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Tanaka M, Kanazashi M, Kondo H, Fujino H. Methylglyoxal reduces resistance exercise-induced protein synthesis and anabolic signaling in rat tibialis anterior muscle. J Muscle Res Cell Motil 2024:10.1007/s10974-024-09680-w. [PMID: 39085712 DOI: 10.1007/s10974-024-09680-w] [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: 04/28/2024] [Accepted: 07/15/2024] [Indexed: 08/02/2024]
Abstract
Resistance exercise provides significant benefits to skeletal muscle, including hypertrophy and metabolic enhancements, supporting overall health and disease management. However, skeletal muscle responsiveness to resistance exercise is significantly reduced in conditions such as aging and diabetes. Recent reports suggest that glycation stress contributes to muscle atrophy and impaired exercise-induced muscle adaptation; however, its role in the muscle response to resistance exercise remains unclear. Therefore, in this study, we investigated whether methylglyoxal (MGO), a key factor in glycation stress, affects the acute responsiveness of skeletal muscles to resistance exercise, focusing on protein synthesis and the key signaling molecules. This study included 12 8-week-old male Sprague-Dawley rats divided into two groups: one received 0.5% MGO-supplemented drinking water (MGO group) and the other received regular water (control group). After 10 weeks, the left tibialis anterior muscle of each rat was subjected to electrical stimulation (ES) to mimic resistance exercise, with the right muscle serving as a non-stimulated control. Muscle protein-synthesis rates were evaluated with SUnSET, and phosphorylation levels of key signaling molecules (p70S6K and S6rp) were quantified using western blotting. In the control group, stimulated muscles exhibited significantly increased muscle protein synthesis and phosphorylation levels of p70S6K and S6rp. In the MGO group, these increases were attenuated, indicating that MGO treatment suppresses the adaptive response to resistance exercise. MGO diminishes the skeletal muscle's adaptive response to ES-simulated resistance exercise, affecting both muscle protein synthesis and key signaling molecules. The potential influence of glycation stress on the effectiveness of resistance exercise or ES emphasizes the need for individualized interventions in conditions of elevated glycation stress, such as diabetes and aging.
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Affiliation(s)
- Masayuki Tanaka
- Department of Physical Therapy, Faculty of Health Sciences, Okayama Healthcare Professional University, 3-2-18 Daiku, Kita-ku, Okayama-shi, Okayama, 700-0913, Japan
- Department of Physical Therapy, Faculty of Human Sciences, Osaka University of Human Sciences, 1-4-1 Shojaku, Settsu-shi, Osaka, 566-8501, Japan
- Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, 7-10-2 Tomogaoka, Suma-ku, Kobe-shi, Hyogo, 654-0142, Japan
| | - Miho Kanazashi
- Department of Health and Welfare, Faculty of Health and Welfare, Prefectural University of Hiroshima, 1-1 Gakuen- cho, Mihara-shi, Hiroshima, 723-0053, Japan.
| | - Hiroyo Kondo
- Department of Nutrition, Faculty of Health and Nutrition, Shubun University, 6 Nikko-cho, Ichinomiya, Aichi, 491- 0938, Japan
| | - Hidemi Fujino
- Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, 7-10-2 Tomogaoka, Suma-ku, Kobe-shi, Hyogo, 654-0142, Japan
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2
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Nair KA, Liu B. Navigating the landscape of the unfolded protein response in CD8 + T cells. Front Immunol 2024; 15:1427859. [PMID: 39026685 PMCID: PMC11254671 DOI: 10.3389/fimmu.2024.1427859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2024] [Accepted: 06/24/2024] [Indexed: 07/20/2024] Open
Abstract
Endoplasmic reticulum stress occurs due to large amounts of misfolded proteins, hypoxia, nutrient deprivation, and more. The unfolded protein is a complex intracellular signaling network designed to operate under this stress. Composed of three individual arms, inositol-requiring enzyme 1, protein kinase RNA-like ER kinase, and activating transcription factor-6, the unfolded protein response looks to resolve stress and return to proteostasis. The CD8+ T cell is a critical cell type for the adaptive immune system. The unfolded protein response has been shown to have a wide-ranging spectrum of effects on CD8+ T cells. CD8+ T cells undergo cellular stress during activation and due to environmental insults. However, the magnitude of the effects this response has on CD8+ T cells is still understudied. Thus, studying these pathways is important to unraveling the inner machinations of these powerful cells. In this review, we will highlight the recent literature in this field, summarize the three pathways of the unfolded protein response, and discuss their roles in CD8+ T cell biology and functionality.
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Affiliation(s)
- Keith Alan Nair
- Division of Hematology, Department of Internal Medicine, The Ohio State University Comprehensive Cancer Center, Columbus, OH, United States
- The Pelotonia Institute for Immuno-Oncology, The Ohio State University Comprehensive Cancer Center, Columbus, OH, United States
| | - Bei Liu
- Division of Hematology, Department of Internal Medicine, The Ohio State University Comprehensive Cancer Center, Columbus, OH, United States
- The Pelotonia Institute for Immuno-Oncology, The Ohio State University Comprehensive Cancer Center, Columbus, OH, United States
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3
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Tabaka O, Lawal S, Del Rio Triana R, Hou M, Fraser A, Gallagher A, San Agustin Ruiz K, Marmarcz M, Dickinson M, Oliveira MM, Klann E, Shrestha P. Aberrant TSC-Rheb axis in Oxytocin receptor+ cells mediate stress-induced anxiety. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.25.600464. [PMID: 38979197 PMCID: PMC11230205 DOI: 10.1101/2024.06.25.600464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
Stress is a major risk for the onset of several maladaptive processes including pathological anxiety, a diffuse state of heightened apprehension over anticipated threats1. Pathological anxiety is prevalent in up to 59% of patients with Tuberous Sclerosis complex (TSC)2, a neurodevelopmental disorder (NDD) caused by loss-of-function mutations in genes for Tuberin (Tsc2) and/or Hamartin (Tsc1) that together comprise the eponymous protein complex. Here, we generated cell type-specific heterozygous knockout of Tsc2 in cells expressing oxytocin receptor (OTRCs) to model pathological anxiety-like behaviors observed in TSC patient population. The stress of prolonged social isolation induces a sustained negative affective state that precipitates behavioral avoidance, often by aberrant oxytocin signaling in the limbic forebrain3,4. In response to social isolation, there were striking sex differences in stress susceptibility in conditional heterozygote mice when encountering situations of approach-avoidance conflict. Socially isolated male mutants exhibited behavioral avoidance in anxiogenic environments and sought more social interaction for buffering of stress. In contrast, female mutants developed resilience during social isolation and approached anxiogenic environments, while devaluing social interaction. Systemic and medial prefrontal cortex (mPFC)-specific inhibition of downstream effector of TSC, the integrated stress response (ISR), rescued behavioral approach toward anxiogenic environments and conspecifics in male and female mutant mice respectively. Further, we found that Tsc2 deletion in OTRCs leads to OTR-signaling elicited network suppression, i.e., hypofrontality, in male mPFC, which is relieved by inhibiting the ISR. Our findings present evidence in support of a sexually dimorphic role of prefrontal OTRCs in regulating emotional responses in anxiogenic environments, which goes awry in TSC. Our work has broader implications for developing effective treatments for subtypes of anxiety disorders that are characterized by cell-autonomous ISR and prefrontal network suppression.
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Affiliation(s)
- Olivia Tabaka
- Department of Neurobiology & Behavior, Stony Brook University, Stony Brook, NY 11794
| | - Saheed Lawal
- Department of Neurobiology & Behavior, Stony Brook University, Stony Brook, NY 11794
| | | | - Mian Hou
- Center for Neural Science, New York University, New York, NY 10003
| | - Alexandra Fraser
- Department of Neurobiology & Behavior, Stony Brook University, Stony Brook, NY 11794
| | - Andrew Gallagher
- Department of Neurobiology & Behavior, Stony Brook University, Stony Brook, NY 11794
| | | | - Maggie Marmarcz
- Center for Neural Science, New York University, New York, NY 10003
| | - Matthew Dickinson
- Department of Neurobiology & Behavior, Stony Brook University, Stony Brook, NY 11794
| | | | - Eric Klann
- Center for Neural Science, New York University, New York, NY 10003
| | - Prerana Shrestha
- Department of Neurobiology & Behavior, Stony Brook University, Stony Brook, NY 11794
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4
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Karalis V, Wood D, Teaney NA, Sahin M. The role of TSC1 and TSC2 proteins in neuronal axons. Mol Psychiatry 2024; 29:1165-1178. [PMID: 38212374 DOI: 10.1038/s41380-023-02402-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Revised: 12/20/2023] [Accepted: 12/22/2023] [Indexed: 01/13/2024]
Abstract
Tuberous Sclerosis Complex 1 and 2 proteins, TSC1 and TSC2 respectively, participate in a multiprotein complex with a crucial role for the proper development and function of the nervous system. This complex primarily acts as an inhibitor of the mechanistic target of rapamycin (mTOR) kinase, and mutations in either TSC1 or TSC2 cause a neurodevelopmental disorder called Tuberous Sclerosis Complex (TSC). Neurological manifestations of TSC include brain lesions, epilepsy, autism, and intellectual disability. On the cellular level, the TSC/mTOR signaling axis regulates multiple anabolic and catabolic processes, but it is not clear how these processes contribute to specific neurologic phenotypes. Hence, several studies have aimed to elucidate the role of this signaling pathway in neurons. Of particular interest are axons, as axonal defects are associated with severe neurocognitive impairments. Here, we review findings regarding the role of the TSC1/2 protein complex in axons. Specifically, we will discuss how TSC1/2 canonical and non-canonical functions contribute to the formation and integrity of axonal structure and function.
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Affiliation(s)
- Vasiliki Karalis
- Rosamund Stone Zander Translational Neuroscience Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, 02115, USA
- FM Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, 02115, USA
| | - Delaney Wood
- FM Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, 02115, USA
- Human Neuron Core, Boston Children's Hospital, Boston, MA, 02115, USA
| | - Nicole A Teaney
- Rosamund Stone Zander Translational Neuroscience Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, 02115, USA
- FM Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, 02115, USA
| | - Mustafa Sahin
- Rosamund Stone Zander Translational Neuroscience Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, 02115, USA.
- FM Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, 02115, USA.
- Human Neuron Core, Boston Children's Hospital, Boston, MA, 02115, USA.
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5
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Rahman M, Nguyen TM, Lee GJ, Kim B, Park MK, Lee CH. Unraveling the Role of Ras Homolog Enriched in Brain (Rheb1 and Rheb2): Bridging Neuronal Dynamics and Cancer Pathogenesis through Mechanistic Target of Rapamycin Signaling. Int J Mol Sci 2024; 25:1489. [PMID: 38338768 PMCID: PMC10855792 DOI: 10.3390/ijms25031489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 01/14/2024] [Accepted: 01/17/2024] [Indexed: 02/12/2024] Open
Abstract
Ras homolog enriched in brain (Rheb1 and Rheb2), small GTPases, play a crucial role in regulating neuronal activity and have gained attention for their implications in cancer development, particularly in breast cancer. This study delves into the intricate connection between the multifaceted functions of Rheb1 in neurons and cancer, with a specific focus on the mTOR pathway. It aims to elucidate Rheb1's involvement in pivotal cellular processes such as proliferation, apoptosis resistance, migration, invasion, metastasis, and inflammatory responses while acknowledging that Rheb2 has not been extensively studied. Despite the recognized associations, a comprehensive understanding of the intricate interplay between Rheb1 and Rheb2 and their roles in both nerve and cancer remains elusive. This review consolidates current knowledge regarding the impact of Rheb1 on cancer hallmarks and explores the potential of Rheb1 as a therapeutic target in cancer treatment. It emphasizes the necessity for a deeper comprehension of the molecular mechanisms underlying Rheb1-mediated oncogenic processes, underscoring the existing gaps in our understanding. Additionally, the review highlights the exploration of Rheb1 inhibitors as a promising avenue for cancer therapy. By shedding light on the complicated roles between Rheb1/Rheb2 and cancer, this study provides valuable insights to the scientific community. These insights are instrumental in guiding the identification of novel targets and advancing the development of effective therapeutic strategies for treating cancer.
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Affiliation(s)
- Mostafizur Rahman
- College of Pharmacy, Dongguk University, Seoul 04620, Republic of Korea; (M.R.); (G.J.L.)
| | - Tuan Minh Nguyen
- College of Pharmacy, Dongguk University, Seoul 04620, Republic of Korea; (M.R.); (G.J.L.)
| | - Gi Jeong Lee
- College of Pharmacy, Dongguk University, Seoul 04620, Republic of Korea; (M.R.); (G.J.L.)
| | - Boram Kim
- College of Pharmacy, Dongguk University, Seoul 04620, Republic of Korea; (M.R.); (G.J.L.)
| | - Mi Kyung Park
- Department of BioHealthcare, Hwasung Medi-Science University, Hwaseong-si 18274, Republic of Korea
| | - Chang Hoon Lee
- College of Pharmacy, Dongguk University, Seoul 04620, Republic of Korea; (M.R.); (G.J.L.)
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6
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Jung DM, Kim KK, Kim EM. Chloromethylisothiazolinone induces ER stress-induced stress granule formation in human keratinocytes. Anim Cells Syst (Seoul) 2023; 27:171-179. [PMID: 37636324 PMCID: PMC10448836 DOI: 10.1080/19768354.2023.2250852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 08/09/2023] [Accepted: 08/18/2023] [Indexed: 08/29/2023] Open
Abstract
Chloromethylisothiazolinone (CMIT), a humidifier disinfectant, is known to be toxic to the respiratory system. While the toxic effect of CMIT on the lungs has been widely investigated, its effect on the skin is well unknown. In this study, we examined stress granule (SG) formation to investigate the cytotoxic effects of CMIT on human keratinocytes. We assessed the viability of the cells following CMIT exposure and performed immunofluorescence microscopy and immunoblot analyses to determine SG formation and downstream pathways. The IC50 values in human keratinocyte HaCaT cells after CMIT exposure for 1 and 24 h were 11 and 8 μg/mL, respectively, showing no significant difference. As determined using immunofluorescence microscopy, SG formation was effectively induced after CMIT exposure. Moreover, the phosphorylation of eukaryotic initiation factor-2α (eIF2α), a translation initiation factor, and protein kinase R-like endoplasmic reticulum (ER) kinase, which plays a role in the ER stress-mediated eIF2α phosphorylation, was confirmed by CMIT exposure. These results suggest that exposure to CMIT can have detrimental effects on the skin, even briefly, by inducing SG formation through ER stress in keratinocytes.
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Affiliation(s)
- Da-Min Jung
- Department of Biochemistry, College of Natural Sciences, Chungnam National University, Daejeon, Republic of Korea
| | - Kee K. Kim
- Department of Biochemistry, College of Natural Sciences, Chungnam National University, Daejeon, Republic of Korea
| | - Eun-Mi Kim
- Department of Predictive Toxicology, Korea Institute of Toxicology, Daejeon, Republic of Korea
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7
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Kanazashi M, Tanaka M. Acute effect of electrical stimulation on muscle protein synthesis and break-down in the soleus muscle of hindlimb unloaded rats. Biomed Res 2023; 44:209-218. [PMID: 37779033 DOI: 10.2220/biomedres.44.209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/03/2023]
Abstract
Electrical stimulation (ES) is effective for disuse-induced muscle atrophy. However, the acute effect of ES on muscle protein synthesis (MPS) and muscle protein breakdown (MPB) remains unclear. We investigated the effect of a single-session ES treatment on mTORC1 signaling, MPS, and MPB in the soleus muscle of 2-week hindlimb unloaded rats. Sprague Dawley rats (n = 12 male) were randomly divided into control (CON) and hindlimb unloaded (HU) groups. After 2 weeks, the right soleus muscle was percutaneously stimulated and underwent supramaximal isometric contractions. The left soleus muscle served as an internal control. We collected soleus muscle samples 6 h after ES. Two weeks of HU decreased p70S6K and S6rp activation, downstream factors for mTORC1 signaling, and SUnSET method-assessed MPS, but increased the LC3-II/I ratio, an indicator of autophagy. ES on disused muscle successfully activated mTORC1 signaling but did not affect MPS. Contrary, ES decreased ubiquitinated proteins expression and LC3B-II/I ratio. HU might affect mTORC1 activation and MPS differently in response to acute ES possibly due to excessive ROS production caused by ES. Our findings suggest that ES applied to disused skeletal muscles may suppress MPB, but its effect on MPS appears to be attenuated.
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Affiliation(s)
- Miho Kanazashi
- Department of Physical Therapy, Faculty of Health and Welfare, Prefectural University of Hiroshima, 1-1 Gakuen-cho, Mihara-shi, Hiroshima 723-0053, Japan
| | - Masayuki Tanaka
- Department of Physical Therapy, Faculty of Health Sciences, Okayama Healthcare Professional Uni- versity, 3-2-18 Daiku, Kita-ku, Okayama-shi, Okayama 700-0913, Japan
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8
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Keane L, Antignano I, Riechers SP, Zollinger R, Dumas AA, Offermann N, Bernis ME, Russ J, Graelmann F, McCormick PN, Esser J, Tejera D, Nagano A, Wang J, Chelala C, Biederbick Y, Halle A, Salomoni P, Heneka MT, Capasso M. mTOR-dependent translation amplifies microglia priming in aging mice. J Clin Invest 2021; 131:132727. [PMID: 33108356 DOI: 10.1172/jci132727] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Accepted: 10/14/2020] [Indexed: 12/20/2022] Open
Abstract
Microglia maintain homeostasis in the brain. However, with age, they become primed and respond more strongly to inflammatory stimuli. We show here that microglia from aged mice had upregulated mTOR complex 1 signaling controlling translation, as well as protein levels of inflammatory mediators. Genetic ablation of mTOR signaling showed a dual yet contrasting effect on microglia priming: it caused an NF-κB-dependent upregulation of priming genes at the mRNA level; however, mice displayed reduced cytokine protein levels, diminished microglia activation, and milder sickness behavior. The effect on translation was dependent on reduced phosphorylation of 4EBP1, resulting in decreased binding of eIF4E to eIF4G. Similar changes were present in aged human microglia and in damage-associated microglia, indicating that upregulation of mTOR-dependent translation is an essential aspect of microglia priming in aging and neurodegeneration.
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Affiliation(s)
- Lily Keane
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany.,Centre for Tumour Microenvironment and
| | | | | | | | | | - Nina Offermann
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Maria E Bernis
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Jenny Russ
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | | | | | - Julia Esser
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Dario Tejera
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Ai Nagano
- Centre for Cancer Genomics and Computational Biology, Barts Cancer Institute, Queen Mary University of London, London, United Kingdom
| | - Jun Wang
- Centre for Cancer Genomics and Computational Biology, Barts Cancer Institute, Queen Mary University of London, London, United Kingdom
| | - Claude Chelala
- Centre for Cancer Genomics and Computational Biology, Barts Cancer Institute, Queen Mary University of London, London, United Kingdom
| | | | - Annett Halle
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Paolo Salomoni
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Michael T Heneka
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Melania Capasso
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany.,Centre for Tumour Microenvironment and
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9
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Uddin MS, Yu WS, Lim LW. Exploring ER stress response in cellular aging and neuroinflammation in Alzheimer's disease. Ageing Res Rev 2021; 70:101417. [PMID: 34339860 DOI: 10.1016/j.arr.2021.101417] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 07/27/2021] [Accepted: 07/28/2021] [Indexed: 02/06/2023]
Abstract
One evident hallmark of Alzheimer's disease (AD) is the irregular accumulation of proteins due to changes in proteostasis involving endoplasmic reticulum (ER) stress. To alleviate ER stress and reinstate proteostasis, cells undergo an integrated signaling cascade called the unfolded protein response (UPR) that reduces the number of misfolded proteins and inhibits abnormal protein accumulation. Aging is associated with changes in the expression of ER chaperones and folding enzymes, leading to the impairment of proteostasis, and accumulation of misfolded proteins. The disrupted initiation of UPR prevents the elimination of unfolded proteins, leading to ER stress. In AD, the accumulation of misfolded proteins caused by sustained cellular stress leads to neurodegeneration and neuronal death. Current research has revealed that ER stress can trigger an inflammatory response through diverse transducers of UPR. Although the involvement of a neuroinflammatory component in AD has been documented for decades, whether it is a contributing factor or part of the neurodegenerative events is so far unknown. Besides, a feedback loop occurs between neuroinflammation and ER stress, which is strongly associated with neurodegenerative processes in AD. In this review, we focus on the current research on ER stress and UPR in cellular aging and neuroinflammatory processes, leading to memory impairment and synapse dysfunction in AD.
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10
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Watanabe Y, Sasaki T, Miyoshi S, Shimizu M, Yamauchi Y, Sato R. Insulin-induced genes INSIG1 and INSIG2 mediate oxysterol-dependent activation of the PERK-eIF2α-ATF4 axis. J Biol Chem 2021; 297:100989. [PMID: 34298014 PMCID: PMC8363831 DOI: 10.1016/j.jbc.2021.100989] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 07/12/2021] [Accepted: 07/19/2021] [Indexed: 11/06/2022] Open
Abstract
Insulin-induced genes (INSIGs) encode endoplasmic reticulum–resident proteins that regulate intracellular cholesterol metabolism. Oxysterols are oxygenated derivatives of cholesterol, some of which orchestrate lipid metabolism via interaction with INSIGs. Recently, it was reported that expression of activating transcription factor-4 (ATF4) was induced by certain oxysterols; the precise of mechanism is unclear. Herein, we show that INSIGs mediate ATF4 upregulation upon interaction with oxysterol. Oxysterols that possess a high affinity for INSIG, such as 27- and 25-hydroxycholesterol (25HC), markedly induced the increase of ATF4 protein when compared with other oxysterols. In addition, ATF4 upregulation by these oxysterols was attenuated in INSIG1/2-deficient Chinese hamster ovary cells and recovered by either INSIG1 or INSIG2 rescue. Mechanistic studies revealed that the binding of 25HC to INSIG is critical for increased ATF4 protein via activation of protein kinase RNA-activated–like ER kinase and eukaryotic translation initiation factor 2α. Knockout of INSIG1 or INSIG2 in human hepatoma Huh7 cells attenuated ATF4 protein upregulation, indicating that only one of the endogenous INSIGs, unlike overexpression of intrinsic INSIG1 or INSIG2, was insufficient for ATF4 induction. Furthermore, ATF4 proactively upregulated the cell death–inducible gene expression, such as Chop, Chac1, and Trb3, thereby markedly reducing cell viability with 25HC. These findings support a model whereby that INSIGs sense an increase in oxysterol in the endoplasmic reticulum and induce an increase of ATF4 protein via the protein kinase RNA-activated–like ER kinase–eukaryotic translation initiation factor 2α pathway, thereby promoting cell death.
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Affiliation(s)
- Yuichi Watanabe
- Food Biochemistry Laboratory, Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo, Japan
| | - Takashi Sasaki
- Food Biochemistry Laboratory, Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo, Japan
| | - Shoko Miyoshi
- Food Biochemistry Laboratory, Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo, Japan
| | - Makoto Shimizu
- Nutri-Life Science Laboratory, Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo, Japan
| | - Yoshio Yamauchi
- Food Biochemistry Laboratory, Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo, Japan
| | - Ryuichiro Sato
- Food Biochemistry Laboratory, Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo, Japan; Nutri-Life Science Laboratory, Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo, Japan; AMED-CREST, Japan Agency for Medical Research and Development, Tokyo, Japan.
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11
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Boksha IS, Prokhorova TA, Tereshkina EB, Savushkina OK, Burbaeva GS. Protein Phosphorylation Signaling Cascades in Autism: The Role of mTOR Pathway. BIOCHEMISTRY (MOSCOW) 2021; 86:577-596. [PMID: 33993859 DOI: 10.1134/s0006297921050072] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The mammalian target of rapamycin (mTOR) signaling pathway is a central regulator of cell metabolism, growth, and survival in response to hormones, growth factors, nutrients, and stress-induced signals. In this review, we analyzed the studies on the molecular abnormalities of the mTOR-associated signaling cascades in autism spectrum disorders (ASDs) and outlined the prospects for the pathogenicity-targeting pharmacotherapeutic approaches to ASDs, in particular syndromic ASDs. Based on available experimental and clinical data, we suggest that very early detection of molecular abnormalities in the ASD risk groups can be facilitated by using peripheral blood platelets. Also, identification of the time window of critical dysregulations in the described pathways in the ASD risk groups might suggest further research directions leading to more efficacious pharmacotherapeutic interventions in ASDs.
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Affiliation(s)
- Irina S Boksha
- Mental Health Research Center, Moscow, 115522, Russia. .,Gamaleya Research Center of Epidemiology and Microbiology, Ministry of Health of the Russian Federation, Moscow, 123098, Russia
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12
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Marzuca-Nassr GN, Kuwabara WMT, Vitzel KF, Murata GM, Torres RP, Mancini-Filho J, Alba-Loureiro TC, Curi R. Endoplasmic Reticulum Stress and Autophagy Markers in Soleus Muscle Disuse-Induced Atrophy of Rats Treated with Fish Oil. Nutrients 2021; 13:nu13072298. [PMID: 34371808 PMCID: PMC8308346 DOI: 10.3390/nu13072298] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 06/29/2021] [Accepted: 06/30/2021] [Indexed: 12/13/2022] Open
Abstract
Endoplasmic reticulum stress (ERS) and autophagy pathways are implicated in disuse muscle atrophy. The effects of high eicosapentaenoic (EPA) or high docosahexaenoic (DHA) fish oils on soleus muscle ERS and autophagy markers were investigated in a rat hindlimb suspension (HS) atrophy model. Adult Wistar male rats received daily by gavage supplementation (0.3 mL per 100 g b.w.) of mineral oil or high EPA or high DHA fish oils (FOs) for two weeks. Afterward, the rats were subjected to HS and the respective treatments concomitantly for an additional two-week period. After four weeks, we evaluated ERS and autophagy markers in the soleus muscle. Results were analyzed using two-way analysis of variance (ANOVA) and Bonferroni post hoc test. Gastrocnemius muscle ω-6/ω-3 fatty acids (FAs) ratio was decreased by both FOs indicating the tissue incorporation of omega-3 fatty acids. HS altered (p < 0.05) the protein content (decreasing total p38 and BiP and increasing p-JNK2/total JNK2 ratio, and caspase 3) and gene expressions (decreasing BiP and increasing IRE1 and PERK) of ERS and autophagy (decreasing Beclin and increasing LC3 and ATG14) markers in soleus. Both FOs attenuated (p < 0.05) the increase in PERK and ATG14 expressions induced by HS. Thus, both FOs could potentially attenuate ERS and autophagy in skeletal muscles undergoing atrophy.
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Affiliation(s)
- Gabriel Nasri Marzuca-Nassr
- Department of Internal Medicine, Faculty of Medicine, Universidad de La Frontera, Temuco 4780000, Chile
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508-000, Brazil; (W.M.T.K.); (K.F.V.); (T.C.A.-L.); (R.C.)
- Correspondence: ; Tel.: +56-45-2596713
| | - Wilson Mitsuo Tatagiba Kuwabara
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508-000, Brazil; (W.M.T.K.); (K.F.V.); (T.C.A.-L.); (R.C.)
| | - Kaio Fernando Vitzel
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508-000, Brazil; (W.M.T.K.); (K.F.V.); (T.C.A.-L.); (R.C.)
- School of Health Sciences, College of Health, Massey University, Auckland 0745, New Zealand
| | - Gilson Masahiro Murata
- Nephrology Division, Medical Investigation Laboratory-29 (LIM-29), Medical School, University of São Paulo (FM-USP), São Paulo 01246-903, Brazil;
| | - Rosângela Pavan Torres
- Department of Lipids Laboratory, Food Science & Nutrition, Faculty of Pharmaceutical Science, University of São Paulo, São Paulo 05508-000, Brazil; (R.P.T.); (J.M.-F.)
| | - Jorge Mancini-Filho
- Department of Lipids Laboratory, Food Science & Nutrition, Faculty of Pharmaceutical Science, University of São Paulo, São Paulo 05508-000, Brazil; (R.P.T.); (J.M.-F.)
| | - Tatiana Carolina Alba-Loureiro
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508-000, Brazil; (W.M.T.K.); (K.F.V.); (T.C.A.-L.); (R.C.)
| | - Rui Curi
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508-000, Brazil; (W.M.T.K.); (K.F.V.); (T.C.A.-L.); (R.C.)
- Interdisciplinary Post-Graduate Program in Health Sciences, Cruzeiro do Sul University, São Paulo 01506-000, Brazil
- Butantan Institute, São Paulo 05508-040, Brazil
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13
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Lee HC, Fu CY, Lin CY, Hu JR, Huang TY, Lo KY, Tsai HY, Sheu JC, Tsai HJ. Poly(U)-specific endoribonuclease ENDOU promotes translation of human CHOP mRNA by releasing uORF element-mediated inhibition. EMBO J 2021; 40:e104123. [PMID: 33511665 PMCID: PMC8167367 DOI: 10.15252/embj.2019104123] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 11/18/2020] [Accepted: 11/30/2020] [Indexed: 12/24/2022] Open
Abstract
Upstream open reading frames (uORFs) are known to negatively affect translation of the downstream ORF. The regulatory proteins involved in relieving this inhibition are however poorly characterized. In response to cellular stress, eIF2α phosphorylation leads to an inhibition of global protein synthesis, while translation of specific factors such as CHOP is induced. We analyzed a 105‐nt inhibitory uORF in the transcript of human CHOP (huORFchop) and found that overexpression of the zebrafish or human ENDOU poly(U)‐endoribonuclease (Endouc or ENDOU‐1, respectively) increases CHOP mRNA translation also in the absence of stress. We also found that Endouc/ENDOU‐1 binds and cleaves the huORFchop transcript at position 80G‐81U, which induces CHOP translation independently of phosphorylated eIF2α. However, both ENDOU and phospho‐eIF2α are nonetheless required for maximal translation of CHOP mRNA. Increased levels of ENDOU shift a huORFchop reporter as well as endogenous CHOP transcripts from the monosome to polysome fraction, indicating an increase in translation. Furthermore, we found that the uncapped truncated huORFchop‐69‐105‐nt transcript contains an internal ribosome entry site (IRES), facilitating translation of the cleaved transcript. Therefore, we propose a model where ENDOU‐mediated transcript cleavage positively regulates CHOP translation resulting in increased CHOP protein levels upon stress. Specifically, CHOP transcript cleavage changes the configuration of huORFchop thereby releasing its inhibition and allowing the stalled ribosomes to resume translation of the downstream ORF.
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Affiliation(s)
- Hung-Chieh Lee
- Institute of Biomedical Sciences, Mackay Medical College, New Taipei City, Taiwan
| | - Chuan-Yang Fu
- Institute of Biomedical Sciences, Mackay Medical College, New Taipei City, Taiwan
| | - Cheng-Yung Lin
- Institute of Biomedical Sciences, Mackay Medical College, New Taipei City, Taiwan
| | - Jia-Rung Hu
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei, Taiwan
| | - Ting-Ying Huang
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei, Taiwan
| | - Kai-Yin Lo
- Department of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan
| | - Hsin-Yue Tsai
- Institute of Molecular Medicine, School of Medicine, National Taiwan University, Taipei, Taiwan
| | - Jin-Chuan Sheu
- Liver Disease Prevention and Treatment Research Foundation, Taipei, Taiwan
| | - Huai-Jen Tsai
- Institute of Biomedical Sciences, Mackay Medical College, New Taipei City, Taiwan.,Institute of Molecular and Cellular Biology, National Taiwan University, Taipei, Taiwan.,Department of Life Science, Fu Jen Catholic University, New Taipei, Taiwan
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14
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Eshraghi M, Karunadharma PP, Blin J, Shahani N, Ricci EP, Michel A, Urban NT, Galli N, Sharma M, Ramírez-Jarquín UN, Florescu K, Hernandez J, Subramaniam S. Mutant Huntingtin stalls ribosomes and represses protein synthesis in a cellular model of Huntington disease. Nat Commun 2021; 12:1461. [PMID: 33674575 PMCID: PMC7935949 DOI: 10.1038/s41467-021-21637-y] [Citation(s) in RCA: 57] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 01/29/2021] [Indexed: 02/08/2023] Open
Abstract
The polyglutamine expansion of huntingtin (mHTT) causes Huntington disease (HD) and neurodegeneration, but the mechanisms remain unclear. Here, we found that mHtt promotes ribosome stalling and suppresses protein synthesis in mouse HD striatal neuronal cells. Depletion of mHtt enhances protein synthesis and increases the speed of ribosomal translocation, while mHtt directly inhibits protein synthesis in vitro. Fmrp, a known regulator of ribosome stalling, is upregulated in HD, but its depletion has no discernible effect on protein synthesis or ribosome stalling in HD cells. We found interactions of ribosomal proteins and translating ribosomes with mHtt. High-resolution global ribosome footprint profiling (Ribo-Seq) and mRNA-Seq indicates a widespread shift in ribosome occupancy toward the 5' and 3' end and unique single-codon pauses on selected mRNA targets in HD cells, compared to controls. Thus, mHtt impedes ribosomal translocation during translation elongation, a mechanistic defect that can be exploited for HD therapeutics.
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Affiliation(s)
- Mehdi Eshraghi
- grid.214007.00000000122199231The Scripps Research Institute, Department of Neuroscience, Jupiter, FL USA
| | - Pabalu P. Karunadharma
- grid.214007.00000000122199231The Scripps Research Institute, Genomic Core, Jupiter, FL USA
| | - Juliana Blin
- grid.462957.b0000 0004 0598 0706Laboratory of Biology and Cellular Modelling at Ecole Normale Supérieure of Lyon, RNA Metabolism in Immunity and Infection Lab, LBMC, Lyon, France
| | - Neelam Shahani
- grid.214007.00000000122199231The Scripps Research Institute, Department of Neuroscience, Jupiter, FL USA
| | - Emiliano P. Ricci
- grid.462957.b0000 0004 0598 0706Laboratory of Biology and Cellular Modelling at Ecole Normale Supérieure of Lyon, RNA Metabolism in Immunity and Infection Lab, LBMC, Lyon, France
| | | | | | - Nicole Galli
- grid.214007.00000000122199231The Scripps Research Institute, Department of Neuroscience, Jupiter, FL USA
| | - Manish Sharma
- grid.214007.00000000122199231The Scripps Research Institute, Department of Neuroscience, Jupiter, FL USA
| | - Uri Nimrod Ramírez-Jarquín
- grid.214007.00000000122199231The Scripps Research Institute, Department of Neuroscience, Jupiter, FL USA
| | - Katie Florescu
- grid.214007.00000000122199231The Scripps Research Institute, Department of Neuroscience, Jupiter, FL USA
| | - Jennifer Hernandez
- grid.214007.00000000122199231The Scripps Research Institute, Department of Neuroscience, Jupiter, FL USA
| | - Srinivasa Subramaniam
- grid.214007.00000000122199231The Scripps Research Institute, Department of Neuroscience, Jupiter, FL USA
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15
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Nesterov SV, Yaguzhinsky LS, Podoprigora GI, Nartsissov YR. Amino Acids as Regulators of Cell Metabolism. BIOCHEMISTRY (MOSCOW) 2021; 85:393-408. [PMID: 32569548 DOI: 10.1134/s000629792004001x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
In this review, we discuss the principles of regulation and synchronization of metabolic processes in mammalian cells using a two-component model of cell metabolism consisting of a controlling signaling system that regulates major enzymatic cascades and executive metabolic system that directly performs biosynthetic reactions. This approach has allowed us to distinguish two transitional metabolic states (from catabolism to anabolism and vice versa) accompanied by major rearrangements in the signaling system. The signaling system of natural amino acids was selected, because amino acids are involved in both signaling and executive metabolic subsystems of general cell metabolism. We have developed a graphical representation of metabolic events that allowed us to demonstrate the succession of processes occurring in both metabolic subsystems during complete metabolic cycle in a non-dividing cell. An important revealed feature of the amino acid signaling system is that the signaling properties of amino acid are determined not only by their molecular structure, but also by the location within the cell. Four major signaling groups of amino acids have been identified that localize to lysosomes, mitochondria, cytosol, and extracellular space adjacent to the plasma membrane. Although these amino acids groups are similar in the composition, they have different receptors. We also proposed a scheme for the metabolism regulation by amino acids signaling that can serve as a basis for developing more complete spatio-temporal picture of metabolic regulation involving a wide variety of intracellular signaling cascades.
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Affiliation(s)
- S V Nesterov
- Institute of Cytochemistry and Molecular Pharmacology, Moscow, 115404, Russia.,Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141701, Russia
| | - L S Yaguzhinsky
- Institute of Cytochemistry and Molecular Pharmacology, Moscow, 115404, Russia. .,Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - G I Podoprigora
- Institute of Cytochemistry and Molecular Pharmacology, Moscow, 115404, Russia
| | - Ya R Nartsissov
- Institute of Cytochemistry and Molecular Pharmacology, Moscow, 115404, Russia
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16
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Chatterjee S, Chakrabarty Y, Banerjee S, Ghosh S, Bhattacharyya SN. Mitochondria control mTORC1 activity-linked compartmentalization of eIF4E to regulate extracellular export of microRNAs. J Cell Sci 2020; 133:jcs250241. [PMID: 33262313 DOI: 10.1242/jcs.250241] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 11/17/2020] [Indexed: 01/08/2023] Open
Abstract
Defective intracellular trafficking and export of microRNAs (miRNAs) have been observed in growth-retarded mammalian cells having impaired mitochondrial potential and dynamics. Here, we found that uncoupling protein 2 (Ucp2)-mediated depolarization of mitochondrial membrane also results in progressive sequestration of miRNAs within polysomes and lowers their release via extracellular vesicles. Interestingly, the impaired miRNA-trafficking process in growth-retarded human cells could be reversed in the presence of Genipin, an inhibitor of Ucp2. Mitochondrial detethering of endoplasmic reticulum (ER), observed in cells with depolarized mitochondria, was found to be responsible for defective compartmentalization of translation initiation factor eIF4E to polysomes attached to ER. This caused a retarded translation process accompanied by enhanced retention of miRNAs and target mRNAs within ER-attached polysomes to restrict extracellular export of miRNAs. Reduced compartment-specific activity of the mammalian target of rapamycin complex 1 (mTORC1), the master regulator of protein synthesis, in cells with defective mitochondria or detethered ER, caused reduced phosphorylation of eIF4E-BP1 and prevented eIF4E targeting to ER-attached polysomes and miRNA export. These data suggest how mitochondrial membrane potential and dynamics, by affecting mTORC1 activity and compartmentalization, determine the subcellular localization and export of miRNAs.
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Affiliation(s)
- Susanta Chatterjee
- RNA Biology Research Laboratory, Molecular Genetics Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700032, India
| | - Yogaditya Chakrabarty
- RNA Biology Research Laboratory, Molecular Genetics Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700032, India
| | - Saikat Banerjee
- RNA Biology Research Laboratory, Molecular Genetics Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700032, India
| | - Souvik Ghosh
- RNA Biology Research Laboratory, Molecular Genetics Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700032, India
| | - Suvendra N Bhattacharyya
- RNA Biology Research Laboratory, Molecular Genetics Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700032, India
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17
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Han S, Jeong YY, Sheshadri P, Su X, Cai Q. Mitophagy regulates integrity of mitochondria at synapses and is critical for synaptic maintenance. EMBO Rep 2020; 21:e49801. [PMID: 32627320 DOI: 10.15252/embr.201949801] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 06/01/2020] [Accepted: 06/05/2020] [Indexed: 01/25/2023] Open
Abstract
Synaptic mitochondria are particularly vulnerable to physiological insults, and defects in synaptic mitochondria are linked to early pathophysiology of Alzheimer's disease (AD). Mitophagy, a cargo-specific autophagy for elimination of dysfunctional mitochondria, constitutes a key quality control mechanism. However, how mitophagy ensures synaptic mitochondrial integrity remains largely unknown. Here, we reveal Rheb and Snapin as key players regulating mitochondrial homeostasis at synapses. Rheb initiates mitophagy to target damaged mitochondria for autophagy, whereas dynein-Snapin-mediated retrograde transport promotes clearance of mitophagosomes from synaptic terminals. We demonstrate that synaptic accumulation of mitophagosomes is a feature in AD-related mutant hAPP mouse brains, which is attributed to increased mitophagy initiation coupled with impaired removal of mitophagosomes from AD synapses due to defective retrograde transport. Furthermore, while deficiency in dynein-Snapin-mediated retrograde transport recapitulates synaptic mitophagy stress and induces synaptic degeneration, elevated Snapin expression attenuates mitochondrial defects and ameliorates synapse loss in AD mouse brains. Taken together, our study provides new insights into mitophagy regulation of synaptic mitochondrial integrity, establishing a foundation for mitigating AD-associated mitochondria deficits and synaptic damage through mitophagy enhancement.
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Affiliation(s)
- Sinsuk Han
- Division of Life Science, Department of Cell Biology and Neuroscience, School of Arts and Sciences, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Yu Young Jeong
- Division of Life Science, Department of Cell Biology and Neuroscience, School of Arts and Sciences, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Preethi Sheshadri
- Division of Life Science, Department of Cell Biology and Neuroscience, School of Arts and Sciences, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Xiao Su
- Division of Life Science, Department of Cell Biology and Neuroscience, School of Arts and Sciences, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Qian Cai
- Division of Life Science, Department of Cell Biology and Neuroscience, School of Arts and Sciences, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
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18
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Hetz C, Zhang K, Kaufman RJ. Mechanisms, regulation and functions of the unfolded protein response. Nat Rev Mol Cell Biol 2020; 21:421-438. [PMID: 32457508 DOI: 10.1038/s41580-020-0250-z] [Citation(s) in RCA: 1197] [Impact Index Per Article: 299.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/14/2020] [Indexed: 12/21/2022]
Abstract
Cellular stress induced by the abnormal accumulation of unfolded or misfolded proteins at the endoplasmic reticulum (ER) is emerging as a possible driver of human diseases, including cancer, diabetes, obesity and neurodegeneration. ER proteostasis surveillance is mediated by the unfolded protein response (UPR), a signal transduction pathway that senses the fidelity of protein folding in the ER lumen. The UPR transmits information about protein folding status to the nucleus and cytosol to adjust the protein folding capacity of the cell or, in the event of chronic damage, induce apoptotic cell death. Recent advances in the understanding of the regulation of UPR signalling and its implications in the pathophysiology of disease might open new therapeutic avenues.
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Affiliation(s)
- Claudio Hetz
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile. .,FONDAP Center for Geroscience Brain Health and Metabolism (GERO), Santiago, Chile. .,Program of Cellular and Molecular Biology, Institute of Biomedical Science, University of Chile, Santiago, Chile. .,Buck Institute for Research on Aging, Novato, CA, USA.
| | - Kezhong Zhang
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, USA. .,Department of Biochemistry, Microbiology and Immunology, Wayne State University School of Medicine, Detroit, MI, USA.
| | - Randal J Kaufman
- Degenerative Diseases Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA.
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19
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Ravi V, Jain A, Khan D, Ahamed F, Mishra S, Giri M, Inbaraj M, Krishna S, Sarikhani M, Maity S, Kumar S, Shah RA, Dave P, Pandit AS, Rajendran R, Desingu PA, Varshney U, Das S, Kolthur-Seetharam U, Rajakumari S, Singh M, Sundaresan NR. SIRT6 transcriptionally regulates global protein synthesis through transcription factor Sp1 independent of its deacetylase activity. Nucleic Acids Res 2019; 47:9115-9131. [PMID: 31372634 PMCID: PMC6755095 DOI: 10.1093/nar/gkz648] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 06/30/2019] [Accepted: 07/31/2019] [Indexed: 01/12/2023] Open
Abstract
Global protein synthesis is emerging as an important player in the context of aging and age-related diseases. However, the intricate molecular networks that regulate protein synthesis are poorly understood. Here, we report that SIRT6, a nuclear-localized histone deacetylase represses global protein synthesis by transcriptionally regulating mTOR signalling via the transcription factor Sp1, independent of its deacetylase activity. Our results suggest that SIRT6 deficiency increases protein synthesis in mice. Further, multiple lines of in vitro evidence suggest that SIRT6 negatively regulates protein synthesis in a cell-autonomous fashion and independent of its catalytic activity. Mechanistically, SIRT6 binds to the zinc finger DNA binding domain of Sp1 and represses its activity. SIRT6 deficiency increased the occupancy of Sp1 at key mTOR signalling gene promoters resulting in enhanced expression of these genes and activation of the mTOR signalling pathway. Interestingly, inhibition of either mTOR or Sp1 abrogated the increased protein synthesis observed under SIRT6 deficient conditions. Moreover, pharmacological inhibition of mTOR restored cardiac function in muscle-specific SIRT6 knockout mice, which spontaneously develop cardiac hypertrophy. Overall, these findings have unravelled a new layer of regulation of global protein synthesis by SIRT6, which can be potentially targeted to combat aging-associated diseases like cardiac hypertrophy.
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Affiliation(s)
- Venkatraman Ravi
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
| | - Aditi Jain
- Centre for BioSystems Science and Engineering, Indian Institute of Science, Bengaluru, India
| | - Danish Khan
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
| | - Faiz Ahamed
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
| | - Sneha Mishra
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
| | - Malyasree Giri
- Molecular Biophysics Unit, Indian Institute of Science, Bengaluru, India
| | - Meena Inbaraj
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
| | - Swati Krishna
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
| | - Mohsen Sarikhani
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
| | - Sangeeta Maity
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
| | - Shweta Kumar
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
| | - Riyaz Ahmad Shah
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
| | - Pratik Dave
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
| | - Anwit S Pandit
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
| | - Rajprabu Rajendran
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bengaluru, India
| | - Perumal A Desingu
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
| | - Umesh Varshney
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
| | - Saumitra Das
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
| | | | - Sona Rajakumari
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bengaluru, India
| | - Mahavir Singh
- Molecular Biophysics Unit, Indian Institute of Science, Bengaluru, India.,NMR Research Centre, Indian Institute of Science, Bengaluru, India
| | - Nagalingam R Sundaresan
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India.,Centre for BioSystems Science and Engineering, Indian Institute of Science, Bengaluru, India
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20
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Amino Acids License Kinase mTORC1 Activity and Treg Cell Function via Small G Proteins Rag and Rheb. Immunity 2019; 51:1012-1027.e7. [PMID: 31668641 DOI: 10.1016/j.immuni.2019.10.001] [Citation(s) in RCA: 80] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2019] [Revised: 09/17/2019] [Accepted: 09/27/2019] [Indexed: 12/17/2022]
Abstract
Regulatory T (Treg) cells are critical mediators of immune tolerance whose activity depends upon T cell receptor (TCR) and mTORC1 kinase signaling, but the mechanisms that dictate functional activation of these pathways are incompletely understood. Here, we showed that amino acids license Treg cell function by priming and sustaining TCR-induced mTORC1 activity. mTORC1 activation was induced by amino acids, especially arginine and leucine, accompanied by the dynamic lysosomal localization of the mTOR and Tsc complexes. Rag and Rheb GTPases were central regulators of amino acid-dependent mTORC1 activation in effector Treg (eTreg) cells. Mice bearing RagA-RagB- or Rheb1-Rheb2-deficient Treg cells developed a fatal autoimmune disease and had reduced eTreg cell accumulation and function. RagA-RagB regulated mitochondrial and lysosomal fitness, while Rheb1-Rheb2 enforced eTreg cell suppressive gene signature. Together, these findings reveal a crucial requirement of amino acid signaling for licensing and sustaining mTORC1 activation and functional programming of Treg cells.
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21
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Blackwood EA, Hofmann C, Santo Domingo M, Bilal AS, Sarakki A, Stauffer W, Arrieta A, Thuerauf DJ, Kolkhorst FW, Müller OJ, Jakobi T, Dieterich C, Katus HA, Doroudgar S, Glembotski CC. ATF6 Regulates Cardiac Hypertrophy by Transcriptional Induction of the mTORC1 Activator, Rheb. Circ Res 2019; 124:79-93. [PMID: 30582446 DOI: 10.1161/circresaha.118.313854] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE Endoplasmic reticulum (ER) stress dysregulates ER proteostasis, which activates the transcription factor, ATF6 (activating transcription factor 6α), an inducer of genes that enhance protein folding and restore ER proteostasis. Because of increased protein synthesis, it is possible that protein folding and ER proteostasis are challenged during cardiac myocyte growth. However, it is not known whether ATF6 is activated, and if so, what its function is during hypertrophic growth of cardiac myocytes. OBJECTIVE To examine the activity and function of ATF6 during cardiac hypertrophy. METHODS AND RESULTS We found that ER stress and ATF6 were activated and ATF6 target genes were induced in mice subjected to an acute model of transverse aortic constriction, or to free-wheel exercise, both of which promote adaptive cardiac myocyte hypertrophy with preserved cardiac function. Cardiac myocyte-specific deletion of Atf6 (ATF6 cKO [conditional knockout]) blunted transverse aortic constriction and exercise-induced cardiac myocyte hypertrophy and impaired cardiac function, demonstrating a role for ATF6 in compensatory myocyte growth. Transcript profiling and chromatin immunoprecipitation identified RHEB (Ras homologue enriched in brain) as an ATF6 target gene in the heart. RHEB is an activator of mTORC1 (mammalian/mechanistic target of rapamycin complex 1), a major inducer of protein synthesis and subsequent cell growth. Both transverse aortic constriction and exercise upregulated RHEB, activated mTORC1, and induced cardiac hypertrophy in wild type mouse hearts but not in ATF6 cKO hearts. Mechanistically, knockdown of ATF6 in neonatal rat ventricular myocytes blocked phenylephrine- and IGF1 (insulin-like growth factor 1)-mediated RHEB induction, mTORC1 activation, and myocyte growth, all of which were restored by ectopic RHEB expression. Moreover, adeno-associated virus 9- RHEB restored cardiac growth to ATF6 cKO mice subjected to transverse aortic constriction. Finally, ATF6 induced RHEB in response to growth factors, but not in response to other activators of ATF6 that do not induce growth, indicating that ATF6 target gene induction is stress specific. CONCLUSIONS Compensatory cardiac hypertrophy activates ER stress and ATF6, which induces RHEB and activates mTORC1. Thus, ATF6 is a previously unrecognized link between growth stimuli and mTORC1-mediated cardiac growth.
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Affiliation(s)
- Erik A Blackwood
- From the Department of Biology, San Diego State University Heart Institute, San Diego State University, CA (E.A.B., C.H., M.S.D., A.S.B., A.S., W.S., A.A., D.J.T., F.W.K., C.C.G.)
| | - Christoph Hofmann
- From the Department of Biology, San Diego State University Heart Institute, San Diego State University, CA (E.A.B., C.H., M.S.D., A.S.B., A.S., W.S., A.A., D.J.T., F.W.K., C.C.G.).,Department of Cardiology, Angiology, and Pneumology, University Hospital Heidelberg, Germany (C.H., O.J.M., H.A.K., S.D.).,German Centre for Cardiovascular Research, Partner Site Heidelberg (C.H., O.J.M., T.J., C.D., H.A.K., S.D.)
| | - Michelle Santo Domingo
- From the Department of Biology, San Diego State University Heart Institute, San Diego State University, CA (E.A.B., C.H., M.S.D., A.S.B., A.S., W.S., A.A., D.J.T., F.W.K., C.C.G.)
| | - Alina S Bilal
- From the Department of Biology, San Diego State University Heart Institute, San Diego State University, CA (E.A.B., C.H., M.S.D., A.S.B., A.S., W.S., A.A., D.J.T., F.W.K., C.C.G.)
| | - Anup Sarakki
- From the Department of Biology, San Diego State University Heart Institute, San Diego State University, CA (E.A.B., C.H., M.S.D., A.S.B., A.S., W.S., A.A., D.J.T., F.W.K., C.C.G.)
| | - Winston Stauffer
- From the Department of Biology, San Diego State University Heart Institute, San Diego State University, CA (E.A.B., C.H., M.S.D., A.S.B., A.S., W.S., A.A., D.J.T., F.W.K., C.C.G.)
| | - Adrian Arrieta
- From the Department of Biology, San Diego State University Heart Institute, San Diego State University, CA (E.A.B., C.H., M.S.D., A.S.B., A.S., W.S., A.A., D.J.T., F.W.K., C.C.G.)
| | - Donna J Thuerauf
- From the Department of Biology, San Diego State University Heart Institute, San Diego State University, CA (E.A.B., C.H., M.S.D., A.S.B., A.S., W.S., A.A., D.J.T., F.W.K., C.C.G.)
| | - Fred W Kolkhorst
- From the Department of Biology, San Diego State University Heart Institute, San Diego State University, CA (E.A.B., C.H., M.S.D., A.S.B., A.S., W.S., A.A., D.J.T., F.W.K., C.C.G.)
| | - Oliver J Müller
- Department of Cardiology, Angiology, and Pneumology, University Hospital Heidelberg, Germany (C.H., O.J.M., H.A.K., S.D.).,German Centre for Cardiovascular Research, Partner Site Heidelberg (C.H., O.J.M., T.J., C.D., H.A.K., S.D.).,Department of Internal Medicine III, University of Kiel, Germany, and German Centre for Cardiovascular Research, Partner Site Hamburg/Kiel/Lübeck, Germany (O.J.M.)
| | - Tobias Jakobi
- Department of Cardiology, Angiology, and Pneumology, University Hospital Heidelberg, Germany (C.H., O.J.M., H.A.K., S.D.).,German Centre for Cardiovascular Research, Partner Site Heidelberg (C.H., O.J.M., T.J., C.D., H.A.K., S.D.).,Section of Bioinformatics and Systems Cardiology, Department of Internal Medicine III, University Hospital Heidelberg, Germany (T.J., C.D.)
| | - Christoph Dieterich
- Department of Cardiology, Angiology, and Pneumology, University Hospital Heidelberg, Germany (C.H., O.J.M., H.A.K., S.D.).,German Centre for Cardiovascular Research, Partner Site Heidelberg (C.H., O.J.M., T.J., C.D., H.A.K., S.D.).,Section of Bioinformatics and Systems Cardiology, Department of Internal Medicine III, University Hospital Heidelberg, Germany (T.J., C.D.)
| | - Hugo A Katus
- Department of Cardiology, Angiology, and Pneumology, University Hospital Heidelberg, Germany (C.H., O.J.M., H.A.K., S.D.).,German Centre for Cardiovascular Research, Partner Site Heidelberg (C.H., O.J.M., T.J., C.D., H.A.K., S.D.)
| | - Shirin Doroudgar
- Department of Cardiology, Angiology, and Pneumology, University Hospital Heidelberg, Germany (C.H., O.J.M., H.A.K., S.D.).,German Centre for Cardiovascular Research, Partner Site Heidelberg (C.H., O.J.M., T.J., C.D., H.A.K., S.D.)
| | - Christopher C Glembotski
- From the Department of Biology, San Diego State University Heart Institute, San Diego State University, CA (E.A.B., C.H., M.S.D., A.S.B., A.S., W.S., A.A., D.J.T., F.W.K., C.C.G.)
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22
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Zhang Q, Hu J, Wu Y, Luo H, Meng W, Xiao B, Xiao X, Zhou Z, Liu F. Rheb (Ras Homolog Enriched in Brain 1) Deficiency in Mature Macrophages Prevents Atherosclerosis by Repressing Macrophage Proliferation, Inflammation, and Lipid Uptake. Arterioscler Thromb Vasc Biol 2019; 39:1787-1801. [DOI: 10.1161/atvbaha.119.312870] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Objective:
Macrophage foam cell formation is an important process in atherosclerotic plaque development. The small GTPase Rheb (Ras homolog enriched in brain 1) regulates endocytic trafficking that is critical for foam cell formation. However, it is unclear whether and how macrophage Rheb regulates atherogenesis, which are the focuses of the current study.
Approach and Results:
Immunofluorescence study confirmed the colocalization of Rheb in F4/80 and Mac-2 (galectin-3)–labeled lesional macrophages. Western blot and fluorescence-activated cell sorting analysis showed that Rheb expression was significantly increased in atherosclerotic lesions of atherosclerosis-prone (apoE
−/−
[apolipoprotein E deficient]) mice fed with Western diet. Increased Rheb expression was also observed in oxidized LDL (low-density lipoprotein)–treated macrophages. To investigate the in vivo role of macrophage Rheb, we established mature Rheb
mKO
(macrophage-specific Rheb knockout) mice by crossing the Rheb floxed mice with
F4/80-cre
mice. Macrophage-specific knockout of Rheb in mice reduced Western diet–induced atherosclerotic lesion by 32%, accompanied with a decrease in macrophage content in plaque. Mechanistically, loss of Rheb in macrophages repressed oxidized LDL–induced lipid uptake, inflammation, and macrophage proliferation. On the contrary, lentivirus-mediated overexpression of Rheb in macrophages increased oxidized LDL–induced lipid uptake and inflammation, and the stimulatory effect of Rheb was suppressed by the mTOR (mammalian target of rapamycin) inhibitor rapamycin or the PKA (protein kinase A) activator forskolin.
Conclusions:
Macrophage Rheb plays important role in Western diet–induced atherosclerosis by promoting macrophage proliferation, inflammation, and lipid uptake. Inhibition of expression and function of Rheb in macrophages is beneficial to prevent diet-induced atherosclerosis.
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Affiliation(s)
- Qinghai Zhang
- From the Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, National Clinical Research Center for Metabolic Diseases, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China (Q.Z., J.H., Y.W., H.L., W.M., B.X., Z.Z., F.L.)
- Department of Metabolism and Endocrinology, First Affiliated Hospital of University of South China, Hengyang, Hunan (Q.Z.)
| | - Jie Hu
- From the Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, National Clinical Research Center for Metabolic Diseases, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China (Q.Z., J.H., Y.W., H.L., W.M., B.X., Z.Z., F.L.)
| | - Yan Wu
- From the Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, National Clinical Research Center for Metabolic Diseases, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China (Q.Z., J.H., Y.W., H.L., W.M., B.X., Z.Z., F.L.)
| | - Hairong Luo
- From the Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, National Clinical Research Center for Metabolic Diseases, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China (Q.Z., J.H., Y.W., H.L., W.M., B.X., Z.Z., F.L.)
| | - Wen Meng
- From the Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, National Clinical Research Center for Metabolic Diseases, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China (Q.Z., J.H., Y.W., H.L., W.M., B.X., Z.Z., F.L.)
| | - Bo Xiao
- From the Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, National Clinical Research Center for Metabolic Diseases, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China (Q.Z., J.H., Y.W., H.L., W.M., B.X., Z.Z., F.L.)
- Department of Biology, Southern University of Science and Technology, Shenzhen, China (B.X.)
| | - Xianzhong Xiao
- Department of Pathophysiology, Xiangya School of Medicine, Central South University, Changsha, Hunan, China (X.X.)
| | - Zhiguang Zhou
- From the Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, National Clinical Research Center for Metabolic Diseases, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China (Q.Z., J.H., Y.W., H.L., W.M., B.X., Z.Z., F.L.)
| | - Feng Liu
- From the Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, National Clinical Research Center for Metabolic Diseases, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China (Q.Z., J.H., Y.W., H.L., W.M., B.X., Z.Z., F.L.)
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23
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Intracellular Signaling in Key Pathways Is Induced by Treatment with Ultrasound and Microbubbles in a Leukemia Cell Line, but Not in Healthy Peripheral Blood Mononuclear Cells. Pharmaceutics 2019; 11:pharmaceutics11070319. [PMID: 31284599 PMCID: PMC6680714 DOI: 10.3390/pharmaceutics11070319] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 07/03/2019] [Accepted: 07/04/2019] [Indexed: 12/21/2022] Open
Abstract
Treatment with ultrasound and microbubbles (sonoporation) to enhance therapeutic efficacy in cancer therapy is rapidly expanding, but there is still very little consensus as to why it works. Despite the original assumption that pore formation in the cell membrane is responsible for increased uptake of drugs, the molecular mechanisms behind this phenomenon are largely unknown. We treated cancer cells (MOLM-13) and healthy peripheral blood mononuclear cells (PBMCs) with ultrasound at three acoustic intensities (74, 501, 2079 mW/cm2) ± microbubbles. We subsequently monitored the intracellular response of a number of key signaling pathways using flow cytometry or western blotting 5 min, 30 min and 2 h post-treatment. This was complemented by studies on uptake of a cell impermeable dye (calcein) and investigations of cell viability (cell count, Hoechst staining and colony forming assay). Ultrasound + microbubbles resulted in both early changes (p38 (Arcsinh ratio at high ultrasound + microbubbles: +0.5), ERK1/2 (+0.7), CREB (+1.3), STAT3 (+0.7) and AKT (+0.5)) and late changes (ribosomal protein S6 (Arcsinh ratio at low ultrasound: +0.6) and eIF2α in protein phosphorylation). Observed changes in protein phosphorylation corresponded to changes in sonoporation efficiency and in viability, predominantly in cancer cells. Sonoporation induced protein phosphorylation in healthy cells was pronounced (p38 (+0.03), ERK1/2 (−0.03), CREB (+0.0), STAT3 (−0.1) and AKT (+0.04) and S6 (+0.2)). This supports the hypothesis that sonoporation may enhance therapeutic efficacy of cancer treatment, without causing damage to healthy cells.
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24
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Qu L, Pan C, He SM, Lang B, Gao GD, Wang XL, Wang Y. The Ras Superfamily of Small GTPases in Non-neoplastic Cerebral Diseases. Front Mol Neurosci 2019; 12:121. [PMID: 31213978 PMCID: PMC6555388 DOI: 10.3389/fnmol.2019.00121] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 04/25/2019] [Indexed: 12/22/2022] Open
Abstract
The small GTPases from the Ras superfamily play crucial roles in basic cellular processes during practically the entire process of neurodevelopment, including neurogenesis, differentiation, gene expression, membrane and protein traffic, vesicular trafficking, and synaptic plasticity. Small GTPases are key signal transducing enzymes that link extracellular cues to the neuronal responses required for the construction of neuronal networks, as well as for synaptic function and plasticity. Different subfamilies of small GTPases have been linked to a number of non-neoplastic cerebral diseases such as Alzheimer’s disease (AD), Parkinson’s disease (PD), intellectual disability, epilepsy, drug addiction, Huntington’s disease (HD), amyotrophic lateral sclerosis (ALS) and a large number of idiopathic cerebral diseases. Here, we attempted to make a clearer illustration of the relationship between Ras superfamily GTPases and non-neoplastic cerebral diseases, as well as their roles in the neural system. In future studies, potential treatments for non-neoplastic cerebral diseases which are based on small GTPase related signaling pathways should be explored further. In this paper, we review all the available literature in support of this possibility.
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Affiliation(s)
- Liang Qu
- Department of Neurosurgery, Tangdu Hospital, Air Force Military Medical University, Xi'an, China
| | - Chao Pan
- Beijing Institute of Biotechnology, Beijing, China
| | - Shi-Ming He
- Department of Neurosurgery, Tangdu Hospital, Air Force Military Medical University, Xi'an, China.,Department of Neurosurgery, Xi'an International Medical Center, Xi'an, China
| | - Bing Lang
- The School of Medicine, Medical Sciences and Nutrition, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom.,Department of Psychiatry, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Guo-Dong Gao
- Department of Neurosurgery, Tangdu Hospital, Air Force Military Medical University, Xi'an, China
| | - Xue-Lian Wang
- Department of Neurosurgery, Tangdu Hospital, Air Force Military Medical University, Xi'an, China
| | - Yuan Wang
- Department of Neurosurgery, Tangdu Hospital, Air Force Military Medical University, Xi'an, China
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25
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Phosphothreonine Lyase Promotes p65 Degradation in a Mitogen-Activated Protein Kinase/Mitogen- and Stress-Activated Protein Kinase 1-Dependent Manner. Infect Immun 2018; 87:IAI.00508-18. [PMID: 30396897 DOI: 10.1128/iai.00508-18] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 09/06/2018] [Indexed: 12/12/2022] Open
Abstract
Bacterial phosphothreonine lyases have been identified to be type III secretion system (T3SS) effectors that irreversibly dephosphorylate host mitogen-activated protein kinase (MAPK) signaling to promote infection. However, the effects of phosphothreonine lyase on nuclear factor κB (NF-κB) signaling remain largely unknown. In this study, we detected significant phosphothreonine lyase-dependent p65 degradation during Edwardsiella piscicida infection in macrophages, and this degradative effect was blocked by the protease inhibitor MG132. Further analysis revealed that phosphothreonine lyase promotes the dephosphorylation and ubiquitination of p65 by inhibiting the phosphorylation of mitogen- and stress-activated protein kinase-1 (MSK1) and by inhibiting the phosphorylation of extracellular signal-related kinase 1/2 (ERK1/2), p38α, and c-Jun N-terminal kinase (JNK). Moreover, we revealed that the catalytic active site of phosphothreonine lyase plays a critical role in regulating the MAPK-MSK1-p65 signaling axis. Collectively, the mechanism described here expands our understanding of the pathogenic effector in not only regulating MAPK signaling but also regulating p65. These findings uncover a new mechanism by which pathogenic bacteria overcome host innate immunity to promote pathogenesis.
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26
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Perspectives of RAS and RHEB GTPase Signaling Pathways in Regenerating Brain Neurons. Int J Mol Sci 2018; 19:ijms19124052. [PMID: 30558189 PMCID: PMC6321366 DOI: 10.3390/ijms19124052] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 12/05/2018] [Accepted: 12/13/2018] [Indexed: 12/29/2022] Open
Abstract
Cellular activation of RAS GTPases into the GTP-binding “ON” state is a key switch for regulating brain functions. Molecular protein structural elements of rat sarcoma (RAS) and RAS homolog protein enriched in brain (RHEB) GTPases involved in this switch are discussed including their subcellular membrane localization for triggering specific signaling pathways resulting in regulation of synaptic connectivity, axonal growth, differentiation, migration, cytoskeletal dynamics, neural protection, and apoptosis. A beneficial role of neuronal H-RAS activity is suggested from cellular and animal models of neurodegenerative diseases. Recent experiments on optogenetic regulation offer insights into the spatiotemporal aspects controlling RAS/mitogen activated protein kinase (MAPK) or phosphoinositide-3 kinase (PI3K) pathways. As optogenetic manipulation of cellular signaling in deep brain regions critically requires penetration of light through large distances of absorbing tissue, we discuss magnetic guidance of re-growing axons as a complementary approach. In Parkinson’s disease, dopaminergic neuronal cell bodies degenerate in the substantia nigra. Current human trials of stem cell-derived dopaminergic neurons must take into account the inability of neuronal axons navigating over a large distance from the grafted site into striatal target regions. Grafting dopaminergic precursor neurons directly into the degenerating substantia nigra is discussed as a novel concept aiming to guide axonal growth by activating GTPase signaling through protein-functionalized intracellular magnetic nanoparticles responding to external magnets.
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27
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Yang D, Li S, Gao L, Lv Z, Bing Q, Lv Q, Zheng X, Li R, Zhang Z. Dietary grape seed procyanidin extract protects against lead-induced heart injury in rats involving endoplasmic reticulum stress inhibition and AKT activation. J Nutr Biochem 2018; 62:43-49. [PMID: 30245182 DOI: 10.1016/j.jnutbio.2018.07.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2018] [Revised: 07/19/2018] [Accepted: 07/26/2018] [Indexed: 12/18/2022]
Abstract
To investigate the protective role of grape seed procyanidin extract (GSPE) against lead-induced heart injury and the possible molecular mechanism associated with this event, Wistar rats were orally given GSPE (200 mg/kg) daily with or without lead acetate (PbA) (0.5 g/L) in drinking water for 56 d. GSPE attenuated oxidative stress, heart dysfunction, and lead accumulation in lead-exposed rat hearts. Meanwhile, GSPE inhibited the protein kinase RNA-like endoplasmic reticulum (ER) kinase/eukaryotic initiation factor 2α signaling pathway, and promoted protein kinase B (AKT) and glycogen synthase kinase 3β phosphorylation altered by lead, and regulated lead-activated apoptosis and its related signaling pathway. This study suggests that dietary GSPE ameliorates lead-induced heart injury associated with ER stress inhibition and AKT activation. Dietary GSPE may be a protector against lead-induced heart injury and a novel therapy for lead exposure.
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Affiliation(s)
- Daqian Yang
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, China; Heilongjiang Key Laboratory for Animal Disease Control and Pharmaceutical Development, Northeast Agricultural University, Harbin 150030, China
| | - Siyu Li
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, China; Heilongjiang Key Laboratory for Animal Disease Control and Pharmaceutical Development, Northeast Agricultural University, Harbin 150030, China; Key Laboratory of the Provincial Education Department of Heilongjiang for Common Animal Disease Prevention and Treatment, Northeast Agricultural University, Harbin 150030, China
| | - Li Gao
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, China; Key Laboratory of the Provincial Education Department of Heilongjiang for Common Animal Disease Prevention and Treatment, Northeast Agricultural University, Harbin 150030, China
| | - Zhanjun Lv
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, China; Key Laboratory of the Provincial Education Department of Heilongjiang for Common Animal Disease Prevention and Treatment, Northeast Agricultural University, Harbin 150030, China
| | - Qizheng Bing
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, China; Heilongjiang Key Laboratory for Animal Disease Control and Pharmaceutical Development, Northeast Agricultural University, Harbin 150030, China; Key Laboratory of the Provincial Education Department of Heilongjiang for Common Animal Disease Prevention and Treatment, Northeast Agricultural University, Harbin 150030, China
| | - Qingjie Lv
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, China
| | - Xiaoyan Zheng
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, China
| | - Ruobing Li
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, China
| | - Zhigang Zhang
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, China; Heilongjiang Key Laboratory for Animal Disease Control and Pharmaceutical Development, Northeast Agricultural University, Harbin 150030, China; Key Laboratory of the Provincial Education Department of Heilongjiang for Common Animal Disease Prevention and Treatment, Northeast Agricultural University, Harbin 150030, China.
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28
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Abstract
The mechanistic target of rapamycin (mTOR) is an important signaling hub that integrates environmental information regarding energy availability and stimulates anabolic molecular processes and cell growth. Abnormalities in this pathway have been identified in several syndromes in which autism spectrum disorder (ASD) is highly prevalent. Several studies have investigated mTOR signaling in developmental and neuronal processes that, when dysregulated, could contribute to the development of ASD. Although many potential mechanisms still remain to be fully understood, these associations are of great interest because of the clinical availability of mTOR inhibitors. Clinical trials evaluating the efficacy of mTOR inhibitors to improve neurodevelopmental outcomes have been initiated.
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Affiliation(s)
- Kellen D. Winden
- F.M. Kirby Neurobiology Center, Translational Neuroscience Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Darius Ebrahimi-Fakhari
- F.M. Kirby Neurobiology Center, Translational Neuroscience Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Mustafa Sahin
- F.M. Kirby Neurobiology Center, Translational Neuroscience Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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29
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Nakhaei-Rad S, Haghighi F, Nouri P, Rezaei Adariani S, Lissy J, Kazemein Jasemi NS, Dvorsky R, Ahmadian MR. Structural fingerprints, interactions, and signaling networks of RAS family proteins beyond RAS isoforms. Crit Rev Biochem Mol Biol 2018; 53:130-156. [PMID: 29457927 DOI: 10.1080/10409238.2018.1431605] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Saeideh Nakhaei-Rad
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Fereshteh Haghighi
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Parivash Nouri
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Soheila Rezaei Adariani
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Jana Lissy
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Neda S Kazemein Jasemi
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Radovan Dvorsky
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Mohammad Reza Ahmadian
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
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30
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Takahashi K, Nagai T, Chiba S, Nakayama K, Mizuno K. Glucose deprivation induces primary cilium formation through mTORC1 inactivation. J Cell Sci 2018; 131:jcs.208769. [PMID: 29180513 DOI: 10.1242/jcs.208769] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 11/20/2017] [Indexed: 01/14/2023] Open
Abstract
Primary cilia are antenna-like sensory organelles extending from the surface of many cell types that play critical roles in tissue development and homeostasis. Here, we examined the effect of nutrient status on primary cilium formation. Glucose deprivation significantly increased the number of ciliated cells under both serum-fed and -starved conditions. Glucose deprivation-induced ciliogenesis was suppressed by overexpression of Rheb, an activator of the mammalian target of rapamycin complex-1 (mTORC1). Inactivating mTORC1 by rapamycin treatment or Raptor knockdown significantly promoted ciliogenesis. These results indicate that glucose deprivation promotes primary cilium formation through mTORC1 inactivation. Rapamycin treatment did not promote autophagy or degradation of OFD1, a negative regulator of ciliogenesis. In contrast, rapamycin treatment increased the level of the p27KIP1 (also known as CDKN1B) cyclin-dependent kinase inhibitor, and rapamycin-induced ciliogenesis was abrogated in p27KIP1-depleted cells. These results indicate that mTORC1 inactivation induces ciliogenesis through p27KIP1 upregulation, but not through autophagy. By contrast, glucose deprivation or rapamycin treatment shortened the cilium length. Thus, glucose deprivation and subsequent inactivation of mTORC1 play dual roles in ciliogenesis: triggering primary cilium formation and shortening cilium length.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Kengo Takahashi
- Department of Biomolecular Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Tomoaki Nagai
- Department of Biomolecular Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Shuhei Chiba
- Department of Genetic Disease Research, Osaka City University, Graduate School of Medicine, Osaka 545-8585, Japan
| | - Keiko Nakayama
- Department of Cell Proliferation, United Center for Advanced Research and Translational Medicine, Graduate School of Medicine, Tohoku University, Sendai, Miyagi 980-8575, Japan
| | - Kensaku Mizuno
- Department of Biomolecular Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan
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31
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Hetz C, Papa FR. The Unfolded Protein Response and Cell Fate Control. Mol Cell 2018; 69:169-181. [DOI: 10.1016/j.molcel.2017.06.017] [Citation(s) in RCA: 744] [Impact Index Per Article: 124.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 06/08/2017] [Accepted: 06/15/2017] [Indexed: 12/12/2022]
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32
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Liu H, Kurtoglu M, León-Annicchiarico CL, Munoz-Pinedo C, Barredo J, Leclerc G, Merchan J, Liu X, Lampidis TJ. Combining 2-deoxy-D-glucose with fenofibrate leads to tumor cell death mediated by simultaneous induction of energy and ER stress. Oncotarget 2017; 7:36461-36473. [PMID: 27183907 PMCID: PMC5095013 DOI: 10.18632/oncotarget.9263] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 04/16/2016] [Indexed: 11/25/2022] Open
Abstract
Unregulated growth and replication as well as an abnormal microenvironment, leads to elevated levels of stress which is a common trait of cancer. By inducing both energy and endoplasmic reticulum (ER) stress, 2-Deoxy-glucose (2-DG) is particularly well-suited to take advantage of the therapeutic window that heightened stress in tumors provides. Under hypoxia, blocking glycolysis with 2-DG leads to significant lowering of ATP resulting in energy stress and cell death in numerous carcinoma cell types. In contrast, under normoxia, 2-DG at a low-concentration is not toxic in most carcinomas tested, but induces growth inhibition, which is primarily due to ER stress. Here we find a synergistic toxic effect in several tumor cell lines in vitro combining 2-DG with fenofibrate (FF), a drug that has been safely used for over 40 years to lower cholesterol in patients. This combination induces much greater energy stress than either agent alone, as measured by ATP reduction, increased p-AMPK and downregulation of mTOR. Inhibition of mTOR results in blockage of GRP78 a critical component of the unfolded protein response which we speculate leads to greater ER stress as observed by increased p-eIF2α. Moreover, to avoid an insulin response and adsorption by the liver, 2-DG is delivered by slow-release pump yielding significant anti-tumor control when combined with FF. Our results provide promise for developing this combination clinically and others that combine 2-DG with agents that act synergistically to selectively increase energy and ER stress to a level that is toxic to numerous tumor cell types.
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Affiliation(s)
- Huaping Liu
- Department of Cell Biology, University of Miami, Miller School of Medicine and Sylvester Comprehensive Cancer Center, Miami, FL, USA
| | | | - Clara Lucia León-Annicchiarico
- Cell Death Regulation Group, Bellvitage Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain
| | - Cristina Munoz-Pinedo
- Cell Death Regulation Group, Bellvitage Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain
| | - Julio Barredo
- Department of Pediatrics, University of Miami, Miller School of Medicine and Sylvester Comprehensive Cancer Center, Miami, FL, USA
| | - Guy Leclerc
- Department of Pediatrics, University of Miami, Miller School of Medicine and Sylvester Comprehensive Cancer Center, Miami, FL, USA
| | - Jaime Merchan
- Department of Medicine, University of Miami, Miller School of Medicine and Sylvester Comprehensive Cancer Center, Miami, FL, USA
| | - Xiongfei Liu
- Department of Cell Biology, University of Miami, Miller School of Medicine and Sylvester Comprehensive Cancer Center, Miami, FL, USA
| | - Theodore J Lampidis
- Department of Cell Biology, University of Miami, Miller School of Medicine and Sylvester Comprehensive Cancer Center, Miami, FL, USA
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33
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Li S, Li J, Zhao Y, Zhang Q, Wang Q. Nutrient sensing signaling integrates nutrient metabolism and intestinal immunity in grass carp, Ctenopharyngodon idellus after prolonged starvation. FISH & SHELLFISH IMMUNOLOGY 2017; 71:50-57. [PMID: 28964867 DOI: 10.1016/j.fsi.2017.09.050] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 09/13/2017] [Accepted: 09/17/2017] [Indexed: 06/07/2023]
Abstract
Starvation has been shown to affect growth and nutrient metabolism in fish; however, little information about the nutrient sensing signaling and mucosal adaptive immunity in fish was known. In the present study, grass carp was starved for 8weeks to simulate the natural aquaculture practice in Hubei during winter. The histology of liver was significantly affected with decreased expression of tight junction proteins including claudin-3, claudin-b and ZO-1. Muscle gene expression was also affected, with decreased expression of muscle growth promoting factors such as Myogenin, MyoD, Myf5, and increased expression of muscle degradation factors, such as CathepsinD. In addition, mucosal adaptive immunity was also significantly affected, with decreased expression of antibodies including IgZ and IgM in gut. Along with these changes was the inhibition of several nutrient sensing signaling including MAPK and TOR signaling, which leads to the inhibition of the synthesis of protein including immunoglobulin. The increased phosphorylation of eIF2α not only inhibited the translation, but also resulted in the decreased expression of IkB and increased expression of NF-<kappa>B, with the activation of pro-inflammatory genes including IL8 and TNF<alpha>.
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Affiliation(s)
- Shan Li
- College of Fisheries, Hubei Provincial Engineering Laboratory for Pond Aquaculture, Huazhong Agricultural University, No. 1, Shizishan Street, Hongshan District, Wuhan 430070, Hubei Province, China
| | - Jiabo Li
- College of Fisheries, Hubei Provincial Engineering Laboratory for Pond Aquaculture, Huazhong Agricultural University, No. 1, Shizishan Street, Hongshan District, Wuhan 430070, Hubei Province, China
| | - Yongliang Zhao
- College of Fisheries, Hubei Provincial Engineering Laboratory for Pond Aquaculture, Huazhong Agricultural University, No. 1, Shizishan Street, Hongshan District, Wuhan 430070, Hubei Province, China
| | - Qin Zhang
- Key Laboratory of Marine Biotechnology of Guangxi, Guangxi Institute of Oceanology, Beihai 536000, China
| | - Qingchao Wang
- College of Fisheries, Hubei Provincial Engineering Laboratory for Pond Aquaculture, Huazhong Agricultural University, No. 1, Shizishan Street, Hongshan District, Wuhan 430070, Hubei Province, China.
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mTOR inhibitors activate PERK signaling and favor viability of gastrointestinal neuroendocrine cell lines. Oncotarget 2017; 8:20974-20987. [PMID: 28423496 PMCID: PMC5400559 DOI: 10.18632/oncotarget.15469] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 02/06/2017] [Indexed: 02/06/2023] Open
Abstract
mTOR and Unfolded Protein Response (UPR) are two signaling pathways frequently activated in cancer cells. The mTOR pathway has been shown to be up-regulated in most gastroenteropancreatic neuroendocrine tumors. In contrast, little is known about the UPR status in neoplastic neuroendocrine cells. However, these hormone-producing cells are likely to present distinctive adaptations of this pathway, as other secretory cells. We therefore analyzed the status of the three axes of UPR and their relation to mTOR pathway in two gastrointestinal neuroendocrine tumors (GI-NET) cell lines STC-1 and GluTag. At baseline, pharmacological inducers activate the three arms of UPR: PERK, ATF6 and IRE1. Although hypoxia stimulates the PERK, ATF6 and IRE-1 pathways in both cell lines, glucose depletion activates UPR only in STC-1 cell line. Strikingly, P-p70S6K1 increases concomitantly to P-PERK and BiP in response to thapsigargin treatment, glucose depletion or hypoxia. We found that different mTOR inhibitors activate the PERK signaling pathway. To confirm that mTOR inhibition modulates PERK activation, we inhibited PERK and showed that it decreased cell viability when associated to mTOR inhibition, indicating that mTOR drives a PERK-dependent survival pathway. In conclusion, in GI-NET cell lines, UPR signaling is functional and PERK arm is induced by mTOR inhibition. These observations open up new perspectives for therapeutic strategies: the crosstalk between mTOR and UPR might contribute to the resistance to mTOR inhibitors and could be targeted by mTOR and PERK inhibitors in combination therapy.
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Potheraveedu VN, Schöpel M, Stoll R, Heumann R. Rheb in neuronal degeneration, regeneration, and connectivity. Biol Chem 2017; 398:589-606. [PMID: 28212107 DOI: 10.1515/hsz-2016-0312] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Accepted: 02/02/2017] [Indexed: 01/31/2023]
Abstract
The small GTPase Rheb was originally detected as an immediate early response protein whose expression was induced by NMDA-dependent synaptic activity in the brain. Rheb's activity is highly regulated by its GTPase activating protein (GAP), the tuberous sclerosis complex protein, which stimulates the conversion from the active, GTP-loaded into the inactive, GDP-loaded conformation. Rheb has been established as an evolutionarily conserved molecular switch protein regulating cellular growth, cell volume, cell cycle, autophagy, and amino acid uptake. The subcellular localization of Rheb and its interacting proteins critically regulate its activity and function. In stem cells, constitutive activation of Rheb enhances differentiation at the expense of self-renewal partially explaining the adverse effects of deregulated Rheb in the mammalian brain. In the context of various cellular stress conditions such as oxidative stress, ER-stress, death factor signaling, and cellular aging, Rheb activation surprisingly enhances rather than prevents cellular degeneration. This review addresses cell type- and cell state-specific function(s) of Rheb and mainly focuses on neurons and their surrounding glial cells. Mechanisms will be discussed in the context of therapy that interferes with Rheb's activity using the antibiotic rapamycin or low molecular weight compounds.
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Affiliation(s)
- Veena Nambiar Potheraveedu
- Molecular Neurobiochemistry, Faculty of Chemistry and Biochemistry, Ruhr University of Bochum, Universitätstr. 150, D-44780 Bochum
| | - Miriam Schöpel
- Biomolecular NMR, Ruhr University of Bochum, D-44780 Bochum
| | - Raphael Stoll
- Biomolecular NMR, Ruhr University of Bochum, D-44780 Bochum
| | - Rolf Heumann
- Molecular Neurobiochemistry, Faculty of Chemistry and Biochemistry, Ruhr University of Bochum, Universitätstr. 150, D-44780 Bochum
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Hino O, Kobayashi T. Mourning Dr. Alfred G. Knudson: the two-hit hypothesis, tumor suppressor genes, and the tuberous sclerosis complex. Cancer Sci 2017; 108:5-11. [PMID: 27862655 PMCID: PMC5276834 DOI: 10.1111/cas.13116] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 11/02/2016] [Accepted: 11/05/2016] [Indexed: 12/16/2022] Open
Abstract
On July 10, 2016, Alfred G. Knudson, Jr., MD, PhD, a leader in cancer research, died at the age of 93 years. We deeply mourn his loss. Knudson's two-hit hypothesis, published in 1971, has been fundamental for understanding tumor suppressor genes and familial tumor-predisposing syndromes. To understand the molecular mechanism of two-hit-initiated tumorigenesis, Knudson used an animal model of a dominantly inherited tumor, the Eker rat. From the molecular identification of Tsc2 germline mutations, the Eker rat became a model for tuberous sclerosis complex (TSC), a familial tumor-predisposing syndrome. Animal models, including the fly, have greatly contributed to TSC research. Because the product of the TSC2/Tsc2 gene (tuberin) together with hamartin, the product of another TSC gene (TSC1/Tsc1), suppresses mammalian/mechanistic target of rapamycin complex 1 (mTORC1), rapalogs have been used as therapeutic drugs for TSC. Although significant activity of these drugs has been reported, there are still problems such as recurrence of residual tumors and adverse effects. Recent studies indicate that there are mTORC1-independent signaling pathways downstream of hamartin/tuberin, which may represent new therapeutic targets. The establishment of cellular models, such as pluripotent stem cells with TSC2/Tsc2 gene mutations, will facilitate the understanding of new aspects of TSC pathogenesis and the development of novel treatment options. In this review, we look back at the history of Knudson and animal models of TSC and introduce recent progress in TSC research.
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Affiliation(s)
- Okio Hino
- Department of Pathology and Oncology, Juntendo University Faculty of Medicine, Tokyo, Japan.,Department of Molecular Pathogenesis, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Toshiyuki Kobayashi
- Department of Pathology and Oncology, Juntendo University Faculty of Medicine, Tokyo, Japan.,Department of Molecular Pathogenesis, Juntendo University Graduate School of Medicine, Tokyo, Japan
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Shahani N, Huang WC, Varnum M, Page DT, Subramaniam S. Forebrain depletion of Rheb GTPase elicits spatial memory deficits in mice. Neurobiol Aging 2016; 50:134-143. [PMID: 27960107 DOI: 10.1016/j.neurobiolaging.2016.11.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 10/20/2016] [Accepted: 11/12/2016] [Indexed: 12/19/2022]
Abstract
The precise molecular and cellular events responsible for age-dependent cognitive dysfunctions remain unclear. We report that Rheb (ras homolog enriched in brain) GTPase, an activator of mammalian target of rapamycin (mTOR), regulates memory functions in mice. Conditional depletion of Rheb selectively in the forebrain of mice obtained from crossing Rhebf/f and CamKIICre results in spontaneous signs of age-related memory loss, that is, spatial memory deficits (T-maze, Morris water maze) without affecting locomotor (open-field test), anxiety-like (elevated plus maze), or contextual fear conditioning functions. Partial depletion of Rheb in forebrain was sufficient to elicit memory defects with little effect on the neuronal size, cortical thickness, or mammalian target of rapamycin activity. Rheb depletion, however, increased the levels of beta-site amyloid precursor protein cleaving enzyme 1 (BACE1), a protein elevated in aging and Alzheimer's disease. Overall, our study demonstrates that forebrain Rheb promotes aging-associated cognitive defects. Thus, molecular understanding of Rheb pathway in brain may provide new therapeutic targets for aging and/or Alzheimer's disease-associated memory deficits.
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Affiliation(s)
- Neelam Shahani
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL, USA
| | - Wen-Chin Huang
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL, USA
| | - Megan Varnum
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL, USA
| | - Damon T Page
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL, USA
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Minard AY, Wong MKL, Chaudhuri R, Tan SX, Humphrey SJ, Parker BL, Yang JY, Laybutt DR, Cooney GJ, Coster ACF, Stöckli J, James DE. Hyperactivation of the Insulin Signaling Pathway Improves Intracellular Proteostasis by Coordinately Up-regulating the Proteostatic Machinery in Adipocytes. J Biol Chem 2016; 291:25629-25640. [PMID: 27738101 DOI: 10.1074/jbc.m116.741140] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 10/11/2016] [Indexed: 01/25/2023] Open
Abstract
Hyperinsulinemia, which is associated with aging and metabolic disease, may lead to defective protein homeostasis (proteostasis) due to hyperactivation of insulin-sensitive pathways such as protein synthesis. We investigated the effect of chronic hyperinsulinemia on proteostasis by generating a time-resolved map of insulin-regulated protein turnover in adipocytes using metabolic pulse-chase labeling and high resolution mass spectrometry. Hyperinsulinemia increased the synthesis of nearly half of all detected proteins and did not affect protein degradation despite suppressing autophagy. Unexpectedly, this marked elevation in protein synthesis was accompanied by enhanced protein stability and folding and not by markers of proteostasis stress such as protein carbonylation and aggregation. The improvement in proteostasis was attributed to a coordinate up-regulation of proteins in the global proteostasis network, including ribosomal, proteasomal, chaperone, and endoplasmic reticulum/mitochondrial unfolded protein response proteins. We conclude that defects associated with hyperactivation of the insulin signaling pathway are unlikely attributed to defective proteostasis because up-regulation of protein synthesis by insulin is accompanied by up-regulation of proteostatic machinery.
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Affiliation(s)
- Annabel Y Minard
- From The Garvan Institute of Medical Research, Sydney, New South Wales 2010, Australia.,Charles Perkins Centre, School of Life Environmental Sciences
| | - Martin K L Wong
- From The Garvan Institute of Medical Research, Sydney, New South Wales 2010, Australia.,Charles Perkins Centre, School of Life Environmental Sciences.,School of Physics
| | - Rima Chaudhuri
- Charles Perkins Centre, School of Life Environmental Sciences
| | - Shi-Xiong Tan
- From The Garvan Institute of Medical Research, Sydney, New South Wales 2010, Australia
| | - Sean J Humphrey
- Charles Perkins Centre, School of Life Environmental Sciences
| | | | | | - D Ross Laybutt
- From The Garvan Institute of Medical Research, Sydney, New South Wales 2010, Australia
| | | | - Adelle C F Coster
- Department of Applied Mathematics, School of Mathematics and Statistics, University of New South Wales, Sydney, New South Wales 2052, Australia
| | | | - David E James
- Charles Perkins Centre, School of Life Environmental Sciences, .,School of Medicine, University of Sydney, Sydney, New South Wales 2006, Australia, and
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Roohi A, Hojjat-Farsangi M. Recent advances in targeting mTOR signaling pathway using small molecule inhibitors. J Drug Target 2016; 25:189-201. [PMID: 27632356 DOI: 10.1080/1061186x.2016.1236112] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Targeted-based cancer therapy (TBCT) or personalized medicine is one of the main treatment modalities for cancer that has been developed to decrease the undesirable effects of chemotherapy. Targeted therapy inhibits the growth of tumor cells by interrupting with particular molecules required for tumorigenesis and proliferation of tumor cells rather than interfering with dividing normal cells. Therefore, targeted therapies are anticipated to be more efficient than former tumor treatment agents with minimal side effects on non-tumor cells. Small molecule inhibitors (SMIs) are currently one of the most investigated anti-tumor agents of TBCT. These small organic agents target several vital molecules involved in cell biological processes and induce target cells apoptosis and necrosis. Mechanistic (mammalian) target of rapamycin (mTOR) complexes (mTORC1/2) control different intracellular processes, including growth, proliferation, angiogenesis and metabolism. Signaling pathways, in which mTOR complexes are involved in are usually dysregulated in various tumors and have been shown to be ideal targets for SMIs. Currently, different mTOR-SMIs are in the clinic for the treatment of cancer patients, and several others are in preclinical or clinical settings. In this review, we summarize recent advances in developing different mTOR inhibitors, which are currently in preclinical and clinical investigations or have been approved for cancer treatment.
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Affiliation(s)
- Azam Roohi
- a Department of Immunology, School of Public Health , Tehran University of Medical Sciences , Tehran , Iran
| | - Mohammad Hojjat-Farsangi
- b Department of Oncology-Pathology, Immune and Gene therapy Lab , Cancer Center Karolinska (CCK), Karolinska University Hospital Solna and Karolinska Institute , Stockholm , Sweden.,c Department of Immunology, School of Medicine , Bushehr University of Medical Sciences , Bushehr , Iran
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40
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Moore M, Gossmann N, Dietz KJ. Redox Regulation of Cytosolic Translation in Plants. TRENDS IN PLANT SCIENCE 2016; 21:388-397. [PMID: 26706442 DOI: 10.1016/j.tplants.2015.11.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 10/31/2015] [Accepted: 11/05/2015] [Indexed: 05/19/2023]
Abstract
Control of protein homeostasis is crucial for environmental acclimation of plants. In this context, translational control is receiving increasing attention, particularly since post-translational modifications of the translational apparatus allow very fast and highly effective control of protein synthesis. Reduction and oxidation (redox) reactions decisively control translation by modifying initiation, elongation, and termination of translation. This opinion article compiles information on the redox sensitivity of cytosolic translation factors and the significance of redox regulation as a key modulator of translation for efficient acclimation to changing environmental conditions.
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Affiliation(s)
- Marten Moore
- Biochemistry and Physiology of Plants, Bielefeld University, 33501 Bielefeld, Germany
| | - Nikolaj Gossmann
- Biochemistry and Physiology of Plants, Bielefeld University, 33501 Bielefeld, Germany
| | - Karl-Josef Dietz
- Biochemistry and Physiology of Plants, Bielefeld University, 33501 Bielefeld, Germany.
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Abstract
Stress induced by accumulation of misfolded proteins in the endoplasmic reticulum is observed in many physiological and pathological conditions. To cope with endoplasmic reticulum stress, cells activate the unfolded protein response, a dynamic signalling network that orchestrates the recovery of homeostasis or triggers apoptosis, depending on the level of damage. Here we provide an overview of recent insights into the mechanisms that cells employ to maintain proteostasis and how the unfolded protein response determines cell fate under endoplasmic reticulum stress.
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