22 results on '"Hwang, D. M."'
Search Results
2. A Catalogue of Genes in the Cardiovascular System as Identified by Expressed Sequence Tags
- Author
-
Liew, C. C., Hwang, D. M., Fung, Y. W., Laurenssen, C., Cukerman, E., Tsui, S., and Lee, C. Y.
- Published
- 1994
3. Lentivirus IL-10 Gene Therapy Down-Regulates IL-17 and Attenuates Mouse Orthotopic Lung Allograft Rejection
- Author
-
Hirayama, S., Sato, M., Loisel-Meyer, S., Matsuda, Y., Oishi, H., Guan, Z., Saito, T., Yeung, J., Cypel, M., Hwang, D. M., Medin, J. A., Liu, M., and Keshavjee, S.
- Published
- 2013
- Full Text
- View/download PDF
4. Microstructural analysis of the Ge/Pd(Zn) ohmic contact to p-InP
- Author
-
Park, Moon-Ho, Wang, L. C., and Hwang, D. M.
- Published
- 1996
- Full Text
- View/download PDF
5. Self-Arrangement of Molybdenum Particles Into Cubes
- Author
-
Edelstein, A. S., Chow, G. M., Altman, E. I., Colton, R. J., and Hwang, D. M.
- Published
- 1991
6. GaAs Clusters in the Quantum Size Regime: Growth on High Surface Area Silica by Molecular Beam Epitaxy
- Author
-
Sandroff, C. J., Harbison, J. P., Ramesh, R., Andrejco, M. J., Hegde, M. S., Hwang, D. M., Chang, C. C., and Vogel, E. M.
- Published
- 1989
7. Direct Observation of Structural Defects in Laser-Deposited Superconducting Y-Ba-Cu-O Thin Films
- Author
-
Ramesh, R., Hwang, D. M., Venkatesan, T., Ravi, T. S., Nazar, L., Inam, A., Wu, X. D., Dutta, B., Thomas, G., Marshall, A. F., and Geballe, T. H.
- Published
- 1990
8. Diagnostic patterns of non-small-cell lung cancer at Princess Margaret Cancer Centre.
- Author
-
Nadjafi, M., Sung, M. R., Santos, G. D. C., Le, L. W., Hwang, D. M., Tsao, M. S., and Leighl, N. B.
- Subjects
NON-small-cell lung carcinoma ,BRONCHOSCOPY ,LUNG cancer ,PATHOLOGIC neovascularization ,TUMOR classification ,PRINCESSES ,DRILL core analysis - Abstract
Background Accurate classification of lung cancer subtypes has become critical in tailoring lung cancer treatment. Our study aimed to evaluate changes in diagnostic testing and pathologic subtyping of advanced non-small-cell lung cancer (nsclc) over time at a major cancer centre. Methods In a review of patients diagnosed with advanced nsclc at Princess Margaret Cancer Centre between 2007-2009 and 2013-2015, diagnostic method, sample type and site, pathologic subtype, and use of immunohistochemistry (ihc) staining and molecular testing were abstracted. Results The review identified 238 patients in 2007-2009 and 283 patients in 2013-2015. Over time, the proportion of patients diagnosed with adenocarcinoma increased to 73.1% from 60.9%, and diagnoses of nsclc not otherwise specified (nos) decreased to 6.4% from 18.9%, p < 0.0001. Use of diagnostic bronchoscopy decreased (26.9% vs. 18.4%), and mediastinal sampling procedures, including endobronchial ultrasonography, increased (9.2% vs. 20.5%, p = 0.0001). Use of ihc increased over time to 76.3% from 41.6% (p < 0.0001). Larger surgical or core biopsy samples and those for which ihc was performed were more likely to undergo biomarker testing (both p < 0.01). Conclusions Customizing treatment based on pathologic subtype and molecular genotype has become key in treating patients with advanced lung cancer. Greater accuracy of pathology diagnosis is being achieved, including through the routine use of ihc. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
9. Superconducting thin films on Si: HTSCs meet VLSI
- Author
-
Inam, A., Wu, X. D., Ventekatesan, T., Hwang, D. M., Chang, C. C., Ramesh, R., Miura, S., Matsubara, S., Miyasaka, Y., and Shohata, N.
- Subjects
Semiconductor industry ,Thin-film circuits -- Production management ,High temperature superconductors -- Production management ,Semiconductor industry -- Production management - Abstract
Superconducting Thin Films on Si: HTSCs Meet VLSI The integration of high temperature superconductors (HTSCs) with conventional semiconductor-based technology would have important consequences for micro-eletronics, with the promise of high […]
- Published
- 1990
10. Improving molecular testing and personalized medicine in non-small-cell lung cancer in Ontario.
- Author
-
Lim, C., Sekhon, H. S., Cutz, J. C., Hwang, D. M., Kamel-Reid, S., Carter, R. F., da Cunha Santos, G., Waddell, T., Binnie, M., Patel, M., Paul, N., Chung, T., Brade, A., El-Maraghi, R., Sit, C., Tsao, M. S., and Leighl, N. B.
- Subjects
NON-small-cell lung carcinoma ,CANCER treatment ,BIOPSY ,MOLECULAR biology ,CANCER diagnosis - Abstract
Background Although molecular testing has become standard in managing advanced nonsquamous non-small-cell lung cancer (NSCLC), most patients undergo minimally invasive procedures, and the diagnostic tumour specimens available for testing are usually limited. A knowledge translation initiative to educate diagnostic specialists about sampling techniques and laboratory processes was undertaken to improve the uptake and application of molecular testing in advanced lung cancer. Methods A multidisciplinary panel of physician experts including pathologists, respirologists, interventional thoracic radiologists, thoracic surgeons, medical oncologists, and radiation oncologists developed a specialty-specific education program, adapting international clinical guidelines to the local Ontario context. Expert recommendations from the program are reported here. Results Panel experts agreed that specialists procuring samples for lung cancer diagnosis should choose biopsy techniques that maximize tumour cellularity, and that conservation strategies to maximize tissue for molecular testing should be used in tissue processing. The timeliness of molecular reporting can be improved by pathologist-initiated reflex testing upon confirmation of nonsquamous NSCLC and by prompt transportation of specimens to designated molecular diagnostic centres. To coordinate timely molecular testing and optimal treatment, collaboration and communication between all clinicians involved in diagnosing patients with advanced lung cancer are mandatory. Conclusions Knowledge transfer to diagnostic lung cancer specialists could potentially improve molecular testing and treatment for advanced lung cancer patients. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
11. cis-9,trans-11-Conjugated linoleic acid down-regulates phorbol ester-induced NF- B activation and subsequent COX-2 expression in hairless mouse skin by targeting I B kinase and PI3K-Akt
- Author
-
Hwang, D.-M., primary, Kundu, J. K., additional, Shin, J.-W., additional, Lee, J.-C., additional, Lee, H. J., additional, and Surh, Y.-J., additional
- Published
- 2006
- Full Text
- View/download PDF
12. Ex VivoPerfusion Treatment of Infection in Human Donor Lungs
- Author
-
Nakajima, D., Cypel, M., Bonato, R., Machuca, T. N., Iskender, I., Hashimoto, K., Linacre, V., Chen, M., Coutinho, R., Azad, S., Martinu, T., Waddell, T. K., Hwang, D. M., Husain, S., Liu, M., and Keshavjee, S.
- Abstract
Ex vivolung perfusion (EVLP) is a platform to treat infected donor lungs with antibiotic therapy before lung transplantation. Human donor lungs that were rejected for transplantation because of clinical concern regarding infection were randomly assigned to two groups. In the antibiotic group (n = 8), lungs underwent EVLP for 12 h with high‐dose antibiotics (ciprofloxacin 400 mg or azithromycin 500 mg, vancomycin 15 mg/kg, and meropenem 2 g). In the control group (n = 7), lungs underwent EVLP for 12 h without antibiotics. A quantitative decrease in bacterial counts in bronchoalveolar lavage (BAL) was found in all antibiotic‐treated cases but in only two control cases. Perfusate endotoxin levels at 12 h were significantly lower in the antibiotic group compared with the control group. EVLP with broad‐spectrum antibiotic therapy significantly improved pulmonary oxygenation and compliance and reduced pulmonary vascular resistance. Perfusate endotoxin levels at 12 h were strongly correlated with levels of perfusates tumor necrosis factor α, IL‐1β and macrophage inflammatory proteins 1α and 1β at 12 h. In conclusion, EVLP treatment of infected donor lungs with broad‐spectrum antibiotics significantly reduced BAL bacterial counts and endotoxin levels and improved donor lung function. Broad‐spectrum antibiotic therapy administered during ex vivolung perfusion significantly reduces bacterial burden and endotoxin levels and improves the lung function of donor lungs clinically declined due to infection.
- Published
- 2016
- Full Text
- View/download PDF
13. Gain and Absorption Spectra of Quantum Wire Lasers Diodes Grown on Nonplanar Substrates
- Author
-
BELL COMMUNICATIONS RESEARCH INC RED BANK NJ, Walther, M, Kapon, E, Scherer, A, Song, H, Hwang, D M, Bhat, R, BELL COMMUNICATIONS RESEARCH INC RED BANK NJ, Walther, M, Kapon, E, Scherer, A, Song, H, Hwang, D M, and Bhat, R
- Abstract
Quantum wire (QWR) semiconductor lasers, grown by organometallic chemical vapor deposition OMCVD) on nonplanar substrates, exhibit two dimensional (2D) quantum confinement and sub-mA threshold currents. The in situ formation of the wires in these lasers eliminates excessive nonradiative recombination at their interfaces, which is essential for the efficient operation of these devices. One of the expected advantages of QWR heterostructures is the enhanced optical gain and absorption resulting from the increased density of states at the quasi-1D subbands. This feature would make QWR heterostructures useful for applications in low power consumption integrated optoelectronics. Here, we report the first measured gain and absorption spectra of QWR lasers. The multi-QWR lasers discussed here were grown by OMCVD on V- grooved substrates. Their active regions consist of 4 crescent-shaped GaAs wires, placed at the center of a 2D, graded index AlGaAs optical waveguide. A band structure model of these wires yields electron-heavy hole QWR subband transitions separated by 19meV, with an effective wire width of 15nm for the ground electron state, The subband structure was evident in the amplified spontaneous emission and lasing spectra of the devices, with observed transition energies in good agreement with the calculated values., This Article is from 'Integrated Photonics Research'. Volume 10, ADA255423, p58-59.
- Published
- 1992
14. Identification, characterization, and mapping of expressed sequence tags from an embryonic zebrafish heart cDNA library.
- Author
-
Ton, C, Hwang, D M, Dempsey, A A, Tang, H C, Yoon, J, Lim, M, Mably, J D, Fishman, M C, and Liew, C C
- Abstract
The generation of expressed sequence tags (ESTs) has proven to be a rapid and economical approach by which to identify and characterize expressed genes. We generated 5102 ESTs from a 3-d-old embryonic zebrafish heart cDNA library. Of these, 57.6% matched to known genes, 14.2% matched only to other ESTs, and 27.8% showed no match to any ESTs or known genes. Clustering of all ESTs identified 359 unique clusters comprising 1771 ESTs, whereas the remaining 3331 ESTs did not cluster. This estimates the number of unique genes identified in the data set to be approximately 3690. A total of 1242 unique known genes were used to analyze the gene expression patterns in the zebrafish embryonic heart. These were categorized into seven categories on the basis of gene function. The largest class of genes represented those involved in gene/protein expression (25.9% of known transcripts). This class was followed by genes involved in metabolism (18.7%), cell structure/motility (16.4%), cell signaling and communication (9.6%), cell/organism defense (7.1%), and cell division (4.4%). Unclassified genes constituted the remaining 17.91%. Radiation hybrid mapping was performed for 102 ESTs and comparison of map positions between zebrafish and human identified new synteny groups. Continued comparative analysis will be useful in defining the boundaries of conserved chromosome segments between zebrafish and humans, which will facilitate the transfer of genetic information between the two organisms and improve our understanding of vertebrate evolution.
- Published
- 2000
15. Banff Lung Report: Current knowledge and future research perspectives for diagnosis and treatment of pulmonary antibody-mediated rejection (AMR).
- Author
-
Roux A, Levine DJ, Zeevi A, Hachem R, Halloran K, Halloran PF, Gibault L, Taupin JL, Neil DAH, Loupy A, Adam BA, Mengel M, Hwang DM, Calabrese F, Berry G, and Pavlisko EN
- Subjects
- Allografts, Complement C4 immunology, Gene Expression Profiling, HLA Antigens immunology, Humans, Immunohistochemistry, Isoantibodies immunology, Peptide Fragments immunology, Societies, Medical, Tissue Donors, Transplantation, Homologous, Antibodies immunology, Graft Rejection immunology, Lung immunology, Lung Transplantation
- Abstract
The Lung session of the 2017 14th Banff Foundation for Allograft Pathology Conference, Barcelona focused on the multiple aspects of antibody-mediated rejection (AMR) in lung transplantation. Multidimensional approaches for AMR diagnosis, including classification, histological and immunohistochemical analysis, and donor- specific antibody (DSA) characterization with their current strengths and limitations were reviewed in view of recent research. The group also discussed the role of tissue gene expression analysis in the context of unmet needs in lung transplantation. The current best practice for monitoring of AMR and the therapeutic approach are summarized and highlighted in this report. The working group reached consensus of the major gaps in current knowledge and focused on the unanswered questions regarding pulmonary AMR. An important outcome of the meeting was agreement on the need for future collaborative research projects to address these gaps in the field of lung transplantation., (© 2018 The American Society of Transplantation and the American Society of Transplant Surgeons.)
- Published
- 2019
- Full Text
- View/download PDF
16. A 21-year-old man with systemic-onset juvenile rheumatoid arthritis, cough and progressive dyspnea.
- Author
-
Leber A, Carette S, Chapman KR, Hwang DM, Singer LG, and Marras TK
- Subjects
- Cough etiology, Dyspnea etiology, Humans, Lung Transplantation, Male, Pneumonia etiology, Pneumonia surgery, Young Adult, Arthritis, Juvenile complications, Pneumonia diagnosis
- Abstract
Primary or nonobstructive, endogenous lipoid pneumonia is a rare clinical entity usually associated with an underlying systemic disease. The present report describes a case involving a 21-year-old man with systemic-onset juvenile rheumatoid arthritis who developed primary endogenous lipoid pneumonia. Multiple treatment regimens were attempted; however, definitive management was only achieved through double-lung transplantation.
- Published
- 2010
- Full Text
- View/download PDF
17. Profiling genes expressed in human fetal cartilage using 13,155 expressed sequence tags.
- Author
-
Zhang H, Marshall KW, Tang H, Hwang DM, Lee M, and Liew CC
- Subjects
- Collagen genetics, Connective Tissue Growth Factor, DNA genetics, Endopeptidases genetics, Extracellular Matrix Proteins genetics, Fibroblast Growth Factors genetics, Growth Substances genetics, Humans, Immediate-Early Proteins genetics, Insulin-Like Growth Factor II genetics, Intercellular Signaling Peptides and Proteins genetics, Proteoglycans genetics, Repetitive Sequences, Nucleic Acid, Cartilage, Articular physiology, Expressed Sequence Tags, Fetus physiology, Gene Expression Profiling
- Abstract
Objective: To analyze the gene expression profile of human fetal cartilage by expressed sequence tags (ESTs)., Methods: A human fetal cartilage (8-12 weeks) cDNA library was constructed using the lambda ZAP Express vector. ESTs were obtained by partial sequencing of cDNA clones. The basic local alignment search tool algorithm was used to compare all generated ESTs to known sequences., Results: A total of 13,155 ESTs were analyzed, of which 8696 ESTs (66.1%) matched known genes, 53 ESTs (0.4%) were putatively novel (with no match) and the rest matched other ESTs, genomic DNA and repetitive sequences. Importantly, we identified 2448 unique known genes through non-redundancy analysis of the known gene matches, which were then functionally categorized. The tissue specificity of this library was reflected by its EST profile of the extracellular matrix (ECM) proteins. Collagens were the major transcripts, representing 68.5% of the ECM proteins. Proteoglycans were the second most abundant, constituting 9.5%. Collagen type II was the most abundant gene of all. Glypican 3, decorin and aggrecan were the major transcripts of proteoglycans. Many genes involved in cartilage development were identified, such as insulin-like growth factor-II, its receptor and binding proteins, connective tissue growth factor and fibroblast growth factors. Proteases and their regulatory factors were also identified, including matrix metalloprotease 2 and tissue inhibitor of metalloproteinase 1., Conclusions: The EST approach is an effective way of characterizing the genes expressed in cartilage. These data represent the most extensive molecular information on human fetal cartilage to date. The availability of this information will serve as a basis for further research to identify genes that are essential in cartilage development.
- Published
- 2003
- Full Text
- View/download PDF
18. Identification of differentially expressed genes in cardiac hypertrophy by analysis of expressed sequence tags.
- Author
-
Hwang DM, Dempsey AA, Lee CY, and Liew CC
- Subjects
- Adult, Cardiomegaly metabolism, DNA classification, DNA Primers, Fetal Heart metabolism, Gene Expression Profiling, Gene Library, Humans, Models, Genetic, Molecular Sequence Data, Myocardium metabolism, Proteins genetics, Proteins metabolism, Sequence Analysis, DNA, Cardiomegaly genetics, Expressed Sequence Tags, Gene Expression physiology
- Abstract
Cardiac hypertrophy is an adaptive response to chronic hemodynamic overload. We employed a whole-genome approach using expressed sequence tags (ESTs) to characterize gene transcription and identify new genes overexpressed in cardiac hypertrophy. Analysis of general transcription patterns revealed a proportional increase in transcripts related to cell/organism defense and a decrease in transcripts related to cell structure and motility in hypertrophic hearts compared to normal hearts. Detailed comparison of individual gene expression identified 64 genes potentially overexpressed in hypertrophy, of 232 candidate genes derived from a set of 77,692 cardiac ESTs, including 47,856 ESTs generated in our laboratory. Of these, 29 were good candidates (P < 0.0002) and 35 were weaker candidates (P < 0.005). RT-PCR of a number of these candidate genes demonstrated correspondence of EST-based predictions of gene expression with in vitro levels. Consistent with an organ under various stresses, up to one-half of the good candidates predicted to exhibit differential expression were genes potentially involved in stress response. Analyses of general transcription patterns and of single-gene expression levels were also suggestive of increased protein synthesis in the hypertrophic myocardium. Overall, these results depict a scenario compatible with current understanding of cardiac hypertrophy. However, the identification of several genes not previously known to exhibit increased expression in cardiac hypertrophy (e.g., prostaglandin D synthases; CD59 antigen) also suggests a number of new avenues for further investigation. These data demonstrate the utility of genome-based resources for investigating questions of cardiovascular biology and medicine., (Copyright 2000 Academic Press.)
- Published
- 2000
- Full Text
- View/download PDF
19. A genome-based resource for molecular cardiovascular medicine: toward a compendium of cardiovascular genes.
- Author
-
Hwang DM, Dempsey AA, Wang RX, Rezvani M, Barrans JD, Dai KS, Wang HY, Ma H, Cukerman E, Liu YQ, Gu JR, Zhang JH, Tsui SK, Waye MM, Fung KP, Lee CY, and Liew CC
- Subjects
- Blotting, Northern, Cardiomegaly genetics, Chromosome Mapping, DNA, Complementary genetics, Databases as Topic, Gene Expression, Human Genome Project, Humans, Sequence Tagged Sites, Cardiology methods, Cardiovascular Physiological Phenomena, Genes physiology, Genome, Molecular Biology methods
- Abstract
Background: Large-scale partial sequencing of cDNA libraries to generate expressed sequence tags (ESTs) is an effective means of discovering novel genes and characterizing transcription patterns in different tissues. To catalogue the identities and expression levels of genes in the cardiovascular system, we initiated large-scale sequencing and analysis of human cardiac cDNA libraries., Methods and Results: Using automated DNA sequencing, we generated 43,285 ESTs from human heart cDNA libraries. An additional 41,619 ESTs were retrieved from public databases, for a total of 84,904 ESTs representing more than 26 million nucleotides of raw cDNA sequence data from 13 independent cardiovascular system-based cDNA libraries. Of these, 55% matched to known genes in the Genbank/EMBL/DDBJ databases, 33% matched only to other ESTs, and 12% did not match to any known sequences (designated cardiovascular system-based ESTs, or CVbESTs). ESTs that matched to known genes were classified according to function, allowing for detection of differences in general transcription patterns between various tissues and developmental stages of the cardiovascular system. In silico Northern analysis of known gene matches identified widely expressed cardiovascular genes as well as genes putatively exhibiting greater tissue specificity or developmental stage specificity. More detailed analysis identified 48 genes potentially overexpressed in cardiac hypertrophy, at least 10 of which were previously documented as differentially expressed. Computer-based chromosomal localizations of 1048 cardiac ESTs were performed to further assist in the search for disease-related genes., Conclusions: These data represent the most extensive compilation of cardiovascular gene expression information to date. They further demonstrate the untapped potential of genome research for investigating questions related to cardiovascular biology and represent a first-generation genome-based resource for molecular cardiovascular medicine.
- Published
- 1997
- Full Text
- View/download PDF
20. A modular domain of NifU, a nitrogen fixation cluster protein, is highly conserved in evolution.
- Author
-
Hwang DM, Dempsey A, Tan KT, and Liew CC
- Subjects
- Amino Acid Sequence, Base Sequence, Cloning, Molecular, Fetal Heart, Gene Expression, Genes genetics, Humans, Iron-Sulfur Proteins, Molecular Sequence Data, Myocardium chemistry, Nitrogen Fixation genetics, Organ Specificity, RNA, Messenger analysis, Sequence Alignment, Sequence Analysis, DNA, Sequence Homology, Amino Acid, Sequence Homology, Nucleic Acid, Bacterial Proteins genetics, Conserved Sequence genetics, DNA, Complementary genetics, Proteins genetics
- Abstract
hnifU, a gene exhibiting similarity to nifU genes of nitrogen fixation gene clusters, was identified in the course of expressed sequence tag (EST) generation from a human fetal heart cDNA library. Northern blot of human tissues and polymerase chain reaction (PCR) using human genomic DNA verified that the hnifU gene represented a human gene rather than a microbial contaminant of the cDNA library. Conceptual translation of the hnifU cDNA yielded a protein product bearing 77% and 70% amino acid identity to NifU-like hypothetical proteins from Haemophilus influenzae and Saccharomyces cerevisiae, respectively, and 40-44% identity to the N-terminal regions of NifU proteins from several diazatrophs (i.e., nitrogen-fixing organisms). Pairwise determination of amino acid identities between the NifU-like proteins of nondiazatrophs showed that these NifU-like proteins exhibited higher sequence identity to each other (63-77%) than to the diazatrophic NifU proteins (40-48%). Further, the NifU-like proteins of non-nitrogen-fixing organisms were similar only to the N-terminal region of diazatrophic NifU proteins and therefore identified a novel modular domain in these NifU proteins. These findings support the hypothesis that NifU is indeed a modular protein. The high degree of sequence similarity between NifU-like proteins from species as divergent as humans and H. influenzae suggests that these proteins perform some basic cellular function and may be among the most highly conserved proteins.
- Published
- 1996
- Full Text
- View/download PDF
21. Analysis of expressed sequence tags from a fetal human heart cDNA library.
- Author
-
Hwang DM, Fung YW, Wang RX, Laurenssen CM, Ng SH, Lam WY, Tsui KW, Fung KP, Waye M, and Lee CY
- Subjects
- Adult, Base Sequence, DNA Primers, DNA, Complementary, Heart growth & development, Humans, Molecular Sequence Data, Muscle Proteins genetics, Sequence Tagged Sites, Heart embryology, Myocardium metabolism
- Abstract
Single-pass sequencing of randomly selected cDNA clones to generate expressed sequence tags (ESTs) has been widely used to identify novel genes and to study gene expression in a variety of tissues. We have generated 2244 ESTs from a human fetal heart library (GenBank Accession Nos. R30692-30774 and R56965-58824), which we present in this report. Of these, 51.7% showed no homology to known genes or were similar only to other ESTs, while 48.4% demonstrated homology to known transcripts. A total of 764 ESTs corresponding to known genes were used to study gene expression patterns in the fetal heart and to analyze differences in these patterns from those observed in the adult heart. These analyses demonstrate the utility of ESTs and sequence-tagged clones in comparative studies of gene expression in the cardiovascular system, and they reveal that differential gene expression underlies the structural and functional characteristics of the developing heart.
- Published
- 1995
- Full Text
- View/download PDF
22. Structural basis of specific and efficient phosphorylation of peptides derived from p34cdc2 by a pp60src-related protein tyrosine kinase.
- Author
-
Cheng HC, Litwin CM, Hwang DM, and Wang JH
- Subjects
- Amino Acid Sequence, Animals, CDC2 Protein Kinase analogs & derivatives, CDC2 Protein Kinase chemical synthesis, Cattle, Chromatography, High Pressure Liquid, Kinetics, Molecular Sequence Data, Peptide Fragments chemical synthesis, Peptide Fragments metabolism, Phosphorylation, Protein-Tyrosine Kinases antagonists & inhibitors, Spleen enzymology, CDC2 Protein Kinase metabolism, Protein-Tyrosine Kinases metabolism, Proto-Oncogene Proteins pp60(c-src) metabolism
- Abstract
Cys-cdc2(8-20), a synthetic peptide derived from p34cdc2, was previously reported to be a specific and efficient substrate of a pp60c-src-related tyrosine kinase isolated from bovine spleen (the spleen tyrosine kinase) (Litwin, C.M.E., Cheng, H.-C., and Wang, J.H. (1991) J. Biol. Chem. 266, 2557-2566). The longer peptide, cdc2(1-24), was found to be phosphorylated by the kinase with similar efficiency, and Tyr15 was the only amino acid residue phosphorylated. This indicated that the amino acid sequence of cdc2(8-20) peptide, EKI-GEGTYGVVYK, contained the structural features important for protein tyrosine kinase substrate activity. A stepwise procedure using synthetic peptides was employed to investigate such structural features. First, a computer search of protein sequences homologous to cdc2(8-20) uncovered five protein kinases containing homologous sequence with tyrosine at a position corresponding to Tyr15 of p34cdc2. Second, a peptide derived from ribosomal S6 protein kinase (rsk(436-456] was synthesized. The rsk(436-456) peptide contained a segment, ETIGVGSYSVCKR, which is highly homologous to that of cdc2(8-20). It was found to be a very poor substrate of the spleen tyrosine kinase. Third, peptide analogs of cdc2(6-20) with single substitutions of amino acid residues Lys9, Glu12, Thr14, Gly16, Val18, and Tyr19 by amino acid residues at corresponding positions of rsk were synthesized and tested as spleen tyrosine kinase substrates. Only Glu12 and Thr14 substituted peptide analogs showed decreased substrate activities. (The substrate activity of a peptide is the ability of the peptide to serve as the substrate of the spleen tyrosine kinase. It was determined of the spleen tyrosine kinase. It was determined either by the kinetic parameters (Km and Vmax) of phosphorylation of the peptide or by the initial phosphorylation rate of the peptide by the spleen tyrosine kinase.) An analog with double substitution at Glu12 An analog with double substitution at Glu12 and Thr14 was found to be almost as poor a substrate as the rsk peptide. In addition, peptide analogs with Tyr15 substituted by Phe or D-Tyr had poor substrate activities as well as weak inhibitory activities. Thus, Glu12, Thr14, and Tyr15 residues of p34cdc2 contained structural components essential for the efficient phosphorylation of the peptides derived from p34cdc2 by the pp60c-src-related spleen tyrosine kinase.
- Published
- 1991
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.