Limits...
RanBP9 at the intersection between cofilin and Aβ pathologies: rescue of neurodegenerative changes by RanBP9 reduction.

Woo JA, Boggess T, Uhlar C, Wang X, Khan H, Cappos G, Joly-Amado A, De Narvaez E, Majid S, Minamide LS, Bamburg JR, Morgan D, Weeber E, Kang DE - Cell Death Dis (2015)

Bottom Line: In this study, we found that endogenous RanBP9 positively regulates SSH1 levels and mediates Aβ-induced translocation of cofilin to mitochondria and induction of cofilin-actin pathology in cultured cells, primary neurons, and in vivo.Endogenous level of RanBP9 was also required for Aβ-induced collapse of growth cones in immature neurons (days in vitro 9 (DIV9)) and depletion of synaptic proteins in mature neurons (DIV21).Therefore, these results underscore the critical importance of endogenous RanBP9 not only in Aβ accumulation but also in mediating the neurotoxic actions of Aβ at the level of synaptic plasticity, mitochondria, and cofilin-actin pathology via control of the SSH1-cofilin pathway in vivo.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Medicine, USF Health Byrd Alzheimer's Institute, Tampa, FL, USA.

ABSTRACT
Molecular pathways underlying the neurotoxicity and production of amyloid β protein (Aβ) represent potentially promising therapeutic targets for Alzheimer's disease (AD). We recently found that overexpression of the scaffolding protein RanBP9 increases Aβ production in cell lines and in transgenic mice while promoting cofilin activation and mitochondrial dysfunction. Translocation of cofilin to mitochondria and induction of cofilin-actin pathology require the activation/dephosphorylation of cofilin by Slingshot homolog 1 (SSH1) and cysteine oxidation of cofilin. In this study, we found that endogenous RanBP9 positively regulates SSH1 levels and mediates Aβ-induced translocation of cofilin to mitochondria and induction of cofilin-actin pathology in cultured cells, primary neurons, and in vivo. Endogenous level of RanBP9 was also required for Aβ-induced collapse of growth cones in immature neurons (days in vitro 9 (DIV9)) and depletion of synaptic proteins in mature neurons (DIV21). In vivo, amyloid precursor protein (APP)/presenilin-1 (PS1) mice exhibited 3.5-fold increased RanBP9 levels, and RanBP9 reduction protected against cofilin-actin pathology, synaptic damage, gliosis, and Aβ accumulation associated with APP/PS1 mice. Brains slices derived from APP/PS1 mice showed significantly impaired long-term potentiation (LTP), and RanBP9 reduction significantly enhanced paired pulse facilitation and LTP, as well as partially rescued contextual memory deficits associated with APP/PS1 mice. Therefore, these results underscore the critical importance of endogenous RanBP9 not only in Aβ accumulation but also in mediating the neurotoxic actions of Aβ at the level of synaptic plasticity, mitochondria, and cofilin-actin pathology via control of the SSH1-cofilin pathway in vivo.

Show MeSH

Related in: MedlinePlus

Rescue of synaptic plasticity and contextual memory impairments in APP/PS1 mice by RanBP9 reduction. (a-c) Stimulating electrode placed in the Schaffer collaterals of the hippocampus and recording glass electrode positioned at the CA1 stratum radiatum below the pyramidal cell layer. (a) Input–output analysis performed by stepping up stimulation amplitude from 1–15mV in WT, APP/PS1, RanBP9+/−, and APP/PS1;RanBP9+/− acute slices. No significant differences observed. Slices from WT n=45, RanBP9+/− n=31, APP/PS1 n=19, APP/PS1;RanBP9+/− n=25; slices derived from four to six mice per genotype. (b) PPF showing significant differences among all interstimulus intervals (two-way ANOVA, genotype: P<0.0001; interstimulus interval: P<0.0001; interaction: P=0.0122). Post-hoc Tukey test shows significant increases in fEPSP slope in APP/PS1;RanBP9+/− slices compared with WT, RanBP9+/−, and APP/PS1 slices at nearly all interstimulus intervals (P<0.05 to P<0.0001). Slices from WT n=49, RanBP9+/− n=33. APP/PS1 n=31, APP/PS1;RanBP9+/− n=25; slices derived from four to six mice per genotype. (c) No significant changes between genotypes at baseline before LTP but LTP induced by theta burst stimulation showing significant differences in fEPSP slope among WT, APP/PS1, RanBP9+/−, and APP/PS1;RanBP9+/− slices (two-way ANOVA, genotype: P<0.0001; time: P<0.0001; interaction: P<0.0001). Post-hoc Tukey test shows significant differences between all genotypes at all time points after theta burst stimulation (P<0.0001) except between RanBP9+/− versus APP/PS1;RanBP9+/−. Slices from WT n=41, RanBP9+/− n=28, APP/PS1 n=33, APP/PS1;RanBP9+/− n=29; slices derived from four to six mice per genotype. (d) Quantitation of contextual fear conditioning (FC) freezing times (sec) after training session 24 h earlier across genotypes. Kruskal–Wallis ANOVA, post-hoc Dunn's, *P<0.05, WT n=12 (5 F and 7 M), APP/PS1 n=8 (4 F and 4 M), APP/PS1;RanBP9+/− n=6 (3 F and 3 M). (e) Quantitation of cued fear conditioning (FC) freezing times (sec) across genotypes (no significant differences by Kruskal–Wallis test or one-way ANOVA). Same number and gender as contextual FC. (f) Quantitation of open field activity test (total distance traveled over two- day training sessions) across genotypes (no significant differences by Kruskal–Wallis test or one-way ANOVA). Same numbers and gender as contextual FC. (g) Quantitation of rotarod test (time staying on rotarod) across genotypes (no significant differences by Kruskal–Wallis test or one-way ANOVA). Error bars represent S.E.M. in graphs. Same number and gender as contextual FC
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC4385917&req=5

fig8: Rescue of synaptic plasticity and contextual memory impairments in APP/PS1 mice by RanBP9 reduction. (a-c) Stimulating electrode placed in the Schaffer collaterals of the hippocampus and recording glass electrode positioned at the CA1 stratum radiatum below the pyramidal cell layer. (a) Input–output analysis performed by stepping up stimulation amplitude from 1–15mV in WT, APP/PS1, RanBP9+/−, and APP/PS1;RanBP9+/− acute slices. No significant differences observed. Slices from WT n=45, RanBP9+/− n=31, APP/PS1 n=19, APP/PS1;RanBP9+/− n=25; slices derived from four to six mice per genotype. (b) PPF showing significant differences among all interstimulus intervals (two-way ANOVA, genotype: P<0.0001; interstimulus interval: P<0.0001; interaction: P=0.0122). Post-hoc Tukey test shows significant increases in fEPSP slope in APP/PS1;RanBP9+/− slices compared with WT, RanBP9+/−, and APP/PS1 slices at nearly all interstimulus intervals (P<0.05 to P<0.0001). Slices from WT n=49, RanBP9+/− n=33. APP/PS1 n=31, APP/PS1;RanBP9+/− n=25; slices derived from four to six mice per genotype. (c) No significant changes between genotypes at baseline before LTP but LTP induced by theta burst stimulation showing significant differences in fEPSP slope among WT, APP/PS1, RanBP9+/−, and APP/PS1;RanBP9+/− slices (two-way ANOVA, genotype: P<0.0001; time: P<0.0001; interaction: P<0.0001). Post-hoc Tukey test shows significant differences between all genotypes at all time points after theta burst stimulation (P<0.0001) except between RanBP9+/− versus APP/PS1;RanBP9+/−. Slices from WT n=41, RanBP9+/− n=28, APP/PS1 n=33, APP/PS1;RanBP9+/− n=29; slices derived from four to six mice per genotype. (d) Quantitation of contextual fear conditioning (FC) freezing times (sec) after training session 24 h earlier across genotypes. Kruskal–Wallis ANOVA, post-hoc Dunn's, *P<0.05, WT n=12 (5 F and 7 M), APP/PS1 n=8 (4 F and 4 M), APP/PS1;RanBP9+/− n=6 (3 F and 3 M). (e) Quantitation of cued fear conditioning (FC) freezing times (sec) across genotypes (no significant differences by Kruskal–Wallis test or one-way ANOVA). Same number and gender as contextual FC. (f) Quantitation of open field activity test (total distance traveled over two- day training sessions) across genotypes (no significant differences by Kruskal–Wallis test or one-way ANOVA). Same numbers and gender as contextual FC. (g) Quantitation of rotarod test (time staying on rotarod) across genotypes (no significant differences by Kruskal–Wallis test or one-way ANOVA). Error bars represent S.E.M. in graphs. Same number and gender as contextual FC

Mentions: We tested short-term and long-term synaptic plasticity from acute hippocampal slices prepared from 3-month-old WT, APP/PS1, RanBP9+/−, and APP/PS1;RanBP9+/− mice, an age when little to no Aβ plaques are detected.22 The stimulating electrode was placed in the Schaffer collaterals of the hippocampus, and the recording electrode was positioned at the CA1 stratum radiatum below the pyramidal cell layer. As shown in Figure 8a, input–output analysis did not markedly differ among WT, APP/PS1, and APP/PS1;RanBP9+/−, and RanBP9+/−slices. However, the APP/PS1;RanBP9+/− slices showed a nonsignificant decrease in basal synaptic transmission compared with WT, RanBP9+/−, and APP/PS1 slices (Figure 8a). In paired pulse facilitation (PPF) experiments, significant differences were observed in fEPSP slope across genotypes among all interstimulus intervals (Figure 8b). Correction for multiple comparisons surprisingly showed that APP/PS1;RanBP9+/− slices exhibited significantly higher PPF compared with both WT, RanBP9+/−, and APP/PS1 slices across most interstimulus intervals (Figure 8b), indicating a synergistic effect of RanBP9 and APP/PS1 genotypes on cooperative presynaptic efficacy. For long-term potentiation (LTP) measurements, we detected no differences in fEPSP slope among WT, APP/PS1, RanBP9+/−, and APP/PS1;RanBP9+/− slices at baseline (Figure 8c). However, after theta burst stimulation, we observed significant differences in fEPSP slope across genotypes for all time points (Figure 8c). Correction for multiple comparisons showed that APP/PS1 slices were significantly impaired in fEPSP slope compared with WT, RanBP9+/−, and APP/PS1;RanBP9+/− slices at every time point up to 1 h (Figure 8c). APP/PS1;RanBP9+/− slices exhibited significantly stronger fEPSP slope across all time points compared with WT and APP/PS1 slices (Figure 8c), indicating that RanBP9 reduction greatly enhances both the induction and maintenance of LTP. Similarly, RanBP9+/− slices exhibited significantly stronger LTP than WT slices up to 30 min and did not significantly differ from APP/PS1;RanBP9+/− slices (Figure 8c). Therefore, these results indicate that RanBP9 reduction not only rescues the deficits in synaptic plasticity associated with the APP/PS1 mice but also further potentiates synaptic plasticity.


RanBP9 at the intersection between cofilin and Aβ pathologies: rescue of neurodegenerative changes by RanBP9 reduction.

Woo JA, Boggess T, Uhlar C, Wang X, Khan H, Cappos G, Joly-Amado A, De Narvaez E, Majid S, Minamide LS, Bamburg JR, Morgan D, Weeber E, Kang DE - Cell Death Dis (2015)

Rescue of synaptic plasticity and contextual memory impairments in APP/PS1 mice by RanBP9 reduction. (a-c) Stimulating electrode placed in the Schaffer collaterals of the hippocampus and recording glass electrode positioned at the CA1 stratum radiatum below the pyramidal cell layer. (a) Input–output analysis performed by stepping up stimulation amplitude from 1–15mV in WT, APP/PS1, RanBP9+/−, and APP/PS1;RanBP9+/− acute slices. No significant differences observed. Slices from WT n=45, RanBP9+/− n=31, APP/PS1 n=19, APP/PS1;RanBP9+/− n=25; slices derived from four to six mice per genotype. (b) PPF showing significant differences among all interstimulus intervals (two-way ANOVA, genotype: P<0.0001; interstimulus interval: P<0.0001; interaction: P=0.0122). Post-hoc Tukey test shows significant increases in fEPSP slope in APP/PS1;RanBP9+/− slices compared with WT, RanBP9+/−, and APP/PS1 slices at nearly all interstimulus intervals (P<0.05 to P<0.0001). Slices from WT n=49, RanBP9+/− n=33. APP/PS1 n=31, APP/PS1;RanBP9+/− n=25; slices derived from four to six mice per genotype. (c) No significant changes between genotypes at baseline before LTP but LTP induced by theta burst stimulation showing significant differences in fEPSP slope among WT, APP/PS1, RanBP9+/−, and APP/PS1;RanBP9+/− slices (two-way ANOVA, genotype: P<0.0001; time: P<0.0001; interaction: P<0.0001). Post-hoc Tukey test shows significant differences between all genotypes at all time points after theta burst stimulation (P<0.0001) except between RanBP9+/− versus APP/PS1;RanBP9+/−. Slices from WT n=41, RanBP9+/− n=28, APP/PS1 n=33, APP/PS1;RanBP9+/− n=29; slices derived from four to six mice per genotype. (d) Quantitation of contextual fear conditioning (FC) freezing times (sec) after training session 24 h earlier across genotypes. Kruskal–Wallis ANOVA, post-hoc Dunn's, *P<0.05, WT n=12 (5 F and 7 M), APP/PS1 n=8 (4 F and 4 M), APP/PS1;RanBP9+/− n=6 (3 F and 3 M). (e) Quantitation of cued fear conditioning (FC) freezing times (sec) across genotypes (no significant differences by Kruskal–Wallis test or one-way ANOVA). Same number and gender as contextual FC. (f) Quantitation of open field activity test (total distance traveled over two- day training sessions) across genotypes (no significant differences by Kruskal–Wallis test or one-way ANOVA). Same numbers and gender as contextual FC. (g) Quantitation of rotarod test (time staying on rotarod) across genotypes (no significant differences by Kruskal–Wallis test or one-way ANOVA). Error bars represent S.E.M. in graphs. Same number and gender as contextual FC
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4385917&req=5

fig8: Rescue of synaptic plasticity and contextual memory impairments in APP/PS1 mice by RanBP9 reduction. (a-c) Stimulating electrode placed in the Schaffer collaterals of the hippocampus and recording glass electrode positioned at the CA1 stratum radiatum below the pyramidal cell layer. (a) Input–output analysis performed by stepping up stimulation amplitude from 1–15mV in WT, APP/PS1, RanBP9+/−, and APP/PS1;RanBP9+/− acute slices. No significant differences observed. Slices from WT n=45, RanBP9+/− n=31, APP/PS1 n=19, APP/PS1;RanBP9+/− n=25; slices derived from four to six mice per genotype. (b) PPF showing significant differences among all interstimulus intervals (two-way ANOVA, genotype: P<0.0001; interstimulus interval: P<0.0001; interaction: P=0.0122). Post-hoc Tukey test shows significant increases in fEPSP slope in APP/PS1;RanBP9+/− slices compared with WT, RanBP9+/−, and APP/PS1 slices at nearly all interstimulus intervals (P<0.05 to P<0.0001). Slices from WT n=49, RanBP9+/− n=33. APP/PS1 n=31, APP/PS1;RanBP9+/− n=25; slices derived from four to six mice per genotype. (c) No significant changes between genotypes at baseline before LTP but LTP induced by theta burst stimulation showing significant differences in fEPSP slope among WT, APP/PS1, RanBP9+/−, and APP/PS1;RanBP9+/− slices (two-way ANOVA, genotype: P<0.0001; time: P<0.0001; interaction: P<0.0001). Post-hoc Tukey test shows significant differences between all genotypes at all time points after theta burst stimulation (P<0.0001) except between RanBP9+/− versus APP/PS1;RanBP9+/−. Slices from WT n=41, RanBP9+/− n=28, APP/PS1 n=33, APP/PS1;RanBP9+/− n=29; slices derived from four to six mice per genotype. (d) Quantitation of contextual fear conditioning (FC) freezing times (sec) after training session 24 h earlier across genotypes. Kruskal–Wallis ANOVA, post-hoc Dunn's, *P<0.05, WT n=12 (5 F and 7 M), APP/PS1 n=8 (4 F and 4 M), APP/PS1;RanBP9+/− n=6 (3 F and 3 M). (e) Quantitation of cued fear conditioning (FC) freezing times (sec) across genotypes (no significant differences by Kruskal–Wallis test or one-way ANOVA). Same number and gender as contextual FC. (f) Quantitation of open field activity test (total distance traveled over two- day training sessions) across genotypes (no significant differences by Kruskal–Wallis test or one-way ANOVA). Same numbers and gender as contextual FC. (g) Quantitation of rotarod test (time staying on rotarod) across genotypes (no significant differences by Kruskal–Wallis test or one-way ANOVA). Error bars represent S.E.M. in graphs. Same number and gender as contextual FC
Mentions: We tested short-term and long-term synaptic plasticity from acute hippocampal slices prepared from 3-month-old WT, APP/PS1, RanBP9+/−, and APP/PS1;RanBP9+/− mice, an age when little to no Aβ plaques are detected.22 The stimulating electrode was placed in the Schaffer collaterals of the hippocampus, and the recording electrode was positioned at the CA1 stratum radiatum below the pyramidal cell layer. As shown in Figure 8a, input–output analysis did not markedly differ among WT, APP/PS1, and APP/PS1;RanBP9+/−, and RanBP9+/−slices. However, the APP/PS1;RanBP9+/− slices showed a nonsignificant decrease in basal synaptic transmission compared with WT, RanBP9+/−, and APP/PS1 slices (Figure 8a). In paired pulse facilitation (PPF) experiments, significant differences were observed in fEPSP slope across genotypes among all interstimulus intervals (Figure 8b). Correction for multiple comparisons surprisingly showed that APP/PS1;RanBP9+/− slices exhibited significantly higher PPF compared with both WT, RanBP9+/−, and APP/PS1 slices across most interstimulus intervals (Figure 8b), indicating a synergistic effect of RanBP9 and APP/PS1 genotypes on cooperative presynaptic efficacy. For long-term potentiation (LTP) measurements, we detected no differences in fEPSP slope among WT, APP/PS1, RanBP9+/−, and APP/PS1;RanBP9+/− slices at baseline (Figure 8c). However, after theta burst stimulation, we observed significant differences in fEPSP slope across genotypes for all time points (Figure 8c). Correction for multiple comparisons showed that APP/PS1 slices were significantly impaired in fEPSP slope compared with WT, RanBP9+/−, and APP/PS1;RanBP9+/− slices at every time point up to 1 h (Figure 8c). APP/PS1;RanBP9+/− slices exhibited significantly stronger fEPSP slope across all time points compared with WT and APP/PS1 slices (Figure 8c), indicating that RanBP9 reduction greatly enhances both the induction and maintenance of LTP. Similarly, RanBP9+/− slices exhibited significantly stronger LTP than WT slices up to 30 min and did not significantly differ from APP/PS1;RanBP9+/− slices (Figure 8c). Therefore, these results indicate that RanBP9 reduction not only rescues the deficits in synaptic plasticity associated with the APP/PS1 mice but also further potentiates synaptic plasticity.

Bottom Line: In this study, we found that endogenous RanBP9 positively regulates SSH1 levels and mediates Aβ-induced translocation of cofilin to mitochondria and induction of cofilin-actin pathology in cultured cells, primary neurons, and in vivo.Endogenous level of RanBP9 was also required for Aβ-induced collapse of growth cones in immature neurons (days in vitro 9 (DIV9)) and depletion of synaptic proteins in mature neurons (DIV21).Therefore, these results underscore the critical importance of endogenous RanBP9 not only in Aβ accumulation but also in mediating the neurotoxic actions of Aβ at the level of synaptic plasticity, mitochondria, and cofilin-actin pathology via control of the SSH1-cofilin pathway in vivo.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Medicine, USF Health Byrd Alzheimer's Institute, Tampa, FL, USA.

ABSTRACT
Molecular pathways underlying the neurotoxicity and production of amyloid β protein (Aβ) represent potentially promising therapeutic targets for Alzheimer's disease (AD). We recently found that overexpression of the scaffolding protein RanBP9 increases Aβ production in cell lines and in transgenic mice while promoting cofilin activation and mitochondrial dysfunction. Translocation of cofilin to mitochondria and induction of cofilin-actin pathology require the activation/dephosphorylation of cofilin by Slingshot homolog 1 (SSH1) and cysteine oxidation of cofilin. In this study, we found that endogenous RanBP9 positively regulates SSH1 levels and mediates Aβ-induced translocation of cofilin to mitochondria and induction of cofilin-actin pathology in cultured cells, primary neurons, and in vivo. Endogenous level of RanBP9 was also required for Aβ-induced collapse of growth cones in immature neurons (days in vitro 9 (DIV9)) and depletion of synaptic proteins in mature neurons (DIV21). In vivo, amyloid precursor protein (APP)/presenilin-1 (PS1) mice exhibited 3.5-fold increased RanBP9 levels, and RanBP9 reduction protected against cofilin-actin pathology, synaptic damage, gliosis, and Aβ accumulation associated with APP/PS1 mice. Brains slices derived from APP/PS1 mice showed significantly impaired long-term potentiation (LTP), and RanBP9 reduction significantly enhanced paired pulse facilitation and LTP, as well as partially rescued contextual memory deficits associated with APP/PS1 mice. Therefore, these results underscore the critical importance of endogenous RanBP9 not only in Aβ accumulation but also in mediating the neurotoxic actions of Aβ at the level of synaptic plasticity, mitochondria, and cofilin-actin pathology via control of the SSH1-cofilin pathway in vivo.

Show MeSH
Related in: MedlinePlus