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REDD1 is essential for stress-induced synaptic loss and depressive behavior.

Ota KT, Liu RJ, Voleti B, Maldonado-Aviles JG, Duric V, Iwata M, Dutheil S, Duman C, Boikess S, Lewis DA, Stockmeier CA, DiLeone RJ, Rex C, Aghajanian GK, Duman RS - Nat. Med. (2014)

Bottom Line: Major depressive disorder (MDD) affects up to 17% of the population, causing profound personal suffering and economic loss.Here, we show that stress increases levels of REDD1 (regulated in development and DNA damage responses-1), an inhibitor of mTORC1 (mammalian target of rapamycin complex-1; ref. 10), in rat prefrontal cortex (PFC).This is concurrent with a decrease in phosphorylation of signaling targets of mTORC1, which is implicated in protein synthesis-dependent synaptic plasticity.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Molecular Psychiatry, Center for Genes and Behavior, Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut, USA.

ABSTRACT
Major depressive disorder (MDD) affects up to 17% of the population, causing profound personal suffering and economic loss. Clinical and preclinical studies have revealed that prolonged stress and MDD are associated with neuronal atrophy of cortical and limbic brain regions, but the molecular mechanisms underlying these morphological alterations have not yet been identified. Here, we show that stress increases levels of REDD1 (regulated in development and DNA damage responses-1), an inhibitor of mTORC1 (mammalian target of rapamycin complex-1; ref. 10), in rat prefrontal cortex (PFC). This is concurrent with a decrease in phosphorylation of signaling targets of mTORC1, which is implicated in protein synthesis-dependent synaptic plasticity. We also found that REDD1 levels are increased in the postmortem PFC of human subjects with MDD relative to matched controls. Mutant mice with a deletion of the gene encoding REDD1 are resilient to the behavioral, synaptic and mTORC1 signaling deficits caused by chronic unpredictable stress, whereas viral-mediated overexpression of REDD1 in rat PFC is sufficient to cause anxiety- and depressive-like behaviors and neuronal atrophy. Taken together, these postmortem and preclinical findings identify REDD1 as a critical mediator of the atrophy of neurons and depressive behavior caused by chronic stress exposure.

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REDD1 knock out mice are resilient to CUS-induced alterations in the PFC(a) REDD1 KO mice and their wild-type littermates received 21 d of CUS or regular handling (Ctrl), then were behaviorally tested. After testing, mice continued to receive CUS or regular handling for 7 d, then sacrificed 4 h after the final stressor. (b) Ratio of sucrose to water consumption (± SEM) over a 1 h test is depicted for WT Ctrl (n=13), WT CUS (n=14), KO Ctrl (n=16), and KO CUS (n=17) groups. ANOVA revealed a significant effect of genotype [F(1,56) = 4.47; p < 0.05], stress [F(1,56) = 5.809; p < 0.03], and genotype x stress interaction [F(1,56) = 4.157; p < 0.05]. (c) Phospho-protein levels in PFC were analyzed in WT Ctrl (n=13), WT CUS (n=14), KO Ctrl (n=16), and KO CUS (n=17) groups. Results are the mean ± SEM fold change. Phospho-protein levels were normalized to total protein levels and representative blots are displayed. ANOVA for phospho-S6K revealed a significant genotype x stress interaction [F(1, 56) = 7.632, p < 0.01] and a main effect of genotype [F(1, 56) = 12.08, p < 0.01], but no main effect of stress. ANOVA for phospho-4EBP1 showed a significant genotype x stress interaction [F(1, 56) = 4.939, p < 0.05] and a main effect of genotype [F(1, 56) = 4.077, p < 0.05], but no main effect of stress. (d) Left. Sample whole-cell voltage-clamp traces of serotonin (5-HT) and hypocretin (Hcrt)-induced EPSCs in layer V pyramidal cells. Scale is depicted on the lower right. Right. Mean ± SEM frequency of 5-HT and Hcrt-induced EPSCs from WT Ctrl (5-HT n=16; Hcrt n=13), WT CUS (5-HT n=16; Hcrt n=16), KO Ctrl (5-HT n=16; Hcrt n=15), and KO CUS (5-HT n=16; Hcrt n=16) groups is depicted. ANOVA for 5-HT-induced EPSCs in layer V pyramidal neurons of the mPFC showed a significant main effect of stress [F(1,60) = 6.131, p < 0.05] and a trend for a main effect of genotype [F(1,60) = 3.124, p < 0.10], but no stress x genotype interaction. ANOVA of Hcrt-induced EPSCs revealed a significant main effect of stress [F(1,56)=7.809, p < 0.01] and a significant stress x genotype interaction [F(1,56)=4.046, p < 0.05], but no main effect of genotype. (e) Left. Representative images are shown of high magnification Z-stack projections of segments of the layer V pyramidal cell apical tuft dendrites (scale: 5 μm). Right. Mean ± SEM of spine density from WT Ctrl (n=30), WT CUS (n=41), KO Ctrl (n=27), and KO CUS (n=23) groups is depicted. ANOVA for spine density in the recorded cells revealed a significant main effect of stress [F(1,117) = 4.487, p < 0.05] and genotype [F(1,117) = 4.183, p < 0.05], but no stress x genotype interaction (*) p < 0.05 relative to WT Ctrl mice. (#) p < 0.10 relative to WT Ctrl mice.
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Figure 3: REDD1 knock out mice are resilient to CUS-induced alterations in the PFC(a) REDD1 KO mice and their wild-type littermates received 21 d of CUS or regular handling (Ctrl), then were behaviorally tested. After testing, mice continued to receive CUS or regular handling for 7 d, then sacrificed 4 h after the final stressor. (b) Ratio of sucrose to water consumption (± SEM) over a 1 h test is depicted for WT Ctrl (n=13), WT CUS (n=14), KO Ctrl (n=16), and KO CUS (n=17) groups. ANOVA revealed a significant effect of genotype [F(1,56) = 4.47; p < 0.05], stress [F(1,56) = 5.809; p < 0.03], and genotype x stress interaction [F(1,56) = 4.157; p < 0.05]. (c) Phospho-protein levels in PFC were analyzed in WT Ctrl (n=13), WT CUS (n=14), KO Ctrl (n=16), and KO CUS (n=17) groups. Results are the mean ± SEM fold change. Phospho-protein levels were normalized to total protein levels and representative blots are displayed. ANOVA for phospho-S6K revealed a significant genotype x stress interaction [F(1, 56) = 7.632, p < 0.01] and a main effect of genotype [F(1, 56) = 12.08, p < 0.01], but no main effect of stress. ANOVA for phospho-4EBP1 showed a significant genotype x stress interaction [F(1, 56) = 4.939, p < 0.05] and a main effect of genotype [F(1, 56) = 4.077, p < 0.05], but no main effect of stress. (d) Left. Sample whole-cell voltage-clamp traces of serotonin (5-HT) and hypocretin (Hcrt)-induced EPSCs in layer V pyramidal cells. Scale is depicted on the lower right. Right. Mean ± SEM frequency of 5-HT and Hcrt-induced EPSCs from WT Ctrl (5-HT n=16; Hcrt n=13), WT CUS (5-HT n=16; Hcrt n=16), KO Ctrl (5-HT n=16; Hcrt n=15), and KO CUS (5-HT n=16; Hcrt n=16) groups is depicted. ANOVA for 5-HT-induced EPSCs in layer V pyramidal neurons of the mPFC showed a significant main effect of stress [F(1,60) = 6.131, p < 0.05] and a trend for a main effect of genotype [F(1,60) = 3.124, p < 0.10], but no stress x genotype interaction. ANOVA of Hcrt-induced EPSCs revealed a significant main effect of stress [F(1,56)=7.809, p < 0.01] and a significant stress x genotype interaction [F(1,56)=4.046, p < 0.05], but no main effect of genotype. (e) Left. Representative images are shown of high magnification Z-stack projections of segments of the layer V pyramidal cell apical tuft dendrites (scale: 5 μm). Right. Mean ± SEM of spine density from WT Ctrl (n=30), WT CUS (n=41), KO Ctrl (n=27), and KO CUS (n=23) groups is depicted. ANOVA for spine density in the recorded cells revealed a significant main effect of stress [F(1,117) = 4.487, p < 0.05] and genotype [F(1,117) = 4.183, p < 0.05], but no stress x genotype interaction (*) p < 0.05 relative to WT Ctrl mice. (#) p < 0.10 relative to WT Ctrl mice.

Mentions: To directly test the role of REDD1 in the effects of chronic stress, we used REDD1 constitutive knock out (KO) mice. REDD1 deletion in PFC was confirmed (p < 0.0001) (Supplementary Fig. 3a). KO mice did not display any apparent physical or behavioral abnormalities despite a previous report suggesting a role for REDD1 in embryonic development (19) (Supplementary Fig. 3b–d). This lack of baseline behavioral differences was not surprising given the low level of REDD1 expression in brain (20). However, CUS exposure (21 d), which causes anhedonic behavior (i.e., decreased sucrose consumption) in WT mice, had no effect in REDD1 KO mice, indicating resilience to CUS (Fig. 3a-b). Sucrose consumption was significantly decreased in the WT CUS group relative to all other groups (p < 0.01). CUS also decreased phospho-S6K and phospho-4EBP levels in the PFC of WT, but not REDD1 KO mice (Fig. 3c). There was a non-significant trend for decreased levels of phospho-mTOR in the WT CUS group.


REDD1 is essential for stress-induced synaptic loss and depressive behavior.

Ota KT, Liu RJ, Voleti B, Maldonado-Aviles JG, Duric V, Iwata M, Dutheil S, Duman C, Boikess S, Lewis DA, Stockmeier CA, DiLeone RJ, Rex C, Aghajanian GK, Duman RS - Nat. Med. (2014)

REDD1 knock out mice are resilient to CUS-induced alterations in the PFC(a) REDD1 KO mice and their wild-type littermates received 21 d of CUS or regular handling (Ctrl), then were behaviorally tested. After testing, mice continued to receive CUS or regular handling for 7 d, then sacrificed 4 h after the final stressor. (b) Ratio of sucrose to water consumption (± SEM) over a 1 h test is depicted for WT Ctrl (n=13), WT CUS (n=14), KO Ctrl (n=16), and KO CUS (n=17) groups. ANOVA revealed a significant effect of genotype [F(1,56) = 4.47; p < 0.05], stress [F(1,56) = 5.809; p < 0.03], and genotype x stress interaction [F(1,56) = 4.157; p < 0.05]. (c) Phospho-protein levels in PFC were analyzed in WT Ctrl (n=13), WT CUS (n=14), KO Ctrl (n=16), and KO CUS (n=17) groups. Results are the mean ± SEM fold change. Phospho-protein levels were normalized to total protein levels and representative blots are displayed. ANOVA for phospho-S6K revealed a significant genotype x stress interaction [F(1, 56) = 7.632, p < 0.01] and a main effect of genotype [F(1, 56) = 12.08, p < 0.01], but no main effect of stress. ANOVA for phospho-4EBP1 showed a significant genotype x stress interaction [F(1, 56) = 4.939, p < 0.05] and a main effect of genotype [F(1, 56) = 4.077, p < 0.05], but no main effect of stress. (d) Left. Sample whole-cell voltage-clamp traces of serotonin (5-HT) and hypocretin (Hcrt)-induced EPSCs in layer V pyramidal cells. Scale is depicted on the lower right. Right. Mean ± SEM frequency of 5-HT and Hcrt-induced EPSCs from WT Ctrl (5-HT n=16; Hcrt n=13), WT CUS (5-HT n=16; Hcrt n=16), KO Ctrl (5-HT n=16; Hcrt n=15), and KO CUS (5-HT n=16; Hcrt n=16) groups is depicted. ANOVA for 5-HT-induced EPSCs in layer V pyramidal neurons of the mPFC showed a significant main effect of stress [F(1,60) = 6.131, p < 0.05] and a trend for a main effect of genotype [F(1,60) = 3.124, p < 0.10], but no stress x genotype interaction. ANOVA of Hcrt-induced EPSCs revealed a significant main effect of stress [F(1,56)=7.809, p < 0.01] and a significant stress x genotype interaction [F(1,56)=4.046, p < 0.05], but no main effect of genotype. (e) Left. Representative images are shown of high magnification Z-stack projections of segments of the layer V pyramidal cell apical tuft dendrites (scale: 5 μm). Right. Mean ± SEM of spine density from WT Ctrl (n=30), WT CUS (n=41), KO Ctrl (n=27), and KO CUS (n=23) groups is depicted. ANOVA for spine density in the recorded cells revealed a significant main effect of stress [F(1,117) = 4.487, p < 0.05] and genotype [F(1,117) = 4.183, p < 0.05], but no stress x genotype interaction (*) p < 0.05 relative to WT Ctrl mice. (#) p < 0.10 relative to WT Ctrl mice.
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Figure 3: REDD1 knock out mice are resilient to CUS-induced alterations in the PFC(a) REDD1 KO mice and their wild-type littermates received 21 d of CUS or regular handling (Ctrl), then were behaviorally tested. After testing, mice continued to receive CUS or regular handling for 7 d, then sacrificed 4 h after the final stressor. (b) Ratio of sucrose to water consumption (± SEM) over a 1 h test is depicted for WT Ctrl (n=13), WT CUS (n=14), KO Ctrl (n=16), and KO CUS (n=17) groups. ANOVA revealed a significant effect of genotype [F(1,56) = 4.47; p < 0.05], stress [F(1,56) = 5.809; p < 0.03], and genotype x stress interaction [F(1,56) = 4.157; p < 0.05]. (c) Phospho-protein levels in PFC were analyzed in WT Ctrl (n=13), WT CUS (n=14), KO Ctrl (n=16), and KO CUS (n=17) groups. Results are the mean ± SEM fold change. Phospho-protein levels were normalized to total protein levels and representative blots are displayed. ANOVA for phospho-S6K revealed a significant genotype x stress interaction [F(1, 56) = 7.632, p < 0.01] and a main effect of genotype [F(1, 56) = 12.08, p < 0.01], but no main effect of stress. ANOVA for phospho-4EBP1 showed a significant genotype x stress interaction [F(1, 56) = 4.939, p < 0.05] and a main effect of genotype [F(1, 56) = 4.077, p < 0.05], but no main effect of stress. (d) Left. Sample whole-cell voltage-clamp traces of serotonin (5-HT) and hypocretin (Hcrt)-induced EPSCs in layer V pyramidal cells. Scale is depicted on the lower right. Right. Mean ± SEM frequency of 5-HT and Hcrt-induced EPSCs from WT Ctrl (5-HT n=16; Hcrt n=13), WT CUS (5-HT n=16; Hcrt n=16), KO Ctrl (5-HT n=16; Hcrt n=15), and KO CUS (5-HT n=16; Hcrt n=16) groups is depicted. ANOVA for 5-HT-induced EPSCs in layer V pyramidal neurons of the mPFC showed a significant main effect of stress [F(1,60) = 6.131, p < 0.05] and a trend for a main effect of genotype [F(1,60) = 3.124, p < 0.10], but no stress x genotype interaction. ANOVA of Hcrt-induced EPSCs revealed a significant main effect of stress [F(1,56)=7.809, p < 0.01] and a significant stress x genotype interaction [F(1,56)=4.046, p < 0.05], but no main effect of genotype. (e) Left. Representative images are shown of high magnification Z-stack projections of segments of the layer V pyramidal cell apical tuft dendrites (scale: 5 μm). Right. Mean ± SEM of spine density from WT Ctrl (n=30), WT CUS (n=41), KO Ctrl (n=27), and KO CUS (n=23) groups is depicted. ANOVA for spine density in the recorded cells revealed a significant main effect of stress [F(1,117) = 4.487, p < 0.05] and genotype [F(1,117) = 4.183, p < 0.05], but no stress x genotype interaction (*) p < 0.05 relative to WT Ctrl mice. (#) p < 0.10 relative to WT Ctrl mice.
Mentions: To directly test the role of REDD1 in the effects of chronic stress, we used REDD1 constitutive knock out (KO) mice. REDD1 deletion in PFC was confirmed (p < 0.0001) (Supplementary Fig. 3a). KO mice did not display any apparent physical or behavioral abnormalities despite a previous report suggesting a role for REDD1 in embryonic development (19) (Supplementary Fig. 3b–d). This lack of baseline behavioral differences was not surprising given the low level of REDD1 expression in brain (20). However, CUS exposure (21 d), which causes anhedonic behavior (i.e., decreased sucrose consumption) in WT mice, had no effect in REDD1 KO mice, indicating resilience to CUS (Fig. 3a-b). Sucrose consumption was significantly decreased in the WT CUS group relative to all other groups (p < 0.01). CUS also decreased phospho-S6K and phospho-4EBP levels in the PFC of WT, but not REDD1 KO mice (Fig. 3c). There was a non-significant trend for decreased levels of phospho-mTOR in the WT CUS group.

Bottom Line: Major depressive disorder (MDD) affects up to 17% of the population, causing profound personal suffering and economic loss.Here, we show that stress increases levels of REDD1 (regulated in development and DNA damage responses-1), an inhibitor of mTORC1 (mammalian target of rapamycin complex-1; ref. 10), in rat prefrontal cortex (PFC).This is concurrent with a decrease in phosphorylation of signaling targets of mTORC1, which is implicated in protein synthesis-dependent synaptic plasticity.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Molecular Psychiatry, Center for Genes and Behavior, Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut, USA.

ABSTRACT
Major depressive disorder (MDD) affects up to 17% of the population, causing profound personal suffering and economic loss. Clinical and preclinical studies have revealed that prolonged stress and MDD are associated with neuronal atrophy of cortical and limbic brain regions, but the molecular mechanisms underlying these morphological alterations have not yet been identified. Here, we show that stress increases levels of REDD1 (regulated in development and DNA damage responses-1), an inhibitor of mTORC1 (mammalian target of rapamycin complex-1; ref. 10), in rat prefrontal cortex (PFC). This is concurrent with a decrease in phosphorylation of signaling targets of mTORC1, which is implicated in protein synthesis-dependent synaptic plasticity. We also found that REDD1 levels are increased in the postmortem PFC of human subjects with MDD relative to matched controls. Mutant mice with a deletion of the gene encoding REDD1 are resilient to the behavioral, synaptic and mTORC1 signaling deficits caused by chronic unpredictable stress, whereas viral-mediated overexpression of REDD1 in rat PFC is sufficient to cause anxiety- and depressive-like behaviors and neuronal atrophy. Taken together, these postmortem and preclinical findings identify REDD1 as a critical mediator of the atrophy of neurons and depressive behavior caused by chronic stress exposure.

Show MeSH
Related in: MedlinePlus