The Trk family of neurotrophin tyrosine kinase receptors is emerging as an important player in carcinogenic progression in non-neuronal tissues. Here, we show that breast tumors present high levels ...of TrkA and phospho-TrkA compared to normal breast tissues. To further evaluate the precise functions of TrkA overexpression in breast cancer development, we have performed a series of biological tests using breast cancer cells that stably overexpress TrkA. We show that (1) TrkA overexpression promoted cell growth, migration and invasion in vitro; (2) overexpression of TrkA per se conferred constitutive activation of its tyrosine kinase activity; (3) signal pathways including PI3K-Akt and ERK/p38 MAP kinases were activated by TrkA overexpression and were required for the maintenance of a more aggressive cellular phenotype; and (4) TrkA overexpression enhanced tumor growth, angiogenesis and metastasis of xenografted breast cancer cells in immunodeficient mice. Moreover, recovered metastatic cells from the lungs exhibited enhanced anoikis resistance that was abolished by the pharmacological inhibitor K252a, suggesting that TrkA-promoted breast tumor metastasis could be mediated at least in part by enhancing anoikis resistance. Together, these results provide the first direct evidence that TrkA overexpression enhances the tumorigenic properties of breast cancer cells and point to TrkA as a potential target in breast cancer therapy.
Background and Purpose
Selective agonists of the sigma‐1 receptor (σ1 protein) are generally reported to protect against neuronal damage and modulate oligodendrocyte differentiation. Human and rodent ...lymphocytes possess saturable, high‐affinity binding sites for compounds binding to the σ1 protein and potential immunomodulatory properties have been described for σ1 protein ligands. Experimental autoimmune encephalomyelitis (EAE) is recognized as a valuable model of the inflammatory aspects of multiple sclerosis (MS). Here, we have assessed the role of a σ1 protein agonist, containing the tetrahydroisoquinoline‐hydantoin structure, in EAE.
Experimental Approach
EAE was induced in SJL/J female mice by active immunization with myelin proteolipid protein (PLP)139–151 peptide. The σ1 protein agonist was injected i.p. at the time of immunization (day 0). Disease severity was assessed clinically and by histopathological evaluation of the CNS. Phenotyping of B‐cell subsets and regulatory T‐cells were performed by flow cytometry in spleen and cervical lymph nodes.
Key Results
Prophylactic treatment of EAE mice with the σ1 protein agonist prevented mononuclear cell accumulation and demyelination in brain and spinal cord and increased T2 B‐cells and regulatory T‐cells, resulting in an overall reduction in the clinical progression of EAE.
Conclusions and Implications
This σ1 protein agonist, containing the tetrahydroisoquinoline‐hydantoin structure, decreased the magnitude of inflammation in EAE. This effect was associated with increased proportions of B‐cell subsets and regulatory T‐cells with potential immunoregulatory functions. Targeting of the σ1 protein might thus provide new therapeutic opportunities in MS.
Background and Purpose Selective agonists of the sigma-1 receptor ( sigma 1 protein) are generally reported to protect against neuronal damage and modulate oligodendrocyte differentiation. Human and ...rodent lymphocytes possess saturable, high-affinity binding sites for compounds binding to the sigma 1 protein and potential immunomodulatory properties have been described for sigma 1 protein ligands. Experimental autoimmune encephalomyelitis (EAE) is recognized as a valuable model of the inflammatory aspects of multiple sclerosis (MS). Here, we have assessed the role of a sigma 1 protein agonist, containing the tetrahydroisoquinoline-hydantoin structure, in EAE. Experimental Approach EAE was induced in SJL/J female mice by active immunization with myelin proteolipid protein (PLP) sub(139-151) peptide. The sigma 1 protein agonist was injected i.p. at the time of immunization (day 0). Disease severity was assessed clinically and by histopathological evaluation of the CNS. Phenotyping of B-cell subsets and regulatory T-cells were performed by flow cytometry in spleen and cervical lymph nodes. Key Results Prophylactic treatment of EAE mice with the sigma 1 protein agonist prevented mononuclear cell accumulation and demyelination in brain and spinal cord and increased T2 B-cells and regulatory T-cells, resulting in an overall reduction in the clinical progression of EAE. Conclusions and Implications This sigma 1 protein agonist, containing the tetrahydroisoquinoline-hydantoin structure, decreased the magnitude of inflammation in EAE. This effect was associated with increased proportions of B-cell subsets and regulatory T-cells with potential immunoregulatory functions. Targeting of the sigma 1 protein might thus provide new therapeutic opportunities in MS.
Background and Purpose Selective agonists of the sigma-1 receptor (σ1 protein) are generally reported to protect against neuronal damage and modulate oligodendrocyte differentiation. Human and rodent ...lymphocytes possess saturable, high-affinity binding sites for compounds binding to the σ1 protein and potential immunomodulatory properties have been described for σ1 protein ligands. Experimental autoimmune encephalomyelitis (EAE) is recognized as a valuable model of the inflammatory aspects of multiple sclerosis (MS). Here, we have assessed the role of a σ1 protein agonist, containing the tetrahydroisoquinoline-hydantoin structure, in EAE. Experimental Approach EAE was induced in SJL/J female mice by active immunization with myelin proteolipid protein (PLP)139-151 peptide. The σ1 protein agonist was injected i.p. at the time of immunization (day 0). Disease severity was assessed clinically and by histopathological evaluation of the CNS. Phenotyping of B-cell subsets and regulatory T-cells were performed by flow cytometry in spleen and cervical lymph nodes. Key Results Prophylactic treatment of EAE mice with the σ1 protein agonist prevented mononuclear cell accumulation and demyelination in brain and spinal cord and increased T2 B-cells and regulatory T-cells, resulting in an overall reduction in the clinical progression of EAE. Conclusions and Implications This σ1 protein agonist, containing the tetrahydroisoquinoline-hydantoin structure, decreased the magnitude of inflammation in EAE. This effect was associated with increased proportions of B-cell subsets and regulatory T-cells with potential immunoregulatory functions. Targeting of the σ1 protein might thus provide new therapeutic opportunities in MS.
HNF4α (hepatocyte nuclear factor 4α) belongs to a complex transcription factor network that is crucial for the function of hepatocytes and pancreatic β-cells. In these cells, it activates the ...expression of a very large number of genes, including genes involved in the transport and metabolism of glucose and lipids. Mutations in the HNF4α gene correlate with MODY1 (maturity-onset diabetes of the young 1), a form of type II diabetes characterized by an impaired glucose-induced insulin secretion. The MODY1 G115S (Gly115→Ser) HNF4α mutation is located in the DNA-binding domain of this nuclear receptor. We show here that the G115S mutation failed to affect HNF4α-mediated transcription on apolipoprotein promoters in HepG2 cells. Conversely, in pancreatic β-cell lines, this mutation resulted in strong impairments of HNF4α transcriptional activity on the promoters of LPK (liver pyruvate kinase) and HNF1α, with this transcription factor playing a key role in endocrine pancreas. We show as well that the G115S mutation creates a PKA (protein kinase A) phosphorylation site, and that PKA-mediated phosphorylation results in a decreased transcriptional activity of the mutant. Moreover, the G115E (Gly115→Glu) mutation mimicking phosphorylation reduced HNF4α DNA-binding and transcriptional activities. Our results may account for the 100% penetrance of diabetes in human carriers of this mutation. In addition, they suggest that introduction of a phosphorylation site in the DNA-binding domain may represent a new mechanism by which a MODY1 mutation leads to loss of HNF4α function.
Hepatocyte Nuclear Factor 4α (HNF4α, NR2A1) is central to hepatocyte and pancreatic β‐cell functions. Along with retinoid X receptor α (RXRα), HNF4α belongs to the nuclear receptor subfamily 2 (NR2), ...characterised by a conserved arginyl residue and a glutamate residue insert in helix 7 (H7) of the ligand binding domain (LBD). Crystallographic studies indicate that R348 and E352 residues in RXRα H7 are involved in charge‐driven interactions that improve dimerisation. Consistent with these findings, we showed that removing the charge of the corresponding residues in HNF4α H7, R258 and E262, impaired dimerisation in solution. Moreover, our results provide a new concept according to which helices of the HNF4α LBD dimerisation interface contribute differently to dimerisation required for DNA binding; unlike H9 and H10, H7 is not involved in DNA binding. Substitutions of E262 decreased the repression of HNF4α transcriptional activity by a dominant‐negative HNF4α mutant, highlighting the importance of this residue for dimerisation in the cell context. The E262 insert is crucial for HNF4α function since its deletion abolished HNF4α transcriptional activity and coactivator recruitment. The glutamate residue insert and the conserved arginyl residue in H7 most probably represent a signature of the NR2 subfamily of nuclear receptors.
Background: B cells appear to play an important role in the patho genesis of multiple sclerosis and they are also involved in regulatory mechanisms in a number of ways, such as cytokines secretion, ...production of natural autoantibodies and their ability to function as antigen-presenting cells to suppress encephalitogenic T cells. Objective: To study the implication of different B cells with potential regulatory behavior we analyzed T-independent B cell subsets distribution in spleen and cervical nodes. Methods: Transitional 2 (T2), marginal zone (MZ) and B1a B cells distribution were analyzed in murine experimental autoimmune encephalomyelitis (EAE) models developed in sensitive SJL/J and resistant C57BL/10.S mice for 60 days of protocol. The phenotypic analysis was carried out using a classic flow cytometry technique. Results: Our preliminary data revealed particular T2 and MZ B cell distributions during acute-recovery clinical course of disease in SJL/J-EAE mice. In the spleen, at disease onset, both T2 and MZ B cells show decreased proportions than those found at time of induction. T2 B cell levels rose when the recovery process started, while MZ B cells continued to decrease. Once total recovery was reached both T2 and MZ B cells recovered similar levels than in non-EAE mice. In cervical nodes, only MZ B cells show modification of distribution. The highest levels were observed at disease onset. No differences were found regarding B1a B cells in spleen and cervical nodes. In C57BL/B10.S-EAE mice MZ B cell proportions were sustained higher than those found in SJL/J-EAE mice, while T2 and B1a B cell were similar. Conclusions: These results indicate a possible role of T2 and MZ B cells in the regulation of initial resolution process in EAE. On the other hand, B1a B cells may also be involved in a regulatory process, probably acting in different sites than T2/MZ B cells.
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