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Abelson tyrosine kinase links PDGFbeta receptor activation to cytoskeletal regulation of NMDA receptors in CA1 hippocampal neurons.

Beazely MA, Weerapura M, MacDonald JF - Mol Brain (2008)

Bottom Line: Intracellular applications of active Abl, but not heat-inactivated Abl, decreased NMDA-evoked currents in isolated hippocampal neurons.This mimics the effects of PDGF receptor activation in these neurons.This study demonstrates that PDGFβ receptors act via an interaction with Abl kinase and Rho kinase to regulated cytoskeletal regulation of NMDA receptor channels in CA1 pyramidal neurons.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physiology, University of Toronto, ON, Canada. mbeazely@uwaterloo.ca

ABSTRACT

Background: We have previously demonstrated that PDGF receptor activation indirectly inhibits N-methyl-D-aspartate (NMDA) currents by modifying the cytoskeleton. PDGF receptor ligand is also neuroprotective in hippocampal slices and cultured neurons. PDGF receptors are tyrosine kinases that control a variety of signal transduction pathways including those mediated by PLCγ. In fibroblasts Src and another non-receptor tyrosine kinase, Abelson kinase (Abl), control PDGF receptor regulation of cytoskeletal dynamics. The mechanism whereby PDGF receptor regulates cytoskeletal dynamics in central neurons remains poorly understood.

Results: Intracellular applications of active Abl, but not heat-inactivated Abl, decreased NMDA-evoked currents in isolated hippocampal neurons. This mimics the effects of PDGF receptor activation in these neurons. The Abl kinase inhibitor, STI571, blocked the inhibition of NMDA currents by Abl. We demonstrate that PDGF receptors can activate Abl kinase in hippocampal neurons via mechanisms similar to those observed previously in fibroblasts. Furthermore, PDGFβ receptor activation alters the subcellular localization of Abl. Abl kinase is linked to actin cytoskeletal dynamics in many systems. We show that the inhibition of NMDA receptor currents by Abl kinase is blocked by the inclusion of the Rho kinase inhibitor, Y-27632, and that activation of Abl correlates with an increase in ROCK tyrosine phosphorylation.

Conclusion: This study demonstrates that PDGFβ receptors act via an interaction with Abl kinase and Rho kinase to regulated cytoskeletal regulation of NMDA receptor channels in CA1 pyramidal neurons.

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Intracellular application of Abl decreases NMDA-evoked currents. A) Active (black square) or heat-inactivated (denat., white square) Abl kinase (0.5 μg/mL) was included in the intracellular solution. NMDA-evoked currents were recorded once every minute and peak currents were normalized to the average of the first five currents recorded. At 25 minutes (b) Abl significantly reduced NMDA-evoked currents (p < 0.05, Student's t-test, n = 6). B, C) Representative currents from currents recorded in the presence of active Abl kinase or heat-inactivated kinase at t = 3 minutes (a) or t = 25 minutes (b). D) NMDA-evoked currents were recorded with active Abl kinase applied intracellularly in the ICF in the absence (black square) or presence (black triangle) of the Abl kinase inhibitor, STI571, applied in the ECF bath (n = 6). E) NMDA-evoked currents were recorded with active Abl kinase applied intracellularly in the ICF in the absence (black square) or presence (black triangle) of the Abl kinase inhibitor, STI571, applied in the ECF bath for 25 minutes (STI571), followed by a 25 minute washout period (WO) during which control ECF solution was applied (n = 6).
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Figure 1: Intracellular application of Abl decreases NMDA-evoked currents. A) Active (black square) or heat-inactivated (denat., white square) Abl kinase (0.5 μg/mL) was included in the intracellular solution. NMDA-evoked currents were recorded once every minute and peak currents were normalized to the average of the first five currents recorded. At 25 minutes (b) Abl significantly reduced NMDA-evoked currents (p < 0.05, Student's t-test, n = 6). B, C) Representative currents from currents recorded in the presence of active Abl kinase or heat-inactivated kinase at t = 3 minutes (a) or t = 25 minutes (b). D) NMDA-evoked currents were recorded with active Abl kinase applied intracellularly in the ICF in the absence (black square) or presence (black triangle) of the Abl kinase inhibitor, STI571, applied in the ECF bath (n = 6). E) NMDA-evoked currents were recorded with active Abl kinase applied intracellularly in the ICF in the absence (black square) or presence (black triangle) of the Abl kinase inhibitor, STI571, applied in the ECF bath for 25 minutes (STI571), followed by a 25 minute washout period (WO) during which control ECF solution was applied (n = 6).

Mentions: To examine the effects of Abl on NMDA currents, we acutely dissociated CA1 neurons from 2–3 week old Wistar rats. Whole cell NMDA currents were evoked by applying 50 μM NMDA and 0.5 μM glycine for 2 seconds every minute. Intracellular application of 0.5 μg/mL active Abl kinase resulted in a time-dependent depression of NMDA currents (Figure 1A). After 25 minutes, NMDA currents were reduced by 53 ± 5% (Figure 1A, B). In contrast, the inclusion of heat-inactivated Abl kinase in the patch pipette did not depress NMDA currents such that peak currents were maintained for the 25 minutes of recording (104 ± 8%, Figure 1A, C).


Abelson tyrosine kinase links PDGFbeta receptor activation to cytoskeletal regulation of NMDA receptors in CA1 hippocampal neurons.

Beazely MA, Weerapura M, MacDonald JF - Mol Brain (2008)

Intracellular application of Abl decreases NMDA-evoked currents. A) Active (black square) or heat-inactivated (denat., white square) Abl kinase (0.5 μg/mL) was included in the intracellular solution. NMDA-evoked currents were recorded once every minute and peak currents were normalized to the average of the first five currents recorded. At 25 minutes (b) Abl significantly reduced NMDA-evoked currents (p < 0.05, Student's t-test, n = 6). B, C) Representative currents from currents recorded in the presence of active Abl kinase or heat-inactivated kinase at t = 3 minutes (a) or t = 25 minutes (b). D) NMDA-evoked currents were recorded with active Abl kinase applied intracellularly in the ICF in the absence (black square) or presence (black triangle) of the Abl kinase inhibitor, STI571, applied in the ECF bath (n = 6). E) NMDA-evoked currents were recorded with active Abl kinase applied intracellularly in the ICF in the absence (black square) or presence (black triangle) of the Abl kinase inhibitor, STI571, applied in the ECF bath for 25 minutes (STI571), followed by a 25 minute washout period (WO) during which control ECF solution was applied (n = 6).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2651131&req=5

Figure 1: Intracellular application of Abl decreases NMDA-evoked currents. A) Active (black square) or heat-inactivated (denat., white square) Abl kinase (0.5 μg/mL) was included in the intracellular solution. NMDA-evoked currents were recorded once every minute and peak currents were normalized to the average of the first five currents recorded. At 25 minutes (b) Abl significantly reduced NMDA-evoked currents (p < 0.05, Student's t-test, n = 6). B, C) Representative currents from currents recorded in the presence of active Abl kinase or heat-inactivated kinase at t = 3 minutes (a) or t = 25 minutes (b). D) NMDA-evoked currents were recorded with active Abl kinase applied intracellularly in the ICF in the absence (black square) or presence (black triangle) of the Abl kinase inhibitor, STI571, applied in the ECF bath (n = 6). E) NMDA-evoked currents were recorded with active Abl kinase applied intracellularly in the ICF in the absence (black square) or presence (black triangle) of the Abl kinase inhibitor, STI571, applied in the ECF bath for 25 minutes (STI571), followed by a 25 minute washout period (WO) during which control ECF solution was applied (n = 6).
Mentions: To examine the effects of Abl on NMDA currents, we acutely dissociated CA1 neurons from 2–3 week old Wistar rats. Whole cell NMDA currents were evoked by applying 50 μM NMDA and 0.5 μM glycine for 2 seconds every minute. Intracellular application of 0.5 μg/mL active Abl kinase resulted in a time-dependent depression of NMDA currents (Figure 1A). After 25 minutes, NMDA currents were reduced by 53 ± 5% (Figure 1A, B). In contrast, the inclusion of heat-inactivated Abl kinase in the patch pipette did not depress NMDA currents such that peak currents were maintained for the 25 minutes of recording (104 ± 8%, Figure 1A, C).

Bottom Line: Intracellular applications of active Abl, but not heat-inactivated Abl, decreased NMDA-evoked currents in isolated hippocampal neurons.This mimics the effects of PDGF receptor activation in these neurons.This study demonstrates that PDGFβ receptors act via an interaction with Abl kinase and Rho kinase to regulated cytoskeletal regulation of NMDA receptor channels in CA1 pyramidal neurons.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physiology, University of Toronto, ON, Canada. mbeazely@uwaterloo.ca

ABSTRACT

Background: We have previously demonstrated that PDGF receptor activation indirectly inhibits N-methyl-D-aspartate (NMDA) currents by modifying the cytoskeleton. PDGF receptor ligand is also neuroprotective in hippocampal slices and cultured neurons. PDGF receptors are tyrosine kinases that control a variety of signal transduction pathways including those mediated by PLCγ. In fibroblasts Src and another non-receptor tyrosine kinase, Abelson kinase (Abl), control PDGF receptor regulation of cytoskeletal dynamics. The mechanism whereby PDGF receptor regulates cytoskeletal dynamics in central neurons remains poorly understood.

Results: Intracellular applications of active Abl, but not heat-inactivated Abl, decreased NMDA-evoked currents in isolated hippocampal neurons. This mimics the effects of PDGF receptor activation in these neurons. The Abl kinase inhibitor, STI571, blocked the inhibition of NMDA currents by Abl. We demonstrate that PDGF receptors can activate Abl kinase in hippocampal neurons via mechanisms similar to those observed previously in fibroblasts. Furthermore, PDGFβ receptor activation alters the subcellular localization of Abl. Abl kinase is linked to actin cytoskeletal dynamics in many systems. We show that the inhibition of NMDA receptor currents by Abl kinase is blocked by the inclusion of the Rho kinase inhibitor, Y-27632, and that activation of Abl correlates with an increase in ROCK tyrosine phosphorylation.

Conclusion: This study demonstrates that PDGFβ receptors act via an interaction with Abl kinase and Rho kinase to regulated cytoskeletal regulation of NMDA receptor channels in CA1 pyramidal neurons.

Show MeSH
Related in: MedlinePlus