1,721,006 research outputs found
BDNF splice variants from the second promoter cluster support cell survival of differentiated neuroblastoma upon cytotoxic stress
No full textThe neurotrophin brain-derived neurotrophic factor (BDNF) is a key survival factor for neural cells. In particular, in neuroblastoma tumour cells, expression of the BDNF/TrkB autocrine signalling system promotes a more malignant phenotype and resistance to chemotherapy. The human BDNF gene contains two clusters of upstream exons encoding the 5 UTR (exon 1 to exon 3 and exon 4 to exon 9a), these are alternatively spliced to a common exon 9, which contains the coding region and the 3 UTR. At least 34 different BDNF mRNA transcripts can be generated, although their physiological role is still unknown. The purpose of this study is to determine which BDNF transcript is involved in cell survival of the human neuroblastoma cell lines SH-SY-5Y (single-copy MYCN) and SK-N-BE (amplified MYCN). Expression of human BDNF mRNAs encoding all possible isoforms was characterised in the two neuroblastoma cell lines. We then investigated whether selective silencing of the different BDNF mRNAs using spec
Evolutionary conserved mechanisms of RNA trafficking in neurons and the regulation of spine morphology.
No full text
METHOD FOR THE SELECTION OFCOMPOUNDS USEFUL FOR THETREATMENT OF NEUROPSYCHIATRICAND NEURODEGENERATIVEDISEASES
No full textBlockade of BDNF signaling turns chemically-induced long-term potentiation into long-term depression
No full textLong-term potentiation (LTP) is accompanied by increased spine density and dimensions triggered by signaling cascades involving activation of the neurotrophin brain-derived neurotrophic factor (BDNF) and cytoskeleton remodelling. Chemically-induced long-term potentiation (c-LTP) is a widely used cellular model of plasticity whose effects on spines have been poorly investigated. We induced c-LTP by bath-application of the N-methyl-D-aspartate receptor (NMDAR) co-agonist glycine or by the K+ channel blocker tetraethylammonium (TEA) chloride in cultured hippocampal neurons and compared the changes in dendritic spines induced by the two models of c-LTP and determined if they depend on BDNF/TrkB signaling. We found that both TEA and glycine induced a significant increase in stubby spine density in primary and secondary apical dendrites, whereas a specific increase in mushroom spine density was observed upon TEA application only in primary dendrites. Both TEA and glycine increased BDNF levels and the blockade of tropomyosin-receptor-kinase receptors (TrkRs) by the non selective tyrosine kinase inhibitor K-252a or the selective allosteric TrkB receptor (TrkBR) inhibitor ANA-12, abolished the c-LTP-induced increase in spine density. Surprisingly, a blockade of TrkBRs did not change basal spontaneous glutamatergic transmission but completely changed the synaptic plasticity induced by c-LTP, provoking a shift from a long-term increase to a long-term depression (LTD) in miniature excitatory postsynaptic current (mEPSC) frequency. In conclusion, these results suggest that BDNF/TrkB signaling is necessary for c-LTP-induced plasticity in hippocampal neurons and its blockade leads to a switch of c-LTP into chemical-LTD (c-LTD)
BDNF mRNA splice variants display activity-dependent targeting to distinct hippocampal laminae
No full textSpatial segregation of BDNF transcripts enables BDNF to differentially shape distinct dendritic compartments.
No full textBDNF is produced from many transcripts that display distinct
subcellular localization, suggesting that spatially restricted effects
occur as a function of genetic and physiological regulation. Different
BDNF 5′ splice variants give a restricted localization in the
cell body or the proximal and distal compartments of dendrites;
however, the functional consequences are not known. Silencing
individual endogenous transcripts or overexpressing BDNF-GFP
transcripts in cultured neurons demonstrated that whereas some
transcripts (1 and 4) selectively affected proximal dendrites, others
(2C and 6) affected distal dendrites. Moreover, segregation of
BDNF transcripts resulted in a highly selective activation of the
BDNF TrkB receptor. These studies indicate that spatial segregation
of BDNF transcripts enables BDNF to differentially shape distinct
dendritic compartments
Developmental and maintenance defects in Rett syndrome neurons identified by a new mouse staging system in vitro.
No full textRett Syndrome (RTT) is a neurodevelopmental disorder associated with intellectual disability, mainly caused by loss-of-function mutations in the MECP2 gene. RTT brains display decreased neuronal size and dendritic arborization possibly caused by either a developmental failure or a deficit in the maintenance of dendritic arbor structure. To distinguish between these two hypotheses, the development of Mecp2-knockout mouse hippocampal neurons was analyzed in vitro. Since a staging system for the in vitro development of mouse neurons was lacking, mouse and rat hippocampal neurons development was compared between 1–15 days in vitro (DIV) leading to a 6-stage model for both species. Mecp2-knockout hippocampal neurons displayed reduced growth of dendritic branches from stage 4 (DIV4) onwards. At stages 5–6 (DIV9-15), synapse number was lowered in Mecp2-knockout neurons, suggesting increased synapse elimination. These results point to both a developmental and a maintenance setback affecting the final shape and function of neurons in RTT
Aptamer targeting of the elongation factor 1A impairs hepatocarcinoma cells viability and potentiates bortezomib and idarubicin effects
Full text linkThe high morbidity and mortality of hepatocellular carcinoma (HCC) is mostly due to the limited efficacy
of the available therapeutic approaches. Here we explore the anti-HCC potential of an aptamer targeting
the elongation factor 1A (eEF1A), a protein implicated in the promotion of HCC. As delivery methods, we
have compared the effectiveness of cationic liposome and cholesterol-mediated approaches.
A75 nucleotide long aptamer containing GT repetition (GT75) was tested in three HCC cell lines, HepG2,
HuH7 and JHH6. When delivered by liposomes, GT75 was able to effectively reducing HCC cells viability
in a dose and time dependent fashion. Particular sensitive were JHH6 where increased apoptosis with no
effects on cell cycle were observed. GT75 effect was likely due to the interference with eEF1A activity as
neither the mRNA nor the protein levels were significantly affected. Notably, cholesterol-mediated
delivery of GT75 abrogated its efficacy due to cellular mis-localization as proven by
fluorescence and
confocal microscopic analysis. Finally, liposome-mediated delivery of GT75 improved the therapeutic
index of the anticancer drugs bortezomib and idarubicin.
In conclusion, liposome but not cholesterol-mediated delivery of GT75 resulted in an effective delivery
of GT75, causing the impairment of the vitality of a panel of HCC derived cells
Pharmacological profile of brain-derived neurotrophic factor (BDNF) splice variant translation using a novel drug screening assay b
No full textThe neurotrophin brain-derived neurotrophic factor (BDNF) is a key regulator of neuronal development and plasticity. BDNF is a major pharmaceutical target in neurodevelopmental and psychiatric disorders. However, pharmacological modulation of this neurotrophin is challenging because BDNF is generated by multiple, alternatively spliced transcripts with different 5'- and 3'UTRs. Each BDNF mRNA variant is transcribed independently, but translation regulation is unknown. To evaluate the translatability of BDNF transcripts, we developed an in vitro luciferase assay in human neuroblastoma cells. In unstimulated cells, each BDNF 5'- and 3'UTR determined a different basal translation level of the luciferase reporter gene. However, constructs with either a 5'UTR or a 3'UTR alone showed poor translation modulation by BDNF, KCl, dihydroxyphenylglycine, AMPA, NMDA, dopamine, acetylcholine, norepinephrine, or serotonin. Constructs consisting of the luciferase reporter gene flanked by the 5'UTR of one of the most abundant BDNF transcripts in the brain (exons 1, 2c, 4, and 6) and the long 3'UTR responded selectively to stimulation with the different receptor agonists, and only transcripts 2c and 6 were increased by the antidepressants desipramine and mirtazapine. We propose that BDNF mRNA variants represent "a quantitative code" for regulated expression of the protein. Thus, to discriminate the efficacy of drugs in stimulating BDNF synthesis, it is appropriate to use variant-specific in vitro screening tests
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