Biomedical subjects

Fernando Dangond

Publications and source records attributed to Fernando Dangond.

7 recordsLinked to original sources

PubMed2006

Histone deacetylase 3 represses HTLV-1 tax transcription.

We examined the epigenetic mechanisms involved in human T-cell lymphotropic virus type 1 (HTLV-1) Tax expression. Blockade of histone deacetylation with trichostatin A (TSA) resulted in Tax upregulation. Using a chromatin immunoprecipitation (ChIP) assay, we verified local histone hyperacetylation at the HTLV-1 LTR in response to TSA. In agreement, HDAC3 transfection led to reductions in both Tax expression and histone acetylation. HDAC3 mutations and deletions spanning the catalytic site had variable ability to repress Tax, but HDAC activity was not essential for repression. Immunoprecipitation studies revealed that Tax co-exists in a complex containing both histone deacetylase 1 (HDAC1) and 3 (HDAC3). Our results suggest that HDACs may actively participate in the repression of HTLV-1 Tax transcription.

Acetylation↗

PubMed2005

Functional characterization of JMJD2A, a histone deacetylase- and retinoblastoma-binding protein.

To effectively direct targeted repression, the class I histone deacetylases (HDACs) associate with many important regulatory proteins. In this paper we describe the molecular characterization of a member of the Jumonji domain 2 (JMJD2) family of proteins, and demonstrate its binding to both class I HDACs and the retinoblastoma protein (pRb). JMJD2 proteins are characterized by the presence of two leukemia-associated protein/plant homeodomain (LAP/PHD) zinc fingers, one JmjN, one JmjC (containing an internal retinoblastoma-binding protein 2 (RBBP2)-like sequence), and two Tudor domains. The first member of this group, JMJD2A, is widely expressed in human tissues and cell lines, and high endogenous expression of JMJD2A mRNA was found in several cell types, including human T-cell lymphotropic virus 1 (HTLV-1)-infected cell lines. JMJD2A and JMJD2B exhibit cell type-specific responses to the HDAC inhibitor trichostatin A. We show that the JMJD2A protein associates in vivo with pRb and class I HDACs, and mediates repression of E2F-regulated promoters. In HTLV-1 virus-infected cells, we find that JMJD2A binds to the viral Tax protein. Antibodies to JMJD2A recognize the native protein but also a half-sized protein fragment, the latter up-regulated in THP-1 cells during the G(2)/M phase of the cell cycle. The ability of JMJD2A to associate with pRb and HDACs and potentiate pRb-mediated repression of E2F-regulated promoters implies an important role for this protein in cell proliferation and oncogenesis.

Amino Acid Sequence↗

PubMed2005

Transcriptional therapy with the histone deacetylase inhibitor trichostatin A ameliorates experimental autoimmune encephalomyelitis.

We demonstrate that the histone deacetylase (HDAC) inhibitor drug trichostatin A (TSA) reduces spinal cord inflammation, demyelination, neuronal and axonal loss and ameliorates disability in the relapsing phase of experimental autoimmune encephalomyelitis (EAE), a model of multiple sclerosis (MS). TSA up-regulates antioxidant, anti-excitotoxicity and pro-neuronal growth and differentiation mRNAs. TSA also inhibits caspase activation and down-regulates gene targets of the pro-apoptotic E2F transcription factor pathway. In splenocytes, TSA reduces chemotactic, pro-Th1 and pro-proliferative mRNAs. A transcriptional imbalance in MS may contribute to immune dysregulation and neurodegeneration, and we identify HDAC inhibition as a transcriptional intervention to ameliorate this imbalance.

Animals↗

PubMed2005

Sodium phenylbutyrate prolongs survival and regulates expression of anti-apoptotic genes in transgenic amyotrophic lateral sclerosis mice.

Multiple molecular defects trigger cell death in amyotrophic lateral sclerosis (ALS). Among these, altered transcriptional activity may perturb many cellular functions, leading to a cascade of secondary pathological effects. We showed that pharmacological treatment, using the histone deacetylase inhibitor sodium phenylbutyrate, significantly extended survival and improved both the clinical and neuropathological phenotypes in G93A transgenic ALS mice. Phenylbutyrate administration ameliorated histone hypoacetylation observed in G93A mice and induced expression of nuclear factor-kappaB (NF-kappaB) p50, the phosphorylated inhibitory subunit of NF-kappaB (pIkappaB) and beta cell lymphoma 2 (bcl-2), but reduced cytochrome c and caspase expression. Curcumin, an NF-kappaB inhibitor, and mutation of the NF-kappaB responsive element in the bcl-2 promoter, blocked butyrate-induced bcl-2 promoter activity. We provide evidence that the pharmacological induction of NF-kappaB-dependent transcription and bcl-2 gene expression is neuroprotective in ALS mice by inhibiting programmed cell death. Phenylbutyrate acts to phosphorylate IkappaB, translocating NF-kappaB p50 to the nucleus, or to directly acetylate NF-kappaB p50. NF-kappaB p50 transactivates bcl-2 gene expression. Up-regulated bcl-2 blocks cytochrome c release and subsequent caspase activation, slowing motor neuron death. These transcriptional and post-translational pathways ultimately promote motor neuron survival and ameliorate disease progression in ALS mice. Phenylbutyrate may therefore provide a novel therapeutic approach for the treatment of patients with ALS.

Acetylation↗

PubMed2004

Molecular signature of late-stage human ALS revealed by expression profiling of postmortem spinal cord gray matter.

Little is known about global gene expression patterns in the human neurodegenerative disease amyotrophic lateral sclerosis (ALS). To address this, we used high-density oligonucleotide microarray technology to compare expression levels of approximately 6,800 genes in postmortem spinal cord gray matter obtained from individuals with ALS as well as normal individuals. Using Fisher discriminant analysis (FDA) and leave-one-out cross-validation (LOOCV), we discerned an ALS-specific signature. Moreover, it was possible to distinguish familial ALS (FALS) from sporadic ALS (SALS) gene expression profiles. Characterization of the specific genes significantly altered in ALS uncovered a pro-inflammatory terminal state. Moreover, we found alterations in genes involved in mitochondrial function, oxidative stress, excitotoxicity, apoptosis, cytoskeletal architecture, RNA transcription and translation, proteasomal function, and growth and signaling. It is apparent from this study that DNA microarray analysis and appropriate bioinformatics can reveal distinct phenotypic changes that underlie the terminal stages of neurodegeneration in ALS.

Amyotrophic Lateral Sclerosis↗

PubMed2004

Microarray detection of E2F pathway activation and other targets in multiple sclerosis peripheral blood mononuclear cells.

We performed microarray analysis of peripheral blood mononuclear cells (PBMCs) from multiple sclerosis (MS) patients and detected a profile of immune cell activation, autoantigen upregulation, and enhanced E2F pathway transcription. Accordingly, E2f1-deficient mice manifested only mild disability upon induction of experimental autoimmune encephalomyelitis (EAE). Furthermore, PBMCs from Avonex-treated patients had lower expression of E2F targets. The profile was enriched in genes known to harbor MS-associated polymorphisms, or localized to MS susceptibility chromosomal regions. Our study shows that PBMC microarrays reflect MS pathobiology that can be validated in the EAE model.

Adolescent↗

PubMed2004

Neural stem/progenitor cells express costimulatory molecules that are differentially regulated by inflammatory and apoptotic stimuli.

Increased expression of the costimulatory molecule CD80 (B7-1) was noted in the subventricular zone of the brain during the course of experimental autoimmune encephalomyelitis (EAE). This area of the brain is a neural stem cell (NSC) niche in the adult. We show that isolated NSCs from adult brain express CD80 and CD86 (B7-2) and this expression is increased after exposure to IFN-gamma or TNF-alpha, the prototypical Th1 cytokines expressed during EAE. CD80 and CD86 expressed by NSCs are functional and can costimulate allogeneic cells in a mixed lymphocyte reaction. Furthermore, cross-linking of CD80 on the surface of NSCs results in apoptosis of NSCs. In vitro, we show that T cells can interact with NSCs and form conjugates with redistribution of CD3 on the surface of T cells to the area of contact. These data raise the possibility that during CNS inflammatory diseases such as EAE, NSCs may express immune molecules and interact with the inflammatory environment potentially resulting in injury to the NSCs, which may have implications for repair mechanisms in the central nervous system.

Animals↗