Publications by authors named "Eric S Wang"

17 Publications

  • Page 1 of 1

Selective Degradation of GSPT1 by Cereblon Modulators Identified via a Focused Combinatorial Library.

ACS Chem Biol 2020 10 28;15(10):2722-2730. Epub 2020 Sep 28.

Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, United States.

Cereblon (CRBN) is an E3 ligase adapter protein that can be reprogrammed by imide-class compounds such as thalidomide, lenalidomide, and pomalidomide to induce the degradation of neo-substrate proteins. In order to identify additional small molecule CRBN modulators, we implemented a focused combinatorial library approach where we fused an imide-based CRBN-binding pharmacophore to a heterocyclic scaffold, which could be further elaborated. We screened the library for CRBN-dependent antiproliferative activity in the multiple myeloma cell line MM1.S and identified five hit compounds. Quantitative chemical proteomics of hit compounds revealed that they induced selective degradation of GSPT1, a translation termination factor that is currently being explored as a therapeutic target for the treatment of acute myeloid leukemia. Molecular docking studies with CRBN and GSPT1 followed by analogue synthesis identified a possible hydrogen bond interaction with the central pyrimidine ring as a molecular determinant of hit compounds' selectivity. This study demonstrates that a focused combinatorial library design, phenotypic screening, and chemical proteomics can provide a suitable workflow to efficiently identify novel CRBN modulators.
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http://dx.doi.org/10.1021/acschembio.0c00520DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7843009PMC
October 2020

CDK7 Inhibition Potentiates Genome Instability Triggering Anti-tumor Immunity in Small Cell Lung Cancer.

Cancer Cell 2020 01 26;37(1):37-54.e9. Epub 2019 Dec 26.

Laura and Isaac Perlmutter Cancer Center, New York University Langone Medical Center, New York, NY 10016, USA. Electronic address:

Cyclin-dependent kinase 7 (CDK7) is a central regulator of the cell cycle and gene transcription. However, little is known about its impact on genomic instability and cancer immunity. Using a selective CDK7 inhibitor, YKL-5-124, we demonstrated that CDK7 inhibition predominately disrupts cell-cycle progression and induces DNA replication stress and genome instability in small cell lung cancer (SCLC) while simultaneously triggering immune-response signaling. These tumor-intrinsic events provoke a robust immune surveillance program elicited by T cells, which is further enhanced by the addition of immune-checkpoint blockade. Combining YKL-5-124 with anti-PD-1 offers significant survival benefit in multiple highly aggressive murine models of SCLC, providing a rationale for new combination regimens consisting of CDK7 inhibitors and immunotherapies.
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http://dx.doi.org/10.1016/j.ccell.2019.11.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7277075PMC
January 2020

Development of Dual and Selective Degraders of Cyclin-Dependent Kinases 4 and 6.

Angew Chem Int Ed Engl 2019 05 29;58(19):6321-6326. Epub 2019 Mar 29.

Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA.

Cyclin-dependent kinases 4 and 6 (CDK4/6) are key regulators of the cell cycle, and there are FDA-approved CDK4/6 inhibitors for treating patients with metastatic breast cancer. However, due to conservation of their ATP-binding sites, development of selective agents has remained elusive. Here, we report imide-based degrader molecules capable of degrading both CDK4/6, or selectively degrading either CDK4 or CDK6. We were also able to tune the activity of these molecules against Ikaros (IKZF1) and Aiolos (IKZF3), which are well-established targets of imide-based degraders. We found that in mantle cell lymphoma cell lines, combined IKZF1/3 degradation with dual CDK4/6 degradation produced enhanced anti-proliferative effects compared to CDK4/6 inhibition, CDK4/6 degradation, or IKZF1/3 degradation. In summary, we report here the first compounds capable of inducing selective degradation of CDK4 and CDK6 as tools to pharmacologically dissect their distinct biological functions.
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http://dx.doi.org/10.1002/anie.201901336DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7678623PMC
May 2019

Homolog-Selective Degradation as a Strategy to Probe the Function of CDK6 in AML.

Cell Chem Biol 2019 02 27;26(2):300-306.e9. Epub 2018 Dec 27.

CeMM Research Center for Molecular Medicine of the Austrian Academy of Science, Vienna, Austria. Electronic address:

The design of selective small molecules is often stymied by similar ligand binding pockets. Here, we report BSJ-03-123, a phthalimide-based degrader that exploits protein-interface determinants to achieve proteome-wide selectivity for the degradation of cyclin-dependent kinase 6 (CDK6). Pharmacologic CDK6 degradation targets a selective dependency of acute myeloid leukemia cells, and transcriptomics and phosphoproteomics profiling of acute degradation of CDK6 enabled dynamic mapping of its immediate role in coordinating signaling and transcription.
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http://dx.doi.org/10.1016/j.chembiol.2018.11.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6444916PMC
February 2019

Bruton tyrosine kinase degradation as a therapeutic strategy for cancer.

Blood 2019 02 13;133(9):952-961. Epub 2018 Dec 13.

Department of Cancer Biology, Dana-Farber Cancer Institute, Boston MA.

The covalent Bruton tyrosine kinase (BTK) inhibitor ibrutinib is highly efficacious against multiple B-cell malignancies. However, it is not selective for BTK, and multiple mechanisms of resistance, including the C481S-BTK mutation, can compromise its efficacy. We hypothesized that small-molecule-induced BTK degradation may overcome some of the limitations of traditional enzymatic inhibitors. Here, we demonstrate that BTK degradation results in potent suppression of signaling and proliferation in cancer cells and that BTK degraders efficiently degrade C481S-BTK. Moreover, we discovered DD-03-171, an optimized lead compound that exhibits enhanced antiproliferative effects on mantle cell lymphoma (MCL) cells in vitro by degrading BTK, IKFZ1, and IKFZ3 as well as efficacy against patient-derived xenografts in vivo. Thus, "triple degradation" may be an effective therapeutic approach for treating MCL and overcoming ibrutinib resistance, thereby addressing a major unmet need in the treatment of MCL and other B-cell lymphomas.
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http://dx.doi.org/10.1182/blood-2018-07-862953DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6396177PMC
February 2019

Development and Application of FASA, a Model for Quantifying Fatty Acid Metabolism Using Stable Isotope Labeling.

Cell Rep 2018 12;25(10):2919-2934.e8

Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, 615 Charles E. Young Drive East, Los Angeles, CA 90095, USA; Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine, University of California, Los Angeles, 615 Charles E. Young Drive East, Los Angeles, CA 90095, USA. Electronic address:

It is well understood that fatty acids can be synthesized, imported, and modified to meet requisite demands in cells. However, following the movement of fatty acids through the multiplicity of these metabolic steps has remained difficult. To better address this problem, we developed Fatty Acid Source Analysis (FASA), a model that defines the contribution of synthesis, import, and elongation pathways to fatty acid homeostasis in saturated, monounsaturated, and polyunsaturated fatty acid pools. Application of FASA demonstrated that elongation can be a major contributor to cellular fatty acid content and showed that distinct pro-inflammatory stimuli (e.g., Toll-like receptors 2, 3, or 4) specifically reprogram homeostasis of fatty acids by differential utilization of synthetic and elongation pathways in macrophages. In sum, this modeling approach significantly advances our ability to interrogate cellular fatty acid metabolism and provides insight into how cells dynamically reshape their lipidomes in response to metabolic or inflammatory signals.
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http://dx.doi.org/10.1016/j.celrep.2018.11.041DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6432944PMC
December 2018

Development of Highly Potent and Selective Steroidal Inhibitors and Degraders of CDK8.

ACS Med Chem Lett 2018 Jun 18;9(6):540-545. Epub 2018 Mar 18.

Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, United States.

Cortistatin A is a natural product isolated from the marine sponge Corticium simplex and was found to be a potent and selective inhibitor of CDK8. Many synthetic groups have reported total syntheses of Cortistatin A; however, these syntheses require between 16 and 30 steps and report between 0.012-2% overall yields, which is not amenable to large-scale production. Owing to similarities between the complex core of Cortistatin A and the simple steroid core, we initiated a campaign to design simple, more easily prepared CDK8 inhibitors based on a steroid scaffold that would be more convenient for large-scale synthesis. Herein, we report the discovery and optimization of JH-VIII-49, a potent and selective inhibitor of CDK8 with a simple steroid core that has an eight-step synthesis with a 33% overall yield, making it suitable for large-scale preparation. Using this scaffold, we then developed a bivalent small molecule degrader, JH-XI-10-02, that can recruit the E3 ligase CRL4 to promote the ubiquitination and proteosomal degradation of CDK8.
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http://dx.doi.org/10.1021/acsmedchemlett.8b00011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6004574PMC
June 2018

CDK4/6 Inhibition Augments Antitumor Immunity by Enhancing T-cell Activation.

Cancer Discov 2018 02 3;8(2):216-233. Epub 2017 Nov 3.

Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts.

Immune checkpoint blockade, exemplified by antibodies targeting the PD-1 receptor, can induce durable tumor regressions in some patients. To enhance the efficacy of existing immunotherapies, we screened for small molecules capable of increasing the activity of T cells suppressed by PD-1. Here, we show that short-term exposure to small-molecule inhibitors of cyclin-dependent kinases 4 and 6 (CDK4/6) significantly enhances T-cell activation, contributing to antitumor effects , due in part to the derepression of NFAT family proteins and their target genes, critical regulators of T-cell function. Although CDK4/6 inhibitors decrease T-cell proliferation, they increase tumor infiltration and activation of effector T cells. Moreover, CDK4/6 inhibition augments the response to PD-1 blockade in a novel organotypic tumor spheroid culture system and in multiple murine syngeneic models, thereby providing a rationale for combining CDK4/6 inhibitors and immunotherapies. Our results define previously unrecognized immunomodulatory functions of CDK4/6 and suggest that combining CDK4/6 inhibitors with immune checkpoint blockade may increase treatment efficacy in patients. Furthermore, our study highlights the critical importance of identifying complementary strategies to improve the efficacy of immunotherapy for patients with cancer. .
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http://dx.doi.org/10.1158/2159-8290.CD-17-0915DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5809273PMC
February 2018

Profiling of PD-1 Blockade Using Organotypic Tumor Spheroids.

Cancer Discov 2018 02 3;8(2):196-215. Epub 2017 Nov 3.

Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts.

systems that incorporate features of the tumor microenvironment and model the dynamic response to immune checkpoint blockade (ICB) may facilitate efforts in precision immuno-oncology and the development of effective combination therapies. Here, we demonstrate the ability to interrogate response to ICB using murine- and patient-derived organotypic tumor spheroids (MDOTS/PDOTS). MDOTS/PDOTS isolated from mouse and human tumors retain autologous lymphoid and myeloid cell populations and respond to ICB in short-term three-dimensional microfluidic culture. Response and resistance to ICB was recapitulated using MDOTS derived from established immunocompetent mouse tumor models. MDOTS profiling demonstrated that TBK1/IKKε inhibition enhanced response to PD-1 blockade, which effectively predicted tumor response Systematic profiling of secreted cytokines in PDOTS captured key features associated with response and resistance to PD-1 blockade. Thus, MDOTS/PDOTS profiling represents a novel platform to evaluate ICB using established murine models as well as clinically relevant patient specimens. Resistance to PD-1 blockade remains a challenge for many patients, and biomarkers to guide treatment are lacking. Here, we demonstrate feasibility of profiling of PD-1 blockade to interrogate the tumor immune microenvironment, develop therapeutic combinations, and facilitate precision immuno-oncology efforts. .
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http://dx.doi.org/10.1158/2159-8290.CD-17-0833DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5809290PMC
February 2018

An optimized method for measuring fatty acids and cholesterol in stable isotope-labeled cells.

J Lipid Res 2017 02 14;58(2):460-468. Epub 2016 Dec 14.

Departments of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095

Stable isotope labeling has become an important methodology for determining lipid metabolic parameters of normal and neoplastic cells. Conventional methods for fatty acid and cholesterol analysis have one or more issues that limit their utility for in vitro stable isotope-labeling studies. To address this, we developed a method optimized for measuring both fatty acids and cholesterol from small numbers of stable isotope-labeled cultured cells. We demonstrate quantitative derivatization and extraction of fatty acids from a wide range of lipid classes using this approach. Importantly, cholesterol is also recovered, albeit at a modestly lower yield, affording the opportunity to quantitate both cholesterol and fatty acids from the same sample. Although we find that background contamination can interfere with quantitation of certain fatty acids in low amounts of starting material, our data indicate that this optimized method can be used to accurately measure mass isotopomer distributions for cholesterol and many fatty acids isolated from small numbers of cultured cells. Application of this method will facilitate acquisition of lipid parameters required for quantifying flux and provide a better understanding of how lipid metabolism influences cellular function.
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http://dx.doi.org/10.1194/jlr.D069336DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5282944PMC
February 2017

Variation in Acceptable Child Discipline Practices by Child Age: Perceptions of Community Norms by Medical and Legal Professionals.

Behav Sci Law 2016 Jan;34(1):95-112

The University of Colorado School of Medicine, Aurora, CO, U.S.A.

Mandated child abuse reporters may judge specific disciplinary practices as unacceptable for young children, whereas child law professionals arbitrating allegations may be less inclusive. Do the views of these groups diverge, by child age, regarding discipline? Judgments of community norms across a wide range of children's ages were obtained from 380 medical and legal professionals. Because the Parent-Child Conflict Tactics Scale (PC-CTS) can be used to assess the epidemiology of child disciplinary behaviors and as a proxy to examine the incidence or prevalence of child abuse, the disciplinary practices described on the PC-CTS were presented as triggers for questions. Significant child age effects were found for disciplinary practices classified as "harsh." The consistencies between legal and medical professionals were striking. Both groups reflected changes in United States norms, as non-physical approaches were the most approved. We conclude that instruments estimating the prevalence of child maltreatment by parent-report should consider modifying how specific disciplinary practices are classified. Copyright © 2016 John Wiley & Sons, Ltd.
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http://dx.doi.org/10.1002/bsl.2237DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5831380PMC
January 2016

Limiting Cholesterol Biosynthetic Flux Spontaneously Engages Type I IFN Signaling.

Cell 2015 Dec 10;163(7):1716-29. Epub 2015 Dec 10.

Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA; Department of Pathology and Laboratory Medicine, University of California, Los Angeles, David Geffen School of Medicine, Los Angeles, CA 90095, USA. Electronic address:

Cellular lipid requirements are achieved through a combination of biosynthesis and import programs. Using isotope tracer analysis, we show that type I interferon (IFN) signaling shifts the balance of these programs by decreasing synthesis and increasing import of cholesterol and long chain fatty acids. Genetically enforcing this metabolic shift in macrophages is sufficient to render mice resistant to viral challenge, demonstrating the importance of reprogramming the balance of these two metabolic pathways in vivo. Unexpectedly, mechanistic studies reveal that limiting flux through the cholesterol biosynthetic pathway spontaneously engages a type I IFN response in a STING-dependent manner. The upregulation of type I IFNs was traced to a decrease in the pool size of synthesized cholesterol and could be inhibited by replenishing cells with free cholesterol. Taken together, these studies delineate a metabolic-inflammatory circuit that links perturbations in cholesterol biosynthesis with activation of innate immunity.
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http://dx.doi.org/10.1016/j.cell.2015.11.045DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4783382PMC
December 2015

Fas-Activated Mitochondrial Apoptosis Culls Stalled Embryonic Stem Cells to Promote Differentiation.

Curr Biol 2015 Dec 12;25(23):3110-8. Epub 2015 Nov 12.

Department of Pathology, University of California, San Francisco, San Francisco, CA 94143, USA; Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94143, USA; Diabetes Center, University of California, San Francisco, San Francisco, CA 94143, USA. Electronic address:

The intrinsic (mitochondrial) apoptotic pathway is a conserved cell death program crucial for eliminating superfluous, damaged, or incorrectly specified cells, and the multi-domain pro-death BCL-2 family proteins BAX and BAK are required for its activation. In response to internal damage or developmental signals, BAX and/or BAK permeabilize the mitochondrial outer membrane, resulting in cytochrome c release and activation of effector caspases such as Caspase-3 (Casp3). While the mitochondrial apoptotic pathway plays a critical role during late embryonic development in mammals, its role during early development remains controversial. Here, we show that Bax(-/-)Bak(-/-) murine embryonic stem cells (ESCs) display defects during the exit from pluripotency, both in culture and during teratoma formation. Specifically, we find that when ESCs are stimulated to differentiate, a subpopulation fails to do so and instead upregulates FAS in a p53-dependent manner to trigger Bax/Bak-dependent apoptosis. Blocking this apoptotic pathway prevents the removal of these poorly differentiated cells, resulting in the retention of cells that have not exited pluripotency. Taken together, our results provide further evidence for heterogeneity in the potential of ESCs to successfully differentiate and reveal a novel role for apoptosis in promoting efficient ESC differentiation by culling cells that are slow to exit pluripotency.
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http://dx.doi.org/10.1016/j.cub.2015.10.020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4703423PMC
December 2015

Allosteric inhibition of the IRE1α RNase preserves cell viability and function during endoplasmic reticulum stress.

Cell 2014 Jul 10;158(3):534-48. Epub 2014 Jul 10.

Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA; Diabetes Center, University of California, San Francisco, San Francisco, CA 94143, USA; Lung Biology Center, University of California, San Francisco, San Francisco, CA 94143, USA; California Institute for Quantitative Biosciences, University of California, San Francisco, San Francisco, CA 94143, USA. Electronic address:

Depending on endoplasmic reticulum (ER) stress levels, the ER transmembrane multidomain protein IRE1α promotes either adaptation or apoptosis. Unfolded ER proteins cause IRE1α lumenal domain homo-oligomerization, inducing trans autophosphorylation that further drives homo-oligomerization of its cytosolic kinase/endoribonuclease (RNase) domains to activate mRNA splicing of adaptive XBP1 transcription factor. However, under high/chronic ER stress, IRE1α surpasses an oligomerization threshold that expands RNase substrate repertoire to many ER-localized mRNAs, leading to apoptosis. To modulate these effects, we developed ATP-competitive IRE1α Kinase-Inhibiting RNase Attenuators-KIRAs-that allosterically inhibit IRE1α's RNase by breaking oligomers. One optimized KIRA, KIRA6, inhibits IRE1α in vivo and promotes cell survival under ER stress. Intravitreally, KIRA6 preserves photoreceptor functional viability in rat models of ER stress-induced retinal degeneration. Systemically, KIRA6 preserves pancreatic β cells, increases insulin, and reduces hyperglycemia in Akita diabetic mice. Thus, IRE1α powerfully controls cell fate but can itself be controlled with small molecules to reduce cell degeneration.
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http://dx.doi.org/10.1016/j.cell.2014.07.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4244221PMC
July 2014

IRE1α cleaves select microRNAs during ER stress to derepress translation of proapoptotic Caspase-2.

Science 2012 Nov 4;338(6108):818-22. Epub 2012 Oct 4.

Department of Pathology, University of California, San Francisco, San Francisco, CA 94143, USA.

The endoplasmic reticulum (ER) is the primary organelle for folding and maturation of secretory and transmembrane proteins. Inability to meet protein-folding demand leads to "ER stress," and activates IRE1α, an ER transmembrane kinase-endoribonuclease (RNase). IRE1α promotes adaptation through splicing Xbp1 mRNA or apoptosis through incompletely understood mechanisms. Here, we found that sustained IRE1α RNase activation caused rapid decay of select microRNAs (miRs -17, -34a, -96, and -125b) that normally repress translation of Caspase-2 mRNA, and thus sharply elevates protein levels of this initiator protease of the mitochondrial apoptotic pathway. In cell-free systems, recombinant IRE1α endonucleolytically cleaved microRNA precursors at sites distinct from DICER. Thus, IRE1α regulates translation of a proapoptotic protein through terminating microRNA biogenesis, and noncoding RNAs are part of the ER stress response.
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http://dx.doi.org/10.1126/science.1226191DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3742121PMC
November 2012

Adaptation of an ICAM-1-tropic enterovirus to the mouse respiratory tract.

J Virol 2011 Jun 30;85(11):5606-17. Epub 2011 Mar 30.

Division of Neurosurgery, Department of Surgery, Duke University Medical Center, Durham, North Carolina 27710, USA.

Respiratory tract (RT) infections by members of the enterovirus (EV) genus of the Picornaviridae family are the most frequent cause for the common cold and a major factor in the exacerbation of chronic pulmonary diseases. The lack of a practical small-animal model for these infections has obstructed insight into pathogenic mechanisms of the common cold and their role in chronic RT illness and has hampered preclinical evaluation of antiviral strategies. Despite significant efforts, it has been difficult to devise rodent models that exhibit viral replication in the RT. This is due mainly to well-known intracellular host restrictions of EVs with RT tropism in rodent cells. We report the evolution of variants of the common-cold-causing coxsackievirus A21, an EV with tropism for the human intercellular adhesion molecule 1 (hICAM-1), through serial passage in the lungs of mice transgenic for the hICAM-1 gene. This process was accompanied by multiple changes in the viral genome, suggesting exquisite adaptation of hICAM-1-tropic enteroviruses to the specific growth conditions within the RT. In vivo mouse RT-adapted, variant coxsackievirus A21 exhibited replication competence in the lungs of hICAM-1 transgenic mice, providing a basis for unraveling EV-host interactions in the mouse RT.
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http://dx.doi.org/10.1128/JVI.01502-10DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3094975PMC
June 2011

Reexamination of the cysteine residues in glucocerebrosidase.

FEBS Lett 2006 Jun 11;580(14):3391-4. Epub 2006 May 11.

Unit on Molecular Structures, Laboratory of Neurotoxicology, NIMH, NIH, DHHS, Bethesda, MD 20892, USA.

Glucocerebrosidase, the deficient enzyme in Gaucher disease, catalyzes the cleavage of the beta-glycosidic linkage of glucosylceramide. A previous study on the enzyme identified three disulfide bridges and a single sulfhydryl [Lee, Y., Kinoshita, H., Radke, G., Weiler, S., Barranger, J.A. and Tomich, J.M. (1995) Position of the sulfhydryl group and the disulfide bonds of human glucocerebrosidase. J. Protein Chem. 14(3), 127-137] but recent publication of the X-ray structure identifies only two disulfide bridges with three free sulfhydryls [Dvir, H., Harel, M., McCarthy, A.A., Toker, L., Silman, I., Futerman, A.H. and Sussman, J.L. (2003) X-ray structure of human acid-beta-glucosidase, the defective enzyme in Gaucher disease. EMBO. 4(7), 704-709]. Using chemical modifications, acid cleavage and enzymatic digestion methods, we report that three free sulfhydryls exist and that the remaining four cysteines form two disulfide bonds located within the first 25 amino-terminal residues, supporting the X-ray structure.
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http://dx.doi.org/10.1016/j.febslet.2006.04.096DOI Listing
June 2006