The JNK inhibitor, SP600125, potentiates the glial response and cell death induced by methamphetamine in the mouse striatum

This study investigates the effect of the selective Jun NH2-terminal kinase 1/2 (JNK1/2) inhibitor, (SP600125) on the striatal dopamine nerve terminal loss and on the increased interleukin-15 (IL-15) expression and glial response induced by methamphetamine (METH). Mice were given repeated low doses of METH (4Â mg/kg, i.p., three times separated by 3Â h) and killed 24Â h or 7 d after the last dose. SP600125 (30Â mg/kg, i.p) was administered 30Â min before the last METH injection. Results indicate that METH produced dopaminergic axonal neurotoxicity reflected as a marked decrease in the striatal density of tyrosine hydroxylase-immunoreactive (TH-ir) fibres and dopamine transporter-immunoreactivity (DAT-ir) 24Â h after dosing. These effects were not modified by SP600125. This compound also failed to prevent the long-term loss of dopamine levels and DAT observed 7 d following METH injection. Nevertheless, SP600125 potentiated METH-induced striatal cell loss reflected by an increase in Fluoro-Jade immunostaining, cleaved capase-3 immunoreactivity and the number of terminal deoxyncleotidyl transferase-mediated dUTP nick end labelling (TUNEL) positive cells. In line with a deleterious effect of JNK1/2 inhibition, SP600125 increased the astroglial and microglial response induced by METH and interfered with drug-induced IL-15 expression. Together these data indicate that, not only does SP600125 fail to protect against the dopaminergic damage induced by METH but also, in fact, it potentiates the glial response and the non-dopaminergic striatal cell loss caused by the drug. © 2013 CINP.Peer Reviewe

Glutaminase and MMP-9 downregulation in cortex and hippocampus of LPA1 receptor null mice correlate with altered dendritic spine plasticity

Lysophosphatidic acid (LPA) is an extracellular lipid mediator that regulates nervous system development and functions acting through G protein-coupled receptors (GPCRs). Here we explore the crosstalk between LPA1 receptor and glutamatergic transmission by examining expression of glutaminase (GA) isoforms in different brain areas isolated from wild-type (WT) and KOLPA1 mice. Silencing of LPA1 receptor induced a severe down-regulation of Gls-encoded long glutaminase protein variant (KGA) (glutaminase gene encoding the kidney-type isoforms, GLS) protein expression in several brain regions, particularly in brain cortex and hippocampus. Immunohistochemical assessment of protein levels for the second type of glutaminase (GA) isoform, glutaminase gene encoding the liver-type isoforms (GLS2), did not detect substantial differences with regard to WT animals. The regional mRNA levels of GLS were determined by real time RT-PCR and did not show significant variations, except for prefrontal and motor cortex values which clearly diminished in KO mice. Total GA activity was also significantly reduced in prefrontal and motor cortex, but remained essentially unchanged in the hippocampus and rest of brain regions examined, suggesting activation of genetic compensatory mechanisms and/or post-translational modifications to compensate for KGA protein deficit. Remarkably, Golgi staining of hippocampal regions showed an altered morphology of glutamatergic pyramidal cells dendritic spines towards a less mature filopodia-like phenotype, as compared with WT littermates. This structural change correlated with a strong decrease of active matrix-metalloproteinase (MMP) 9 in cerebral cortex and hippocampus of KOLPA1 mice. Taken together, these results demonstrate that LPA signaling through LPA1 influence expression of the main isoenzyme of glutamate biosynthesis with strong repercussions on dendritic spines maturation, which may partially explain the cognitive and learning defects previously reported for this colony of KOLPA1 mice

Chromatin regulation by Histone H4 acetylation at Lysine 16 during cell death and differentiation in the myeloid compartment

Histone H4 acetylation at Lysine 16 (H4K16ac) is a key epigenetic mark involved in gene regulation, DNA repair and chromatin remodeling, and though it is known to be essential for embryonic development, its role during adult life is still poorly understood. Here we show that this lysine is massively hyperacetylated in peripheral neutrophils. Genome-wide mapping of H4K16ac in terminally differentiated blood cells, along with functional experiments, supported a role for this histone post-translational modification in the regulation of cell differentiation and apoptosis in the hematopoietic system. Furthermore, in neutrophils, H4K16ac was enriched at specific DNA repeats. These DNA regions presented an accessible chromatin conformation and were associated with the cleavage sites that generate the 50 kb DNA fragments during the first stages of programmed cell death. Our results thus suggest that H4K16ac plays a dual role in myeloid cells as it not only regulates differentiation and apoptosis, but it also exhibits a non-canonical structural role in poising chromatin for cleavage at an early stage of neutrophil cell death

Cocaine potentiates MDMA-induced oxidative stress but not dopaminergic neurotoxicity in mice: implications for the pathogenesis of free radical-induced neurodegenerative disorders

RATIONALE: The drugs of abuse 3,4-methylenedioxymethamphetamine (MDMA; >ecstasy>) and cocaine both increase the generation of free radicals, and in the case of MDMA, this increase in oxidative stress is involved in the dopaminergic neurotoxicity produced by the drug in mice. Oxidative stress processes are also involved in the pathogenesis of several neurodegenerative diseases. OBJECTIVES: We aimed to determine the consequences of the combined administration of MDMA and cocaine on oxidative stress and dopaminergic neurotoxicity. METHODS: Mice received MDMA (20 mg/kg, i.p.; two doses separated by 3 h) followed by cocaine 1, 3, 6, or 24 h after the second MDMA dose. Mice were killed between 1 h and 7 days after cocaine injection. RESULTS: MDMA decreased dopamine transporter density and dopamine concentration 7 days later. Cocaine did not alter this neurotoxicity. MDMA produced an increase in the concentration of 2,3-dihydroxybenzoic acid in striatal microdialysis samples and an increase in lipid peroxidation in the striatum which were potentiated by cocaine. MDMA and cocaine given together also increased nitrate and 3-nitrotyrosine levels compared with either drug given alone. On the other hand, MDMA increased superoxide dismutase activity and decreased catalase activity, changes which were prevented by cocaine administration. In addition, cocaine administration produced an increase in glutathione peroxidase (GPx) activity in both saline-treated and MDMA-treated mice. CONCLUSIONS: Cocaine potentiates MDMA-induced oxidative stress but does not produce an increase in the neurotoxicity produced by MDMA, and this lack of potentiation may involve an increase in GPx activityPeer Reviewe

Mutations in RAS-BRAF-MAPK-ERK pathway define a specific subgroup of patients with adverse clinical features and provide new therapeutic options in chronic lymphocytic leukemia

Mutations in genes of the RAS-BRAF-MAPK-ERK pathwayhave not been fully explored in patients with chronic lym-phocytic leukemia. We, therefore, analyzed the clinical andbiological characteristics of chronic lymphocytic leukemia patientswith mutations in this pathway and investigated thein vitroresponseof primary cells to BRAF and ERK inhibitors. Putative damaging muta-tions were found in 25 of 452 patients (5.5%). Among these, BRAFwas mutated in nine patients (2.0%), genes upstream of BRAF(KITLG,KIT, PTPN11, GNB1, KRASand NRAS) were mutated in 12 patients(2.6%), and genes downstream of BRAF(MAPK2K1, MAPK2K2, andMAPK1) were mutated in five patients (1.1%). The most frequentmutations were missense, subclonal and mutually exclusive. Patientswith these mutations more frequently had increased lactate dehydro-genase levels, high expression of ZAP-70, CD49d, CD38, trisomy 12and unmutated immunoglobulin heavy-chain variable region genesand had a worse 5-year time to first treatment (hazard ratio 1.8,P=0.025). Gene expression analysis showed upregulation of genes ofthe MAPK pathway in the group carrying RAS-BRAF-MAPK-ERKpathway mutations. The BRAF inhibitors vemurafenib and dabrafenibwere not able to inhibit phosphorylation of ERK, the downstreameffector of the pathway, in primary cells. In contrast, ulixertinib, apan-ERK inhibitor, decreased phospho-ERK levels. In conclusion,although larger series of patients are needed to corroborate these find-ings, our results suggest that the RAS-BRAF-MAPK-ERK pathway isone of the core cellular processes affected by novel mutations inchronic lymphocytic leukemia, is associated with adverse clinical fea-tures and could be pharmacologically inhibited

Mutations in RAS-BRAF-MAPK-ERK pathway define a specific subgroup of patients with adverse clinical features and provide new therapeutic options in chronic lymphocytic leukemia

Mutations in genes of the RAS-BRAF-MAPK-ERK pathwayhave not been fully explored in patients with chronic lym-phocytic leukemia. We, therefore, analyzed the clinical andbiological characteristics of chronic lymphocytic leukemia patientswith mutations in this pathway and investigated thein vitroresponseof primary cells to BRAF and ERK inhibitors. Putative damaging muta-tions were found in 25 of 452 patients (5.5%). Among these, BRAFwas mutated in nine patients (2.0%), genes upstream of BRAF(KITLG,KIT, PTPN11, GNB1, KRASand NRAS) were mutated in 12 patients(2.6%), and genes downstream of BRAF(MAPK2K1, MAPK2K2, andMAPK1) were mutated in five patients (1.1%). The most frequentmutations were missense, subclonal and mutually exclusive. Patientswith these mutations more frequently had increased lactate dehydro-genase levels, high expression of ZAP-70, CD49d, CD38, trisomy 12and unmutated immunoglobulin heavy-chain variable region genesand had a worse 5-year time to first treatment (hazard ratio 1.8,P=0.025). Gene expression analysis showed upregulation of genes ofthe MAPK pathway in the group carrying RAS-BRAF-MAPK-ERKpathway mutations. The BRAF inhibitors vemurafenib and dabrafenibwere not able to inhibit phosphorylation of ERK, the downstreameffector of the pathway, in primary cells. In contrast, ulixertinib, apan-ERK inhibitor, decreased phospho-ERK levels. In conclusion,although larger series of patients are needed to corroborate these find-ings, our results suggest that the RAS-BRAF-MAPK-ERK pathway isone of the core cellular processes affected by novel mutations inchronic lymphocytic leukemia, is associated with adverse clinical fea-tures and could be pharmacologically inhibited

Chromatin regulation by Histone H4 acetylation at Lysine 16 during cell death and differentiation in the myeloid compartment

Histone H4 acetylation at Lysine 16 (H4K16ac) is a key epigenetic mark involved in gene regulation, DNA repair and chromatin remodeling, and though it is known to be essential for embryonic development, its role during adult life is still poorly understood. Here we show that this lysine is massively hyperacetylated in peripheral neutrophils. Genome-wide mapping of H4K16ac in terminally differentiated blood cells, along with functional experiments, supported a role for this histone post-translational modification in the regulation of cell differentiation and apoptosis in the hematopoietic system. Furthermore, in neutrophils, H4K16ac was enriched at specific DNA repeats. These DNA regions presented an accessible chromatin conformation and were associated with the cleavage sites that generate the 50 kb DNA fragments during the first stages of programmed cell death. Our results thus suggest that H4K16ac plays a dual role in myeloid cells as it not only regulates differentiation and apoptosis, but it also exhibits a non-canonical structural role in poising chromatin for cleavage at an early stage of neutrophil cell death

Chromatin regulation by Histone H4 acetylation at Lysine 16 during cell death and differentiation in the myeloid compartment

Altres ajuts: Fundación Científica de la AECC (to R.G.U.); Fundación Ramón Areces (to M.F.F); FICYT (to E.G.T., M.G.G., A.C.); Asturias Regional Government [GRUPIN14-052 to M.F.F.]; Gobierno del Principado de Asturias, PCTI-Plan de Ciencia, Tecnología e Innovación co-funding Fondos FEDER (grant number IDI/2018/146 to M.F.F. and IDI/2018/144 to C.L.); Asociación Española Contra el Cáncer [AECC-CI-2015]; P.M. acknowledges financial support from The Obra Social La Caixa-Fundaciò Josep Carreras. P.M. an investigator from the Spanish Cell Therapy cooperative network (TERCEL). The IUOPA is supported by the Obra Social Liberbank-Cajastur, Spain.Histone H4 acetylation at Lysine 16 (H4K16ac) is a key epigenetic mark involved in gene regulation, DNA repair and chromatin remodeling, and though it is known to be essential for embryonic development, its role during adult life is still poorly understood. Here we show that this lysine is massively hyperacetylated in peripheral neutrophils. Genome-wide mapping of H4K16ac in terminally differentiated blood cells, along with functional experiments, supported a role for this histone post-translational modification in the regulation of cell differentiation and apoptosis in the hematopoietic system. Furthermore, in neutrophils, H4K16ac was enriched at specific DNA repeats. These DNA regions presented an accessible chromatin conformation and were associated with the cleavage sites that generate the 50 kb DNA fragments during the first stages of programmed cell death. Our results thus suggest that H4K16ac plays a dual role in myeloid cells as it not only regulates differentiation and apoptosis, but it also exhibits a non-canonical structural role in poising chromatin for cleavage at an early stage of neutrophil cell death