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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 levels are elevated in BDNF-HA-tagged mice in the first 24 h after pilocarpine-induced SE. A, Top, Representative Western blot of whole hippocampal protein homogenates from BDNF-HA mice killed 3 h after the induction of SE or time-matched saline controls probed with anti-HA (1:3000) and anti-actin antibodies. Bottom, Densitometry analysis of proBDNF protein abundance. Ratio of proBDNF/actin at 3 h after SE (N = 6) expressed as the percentage change relative to mean values (±SEM) of the control group (N = 3; **p < 0.001). B, Top, Representative Western blot of whole hippocampal protein homogenates from BDNF-HA mice probed with anti-HA (1:3000) and anti-actin antibodies killed 24 h after the induction of SE or time-matched saline controls. Bottom, Densitometry analysis of proBDNF protein abundance at 24 h after SE. Ratio of proBDNF/actin at 24 h post-SE (N = 6) expressed as the percentage change relative to mean values of control group (N = 3; **p < 0.01). Densitometry analysis of mBDNF protein abundance (mBDNF/actin) showed no significant difference between the control and SE group at either time point.
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Figure 3: ProBDNF levels are elevated in BDNF-HA-tagged mice in the first 24 h after pilocarpine-induced SE. A, Top, Representative Western blot of whole hippocampal protein homogenates from BDNF-HA mice killed 3 h after the induction of SE or time-matched saline controls probed with anti-HA (1:3000) and anti-actin antibodies. Bottom, Densitometry analysis of proBDNF protein abundance. Ratio of proBDNF/actin at 3 h after SE (N = 6) expressed as the percentage change relative to mean values (±SEM) of the control group (N = 3; **p < 0.001). B, Top, Representative Western blot of whole hippocampal protein homogenates from BDNF-HA mice probed with anti-HA (1:3000) and anti-actin antibodies killed 24 h after the induction of SE or time-matched saline controls. Bottom, Densitometry analysis of proBDNF protein abundance at 24 h after SE. Ratio of proBDNF/actin at 24 h post-SE (N = 6) expressed as the percentage change relative to mean values of control group (N = 3; **p < 0.01). Densitometry analysis of mBDNF protein abundance (mBDNF/actin) showed no significant difference between the control and SE group at either time point.

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 levels are elevated in BDNF-HA-tagged mice in the first 24 h after pilocarpine-induced SE. A, Top, Representative Western blot of whole hippocampal protein homogenates from BDNF-HA mice killed 3 h after the induction of SE or time-matched saline controls probed with anti-HA (1:3000) and anti-actin antibodies. Bottom, Densitometry analysis of proBDNF protein abundance. Ratio of proBDNF/actin at 3 h after SE (N = 6) expressed as the percentage change relative to mean values (±SEM) of the control group (N = 3; **p < 0.001). B, Top, Representative Western blot of whole hippocampal protein homogenates from BDNF-HA mice probed with anti-HA (1:3000) and anti-actin antibodies killed 24 h after the induction of SE or time-matched saline controls. Bottom, Densitometry analysis of proBDNF protein abundance at 24 h after SE. Ratio of proBDNF/actin at 24 h post-SE (N = 6) expressed as the percentage change relative to mean values of control group (N = 3; **p < 0.01). Densitometry analysis of mBDNF protein abundance (mBDNF/actin) showed no significant difference between the control and SE group at either time point.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: ProBDNF levels are elevated in BDNF-HA-tagged mice in the first 24 h after pilocarpine-induced SE. A, Top, Representative Western blot of whole hippocampal protein homogenates from BDNF-HA mice killed 3 h after the induction of SE or time-matched saline controls probed with anti-HA (1:3000) and anti-actin antibodies. Bottom, Densitometry analysis of proBDNF protein abundance. Ratio of proBDNF/actin at 3 h after SE (N = 6) expressed as the percentage change relative to mean values (±SEM) of the control group (N = 3; **p < 0.001). B, Top, Representative Western blot of whole hippocampal protein homogenates from BDNF-HA mice probed with anti-HA (1:3000) and anti-actin antibodies killed 24 h after the induction of SE or time-matched saline controls. Bottom, Densitometry analysis of proBDNF protein abundance at 24 h after SE. Ratio of proBDNF/actin at 24 h post-SE (N = 6) expressed as the percentage change relative to mean values of control group (N = 3; **p < 0.01). Densitometry analysis of mBDNF protein abundance (mBDNF/actin) showed no significant difference between the control and SE group at either time point.
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