitation. 12(S)-HETE, but not 12(R)-HETE or other lipoxygenase-derived hydroxy fatty acids, induced a dose-dependent increase in alpha v beta 3 surface expression in RAEC, which was antagonized by prostacyclin or its analog iloprost as well as by 13-HODE, a 15-lipoxygenase product of linoleic acid. 12(S)-HETE promoted RAEC adhesion to vitronectin, an effect inhibited by antibodies against alpha v beta 3. 12(S)-HETE also promoted tumor-cell (W256 carcinosarcoma) adhesion to vitronectin, which was inhibited by various antibodies against alpha IIb beta 3 but not by an antibody against alpha v. W256 adhesion to 12(S)-HETE-treated RAEC demonstrated a significant increase, which was inhibited by anti-alpha v, -beta 3, or -alpha v beta 3 antibodies and by 13-HODE. Western blotting, immunoprecipitation and reverse transcription-polymerase chain reaction indicated that W256 carcinosarcoma cells expressed alpha IIb beta 3 integrins but not alpha v beta 3. The results suggest that the lipoxygenase metabolites [i.e., 12(S)-HETE and 13-HODE] play a significant role in modulating tumor-cell interactions with endothelium by enhancing endothelial cell integrin (e.g., alpha v beta 3) expression.
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270
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Mauviel A, Chen YQ, Kähäri VM, Ledo I, Wu M, Rudnicka L, Uitto J. Human recombinant interleukin-1 beta up-regulates elastin gene expression in dermal fibroblasts. Evidence for transcriptional regulation in vitro and in vivo. J Biol Chem 1993; 268:6520-4. [PMID: 8454621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The effects of human recombinant interleukin (IL)-1 beta on elastin gene expression were studied in human skin fibroblast cultures by Northern hybridization and transient transfection experiments. Incubation of the cells with IL-1 beta elevated the elastin mRNA steady-state levels by approximately 3- to 4-fold. A similar increase was noted at the protein level, when estimated by indirect immunofluorescence of cultured cells. This effect was independent of the on-going protein synthesis, as tested by incubation with cycloheximide. Transient transfections of the dermal fibroblasts with a human elastin promoter/chloramphenicol acetyltransferase (CAT) reporter gene construct suggested transcriptional regulation, since the CAT activity in cells incubated with IL-1 beta was similarly increased approximately 3-fold. Enhancement of the human elastin promoter activity by IL-1 beta was also noted in fibroblast cultures established from the skin and lungs of transgenic mice which have integrated the human promoter/CAT construct into their genome and express it in a tissue-specific manner. Furthermore, subcutaneous injection of IL-1 beta to the mice resulted in a approximately 4-fold elevation of the CAT activity in the skin after a 30-h incubation, as compared to the CAT activity in the skin of control animals. Collectively, these data indicate that IL-1 beta up-regulates elastin gene expression in fibroblast cultures as well as in the skin in vivo, and the activation occurs at the transcriptional level.
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271
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Wang MH, Chen YQ, Flad HD, Baer HH, Feist W, Ulmer AJ. Inhibition of interleukin-6 release and T-cell proliferation by synthetic mirror pseudo cord factor analogues in human peripheral blood mononuclear cells. FEMS IMMUNOLOGY AND MEDICAL MICROBIOLOGY 1993; 6:53-61. [PMID: 8472015 DOI: 10.1111/j.1574-695x.1993.tb00303.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The effects of synthetic alkyl ((alkyl 6-deoxy-a-D-gluco-heptopyranosyluronate) 6-deoxy-a-D-gluco-heptopyranoside) uronates, a novel type of mirror pseudo cord factor, on the in vitro modulation of interleukin-6 production and T-cell proliferation in human peripheral blood mononuclear cells, were investigated. Synthetic mirror pseudo cord factors with alkyl chains ranging from C16 to C18 have very weak interleukin-6-inducing capacities and lack mitogenic activities for T-cell proliferation. However, they could inhibit IL-6 release induced by sonicated Bacillus Calmette-Guérin (S-BCG), bacterial endotoxin, and phytohaemagglutinin in a dose-dependent manner. Inhibition was observed not only with mononuclear cells but also with purified monocytes. Furthermore, these synthetic compounds could suppress T-lymphocyte proliferation stimulated by sonicated Mycobacterium tuberculosis H37Rv (S-H37Rv) antigens, S-BCG antigens, as well as by recombinant 65 kDa mycobacterial heat-shock protein. In contrast, these compounds failed to inhibit the phytohaemagglutinin-induced T-cell proliferation. We conclude that the inhibition of cytokine release and T-cell proliferation by synthetic mirror pseudo cord factors was due to direct blocking of the function and/or activity of monocytes or antigen-presenting cells.
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272
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Tan EM, Rouda S, Hoffren J, Chen YQ, Uitto J, Li K. Extracellular matrix gene expression by human keratinocytes and fibroblasts from donors of varying ages. TRANSACTIONS OF THE ASSOCIATION OF AMERICAN PHYSICIANS 1993; 106:168-78. [PMID: 8036740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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273
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Chen YQ, Zhang YP. [Analysis of clinical effect and experimental study of 13 herbs anti-cough-dyspnea decoction in the treatment of chronic bronchitis]. ZHONGGUO ZHONG XI YI JIE HE ZA ZHI ZHONGGUO ZHONGXIYI JIEHE ZAZHI = CHINESE JOURNAL OF INTEGRATED TRADITIONAL AND WESTERN MEDICINE 1993; 13:27-9, 5. [PMID: 8499731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
In treating chronic bronchitis, the effect of 13 Herbs Anti-Cough-Dyspnea decoction was better than that of other traditional prescriptions such as Ephedria-almond decoction etc. The effective rate of this decoction in relieving cough, sputum, bronchial spasm and eliminating wheezing sound were 98.6%, 98.32%, 91.52% and 85.35% respectively. The total effective rate was 98%. The animal experiment revealed that the decoction was given to isolated trachea after medication for 30 min, the effective rate in easing bronchial spasm was 99.1 +/- 30.2%, which was two times than that of other prescriptions.
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274
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Chen YQ, Kuang YP. Erratum: Improved QCD-motivated heavy-quark potentials with explicit Lambda MS-bar dependence. PHYSICAL REVIEW. D, PARTICLES AND FIELDS 1993; 47:350. [PMID: 10015410 DOI: 10.1103/physrevd.47.350] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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275
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Kähäri VM, Chen YQ, Bashir MM, Rosenbloom J, Uitto J. Tumor necrosis factor-alpha down-regulates human elastin gene expression. Evidence for the role of AP-1 in the suppression of promoter activity. J Biol Chem 1992; 267:26134-41. [PMID: 1281483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Cytokine modulation of elastin gene expression was examined by assay of elastin mRNA abundance and by transient transfections of cultured human skin fibroblasts and rat aortic smooth muscle cells with elastin promoter/reporter gene (chloramphenicol acetyltransferase, CAT) constructs. Incubation of cells with human recombinant tumor necrosis factor-alpha (TNF-alpha) markedly suppressed the elastin mRNA levels in a time- and dose-dependent manner by up to 91%. TNF-alpha also suppressed the expression of the elastin promoter/CAT construct by up to 70% in transiently transfected cells, indicating regulation at the transcriptional level. This suppression was temporally preceded by rapid and transient up-regulation of c-jun and c-fos genes. The down-regulatory effect of TNF-alpha on elastin promoter activity was abolished by co-transfections with a synthetic double-stranded AP-1 oligomer. Furthermore, co-transfection of the elastin promoter construct with c-jun and c-fos expression plasmids resulted in a marked decrease in the promoter activity. Elucidation of the cis-regulatory elements in the elastin promoter by 5' deletion construct analysis implicated a region -290 to -198 containing one AP-1 binding site. The functional role of this AP-1 site was further tested by gel retardation assays which indicated formation of a DNA-protein complex specific for TNF-alpha treated cells. This complex could be partially dissociated by a competing oligomer containing the consensus AP-1 binding site. These observations suggest that the inhibitory effects of TNF-alpha on elastin gene expression involve the transcription factor AP-1. Interferon-gamma also suppressed the elastin gene expression at the mRNA level by approximately 52%, but it had no effect on the elastin promoter activity, suggesting post-transcriptional mechanisms. These results indicate that mediators released from inflammatory cells can modulate elastin gene expression, and such modulation may play a role in diseases characterized by altered accumulation of elastic fibers in tissues.
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