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Zheng Z, Zhou H, Yang L, Zhang L, Guo M. Selective disruption of mTORC1 and mTORC2 in VTA astrocytes induces depression and anxiety-like behaviors in mice. Behav Brain Res 2024; 463:114888. [PMID: 38307148 DOI: 10.1016/j.bbr.2024.114888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 01/23/2024] [Accepted: 01/29/2024] [Indexed: 02/04/2024]
Abstract
Dysfunction of the mechanistic target of rapamycin (mTOR) signaling pathway is implicated in neuropsychiatric disorders including depression and anxiety. Most studies have been focusing on neurons, and the function of mTOR signaling pathway in astrocytes is less investigated. mTOR forms two distinct complexes, mTORC1 and mTORC2, with key scaffolding protein Raptor and Rictor, respectively. The ventral tegmental area (VTA), a vital component of the brain reward system, is enrolled in regulating both depression and anxiety. In the present study, we aimed to examine the regulation effect of VTA astrocytic mTOR signaling pathway on depression and anxiety. We specifically deleted Raptor or Rictor in VTA astrocytes in mice and performed a series of behavioral tests for depression and anxiety. Deletion of Raptor and Rictor both decreased the immobility time in the tail suspension test and the latency to eat in the novelty suppressed feeding test, and increased the horizontal activity and the movement time in locomotor activity. Deletion of Rictor decreased the number of total arm entries in the elevated plus-maze test and the vertical activity in locomotor activity. These data suggest that VTA astrocytic mTORC1 plays a role in regulating depression-related behaviors and mTORC2 is involved in both depression and anxiety-related behaviors. Our results indicate that VTA astrocytic mTOR signaling pathway might be new targets for the treatment of psychiatric disorders.
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Affiliation(s)
- Ziteng Zheng
- Department of Psychology, Binzhou Medical University Hospital, the First School of Clinical Medicine of Binzhou Medical University, Binzhou, Shandong 256603, China; Medical Research Center, Binzhou Medical University Hospital, the First School of Clinical Medicine of Binzhou Medical University, Binzhou, Shandong 256603, China
| | - Han Zhou
- Department of Psychology, Binzhou Medical University Hospital, the First School of Clinical Medicine of Binzhou Medical University, Binzhou, Shandong 256603, China; Medical Research Center, Binzhou Medical University Hospital, the First School of Clinical Medicine of Binzhou Medical University, Binzhou, Shandong 256603, China
| | - Lu Yang
- Department of Psychology, Binzhou Medical University Hospital, the First School of Clinical Medicine of Binzhou Medical University, Binzhou, Shandong 256603, China; Medical Research Center, Binzhou Medical University Hospital, the First School of Clinical Medicine of Binzhou Medical University, Binzhou, Shandong 256603, China
| | - Lanlan Zhang
- Department of Psychology, Binzhou Medical University Hospital, the First School of Clinical Medicine of Binzhou Medical University, Binzhou, Shandong 256603, China
| | - Ming Guo
- Department of Psychology, Binzhou Medical University Hospital, the First School of Clinical Medicine of Binzhou Medical University, Binzhou, Shandong 256603, China; Medical Research Center, Binzhou Medical University Hospital, the First School of Clinical Medicine of Binzhou Medical University, Binzhou, Shandong 256603, China.
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Kosillo P, Ahmed KM, Aisenberg EE, Karalis V, Roberts BM, Cragg SJ, Bateup HS. Dopamine neuron morphology and output are differentially controlled by mTORC1 and mTORC2. eLife 2022; 11:e75398. [PMID: 35881440 PMCID: PMC9328766 DOI: 10.7554/elife.75398] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 07/08/2022] [Indexed: 02/07/2023] Open
Abstract
The mTOR pathway is an essential regulator of cell growth and metabolism. Midbrain dopamine neurons are particularly sensitive to mTOR signaling status as activation or inhibition of mTOR alters their morphology and physiology. mTOR exists in two distinct multiprotein complexes termed mTORC1 and mTORC2. How each of these complexes affect dopamine neuron properties, and whether they have similar or distinct functions is unknown. Here, we investigated this in mice with dopamine neuron-specific deletion of Rptor or Rictor, which encode obligatory components of mTORC1 or mTORC2, respectively. We find that inhibition of mTORC1 strongly and broadly impacts dopamine neuron structure and function causing somatodendritic and axonal hypotrophy, increased intrinsic excitability, decreased dopamine production, and impaired dopamine release. In contrast, inhibition of mTORC2 has more subtle effects, with selective alterations to the output of ventral tegmental area dopamine neurons. Disruption of both mTOR complexes leads to pronounced deficits in dopamine release demonstrating the importance of balanced mTORC1 and mTORC2 signaling for dopaminergic function.
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Affiliation(s)
- Polina Kosillo
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
| | - Kamran M Ahmed
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
| | - Erin E Aisenberg
- Helen Wills Neuroscience Institute, University of California, BerkeleyBerkeleyUnited States
| | - Vasiliki Karalis
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
| | - Bradley M Roberts
- Department of Physiology, Physiology, Anatomy and Genetics, University of OxfordOxfordUnited Kingdom
| | - Stephanie J Cragg
- Department of Physiology, Physiology, Anatomy and Genetics, University of OxfordOxfordUnited Kingdom
| | - Helen S Bateup
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
- Helen Wills Neuroscience Institute, University of California, BerkeleyBerkeleyUnited States
- Chan Zuckerberg Biohub, San FranciscoSan FranciscoUnited States
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Al Khazal F, Kang S, Nelson Holte M, Choi DS, Singh R, Ortega-Sáenz P, López-Barneo J, Maher LJ. Unexpected obesity, rather than tumorigenesis, in a conditional mouse model of mitochondrial complex II deficiency. FASEB J 2020; 35:e21227. [PMID: 33247500 PMCID: PMC7861419 DOI: 10.1096/fj.202002100r] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 10/29/2020] [Accepted: 11/11/2020] [Indexed: 12/28/2022]
Abstract
Mutations in any of the genes encoding the four subunits of succinate dehydrogenase (SDH), a mitochondrial membrane‐bound enzyme complex that is involved in both the tricarboxylic acid cycle and the electron transport chain, can lead to a variety of disorders. Recognized conditions with such mutations include Leigh syndrome and hereditary tumors such as pheochromocytoma and paraganglioma (PPGL), renal cell carcinoma, and gastrointestinal stromal tumor. Tumors appear in SDH mutation carriers with dominant inheritance due to loss of heterozygosity in susceptible cells. Here, we describe a mouse model intended to reproduce hereditary PPGL through Cre‐mediated loss of SDHC in cells that express tyrosine hydroxylase (TH), a compartment where PPGL is known to originate. We report that while there is modest expansion of TH+ glomus cells in the carotid body upon SDHC loss, PPGL is not observed in such mice, even in the presence of a conditional dominant negative p53 protein and chronic hypoxia. Instead, we report an unexpected phenotype of nondiabetic obesity beginning at about 20 weeks of age. We hypothesize that this obesity is caused by TH+ cell loss or altered phenotype in key compartments of the central nervous system responsible for regulating feeding behavior, coupled with metabolic changes due to loss of peripheral catecholamine production.
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Affiliation(s)
- Fatimah Al Khazal
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine and Science, Rochester, MN, USA
| | - Seungwoo Kang
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN, USA
| | - Molly Nelson Holte
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine and Science, Rochester, MN, USA
| | - Doo-Sup Choi
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN, USA
| | - Ravinder Singh
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | - Patricia Ortega-Sáenz
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocio/CSIC/Universidad de Sevilla, Sevilla, Spain
| | - José López-Barneo
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocio/CSIC/Universidad de Sevilla, Sevilla, Spain
| | - L James Maher
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine and Science, Rochester, MN, USA
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Kaska S, Brunk R, Bali V, Kechner M, Mazei-Robison MS. Deletion of Rictor in catecholaminergic neurons alters locomotor activity and ingestive behavior. Neuropharmacology 2017; 117:158-170. [PMID: 28167137 DOI: 10.1016/j.neuropharm.2017.02.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 01/31/2017] [Accepted: 02/02/2017] [Indexed: 01/09/2023]
Abstract
While the etiology of depression is not fully understood, increasing evidence from animal models suggests a role for the ventral tegmental area (VTA) in pathogenesis. In this paper, we investigate the potential role of VTA mechanistic target of rapamycin 2 (TORC2) signaling in mediating susceptibility to chronic social defeat stress (CSDS), a well-established mouse model of depression. Utilizing genetic and viral knockout of Rictor (rapamycin-insensitive companion of target of rapamycin), a requisite component of TORC2, we demonstrate that decreasing Rictor-dependent TORC2 signaling in catecholaminergic neurons, or within the VTA specifically, does not alter susceptibility to CSDS. Opiate abuse and mood disorders are often comorbid, and previous data demonstrate a role for VTA TORC2 in mediating opiate reward. Thus, we also investigated its potential role in mediating changes in opiate reward following CSDS. Catecholaminergic deletion of Rictor increases water, sucrose, and morphine intake but not preference in a two-bottle choice assay in stress-naïve mice, and these effects are maintained after stress. VTA-specific knockout of Rictor increases water and sucrose intake after physical CSDS, but does not alter consummatory behavior in the absence of stress. These findings suggest a novel role for TORC2 in mediating stress-induced changes in consummatory behaviors that may contribute to some aspects of mood disorders.
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Affiliation(s)
- Sophia Kaska
- Dept. of Pharmacology and Toxicology, Michigan State University, East Lansing, MI 48824, United States
| | - Rebecca Brunk
- Neuroscience Program, Michigan State University, East Lansing, MI 48824, United States
| | - Vedrana Bali
- Dept. of Physiology, Michigan State University, East Lansing, MI 48824, United States
| | - Megan Kechner
- Neuroscience Program, Michigan State University, East Lansing, MI 48824, United States
| | - Michelle S Mazei-Robison
- Neuroscience Program, Michigan State University, East Lansing, MI 48824, United States; Dept. of Physiology, Michigan State University, East Lansing, MI 48824, United States.
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