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Siegmund SE, Al-Obaidy KI, Tsai HK, Idrees MT, Akgul M, Acosta AM, Hirsch MS. Concordance of MTOR Pathway Mutations and the Diagnosis of Renal Low-Grade Oncocytic Tumor (LOT). Int J Surg Pathol 2024; 32:316-330. [PMID: 37357748 DOI: 10.1177/10668969231178032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/27/2023]
Abstract
The differential diagnosis for oncocytic renal tumors spans the spectrum from benign entities to more aggressive renal cell carcinomas (RCC). Recent work has characterized a provisional renal oncocytic neoplasm, namely the low-grade oncocytic tumor (LOT), which demonstrates overlapping morphologic features with oncocytoma and chromophobe RCC, but also has a unique immunoprofile (ie, diffusely positive for KRT7, negative for KIT) and a high rate (80% to 100%) of mTOR pathway gene alterations. Given the diagnostic overlap among oncocytic tumors, we looked for concordance between mTOR pathway mutations and LOT. Thirty low-grade renal oncocytic neoplasms underwent histologic review and immunohistochemistry for KRT7 and KIT. Tumors were classified as "determinate" (eg, LOT) for tumors with solid, nested or vaguely tubular growth and diffuse KRT7 staining and negative KIT, or "indeterminate" if the morphology and/or immunostains did not fully support a definitive LOT diagnosis. Next-generation sequencing was performed without any knowledge of the diagnoses, and identified mTOR pathway mutations in 80% (12/15) of the determinate tumors, compared with 7% (1/15) in the indeterminate group. One determinate tumor was reclassified as papillary RCC (MTOR mutation negative) and 6 indeterminate tumors were confirmed to be oncocytoma (N = 4), clear cell RCC or papillary RCC with reverse polarity, respectively. Overall, integration of morphology, immunohistochemistry, and molecular data enabled a final definitive diagnosis for 70% of tumors (21 of the total 30), with a high concordance (93%) for LOT specifically in the determinate group; the remaining 9 tumors (30%) were classified as renal oncocytic neoplasm, not otherwise specified.
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Affiliation(s)
- Stephanie E Siegmund
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Khaleel I Al-Obaidy
- Department of Pathology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Harrison K Tsai
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
- Center for Advanced Molecular Diagnostics, Brigham and Women's Hospital, Boston, MA, USA
| | - Muhammad T Idrees
- Department of Pathology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Mahmut Akgul
- Department of Pathology, Albany Medical Center, Albany, NY, USA
| | - Andres M Acosta
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Michelle S Hirsch
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
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Yang Z, Yu Z, Xiao B. Coordinated Regulation of Myelination by Growth Factor and Amino-acid Signaling Pathways. Neurosci Bull 2023; 39:453-465. [PMID: 36352321 PMCID: PMC10043148 DOI: 10.1007/s12264-022-00967-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Accepted: 06/27/2022] [Indexed: 11/11/2022] Open
Abstract
Myelin-forming oligodendrocytes in the central nervous system (CNS) and Schwann cells in the peripheral nervous system (PNS) are essential for structural and functional homeostasis of nervous tissue. Albeit with certain similarities, the regulation of CNS and PNS myelination is executed differently. Recent advances highlight the coordinated regulation of oligodendrocyte myelination by amino-acid sensing and growth factor signaling pathways. In this review, we discuss novel insights into the understanding of differential regulation of oligodendrocyte and Schwann cell biology in CNS and PNS myelination, with particular focus on the roles of growth factor-stimulated RHEB-mTORC1 and GATOR2-mediated amino-acid sensing/signaling pathways. We also discuss recent progress on the metabolic regulation of oligodendrocytes and Schwann cells and the impact of their dysfunction on neuronal function and disease.
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Affiliation(s)
- Zhiwen Yang
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518000, China
| | - Zongyan Yu
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518000, China.
| | - Bo Xiao
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518000, China.
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Pham LT, Peng H, Ueno M, Kohno S, Kasada A, Hosomichi K, Sato T, Kurayoshi K, Kobayashi M, Tadokoro Y, Kasahara A, Shoulkamy MI, Xiao B, Worley PF, Takahashi C, Tajima A, Hirao A. RHEB is a potential therapeutic target in T cell acute lymphoblastic leukemia. Biochem Biophys Res Commun 2022; 621:74-79. [PMID: 35810594 DOI: 10.1016/j.bbrc.2022.06.089] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 06/26/2022] [Accepted: 06/27/2022] [Indexed: 11/02/2022]
Abstract
T cell acute lymphoblastic leukemia (T-ALL) is an aggressive malignancy of immature T lymphocytes. Although various therapeutic approaches have been developed, refractoriness of chemotherapy and relapse cause a poor prognosis of the disease and further therapeutic strategies are required. Here, we report that Ras homolog enriched in brain (RHEB), a critical regulator of mTOR complex 1 activity, is a potential target for T-ALL therapy. In this study, we established an sgRNA library that comprehensively targeted mTOR upstream and downstream pathways, including autophagy. CRISPR/Cas9 dropout screening revealed critical roles of mTOR-related molecules in T-ALL cell survival. Among the regulators, we focused on RHEB because we previously found that it is dispensable for normal hematopoiesis in mice. Transcriptome and metabolic analyses revealed that RHEB deficiency suppressed de novo nucleotide biosynthesis, leading to human T-ALL cell death. Importantly, RHEB deficiency suppressed tumor growth in both mouse and xenograft models. Our data provide a potential strategy for efficient therapy of T-ALL by RHEB-specific inhibition.
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Affiliation(s)
- Loc Thi Pham
- Division of Molecular Genetics, Cancer and Stem Cell Research Program, Cancer Research Institute, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan
| | - Hui Peng
- Division of Molecular Genetics, Cancer and Stem Cell Research Program, Cancer Research Institute, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan
| | - Masaya Ueno
- Division of Molecular Genetics, Cancer and Stem Cell Research Program, Cancer Research Institute, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan; WPI Nano Life Science Institute (WPI-Nano LSI), Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan
| | - Susumu Kohno
- Division of Oncology and Molecular Biology, Cancer Research Institute, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan
| | - Atuso Kasada
- Division of Molecular Genetics, Cancer and Stem Cell Research Program, Cancer Research Institute, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan
| | - Kazuyoshi Hosomichi
- Department of Bioinformatics and Genomics, Graduate School of Advanced Preventive Medical Sciences, Kanazawa University, 13-1 Takara-machi, Kanazawa, Ishikawa, 920-8640, Japan
| | - Takehiro Sato
- Department of Bioinformatics and Genomics, Graduate School of Advanced Preventive Medical Sciences, Kanazawa University, 13-1 Takara-machi, Kanazawa, Ishikawa, 920-8640, Japan
| | - Kenta Kurayoshi
- Division of Molecular Genetics, Cancer and Stem Cell Research Program, Cancer Research Institute, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan
| | - Masahiko Kobayashi
- Division of Molecular Genetics, Cancer and Stem Cell Research Program, Cancer Research Institute, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan
| | - Yuko Tadokoro
- Division of Molecular Genetics, Cancer and Stem Cell Research Program, Cancer Research Institute, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan; WPI Nano Life Science Institute (WPI-Nano LSI), Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan
| | - Atsuko Kasahara
- Division of Molecular Genetics, Cancer and Stem Cell Research Program, Cancer Research Institute, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan; WPI Nano Life Science Institute (WPI-Nano LSI), Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan; Institute for Frontier Science Initiative, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan
| | - Mahmoud I Shoulkamy
- Division of Molecular Genetics, Cancer and Stem Cell Research Program, Cancer Research Institute, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan; WPI Nano Life Science Institute (WPI-Nano LSI), Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan; Zoology Department, Faculty of Science, Minia University, El-Minia, 61519, Egypt
| | - Bo Xiao
- Department of Biology, School of Life Sciences, Brain Research Center, Southern University of Science and Technology, Shenzhen Key Laboratory of Gene Regulation and Systems Biology, Shenzhen, 518055, PR China
| | - Paul F Worley
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Chiaki Takahashi
- Division of Oncology and Molecular Biology, Cancer Research Institute, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan
| | - Atsushi Tajima
- Department of Bioinformatics and Genomics, Graduate School of Advanced Preventive Medical Sciences, Kanazawa University, 13-1 Takara-machi, Kanazawa, Ishikawa, 920-8640, Japan
| | - Atsushi Hirao
- Division of Molecular Genetics, Cancer and Stem Cell Research Program, Cancer Research Institute, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan; WPI Nano Life Science Institute (WPI-Nano LSI), Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan.
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Gupta S, Kumar M, Chaudhuri S, Kumar A. The non-canonical nuclear functions of key players of the PI3K-AKT-MTOR pathway. J Cell Physiol 2022; 237:3181-3204. [PMID: 35616326 DOI: 10.1002/jcp.30782] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 04/05/2022] [Accepted: 05/02/2022] [Indexed: 12/29/2022]
Abstract
The PI3K-AKT-MTOR signal transduction pathway is one of the essential signalling cascades within the cell due to its involvement in many vital functions. The pathway initiates with the recruitment of phosphatidylinositol-3 kinases (PI3Ks) onto the plasma membrane, generating phosphatidylinositol-3,4,5-triphosphate [PtdIns(3,4,5)P3 ] and subsequently activating AKT. Being the central node of the PI3K network, AKT activates the mechanistic target of rapamycin kinase complex 1 (MTORC1) via Tuberous sclerosis complex 2 inhibition in the cytoplasm. Although the cytoplasmic role of the pathway has been widely explored for decades, we now know that most of the effector molecules of the PI3K axis diverge from the canonical route and translocate to other cell organelles including the nucleus. The presence of phosphoinositides (PtdIns) inside the nucleus itself indicates the existence of a nuclear PI3K signalling. The nuclear localization of these signaling components is evident in regulating many nuclear processes like DNA replication, transcription, DNA repair, maintenance of genomic integrity, chromatin architecture, and cell cycle control. Here, our review intends to present a comprehensive overview of the nuclear functions of the PI3K-AKT-MTOR signaling biomolecules.
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Affiliation(s)
- Sakshi Gupta
- Department of Molecular Reproduction, Development & Genetics, Indian Institute of Science, Bangalore, Karnataka, India
| | - Mukund Kumar
- Department of Molecular Reproduction, Development & Genetics, Indian Institute of Science, Bangalore, Karnataka, India
| | - Soumi Chaudhuri
- Department of Molecular Reproduction, Development & Genetics, Indian Institute of Science, Bangalore, Karnataka, India
| | - Arun Kumar
- Department of Molecular Reproduction, Development & Genetics, Indian Institute of Science, Bangalore, Karnataka, India
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Araki M, Yoshimoto K, Ohta M, Katada T, Kontani K. Development of a versatile HPLC-based method to evaluate the activation status of small GTPases. J Biol Chem 2021; 297:101428. [PMID: 34801548 DOI: 10.1016/j.jbc.2021.101428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 11/01/2021] [Accepted: 11/04/2021] [Indexed: 11/21/2022] Open
Abstract
Small GTPases cycle between an inactive GDP-bound and an active GTP-bound state to control various cellular events, such as cell proliferation, cytoskeleton organization, and membrane trafficking. Clarifying the guanine nucleotide-bound states of small GTPases is vital for understanding the regulation of small GTPase functions and the subsequent cellular responses. Although several methods have been developed to analyze small GTPase activities, our knowledge of the activities for many small GTPases is limited, partly because of the lack of versatile methods to estimate small GTPase activity without unique probes and specialized equipment. In the present study, we developed a versatile and straightforward HPLC-based assay to analyze the activation status of small GTPases by directly quantifying the amounts of guanine nucleotides bound to them. This assay was validated by analyzing the RAS-subfamily GTPases, including HRAS, which showed that the ratios of GTP-bound forms were comparable with those obtained in previous studies. Furthermore, we applied this assay to the investigation of psychiatric disorder-associated mutations of RHEB (RHEB/P37L and RHEB/S68P), revealing that both mutations cause an increase in the ratio of the GTP-bound form in cells. Mechanistically, loss of sensitivity to TSC2 (a GTPase-activating protein for RHEB) for RHEB/P37L, as well as both decreased sensitivity to TSC2 and accelerated guanine-nucleotide exchange for RHEB/S68P, is involved in the increase of their GTP-bound forms, respectively. In summary, the HPLC-based assay developed in this study provides a valuable tool for analyzing small GTPases for which the activities and regulatory mechanisms are less well understood.
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Xu L, Zhang L, Zhang X, Li G, Wang Y, Dong J, Wang H, Hu Z, Cao X, Zhang S, Shi F. HDAC6 Negatively Regulates miR-155-5p Expression to Elicit Proliferation by Targeting RHEB in Microvascular Endothelial Cells under Mechanical Unloading. Int J Mol Sci 2021; 22:10527. [PMID: 34638868 DOI: 10.3390/ijms221910527] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Revised: 09/22/2021] [Accepted: 09/26/2021] [Indexed: 12/20/2022] Open
Abstract
Mechanical unloading contributes to significant cardiovascular deconditioning. Endothelial dysfunction in the sites of microcirculation may be one of the causes of the cardiovascular degeneration induced by unloading, but the detailed mechanism is still unclear. Here, we first demonstrated that mechanical unloading inhibited brain microvascular endothelial cell proliferation and downregulated histone deacetylase 6 (HDAC6) expression. Furthermore, HDAC6 promoted microvascular endothelial cell proliferation and attenuated the inhibition of proliferation caused by clinorotation unloading. To comprehensively identify microRNAs (miRNAs) that are regulated by HDAC6, we analyzed differential miRNA expression in microvascular endothelial cells after transfection with HDAC6 siRNA and selected miR-155-5p, which was the miRNA with the most significantly increased expression. The ectopic expression of miR-155-5p inhibited microvascular endothelial cell proliferation and directly downregulated Ras homolog enriched in brain (RHEB) expression. Moreover, RHEB expression was downregulated under mechanical unloading and was essential for the miR-155-5p-mediated promotion of microvascular endothelial cell proliferation. Taken together, these results are the first to elucidate the role of HDAC6 in unloading-induced cell growth inhibition through the miR-155-5p/RHEB axis, suggesting that the HDAC6/miR-155-5p/RHEB pathway is a specific target for the preventative treatment of cardiovascular deconditioning.
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Shams R, Ito Y, Miyatake H. Evaluation of the Binding Kinetics of RHEB with mTORC1 by In-Cell and In Vitro Assays. Int J Mol Sci 2021; 22:ijms22168766. [PMID: 34445471 PMCID: PMC8395731 DOI: 10.3390/ijms22168766] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 08/04/2021] [Accepted: 08/13/2021] [Indexed: 11/16/2022] Open
Abstract
The mammalian/mechanistic target of rapamycin complex 1 (mTORC1) is activated by the small G-protein, Ras homolog enriched in brain (RHEB–GTPase). On lysosome, RHEB activates mTORC1 by binding the domains of N-heat, M-heat, and the focal adhesion targeting (FAT) domain, which allosterically regulates ATP binding in the active site for further phosphorylation. The crucial role of RHEB in regulating growth and survival through mTORC1 makes it a targetable site for anti-cancer therapeutics. However, the binding kinetics of RHEB to mTORC1 is still unknown at the molecular level. Therefore, we studied the kinetics by in vitro and in-cell protein–protein interaction (PPI) assays. To this end, we used the split-luciferase system (NanoBiT®) for in-cell studies and prepared proteins for the in vitro measurements. Consequently, we demonstrated that RHEB binds to the whole mTOR both in the presence or absence of GTPγS, with five-fold weaker affinity in the presence of GTPγS. In addition, RHEB bound to the truncated mTOR fragments of N-heat domain (∆N, aa 60–167) or M-heat domain (∆M, aa 967–1023) with the same affinity in the absence of GTP. The reconstructed binding site of RHEB, ∆N-FAT-M, however, bound to RHEB with the same affinity as ∆N-M, indicating that the FAT domain (∆FAT, aa 1240–1360) is dispensable for RHEB binding. Furthermore, RHEB bound to the truncated kinase domain (∆ATP, aa 2148–2300) with higher affinity than to ∆N-FAT-M. In conclusion, RHEB engages two different binding sites of mTOR, ∆N-FAT-M and ∆ATP, with higher affinity for ∆ATP, which likely regulates the kinase activity of mTOR through multiple different biding modes.
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Affiliation(s)
- Raef Shams
- Emergent Bioengineering Materials Research Team, RIKEN Center for Emergent Matter Science, RIKEN, Wako 351-0198, Saitama, Japan; (R.S.); (Y.I.)
- Department of Life Science, Graduate School of Science and Engineering, Saitama University, Saitama City 338-8570, Saitama, Japan
| | - Yoshihiro Ito
- Emergent Bioengineering Materials Research Team, RIKEN Center for Emergent Matter Science, RIKEN, Wako 351-0198, Saitama, Japan; (R.S.); (Y.I.)
- Nano Medical Engineering Laboratory, RIKEN Cluster for Pioneering Research, RIKEN, Wako 351-0198, Saitama, Japan
| | - Hideyuki Miyatake
- Department of Life Science, Graduate School of Science and Engineering, Saitama University, Saitama City 338-8570, Saitama, Japan
- Nano Medical Engineering Laboratory, RIKEN Cluster for Pioneering Research, RIKEN, Wako 351-0198, Saitama, Japan
- Correspondence: ; Tel.: +81-48-467-4979
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Tan J, Liu W, Li J, Zhang X, Liu Y, Yuan Y, Song Z. Over-expressed RHEB promotes the progression of pancreatic adenocarcinoma. Life Sci 2021; 277:119462. [PMID: 33831427 DOI: 10.1016/j.lfs.2021.119462] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 03/21/2021] [Accepted: 03/26/2021] [Indexed: 12/31/2022]
Abstract
AIMS Mammalian/mechanistic target of rapamycin (mTOR) is essential in the progression of pancreatic adenocarcinoma (PAAD). But the role of Ras homolog enriched in brain (RHEB), a key activator of mTORC1, is unclear in this disease. This work aims to clarify the function of RHEB in PAAD. MATERIALS AND METHODS A pan-cancer analysis of RHEB was conducted by using data from several public available databases. Immunohistochemical (IHC) staining on a tissue microarray was used to validate the expression of RHEB in PAAD. In vitro experiments were conducted to explore the function of RHEB in the disease. An integrated bioinformatics tools were used to understand the mechanism of RHEB and construct a RHEB-related prognostic signature. KEY FINDINGS RHEB was significantly overexpressed in PAAD and high expression of the gene was associated with poor prognosis. RHEB promoted proliferation, migration and invasion of pancreatic cancer cells. Gene set enrichment analysis (GSEA) showed that RHEB participated in cell cycle progression and WNT signaling pathway. A RHEB-related prognostic signature was developed, and PAAD patients with high risk score had a significantly shorter overall survival. SIGNIFICANCE RHEB was up-regulated in PAAD and might be a useful therapeutic target.
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Affiliation(s)
- Juan Tan
- Department of Pathology, the Third Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Waner Liu
- Xiangya Medical School, Central South University, Changsha, Hunan, China
| | - Jie Li
- Department of Information Science and Engineering, Hunan University of Chinese Medicine, Changsha, Hunan, China
| | - Xi Zhang
- Department of Oncology, the Third Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Yang Liu
- Department of Pathology, the Third Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Yuan Yuan
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA; Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, China
| | - Zewen Song
- Department of Oncology, the Third Xiangya Hospital of Central South University, Changsha, Hunan, China.
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Abstract
Mitochondria sustain various essential functions at synaptic terminals. Synaptic mitochondria deficits have been implicated in early Alzheimer disease (AD) pathophysiology. Mitophagy, a selective autophagy for removal of damaged mitochondria, plays a key role in mitochondrial quality control in neurons. However, fundamental questions remain unanswered as to whether mitophagy regulates synaptic mitochondrial integrity and whether AD-associated early deficits in synaptic mitochondria are attributed to mitophagy failure. We have recently revealed that the integrity of synaptic mitochondria is maintained by a coordination of RHEB-mediated mitophagy with dynein- and SNAPIN-driven retrograde transport. We demonstrate that increased mitophagy initiation, coupled with defective retrograde transport, triggers mitophagy stress at AD synapses. Excitingly, SNAPIN-enhanced retrograde transport reduces synaptic mitophagy stress and ameliorates mitochondrial deficits, thereby counteracting synaptic damage in AD mouse brains. Therefore, our study provides new mechanistic insights into how mitophagy facilitates synaptic mitochondrial maintenance and how mitophagy failure exacerbates AD-linked mitochondrial defects and synaptic degeneration. Abbreviation: AD: Alzheimer disease; Aβ: amyloid-β; APP: amyloid beta precursor protein; CCCP: carbonyl cyanide m-chlorophenylhydrazone; LE: late endosome; Δψm, mitochondrial membrane potential; RHEB: Ras homolog enriched in brain; RNAi: RNA interference; shRNA: small hairpin RNA; Tg: transgenic.
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Affiliation(s)
- Sinsuk Han
- Department of Cell Biology and Neuroscience, Division of Life Science, School of Arts and Sciences, Rutgers, The State University of New Jersey , Piscataway, NJ, USA
| | - Yu Young Jeong
- Department of Cell Biology and Neuroscience, Division of Life Science, School of Arts and Sciences, Rutgers, The State University of New Jersey , Piscataway, NJ, USA
| | - Preethi Sheshadri
- Department of Cell Biology and Neuroscience, Division of Life Science, School of Arts and Sciences, Rutgers, The State University of New Jersey , Piscataway, NJ, USA
| | - Qian Cai
- Department of Cell Biology and Neuroscience, Division of Life Science, School of Arts and Sciences, Rutgers, The State University of New Jersey , Piscataway, NJ, USA
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Chen R, Mao L, Shi R, Wang W, Cheng J. circRNA MYLK Accelerates Cervical Cancer via Up-Regulation of RHEB and Activation of mTOR Signaling. Cancer Manag Res 2020; 12:3611-3621. [PMID: 32547198 PMCID: PMC7245433 DOI: 10.2147/cmar.s238172] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 03/18/2020] [Indexed: 12/16/2022] Open
Abstract
Background Growing evidence directly suggested that circular RNAs (circRNAs) are crucial contributors in the course of cervical cancer (CC) onset and progression. Nevertheless, a large number of circRNAs have not been fully addressed in their function and underlying mechanisms during CC etiology. Purpose Our study focused on the function of circRNA MYLK (myosin light chain kinase), one novel tumor-related circRNA, in CC cell behaviors. Methods Firstly, we evaluated the expression profile of circMYLK in CC cells and in normal Ect1/E6E7 cell line. Moreover, the accurate function of circMYLK in CC cells was assessed via colony formation, CCK-8, EdU, and TUNEL assay. The association among circRNAs, miRNA, and target mRNAs was predicated by bioinformatics methods and validated in mechanical assays. Results We disclosed that circMYLK was up-regulated in CC cell lines and acted as a sponge of miR-1301-3p. Besides, downstream miR-1301-3p was capable of reversing circMYLK-mediated CC cell growth and apoptosis. Furthermore, we validated that circMYLK bound to miR-1301-3p as a sponge to upregulate RHEB (Ras homolog, mTORC1 binding) expression. As annotated in prior works, RHEB was responsible for mTOR signaling transduction. Therefore, we investigated whether circMYLK functioned its tumor-facilitating impact in CC through a RHEB-dependent mTOR signaling activation. Conclusion It was unveiled that circMYLK sponged miR-1301-3p to promote RHEB expression, which resulted in mTOR signaling activation and CC cell malignant growth.
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Affiliation(s)
- Rui Chen
- Department of Gynecology, East Hospital Affiliated to Tongji University, Shanghai 200012, People's Republic of China
| | - Luning Mao
- Department of Pathology, Basic Medical College, Fudan University, Shanghai 200032, People's Republic of China
| | - Rui Shi
- Department of Gynecology, East Hospital Affiliated to Tongji University, Shanghai 200012, People's Republic of China
| | - Wenjing Wang
- Department of Gynecology, East Hospital Affiliated to Tongji University, Shanghai 200012, People's Republic of China
| | - Jingxin Cheng
- Department of Gynecology, East Hospital Affiliated to Tongji University, Shanghai 200012, People's Republic of China
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Ashraf S, Kim BJ, Park S, Park H, Lee SH. RHEB gene therapy maintains the chondrogenic characteristics and protects cartilage tissue from degenerative damage during experimental murine osteoarthritis. Osteoarthritis Cartilage 2019; 27:1508-1517. [PMID: 31229684 DOI: 10.1016/j.joca.2019.05.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 05/20/2019] [Accepted: 05/24/2019] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Osteoarthritis (OA) is characterized by cartilage degeneration resulting from hypertrophic changes in chondrocytes caused by altered gene expression. The involvement of Ras homolog enriched in brain (RHEB) in OA regulation is unclear. METHODS Human knee articular cartilage samples - were analyzed for structural and biological changes by histology, immunohistochemistry, real time PCR and western blotting. OA-mouse model developed by surgical destabilization of the medial meniscus (DMM) were treated with adenovirus harboring Rheb gene to analyze onset and progression of OA. Histological scoring, immunohistochemistry, and TUNEL assay was performed to assess cartilage damage across the entire joint. RESULTS Human and mouse OA cartilage is degenerated and has markedly reduced levels of RHEB. Human OA-degenerated chondrocytes (DC) exhibited a fibroblastic phenotype and 80 % of degenerative cartilage were senescent, with higher levels of reactive oxygen species (ROS). Gene expression analysis of DC revealed almost no COL2A1 expression and reduced SOX9 and RHEB expression. Transient transfection of RHEB rescued the DC phenotype and reduced senescence and ROS levels markedly. RHEB overexpression also increased COL2A1 and SOX9 expression. In an OA-mouse model, the Rheb protein level decreased as the severity of OA increased. Ectopic expression of Rheb using adenovirus in mouse-OA cartilage suppressed surgically-induced OA pathogenesis accompanied by modulation of Adamts5, Mmp 13, Col 10, and Col2a1 expression. Rheb induction significantly reduced apoptosis in OA-cartilage. CONCLUSION RHEB plays an important role in maintaining the chondrogenic characteristics of chondrocytes, and has potential in preventing progression of OA in the destabilize the medial meniscus (DMM) mouse model of OA.
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Affiliation(s)
- S Ashraf
- School of Integrative Engineering, Chung-Ang University, Seoul, Republic of Korea
| | - B J Kim
- Department of Medical Biotechnology, Dongguk University, Seoul, Republic of Korea
| | - S Park
- Department of Biomedical Science, CHA University, Seoul, Republic of Korea
| | - H Park
- School of Integrative Engineering, Chung-Ang University, Seoul, Republic of Korea.
| | - S-H Lee
- Department of Medical Biotechnology, Dongguk University, Seoul, Republic of Korea.
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Tian Y, Shen L, Li F, Yang J, Wan X, Ouyang M. Silencing of RHEB inhibits cell proliferation and promotes apoptosis in colorectal cancer cells via inhibition of the mTOR signaling pathway. J Cell Physiol 2019; 235:442-453. [PMID: 31332784 DOI: 10.1002/jcp.28984] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Revised: 03/28/2019] [Accepted: 05/20/2019] [Indexed: 01/10/2023]
Abstract
Colorectal cancer (CRC) is commonly known as one of the most prominent reasons for cancer-related death in China. Ras homolog enriched in brain (RHEB) and the mammalian target activity of rapamycin (mTOR) signaling pathway were found correlated with CRC, but their specific interaction in CRC was still to be investigated. Therefore, we explored whether RHEB gene silencing affected the cell proliferation, differentiation, and apoptosis by directly targeting the mTOR signaling pathway in cells previously harvested from CRC patients. A microarray analysis was subsequently conducted to investigate the relationship between RHEB and mTOR. Eighty-three adjacent normal tissues and CRC tissues were selected. Immunohistochemistry was carried out to detect the positive expression rates of RHEB and Ki-67 in the CRC tissues. Cells were then transfected with different siRNAs to investigate the potential effects RHEB would have on CRC progression. The expressions of RHEB, 4EBP1, ribosomal protein S6 kinase (p70S6K), proliferating cell nuclear antigen (PCNA), B cell lymphoma 2 (bcl-2), and bcl-2-associated X protein (bax) were determined and then the cell cycle, cell proliferation, and apoptotic rate were also measured. We identified RHEB and mTOR as upregulated genes in CRC. Cells treated with RHEB silencing showed a decreased extent of mTOR, p70S6K, 4EBP1 phosphorylation and expression of RHEB, Ki-67, mTOR, p70S6K, 4EBP1, bcl-2, and PCNA as well as decreased activity of cell proliferation and differentiation; although, the expression of bax was evidently higher. Collectively, our data propose the idea that RHEB gene silencing might repress cell proliferation and differentiation while accelerating apoptosis via inactivating the mTOR signaling pathway.
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Affiliation(s)
- Yuxi Tian
- Department of Oncology, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Liangfang Shen
- Department of Oncology, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Fujun Li
- Department of Gastroenterology, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Junwen Yang
- Department of Gastroenterology, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Xiaoping Wan
- Department of Hepatobiliary Surgery, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Miao Ouyang
- Department of Gastroenterology, Xiangya Hospital, Central South University, Changsha, Hunan, China
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Walton ZE, Patel CH, Brooks RC, Yu Y, Ibrahim-Hashim A, Riddle M, Porcu A, Jiang T, Ecker BL, Tameire F, Koumenis C, Weeraratna AT, Welsh DK, Gillies R, Alwine JC, Zhang L, Powell JD, Dang CV. Acid Suspends the Circadian Clock in Hypoxia through Inhibition of mTOR. Cell 2018; 174:72-87.e32. [PMID: 29861175 PMCID: PMC6398937 DOI: 10.1016/j.cell.2018.05.009] [Citation(s) in RCA: 149] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2017] [Revised: 01/11/2018] [Accepted: 05/02/2018] [Indexed: 12/17/2022]
Abstract
Recent reports indicate that hypoxia influences the circadian clock through the transcriptional activities of hypoxia-inducible factors (HIFs) at clock genes. Unexpectedly, we uncover a profound disruption of the circadian clock and diurnal transcriptome when hypoxic cells are permitted to acidify to recapitulate the tumor microenvironment. Buffering against acidification or inhibiting lactic acid production fully rescues circadian oscillation. Acidification of several human and murine cell lines, as well as primary murine T cells, suppresses mechanistic target of rapamycin complex 1 (mTORC1) signaling, a key regulator of translation in response to metabolic status. We find that acid drives peripheral redistribution of normally perinuclear lysosomes away from perinuclear RHEB, thereby inhibiting the activity of lysosome-bound mTOR. Restoring mTORC1 signaling and the translation it governs rescues clock oscillation. Our findings thus reveal a model in which acid produced during the cellular metabolic response to hypoxia suppresses the circadian clock through diminished translation of clock constituents.
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Affiliation(s)
- Zandra E Walton
- Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - Chirag H Patel
- Bloomberg-Kimmel Institute for Cancer Immunotherapy, Sidney-Kimmel Comprehensive Cancer Research Center, Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA
| | - Rebekah C Brooks
- Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Yongjun Yu
- Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Arig Ibrahim-Hashim
- Department of Cancer Physiology and Department of Radiology, H. Lee Moffitt Cancer Center, Tampa, FL 33612, USA
| | - Malini Riddle
- Department of Psychiatry and Center for Circadian Biology, University of California, San Diego, La Jolla, CA 92093, USA; Veterans Affairs San Diego Healthcare System, San Diego, CA 92161, USA
| | - Alessandra Porcu
- Department of Psychiatry and Center for Circadian Biology, University of California, San Diego, La Jolla, CA 92093, USA; Veterans Affairs San Diego Healthcare System, San Diego, CA 92161, USA
| | | | - Brett L Ecker
- The Wistar Institute, Philadelphia, PA 19104, USA; Department of Surgery, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Feven Tameire
- Department of Radiation Oncology, Perelman University School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Constantinos Koumenis
- Department of Radiation Oncology, Perelman University School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | | | - David K Welsh
- Department of Psychiatry and Center for Circadian Biology, University of California, San Diego, La Jolla, CA 92093, USA; Veterans Affairs San Diego Healthcare System, San Diego, CA 92161, USA
| | - Robert Gillies
- Department of Cancer Physiology and Department of Radiology, H. Lee Moffitt Cancer Center, Tampa, FL 33612, USA
| | - James C Alwine
- Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Lin Zhang
- Center for Research on Reproduction & Women's Health, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Obstetrics and Gynecology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jonathan D Powell
- Bloomberg-Kimmel Institute for Cancer Immunotherapy, Sidney-Kimmel Comprehensive Cancer Research Center, Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA
| | - Chi V Dang
- Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; The Wistar Institute, Philadelphia, PA 19104, USA; Ludwig Institute for Cancer Research, New York, NY 10017, USA.
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Liu F, Pan Z, Zhang J, Ni J, Wang C, Wang Z, Gu F, Dong W, Zhou W, Liu H. Overexpression of RHEB is associated with metastasis and poor prognosis in hepatocellular carcinoma. Oncol Lett 2018; 15:3838-3845. [PMID: 29467900 DOI: 10.3892/ol.2018.7759] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 08/25/2016] [Indexed: 12/11/2022] Open
Abstract
Aberrant expression of Ras homolog enriched in brain (RHEB) has been observed in a variety of cancer tissues and is closely associated with clinicopathological features. However, the expression profile of RHEB in patients with hepatocellular carcinoma (HCC) and its clinical signature with underlying mechanisms have not been explored thus far. To analyze the association between RHEB expression and clinicopathological features, the RHEB expression levels were determined in the present study using gene microarrays, immunohistochemistry and western blotting in 60 liver cancer tissues and 35 normal liver tissues. Downregulation of RHEB expression in liver cancer cell lines was achieved by RNA interfering technology to explore its biological function in HCC. RHEB expression was high in liver cancer tissues, with an increase of 2.00±0.19-fold compared with normal tissues and of 2.00±0.27-fold compared with adjacent non-cancer tissues. RHEB expression increased along with the clinical staging of HCC, and the overall survival and mortality of patients were closely correlated to RHEB levels, micro-vascular invasion, hepatitis B virus-DNA titer, tumor differentiation and pathological satellites (P<0.05). After knocking down RHEB in SMMC-7721 cells, the growth of liver cancer cells was significantly reduced. The majority of cells were blocked in S-phase, and their colony-forming and proliferating abilities significantly decreased (P<0.05). In vivo, upon downregulation of RHEB expression, the tumorigenic ability of HCC significantly decreased (P<0.05). These data suggest that RHEB expression is a significant prognostic factor and may be important in HCC cell growth. The present study highlights the importance of RHEB as a novel prognostic marker of HCC.
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Affiliation(s)
- Fuchen Liu
- The Third Department of Hepatic Surgery, Eastern Hepatobiliary Surgery Hospital, Second Military Medical University, Shanghai 200438, P.R. China
| | - Zeya Pan
- The Third Department of Hepatic Surgery, Eastern Hepatobiliary Surgery Hospital, Second Military Medical University, Shanghai 200438, P.R. China
| | - Jinmin Zhang
- The Third Department of Hepatic Surgery, Eastern Hepatobiliary Surgery Hospital, Second Military Medical University, Shanghai 200438, P.R. China
| | - Junsheng Ni
- The Third Department of Hepatic Surgery, Eastern Hepatobiliary Surgery Hospital, Second Military Medical University, Shanghai 200438, P.R. China
| | - Chao Wang
- The Third Department of Hepatic Surgery, Eastern Hepatobiliary Surgery Hospital, Second Military Medical University, Shanghai 200438, P.R. China
| | - Zhenguang Wang
- The Third Department of Hepatic Surgery, Eastern Hepatobiliary Surgery Hospital, Second Military Medical University, Shanghai 200438, P.R. China
| | - Fangming Gu
- The Third Department of Hepatic Surgery, Eastern Hepatobiliary Surgery Hospital, Second Military Medical University, Shanghai 200438, P.R. China
| | - Wei Dong
- The Third Department of Hepatic Surgery, Eastern Hepatobiliary Surgery Hospital, Second Military Medical University, Shanghai 200438, P.R. China
| | - Weiping Zhou
- The Third Department of Hepatic Surgery, Eastern Hepatobiliary Surgery Hospital, Second Military Medical University, Shanghai 200438, P.R. China
| | - Hui Liu
- The Third Department of Hepatic Surgery, Eastern Hepatobiliary Surgery Hospital, Second Military Medical University, Shanghai 200438, P.R. China
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Heard JJ, Phung I, Potes MI, Tamanoi F. An oncogenic mutant of RHEB, RHEB Y35N, exhibits an altered interaction with BRAF resulting in cancer transformation. BMC Cancer 2018; 18:69. [PMID: 29320991 PMCID: PMC5763582 DOI: 10.1186/s12885-017-3938-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Accepted: 12/19/2017] [Indexed: 12/31/2022] Open
Abstract
Background RHEB is a unique member of the RAS superfamily of small GTPases expressed in all tissues and conserved from yeast to humans. Early studies on RHEB indicated a possible RHEB-RAF interaction, but this has not been fully explored. Recent work on cancer genome databases has revealed a reoccurring mutation in RHEB at the Tyr35 position, and a recent study points to the oncogenic potential of this mutant that involves activation of RAF/MEK/ERK signaling. These developments prompted us to reassess the significance of RHEB effect on RAF, and to compare mutant and wild type RHEB. Methods To study RHEB-RAF interaction, and the effect of the Y35N mutation on this interaction, we used transfection, immunoprecipitation, and Western blotting techniques. We generated cell lines stably expressing RHEB WT, RHEB Y35N, and KRAS G12V, and monitored cellular transforming properties through cell proliferation, anchorage independent growth, cell cycle analysis, and foci formation assays. Results We observe a strong interaction between RHEB and BRAF, but not with CRAF. This interaction is dependent on an intact RHEB effector domain and RHEB-GTP loading status. RHEB overexpression decreases RAF activation of the RAF/MEK/ERK pathway and RHEB knockdown results in an increase in RAF/MEK/ERK activation. RHEB Y35N mutation has decreased interaction with BRAF, and RHEB Y35N cells exhibit greater BRAF/CRAF heterodimerization resulting in increased RAF/MEK/ERK signaling. This leads to cancer transformation of RHEB Y35N stably expressing cell lines, similar to KRAS G12 V expressing cell lines. Conclusions RHEB interaction with BRAF is crucial for inhibiting RAF/MEK/ERK signaling. The RHEB Y35N mutant sustains RAF/MEK/ERK signaling due to a decreased interaction with BRAF, leading to increased BRAF/CRAF heterodimerization. RHEB Y35N expressing cells undergo cancer transformation due to decreased interaction between RHEB and BRAF resulting in overactive RAF/MEK/ERK signaling. Taken together with the previously established function of RHEB to activate mTORC1 signaling, it appears that RHEB performs a dual function; one is to suppress the RAF/MEK/ERK signaling and the other is to activate mTORC1 signaling. Electronic supplementary material The online version of this article (10.1186/s12885-017-3938-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jeffrey J Heard
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, 1602 Molecular Sciences Bldg, 609 Charles E. Young Dr. East, Los Angeles, CA, 90095-1489, USA
| | - Ivy Phung
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, 1602 Molecular Sciences Bldg, 609 Charles E. Young Dr. East, Los Angeles, CA, 90095-1489, USA
| | - Mark I Potes
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, 1602 Molecular Sciences Bldg, 609 Charles E. Young Dr. East, Los Angeles, CA, 90095-1489, USA
| | - Fuyuhiko Tamanoi
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, 1602 Molecular Sciences Bldg, 609 Charles E. Young Dr. East, Los Angeles, CA, 90095-1489, USA. .,Institute for Integrated Cell-Material Sciences, Kyoto University, Kyoto, Japan.
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16
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Zhou L, Liu S, Han M, Ma Y, Feng S, Zhao J, Lu H, Yuan X, Cheng J. miR-185 Inhibits Fibrogenic Activation of Hepatic Stellate Cells and Prevents Liver Fibrosis. Mol Ther Nucleic Acids 2017; 10:91-102. [PMID: 29499960 PMCID: PMC5735261 DOI: 10.1016/j.omtn.2017.11.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 11/20/2017] [Accepted: 11/20/2017] [Indexed: 02/07/2023]
Abstract
Recent studies have shown the effect of microRNAs on HSC activation and transformation, which is essential for the pathogenesis of liver fibrosis. In our study, we explored the role of miR-185 in liver fibrosis. Plasma miR-185 was detected in hepatitis B virus-related liver fibrosis patients (S2/3, n = 10) by Illumina HiSeq sequencing, and healthy volunteers were selected (n = 8) as the control group. We found that the plasma miR-185 level in fibrosis patients was significantly downregulated. CCl4-induced fibrosis tissues in mouse livers and TGF-β1-activated HSCs also presented downregulated miR-185 concomitant with an increased expression of RHEB and RICTOR. To explore the correlations, LX-2 cells were transiently transfected with miR-185 mimics. The expression levels of α-SMA, collagen I, and collagen III were decreased as well as RHEB and RICTOR. Inhibition of endogenous miR-185 increased fibrogenic activity. Furthermore, dual-luciferase reporter assays indicated that miR-185 inhibited the expression of RHEB and RICTOR by directly targeting their 3' UTRs. Moreover, silencing RHEB and RICTOR suppressed α-SMA and collagen expression levels. In conclusion, miR-185 prevents liver fibrogenesis by inhibiting HSC activation via inhibition of RHEB and RICTOR. These results provide new insights into the mechanisms behind the anti-fibrotic effect of miR-185.
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Affiliation(s)
- Li Zhou
- Peking University Ditan Teaching Hospital, Beijing 100015, China; Beijing Key Laboratory of Emerging Infectious Diseases, Beijing 100015, China; Institiute of Infectious Diseases, Beijing Ditan Hospital, Capital Medical University, Beijing 100015, China
| | - Shunai Liu
- Beijing Key Laboratory of Emerging Infectious Diseases, Beijing 100015, China; Institiute of Infectious Diseases, Beijing Ditan Hospital, Capital Medical University, Beijing 100015, China
| | - Ming Han
- Peking University Ditan Teaching Hospital, Beijing 100015, China; Beijing Key Laboratory of Emerging Infectious Diseases, Beijing 100015, China; Institiute of Infectious Diseases, Beijing Ditan Hospital, Capital Medical University, Beijing 100015, China
| | - Yanhua Ma
- Peking University Ditan Teaching Hospital, Beijing 100015, China; Beijing Key Laboratory of Emerging Infectious Diseases, Beijing 100015, China
| | - Shenghu Feng
- Peking University Ditan Teaching Hospital, Beijing 100015, China; Beijing Key Laboratory of Emerging Infectious Diseases, Beijing 100015, China
| | - Jing Zhao
- Peking University Ditan Teaching Hospital, Beijing 100015, China; Beijing Key Laboratory of Emerging Infectious Diseases, Beijing 100015, China
| | - Hongping Lu
- Beijing Key Laboratory of Emerging Infectious Diseases, Beijing 100015, China; Institiute of Infectious Diseases, Beijing Ditan Hospital, Capital Medical University, Beijing 100015, China
| | - Xiaoxue Yuan
- Beijing Key Laboratory of Emerging Infectious Diseases, Beijing 100015, China; Institiute of Infectious Diseases, Beijing Ditan Hospital, Capital Medical University, Beijing 100015, China
| | - Jun Cheng
- Peking University Ditan Teaching Hospital, Beijing 100015, China; Beijing Key Laboratory of Emerging Infectious Diseases, Beijing 100015, China; Institiute of Infectious Diseases, Beijing Ditan Hospital, Capital Medical University, Beijing 100015, China.
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Tatebe H, Shiozaki K. Evolutionary Conservation of the Components in the TOR Signaling Pathways. Biomolecules 2017; 7:E77. [PMID: 29104218 DOI: 10.3390/biom7040077] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 10/26/2017] [Accepted: 10/27/2017] [Indexed: 01/08/2023] Open
Abstract
Target of rapamycin (TOR) is an evolutionarily conserved protein kinase that controls multiple cellular processes upon various intracellular and extracellular stimuli. Since its first discovery, extensive studies have been conducted both in yeast and animal species including humans. Those studies have revealed that TOR forms two structurally and physiologically distinct protein complexes; TOR complex 1 (TORC1) is ubiquitous among eukaryotes including animals, yeast, protozoa, and plants, while TOR complex 2 (TORC2) is conserved in diverse eukaryotic species other than plants. The studies have also identified two crucial regulators of mammalian TORC1 (mTORC1), Ras homolog enriched in brain (RHEB) and RAG GTPases. Of these, RAG regulates TORC1 in yeast as well and is conserved among eukaryotes with the green algae and land plants as apparent exceptions. RHEB is present in various eukaryotes but sporadically missing in multiple taxa. RHEB, in the budding yeast Saccharomyces cerevisiae, appears to be extremely divergent with concomitant loss of its function as a TORC1 regulator. In this review, we summarize the evolutionarily conserved functions of the key regulatory subunits of TORC1 and TORC2, namely RAPTOR, RICTOR, and SIN1. We also delve into the evolutionary conservation of RHEB and RAG and discuss the conserved roles of these GTPases in regulating TORC1.
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Latosinska A, Mokou M, Makridakis M, Mullen W, Zoidakis J, Lygirou V, Frantzi M, Katafigiotis I, Stravodimos K, Hupe MC, Dobrzynski M, Kolch W, Merseburger AS, Mischak H, Roubelakis MG, Vlahou A. Proteomics analysis of bladder cancer invasion: Targeting EIF3D for therapeutic intervention. Oncotarget 2017; 8:69435-55. [PMID: 29050215 DOI: 10.18632/oncotarget.17279] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 04/07/2017] [Indexed: 02/07/2023] Open
Abstract
Patients with advanced bladder cancer have poor outcomes, indicating a need for more efficient therapeutic approaches. This study characterizes proteomic changes underlying bladder cancer invasion aiming for the better understanding of disease pathophysiology and identification of drug targets. High resolution liquid chromatography coupled to tandem mass spectrometry analysis of tissue specimens from patients with non-muscle invasive (NMIBC, stage pTa) and muscle invasive bladder cancer (MIBC, stages pT2+) was conducted. Comparative analysis identified 144 differentially expressed proteins between analyzed groups. These included proteins previously associated with bladder cancer and also additional novel such as PGRMC1, FUCA1, BROX and PSMD12, which were further confirmed by immunohistochemistry. Pathway and interactome analysis predicted strong activation in muscle invasive bladder cancer of pathways associated with protein synthesis e.g. eIF2 and mTOR signaling. Knock-down of eukaryotic translation initiation factor 3 subunit D (EIF3D) (overexpressed in muscle invasive disease) in metastatic T24M bladder cancer cells inhibited cell proliferation, migration, and colony formation in vitro and decreased tumor growth in xenograft models. By contrast, knocking down GTP-binding protein Rheb (which is upstream of EIF3D) recapitulated the effects of EIF3D knockdown in vitro, but not in vivo. Collectively, this study represents a comprehensive analysis of NMIBC and MIBC providing a resource for future studies. The results highlight EIF3D as a potential therapeutic target.
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Ghosh AP, Marshall CB, Coric T, Shim EH, Kirkman R, Ballestas ME, Ikura M, Bjornsti MA, Sudarshan S. Point mutations of the mTOR- RHEB pathway in renal cell carcinoma. Oncotarget 2016; 6:17895-910. [PMID: 26255626 PMCID: PMC4627224 DOI: 10.18632/oncotarget.4963] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 07/03/2015] [Indexed: 01/21/2023] Open
Abstract
Aberrations in the mTOR (mechanistic target of rapamycin) axis are frequently reported in cancer. Using publicly available tumor genome sequencing data, we identified several point mutations in MTOR and its upstream regulator RHEB (Ras homolog enriched in brain) in patients with clear cell renal cell carcinoma (ccRCC), the most common histology of kidney cancer. Interestingly, we found a prominent cluster of hyperactivating mutations in the FAT (FRAP-ATM-TTRAP) domain of mTOR in renal cell carcinoma that led to an increase in both mTORC1 and mTORC2 activities and led to an increased proliferation of cells. Several of the FAT domain mutants demonstrated a decreased binding of DEPTOR (DEP domain containing mTOR-interacting protein), while a subset of these mutations showed altered binding of the negative regulator PRAS40 (proline rich AKT substrate 40). We also identified a recurrent mutation in RHEB in ccRCC patients that leads to an increase in mTORC1 activity. In vitro characterization of this RHEB mutation revealed that this mutant showed considerable resistance to TSC2 (Tuberous Sclerosis 2) GAP (GTPase activating protein) activity, though its interaction with TSC2 remained unaltered. Mutations in the FAT domain of MTOR and in RHEB remained sensitive to rapamycin, though several of these mutations demonstrated residual mTOR kinase activity after treatment with rapamycin at clinically relevant doses. Overall, our data suggests that point mutations in the mTOR pathway may lead to downstream mTOR hyperactivation through multiple different mechanisms to confer a proliferative advantage to a tumor cell.
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Affiliation(s)
- Arindam P Ghosh
- Department of Urology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Christopher B Marshall
- Department of Medical Biophysics, Campbell Family Cancer Research Institute, Princess Margaret Cancer Centre, University of Toronto, Toronto, Canada
| | - Tatjana Coric
- Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Eun-Hee Shim
- Department of Urology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Richard Kirkman
- Department of Urology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Mary E Ballestas
- Department of Pediatrics, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Mitsuhiko Ikura
- Department of Medical Biophysics, Campbell Family Cancer Research Institute, Princess Margaret Cancer Centre, University of Toronto, Toronto, Canada
| | - Mary-Ann Bjornsti
- Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Sunil Sudarshan
- Department of Urology, University of Alabama at Birmingham, Birmingham, Alabama, USA
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Ashraf S, Ahn J, Cha BH, Kim JS, Han I, Park H, Lee SH. RHEB: a potential regulator of chondrocyte phenotype for cartilage tissue regeneration. J Tissue Eng Regen Med 2016; 11:2503-2515. [PMID: 27061379 DOI: 10.1002/term.2148] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 12/14/2015] [Accepted: 12/22/2015] [Indexed: 01/03/2023]
Abstract
As articular cartilage has a limited ability to self-repair, successful cartilage regeneration requires clinical-grade chondrocytes with innate characteristics. However, cartilage regeneration via chondrocyte transplantation is challenging, because chondrocytes lose their innate characteristics during in vitro expansion. Here, we investigated the mechanistic underpinning of the gene Ras homologue enriched in brain (RHEB) in the control of senescence and dedifferentiation through the modulation of oxidative stress in chondrocytes, a hallmark of osteoarthritis. Serial expansion of human chondrocytes led to senescence, dedifferentiation and oxidative stress. RHEB maintained the innate characteristics of chondrocytes by regulating senescence, dedifferentiation and oxidative stress, leading to the upregulation of COL2 expression via SOX9 and the downregulation of p27 expression via MCL1. RHEB also decreased the expression of COL10. RHEB knockdown mimics decreased the expression of SOX9, COL2 and MCL1, while abrogating the suppressive function of RHEB on p27 and COL10 in chondrocytes. RHEB-overexpressing chondrocytes successfully formed cartilage tissue in vitro as well as in vivo, with increased expression of GAG matrix and chondrogenic markers. RHEB induces a distinct gene expression signature that maintained the innate chondrogenic properties over a long period. Therefore, RHEB expression represents a potentially useful mechanism in terms of cartilage tissue regeneration from chondrocytes, by which chondrocyte phenotypic and molecular characteristics can be retained through the modulation of senescence, dedifferentiation and oxidative stress. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- S Ashraf
- Department of Biomedical Science, CHA University, Seoul, Republic of Korea.,School of Integrative Engineering, Chung-Ang University, Seoul, Republic of Korea
| | - J Ahn
- Department of Biomedical Science, CHA University, Seoul, Republic of Korea
| | - B-H Cha
- Department of Biomedical Science, CHA University, Seoul, Republic of Korea
| | - J-S Kim
- Department of Biomedical Science, CHA University, Seoul, Republic of Korea
| | - I Han
- Department of Neurosurgery, CHA University, CHA Bundang Medical Centre, Kyeunggi-do, Republic of Korea
| | - H Park
- School of Integrative Engineering, Chung-Ang University, Seoul, Republic of Korea
| | - S-H Lee
- Department of Biomedical Science, CHA University, Seoul, Republic of Korea
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Wan G, Xie W, Liu Z, Xu W, Lao Y, Huang N, Cui K, Liao M, He J, Jiang Y, Yang BB, Xu H, Xu N, Zhang Y. Hypoxia-induced MIR155 is a potent autophagy inducer by targeting multiple players in the MTOR pathway. Autophagy 2013; 10:70-9. [PMID: 24262949 PMCID: PMC4389881 DOI: 10.4161/auto.26534] [Citation(s) in RCA: 137] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Hypoxia activates autophagy, an evolutionarily conserved cellular catabolic process. Dysfunction in the autophagy pathway has been implicated in an increasing number of human diseases, including cancer. Hypoxia induces upregulation of a specific set of microRNAs (miRNAs) in a variety of cell types. Here, we describe hypoxia-induced MIR155 as a potent inducer of autophagy. Enforced expression of MIR155 increases autophagic activity in human nasopharyngeal cancer and cervical cancer cells. Knocking down endogenous MIR155 inhibits hypoxia-induced autophagy. We demonstrated that MIR155 targets multiple players in MTOR signaling, including RHEB, RICTOR, and RPS6KB2. MIR155 suppresses target-gene expression by directly interacting with their 3′ untranslated regions (UTRs), mutations of the binding sites abolish their MIR155 responsiveness. Furthermore, by downregulating MTOR signaling, MIR155 also attenuates cell proliferation and induces G1/S cell cycle arrest. Collectively, these data present a new role for MIR155 as a key regulator of autophagy via dysregulation of MTOR pathway.
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Affiliation(s)
- Gang Wan
- School of Life Sciences; Tsinghua University; Beijing, China; Key Lab in Healthy Science and Technology; Division of Life Science; Graduate School at Shenzhen; Tsinghua University; Shenzhen, China
| | - Weidong Xie
- Key Lab in Healthy Science and Technology; Division of Life Science; Graduate School at Shenzhen; Tsinghua University; Shenzhen, China
| | - Zhenyan Liu
- School of Pharmacy; Shanghai University of Traditional Chinese Medicine; Shanghai, China
| | - Wei Xu
- School of Life Sciences; Tsinghua University; Beijing, China; Key Lab in Healthy Science and Technology; Division of Life Science; Graduate School at Shenzhen; Tsinghua University; Shenzhen, China
| | - Yuanzhi Lao
- School of Pharmacy; Shanghai University of Traditional Chinese Medicine; Shanghai, China
| | - Nunu Huang
- School of Life Sciences; Tsinghua University; Beijing, China; Key Lab in Healthy Science and Technology; Division of Life Science; Graduate School at Shenzhen; Tsinghua University; Shenzhen, China
| | - Kai Cui
- School of Life Sciences; Tsinghua University; Beijing, China; Key Lab in Healthy Science and Technology; Division of Life Science; Graduate School at Shenzhen; Tsinghua University; Shenzhen, China
| | - Meijian Liao
- School of Life Sciences; Tsinghua University; Beijing, China; Key Lab in Healthy Science and Technology; Division of Life Science; Graduate School at Shenzhen; Tsinghua University; Shenzhen, China
| | - Jie He
- Key Lab in Healthy Science and Technology; Division of Life Science; Graduate School at Shenzhen; Tsinghua University; Shenzhen, China
| | - Yuyang Jiang
- The State Key Laboratory Breeding Base-Shenzhen Key Laboratory of Chemical Biology; Graduate School at Shenzhen; Tsinghua University; Shenzhen, China
| | - Burton B Yang
- Department of Laboratory Medicine and Pathobiology; University of Toronto; Toronto, ON CA
| | - Hongxi Xu
- School of Pharmacy; Shanghai University of Traditional Chinese Medicine; Shanghai, China
| | - Naihan Xu
- Key Lab in Healthy Science and Technology; Division of Life Science; Graduate School at Shenzhen; Tsinghua University; Shenzhen, China
| | - Yaou Zhang
- Key Lab in Healthy Science and Technology; Division of Life Science; Graduate School at Shenzhen; Tsinghua University; Shenzhen, China
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