ABSTRACT
We have previously demonstrated that thyromimetics stimulate oligodendrocyte precursor cell differentiation and promote remyelination in murine demyelination models. We investigated whether a thyroid receptor-beta selective thyromimetic, sobetirome (Sob), and its CNS-targeted prodrug, Sob-AM2, could prevent myelin and axonal degeneration in experimental autoimmune encephalomyelitis (EAE). Compared to controls, EAE mice receiving triiodothyronine (T3, 0.4 mg/kg), Sob (5 mg/kg) or Sob-AM2 (5 mg/kg) had reduced clinical disease and, within the spinal cord, less tissue damage, more normally myelinated axons, fewer degenerating axons and more oligodendrocytes. T3 and Sob also protected cultured oligodendrocytes against cell death. Thyromimetics thus might protect against oligodendrocyte death, demyelination and axonal degeneration as well as stimulate remyelination in multiple sclerosis.
Subject(s)
Acetates/pharmacology , Encephalomyelitis, Autoimmune, Experimental/pathology , Myelin Sheath/drug effects , Oligodendroglia/drug effects , Phenols/pharmacology , Triiodothyronine/pharmacology , Animals , Demyelinating Diseases/pathology , Female , Mice , Mice, Inbred C57BL , Nerve Degeneration/pathology , Prodrugs/pharmacologyABSTRACT
The anti-oxidant lipoic acid (LA) potently suppresses clinical and pathologic disease in the animal model of multiple sclerosis, experimental autoimmune encephalomyelitis, by inhibiting the migration of pathogenic T cells to the spinal cord. The mechanism by which this occurs is largely unknown. In this report we demonstrate that LA induces increases in cyclic AMP, a known immunosuppressant, in human T cells. The increase in cAMP is associated with increased adenylyl cyclase activity and is partially blocked by prostanoid receptor antagonists. We present evidence that LA also stimulates cAMP production in natural killer (NK) cells. This novel mechanism of action is highly relevant to the immunomodulatory effects of LA and provides further support for the study of LA as a therapeutic agent for multiple sclerosis and other autoimmune diseases.
Subject(s)
Cyclic AMP/biosynthesis , Killer Cells, Natural/metabolism , T-Lymphocytes/metabolism , Thioctic Acid/administration & dosage , Cells, Cultured , Dose-Response Relationship, Drug , Humans , Immunologic Factors/administration & dosage , Killer Cells, Natural/drug effects , T-Lymphocytes/drug effectsABSTRACT
The simian retrovirus (SRV) genome contains a constitutive transport element (CTE) within its 3' intergenic region (IR) that mediates the nuclear export of unspliced SRV RNA. The serogroup 2 SRV CTE is predicted to form a stable stem-loop structure containing two major internal loops exhibiting 180 degrees inverse symmetry, with loop face sequences A, A', B, and B' and additional minor internal and terminal loops. To begin the identification of potential CTE-interacting proteins and to assess structural requirements for protein interaction, we conducted RNA mobility shift assays using IR fragments that obliterated this region's known stable stem-loop structure. Using immunoblotting assays, we have determined that RNA helicase A, implicated in the nuclear export of unspliced SRV genomic RNA, does not appear to interact directly with either the complete serogroup 2 SRV 3' IR or the subregion RNAs and that formation of RNA-protein complexes is conferred by interaction with other novel proteins. UV crosslinking of RNA-protein complexes, coupled with RNase T1/A digestion, indicates that a novel protein of 120 kDa molecular weight interacts with the complete CTE or with individual subregion RNAs. Transfection analyses indicate that SRV recombinants containing A, A', B, or B' sequences forming the faces for two open loops undergo RNA export; only the complete sense CTE recombinant or a second recombinant containing two subregions in sense orientation that reconstitute the 3' two-thirds of the 3' IR, and contain only A' and B that form the faces for two terminal loops, are capable of SRV RNA export. These experiments indicate that secondary structural determinants of the 3' IR and multiple protein interactions may be important factors in the nuclear export of unspliced SRV RNA.
Subject(s)
RNA Helicases/metabolism , RNA, Viral/genetics , Retroviruses, Simian/chemistry , Retroviruses, Simian/genetics , Animals , Base Sequence , Cell Line , Cell Nucleus/virology , Chlorocebus aethiops , Cytoplasm/virology , DNA, Ribosomal/chemistry , DNA, Ribosomal/genetics , Genome, Viral , Humans , Introns , Models, Molecular , Molecular Sequence Data , Mutagenesis, Site-Directed , Nucleic Acid Conformation , Tumor Cells, CulturedABSTRACT
Simian retroviruses (SRVs), the etiological agent of a spontaneous Simian acquired immunodeficiency syndrome, endemically infects large percentages of Asian macaques housed in biomedical research colonies and severely compromises the effective use of these species as a viable research animal. We recently described the molecular cloning of a serogroup 2 SRV, D2/RHE/OR, which causes mild immunosuppression in rhesus macaques. A restriction site variant, D2/RHE/OR/V1, has also been recovered from severely ill animals endemically infected with D2/RHE/OR. We now report the complete nucleotide sequences of D2/RHE/OR and D2/RHE/OR/V1. Both infectious molecular clones retain the genetic structure typical of type D SRVs (5' LTR-gag-prt-pol-env-3'LTR) and encode identically sized 8105-bp proviruses. D2/RHE/OR and D2/RHE/OR/V1 are 99.3% similar at the amino acid level, exhibiting only 17 residue differences, of which 10 are located in the envelope glycoproteins. The molecular clones and reciprocal chimeric viruses were used to assess the contribution of different genetic domains to virus infectivity in a T cell infection assay. These experiments indicate that D2/RHE/OR has a reduced ability to infect specific T cell lines, especially Hut-78 and MT-4 cells, and that the envelope gene is not the sole determinant of in vitro tropism.
Subject(s)
Cloning, Molecular , Genes, Viral , Polymorphism, Genetic , Retroviruses, Simian/growth & development , Retroviruses, Simian/genetics , Simian Acquired Immunodeficiency Syndrome/virology , Amino Acid Sequence , Animals , Cells, Cultured , DNA, Recombinant , Endopeptidases/genetics , Genes, env/genetics , Genes, gag/genetics , Genes, pol/genetics , Genetic Variation , Macaca , Molecular Sequence Data , Monkey Diseases/virology , Proviruses/genetics , Retroviruses, Simian/classification , Sequence Analysis, DNA , T-Lymphocytes/virology , Terminal Repeat Sequences/geneticsABSTRACT
We describe the molecular cloning of a serogroup 2 simian retrovirus (SRV; D2/RHE/OR) and present the sequence of its envelope (env) glycoprotein gene and 3' long terminal repeat region. This report documents the first infectious molecular clone of a serogroup 2 SRV and provides env sequence verification of genetic diversity among serogroup 2 SRV isolates.