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Rapid Increases in proBDNF after Pilocarpine-Induced Status Epilepticus in Mice Are Associated with Reduced proBDNF Cleavage Machinery.

Thomas AX, Cruz Del Angel Y, Gonzalez MI, Carrel AJ, Carlsen J, Lam PM, Hempstead BL, Russek SJ, Brooks-Kayal AR - eNeuro (2016)

Bottom Line: In contrast to previous reports (Unsain et al., 2008; Volosin et al., 2008; VonDran et al., 2014), our studies found that levels of proBDNF in the hippocampus are markedly elevated as early as 3 h after SE onset and remain elevated for 7 d.In vitro treatment of hippocampal slices from animals 24 h after SE with a PAI-1 inhibitor reduces proBDNF levels.These findings suggest that rapid proBDNF increases following SE are due in part to reduced cleavage, and that proBDNF may be part of the initial neurotrophin response driving intracellular signaling during the acute phase of epileptogenesis.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045; Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045; Medical Scientist Training Program, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045.

ABSTRACT
Brain-derived neurotrophic factor (BDNF) levels are elevated after status epilepticus (SE), leading to activation of multiple signaling pathways, including the janus kinase/signal transducer and activator of transcription pathway that mediates a decrease in GABAA receptor α1 subunits in the hippocampus (Lund et al., 2008). While BDNF can signal via its pro or mature form, the relative contribution of these forms to signaling after SE is not fully known. In the current study, we investigate changes in proBDNF levels acutely after SE in C57BL/6J mice. In contrast to previous reports (Unsain et al., 2008; Volosin et al., 2008; VonDran et al., 2014), our studies found that levels of proBDNF in the hippocampus are markedly elevated as early as 3 h after SE onset and remain elevated for 7 d. Immunohistochemistry studies indicate that seizure-induced BDNF localizes to all hippocampal subfields, predominantly in principal neurons and also in astrocytes. Analysis of the proteolytic machinery that cleaves proBDNF to produce mature BDNF demonstrates that acutely after SE there is a decrease in tissue plasminogen activator and an increase in plasminogen activator inhibitor-1 (PAI-1), an inhibitor of extracellular and intracellular cleavage, which normalizes over the first week after SE. In vitro treatment of hippocampal slices from animals 24 h after SE with a PAI-1 inhibitor reduces proBDNF levels. These findings suggest that rapid proBDNF increases following SE are due in part to reduced cleavage, and that proBDNF may be part of the initial neurotrophin response driving intracellular signaling during the acute phase of epileptogenesis.

No MeSH data available.


Related in: MedlinePlus

ProBDNF, PAI-1, and tPA levels at 3 and 7 d following SE. A–C, Right, Representative Western blots of whole hippocampal protein homogenates from WT mice killed 3 d (top panels) or 7 d (bottom panels) after the induction of SE or time-matched saline controls probed with antibodies against proBDNF (A), PAI-1 (B), or tPA (C). Left, Densitometry analysis of abundance of proBDNF (A), PAI-1 (B), or tPA (C) normalized to actin and expressed as the percentage change relative to mean values of control group (±SEM). Anti-proBDNF (1:2000; A); anti-PAI-1 (1:1000; B); and anti-tPA (1:11,000; C). N = 4 for all control groups, and N = 8 for all 7 d SE groups. For 3 d SE groups, N = 4 for proBDNF and N = 5 for PAI-1 and tPA (*p < 0.05, ***p < 0.001; t test was used for all analyses except PAI at 3 d, for which the Mann–Whitney (nonparametric) test was used due to a non-normal dataset).
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Figure 7: ProBDNF, PAI-1, and tPA levels at 3 and 7 d following SE. A–C, Right, Representative Western blots of whole hippocampal protein homogenates from WT mice killed 3 d (top panels) or 7 d (bottom panels) after the induction of SE or time-matched saline controls probed with antibodies against proBDNF (A), PAI-1 (B), or tPA (C). Left, Densitometry analysis of abundance of proBDNF (A), PAI-1 (B), or tPA (C) normalized to actin and expressed as the percentage change relative to mean values of control group (±SEM). Anti-proBDNF (1:2000; A); anti-PAI-1 (1:1000; B); and anti-tPA (1:11,000; C). N = 4 for all control groups, and N = 8 for all 7 d SE groups. For 3 d SE groups, N = 4 for proBDNF and N = 5 for PAI-1 and tPA (*p < 0.05, ***p < 0.001; t test was used for all analyses except PAI at 3 d, for which the Mann–Whitney (nonparametric) test was used due to a non-normal dataset).

Mentions: Statistics


Rapid Increases in proBDNF after Pilocarpine-Induced Status Epilepticus in Mice Are Associated with Reduced proBDNF Cleavage Machinery.

Thomas AX, Cruz Del Angel Y, Gonzalez MI, Carrel AJ, Carlsen J, Lam PM, Hempstead BL, Russek SJ, Brooks-Kayal AR - eNeuro (2016)

ProBDNF, PAI-1, and tPA levels at 3 and 7 d following SE. A–C, Right, Representative Western blots of whole hippocampal protein homogenates from WT mice killed 3 d (top panels) or 7 d (bottom panels) after the induction of SE or time-matched saline controls probed with antibodies against proBDNF (A), PAI-1 (B), or tPA (C). Left, Densitometry analysis of abundance of proBDNF (A), PAI-1 (B), or tPA (C) normalized to actin and expressed as the percentage change relative to mean values of control group (±SEM). Anti-proBDNF (1:2000; A); anti-PAI-1 (1:1000; B); and anti-tPA (1:11,000; C). N = 4 for all control groups, and N = 8 for all 7 d SE groups. For 3 d SE groups, N = 4 for proBDNF and N = 5 for PAI-1 and tPA (*p < 0.05, ***p < 0.001; t test was used for all analyses except PAI at 3 d, for which the Mann–Whitney (nonparametric) test was used due to a non-normal dataset).
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4814566&req=5

Figure 7: ProBDNF, PAI-1, and tPA levels at 3 and 7 d following SE. A–C, Right, Representative Western blots of whole hippocampal protein homogenates from WT mice killed 3 d (top panels) or 7 d (bottom panels) after the induction of SE or time-matched saline controls probed with antibodies against proBDNF (A), PAI-1 (B), or tPA (C). Left, Densitometry analysis of abundance of proBDNF (A), PAI-1 (B), or tPA (C) normalized to actin and expressed as the percentage change relative to mean values of control group (±SEM). Anti-proBDNF (1:2000; A); anti-PAI-1 (1:1000; B); and anti-tPA (1:11,000; C). N = 4 for all control groups, and N = 8 for all 7 d SE groups. For 3 d SE groups, N = 4 for proBDNF and N = 5 for PAI-1 and tPA (*p < 0.05, ***p < 0.001; t test was used for all analyses except PAI at 3 d, for which the Mann–Whitney (nonparametric) test was used due to a non-normal dataset).
Mentions: Statistics

Bottom Line: In contrast to previous reports (Unsain et al., 2008; Volosin et al., 2008; VonDran et al., 2014), our studies found that levels of proBDNF in the hippocampus are markedly elevated as early as 3 h after SE onset and remain elevated for 7 d.In vitro treatment of hippocampal slices from animals 24 h after SE with a PAI-1 inhibitor reduces proBDNF levels.These findings suggest that rapid proBDNF increases following SE are due in part to reduced cleavage, and that proBDNF may be part of the initial neurotrophin response driving intracellular signaling during the acute phase of epileptogenesis.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045; Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045; Medical Scientist Training Program, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045.

ABSTRACT
Brain-derived neurotrophic factor (BDNF) levels are elevated after status epilepticus (SE), leading to activation of multiple signaling pathways, including the janus kinase/signal transducer and activator of transcription pathway that mediates a decrease in GABAA receptor α1 subunits in the hippocampus (Lund et al., 2008). While BDNF can signal via its pro or mature form, the relative contribution of these forms to signaling after SE is not fully known. In the current study, we investigate changes in proBDNF levels acutely after SE in C57BL/6J mice. In contrast to previous reports (Unsain et al., 2008; Volosin et al., 2008; VonDran et al., 2014), our studies found that levels of proBDNF in the hippocampus are markedly elevated as early as 3 h after SE onset and remain elevated for 7 d. Immunohistochemistry studies indicate that seizure-induced BDNF localizes to all hippocampal subfields, predominantly in principal neurons and also in astrocytes. Analysis of the proteolytic machinery that cleaves proBDNF to produce mature BDNF demonstrates that acutely after SE there is a decrease in tissue plasminogen activator and an increase in plasminogen activator inhibitor-1 (PAI-1), an inhibitor of extracellular and intracellular cleavage, which normalizes over the first week after SE. In vitro treatment of hippocampal slices from animals 24 h after SE with a PAI-1 inhibitor reduces proBDNF levels. These findings suggest that rapid proBDNF increases following SE are due in part to reduced cleavage, and that proBDNF may be part of the initial neurotrophin response driving intracellular signaling during the acute phase of epileptogenesis.

No MeSH data available.


Related in: MedlinePlus