7 results on '"Dvorin J"'
Search Results
2. Plasmodium SEY1 is a novel druggable target that contributes to imidazolopiperazine mechanism of action.
- Author
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Winzeler E, Carolino K, De Souza ML, Chen D, Farre JC, Blauwkamp J, Absalon S, Ghidelli-Disse S, Morano A, Dvorin J, Lafuente-Monasterio MJ, and Gamo FJ
- Abstract
The precise mode of action of ganaplacide (KAF156), a phase III antimalarial candidate, remains elusive. Here we employ omics-based methods with the closely related chemical analog, GNF179, to search for potential Plasmodium targets. Ranking potential targets derived from chemical genetics and proteomic affinity chromatography methodologies identifies SEY1 , or Synthetic Enhancement of YOP1, which is predicted to encode an essential dynamin-like GTPase implicated in homotypic fusion of endoplasmic reticulum (ER) membranes. We demonstrate that GNF179 decreases Plasmodium SEY1 melting temperature. We further show that GNF179 binds to recombinant Plasmodium SEY1 and subsequently inhibits its GTPase activity, which is required for maintaining ER architecture. Using ultrastructure expansion microscopy, we find GNF179 treatment changes parasite ER and Golgi morphology. We also confirm that SEY1 is an essential gene in P. falciparum . These data suggest that SEY1 may contribute to the mechanism of action of imidazolopiperazines and is a new and attractive druggable target.
- Published
- 2024
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3. Atlas of Plasmodium falciparum intraerythrocytic development using expansion microscopy.
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Liffner B, Cepeda Diaz AK, Blauwkamp J, Anaguano D, Frölich S, Muralidharan V, Wilson DW, Dvorin J, and Absalon S
- Abstract
Apicomplexan parasites exhibit tremendous diversity in much of their fundamental cell biology, but study of these organisms using light microscopy is often hindered by their small size. Ultrastructural expansion microscopy (U-ExM) is a microscopy preparation method that physically expands the sample ~4.5x. Here, we apply U-ExM to the human malaria parasite Plasmodium falciparum during the asexual blood stage of its lifecycle to understand how this parasite is organized in three-dimensions. Using a combination of dye-conjugated reagents and immunostaining, we have catalogued 13 different P. falciparum structures or organelles across the intraerythrocytic development of this parasite and made multiple observations about fundamental parasite cell biology. We describe that the outer centriolar plaque and its associated proteins anchor the nucleus to the parasite plasma membrane during mitosis. Furthermore, the rhoptries, Golgi, basal complex, and inner membrane complex, which form around this anchoring site while nuclei are still dividing, are concurrently segregated and maintain an association to the outer centriolar plaque until the start of segmentation. We also show that the mitochondrion and apicoplast undergo sequential fission events while maintaining an association with the outer centriolar plaque during cytokinesis. Collectively, this study represents the most detailed ultrastructural analysis of P. falciparum during its intraerythrocytic development to date, and sheds light on multiple poorly understood aspects of its organelle biogenesis and fundamental cell biology., Competing Interests: COMPETING INTERESTS The authors declare no competing interests.
- Published
- 2023
- Full Text
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4. Phenotypic Screens Identify Genetic Factors Associated with Gametocyte Development in the Human Malaria Parasite Plasmodium falciparum.
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Chawla J, Goldowitz I, Oberstaller J, Zhang M, Pires CV, Navarro F, Sollelis L, Wang CCQ, Seyfang A, Dvorin J, Otto TD, Rayner JC, Marti M, and Adams JH
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- Animals, Humans, Plasmodium falciparum genetics, Mosquito Vectors genetics, Phenotype, Parasites, Malaria, Malaria, Falciparum parasitology, Culicidae
- Abstract
Transmission of the deadly malaria parasite Plasmodium falciparum from humans to mosquitoes is achieved by specialized intraerythrocytic sexual forms called gametocytes. Though the crucial regulatory mechanisms leading to gametocyte commitment have recently come to light, networks of genes that control sexual development remain to be elucidated. Here, we report a pooled-mutant screen to identify genes associated with gametocyte development in P. falciparum. Our results categorized genes that modulate gametocyte progression as hypoproducers or hyperproducers of gametocytes, and the in-depth analysis of individual clones confirmed phenotypes in sexual commitment rates and putative functions in gametocyte development. We present a new set of genes that have not been implicated in gametocytogenesis before and demonstrate the potential of forward genetic screens in isolating genes impacting parasite sexual biology, an exciting step toward the discovery of new antimalarials for a globally significant pathogen. IMPORTANCE Blocking human-to-vector transmission is an essential step toward malaria elimination. Gametocytes are solely responsible for achieving this transmission and represent an opportunity for therapeutic intervention. While these falciform-shaped parasite stages were first discovered in the 1880s, our understanding of the genetic determinants responsible for their formation and molecular mechanisms that drive their development is limited. In this work, we developed a scalable screening methodology with piggyBac mutants to identify genes that influence the development of gametocytes in the most lethal human malaria parasite, P. falciparum. By doing so, we lay the foundation for large-scale functional genomic studies specifically designed to address remaining questions about sexual commitment, maturation, and mosquito infection in P. falciparum. Such functional genetic screens will serve to expedite the identification of essential pathways and processes for the development of novel transmission-blocking agents., Competing Interests: The authors declare no conflict of interest.
- Published
- 2023
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5. Emergence of community-associated methicillin resistant Staphylococcus aureus in Hawaii, 2001-2003.
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Estivariz CF, Park SY, Hageman JC, Dvorin J, Melish MM, Arpon R, Coon P, Slavish S, Kim M, McDougal LK, Jensen B, McAllister S, Lonsway D, Killgore G, Effler PE, and Jernigan DB
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- Adolescent, Adult, Aged, Aged, 80 and over, Anti-Bacterial Agents pharmacology, Bacterial Toxins genetics, Child, Child, Preschool, Chromosomes, Bacterial genetics, Community-Acquired Infections microbiology, Electrophoresis, Gel, Pulsed-Field, Exotoxins genetics, Female, Hawaii epidemiology, Humans, Incidence, Infant, Infant, Newborn, Leukocidins genetics, Male, Microbial Sensitivity Tests, Middle Aged, Staphylococcal Infections microbiology, Staphylococcus aureus classification, Staphylococcus aureus genetics, Staphylococcus aureus pathogenicity, Community-Acquired Infections epidemiology, Methicillin Resistance genetics, Staphylococcal Infections epidemiology, Staphylococcus aureus drug effects
- Abstract
Objectives: We conducted a retrospective study to determine trends and characteristics of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) in Hawaii., Methods: We reviewed medical records of patients with MRSA infections during July 2001-June 2003 in four healthcare facilities. A case was defined as a patient with MRSA infection (colonization excluded), diagnosed in ambulatory settings or < or = 48 h after hospitalization, without previous MRSA or healthcare risk factors. Pulsed-field gel electrophoresis (PFGE) and typing of resistance and toxin genes was performed in 40 MRSA isolates., Results: CA-MRSA infections increased from 28 (23% of MRSA infections) to 65 (32%) per quarter over the 2-year period (P<0.05). Pacific islanders accounted for 51% of 389 case-patients, but only 24% of the Hawaii population. In the pediatric hospital, Pacific Islanders represented 76% of 90 case-patients versus 35% of the hospital population. Hospital admission, required for 40% (154/389), was associated with prior antimicrobial treatment (P<0.01). The staphylococcal cassette chromosome mec type IV was detected in 38/40 isolates; 31 isolates carried Panton-Valentine leukocidin genes and 22 belonged to the same staphylococcal lineage., Conclusions: In Hawaii, prevention strategies for CA-MRSA infections should focus on Pacific Islanders. CA-MRSA infections in Hawaii appear to be related to strains causing disease throughout the United States.
- Published
- 2007
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6. HIV-1 infection requires a functional integrase NLS.
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Bouyac-Bertoia M, Dvorin JD, Fouchier RA, Jenkins Y, Meyer BE, Wu LI, Emerman M, and Malim MH
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- Active Transport, Cell Nucleus drug effects, Amino Acid Sequence, Cell Nucleus virology, Cells, Cultured, DNA, Viral biosynthesis, HIV Integrase chemistry, HIV Integrase genetics, HeLa Cells, Humans, Leukocytes, Mononuclear virology, Mutagenesis, Site-Directed, Nuclear Localization Signals genetics, Nuclear Localization Signals physiology, Protein Structure, Tertiary, Sequence Alignment, Subcellular Fractions chemistry, T-Lymphocytes virology, HIV Infections enzymology, HIV Integrase metabolism, HIV-1, Nuclear Localization Signals pharmacology
- Abstract
HIV-1 is able to infect nondividing cells productively in part because the postentry viral nucleoprotein complexes are actively imported into the nucleus. In this manuscript, we identify a novel nuclear localization signal (NLS) in the viral integrase (IN) protein that is essential for virus replication in both dividing and nondividing cells. The IN NLS stimulates the efficient nuclear accumulation of viral DNA as well as virion-derived IN protein during the initial stages of infection but is dispensable for catalytic function. Because this NLS is required for infection irrespective of target cell proliferation, we suggest that interactions between uncoated viral nucleoprotein complexes and the host cell nuclear import machinery are critical for HIV-1 infection of all cells.
- Published
- 2001
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7. In vivo attenuation of simian immunodeficiency virus by disruption of a tyrosine-dependent sorting signal in the envelope glycoprotein cytoplasmic tail.
- Author
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Fultz PN, Vance PJ, Endres MJ, Tao B, Dvorin JD, Davis IC, Lifson JD, Montefiori DC, Marsh M, Malim MH, and Hoxie JA
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- Amino Acid Motifs, Amino Acid Sequence, Animals, Codon, Cytoplasm chemistry, Gene Products, env chemistry, Gene Products, env genetics, Gene Products, nef genetics, Macaca mulatta, Molecular Sequence Data, Mutation, Simian Immunodeficiency Virus chemistry, Structure-Activity Relationship, Tyrosine, Virus Replication, Gene Products, env physiology, Simian Immunodeficiency Virus pathogenicity
- Abstract
Attenuated simian immunodeficiency viruses (SIVs) have been described that produce low levels of plasma virion RNA and exhibit a reduced capacity to cause disease. These viruses are particularly useful in identifying viral determinants of pathogenesis. In the present study, we show that mutation of a highly conserved tyrosine (Tyr)-containing motif (Yxxphi) in the envelope glycoprotein (Env) cytoplasmic tail (amino acids YRPV at positions 721 to 724) can profoundly reduce the in vivo pathogenicity of SIVmac239. This domain constitutes both a potent endocytosis signal that reduces Env expression on infected cells and a sorting signal that directs Env expression to the basolateral surface of polarized cells. Rhesus macaques were inoculated with SIVmac239 control or SIVmac239 containing either a Tyr-721-to-Ile mutation (SIVmac239Y/I) or a deletion of Tyr-721 and the preceding glycine (DeltaGY). To assess the in vivo replication competence, all viruses contained a stop codon in nef that has been shown to revert during in vivo but not in vitro replication. All three control animals developed high viral loads and disease. One of two animals that received SIVmac239Y/I and two of three animals that received SIVmac239DeltaGY remained healthy for up to 140 weeks with low to undetectable plasma viral RNA levels and normal CD4(+) T-cell percentages. These animals exhibited ongoing viral replication as determined by detection of viral sequences and culturing of mutant viruses from peripheral blood mononuclear cells and persistent anti-SIV antibody titers. In one animal that received SIVmac239Y/I, the Ile reverted to a Tyr and was associated with a high plasma RNA level and disease, while one animal that received SIVmac239DeltaGY also developed a high viral load that was associated with novel and possibly compensatory mutations in the TM cytoplasmic domain. In all control and experimental animals, the nef stop codon reverted to an open reading frame within the first 2 months of inoculation, indicating that the mutant viruses had replicated well enough to repair this mutation. These findings indicate that the Yxxphi signal plays an important role in SIV pathogenesis. Moreover, because mutations in this motif may attenuate SIV through mechanisms that are distinct from those caused by mutations in nef, this Tyr-based sorting signal represents a novel target for future models of SIV and human immunodeficiency virus attenuation that could be useful in new vaccine strategies.
- Published
- 2001
- Full Text
- View/download PDF
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