1
|
Kam MK, Park JY, Yun GH, Sohn HY, Park JH, Choi J, Koh YH, Jo C. Rottlerin Enhances the Autophagic Degradation of Phosphorylated Tau in Neuronal Cells. Mol Neurobiol 2024:10.1007/s12035-024-04182-9. [PMID: 38671330 DOI: 10.1007/s12035-024-04182-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 04/15/2024] [Indexed: 04/28/2024]
Abstract
Intra-neuronal accumulation of hyper-phosphorylated tau as neurofibrillary tangles (NFT) is a hallmark of Alzheimer's disease (AD). To prevent the aggregation of phosphorylated tau in neurons, decreasing the phosphorylated tau protein levels is important. Here, we examined the biological effects of rottlerin, a phytochemical compound extracted from the Kamala tree, Mallotus philippinensis, on phosphorylated tau levels. Notably, rottlerin decreased the levels of intracellular phosphorylated and total tau. A marked increase in the LC3-II, a hallmark of autophagy, was observed in these cells, indicating that rottlerin strongly induced autophagy. Interestingly, rottlerin induced the phosphorylation of Raptor at S792 through the activation of adenosine-monophosphate activated-protein kinase (AMPK), which likely inhibits the mammalian target of rapamycin complex 1 (mTORC1), thus resulting in the activation of transcription factor EB (TFEB), a master regulator of autophagy. In addition, nuclear factor erythroid 2-related factor 2 (Nrf2) activity increased in the presence of rottlerin. The decrease of phosphorylated tau levels in the presence of rottlerin was ameliorated by the knockdown of TFEB and partially attenuated by the knockout of the Nrf2 gene. Taken together, rottlerin likely enhances the degradation of phosphorylated tau through autophagy activated by TFEB and Nrf2. Thus, our results suggest that a natural compound rottlerin could be used as a preventive and therapeutic drug for AD.
Collapse
Affiliation(s)
- Min Kyoung Kam
- Division of Brain Disease Research, Department for Chronic Disease Convergence Research, Korea National Institute of Health, 187 Osongsaengmyeong2-Ro, Osong-Eup, Cheongju-Si, 363-951, Chungcheongbuk-Do, Korea
| | - Jee-Yun Park
- Division of Brain Disease Research, Department for Chronic Disease Convergence Research, Korea National Institute of Health, 187 Osongsaengmyeong2-Ro, Osong-Eup, Cheongju-Si, 363-951, Chungcheongbuk-Do, Korea
| | - Gwang Ho Yun
- Division of Brain Disease Research, Department for Chronic Disease Convergence Research, Korea National Institute of Health, 187 Osongsaengmyeong2-Ro, Osong-Eup, Cheongju-Si, 363-951, Chungcheongbuk-Do, Korea
| | - Hee-Young Sohn
- Division of Brain Disease Research, Department for Chronic Disease Convergence Research, Korea National Institute of Health, 187 Osongsaengmyeong2-Ro, Osong-Eup, Cheongju-Si, 363-951, Chungcheongbuk-Do, Korea
| | - Jung Hyun Park
- Division of Brain Disease Research, Department for Chronic Disease Convergence Research, Korea National Institute of Health, 187 Osongsaengmyeong2-Ro, Osong-Eup, Cheongju-Si, 363-951, Chungcheongbuk-Do, Korea
| | - Jiyoung Choi
- Division of Brain Disease Research, Department for Chronic Disease Convergence Research, Korea National Institute of Health, 187 Osongsaengmyeong2-Ro, Osong-Eup, Cheongju-Si, 363-951, Chungcheongbuk-Do, Korea
| | - Young Ho Koh
- Division of Brain Disease Research, Department for Chronic Disease Convergence Research, Korea National Institute of Health, 187 Osongsaengmyeong2-Ro, Osong-Eup, Cheongju-Si, 363-951, Chungcheongbuk-Do, Korea
| | - Chulman Jo
- Division of Brain Disease Research, Department for Chronic Disease Convergence Research, Korea National Institute of Health, 187 Osongsaengmyeong2-Ro, Osong-Eup, Cheongju-Si, 363-951, Chungcheongbuk-Do, Korea.
| |
Collapse
|
2
|
Su HY, Waldron RT, Gong R, Ramanujan VK, Pandol SJ, Lugea A. The Unfolded Protein Response Plays a Predominant Homeostatic Role in Response to Mitochondrial Stress in Pancreatic Stellate Cells. PLoS One 2016; 11:e0148999. [PMID: 26849807 PMCID: PMC4743835 DOI: 10.1371/journal.pone.0148999] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Accepted: 01/26/2016] [Indexed: 02/07/2023] Open
Abstract
Activated pancreatic stellate cells (PaSC) are key participants in the stroma of pancreatic cancer, secreting extracellular matrix proteins and inflammatory mediators. Tumors are poorly vascularized, creating metabolic stress conditions in cancer and stromal cells that necessitate adaptive homeostatic cellular programs. Activation of autophagy and the endoplasmic reticulum unfolded protein response (UPR) have been described in hepatic stellate cells, but the role of these processes in PaSC responses to metabolic stress is unknown. We reported that the PI3K/mTOR pathway, which AMPK can regulate through multiple inputs, modulates PaSC activation and fibrogenic potential. Here, using primary and immortalized mouse PaSC, we assess the relative contributions of AMPK/mTOR signaling, autophagy and the UPR to cell fate responses during metabolic stress induced by mitochondrial dysfunction. The mitochondrial uncoupler rottlerin at low doses (0.5-2.5 μM) was added to cells cultured in 10% FBS complete media. Mitochondria rapidly depolarized, followed by altered mitochondrial dynamics and decreased cellular ATP levels. This mitochondrial dysfunction elicited rapid, sustained AMPK activation, mTOR pathway inhibition, and blockade of autophagic flux. Rottlerin treatment also induced rapid, sustained PERK/CHOP UPR signaling. Subsequently, high doses (>5 μM) induced loss of cell viability and cell death. Interestingly, AMPK knock-down using siRNA did not prevent rottlerin-induced mTOR inhibition, autophagy, or CHOP upregulation, suggesting that AMPK is dispensable for these responses. Moreover, CHOP genetic deletion, but not AMPK knock-down, prevented rottlerin-induced apoptosis and supported cell survival, suggesting that UPR signaling is a major modulator of cell fate in PaSC during metabolic stress. Further, short-term rottlerin treatment reduced both PaSC fibrogenic potential and IL-6 mRNA expression. In contrast, expression levels of the angiogenic factors HGF and VEGFα were unaffected, and the immune modulator IL-4 was markedly upregulated. These data imply that metabolic stress-induced PaSC reprogramming differentially modulates neighboring cells in the tumor microenvironment.
Collapse
Affiliation(s)
- Hsin-Yuan Su
- Pancreatic Research Group, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
| | - Richard T. Waldron
- Pancreatic Research Group, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
- Department of Medicine, David Geffen School of Medicine, UCLA/VA Greater Los Angeles Health Sciences Center, Los Angeles, California, United States of America
| | - Raymond Gong
- Pancreatic Research Group, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
| | - V. Krishnan Ramanujan
- Department of Medicine, David Geffen School of Medicine, UCLA/VA Greater Los Angeles Health Sciences Center, Los Angeles, California, United States of America
- Metabolic Photonics Laboratory, Departments of Surgery and Biomedical Sciences, Cedars-Sinai Medical center, Los Angeles, California, United States of America
| | - Stephen J. Pandol
- Pancreatic Research Group, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
- Department of Medicine, David Geffen School of Medicine, UCLA/VA Greater Los Angeles Health Sciences Center, Los Angeles, California, United States of America
| | - Aurelia Lugea
- Pancreatic Research Group, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
- Department of Medicine, David Geffen School of Medicine, UCLA/VA Greater Los Angeles Health Sciences Center, Los Angeles, California, United States of America
- * E-mail:
| |
Collapse
|
3
|
Torricelli C, Daveri E, Salvadori S, Valacchi G, Ietta F, Muscettola M, Carlucci F, Maioli E. Phosphorylation-independent mTORC1 inhibition by the autophagy inducer Rottlerin. Cancer Lett 2015; 360:17-27. [PMID: 25661734 DOI: 10.1016/j.canlet.2015.01.040] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Revised: 01/26/2015] [Accepted: 01/27/2015] [Indexed: 02/07/2023]
Abstract
We recently found that Rottlerin not only inhibits proliferation but also causes Bcl-2- and Beclin 1-independent autophagic death in apoptosis-resistant breast adenocarcinoma MCF-7 cells. Having excluded a role for canonical signaling pathways, the current study was aimed to investigate the contribution of the AMPK/mTOR axis in autophagy induction and to search for the upstream signaling molecules potentially targeted by Rottlerin. Using several enzyme inhibitors, Western blotting analysis, mTOR siRNA and pull down assay, we demonstrate that the Rottlerin-triggered autophagy is mediated by inhibition of mTORC1 activity through a novel AMPK and mTORC1 phosphorylation-independent mechanism, likely mediated by the direct interaction between Rottlerin and mTOR.
Collapse
Affiliation(s)
- C Torricelli
- Department of Life Sciences, University of Siena, via Aldo Moro, Siena 7-53100, Italy
| | - E Daveri
- Department of Life Sciences, University of Siena, via Aldo Moro, Siena 7-53100, Italy
| | - S Salvadori
- Department of Life Sciences, University of Siena, via Aldo Moro, Siena 7-53100, Italy
| | - G Valacchi
- Department of Biology and Evolution, University of Ferrara, Via Luigi Borsari 46, Ferrara 44100, Italy; Department of Food and Nutrition, Kyung Hee University, Seoul 130-701, Republic of Korea
| | - F Ietta
- Department of Life Sciences, University of Siena, via Aldo Moro, Siena 7-53100, Italy
| | - M Muscettola
- Department of Medicine, surgery and neuroscience, University of Siena, Strada delle Scotte, Siena 4-53100, Italy
| | - F Carlucci
- Department of Medical biotechnologies, University of Siena, Strada delle Scotte, Siena 4-53100, Italy
| | - E Maioli
- Department of Life Sciences, University of Siena, via Aldo Moro, Siena 7-53100, Italy.
| |
Collapse
|
4
|
Lu W, Lin C, Li Y. Rottlerin induces Wnt co-receptor LRP6 degradation and suppresses both Wnt/β-catenin and mTORC1 signaling in prostate and breast cancer cells. Cell Signal 2014; 26:1303-9. [PMID: 24607787 DOI: 10.1016/j.cellsig.2014.02.018] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Revised: 02/10/2014] [Accepted: 02/22/2014] [Indexed: 02/06/2023]
Abstract
Activation of Wnt/β-catenin signaling can result in up-regulation of mTORC1 signaling in cancer cells. The low density lipoprotein receptor-related protein-6 (LRP6) is an essential Wnt co-receptor for Wnt/β-catenin signaling. We found that rottlerin, a natural plant polyphenol, suppressed LRP6 expression and phosphorylation, and inhibited Wnt/β-catenin signaling in HEK293 cells. Furthermore, the inhibitory effects of rottlerin on LRP6 expression/phosphorylation and Wnt/β-catenin signaling were confirmed in human prostate cancer PC-3 and DU145 cells and breast cancer MDA-MB-231 and T-47D cells. Mechanistically, rottlerin promoted LRP6 degradation, but had no effects on LRP6 transcriptional activity. In addition, rottlerin-mediated LRP6 down-regulation was unrelated to activation of 5'-AMP-activated protein kinase (AMPK). Importantly, we also found that rottlerin inhibited mTORC1 signaling in prostate and breast cancer cells. Finally, we demonstrated that rottlerin was able to suppress the expression of cyclin D1 and survivin, two targets of both Wnt/β-catenin and mTORC1 signaling, in prostate and breast cancer cells, and displayed remarkable anticancer activity with IC(50) values between 0.7 and 1.7 μM for prostate cancer PC-3 and DU145 cells and breast cancer MDA-MB-231 and T-47D cells. The IC(50) values are comparable to those shown to suppress the activities of Wnt/β-catenin and mTORC1 signaling in prostate and breast cancer cells. Our data indicate that rottlerin is a novel LRP6 inhibitor and suppresses both Wnt/β-catenin and mTORC1 signaling in prostate and breast cancer cells, and that LRP6 represents a potential therapeutic target for cancers.
Collapse
Affiliation(s)
- Wenyan Lu
- Department of Biochemistry and Molecular Biology, Drug Discovery Division, Southern Research Institute, 2000 Ninth Avenue South, Birmingham, AL 35255, USA
| | - Cuihong Lin
- Department of Biochemistry and Molecular Biology, Drug Discovery Division, Southern Research Institute, 2000 Ninth Avenue South, Birmingham, AL 35255, USA; Department of Pharmacy, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China
| | - Yonghe Li
- Department of Biochemistry and Molecular Biology, Drug Discovery Division, Southern Research Institute, 2000 Ninth Avenue South, Birmingham, AL 35255, USA.
| |
Collapse
|
5
|
Maioli E, Torricelli C, Valacchi G. Rottlerin and cancer: novel evidence and mechanisms. ScientificWorldJournal 2012; 2012:350826. [PMID: 22272173 PMCID: PMC3259573 DOI: 10.1100/2012/350826] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2011] [Accepted: 11/14/2011] [Indexed: 12/26/2022] Open
Abstract
Because cancers are caused by deregulation of hundreds of genes, an ideal anticancer agent should target multiple gene products or signaling pathways simultaneously. Recently, extensive research has addressed the chemotherapeutic potential of plant-derived compounds. Among the ever-increasing list of naturally occurring anticancer agents, Rottlerin appears to have great potentiality for being used in chemotherapy because it affects several cell machineries involved in survival, apoptosis, autophagy, and invasion. The underlying mechanisms that have been described are diverse, and the final, cell-specific, Rottlerin outcome appears to result from a combination of signaling pathways at multiple levels. This paper seeks to summarize the multifocal signal modulatory properties of Rottlerin, which merit to be further exploited for successful prevention and treatment of cancer.
Collapse
Affiliation(s)
- E Maioli
- Department of Physiology, University of Siena, Aldo Moro Street, 53100 Siena, Italy.
| | | | | |
Collapse
|
6
|
Clements RT, Cordeiro B, Feng J, Bianchi C, Sellke FW. Rottlerin increases cardiac contractile performance and coronary perfusion through BKCa++ channel activation after cold cardioplegic arrest in isolated hearts. Circulation 2011; 124:S55-61. [PMID: 21911819 DOI: 10.1161/circulationaha.110.012112] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Cardioplegia and cardiopulmonary bypass (CP/CPB) subjects myocardium to complex injurious stimuli that can result in cardiomyocyte and vascular contractile abnormalities. Rottlerin, originally identified as a delta-protein kinase C inhibitor, has a number of known additional effects that may be beneficial in the setting of CP/CPB. We tested the hypothesis that rottlerin mitigates deleterious effects associated with CP/CPB. METHODS AND RESULTS Langendorff-perfused isolated rat hearts were subjected to 2 hours intermittent cold (10°C) CP (St Thomas II) followed by 30 minutes normothermic reperfusion. CP was delivered every 30 minutes for 1 minute. Hearts were treated with rottlerin 1 μmol/L (CP+R) (n=7) or without rottlerin (CP) (n=9), and the BK(Ca++) channel inhibitor paxilline 100 nmol/L was supplied in the CP. Hearts constantly perfused with KHB served as controls (n=6). Baseline parameters of cardiac function were similar between groups. CP resulted in reduced cardiac function (left ventricular diastolic pressure, 39 ± 3.8%; ± dP/dt, 32 ± 4.4%, -41 ± 5.1% decrease compared to baseline). Treatment with rottlerin 1 μmol/L significantly improved CP-induced cardiac function (left ventricular diastolic pressure, 20 ± 5.9%; ± dP/dt, 5.2 ± 4.5%, -11.6 ± 4.7% decrease versus baseline; P<0.05 CP+R versus CP). Rottlerin also caused a significant increase in coronary flow postreperfusion (CP, 34 ± 4.2% decrease from baseline; CP+R, 26 ± 9.6% increase over baseline; P=0.01). Independent of vascular effects, CP significantly decreased isolated myocyte contraction, which was restored by rottlerin treatment. The BK(Ca++) channel inhibitor greatly reduced the majority of beneficial effects associated with rottlerin. CONCLUSIONS Rottlerin significantly improves cardiac performance after CP arrest through improved cardiomyocyte contraction and coronary perfusion.
Collapse
Affiliation(s)
- Richard T Clements
- Cardiovascular Research Center, Department of Surgery, Rhode Island Hospital and Alpert Medical School, Brown University, Coro 5.230, 1 Hoppin St, Providence, RI 02903, USA.
| | | | | | | | | |
Collapse
|
7
|
Jeong JO, Kim JH, Ahn KT, Park HS, Jang WI, Park JH, Lee JH, Choi SW, Kim JM, Seong IW. Tumor Suppressor Serine/Threonine Kinase LKB1 Expression, Not Kinase Activity, Increased in the Vascular Smooth Muscle Cells and Neointima in the Rat Carotid Artery Injury Model. Korean Circ J 2010; 40:552-7. [PMID: 21217931 PMCID: PMC3008825 DOI: 10.4070/kcj.2010.40.11.552] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2009] [Accepted: 04/29/2010] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND AND OBJECTIVES Vascular smooth muscle cell (VSMC) proliferation is responsible for the restenosis of previously inserted coronary stents. Angiotensin II (Ang II) is known to regulate VSMC proliferation. LKB1, a serine/threonine kinase, interacts with the p53 pathway and acts as a tumor suppressor. MATERIALS AND METHODS We assessed the association of Ang II and the expression of LKB1 in primary cultured murine VSMCs and neointima of the Sprague Dawley rat carotid artery injury model. We created carotid balloon injuries and harvested the injured carotid arteries 14 days after the procedure. RESULTS Ang II increased LKB1 expression in a time-dependent manner and peaked at an Ang II concentration of 10(-7) mole/L in VSMCs. In the animal experiment, neointima was markedly increased after balloon injury compared to the control group. Immunohistochemical studies showed that LKB1 expression increased according to neointima thickness. Ang II augmented LKB1 expression after the injury. Western blot analysis of LKB1 with carotid artery lysate revealed the same pattern as LKB1 immunohistochemistry. Increased LKB1 expression started at 5 days after the balloon injury, and peaked at 14 days after the injury. Although LKB1 expression was increased after the injury, LKB1 kinase activity was not increased. Ang II or balloon-injury increased the expression of LKB1 although the LKB1 activity was reduced. CONCLUSION Ang II increased LKB1 expression in VSMCs and neointima. These findings were not kinase dependant.
Collapse
Affiliation(s)
- Jin-Ok Jeong
- Division of Cardiology, Department of Internal Medicine, Chungnam National University School of Medicine, Daejeon, Korea
| | | | | | | | | | | | | | | | | | | |
Collapse
|
8
|
Screen for chemical modulators of autophagy reveals novel therapeutic inhibitors of mTORC1 signaling. PLoS One 2009; 4:e7124. [PMID: 19771169 PMCID: PMC2742736 DOI: 10.1371/journal.pone.0007124] [Citation(s) in RCA: 285] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Accepted: 08/17/2009] [Indexed: 02/04/2023] Open
Abstract
Background Mammalian target of rapamycin complex 1 (mTORC1) is a protein kinase that relays nutrient availability signals to control numerous cellular functions including autophagy, a process of cellular self-eating activated by nutrient depletion. Addressing the therapeutic potential of modulating mTORC1 signaling and autophagy in human disease requires active chemicals with pharmacologically desirable properties. Methodology/Principal Findings Using an automated cell-based assay, we screened a collection of >3,500 chemicals and identified three approved drugs (perhexiline, niclosamide, amiodarone) and one pharmacological reagent (rottlerin) capable of rapidly increasing autophagosome content. Biochemical assays showed that the four compounds stimulate autophagy and inhibit mTORC1 signaling in cells maintained in nutrient-rich conditions. The compounds did not inhibit mTORC2, which also contains mTOR as a catalytic subunit, suggesting that they do not inhibit mTOR catalytic activity but rather inhibit signaling to mTORC1. mTORC1 inhibition and autophagosome accumulation induced by perhexiline, niclosamide or rottlerin were rapidly reversed upon drug withdrawal whereas amiodarone inhibited mTORC1 essentially irreversibly. TSC2, a negative regulator of mTORC1, was required for inhibition of mTORC1 signaling by rottlerin but not for mTORC1 inhibition by perhexiline, niclosamide and amiodarone. Transient exposure of immortalized mouse embryo fibroblasts to these drugs was not toxic in nutrient-rich conditions but led to rapid cell death by apoptosis in starvation conditions, by a mechanism determined in large part by the tuberous sclerosis complex protein TSC2, an upstream regulator of mTORC1. By contrast, transient exposure to the mTORC1 inhibitor rapamycin caused essentially irreversible mTORC1 inhibition, sustained inhibition of cell growth and no selective cell killing in starvation. Conclusion/Significance The observation that drugs already approved for human use can reversibly inhibit mTORC1 and stimulate autophagy should greatly facilitate the preclinical and clinical testing of mTORC1 inhibition for indications such as tuberous sclerosis, diabetes, cardiovascular disease and cancer.
Collapse
|