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Hu Z, Yuan Y, Tong Z, Liao M, Yuan S, Wu W, Tang Y, Wang Y, Tang C, Liu W. Aerobic Exercise Facilitates the Nuclear Translocation of SREBP2 by Activating AKT/SEC24D to Contribute Cholesterol Homeostasis for Improving Cognition in APP/PS1 Mice. Int J Mol Sci 2023; 24:12847. [PMID: 37629027 PMCID: PMC10454400 DOI: 10.3390/ijms241612847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 08/06/2023] [Accepted: 08/14/2023] [Indexed: 08/27/2023] Open
Abstract
Impaired cholesterol synthesizing ability is considered a risk factor for the development of Alzheimer's disease (AD), as evidenced by reduced levels of key proteases in the brain that mediate cholesterol synthesis; however, cholesterol deposition has been found in neurons in tangles in the brains of AD patients. Although it has been shown that statins, which inhibit cholesterol synthesis, reduce the incidence of AD, this seems paradoxical for AD patients whose cholesterol synthesizing capacity is already impaired. In this study, we aimed to investigate the effects of aerobic exercise on cholesterol metabolism in the brains of APP/PS1 mice and to reveal the mechanisms by which aerobic exercise improves cognitive function in APP/PS1 mice. Our study demonstrates that the reduction of SEC24D protein, a component of coat protein complex II (COPII), is a key factor in the reduction of cholesterol synthesis in the brain of APP/PS1 mice. 12 weeks of aerobic exercise was able to promote the recovery of SEC24D protein levels in the brain through activation of protein kinase B (AKT), which in turn promoted the expression of mem-brane-bound sterol regulatory element-binding protein 2 (SREBP2) nuclear translocation and the expression of key proteases mediating cholesterol synthesis. Simultaneous aerobic exercise restored cholesterol transport capacity in the brain of APP/PS1 mice with the ability to efflux excess cholesterol from neurons and reduced neuronal lipid rafts, thereby reducing cleavage of the APP amyloid pathway. Our study emphasizes the potential of restoring intracerebral cholesterol homeostasis as a therapeutic strategy to alleviate cognitive impairment in AD patients.
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Affiliation(s)
- Zelin Hu
- Hunan Provincial Key Laboratory of Physical Fitness and Sports Rehabilitation, Hunan Normal University, Changsha 410012, China
| | - Yangqi Yuan
- Hunan Provincial Key Laboratory of Physical Fitness and Sports Rehabilitation, Hunan Normal University, Changsha 410012, China
| | - Zhen Tong
- Hunan Provincial Key Laboratory of Physical Fitness and Sports Rehabilitation, Hunan Normal University, Changsha 410012, China
| | - Meiqing Liao
- Hunan Provincial Key Laboratory of Physical Fitness and Sports Rehabilitation, Hunan Normal University, Changsha 410012, China
| | - Shunling Yuan
- Hunan Provincial Key Laboratory of Physical Fitness and Sports Rehabilitation, Hunan Normal University, Changsha 410012, China
| | - Weijia Wu
- Hunan Provincial Key Laboratory of Physical Fitness and Sports Rehabilitation, Hunan Normal University, Changsha 410012, China
| | - Yingzhe Tang
- Hunan Provincial Key Laboratory of Physical Fitness and Sports Rehabilitation, Hunan Normal University, Changsha 410012, China
| | - Yirong Wang
- Hunan Provincial Key Laboratory of Physical Fitness and Sports Rehabilitation, Hunan Normal University, Changsha 410012, China
| | - Changfa Tang
- Hunan Provincial Key Laboratory of Physical Fitness and Sports Rehabilitation, Hunan Normal University, Changsha 410012, China
| | - Wenfeng Liu
- Hunan Provincial Key Laboratory of Physical Fitness and Sports Rehabilitation, Hunan Normal University, Changsha 410012, China
- Key Laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, Hunan Normal University, Changsha 410081, China
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Chen L, Ma MY, Sun M, Jiang LY, Zhao XT, Fang XX, Man Lam S, Shui GH, Luo J, Shi XJ, Song BL. Endogenous sterol intermediates of the mevalonate pathway regulate HMGCR degradation and SREBP-2 processing. J Lipid Res 2019; 60:1765-1775. [PMID: 31455613 DOI: 10.1194/jlr.ra119000201] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 08/21/2019] [Indexed: 11/20/2022] Open
Abstract
Sterol-regulated HMG-CoA reductase (HMGCR) degradation and SREBP-2 cleavage are two major feedback regulatory mechanisms governing cholesterol biosynthesis. Reportedly, lanosterol selectively stimulates HMGCR degradation, and cholesterol is a specific regulator of SREBP-2 cleavage. However, it is unclear whether other endogenously generated sterols regulate these events. Here, we investigated the sterol intermediates from the mevalonate pathway of cholesterol biosynthesis using a CRISPR/Cas9-mediated genetic engineering approach. With a constructed HeLa cell line expressing the mevalonate transporter, we individually deleted genes encoding major enzymes in the mevalonate pathway, used lipidomics to measure sterol intermediates, and examined HMGCR and SREBP-2 statuses. We found that the C4-dimethylated sterol intermediates, including lanosterol, 24,25-dihydrolanosterol, follicular fluid meiosis activating sterol, testis meiosis activating sterol, and dihydro-testis meiosis activating sterol, were significantly upregulated upon mevalonate loading. These intermediates augmented both degradation of HMGCR and inhibition of SREBP-2 cleavage. The accumulated lanosterol induced rapid degradation of HMGCR, but did not inhibit SREBP-2 cleavage. The newly synthesized cholesterol from the mevalonate pathway is dispensable for inhibiting SREBP-2 cleavage. Together, these results suggest that lanosterol is a bona fide endogenous regulator that specifically promotes HMGCR degradation, and that other C4-dimethylated sterol intermediates may regulate both HMGCR degradation and SREBP-2 cleavage.
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Affiliation(s)
- Liang Chen
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Mei-Yan Ma
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Ming Sun
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Lu-Yi Jiang
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Xue-Tong Zhao
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Xian-Xiu Fang
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Sin Man Lam
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology , Chinese Academy of Sciences, Beijing 100101, China
| | - Guang-Hou Shui
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology , Chinese Academy of Sciences, Beijing 100101, China
| | - Jie Luo
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Xiong-Jie Shi
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Bao-Liang Song
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan 430072, China
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Abstract
Background Metformin, as the first-line treatment anti-diabetic drug, represents increasing evidence of a potential efficacy in improving dyslipidemia. However, the exact molecular mechanism(s) by which metformin influences lipid metabolism remains incompletely understood. Methods The HepG2 cells were treated with metformin and the AMP-activated protein kinase (AMPK) inhibitor compound C or a dominant-negative form of AMPK plasmid. ELISA assay was employed to measure AMPK activity, and cellular cholesterol content was determined by enzymatic colorimetric method. RT-PCR and western blotting were used to detect SREBP-2 mRNA levels and its target protein levels. Results We found that metformin significantly stimulated AMPK activity and decreased intracellular total cholesterol contents in HepG2 cells. Metformin reduced the sterol regulatory element-binding protein-2 (SREBP-2) and its downstream target proteins and increased low-density lipoprotein receptor (LDLR) levels. Conclusion Our preliminary results demonstrate that metformin as a first-line and initial medication suppresses the synthesis of SREBP-2 and upregulates LDLR, and consequently decreases cholesterol production via activation of AMPK, at least partly. These findings suggest a therapeutic target and potential beneficial effects of metformin on the prevention of dyslipidemia or related diseases.
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Affiliation(s)
- Fengxia Zhang
- Department of Neurology, Affiliated Hospital of Shandong Traditional Chinese Medicine University, Jinan 250011, China
| | - Wenxiu Sun
- Department of Pharmacy, Taishan Vocational College of Nursing, Taian 271000, China
| | - Jianbo Chen
- Department of Endocrinology, Shandong Rongjun General Hospital, Jinan 250013, China,
| | - Lusheng Jiang
- Department of Endocrinology, Shandong Rongjun General Hospital, Jinan 250013, China,
| | - Ping Yang
- Department of Endocrinology, Shandong Rongjun General Hospital, Jinan 250013, China,
| | - Yufang Huang
- Department of Endocrinology, Shandong Rongjun General Hospital, Jinan 250013, China,
| | - Aihua Gong
- Department of Endocrinology, Shandong Rongjun General Hospital, Jinan 250013, China,
| | - Shudong Liu
- Department of Endocrinology, Shandong Rongjun General Hospital, Jinan 250013, China,
| | - Shizhan Ma
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital Affiliated to Shandong University, Jinan 250021, China,
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Mohamed A, Viveiros A, Williams K, Posse de Chaves E. Aβ inhibits SREBP-2 activation through Akt inhibition. J Lipid Res 2017; 59:1-13. [PMID: 29122977 PMCID: PMC5748492 DOI: 10.1194/jlr.m076703] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 10/21/2017] [Indexed: 12/20/2022] Open
Abstract
We previously demonstrated that oligomeric amyloid β42 (oAβ42) inhibits the mevalonate pathway impairing cholesterol synthesis and protein prenylation. Enzymes of the mevalonate pathway are regulated by the transcription factor SREBP-2. Here, we show that in several neuronal types challenged with oAβ42, SREBP-2 activation is reduced. Moreover, SREBP-2 activation is also decreased in the brain cortex of the Alzheimer's disease (AD) mouse model, TgCRND8, suggesting that SREBP-2 may be affected in vivo early in the disease. We demonstrate that oAβ42 does not affect enzymatic cleavage of SREBP-2 per se, but may impair SREBP-2 transport from the endoplasmic reticulum (ER) to the Golgi. Trafficking of SREBP-2 from the ER to the Golgi requires protein kinase B (Akt) activation. oAβ42 significantly reduces Akt phosphorylation and this decrease is responsible for the decline in SREBP-2 activation. Overexpression of constitutively active Akt prevents the effect of oAβ42 on SREBP-2 and the downstream inhibition of cholesterol synthesis and protein prenylation. Our work provides a novel mechanistic link between Aβ and the mevalonate pathway, which will impact the views on issues related to cholesterol, isoprenoids, and statins in AD. We also identify SREBP-2 as an indirect target of Akt in neurons, which may play a role in the cross-talk between AD and diabetes.
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Affiliation(s)
- Amany Mohamed
- Department of Pharmacology and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Anissa Viveiros
- Department of Pharmacology and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Kathleen Williams
- Department of Pharmacology and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Elena Posse de Chaves
- Department of Pharmacology and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
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Miyata M, Hata T, Yamazoe Y, Yoshinari K. SREBP-2 negatively regulates FXR-dependent transcription of FGF19 in human intestinal cells. Biochem Biophys Res Commun 2013; 443:477-82. [PMID: 24321096 DOI: 10.1016/j.bbrc.2013.11.126] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Accepted: 11/27/2013] [Indexed: 01/19/2023]
Abstract
Sterol regulatory element-binding protein-2 (SREBP-2) is a basic helix-loop-helix-leucine zipper transcription factor that positively regulates transcription of target genes involved in cholesterol metabolism. In the present study, we have investigated a possible involvement of SREBP-2 in human intestinal expression of fibroblast growth factor (FGF)19, which is an endocrine hormone involved in the regulation of lipid and glucose metabolism. Overexpression of constitutively active SREBP-2 decreased FGF19 mRNA levels in human colon-derived LS174T cells. In reporter assays, active SREBP-2 overexpression suppressed GW4064/FXR-mediated increase in reporter activities in regions containing the IR-1 motif (+848 to +5200) in the FGF19 gene. The suppressive effect disappeared in reporter activities in the region containing the IR-1 motif when the mutation was introduced into the IR-1 motif. In electrophoretic mobility shift assays, binding of the FXR/retinoid X receptor α heterodimer to the IR-1 motif was attenuated by adding active SREBP-2, but SREBP-2 binding to the IR-1 motif was not observed. In chromatin immunoprecipitation assays, specific binding of FXR to the IR-1-containing region of the FGF19 gene (+3214 to +3404) was increased in LS174T cells by treatment with cholesterol and 25-hydroxycholesterol. Specific binding of SREBP-2 to FXR was observed in glutathione-S-transferase (GST) pull-down assays. These results suggest that SREBP-2 negatively regulates the FXR-mediated transcriptional activation of the FGF19 gene in human intestinal cells.
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Affiliation(s)
- Masaaki Miyata
- Division of Drug Metabolism and Molecular Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3, Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan; Department of Food Science and Technology, National Fisheries University, 2-7-1, Nagatahonmatch, Shimonoseki 759-6595, Japan.
| | - Tatsuya Hata
- Division of Drug Metabolism and Molecular Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3, Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan
| | - Yasushi Yamazoe
- Division of Drug Metabolism and Molecular Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3, Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan
| | - Kouichi Yoshinari
- Division of Drug Metabolism and Molecular Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3, Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan
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Watanabe K, Sakurai K, Tsuchiya Y, Yamazoe Y, Yoshinari K. Dual roles of nuclear receptor liver X receptor α (LXRα) in the CYP3A4 expression in human hepatocytes as a positive and negative regulator. Biochem Pharmacol 2013; 86:428-36. [PMID: 23732298 DOI: 10.1016/j.bcp.2013.05.016] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 05/22/2013] [Accepted: 05/22/2013] [Indexed: 12/11/2022]
Abstract
CYP3A4 is a major drug-metabolizing enzyme in humans, whose expression levels show large inter-individual variations and are associated with several factors such as genetic polymorphism, physiological and disease status, diet and xenobiotic exposure. Nuclear receptor pregnane X receptor (PXR) is a key transcription factor for the xenobiotic-mediated transcription of CYP3A4. In this study, we have investigated a possible involvement of liver X receptor α (LXRα), a critical regulator of cholesterol homeostasis, in the hepatic CYP3A4 expression since several recent reports suggest the involvement of CYP3A enzymes in the cholesterol metabolism in humans and mice. Reporter assays using wild-type and mutated CYP3A4 luciferase reporter plasmids and electrophoretic mobility shift assays revealed that LXRα up-regulated CYP3A4 through the known DNA elements critical for the PXR-dependent CYP3A4 transcription, suggesting LXRα as a positive regulator for the CYP3A4 expression and a crosstalk between PXR and LXRα in the expression. In fact, reporter assays showed that LXRα activation attenuated the PXR-dependent CYP3A4 transcription. Moreover, a PXR agonist treatment-dependent increase in CYP3A4 mRNA levels was suppressed by co-treatment with an LXRα agonist in human primary hepatocytes and HepaRG cells. The suppression was not observed when LXRα expression was knocked-down in HepaRG cells. In conclusion, the present results suggest that sterol-sensitive LXRα positively regulates the basal expression of CYP3A4 but suppresses the xenobiotic/PXR-dependent CYP3A4 expression in human hepatocytes. Therefore, nutritional, physiological and disease conditions affecting LXRα might be one of the determinants for the basal and xenobiotic-responsive expression of CYP3A4 in human livers.
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Affiliation(s)
- Keisuke Watanabe
- Division of Drug Metabolism and Molecular Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, Japan
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Hashimoto M, Kobayashi K, Watanabe M, Kazuki Y, Takehara S, Inaba A, Nitta SI, Senda N, Oshimura M, Chiba K. Knockout of mouse Cyp3a gene enhances synthesis of cholesterol and bile acid in the liver. J Lipid Res 2013; 54:2060-2068. [PMID: 23709690 DOI: 10.1194/jlr.m033464] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Here, we studied the effects of cytochrome P450 (CYP)3A deficiency on the mRNA expression of genes encoding regulators of hepatic cholesterol levels using Cyp3a-knockout (Cyp3a(-/-)) mice. The mRNA expression levels of genes encoding enzymes involved in cholesterol biosynthesis in the livers of Cyp3a(-/-) mice were higher than those of wild-type (WT) mice. Nuclear levels of sterol regulatory element-binding protein-2 (SREBP-2), which enhances cholesterol biosynthesis, were also higher in the livers of Cyp3a(-/-) mice. Binding of SREBP-2 to the Hmgcs1 gene promoter was more abundant in the livers of Cyp3a(-/-) mice. These results suggest that deficiency of CYP3A enzymes enhances transcription of genes encoding enzymes involved in cholesterol biosynthesis via activation of SREBP-2. On the other hand, hepatic cholesterol levels in Cyp3a(-/-) mice were 20% lower than those in WT mice. The mRNA expression levels of genes encoding enzymes involved in bile acid synthesis, plasma levels of 7α-hydroxy-4-cholesten-3-one and hepatic levels of total bile acid were significantly higher in Cyp3a(-/-) mice than in WT mice. These findings suggest that reduction of hepatic total cholesterol in Cyp3a(-/-) mice would be the consequence of enhanced bile acid synthesis. Therefore, CYP3A enzymes appear to play roles in the synthesis of cholesterol and bile acid in vivo.
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Affiliation(s)
- Mari Hashimoto
- Laboratory of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 260-8675, Japan
| | - Kaoru Kobayashi
- Laboratory of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 260-8675, Japan
| | - Mio Watanabe
- Laboratory of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 260-8675, Japan
| | - Yasuhiro Kazuki
- Department of Biomedical Science, Institute of Regenerative Medicine and Biofunction, Graduate School of Medical Science, Tottori University, Tottori 683-8503, Japan; Chromosome Engineering Research Center (CERC), Tottori University, Tottori 683-8503, Japan
| | - Shoko Takehara
- Chromosome Engineering Research Center (CERC), Tottori University, Tottori 683-8503, Japan
| | - Asumi Inaba
- Laboratory of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 260-8675, Japan
| | - Shin-Ichiro Nitta
- Laboratory of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 260-8675, Japan; Mitsubishi Chemical Medience Corporation, Ibaraki 305-0047, Japan
| | - Naoto Senda
- Mitsubishi Chemical Medience Corporation, Ibaraki 305-0047, Japan
| | - Mitsuo Oshimura
- Department of Biomedical Science, Institute of Regenerative Medicine and Biofunction, Graduate School of Medical Science, Tottori University, Tottori 683-8503, Japan; Chromosome Engineering Research Center (CERC), Tottori University, Tottori 683-8503, Japan
| | - Kan Chiba
- Laboratory of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 260-8675, Japan
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