Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 4 de 4
Filter
Add more filters










Database
Language
Publication year range
1.
Cell Rep ; 8(1): 242-55, 2014 Jul 10.
Article in English | MEDLINE | ID: mdl-25001282

ABSTRACT

Elevated hepatic synthesis of fatty acids and triglycerides, driven by hyperactivation of the SREBP-1c transcription factor, has been implicated as a causal feature of metabolic syndrome. SREBP-1c activation requires the proteolytic maturation of the endoplasmic-reticulum-bound precursor to the active, nuclear transcription factor, which is stimulated by feeding and insulin signaling. Here, we show that feeding and insulin stimulate the hepatic expression of PASK. We also demonstrate, using genetic and pharmacological approaches, that PASK is required for the proteolytic maturation of SREBP-1c in cultured cells and in the mouse and rat liver. Inhibition of PASK improves lipid and glucose metabolism in dietary animal models of obesity and dyslipidemia. Administration of a PASK inhibitor decreases hepatic expression of lipogenic SREBP-1c target genes, decreases serum triglycerides, and partially reverses insulin resistance. While the signaling network that controls SREBP-1c activation is complex, we propose that PASK is an important component with therapeutic potential.


Subject(s)
Dyslipidemias/metabolism , Lipogenesis , Obesity/metabolism , Protein Serine-Threonine Kinases/metabolism , Sterol Regulatory Element Binding Protein 1/metabolism , Animals , Cells, Cultured , HEK293 Cells , Hep G2 Cells , Hepatocytes/metabolism , Humans , Male , Mice , Protein Kinase Inhibitors/pharmacology , Protein Serine-Threonine Kinases/antagonists & inhibitors , Protein Serine-Threonine Kinases/genetics , Rats , Rats, Sprague-Dawley
2.
Mol Cancer Ther ; 10(12): 2267-75, 2011 Dec.
Article in English | MEDLINE | ID: mdl-21980130

ABSTRACT

Mps1 is a dual specificity protein kinase that is essential for the bipolar attachment of chromosomes to the mitotic spindle and for maintaining the spindle assembly checkpoint until all chromosomes are properly attached. Mps1 is expressed at high levels during mitosis and is abundantly expressed in cancer cells. Disruption of Mps1 function induces aneuploidy and cell death. We report the identification of MPI-0479605, a potent and selective ATP competitive inhibitor of Mps1. Cells treated with MPI-0479605 undergo aberrant mitosis, resulting in aneuploidy and formation of micronuclei. In cells with wild-type p53, this promotes the induction of a postmitotic checkpoint characterized by the ATM- and RAD3-related-dependent activation of the p53-p21 pathway. In both wild-type and p53 mutant cells lines, there is a growth arrest and inhibition of DNA synthesis. Subsequently, cells undergo mitotic catastrophe and/or an apoptotic response. In xenograft models, MPI-0479605 inhibits tumor growth, suggesting that drugs targeting Mps1 may have utility as novel cancer therapeutics.


Subject(s)
Adenine/analogs & derivatives , Antineoplastic Agents/pharmacology , Antineoplastic Agents/therapeutic use , Morpholines/pharmacology , Morpholines/therapeutic use , Neoplasms/drug therapy , Protein Serine-Threonine Kinases/antagonists & inhibitors , Adenine/isolation & purification , Adenine/pharmacology , Adenine/therapeutic use , Animals , Antineoplastic Agents/isolation & purification , Cell Line, Tumor , HCT116 Cells , Humans , Mice , Mice, Nude , Mitosis/drug effects , Mitosis/physiology , Models, Biological , Molecular Weight , Morpholines/isolation & purification , Neoplasms/pathology , Protein Kinase Inhibitors/isolation & purification , Protein Kinase Inhibitors/pharmacology , Protein Kinase Inhibitors/therapeutic use , Small Molecule Libraries/chemistry , Xenograft Model Antitumor Assays
3.
J Virol ; 81(13): 7099-110, 2007 Jul.
Article in English | MEDLINE | ID: mdl-17428871

ABSTRACT

Encapsidation of host restriction factor APOBEC3G (A3G) into vif-deficient human immunodeficiency virus type 1 (HIV-1) blocks virus replication at least partly by C-to-U deamination of viral minus-strand DNA, resulting in G-to-A hypermutation. A3G may also inhibit HIV-1 replication by reducing viral DNA synthesis and inducing viral DNA degradation. To gain further insight into the mechanisms of viral inhibition, we examined the metabolism of A3G-exposed viral DNA. We observed that an overall 35-fold decrease in viral infectivity was accompanied by a five- to sevenfold reduction in viral DNA synthesis. Wild-type A3G induced an additional fivefold decrease in the amount of viral DNA that was integrated into the host cell genome and similarly reduced the efficiency with which HIV-1 preintegration complexes (PICs) integrated into a target DNA in vitro. The A3G C-terminal catalytic domain was required for both of these antiviral activities. Southern blotting analysis of PICs showed that A3G reduced the efficiency and specificity of primer tRNA processing and removal, resulting in viral DNA ends that are inefficient substrates for integration and plus-strand DNA transfer. However, the decrease in plus-strand DNA transfer did not account for all of the observed decrease in viral DNA synthesis associated with A3G. These novel observations suggest that HIV-1 cDNA produced in the presence of A3G exhibits defects in primer tRNA processing, plus-strand DNA transfer, and integration.


Subject(s)
DNA, Complementary/metabolism , DNA, Viral/metabolism , HIV-1/physiology , Nucleoside Deaminases/metabolism , Repressor Proteins/metabolism , Virus Integration/physiology , Virus Replication/physiology , APOBEC-3G Deaminase , Catalytic Domain/genetics , Cell Line , Cytidine Deaminase , DNA, Complementary/genetics , Gene Products, vif/deficiency , Gene Products, vif/metabolism , Genome, Human , Humans , RNA Processing, Post-Transcriptional/physiology , RNA, Transfer/metabolism , vif Gene Products, Human Immunodeficiency Virus
4.
J Virol ; 80(7): 3634-43, 2006 Apr.
Article in English | MEDLINE | ID: mdl-16537631

ABSTRACT

Human T-cell leukemia virus type 1 (HTLV-1) Gag is targeted to the plasma membrane for particle assembly and release. How HTLV-1 Gag targeting occurs is not well understood. The PPPY and PTAP motifs were previously shown to be involved in HTLV-1 particle release with PTAP playing a more subtle role in virus budding. These L domains function through the interaction with host cellular proteins normally involved in multivesicular body (MVB) morphogenesis. The plasma membrane pathway rather than the MVB pathway was found to be the primary pathway for HTLV-1 particle release in HeLa cells. Intriguingly, disruption of the PTAP motif led to a defect in the targeting of Gag from the plasma membrane to CD63-positive MVBs. Particles or particle buds were observed to be associated with MVBs by electron microscopy, implying that Gag targeting to the MVB resulted in particle budding. Blocking clathrin-dependent endocytosis was found not to influence localization of the HTLV-1 Gag PTAP mutant, indicating that Gag did not reach the MVBs through clathrin-dependent endocytosis. Our observations imply that the interaction between Gag and TSG101 is not required for Gag targeting to the MVB. Overexpression of dynamitin p50 increased particle release, suggesting that there was an increase in the intracellular transport of MVBs to the cell periphery by the utilization of the dynein-dynactin motor complex. Intriguingly, virus particle release with this mutant was reduced by 20-fold compared to that of wild type in HeLa cells, which is in marked contrast to the less-than-twofold defect observed for particle production of the HTLV-1 Gag PTAP mutant from 293T cells. These results indicate that the role of the PTAP motif in L domain function is cell type dependent.


Subject(s)
Gene Products, gag/metabolism , Human T-lymphotropic virus 1/physiology , Virion/physiology , Amino Acid Motifs , Amino Acid Sequence , Antibodies, Monoclonal/metabolism , Antigens, CD/metabolism , Antigens, CD/ultrastructure , Autoantigens , Cell Membrane/metabolism , Cell Membrane/virology , Dynactin Complex , Fluorescent Antibody Technique, Indirect , Gene Products, gag/chemistry , Gene Products, gag/genetics , Gene Products, gag/ultrastructure , Genetic Markers , HeLa Cells , Human T-lymphotropic virus 1/chemistry , Human T-lymphotropic virus 1/genetics , Human T-lymphotropic virus 1/ultrastructure , Humans , Immunohistochemistry , Membrane Proteins/metabolism , Membrane Proteins/ultrastructure , Microscopy, Confocal , Microscopy, Electron , Microtubule-Associated Proteins/metabolism , Mutation , Plasmids , Protein Structure, Tertiary , Structure-Activity Relationship , Transfection , Transferrin/metabolism , Vesicular Transport Proteins , Virion/ultrastructure , Virus Assembly
SELECTION OF CITATIONS
SEARCH DETAIL
...