αCaMKII autophosphorylation levels differ depending on subcellular localization

Davies, Kurtis D.; Alvestad, Rachel M.; Coultrap, Steven J.; Browning, Michael

doi:10.1016/j.brainres.2007.05.008

Cited by 27 publications

(38 citation statements)

References 69 publications

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“…Mer knockdown in 697 cells (see Figure 2B) was quantified by densitometric analysis of semiquantitative Western blots using AlphaEase software (Alpha Innotech) as previously described. 25 …”

Section: Western Blottingmentioning

confidence: 99%

Mer receptor tyrosine kinase is a novel therapeutic target in pediatric B-cell acute lymphoblastic leukemia

Linger¹,

DeRyckere²,

Brandão³

et al. 2009

Blood

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Acute lymphoblastic leukemia (ALL) is currently treated with an intense regimen of chemotherapy yielding cure rates near 80%. However, additional changes using available drugs are unlikely to provide significant improvement in survival. New therapies are warranted given the risk of severe therapy-associated toxicities including infertility, organ damage, and secondary malignancy. Here, we report ectopic expression of the receptor tyrosine kinase Mer in pediatric B-cell ALL. Inhibition of Mer prevented Erk 1/2 activation, increased the sensitivity of B-ALL cells to cytotoxic agents in vitro by promoting apoptosis, and delayed disease onset in a mouse model of leukemia. In addition, we discovered cross-talk between the Mer and mammalian target of rapamycin (mTOR) signaling pathways. Our results identify Mer as a novel therapeutic target in ALL and suggest that inhibitors of Mer will interact synergistically with currently used therapies. This strategy may allow for dose reduction resulting in decreased toxicity and increased survival rates. Mer is aberrantly expressed in numerous other malignancies suggesting that this approach may have broad applications.

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Section: Western Blottingmentioning

confidence: 99%

Mer receptor tyrosine kinase is a novel therapeutic target in pediatric B-cell acute lymphoblastic leukemia

Linger¹,

DeRyckere²,

Brandão³

et al. 2009

Blood

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“…Immunodetection was accomplished using a chemiluminescence substrate kit (SuperSignal West Femto Maximum Sensitivity Substrate, Thermo Scientific) and Alpha Innotech (Alpha Innotech, San Leandro, CA) imaging system. Total protein concentration were determined relative to a 5 point standard curve to ensure protein concentrations were in the linear range of detection and for quantification of immunoreactivity/μg protein (Davies et al, 2007), and are normalized to age matched controls. Total protein expression and phosphorylated protein expression were assessed from the same blots by stripping (Restore PLUS Western Stripping Buffer, ThermoScientific) and re-probing.…”

Section: Methodsmentioning

confidence: 99%

Enhanced long term potentiation and decreased AMPA receptor desensitization in the acute period following a single kainate induced early life seizure

O’Leary

Bernard

Castano

et al. 2016

Neurobiology of Disease

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Neonatal seizures are associated with long term disabilities including epilepsy and cognitive deficits. Using a neonatal seizure rat model that does not develop epilepsy, but develops a phenotype consistent with other models of intellectual disability (ID) and autism spectrum disorders (ASD), we sought to isolate the acute effects of a single episode of early life seizure on hippocampal CA1 synaptic development and plasticity. We have previously shown chronic changes in glutamatergic synapses, loss of long term potentiation (LTP) and enhanced long term depression (LTD), in the adult male rat ~50 days following kainic acid (KA) induced early life seizure (KA-ELS) in post-natal (P) 7 day old male Sprague-Dawley rats. In the present work, we examined the electrophysiological properties and expression levels of glutamate receptors in the acute period, 2 and 7 days, post KA-ELS. Our results show for the first time enhanced LTP 7 days after KA-ELS, but no change 2 days post KA-ELS. Additionally, we report that ionotropic α-amino-3-hydroxy-5-methyl-isoxazole-propionic acid type glutamate receptor (AMPAR) desensitization is decreased in the same time frame, with no changes in AMPAR expression, phosphorylation, or membrane insertion. Inappropriate enhancement of the synaptic connections in the acute period after the seizure could alter the normal patterning of synaptic development in the hippocampus during this critical period and contribute to learning deficits. Thus, this study demonstrates a novel mechanism by which KA-ELS alters early network properties that potentially lead to adverse outcomes.

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“…Therefore, we also analyzed AMPAR expression in the synaptic and extrasynaptic pools. A classical subcellular fractionation approach (33)(34)(35) was modified to obtain fractions from the minislices enriched for synaptic and extrasynaptic membranes (36). This method capitalizes on the fact that PSDs and synaptic junctions are insoluble in Triton X-100 (44,45).…”

Section: Resultsmentioning

confidence: 99%

“…The final pellets were sonicated and boiled in 1% SDS, 1 mM EDTA, and 10 mM Tris (pH 8) for 5 min and kept at Ϫ80°C. We have previously characterized these fractionation procedures (36,37).…”

Section: Methodsmentioning

confidence: 99%

“…Following harvesting, the slices were immediately homogenized in a glass grinding vessel by a Teflon pestle rotating at 1000 rpm. Subsequently, a subcellular fractionation protocol was employed (11,(33)(34)(35)(36). The homogenate was spun at 1000 ϫ g for 10 min, and the pellet (P1), which contains nuclei and incompletely homogenized material, was discarded.…”

Section: Methodsmentioning

confidence: 99%

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Long Term Synaptic Depression That Is Associated with GluR1 Dephosphorylation but Not α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid (AMPA) Receptor Internalization

Davies

Goebel-Goody

Coultrap

et al. 2008

Journal of Biological Chemistry

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Long lasting changes in the strength of synaptic transmission in the hippocampus are thought to underlie certain forms of learning and memory. Accordingly, the molecular mechanisms that account for these changes are heavily studied. Postsynaptically, changes in synaptic strength can occur by altering the amount of neurotransmitter receptors at the synapse or by altering the functional properties of synaptic receptors. In this study, we examined the biochemical changes produced following chemically induced long term depression in acute hippocampal CA1 minislices. Using three independent methods, we found that this treatment did not lead to an internalization of ␣-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors. Furthermore, when the plasma membrane was separated into synaptic membrane-enriched and extrasynaptic membrane-enriched fractions, we actually observed a significant increase in the concentration of AMPA receptors at the synapse. However, phosphorylation of Ser-845 on the AMPA receptor subunit GluR1 was significantly decreased throughout the neuron, including in the synaptic membrane-enriched fraction. In addition, phosphorylation of Ser-831 on GluR1 was decreased specifically in the synaptic membrane-enriched fraction. Phosphorylation of these residues has been demonstrated to control AMPA receptor function. From these data, we conclude that the decrease in synaptic strength is likely the result of a change in the functional properties of AMPA receptors at the synapse and not a decrease in the amount of synaptic receptors.Rapid excitatory synaptic transmission in the hippocampus is mediated predominantly by glutamate-activated AMPA 2 receptors (AMPARs). Theoretically, long term changes in the strength of synaptic transmission, as occur during long term potentiation and long term depression (LTD), can arise from changes in the amount of glutamate that is released from the presynaptic terminal, changes in the number of synaptic AMPARs, or changes in the functional properties of synaptic AMPARs. Experimentally, LTD of synaptic responses has been shown to be induced by several different treatments, the most common of which include several low frequency stimulation (LFS) paradigms (1), N-methyl-D-aspartate (NMDA) application (2), 3,5-dihydroxyphenylglycine application (3, 4), and insulin application (5). The biochemical mechanisms that underlie these different types of synaptic depression have been the subject of numerous studies in many different experimental systems.A number of studies have demonstrated that protein phosphatase activity is a requirement for long term depression. This was originally demonstrated through the use of protein phosphatase 1 (PP1), 2A (PP2A), and 2B (PP2B/calcineurin) inhibitors, which were shown to inhibit both the induction and the maintenance of LTD (6, 7). Furthermore, it has been suggested that synaptically localized PP1 is critical for the induction of LTD and that enhancing the synaptic targeting of PP1 facilitates long term depression (8). In addition, a...

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αCaMKII autophosphorylation levels differ depending on subcellular localization

Cited by 27 publications

References 69 publications

Mer receptor tyrosine kinase is a novel therapeutic target in pediatric B-cell acute lymphoblastic leukemia

Mer receptor tyrosine kinase is a novel therapeutic target in pediatric B-cell acute lymphoblastic leukemia

Enhanced long term potentiation and decreased AMPA receptor desensitization in the acute period following a single kainate induced early life seizure

Long Term Synaptic Depression That Is Associated with GluR1 Dephosphorylation but Not α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid (AMPA) Receptor Internalization

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