163 results on '"Arun, K."'
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2. Coherence between Cellular Responses and in Vitro Splicing Inhibition for the Anti-tumor Drug Pladienolide B and Its Analogs* * This work was supported, in whole or in part, by National Institutes of Health Grants R01CA136762 (to M. S. J.) and 1S10RR022455. This work was also supported by the University of California Cancer Research Coordinating Committee, the California Institute for Quantitative Biosciences (QB3), and the United States Department of State. This article contains supplemental materials.
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Effenberger, Kerstin A, Anderson, David D, Bray, Walter M, Prichard, Beth E, Ma, Nianchun, Adams, Matthew S, Ghosh, Arun K, and Jurica, Melissa S
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Medicinal and Biomolecular Chemistry ,Chemical Sciences ,Cancer ,Antineoplastic Agents ,Epoxy Compounds ,HeLa Cells ,Humans ,Macrolides ,Neoplasm Proteins ,Neoplasms ,Phosphoproteins ,Pyrans ,RNA Splicing ,RNA Splicing Factors ,Ribonucleoprotein ,U2 Small Nuclear ,Spiro Compounds ,Alternative Splicing ,Drug Action ,Enzyme Inhibitors ,Nucleus ,Hela Cells ,Biological Sciences ,Medical and Health Sciences ,Biochemistry & Molecular Biology ,Biological sciences ,Biomedical and clinical sciences ,Chemical sciences - Abstract
Pladienolide B (PB) is a potent cancer cell growth inhibitor that targets the SF3B1 subunit of the spliceosome. There is considerable interest in the compound as a potential chemotherapeutic, as well as a tool to study SF3B1 function in splicing and cancer development. The molecular structure of PB, a bacterial natural product, contains a 12-member macrolide ring with an extended epoxide-containing side chain. Using a novel concise enantioselective synthesis, we created a series of PB structural analogs and the structurally related compound herboxidiene. We show that two methyl groups in the PB side chain, as well as a feature of the macrolide ring shared with herboxidiene, are required for splicing inhibition in vitro. Unexpectedly, we find that the epoxy group contributes only modestly to PB potency and is not absolutely necessary for activity. The orientations of at least two chiral centers off the macrolide ring have no effect on PB activity. Importantly, the ability of analogs to inhibit splicing in vitro directly correlated with their effects in a series of cellular assays. Those effects likely arise from inhibition of some, but not all, endogenous splicing events in cells, as previously reported for the structurally distinct SF3B1 inhibitor spliceostatin A. Together, our data support the idea that the impact of PB on cells is derived from its ability to impair the function of SF3B1 in splicing and also demonstrate that simplification of the PB scaffold is feasible.
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- 2014
3. Genetically encoded intrabody sensors report the interaction and trafficking of β-arrestin 1 upon activation of G-protein–coupled receptors
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Punita Kumari, Debarati Roy, Madhu Chaturvedi, Arun K. Shukla, Hemlata Dwivedi-Agnihotri, Shubhi Pandey, Aylin C. Hanyaloglu, Ashish Srivastava, Michel Bouvier, Silvia Sposini, Badr Sokrat, Mithu Baidya, Society for Endocrinology, and Genesis Research Trust
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0301 basic medicine ,Biochemistry & Molecular Biology ,Cell signaling ,G protein-coupled receptor (GPCR) ,confocal microscopy ,Endocytosis ,Biochemistry ,Intrabody ,Receptors, G-Protein-Coupled ,Immunoglobulin Fab Fragments ,03 medical and health sciences ,synthetic antibody ,trafficking ,Functional selectivity ,Arrestin ,Humans ,cell signaling ,Molecular Biology ,G-protein–coupled receptors (GPCRs) ,11 Medical and Health Sciences ,β-arrestins ,G protein-coupled receptor ,bioluminescence resonance energy transfer (BRET) ,030102 biochemistry & molecular biology ,biology ,arrestin ,Chemistry ,Cell Biology ,06 Biological Sciences ,biosensors ,protein phosphorylation ,Synthetic antibody ,Cell biology ,Protein Transport ,intrabody ,HEK293 Cells ,beta-Arrestin 1 ,030104 developmental biology ,biased agonism ,biology.protein ,cellular signaling ,Signal transduction ,03 Chemical Sciences ,signal transduction ,hormones, hormone substitutes, and hormone antagonists - Abstract
Agonist stimulation of G protein-coupled receptors (GPCRs) typically leads to phosphorylation of GPCRs and binding to multifunctional proteins called β-arrestins (βarrs). The GPCR-βarr interaction critically contributes to GPCR desensitization, endocytosis, and downstream signaling, and GPCR-βarr complex formation can be used as a generic readout of GPCR and βarr activation. Although several methods are currently available to monitor GPCR-βarr interactions, additional sensors to visualize them may expand the toolbox and complement existing methods. We have previously described antibody fragments (FABs) that recognize activated βarr1 upon its interaction with the vasopressin V2 receptor C-terminal phosphopeptide (V2Rpp). Here, we demonstrate that these FABs efficiently report the formation of a GPCR-βarr1 complex for a broad set of chimeric GPCRs harboring the V2R C terminus. We adapted these FABs to an intrabody format by converting them to single-chain variable fragments (ScFvs) and used them to monitor the localization and trafficking of βarr1 in live cells. We observed that upon agonist simulation of cells expressing chimeric GPCRs, these intrabodies first translocate to the cell surface, followed by trafficking into intracellular vesicles. The translocation pattern of intrabodies mirrored that of βarr1, and the intrabodies co-localized with βarr1 at the cell surface and in intracellular vesicles. Interestingly, we discovered that intrabody sensors can also report βarr1 recruitment and trafficking for several unmodified GPCRs. Our characterization of intrabody sensors for βarr1 recruitment and trafficking expands currently available approaches to visualize GPCR-βarr1 binding, which may help decipher additional aspects of GPCR signaling and regulation.
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- 2020
4. Antagonizing binding of cell cycle and apoptosis regulatory protein 1 (CARP-1) to the NEMO/IKKγ protein enhances the anticancer effect of chemotherapy
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Jaganathan Venkatesh, Arun K. Rishi, Lisa Polin, Sijana H. Dzinic, Edi Levi, James W. Gauld, Paul Meister, Vino T. Cheriyan, Magesh Muthu, and Sreeja C. Sekhar
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Models, Molecular ,0301 basic medicine ,medicine.medical_treatment ,Antineoplastic Agents ,Cell Cycle Proteins ,IκB kinase ,Models, Biological ,Biochemistry ,Epitopes ,03 medical and health sciences ,Epidermal growth factor ,Cell Line, Tumor ,medicine ,Animals ,Phosphorylation ,Molecular Biology ,Transcription factor ,Cell Proliferation ,Mice, Inbred BALB C ,030102 biochemistry & molecular biology ,Kinase ,Chemistry ,Transcription Factor RelA ,Cell Biology ,Cell cycle ,I-kappa B Kinase ,Kinetics ,030104 developmental biology ,Cytokine ,Doxorubicin ,Cancer cell ,Cancer research ,Cytokines ,Thermodynamics ,Tumor necrosis factor alpha ,Cisplatin ,Inflammation Mediators ,Apoptosis Regulatory Proteins ,DNA Damage ,Protein Binding ,Signal Transduction - Abstract
NF-κB is a pro-inflammatory transcription factor that critically regulates immune responses and other distinct cellular pathways. However, many NF-κB–mediated pathways for cell survival and apoptosis signaling in cancer remain to be elucidated. Cell cycle and apoptosis regulatory protein 1 (CARP-1 or CCAR1) is a perinuclear phosphoprotein that regulates signaling induced by anticancer chemotherapy and growth factors. Although previous studies have reported that CARP-1 is a part of the NF-κB proteome, regulation of NF-κB signaling by CARP-1 and the molecular mechanism(s) involved are unclear. Here, we report that CARP-1 directly binds the NF-κB–activating kinase IκB kinase subunit γ (NEMO or NF-κB essential modulator) and regulates the chemotherapy-activated canonical NF-κB pathway. Importantly, blockade of NEMO–CARP-1 binding diminished NF-κB activation, indicated by reduced phosphorylation of its subunit p65/RelA by the chemotherapeutic agent adriamycin (ADR), but not NF-κB activation induced by tumor necrosis factor α (TNFα), interleukin (IL)-1β, or epidermal growth factor. High-throughput screening of a chemical library yielded a small molecule inhibitor of NEMO–CARP-1 binding, termed selective NF-κB inhibitor 1 (SNI)-1). We noted that SNI-1 enhances chemotherapy-dependent growth inhibition of a variety of cancer cells, including human triple-negative breast cancer (TNBC) and patient-derived TNBC cells in vitro, and attenuates chemotherapy-induced secretion of the pro-inflammatory cytokines TNFα, IL-1β, and IL-8. SNI-1 also enhanced ADR or cisplatin inhibition of murine TNBC tumors in vivo and reduced systemic levels of pro-inflammatory cytokines. We conclude that inhibition of NEMO–CARP-1 binding enhances responses of cancer cells to chemotherapy.
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- 2020
5. Genetically encoded intrabody sensors report the interaction and trafficking of β-arrestin 1 upon activation of G-protein–coupled receptors
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Baidya, Mithu, primary, Kumari, Punita, additional, Dwivedi-Agnihotri, Hemlata, additional, Pandey, Shubhi, additional, Sokrat, Badr, additional, Sposini, Silvia, additional, Chaturvedi, Madhu, additional, Srivastava, Ashish, additional, Roy, Debarati, additional, Hanyaloglu, Aylin C., additional, Bouvier, Michel, additional, and Shukla, Arun K., additional
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- 2020
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6. Antagonizing binding of cell cycle and apoptosis regulatory protein 1 (CARP-1) to the NEMO/IKKγ protein enhances the anticancer effect of chemotherapy
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Venkatesh, Jaganathan, primary, Sekhar, Sreeja C., additional, Cheriyan, Vino T., additional, Muthu, Magesh, additional, Meister, Paul, additional, Levi, Edi, additional, Dzinic, Sijana, additional, Gauld, James W., additional, Polin, Lisa A., additional, and Rishi, Arun K., additional
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- 2020
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7. Partial ligand-receptor engagement yields functional bias at the human complement receptor, C5aR1
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Pandey, Shubhi, primary, Li, Xaria X., additional, Srivastava, Ashish, additional, Baidya, Mithu, additional, Kumari, Punita, additional, Dwivedi, Hemlata, additional, Chaturvedi, Madhu, additional, Ghosh, Eshan, additional, Woodruff, Trent M., additional, and Shukla, Arun K., additional
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- 2019
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8. Characterization of a Drosophila Ortholog of the Cdc7 Kinase
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Navnath Gavande, Rob Stephenson, Vikki M. Weake, Arun K. Ghosh, and Marcus R. Hosler
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animal structures ,DNA replication initiation ,biology ,DNA replication ,Egg protein ,Cell Biology ,Serine threonine protein kinase ,biology.organism_classification ,Biochemistry ,Molecular biology ,Cell biology ,Endoreduplication ,Drosophila melanogaster ,Kinase activity ,Molecular Biology ,Drosophila Protein - Abstract
Cdc7 is a serine-threonine kinase that phosphorylates components of the pre-replication complex during DNA replication initiation. Cdc7 is highly conserved, and Cdc7 orthologs have been characterized in organisms ranging from yeast to humans. Cdc7 is activated specifically during late G1/S phase by binding to its regulatory subunit, Dbf4. Drosophila melanogaster contains a Dbf4 ortholog, Chiffon, which is essential for chorion amplification in Drosophila egg chambers. However, no Drosophila ortholog of Cdc7 has yet been characterized. Here, we report the functional and biochemical characterization of a Drosophila ortholog of Cdc7. Co-expression of Drosophila Cdc7 and Chiffon is able to complement a growth defect in yeast containing a temperature-sensitive Cdc7 mutant. Cdc7 and Chiffon physically interact and can be co-purified from insect cells. Cdc7 phosphorylates the known Cdc7 substrates Mcm2 and histone H3 in vitro, and Cdc7 kinase activity is stimulated by Chiffon and inhibited by the Cdc7-specific inhibitor XL413. Drosophila egg chamber follicle cells deficient for Cdc7 have a defect in two types of DNA replication, endoreplication and chorion gene amplification. However, follicle cells deficient for Chiffon have a defect in chorion gene amplification but still undergo endocycling. Our results show that Cdc7 interacts with Chiffon to form a functional Dbf4-dependent kinase complex and that Cdc7 is necessary for DNA replication in Drosophila egg chamber follicle cells. Additionally, we show that Chiffon is a member of an expanding subset of DNA replication initiation factors that are not strictly required for endoreplication in Drosophila.
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- 2015
9. Low Temperature and Chemical Rescue Affect Molecular Proximity of ΔF508-Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) and Epithelial Sodium Channel (ENaC)
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Estelle Cormet-Boyaka, Vladimir Parpura, Yawar J. Qadri, Arun K. Rooj, Bakhrom K. Berdiev, William Lee, and Catherine M. Fuller
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Epithelial sodium channel ,congenital, hereditary, and neonatal diseases and abnormalities ,medicine.medical_specialty ,Cystic Fibrosis ,Cystic Fibrosis Transmembrane Conductance Regulator ,Biochemistry ,Cystic fibrosis ,Membrane Biology ,Internal medicine ,Fluorescence Resonance Energy Transfer ,medicine ,Humans ,Epithelial Sodium Channels ,ΔF508 ,Molecular Biology ,Ion transporter ,Ion channel ,Sequence Deletion ,Ion Transport ,biology ,urogenital system ,Chemistry ,Cell Membrane ,Sodium ,Cell Biology ,respiratory system ,Sodium ion transport ,medicine.disease ,digestive system diseases ,Cystic fibrosis transmembrane conductance regulator ,respiratory tract diseases ,Amiloride ,Cell biology ,Cold Temperature ,Protein Subunits ,Protein Transport ,HEK293 Cells ,Endocrinology ,biology.protein ,medicine.drug - Abstract
An imbalance of chloride and sodium ion transport in several epithelia is a feature of cystic fibrosis (CF), an inherited disease that is a consequence of mutations in the cftr gene. The cftr gene codes for a Cl(-) channel, the cystic fibrosis transmembrane conductance regulator (CFTR). Some mutations in this gene cause the balance between Cl(-) secretion and Na(+) absorption to be disturbed in the airways; Cl(-) secretion is impaired, whereas Na(+) absorption is elevated. Enhanced Na(+) absorption through the epithelial sodium channel (ENaC) is attributed to the failure of mutated CFTR to restrict ENaC-mediated Na(+) transport. The mechanism of this regulation is controversial. Recently, we have found evidence for a close association of wild type (WT) CFTR and WT ENaC, further underscoring the role of ENaC along with CFTR in the pathophysiology of CF airway disease. In this study, we have examined the association of ENaC subunits with mutated ΔF508-CFTR, the most common mutation in CF. Deletion of phenylalanine at position 508 (ΔF508) prevents proper processing and targeting of CFTR to the plasma membrane. When ΔF508-CFTR and ENaC subunits were co-expressed in HEK293T cells, we found that individual ENaC subunits could be co-immunoprecipitated with ΔF508-CFTR, much like WT CFTR. However, when we evaluated the ΔF508-CFTR and ENaC association using fluorescence resonance energy transfer (FRET), FRET efficiencies were not significantly different from negative controls, suggesting that ΔF508-CFTR and ENaC are not in close proximity to each other under basal conditions. However, with partial correction of ΔF508-CFTR misprocessing by low temperature and chemical rescue, leading to surface expression as assessed by total internal reflection fluorescence (TIRF) microscopy, we observed a positive FRET signal. Our findings suggest that the ΔF508 mutation alters the close association of CFTR and ENaC.
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- 2012
10. Antagonists of Anaphase-promoting Complex (APC)-2-Cell Cycle and Apoptosis Regulatory Protein (CARP)-1 Interaction Are Novel Regulators of Cell Growth and Apoptosis
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Edi Levi, Robert Kilkuskie, Fred R. Miller, Liyue Zhang, Scott D. Larsen, Arun K. Rishi, Anil Wali, Wenjuan Wu, Debra J. Bevis, Lisa Polin, Vineshkumar Thidil Puliyappadamba, and Russell L. Finley
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Ubiquitin-Protein Ligases ,Apoptosis ,Cell Cycle Proteins ,CDC20 ,Biology ,Biochemistry ,Anaphase-Promoting Complex-Cyclosome ,Mice ,Cell Line, Tumor ,Chlorocebus aethiops ,Protein Interaction Mapping ,Thiadiazoles ,Animals ,Humans ,Spiro Compounds ,Cyclin B1 ,Molecular Biology ,Cell Proliferation ,Inhibitor of apoptosis domain ,Cell growth ,Cell Cycle ,Ubiquitin-Protein Ligase Complexes ,Cell Biology ,Cell cycle ,Molecular biology ,Cell biology ,Ubiquitin ligase ,Kinetics ,Gene Expression Regulation ,COS Cells ,biology.protein ,sense organs ,Anaphase-promoting complex ,Signal transduction ,Apoptosis Regulatory Proteins ,HeLa Cells ,Signal Transduction - Abstract
CARP-1/CCAR1, a perinuclear phosphoprotein, is a regulator of cell growth and apoptosis signaling. Although CARP-1 is a regulator of chemotherapy-dependent apoptosis, it is also a part of the NF-κB proteome and a co-activator of steroid/thyroid nuclear receptors as well as β-catenin signaling. Our yeast two-hybrid screen revealed CARP-1 binding with the anaphase-promoting complex/cyclosome E3 ubiquitin ligase component APC-2 protein. CARP-1 also binds with anaphase-promoting complex/cyclosome co-activators Cdc20 and Cdh1. Following mapping of the minimal epitopes involved in CARP-1 binding with APC-2, a fluorescence polarization assay was established that indicated a dissociation constant (K(d)) of 480 nm for CARP-1/APC-2 binding. Fluorescence polarization assay-based high throughput screening of a chemical library yielded several small molecule antagonists of CARP-1/APC-2 binding, termed CARP-1 functional mimetics. CFM-4 (1(2-chlorobenzyl)-5'-phenyl-3'H-spiro[indoline-3,2'-[1,3,4]thiadiazol]-2-one), a lead compound, binds with and stimulates CARP-1 expression. CFM-4 prevents CARP-1 binding with APC-2, causes G(2)M cell cycle arrest, and induces apoptosis with an IC(50) range of 10-15 μm. Apoptosis signaling by CFM-4 involves activation of caspase-8 and -9 and caspase-mediated ubiquitin-proteasome pathway-independent loss of cyclin B1 and Cdc20 proteins. Depletion of CARP-1, however, interferes with CFM-4-dependent cell growth inhibition, activation of caspases, and apoptosis. Because CFM-4 also suppresses growth of drug-resistant human breast cancer cells without affecting the growth of human breast epithelial MCF-10A cells, elevating CARP-1 by CFM-4 and consequent apoptosis could in principle be exploited to further elucidate, and perhaps effectively target, often deregulated cell cycle pathways in pathological conditions, including cancer.
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- 2011
11. Expression of miR-33 from an SREBP2 Intron Inhibits Cholesterol Export and Fatty Acid Oxidation*
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Isabelle Leclercq, Nicolas Lanthier, Olivier Haumont, Charles F. Burant, Guido T. Bommer, Isabelle Gerin, Laure-Alix Clerbaux, Arun K. Das, and Ormond A. MacDougald
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Male ,miR-33 ,Fatty acid degradation ,Biology ,Biochemistry ,Mice ,chemistry.chemical_compound ,Animals ,Humans ,Molecular Biology ,Beta oxidation ,Phospholipids ,chemistry.chemical_classification ,Fatty Acids ,Lentivirus ,Fatty acid ,Lipid metabolism ,Cell Biology ,Introns ,Sterol regulatory element-binding protein ,Mice, Inbred C57BL ,MicroRNAs ,Metabolism ,Cholesterol ,Gene Expression Regulation ,chemistry ,ABCA1 ,biology.protein ,lipids (amino acids, peptides, and proteins) ,Sterol regulatory element-binding protein 2 ,Sterol Regulatory Element Binding Protein 2 - Abstract
The regulation of synthesis, degradation, and distribution of lipids is crucial for homeostasis of organisms and cells. The sterol regulatory element-binding protein (SREBP) transcription factor family is post-translationally activated in situations of reduced lipid abundance and activates numerous genes involved in cholesterol, fatty acid, and phospholipid synthesis. In this study, we provide evidence that the primary transcript of SREBP2 contains an intronic miRNA (miR-33) that reduces cellular cholesterol export via inhibition of translation of the cholesterol export pump ABCA1. Notably, miR-33 also inhibits translation of several transcripts encoding proteins involved in fatty acid β-oxidation including CPT1A, HADHB, and CROT, thereby reducing fatty acid degradation. The genetic locus encoding SREBP2 and miR-33 therefore contains a protein that increases lipid synthesis and a miRNA that prevents export and degradation of newly synthesized lipids. These results add an additional layer of complexity to our understanding of lipid homeostasis and might open possibilities for future therapeutic intervention.
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- 2010
12. Arresting a Transient Receptor Potential (TRP) Channel
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Kunhong Xiao, Robert J. Lefkowitz, Seungkirl Ahn, Wolfgang Liedtke, Sudha K. Shenoy, Arun K. Shukla, and Jihee Kim
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TRPV4 ,0303 health sciences ,Angiotensin receptor ,genetic structures ,biology ,Beta-Arrestins ,media_common.quotation_subject ,Cell Biology ,Biochemistry ,Ubiquitin ligase ,Cell biology ,03 medical and health sciences ,Transient receptor potential channel ,0302 clinical medicine ,biology.protein ,Internalization ,Receptor ,Molecular Biology ,030217 neurology & neurosurgery ,Ion channel ,030304 developmental biology ,media_common - Abstract
β-Arrestins, originally discovered to desensitize activated G protein-coupled receptors, (aka seven-transmembrane receptors, 7TMRs) also mediate 7TMR internalization and G protein-independent signaling via these receptors. More recently, several regulatory roles of β-arrestins for atypical 7TMRs and non-7TM receptors have emerged. Here, we uncover an entirely novel regulatory role of β-arrestins in cross-talk between the angiotensin receptor (AT1aR) and a member of the transient receptor potential (TRP) ion channel family, TRPV4. AT1aR and TRPV4 form a constitutive complex in the plasma membrane, and angiotensin stimulation leads to recruitment of β-arrestin 1 to this complex. Surprisingly, angiotensin stimulation results in ubiquitination of TRPV4, a process that requires β-arrestin 1, and subsequently to internalization and functional down-regulation of TRPV4. β-Arrestin 1 interacts with, and acts as an adaptor for AIP4, an E3 ubiquitin ligase responsible for TRPV4 ubiquitination. Thus, our data provide the first evidence of a functional link between β-arrestins and TRPV4 and uncovers an entirely novel mechanism to maintain appropriate intracellular Ca2+ concentration to avoid excessive Ca2+ signaling.
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- 2010
13. Repair of Laser-localized DNA Interstrand Cross-links in G1 Phase Mammalian Cells
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Michael M. Seidman, Arun K. Thazhathveetil, Dennis Thapa, Parameswary A. Muniandy, and Su-ting Liu
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Genome instability ,DNA Repair ,DNA repair ,DNA damage ,Biology ,Biochemistry ,Cell Line ,Homology directed repair ,DNA Adducts ,chemistry.chemical_compound ,Angelicin ,Furocoumarins ,Animals ,Humans ,Molecular Biology ,Psoralen ,Molecular Structure ,Lasers ,Ficusin ,G1 Phase ,DNA ,Cell Biology ,DNA repair protein XRCC4 ,Molecular biology ,Intercalating Agents ,DNA-Binding Proteins ,Cross-Linking Reagents ,chemistry ,DNA: Replication, Repair, Recombination, and Chromosome Dynamics ,DNA Damage ,Nucleotide excision repair - Abstract
Interstrand cross-links (ICLs) are absolute blocks to transcription and replication and can provoke genomic instability and cell death. Studies in bacteria define a two-stage repair scheme, the first involving recognition and incision on either side of the cross-link on one strand (unhooking), followed by recombinational repair or lesion bypass synthesis. The resultant monoadduct is removed in a second stage by nucleotide excision repair. In mammalian cells, there are multiple, but poorly defined, pathways, with much current attention on repair in S phase. However, many questions remain, including the efficiency of repair in the absence of replication, the factors involved in cross-link recognition, and the timing and demarcation of the first and second repair cycles. We have followed the repair of laser-localized lesions formed by psoralen (cross-links/monoadducts) and angelicin (only monoadducts) in mammalian cells. Both were repaired in G(1) phase by nucleotide excision repair-dependent pathways. Removal of psoralen adducts was blocked in XPC-deficient cells but occurred with wild type kinetics in cells deficient in DDB2 protein (XPE). XPC protein was rapidly recruited to psoralen adducts. However, accumulation of DDB2 was slow and XPC-dependent. Inhibition of repair DNA synthesis did not interfere with DDB2 recruitment to angelicin but eliminated recruitment to psoralen. Our results demonstrate an efficient ICL repair pathway in G(1) phase cells dependent on XPC, with entry of DDB2 only after repair synthesis that completes the first repair cycle. DDB2 accumulation at sites of cross-link repair is a marker for the start of the second repair cycle.
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- 2009
14. Potent Inhibition of HIV-1 Replication by Novel Non-peptidyl Small Molecule Inhibitors of Protease Dimerization
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Jianfeng Li, Yasuhiro Koh, Tatsuo Shioda, Masayuki Amano, Shintaro Matsumi, Arun K. Ghosh, Debananda Das, David A. Davis, Sofiya Leschenko, Robert Yarchoan, Hiroaki Mitsuya, and Abigail Baldridge
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Receptors, CCR5 ,Pyridines ,medicine.medical_treatment ,Biology ,Virus Replication ,Biochemistry ,HIV Protease ,Chlorocebus aethiops ,Fluorescence Resonance Energy Transfer ,medicine ,Animals ,Humans ,Molecular Biology ,Darunavir ,Sulfonamides ,Protease ,COS cells ,Dose-Response Relationship, Drug ,HIV Protease Inhibitors ,Cell Biology ,Small molecule ,Enzyme Activation ,NS2-3 protease ,Förster resonance energy transfer ,Pyrones ,CCR5 Receptor Antagonists ,CD4 Antigens ,COS Cells ,HIV-1 ,Dimerization ,Protein Processing, Post-Translational ,Tipranavir ,MASP1 ,medicine.drug - Abstract
Dimerization of HIV-1 protease subunits is essential for its proteolytic activity, which plays a critical role in HIV-1 replication. Hence, the inhibition of protease dimerization represents a unique target for potential intervention of HIV-1. We developed an intermolecular fluorescence resonance energy transfer-based HIV-1-expression assay employing cyan and yellow fluorescent protein-tagged protease monomers. Using this assay, we identified non-peptidyl small molecule inhibitors of protease dimerization. These inhibitors, including darunavir and two experimental protease inhibitors, blocked protease dimerization at concentrations of as low as 0.01 microm and blocked HIV-1 replication with IC(50) values of 0.0002-0.48 microm. These agents also inhibited the proteolytic activity of mature protease. Other approved anti-HIV-1 agents examined except tipranavir, a CCR5 inhibitor, and soluble CD4 failed to block the dimerization event. Once protease monomers dimerize to become mature protease, mature protease is not dissociated by this dimerization inhibition mechanism, suggesting that these agents block dimerization at the nascent stage of protease maturation. The proteolytic activity of mature protease that managed to undergo dimerization despite the presence of these agents is likely to be inhibited by the same agents acting as conventional protease inhibitors. Such a dual inhibition mechanism should lead to highly potent inhibition of HIV-1.
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- 2007
15. Cell Cycle- and Apoptosis-regulatory Protein-1 Is Involved in Apoptosis Signaling by Epidermal Growth Factor Receptor
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Edi Levi, Adhip P.N. Majumdar, Arun K. Rishi, Anil Wali, Yingjie Yu, Jyoti Nautiyal, Yan Jiang, Joseph A. Fontana, and Liyue Zhang
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p38 mitogen-activated protein kinases ,Apoptosis ,Cell Cycle Proteins ,Biology ,p38 Mitogen-Activated Protein Kinases ,Biochemistry ,chemistry.chemical_compound ,Cell Line, Tumor ,Humans ,Epidermal growth factor receptor ,Tyrosine ,Molecular Biology ,Glycoproteins ,Inhibitor of apoptosis domain ,Gefitinib ,Tyrosine phosphorylation ,Cell Biology ,Cell cycle ,Caspase 9 ,Cell biology ,Enzyme Activation ,ErbB Receptors ,chemistry ,Caspases ,Quinazolines ,Cancer research ,biology.protein ,Phosphorylation ,sense organs ,Apoptosis Regulatory Proteins ,Signal Transduction - Abstract
CARP-1, a novel apoptosis inducer, regulates apoptosis signaling by diverse agents, including adriamycin and growth factors. Epidermal growth factor receptor (EGFR)-related protein (ERRP), a pan-ErbB inhibitor, inhibits EGFR and stimulates apoptosis. Treatments of cells with ERRP or Iressa (an EGFR tyrosine kinase inhibitor) results in elevated CARP-1 levels, whereas antisense-dependent depletion of CARP-1 causes inhibition of apoptosis by ERRP. CARP-1 is a tyrosine-phosphorylated protein, and ERRP treatments cause elevated tyrosine phosphorylation of CARP-1. CARP-1 contains multiple, nonoverlapping apoptosis-inducing subdomains; one such subdomain is present within amino acids 1-198. Wild-type or CARP-1-(1-198) proteins that have substitution of tyrosine 192 to phenylalanine abrogate apoptosis by ERRP. In addition, apoptosis mediated by wild type or CARP-1-(1-198), and not CARP-1-(1-198(Y192F)), results in activation of caspase-9 and increased phosphorylation of p38 MAPK. However, the expression of dominant-negative forms of p38 MAPK activators MKK3 or MKK6 proteins inhibits apoptosis induced by both the full-length and truncated (amino acids 1-198) proteins. Together, data demonstrate that tyrosine 192 of CARP-1 is a target of apoptosis signaling, and CARP-1, in turn, promotes apoptosis by activating p38 MAPK and caspase-9.
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- 2006
16. Altered HIV-1 Gag Protein Interactions with Cyclophilin A (CypA) on the Acquisition of H219Q and H219P Substitutions in the CypA Binding Loop
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Khaja Azhar Hussain, Yasuhiro Suzuki, Hiroyuki Gatanaga, Damaris D. Yeh, Hiroaki Mitsuya, Arun K. Ghosh, and Debananda Das
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CD4-Positive T-Lymphocytes ,Models, Molecular ,Protein Conformation ,Amino Acid Motifs ,Blotting, Western ,HIV Core Protein p24 ,Molecular Conformation ,Cypa ,Plasma protein binding ,Biology ,Biochemistry ,Jurkat cells ,Cell Line ,Jurkat Cells ,Cyclophilin A ,Protein structure ,Chlorocebus aethiops ,Animals ,Humans ,Enzyme Inhibitors ,Molecular Biology ,COS cells ,virus diseases ,Hydrogen Bonding ,Cell Biology ,Group-specific antigen ,biology.organism_classification ,Recombinant Proteins ,Protein Structure, Tertiary ,Cell biology ,Kinetics ,Models, Chemical ,Viral replication ,COS Cells ,Mutation ,HIV-1 ,Leukocytes, Mononuclear ,Peptide Hydrolases ,Protein Binding - Abstract
HIV-1 Gag protein interaction with cyclophilin A (CypA) is critical for viral fitness. Among the amino acid substitutions identified in Gag noncleavage sites in HIV-1 variants resistant to protease inhibitors, H219Q (Gatanaga, H., Suzuki, Y., Tsang, H., Yoshimura, K., Kavlick, M. F., Nagashima, K., Gorelick, R. J., Mardy, S., Tang, C., Summers, M. F., and Mitsuya, H. (2002) J. Biol. Chem. 277, 5952-5961) and H219P substitutions in the viral CypA binding loop confer the greatest replication advantage to HIV-1. These substitutions represent polymorphic amino acid residues. We found that the replication advantage conferred by these substitutions was far greater in CypA-rich MT-2 and H9 cells than in Jurkat cells and peripheral blood mononuclear cells (PBM), both of which contained less CypA. High intracellular CypA content in H9 and MT-2 cells, resulting in excessive CypA levels in virions, limited wild-type HIV-1 (HIV-1(WT)) replication and H219Q introduction into HIV-1 (HIV-1(H219Q)), reduced CypA incorporation of HIV-1, and potentiated viral replication. H219Q introduction also restored the otherwise compromised replication of HIV-1(P222A) in PBM, although the CypA content in HIV-1(H219Q/P222A) was comparable with that in HIV-1(P222A), suggesting that H219Q affected the conformation of the CypA-binding motif, rendering HIV-1 replicative in a low CypA environment. Structural modeling analyses revealed that although hydrogen bonds are lost with H219Q and H219P substitutions, no significant distortion of the CypA binding loop of Gag occurred. The loop conformation of HIV-1(P222A) was found highly distorted, although H219Q introduction to HIV-1 restored the conformation of the loop close to that of HIV-1 (P222A). The present data suggested that the effect of CypA on HIV-1 replicative (WT) ability is bimodal (both high and low CypA content limits HIV-1 replication), that the conformation of the CypA binding region of Gag is important for viral fitness, and that the function of CypA is to maintain the conformation.
- Published
- 2006
17. Identification and Characterization of a Cell Cycle and Apoptosis Regulatory Protein-1 as a Novel Mediator of Apoptosis Signaling by Retinoid CD437
- Author
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Arun K. Rishi, Yingjie Yu, Anil Wali, Joseph A. Fontana, Adhip P.N. Majumdar, Ramzi M. Mohammad, Uwe Reichert, Liyue Zhang, James S. Hatfield, Madanamohan Boyanapalli, and Marcia I. Dawson
- Subjects
DNA, Complementary ,Time Factors ,Cell cycle checkpoint ,medicine.drug_class ,Blotting, Western ,Cell ,Oligonucleotides ,Tetrazolium Salts ,Antineoplastic Agents ,Apoptosis ,Cell Cycle Proteins ,Biology ,Models, Biological ,Biochemistry ,Cell Line ,Proto-Oncogene Proteins c-myc ,Open Reading Frames ,Retinoids ,Tumor Cells, Cultured ,medicine ,Humans ,Neoplasms, Glandular and Epithelial ,Retinoid ,Cloning, Molecular ,Coloring Agents ,Cyclin B1 ,3' Untranslated Regions ,Molecular Biology ,Cell Nucleus ,Inhibitor of apoptosis domain ,Cell Biology ,Oligonucleotides, Antisense ,Cell cycle ,Flow Cytometry ,Precipitin Tests ,Cell biology ,Thiazoles ,Retroviridae ,medicine.anatomical_structure ,Gene Expression Regulation ,Doxorubicin ,Cancer cell ,Electrophoresis, Polyacrylamide Gel ,sense organs ,5' Untranslated Regions ,Apoptosis Regulatory Proteins ,Plasmids ,Protein Binding - Abstract
CD437, a novel retinoid, causes cell cycle arrest and apoptosis in a number of cancer cells including human breast carcinoma (HBC) by utilizing an undefined retinoic acid receptor/retinoid X receptor-independent mechanism. To delineate mediators of CD437 signaling, we utilized a random antisense-dependent functional knockout genetic approach. We identified a cDNA that encodes approximately 130-kDa HBC cell perinuclear protein (termed CARP-1). Treatments with CD437 or chemotherapeutic agent adriamycin, as well as serum deprivation of HBC cells, stimulate CARP-1 expression. Reduced levels of CARP-1 result in inhibition of apoptosis by CD437 or adriamycin, whereas increased expression of CARP-1 causes elevated levels of cyclin-dependent kinase inhibitor p21WAF1/CIP1 and apoptosis. CARP-1 interacts with 14-3-3 protein as well as causes reduced expression of cell cycle regulatory genes including c-Myc and cyclin B1. Loss of c-Myc sensitizes cells to apoptosis by CARP-1, whereas expression of c-Myc or 14-3-3 inhibits CARP-1-dependent apoptosis. Thus, apoptosis induction by CARP-1 involves sequestration of 14-3-3 and CARP-1-mediated altered expression of multiple cell cycle regulatory genes. Identification of CARP-1 as a key mediator of signaling by CD437 or adriamycin allows for delineation of pathways that, in turn, may prove beneficial for design and targeting of novel antitumor agents.
- Published
- 2003
18. Reactive Chlorinating Species Produced during Neutrophil Activation Target Tissue Plasmalogens
- Author
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David A. Ford, Carolyn J. Albert, Fong-Fu Hsu, Jan R. Crowley, Robert B. Wysolmerski, and Arun K. Thukkani
- Subjects
Chemical ionization ,Endothelium ,Chemotaxis ,Cell Biology ,Vinyl ether ,Biochemistry ,In vitro ,Endothelial stem cell ,chemistry.chemical_compound ,medicine.anatomical_structure ,chemistry ,Phorbol ,medicine ,Gas chromatography–mass spectrometry ,Molecular Biology ,medicine.drug - Abstract
Recently α-chloro fatty aldehydes have been shown to be products of reactive chlorinating species targeting the vinyl ether bond of plasmalogens utilizing a cell-free system. Accordingly, the present experiments were designed to show that α-chloro fatty aldehydes are produced by activated neutrophils and to determine their physiologic effects. A sensitive gas chromatography-mass spectrometry technique was developed to detect pentafluorobenzyl oximes of α-chloro fatty aldehydes utilizing negative ion chemical ionization. Phorbol 12-myristate 13-acetate activation of neutrophils resulted in the production of both 2-chlorohexadecanal and 2- chlorooctadecanal through a myeloperoxidase-dependent mechanism that likely involved the targeting of both 16 and 18 carbon vinyl ether-linked aliphatic groups present in the sn-1 position of neutrophil plasmalogens. 2-Chlorohexadecanal was also produced by fMLP-treated neutrophils. Additionally, reactive chlorinating species released from activated neutrophils targeted endothelial cell plasmalogens resulting in 2-chlorohexadecanal production. Physiologically relevant concentrations of 2-chlorohexadecanal induced neutrophil chemotaxisin vitro suggesting that α-chloro fatty aldehydes may have a role in neutrophil recruitment. Taken together, these studies demonstrate for the first time a novel biochemical mechanism that targets the vinyl ether bond of plasmalogens during neutrophil activation resulting in the production of α-chloro fatty aldehydes that may enhance the recruitment of neutrophils to areas of active inflammation.
- Published
- 2002
19. Reactive Brominating Species Produced by Myeloperoxidase Target the Vinyl Ether Bond of Plasmalogens
- Author
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David A. Ford, Carolyn J. Albert, Jan R. Crowley, Arun K. Thukkani, and Fong-Fu Hsu
- Subjects
biology ,Plasmalogen ,Hypochlorous acid ,Sodium ,Phospholipid ,chemistry.chemical_element ,Cell Biology ,Vinyl ether ,Biochemistry ,chemistry.chemical_compound ,Lysophosphatidylcholine ,Membrane ,chemistry ,Myeloperoxidase ,biology.protein ,medicine ,Organic chemistry ,Molecular Biology ,medicine.drug - Abstract
Plasmalogens are a phospholipid molecular subclass that are enriched in the plasma membrane of many mammalian cells. The present study demonstrates that reactive brominating species produced by myeloperoxidase, as well as activated neutrophils, attack the vinyl ether bond of plasmalogens. Reactive brominating species produced by myeloperoxidase target the vinyl ether bond of plasmalogens, resulting in the production of a neutral lipid and lysophosphatidylcholine. Gas chromatography-mass spectrometry and proton NMR analyses of this neutral lipid demonstrated that it was 2-bromohexadecanal (2-BrHDA). In comparison to myeloperoxidase-generated reactive chlorinating species, reactive brominating species attacked the plasmalogen vinyl ether bond at neutral pH. In the presence of a 20-fold molar excess of NaCl compared with NaBr, myeloperoxidase-derived reactive halogenating species favored the production of 2-BrHDA over that of 2-chlorohexadecanal. Additionally, 2-BrHDA was preferentially produced from plasmalogen treated with hypochlorous acid in the presence of NaBr. The potential physiological significance of this pathway was suggested by the demonstration that both 2-BrHDA and 2-bromooctadecanal were produced by PMA-stimulated neutrophils. Taken together, the present studies demonstrate the targeting of the vinyl ether bond of plasmalogens by the reactive brominating species produced by myeloperoxidase and by activated neutrophils, resulting in the production of novel brominated fatty aldehydes.
- Published
- 2002
20. Reactive Chlorinating Species Produced by Myeloperoxidase Target the Vinyl Ether Bond of Plasmalogens
- Author
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Arun K. Thukkani, David A. Ford, Jan R. Crowley, Fong-Fu Hsu, and Carolyn J. Albert
- Subjects
chemistry.chemical_classification ,Hypochlorous acid ,Plasmalogen ,Electrospray ionization ,Cell Biology ,Vinyl ether ,Biochemistry ,Aldehyde ,Thin-layer chromatography ,chemistry.chemical_compound ,Fatty aldehyde ,chemistry ,polycyclic compounds ,medicine ,Organic chemistry ,Derivatization ,Molecular Biology ,medicine.drug - Abstract
Plasmalogens contain a vinyl ether bond linking the sn-1 aliphatic chain to the glycerol backbone of this predominant phospholipid molecular subclass, which is found in many mammalian tissues. The present study demonstrates that the vinyl ether bond of plasmalogens is a molecular target of the reactive chlorinating species produced by myeloperoxidase. Analysis by thin layer chromatography revealed that reactive chlorinating species produced by myeloperoxidase target the vinyl ether bond of the plasmalogen, lysoplasmenylcholine (1-O-hexadec-1′-enyl-sn-glycero-3-phosphorylcholine), resulting in the production of a neutral lipid. Capillary gas chromatographic analyses demonstrated that the neutral lipid generated from lysoplasmenylcholine was neither hexadecanal nor did it contain masked hexadecanal (i.e. the vinyl ether) because the dimethyl acetal of hexadecanal produced by acid methanolysis derivatization was no longer present. Electrospray ionization mass spectrometry of the myeloperoxidase-generated neutral lipid product was consistent with the production of a 16-carbon fatty aldehyde containing one chlorine atom. Furthermore, proton NMR analysis indicated that this neutral lipid product was a 2-chloro-fatty aldehyde. Additional structural analysis of this neutral lipid by gas chromatography-mass spectrometry of the underivatized product as well as its pentafluorobenzyl oxime-derivative product was consistent with the neutral lipid being 2-chlorohexadecanal. The reactive chlorinating species, hypochlorous acid and chlorine gas, both attacked the vinyl ether bond of lysoplasmenylcholine resulting in the production of 2-chlorohexadecanal. The production of 2-chlorohexadecanal was dependent on the presence of the plasmalogen masked aldehyde (i.e. the vinyl ether) in the substrate because the free fatty aldehyde, hexadecanal, was not converted to 2-chlorohexadecanal by the reactive chlorinating species generated by myeloperoxidase. Taken together, the present studies demonstrate for the first time the targeting of the vinyl ether bond of plasmalogens by the reactive chlorinating species produced by myeloperoxidase resulting in the production of novel chlorinated fatty aldehydes.
- Published
- 2001
21. Induction of the Peroxisomal Glycerolipid-synthesizing Enzymes during Differentiation of 3T3-L1 Adipocytes
- Author
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Nahid Hemati, Amiya K. Hajra, Arun K. Das, Leslie K. Larkins, Robin L. Erickson, and Ormond A. MacDougald
- Subjects
chemistry.chemical_classification ,ATP synthase ,biology ,Cell Biology ,Peroxisome ,Biochemistry ,chemistry.chemical_compound ,Enzyme ,chemistry ,DHAP ,biology.protein ,Glycerol ,Specific activity ,Cell fractionation ,Molecular Biology ,Dihydroxyacetone phosphate - Abstract
The glycerophosphate backbone for triglyceride synthesis is commonly believed to be created through the conversion of dihydroxyacetone phosphate (DHAP) by glycerophosphate dehydrogenase (GPD) to sn-glycerol 3-phosphate (GP), which is then converted by glycerophosphate acyltransferase (GPAT) to 1-acyl-GP. Consistent with this, GPD and GPAT are highly induced during differentiation of mouse 3T3-L1 preadipocytes. While the acyl dihydroxyacetone phosphate (acyl-DHAP) pathway for glycerolipid synthesis is commonly believed to be involved only in glycerol ether lipid synthesis, we report here that during conversion of 3T3-L1 preadipocytes to adipocytes, the specific activity of peroxisomal DHAP acyltransferase (DHAPAT) is increased by 9-fold in 6 days, while acyl-DHAP:NADPH reductase is induced by 5-fold. A parallel increase in the catalase (the peroxisomal marker enzyme) activity is also seen. In contrast, the specific activity of alkyl-DHAP synthase, the enzyme catalyzing the synthesis of the ether bond, is decreased by 60% during the same period. Unlike microsomal GPAT, the induced DHAPAT is found to have high activity at pH 5.5 and is resistant to inhibition by sulfhydryl agents, heat, and proteolysis. On subcellular fractionation, DHAPAT is found to be associated with microperoxisomes whereas GPAT activity is mainly present in microsomes. Northern blot analyses reveal that induction of DHAPAT can be largely explained through increases in DHAPAT mRNA. A comparison of microsomal and peroxisomal glycerolipid synthetic pathways, usingd-[3-3H, U-14C]glucose as the precursor of the lipid glycerol backbone shows that about 40–50% of triglyceride is synthesized via the acyl-DHAP pathway. These results indicate that the acyl-DHAP pathway is important not only for the synthesis of ether lipids, but also for the synthesis of triacylglycerol and other non-ether glycerolipids.
- Published
- 2000
22. Expression of α2,8/2,9-Polysialyltransferase fromEscherichia coli K92
- Author
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Kathryn M. Koeller, Gwo-Jenn Shen, Masayuki Izumi, Chi-Huey Wong, and Arun K. Datta
- Subjects
chemistry.chemical_classification ,Gel electrophoresis ,Lysis ,Cell Biology ,Biology ,Polysaccharide ,medicine.disease_cause ,Biochemistry ,Molecular biology ,Gene product ,Blot ,Enzyme ,chemistry ,medicine ,Molecular Biology ,Escherichia coli ,Histidine - Abstract
The capsular polysaccharide of Escherichia coli K92 contains alternating -8-NeuAcα2- and -9-NeuAcα2- linkages. The enzyme catalyzing this polymerizing reaction has been cloned from the genomic DNA of E. coli K92. The 1.2-kilobase polymerase chain reaction fragment was subcloned in pRSET vector and the protein was expressed in the BL21(DE3) strain ofE. coli with a hexameric histidine at its N-terminal end. The enzyme was isolated in the supernatant after lysis of the cells and fractionated by ultracentrifugation. Western blotting using anti-histidine antibody showed the presence of a band that migrated at about 47.5 kDa on both reducing and nonreducing SDS-polyacrylamide gel electrophoresis, indicating a monomeric enzyme. Among the carbohydrate acceptors tested, N-acetylneuraminic acid and the gangliosides GD3 and GQ1b were preferred substrates. The cell-free enzyme reaction products obtained were characterized by NMR and mass spectrometry, which indicated the presence of both α2,9- and α2,8-linked polysialyl structure. The K92 neuS gene was used to transform the K1 strain ofE. coli, the capsule of which contains only -8-NeuAcα2- linkages. Analysis of the polysaccharides isolated from these transformed cells is consistent with the presence of both -8-NeuAcα2- and -9-NeuAcα2- linkages. Our results suggest that theneuS gene product of E. coli K92 catalyzes the synthesis of polysialic acid with α2,9- and α2,8-linkages in vitro and in vivo.
- Published
- 1999
23. Engagement of Gab1 and Gab2 in Erythropoietin Signaling
- Author
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Arun K. Sharma, Taolin Yi, Stephen T. Sawyer, Yazan Alsayed, Amittha Wickrema, Toshio Hirano, Shahab Uddin, Sarfraz Ahmad, Keigo Nishada, Masahiko Hibi, Leonidas C. Platanias, Gerald Krystal, and Fei Chen
- Subjects
Protein Tyrosine Phosphatase, Non-Receptor Type 11 ,GAB2 ,Biology ,SH2 domain ,Biochemistry ,Cell Line ,Phosphatidylinositol 3-Kinases ,Growth factor receptor ,hemic and lymphatic diseases ,Receptors, Erythropoietin ,medicine ,Humans ,Phosphorylation ,Phosphotyrosine ,Receptor ,Erythropoietin ,Molecular Biology ,SOCS2 ,Adaptor Proteins, Signal Transducing ,Reverse Transcriptase Polymerase Chain Reaction ,Protein Tyrosine Phosphatase, Non-Receptor Type 6 ,Intracellular Signaling Peptides and Proteins ,Cell Biology ,Hematopoietic Stem Cells ,Phosphoproteins ,Erythropoietin receptor ,Kinetics ,biology.protein ,Protein Tyrosine Phosphatases ,Signal Transduction ,medicine.drug - Abstract
Several signaling cascades are activated during engagement of the erythropoietin receptor to mediate the biological effects of erythropoietin. The members of the insulin receptor substrate (IRS) family of proteins play a central role in signaling for various growth factor receptors and cytokines by acting as docking proteins for the SH2 domains of signaling elements, linking cytokine receptors to diverse downstream pathways. In the present study we provide evidence that the recently cloned IRS-related proteins, Gab1 and Gab2, of the Gab family of proteins, are rapidly phosphorylated on tyrosine during erythropoietin treatment of erythropoietin-responsive cells and provide docking sites for the engagement of the SHP2 phosphatase and the p85 subunit of the phosphatidylinositol 3′-kinase. Furthermore, our data show that Gab1 is the primary IRS-related protein activated by erythropoietin in primary erythroid progenitor cells. In studies to identify the erythropoietin receptor domains required for activation of Gab proteins, we found that tyrosines 425 and 367 in the cytoplasmic domain of the erythropoietin receptor are required for the phosphorylation of Gab2. Taken together, our data demonstrate that Gab proteins are engaged in erythropoietin signaling to mediate downstream activation of the SHP2 and phosphatidylinositol 3′-kinase pathways and possibly participate in the generation of the erythropoietin-induced mitogenic responses.
- Published
- 1999
24. Fucosylation of Disaccharide Precursors of Sialyl LewisX Inhibit Selectin-mediated Cell Adhesion
- Author
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K S Rostand, Arun K. Sarkar, Jeffrey D. Esko, Rakesh K. Jain, and Khushi L. Matta
- Subjects
Glycoconjugate ,Molecular Sequence Data ,Lewis X Antigen ,Oligosaccharides ,Disaccharides ,Biochemistry ,Fucose ,Mice ,chemistry.chemical_compound ,Lewis Blood Group Antigens ,Cell Adhesion ,Tumor Cells, Cultured ,Animals ,Humans ,Sialyl Lewis X Antigen ,Cell adhesion ,Molecular Biology ,Chromatography, High Pressure Liquid ,Fucosylation ,chemistry.chemical_classification ,biology ,Lectin ,Acetylation ,Mannosamine ,Cell Biology ,Sialic acid ,Carbohydrate Sequence ,Models, Chemical ,chemistry ,Sialic Acids ,biology.protein ,Endothelium, Vascular ,E-Selectin ,Selectin - Abstract
We showed previously that HL-60 and F9 mouse embryonal carcinoma cells will take up and deblock peracetylated Galbeta1-4GlcNAcbeta-O-naphthalenemethanol (Galbeta1-4GlcNAc-NM) and use the disaccharide as a primer of oligosaccharide chains (Sarkar, A. K., Fritz, T. A., Taylor, W. H., and Esko, J. D. (1995) Proc. Natl. Acad. Sci. U. S. A. 92, 3323-3327). We now report that another disaccharide, acetylated GlcNAcbeta1-3Gal-naphthalenemethanol (GlcNAcbeta1-3Gal-NM), has even greater potency and that both compounds will inhibit sialyl LewisX (sLex)-dependent cell adhesion. When fed to U937 cells, acetylated forms of Galbeta1-4GlcNAc-NM and GlcNAcbeta1-3Gal-NM primed oligosaccharides in a dose-dependent manner. Analysis of compounds assembled on Galbeta1-4GlcNAc-NM showed only one product, namely Galbeta1-4(Fucalpha1-3)GlcNAc-NM. In contrast, GlcNAcbeta1-3Gal-NM generated Galbeta1-4GlcNAcbeta1-3Gal-NM, Galbeta1-4(Fucalpha1-3)GlcNAcbeta1-3Gal-NM, NeuAcalpha2-3Galbeta1-4GlcNAcbeta1-3Gal-NM, and NeuAcalpha2-3Galbeta1-4(Fucalpha1-3)GlcNAcbeta1- 3Gal-NM. Both compounds decreased the incorporation of [3H]fucose into cellular glycoconjugates, without affecting the incorporation of [3H]mannosamine, a precursor of sialic acid residues. Moreover, the overall extent of sialylation was not affected based on the reactivity of cells to fluorescein isothiocyanate-conjugated Maackia amurensis lectin. Priming inhibited expression of sLex on cell surface glycoconjugates, which reduced E-selectin-dependent cell adhesion to tumor necrosis factor-alpha-activated human umbilical vein endothelial cells. GlcNAcbeta1-3Gal-NM and Galbeta1-4GlcNAc-NM represent starting points for making enzyme-specific, site-directed inhibitors of glycosyltransferases that could act in living cells.
- Published
- 1997
25. Calpain Expression in Lymphoid Cells
- Author
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Jean-Michel Goust, Naren L. Banik, Edward L. Hogan, Ernest Barbosa, Rajendra V. Deshpande, and Arun K. Chakrabarti
- Subjects
Messenger RNA ,Calpain ,Cell Biology ,Biology ,Cycloheximide ,Biochemistry ,Peripheral blood mononuclear cell ,Molecular biology ,chemistry.chemical_compound ,chemistry ,Cell culture ,Extracellular ,biology.protein ,Protein biosynthesis ,Cell activation ,Molecular Biology - Abstract
Although calpain is ubiquitously present in human tissues and is thought to play a role in demyelination, its activity is very low in resting normal lymphocytes. To determine the nature of calpain expression at the mRNA and protein levels in human lymphoid cells, we studied human T lymphocytic, B lymphocytic, and monocytic lines as well as peripheral blood mononuclear cells. Stimulation of cells with the phorbol ester phorbol myristate acetate and the calcium ionophore A23187 resulted in increased calpain mRNA and protein expression. Calpain mRNA expression is also increased in human T cells stimulated with anti-CD3. A dissociation between the increases of RNA and protein suggested that calpain could be released from the cells; the subsequent experiments showed its presence in the extracellular environment. 5,6-Dichloro-1b-D-ribofuranosylbenzimidazole, a reversible inhibitor of mRNA synthesis, reduced calpain mRNA levels by 50-67% and protein levels by 72-91%. Its removal resulted in resumption of both calpain mRNA and protein synthesis. Cycloheximide, a translational inhibitor, reduced calpain protein levels by 77-81% and calpain mRNA levels by 96% in activated THP-1 cells. Interferon-γ induced calpain mRNA and protein in U-937 and THP-1 cells. Dexamethasone increased mRNA expression in THP-1 cells. Our results indicate that activation of lymphoid cells results in de novo synthesis and secretion of calpain.
- Published
- 1995
26. The Sialyltransferase 'Sialylmotif' Participates in Binding the Donor Substrate CMP-NeuAc
- Author
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Arun K. Datta and James C. Paulson
- Subjects
Sialyltransferase ,Molecular Sequence Data ,Mutant ,Substrate analog ,Biochemistry ,chemistry.chemical_compound ,Animals ,Nucleotide ,Amino Acid Sequence ,Cloning, Molecular ,beta-D-Galactoside alpha 2-6-Sialyltransferase ,Molecular Biology ,Conserved Sequence ,chemistry.chemical_classification ,Alanine ,Binding Sites ,Base Sequence ,biology ,Wild type ,Cytidine ,Cell Biology ,Oligonucleotides, Antisense ,Molecular biology ,Recombinant Proteins ,Sialyltransferases ,Rats ,Amino acid ,Kinetics ,chemistry ,Multigene Family ,Cytidine Monophosphate N-Acetylneuraminic Acid ,Mutagenesis, Site-Directed ,biology.protein - Abstract
All members of the sialyltransferase gene family cloned to date contain a conserved region, the "sialylmotif," consisting of 48-49 amino acids in the center of the coding sequence. To investigate the function of this motif, mutant constructs of the Gal beta 1,4GlcNAc alpha 2,6-sialyltransferase were designed by site-directed mutagenesis, replacing 11 individual conserved amino acids with alanine. Each of the mutants was expressed in COS-1 cells, and eight of these retained sialyltransferase activity, allowing comparison of their enzymatic properties with that of the wild type enzyme. Kinetic analysis showed that six of eight mutants had a 3-12-fold higher Km for the donor substrate CMP-NeuAc relative to the wild type enzyme, while the Km values for the acceptor substrate were within 0.5-1.2-fold of the wild type for all eight mutants evaluated. The Ki of the donor substrate analog CDP was also evaluated for the recombinant sialyltransferase with the Val to Ala mutation at residue 220, which produced a 6-fold increase in Km of CMP-NeuAc. A corresponding increase in Ki of 3.4-fold was observed for CDP, indicating a decreased affinity for the cytidine nucleotide. Taken together, these results suggest that the conserved sialylmotif in the sialyltransferase gene family participates in the binding of the common donor substrate, CMP-NeuAc.
- Published
- 1995
27. Nuclear Factor κ B Functions as a Negative Regulator for the Rat Androgen Receptor Gene and NF- κ B Activity Increases during the Age-dependent Desensitization of the Liver
- Author
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Chung S. Song, Bandana Chatterjee, Prakash C. Supakar, Arun K. Roy, and Myeong H. Jung
- Subjects
Male ,Aging ,Steroid hormone receptor ,Molecular Sequence Data ,Repressor ,Biology ,Biochemistry ,Cell Line ,Transcriptional regulation ,Animals ,Enhancer ,Molecular Biology ,Transcription factor ,Regulation of gene expression ,Reporter gene ,Base Sequence ,NF-kappa B ,Cell Biology ,Molecular biology ,Rats, Inbred F344 ,Rats ,Androgen receptor ,Gene Expression Regulation ,Liver ,Receptors, Androgen ,Protein Binding - Abstract
Transcriptional regulation of the steroid hormone receptor genes plays a central role in temporal changes of target cell sensitivity during development, maturation, and aging. Sequence-specific DNA-protein interactions mediate these regulatory functions. Progressive 5' deletion of the rat androgen receptor (rAR) gene immediately beyond the -572 base pair (bp) region causes a marked increase in its promoter activity. DNase I footprinting with nuclear proteins revealed a protected area encompassing -574- to -554-bp positions that begins with a perfectly palindromic nuclear factor kappa B (NF-kappa B) motif. Electrophoretic mobility shift analyses (EMSA) showed that the decameric rAR NF-kappa B site at positions -574 to -565 cross-competes with the authentic kappa immunoglobulin light chain enhancer for specific protein binding. Supershift with specific antibodies to NF-kappa B subunits confirmed that the two retarded bands observed in the EMSA with the labeled rAR probe are due to p50/p65 and p50/p50 dimers of the NF-kappa B/Rel proteins. Fragments of rAR promoter with either deletion or point mutation of the NF-kappa B site are found to be about 2- to 3-fold more effective as compared to the wild type control in driving a heterologous reporter gene in cellulo. Thus, unlike most other known cases, NF-kappa B acts as a negative regulator for the rAR gene. The physiological relevance of this repressor function is evident from a 10-fold increase in the p50/p50 form of the NF-kappa B activity in the liver of aged rats exhibiting hepatic androgen desensitization. The newly identified repressor element is a rare example of a naturally occurring perfect palindromic binding motif for the NF-kappa B/Rel family of transcription factors. This repressor factor and the positively acting age-dependent factor, ADF, described earlier (Supakar, P. C., Song, C. S., Jung, M. H., Slomczynska, M. A., Kim, J.-M., Vellanoweth, R. L., Chatterjee, B.Roy, A. K. (1993) J. Biol. Chem. 268, 26400-26408) function to coordinate the tissue-specific down-regulation of the rAR gene during aging.
- Published
- 1995
28. Biosynthesis of heparan sulfate on beta-D-xylosides depends on aglycone structure
- Author
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Timothy A. Fritz, Jeffrey D. Esko, Arun K. Sarkar, and Fulgentius N. Lugemwa
- Subjects
Stereochemistry ,Chinese hamster ovary cell ,Hamster ,Cell Biology ,Heparan sulfate ,Xylose ,Biochemistry ,Xyloside ,Glycosaminoglycan ,chemistry.chemical_compound ,Aglycone ,chemistry ,Biosynthesis ,Molecular Biology - Abstract
We have reported that 3-estradiol-beta-D-xyloside primes heparan sulfate synthesis in Chinese hamster ovary cells and that the proportion of heparan sulfate made rises with increasing concentration of xyloside (Lugemwa, F.N. and Esko, J.D. (1991) J. Biol. Chem. 266, 6674-6677). Using estradiol as a guide, we varied the structure of the aglycone and showed that beta-D-xylosides containing two fused aromatic rings efficiently prime heparan sulfate. Thus, 2-naphthol-beta-D-xyloside primed heparan sulfate at low dose (
- Published
- 1994
29. A novel regulatory element associated with age-dependent expression of the rat androgen receptor gene
- Author
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Myeong H. Jung, Prakash C. Supakar, Arun K. Roy, Chung-Seog Song, Bandana Chatterjee, Maria Slomczynska, Robert L. Vellanoweth, and Jin Man Kim
- Subjects
Genetics ,medicine.drug_class ,Point mutation ,Promoter ,macromolecular substances ,Cell Biology ,Biology ,Androgen ,Biochemistry ,Androgen receptor ,Regulatory sequence ,Gene expression ,medicine ,Molecular Biology ,Transcription factor ,Function (biology) - Abstract
A large body of evidence indicates that the genetic program of aging has co-evolved with the sexual mode of reproduction (Partridge, L., and Barton, N. H. (1993) Nature 362, 305-311). Age-dependent changes in target cell sensitivity to reproductive hormones can be considered part of this evolutionary linkage. Here we describe a novel regulatory element in the rat androgen receptor (AR) gene promoter associated with its age-dependent expression in the liver. This element consists of two (19 and 25 base pairs) contiguous sites, one specifically binding an Age-dependent Factor (ADF) and the other an Associated Factor (AF). Both deletion and point mutations of the ADF site result in about a 5-fold decline in the AR promoter function. Unlike AF, which is relatively tissue specific, ADF appears to be ubiquitous. The ubiquitous and evolutionarily conserved nature of ADF suggests a fundamental role of this novel transcription factor in programmed gene expression.
- Published
- 1993
30. Both potential dolichol recognition sequences of hamster GlcNAc-1-phosphate transferase are necessary for normal enzyme function
- Author
-
Mark A. Lehrman and Arun K. Datta
- Subjects
chemistry.chemical_classification ,animal structures ,Mutant ,Hamster ,Cell Biology ,Tunicamycin ,Biology ,Biochemistry ,chemistry.chemical_compound ,Dolichol ,Enzyme ,chemistry ,Microsome ,Transferase ,Binding site ,Molecular Biology - Abstract
A potential dolichol recognition sequence (PDRS) with the 11-residue consensus F-I/V-X-F/Y-X-X-I-P-F-X-F/Y can be found in each of five microsomal enzymes that interact with dolichol or a dolichol derivative. However, no direct evidence demonstrating a role for the PDRSs has been reported. Hamster UDP-GlcNAc:dolichol phosphate N-acetylglucosamine-1-phosphate transferase (GPT) differs from the other enzymes by having two PDRSs. Stable CHO-K1 transfectants were created that expressed elevated amounts of normal GPT, GPT with a scramble mutation at the first PDRS (nearest the amino terminus), or GPT with a triple alanine-replacement mutation at the second PDRS. The mutant enzymes had no detectable catalytic activity in vivo, but were fully capable of conferring cellular resistance to the GPT inhibitor tunicamycin. In vitro studies with membrane preparations confirmed that the mutant enzymes were catalytically inactive and also showed that their recovery in microsomes was diminished compared with normal enzyme. These data demonstrate that each PDRS of hamster GPT is necessary for normal enzyme function. The implications of these data for possible roles of the PDRSs are discussed.
- Published
- 1993
31. Ligand-induced Dimerization of Middle East Respiratory Syndrome (MERS) Coronavirus nsp5 Protease (3CLpro)
- Author
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Tomar, Sakshi, primary, Johnston, Melanie L., additional, St. John, Sarah E., additional, Osswald, Heather L., additional, Nyalapatla, Prasanth R., additional, Paul, Lake N., additional, Ghosh, Arun K., additional, Denison, Mark R., additional, and Mesecar, Andrew D., additional
- Published
- 2015
- Full Text
- View/download PDF
32. Characterization of a Drosophila Ortholog of the Cdc7 Kinase
- Author
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Stephenson, Robert, primary, Hosler, Marcus R., additional, Gavande, Navnath S., additional, Ghosh, Arun K., additional, and Weake, Vikki M., additional
- Published
- 2015
- Full Text
- View/download PDF
33. Biosynthesis of glycerolipid precursors in rat liver peroxisomes and their transport and conversion to phosphatidate in the endoplasmic reticulum
- Author
-
Arun K. Das, Amiya K. Hajra, and Shuichi Horie
- Subjects
Chromatography ,biology ,Endoplasmic reticulum ,Phospholipid ,Cell Biology ,Peroxisome ,Biochemistry ,Phosphatidate ,chemistry.chemical_compound ,chemistry ,Biosynthesis ,DHAP ,biology.protein ,Microsome ,lipids (amino acids, peptides, and proteins) ,Bovine serum albumin ,Molecular Biology - Abstract
The transport of glycerolipid intermediates, viz. palmitoyl dihydroxyacetone phosphate (DHAP) and lysophosphatidate from peroxisomes and their conversion to phosphatidate in endoplasmic reticulum (microsomes) were studied in cell-free systems. The lipids were biosynthesized from [32P]DHAP, palmitoyl-CoA, and freshly made rat liver peroxisomes and microsomes in the presence or absence of Mg2+, NADPH, and bovine serum albumin (BSA). After incubation, the soluble fraction and the membranes were separated, and the distribution of radioactive lipids in these fractions were determined. The results showed that palmitoyl-DHAP and lysophosphatidate were recovered in the supernatant when BSA was present or when BSA was absent, but Mg2+ was removed after incubation by chelation with EDTA (or ATP). At low optimum palmitoyl-CoA concentration or when palmitoyl-CoA was generated in peroxisomes, and in the absence of BSA, the biosynthesized keto ether and ester lipids and lysophosphatidate were similarly present in the supernatant. Phosphatidate, however, was always localized in the membranes. Further fractionation showed that phosphatidate was associated with the microsomes. The critical micellar concentrations of palmitoyl-DHAP and 1-palmitoyl-rac-glycerol 3-phosphate, under the incubation conditions used, were determined to be 58 and 70 microM, respectively. These results suggest that at physiological concentrations the biosynthesized lysolipids are water soluble, and therefore, a carrier protein is unnecessary for their transport. These lipids freely diffuse from peroxisomes to endoplasmic reticulum where they are converted to membrane-bound phosphatidate.
- Published
- 1992
34. Mutants in a macrophage-like cell line are defective in plasmalogen biosynthesis, but contain functional peroxisomes
- Author
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Shanthi Rangaswamy, Ann B. Moser, Paul B. Lazarow, Manuel J. Santos, Haya Herscovitz, Raphael A. Zoeller, Hugo W. Moser, William B. Rizzo, Arun K. Das, and Amiya K. Hajra
- Subjects
Plasmanylethanolamine desaturase ,Plasmalogen ,Chinese hamster ovary cell ,Mutant ,Cell Biology ,Biology ,Peroxisome ,Biochemistry ,chemistry.chemical_compound ,Biosynthesis ,chemistry ,DHAP ,Molecular Biology ,Dihydroxyacetone phosphate - Abstract
We have used a fluorescence-activated cytotoxicity protocol, 9-(1‘-pyrene)nonanol (P9OH)/UV selection (Morand, O. H., Allen, L.-A. H., Zoeller, R. A., and Raetz, C. R. H. (1990) Biochim. Biophys. Acta 1034, 132-141), to isolate a series of plasmalogen-deficient mutants in a murine, macrophage-like cell line, RAW 264.7. Three of these mutants, RAW.7, RAW.12, and RAW.108, displayed varying degrees of plasmalogen deficiency (48, 17, and 14% of wild-type levels, respectively), and all three mutants were deficient in peroxisomal dihydroxyacetone phosphate (DHAP) acyltransferase activity (5% of wild-type). Unlike previously described Chinese hamster ovary (CHO) cell mutants, the RAW mutants contained intact, functional, peroxisomes and normal levels of alkyl-DHAP synthase activity, a peroxisomal, membrane-bound enzyme. In RAW.7 and RAW.108 cells, the loss of peroxisomal DHAP acyltransferase is the primary lesion. RAW.12 displayed not only a deficiency in the DHAP acyltransferase activity, but also displayed a second lesion in the biosynthetic pathway, a deficiency in delta 1‘-desaturase activity (plasmanylethanolamine desaturase, EC 1.14.99.19), the final step in plasmenylethanolamine biosynthesis. The deficiencies expressed in the mutants represent unique lesions in plasmalogen biosynthesis. Since the RAW cell line is a macrophage-like responsive cell line, these mutants can be used to examine the role of plasmalogens in cellular functions such as arachidonic acid metabolism, prostaglandin synthesis, protein secretion, and signal transduction.
- Published
- 1992
35. Peroxisomal localization of acyl-coenzyme A reductase (long chain alcohol forming) in guinea pig intestine mucosal cells
- Author
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Keith Burdett, Amiya K. Hajra, Leslie K. Larkins, and Arun K. Das
- Subjects
chemistry.chemical_classification ,Differential centrifugation ,Cell Biology ,Reductase ,Biology ,Peroxisome ,Biochemistry ,chemistry.chemical_compound ,Enzyme ,chemistry ,Acyltransferase ,Microbody ,Cell fractionation ,Molecular Biology ,Dihydroxyacetone phosphate - Abstract
Upon differential centrifugation of guinea pig intestine mucosal cells homogenate, fatty acyl-CoA:NADPH oxidoreductase (long chain alcohol forming) was found to be enriched in the light mitochondrial (L) fraction (sedimenting between 66,000 x g min and 500,000 x g min) which contained mainly mitochondria, lysosomes, and peroxisomes. Peroxisomes (marker enzymes: catalase and dihydroxyacetone phosphate acyltransferase) present in the L fraction were separated from other organelles in a Nycodenz density gradient centrifugation employing a vertical rotor. By comparing the distribution of acyl-CoA reductase with different marker enzymes in the gradient, it was concluded that this reductase is primarily localized in the microperoxisomes (microbodies). The topography of the membrane-bound enzyme in the isolated organelles was studied by checking its lability toward trypsin in the absence and presence of the detergent Triton X-100. The results suggested that acyl-CoA reductase is localized on the outer surface (cytosolic side) of microperoxisomal membrane.
- Published
- 1991
36. Regulation of the actin-activated ATPase activity of Acanthamoeba myosin II by copolymerization with phosphorylated and dephosphorylated peptides derived from the carboxyl-terminal end of the heavy chain
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Edward D. Korn, V. Sathyamoorthy, M. A. L. Atkinson, Blair Bowers, C Ganguly, and Arun K. Attri
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chemistry.chemical_classification ,Coiled coil ,Myosin light-chain kinase ,Peptide ,macromolecular substances ,Cell Biology ,Biology ,Biochemistry ,Serine ,Myosin head ,chemistry ,Myosin ,Phosphorylation ,Molecular Biology ,Actin - Abstract
Myosin II from Acanthamoeba castellanii is a conventional myosin composed of two heavy chains and two pairs of light chains. The amino-terminal approximately 90 kDa of each heavy chain form a globular head that contains the ATPase site and an ATP-sensitive actin-binding site. The carboxyl-terminal approximately 80 kDa of both heavy chains interact to form a coiled coil, helical rod (through which the molecules self-associate into bipolar filaments) ending in a short nonhelical tailpiece. Phosphorylation of 3 serine residues at the tip of the tail (at positions 11, 16, and 21 from the carboxyl terminus) inactivates the actin-activated Mg2(+)-ATPase activity of myosin II filaments. Previous work had indicated that the activity of each myosin II molecule in a filament reflects the global state of phosphorylation of the filament rather than the phosphorylation state of the molecule itself. We have now purified the approximately 28-kDa carboxyl-terminal region of the heavy chain lacking the last two phosphorylation sites, and we have shown that this peptide copolymerizes with and regulates the actin-activated Mg2(+)-ATPase activities of native dephosphorylated and phosphorylated myosin II. It can be concluded from these studies that the biologically relevant enzymatic activity of myosin II is regulated by a phosphorylation-dependent conformational change in the myosin filaments.
- Published
- 1990
37. Benzothiazinones Mediate Killing of Corynebacterineae by Blocking Decaprenyl Phosphate Recycling Involved in Cell Wall Biosynthesis
- Author
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Grover, Shipra, primary, Alderwick, Luke J., additional, Mishra, Arun K., additional, Krumbach, Karin, additional, Marienhagen, Jan, additional, Eggeling, Lothar, additional, Bhatt, Apoorva, additional, and Besra, Gurdyal S., additional
- Published
- 2014
- Full Text
- View/download PDF
38. Biosynthesis, Characterization, and Efficacy in Retinal Degenerative Diseases of Lens Epithelium-derived Growth Factor Fragment (LEDGF1–326), a Novel Therapeutic Protein
- Author
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Baid, Rinku, primary, Upadhyay, Arun K., additional, Shinohara, Toshimichi, additional, and Kompella, Uday B., additional
- Published
- 2013
- Full Text
- View/download PDF
39. Differential Arabinan Capping of Lipoarabinomannan Modulates Innate Immune Responses and Impacts T Helper Cell Differentiation
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Mishra, Arun K., primary, Alves, Joana E., additional, Krumbach, Karin, additional, Nigou, Jerome, additional, Castro, António G., additional, Geurtsen, Jeroen, additional, Eggeling, Lothar, additional, Saraiva, Margarida, additional, and Besra, Gurdyal S., additional
- Published
- 2012
- Full Text
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40. Low Temperature and Chemical Rescue Affect Molecular Proximity of ΔF508-Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) and Epithelial Sodium Channel (ENaC)
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Qadri, Yawar J., primary, Cormet-Boyaka, Estelle, additional, Rooj, Arun K., additional, Lee, William, additional, Parpura, Vladimir, additional, Fuller, Cathy M., additional, and Berdiev, Bakhrom K., additional
- Published
- 2012
- Full Text
- View/download PDF
41. Autophagosomal Membrane Serves as Platform for Intracellular Death-inducing Signaling Complex (iDISC)-mediated Caspase-8 Activation and Apoptosis
- Author
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Young, Megan M., primary, Takahashi, Yoshinori, additional, Khan, Osman, additional, Park, Sungman, additional, Hori, Tsukasa, additional, Yun, Jong, additional, Sharma, Arun K., additional, Amin, Shantu, additional, Hu, Chang-Deng, additional, Zhang, Jianke, additional, Kester, Mark, additional, and Wang, Hong-Gang, additional
- Published
- 2012
- Full Text
- View/download PDF
42. Glioma-specific Cation Conductance Regulates Migration and Cell Cycle Progression
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Rooj, Arun K., primary, McNicholas, Carmel M., additional, Bartoszewski, Rafal, additional, Bebok, Zsuzsanna, additional, Benos, Dale J., additional, and Fuller, Catherine M., additional
- Published
- 2012
- Full Text
- View/download PDF
43. Antagonists of Anaphase-promoting Complex (APC)-2-Cell Cycle and Apoptosis Regulatory Protein (CARP)-1 Interaction Are Novel Regulators of Cell Growth and Apoptosis
- Author
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Puliyappadamba, Vineshkumar Thidil, primary, Wu, Wenjuan, additional, Bevis, Debra, additional, Zhang, Liyue, additional, Polin, Lisa, additional, Kilkuskie, Robert, additional, Finley, Russell L., additional, Larsen, Scott D., additional, Levi, Edi, additional, Miller, Fred R., additional, Wali, Anil, additional, and Rishi, Arun K., additional
- Published
- 2011
- Full Text
- View/download PDF
44. Acceptor Substrate Discrimination in Phosphatidyl-myo-inositol Mannoside Synthesis
- Author
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Batt, Sarah M., primary, Jabeen, Talat, additional, Mishra, Arun K., additional, Veerapen, Natacha, additional, Krumbach, Karin, additional, Eggeling, Lothar, additional, Besra, Gurdyal S., additional, and Fütterer, Klaus, additional
- Published
- 2010
- Full Text
- View/download PDF
45. Expression of miR-33 from an SREBP2 Intron Inhibits Cholesterol Export and Fatty Acid Oxidation*
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Gerin, Isabelle, primary, Clerbaux, Laure-Alix, additional, Haumont, Olivier, additional, Lanthier, Nicolas, additional, Das, Arun K., additional, Burant, Charles F., additional, Leclercq, Isabelle A., additional, MacDougald, Ormond A., additional, and Bommer, Guido T., additional
- Published
- 2010
- Full Text
- View/download PDF
46. Arresting a Transient Receptor Potential (TRP) Channel
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Shukla, Arun K., primary, Kim, Jihee, additional, Ahn, Seungkirl, additional, Xiao, Kunhong, additional, Shenoy, Sudha K., additional, Liedtke, Wolfgang, additional, and Lefkowitz, Robert J., additional
- Published
- 2010
- Full Text
- View/download PDF
47. Proteolytic Cleavage of Human Acid-sensing Ion Channel 1 by the Serine Protease Matriptase
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Clark, Edlira B., primary, Jovov, Biljana, additional, Rooj, Arun K., additional, Fuller, Catherine M., additional, and Benos, Dale J., additional
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- 2010
- Full Text
- View/download PDF
48. A Mycobacterial Cyclic AMP Phosphodiesterase That Moonlights as a Modifier of Cell Wall Permeability
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Podobnik, Marjetka, primary, Tyagi, Richa, additional, Matange, Nishad, additional, Dermol, Urška, additional, Gupta, Arun K., additional, Mattoo, Rohini, additional, Seshadri, Kothandaraman, additional, and Visweswariah, Sandhya S., additional
- Published
- 2009
- Full Text
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49. Ubiquitination of β-Arrestin Links Seven-transmembrane Receptor Endocytosis and ERK Activation
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Shenoy, Sudha K., primary, Barak, Larry S., additional, Xiao, Kunhong, additional, Ahn, Seungkirl, additional, Berthouze, Magali, additional, Shukla, Arun K., additional, Luttrell, Louis M., additional, and Lefkowitz, Robert J., additional
- Published
- 2007
- Full Text
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50. Potent Inhibition of HIV-1 Replication by Novel Non-peptidyl Small Molecule Inhibitors of Protease Dimerization
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Koh, Yasuhiro, primary, Matsumi, Shintaro, additional, Das, Debananda, additional, Amano, Masayuki, additional, Davis, David A., additional, Li, Jianfeng, additional, Leschenko, Sofiya, additional, Baldridge, Abigail, additional, Shioda, Tatsuo, additional, Yarchoan, Robert, additional, Ghosh, Arun K., additional, and Mitsuya, Hiroaki, additional
- Published
- 2007
- Full Text
- View/download PDF
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