1
|
Tung TY, Brennan JR. Expectations modulate retrieval interference during ellipsis resolution. Neuropsychologia 2023; 190:108680. [PMID: 37739260 DOI: 10.1016/j.neuropsychologia.2023.108680] [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: 04/20/2023] [Revised: 09/01/2023] [Accepted: 09/07/2023] [Indexed: 09/24/2023]
Abstract
Memory operations during language comprehension are subject to interference: retrieval is harder when items are linguistically similar to each other. We test how such interference effects might be modulated by linguistic expectations. Theories differ in how these factors might interact; we consider three possibilities: (i) predictability determines the need for retrieval, (ii) predictability affects cue-preference during retrieval, or (iii) word predictability moderates the effect of noise in memory during retrieval. We first demonstrate that expectations for a target word modulate retrieval interference in Mandarin noun-phrase ellipsis in an electroencephalography (EEG) experiment. This result obtains in globally ungrammatical sentences - termed "facilitatory interference." Such a pattern is inconsistent with theories that focus only on the need for retrieval. To tease apart cue-preferences from noisy-memory representations, we operationalize the latter using a Transformer neural network language model. Confronting the model with our stimuli reveals an interference effect, consistent with prior work, but that effect does not interact with predictability in contrast to human EEG results. Together, these data are most consistent with the hypothesis that the predictability of target items affects cue-preferences during retrieval.
Collapse
Affiliation(s)
- Tzu-Yun Tung
- Department of Linguistics, University of Michigan, Ann Arbor, MI, USA.
| | | |
Collapse
|
2
|
Wang B, Pei J, Xu S, Liu J, Yu J. System analysis based on glutamine catabolic-related enzymes identifies GPT2 as a novel immunotherapy target for lung adenocarcinoma. Comput Biol Med 2023; 165:107415. [PMID: 37657356 DOI: 10.1016/j.compbiomed.2023.107415] [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: 06/21/2023] [Revised: 07/31/2023] [Accepted: 08/28/2023] [Indexed: 09/03/2023]
Abstract
BACKGROUND In recent years, targeting glutamine metabolism has gained attention as a promising therapeutic approach. Glutamine catabolic-related enzymes play a crucial role in modulating glutamine metabolism and influencing immune responses in the tumor immune microenvironment (TME). However, current literature on the function of glutamine catabolic enzymes in lung adenocarcinoma (LUAD) is limited. METHODS We validated the glutamine dependency of LUAD cells in vitro, followed by transcriptome data to identify differentially expressed genes (DEGs), with transcriptome and single-cell data analysis utilized to explore the role of such genes within the tumor immune microenvironment. We performed employed subcutaneous injection of lewis lung carcinoma cells in C57BL/6 mice to confirm the role of candidate genes in tumor growth and anti-tumor immunity. RESULTS Our study revealed that glutamine is essential for the growth of LUAD cells. Subsequently, we identified four DEGs - glutamate pyruvate transaminase 1 (GPT1), glutamate pyruvate transaminase 2 (GPT2), glutamic-oxaloacetic transaminase 1 (GOT1), and glutamic-oxaloacetic transaminase 2 (GOT2) - in LUAD patients, which were highly expressed in tumor tissue and associated with an immunosuppressive TME. Single-cell sequencing analysis detected high expression levels of GOT1 and GOT2 in immune and stromal cell subpopulations, while GPT1 and GPT2 showed relatively lower expression. Based on the lower immune score and lower expression in immune and stromal cells, we validated the role of GPT2 in vivo for modulating the TME and tumor growth. Inhibition of GPT2 resulted in suppressed tumor growth and increased the expression of CD4 and CD8. Additionally, GPT2 inhibitors induced a stronger antitumor immunity when used in combination with anti-programmed cell death ligand 1. CONCLUSION This study is the first to show the critical role of glutamine catabolic-related enzymes in the TME, and identified GPT2 as a promising therapeutic target for inhibiting tumor growth and improving anti-tumour immune responses for LUAD. Additional studies will be required to define the roles glutamine catabolic-related enzymes play in LUAD.
Collapse
Affiliation(s)
- Bolin Wang
- Lung Cancer Center, West China Hospital, Sichuan University, Chengdu, China; Department of Radiation Oncology and Shandong Provincial Key Laboratory of Radiation Oncology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences Jinan, Shandong, China; Research Unit of Radiation Oncology, Chinese Academy of Medical Sciences, Jinan, Shandong, China
| | - Jinli Pei
- Department of Radiation Oncology and Shandong Provincial Key Laboratory of Radiation Oncology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences Jinan, Shandong, China; Research Unit of Radiation Oncology, Chinese Academy of Medical Sciences, Jinan, Shandong, China
| | - Shengnan Xu
- Department of Radiation Oncology and Shandong Provincial Key Laboratory of Radiation Oncology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences Jinan, Shandong, China; Research Unit of Radiation Oncology, Chinese Academy of Medical Sciences, Jinan, Shandong, China
| | - Jie Liu
- Department of Radiation Oncology and Shandong Provincial Key Laboratory of Radiation Oncology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences Jinan, Shandong, China; Research Unit of Radiation Oncology, Chinese Academy of Medical Sciences, Jinan, Shandong, China.
| | - Jinming Yu
- Department of Radiation Oncology and Shandong Provincial Key Laboratory of Radiation Oncology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences Jinan, Shandong, China; Research Unit of Radiation Oncology, Chinese Academy of Medical Sciences, Jinan, Shandong, China.
| |
Collapse
|
3
|
Li N, Xu X, Liu D, Gao J, Gao Y, Wu X, Sheng H, Li Q, Mi J. The delta subunit of the GABA A receptor is necessary for the GPT2-promoted breast cancer metastasis. Theranostics 2023; 13:1355-1369. [PMID: 36923530 PMCID: PMC10008743 DOI: 10.7150/thno.80544] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [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: 11/06/2022] [Accepted: 02/12/2023] [Indexed: 03/13/2023] Open
Abstract
Objectives: Glutamic pyruvate transaminase (GPT2) catalyzes the reversible transamination between alanine and α-ketoglutarate (α-KG) to generate pyruvate and glutamate during cellular glutamine catabolism. The glutamate could be further converted to γ-aminobutyric acid (GABA). However, the role of GPT2 in tumor metastasis remains unclear. Methods: The wound healing and transwell assays were carried out to analyze breast cancer cell migration and invasion in vitro. Gene ontology analysis was utilized following RNA-sequencing to discover the associated molecule function. The mass spectrometry analysis following phosphoprotein enrichment was performed to discover the associated transcription factors. Most importantly, both the tail vein model and Mammary gland conditional Gpt2-/- spontaneous tumor mouse models were used to evaluate the effect of GPT2 on breast cancer metastasis in vivo. Results: GPT2 overexpression increases the content of GABA and promotes breast cancer metastasis by activating GABAA receptors. The delta subunit GABRD is necessary for the GPT2/GABA-induced breast cancer metastasis in xenograft and transgenic mouse models. Gpt2 knockout reduces the lung metastasis of the genetic Gpt2-/- breast cancer in mice and prolongs the overall survival of tumor burden mice. Mechanistically, GPT2-induced GABAA receptor activation increases Ca2+ influx by turning on its associated calcium channel, and the surged intracellular calcium triggers the PKC-CREB pathway activation. The activated transcription factor CREB accelerates breast cancer metastasis by upregulating metastasis-related gene expressions, such as PODXL, MMP3, and MMP9. Conclusion: In summary, this study demonstrates that GPT2 promotes breast cancer metastasis through up-regulated GABA activation of GABAAR-PKC-CREB signaling, suggesting it is a potential target for breast cancer therapy.
Collapse
Affiliation(s)
- Na Li
- Hongqiao International Institute of Medicine, Tongren Hospital; Basic Medical Institute; Key Laboratory of Cell Differentiation and Apoptosis of the Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine
| | - Xiang Xu
- Hongqiao International Institute of Medicine, Tongren Hospital; Basic Medical Institute; Key Laboratory of Cell Differentiation and Apoptosis of the Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine
- Department of Laboratory Medicine, Shanghai General Hospital Jiading Branch, Shanghai
| | - Dan Liu
- Hongqiao International Institute of Medicine, Tongren Hospital; Basic Medical Institute; Key Laboratory of Cell Differentiation and Apoptosis of the Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine
| | - Jiaxin Gao
- College of Basic Medical Sciences, Dalian Medical University
| | - Ying Gao
- College of Basic Medical Sciences, Dalian Medical University
| | - Xufeng Wu
- Hongqiao International Institute of Medicine, Tongren Hospital; Basic Medical Institute; Key Laboratory of Cell Differentiation and Apoptosis of the Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine
| | - Huiming Sheng
- Department of Clinic Laboratory, Tongren Hospital, Shanghai Jiao Tong University School of Medicine
- ✉ Corresponding authors: Huiming Sheng: ; Qun Li, ; Jun Mi,
| | - Qun Li
- Department of Oncology, Shanghai East Hospital, Tongji University School of Medicine
- ✉ Corresponding authors: Huiming Sheng: ; Qun Li, ; Jun Mi,
| | - Jun Mi
- Hongqiao International Institute of Medicine, Tongren Hospital; Basic Medical Institute; Key Laboratory of Cell Differentiation and Apoptosis of the Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine
- ✉ Corresponding authors: Huiming Sheng: ; Qun Li, ; Jun Mi,
| |
Collapse
|
4
|
Wu J, Miao C, Wang Y, Wang S, Wang Z, Liu Y, Wang X, Wang Z. SPTBN1 abrogates renal clear cell carcinoma progression via glycolysis reprogramming in a GPT2-dependent manner. J Transl Med 2022; 20:603. [PMID: 36527113 PMCID: PMC9756479 DOI: 10.1186/s12967-022-03805-w] [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] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 12/02/2022] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Renal clear cell carcinoma (ccRCC) is the most prevalent tumors worldwide. Discovering effective biomarkers is essential to monitor the prognosis and provide alternative clinical options. SPTBN1 is implicated in various cancerous processes. However, its role in ccRCC remains unelucidated. This study intends to explore the biological function and mechanism of SPTBN1 in ccRCC. METHODS Single-cell and bulk RNA-seq, tissue microarray, real-time quantitative PCR, and western blotting were applied to verify the expression and predictive value of SPTBN1 in ccRCC. Gain or loss of functional ccRCC cell line models were constructed, and in vitro and in vivo assays were performed to elucidate its tumorigenic phenotypes. Actinomycin D experiment, RNA immunoprecipitation (RIP), specific inhibitors, and rescue experiments were carried out to define the molecular mechanisms. RESULTS SPTBN1 was down-regulated in ccRCC and knockdown of SPTBN1 displayed a remarkably oncogenic role both in vitro and in vivo; while overexpressing SPTBN1 reversed this effect. SPTBN1 mediated ccRCC progression via the pathway of glutamate pyruvate transaminase 2 (GPT2)-dependent glycolysis. The expression of GPT2 was significantly negatively correlated with that of SPTBN1. As an RNA binding protein SPTBN1, regulated the mRNA stability of GPT2. CONCLUSION Our research demonstrated that SPTBN1 is significantly down-regulated in ccRCC. SPTBN1 knockdown promotes ccRCC progression via activating GPT2-dependent glycolysis. SPTBN1 may serve as a therapeutic target for the treatment of ccRCC.
Collapse
Affiliation(s)
- Jiajin Wu
- grid.412676.00000 0004 1799 0784Department of Urology, The First Affiliated Hospital of Nanjing Medical University/Jiangsu Province Hospital, No. 300 Guangzhou Road, Nanjing, 210029 China
| | - Chenkui Miao
- grid.412676.00000 0004 1799 0784Department of Urology, The First Affiliated Hospital of Nanjing Medical University/Jiangsu Province Hospital, No. 300 Guangzhou Road, Nanjing, 210029 China
| | - Yuhao Wang
- grid.412676.00000 0004 1799 0784Department of Urology, The First Affiliated Hospital of Nanjing Medical University/Jiangsu Province Hospital, No. 300 Guangzhou Road, Nanjing, 210029 China
| | - Songbo Wang
- grid.412676.00000 0004 1799 0784Department of Urology, The First Affiliated Hospital of Nanjing Medical University/Jiangsu Province Hospital, No. 300 Guangzhou Road, Nanjing, 210029 China
| | - Zhongyuan Wang
- grid.412676.00000 0004 1799 0784Department of Urology, The First Affiliated Hospital of Nanjing Medical University/Jiangsu Province Hospital, No. 300 Guangzhou Road, Nanjing, 210029 China
| | - Yiyang Liu
- grid.412676.00000 0004 1799 0784Department of Urology, The First Affiliated Hospital of Nanjing Medical University/Jiangsu Province Hospital, No. 300 Guangzhou Road, Nanjing, 210029 China
| | - Xiaoyi Wang
- grid.412676.00000 0004 1799 0784Core Facility Center, The First Affiliated Hospital of Nanjing Medical University/Jiangsu Province Hospital, No. 300 Guangzhou Road, Nanjing, 210029 China
| | - Zengjun Wang
- grid.412676.00000 0004 1799 0784Department of Urology, The First Affiliated Hospital of Nanjing Medical University/Jiangsu Province Hospital, No. 300 Guangzhou Road, Nanjing, 210029 China
| |
Collapse
|
5
|
Weng H, Huang F, Yu Z, Chen Z, Prince E, Kang Y, Zhou K, Li W, Hu J, Fu C, Aziz T, Li H, Li J, Yang Y, Han L, Zhang S, Ma Y, Sun M, Wu H, Zhang Z, Wunderlich M, Robinson S, Braas D, Hoeve JT, Zhang B, Marcucci G, Mulloy JC, Zhou K, Tao HF, Deng X, Horne D, Wei M, Huang H, Chen J. The m 6A reader IGF2BP2 regulates glutamine metabolism and represents a therapeutic target in acute myeloid leukemia. Cancer Cell 2022; 40:1566-1582.e10. [PMID: 36306790 PMCID: PMC9772162 DOI: 10.1016/j.ccell.2022.10.004] [Citation(s) in RCA: 54] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Revised: 08/19/2022] [Accepted: 10/05/2022] [Indexed: 02/05/2023]
Abstract
N6-Methyladenosine (m6A) modification and its modulators play critical roles and show promise as therapeutic targets in human cancers, including acute myeloid leukemia (AML). IGF2BP2 was recently reported as an m6A binding protein that enhances mRNA stability and translation. However, its function in AML remains largely elusive. Here we report the oncogenic role and the therapeutic targeting of IGF2BP2 in AML. High expression of IGF2BP2 is observed in AML and associates with unfavorable prognosis. IGF2BP2 promotes AML development and self-renewal of leukemia stem/initiation cells by regulating expression of critical targets (e.g., MYC, GPT2, and SLC1A5) in the glutamine metabolism pathways in an m6A-dependent manner. Inhibiting IGF2BP2 with our recently identified small-molecule compound (CWI1-2) shows promising anti-leukemia effects in vitro and in vivo. Collectively, our results reveal a role of IGF2BP2 and m6A modification in amino acid metabolism and highlight the potential of targeting IGF2BP2 as a promising therapeutic strategy in AML.
Collapse
Affiliation(s)
- Hengyou Weng
- The Fifth Affiliated Hospital, State Key Laboratory of Respiratory Diseases, Guangzhou Laboratory, Guangzhou Medical University, Guangzhou 510005, China
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA
- Bioland Laboratory, Guangzhou 51005, China
| | - Feng Huang
- The Fifth Affiliated Hospital, State Key Laboratory of Respiratory Diseases, Guangzhou Laboratory, Guangzhou Medical University, Guangzhou 510005, China; Bioland Laboratory, Guangzhou 51005, China
| | - Zhaojin Yu
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA; Department of Pharmacology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110122, China
| | - Zhenhua Chen
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA
| | - Emily Prince
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA
| | - Yalin Kang
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou 510060, China
| | - Keren Zhou
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA
| | - Wei Li
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA
| | - Jiacheng Hu
- Bioland Laboratory, Guangzhou 51005, China; Shantou University Medical College, Shantou 515063, China
| | - Chen Fu
- Department of Pharmacology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110122, China
| | - Tursunjan Aziz
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou 510060, China
| | - Hongzhi Li
- Department of Molecular Medicine, Beckman Research Institute of City of Hope, Duarte, CA 91010, USA
| | - Jingwen Li
- Bioland Laboratory, Guangzhou 51005, China
| | - Ying Yang
- The Fifth Affiliated Hospital, State Key Laboratory of Respiratory Diseases, Guangzhou Laboratory, Guangzhou Medical University, Guangzhou 510005, China; Bioland Laboratory, Guangzhou 51005, China
| | - Li Han
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA
| | - Subo Zhang
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou 510060, China
| | - Yuelong Ma
- Department of Molecular Medicine, Beckman Research Institute of City of Hope, Duarte, CA 91010, USA
| | - Mingli Sun
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA; Department of Pharmacology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110122, China
| | - Huizhe Wu
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA; Department of Pharmacology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110122, China
| | - Zheng Zhang
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA
| | - Mark Wunderlich
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Sean Robinson
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA
| | - Daniel Braas
- UCLA Metabolomics Center, Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Johanna Ten Hoeve
- UCLA Metabolomics Center, Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Bin Zhang
- Department of Hematologic Malignancies Translational Science, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA; Gehr Family Center for Leukemia Research & City of Hope Comprehensive Cancer Center, City of Hope, Duarte, CA 91010, USA
| | - Guido Marcucci
- Department of Hematologic Malignancies Translational Science, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA; Gehr Family Center for Leukemia Research & City of Hope Comprehensive Cancer Center, City of Hope, Duarte, CA 91010, USA
| | - James C Mulloy
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Keda Zhou
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, the University of Hong Kong, Hong Kong SAR, China
| | - Hong-Fang Tao
- Department of Hematology, The First Affiliated Hospital of Shantou University Medical College, Shantou 515041, China
| | - Xiaolan Deng
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA
| | - David Horne
- Department of Molecular Medicine, Beckman Research Institute of City of Hope, Duarte, CA 91010, USA
| | - Minjie Wei
- Department of Pharmacology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110122, China
| | - Huilin Huang
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou 510060, China
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA
| | - Jianjun Chen
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA
- Gehr Family Center for Leukemia Research & City of Hope Comprehensive Cancer Center, City of Hope, Duarte, CA 91010, USA
| |
Collapse
|
6
|
Lee J, Kim T, Park J, Park J. Smartphone Sensor-Based Human Motion Characterization with Neural Stochastic Differential Equations and Transformer Model. Sensors (Basel) 2022; 22:7480. [PMID: 36236580 PMCID: PMC9572335 DOI: 10.3390/s22197480] [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] [Figures] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Revised: 09/27/2022] [Accepted: 09/28/2022] [Indexed: 06/16/2023]
Abstract
With many conveniences afforded by advances in smartphone technology, developing advanced data analysis methods for health-related information from smartphone users has become a fast-growing research topic in the healthcare field. Along these lines, this paper addresses smartphone sensor-based characterization of human motions with neural stochastic differential equations (NSDEs) and a Transformer model. NSDEs and modeling via Transformer networks are two of the most prominent deep learning-based modeling approaches, with significant performance yields in many applications. For the problem of modeling dynamical features, stochastic differential equations and deep neural networks are frequently used paradigms in science and engineering, respectively. Combining these two paradigms in one unified framework has drawn significant interest in the deep learning community, and NSDEs are among the leading technologies for combining these efforts. The use of attention has also become a widely adopted strategy in many deep learning applications, and a Transformer is a deep learning model that uses the mechanism of self-attention. This concept of a self-attention based Transformer was originally introduced for tasks of natural language processing (NLP), and due to its excellent performance and versatility, the scope of its applications is rapidly expanding. By utilizing the techniques of neural stochastic differential equations and a Transformer model along with data obtained from smartphone sensors, we present a deep learning method capable of efficiently characterizing human motions. For characterizing human motions, we encode the high-dimensional sequential data from smartphone sensors into latent variables in a low-dimensional latent space. The concept of the latent variable is particularly useful because it can not only carry condensed information concerning motion data, but also learn their low-dimensional representations. More precisely, we use neural stochastic differential equations for modeling transitions of human motion in a latent space, and rely on a Generative Pre-trained Transformer 2 (GPT2)-based Transformer model for approximating the intractable posterior of conditional latent variables. Our experiments show that the proposed method can yield promising results for the problem of characterizing human motion patterns and some related tasks including user identification.
Collapse
|
7
|
Zhang B, Chen Y, Bao L, Luo W. GPT2 Is Induced by Hypoxia-Inducible Factor (HIF)-2 and Promotes Glioblastoma Growth. Cells 2022; 11:2597. [PMID: 36010673 DOI: 10.3390/cells11162597] [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: 07/10/2022] [Revised: 08/12/2022] [Accepted: 08/17/2022] [Indexed: 11/17/2022] Open
Abstract
Hypoxia-inducible factor (HIF) directly activates the transcription of metabolic enzymes in response to hypoxia to reprogram cellular metabolism required for tumor cell proliferation. Through analyzing glutamate-linked aminotransferases, we here identified glutamate pyruvate transaminase 2 (GPT2) as a direct HIF-2 target gene in human glioblastoma (GBM). Hypoxia upregulated GPT2 mRNA and protein levels in GBM cells, which required HIF-2 but not HIF-1. HIF-2 directly bound to the hypoxia response element of the human GPT2 gene, leading to its transcription in hypoxic GBM cells. GPT2 located at the nucleus and mitochondria and reduced α-ketoglutarate levels in GBM cells. Genetic or pharmacological inhibition of GPT2 decreased GBM cell growth and migration under normoxia and hypoxia. Knockout of GPT2 inhibited GBM tumor growth in mice. Collectively, these findings uncover a hypoxia-inducible aminotransferase GPT2 required for GBM progression.
Collapse
|
8
|
Baytas O, Kauer JA, Morrow EM. Loss of mitochondrial enzyme GPT2 causes early neurodegeneration in locus coeruleus. Neurobiol Dis 2022; 173:105831. [PMID: 35908744 PMCID: PMC9669404 DOI: 10.1016/j.nbd.2022.105831] [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] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 07/06/2022] [Accepted: 07/20/2022] [Indexed: 12/02/2022] Open
Abstract
Locus coeruleus (LC) is among the first brain areas to degenerate in Alzheimer’s disease and Parkinson’s disease; however, the underlying causes for the vulnerability of LC neurons are not well defined. Here we report a novel mechanism of degeneration of LC neurons caused by loss of the mitochondrial enzyme glutamate pyruvate transaminase 2 (GPT2). GPT2 Deficiency is a newly-recognized childhood neurometabolic disorder. The GPT2 enzyme regulates cell growth through replenishment of tricarboxylic acid (TCA) cycle intermediates and modulation of amino acid metabolism. In Gpt2-null mice, we observe an early loss of tyrosine hydroxylase (TH)-positive neurons in LC and reduced soma size at postnatal day 18. Gpt2-null LC shows selective positive Fluoro-Jade C staining. Neuron loss is accompanied by selective, prominent microgliosis and astrogliosis in LC. We observe reduced noradrenergic projections to and norepinephrine levels in hippocampus and spinal cord. Whole cell recordings in Gpt2-null LC slices show reduced soma size and abnormal action potentials with altered firing kinetics. Strikingly, we observe early decreases in phosphorylated S6 in Gpt2-null LC, preceding prominent p62 aggregation, increased LC3B-II to LC3B-I ratio, and neuronal loss. These data are consistent with a possible mechanism involving deficiency in protein synthesis and cell growth, associated subsequently with abnormal autophagy and neurodegeneration. As compared to the few genetic animal models with LC degeneration, loss of LC neurons in Gpt2-null mice is developmentally the earliest. Early neuron loss in LC in a model of human neurometabolic disease provides important clues regarding the metabolic vulnerability of LC and may lead to new therapeutic targets.
Collapse
Affiliation(s)
- Ozan Baytas
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI 02912, USA; Center for Translational Neuroscience, Carney Institute for Brain Science and Brown Institute for Translational Science, Brown University, Providence, RI 02912, USA; Neuroscience Graduate Program, Brown University, Providence, RI 02912, USA
| | - Julie A Kauer
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, CA 94035, USA
| | - Eric M Morrow
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI 02912, USA; Center for Translational Neuroscience, Carney Institute for Brain Science and Brown Institute for Translational Science, Brown University, Providence, RI 02912, USA.
| |
Collapse
|
9
|
Martino MR, Gutiérrez-Aguilar M, Yiew NKH, Lutkewitte AJ, Singer JM, McCommis KS, Ferguson D, Liss KHH, Yoshino J, Renkemeyer MK, Smith GI, Cho K, Fletcher JA, Klein S, Patti GJ, Burgess SC, Finck BN. Silencing alanine transaminase 2 in diabetic liver attenuates hyperglycemia by reducing gluconeogenesis from amino acids. Cell Rep 2022; 39:110733. [PMID: 35476997 PMCID: PMC9121396 DOI: 10.1016/j.celrep.2022.110733] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 02/21/2022] [Accepted: 04/02/2022] [Indexed: 12/13/2022] Open
Abstract
Hepatic gluconeogenesis from amino acids contributes significantly to diabetic hyperglycemia, but the molecular mechanisms involved are incompletely understood. Alanine transaminases (ALT1 and ALT2) catalyze the interconversion of alanine and pyruvate, which is required for gluconeogenesis from alanine. We find that ALT2 is overexpressed in the liver of diet-induced obese and db/db mice and that the expression of the gene encoding ALT2 (GPT2) is downregulated following bariatric surgery in people with obesity. The increased hepatic expression of Gpt2 in db/db liver is mediated by activating transcription factor 4, an endoplasmic reticulum stress-activated transcription factor. Hepatocyte-specific knockout of Gpt2 attenuates incorporation of 13C-alanine into newly synthesized glucose by hepatocytes. In vivo Gpt2 knockdown or knockout in liver has no effect on glucose concentrations in lean mice, but Gpt2 suppression alleviates hyperglycemia in db/db mice. These data suggest that ALT2 plays a significant role in hepatic gluconeogenesis from amino acids in diabetes. Martino et al. find that alanine transaminase 2 (ALT2), which is encoded by Gpt2, is increased in liver of mice and people with obesity by activating transcription factor 4. Suppression of Gpt2 expression in obese, but not lean mice, lowers blood glucose by suppressing alanine-mediated gluconeogenesis.
Collapse
Affiliation(s)
- Michael R Martino
- Department of Medicine, Center for Human Nutrition, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Manuel Gutiérrez-Aguilar
- Department of Medicine, Center for Human Nutrition, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Nicole K H Yiew
- Department of Medicine, Center for Human Nutrition, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Andrew J Lutkewitte
- Department of Medicine, Center for Human Nutrition, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Jason M Singer
- Department of Medicine, Center for Human Nutrition, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Kyle S McCommis
- Department of Medicine, Center for Human Nutrition, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Daniel Ferguson
- Department of Medicine, Center for Human Nutrition, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Kim H H Liss
- Department of Pediatrics, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Jun Yoshino
- Department of Medicine, Center for Human Nutrition, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - M Katie Renkemeyer
- Department of Medicine, Center for Human Nutrition, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Gordon I Smith
- Department of Medicine, Center for Human Nutrition, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Kevin Cho
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Justin A Fletcher
- Center for Human Nutrition, University of Texas Southwestern, Dallas, TX 75390, USA
| | - Samuel Klein
- Department of Medicine, Center for Human Nutrition, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Gary J Patti
- Department of Medicine, Center for Human Nutrition, Washington University in St. Louis, St. Louis, MO 63110, USA; Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63110, USA; Siteman Cancer Center, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Shawn C Burgess
- Center for Human Nutrition, University of Texas Southwestern, Dallas, TX 75390, USA
| | - Brian N Finck
- Department of Medicine, Center for Human Nutrition, Washington University in St. Louis, St. Louis, MO 63110, USA.
| |
Collapse
|
10
|
Cicatiello AG, Sagliocchi S, Nappi A, Di Cicco E, Miro C, Murolo M, Stornaiuolo M, Dentice M. Thyroid hormone regulates glutamine metabolism and anaplerotic fluxes by inducing mitochondrial glutamate aminotransferase GPT2. Cell Rep 2022; 38:110409. [PMID: 35196498 PMCID: PMC8889437 DOI: 10.1016/j.celrep.2022.110409] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 12/29/2021] [Accepted: 01/27/2022] [Indexed: 12/27/2022] Open
Abstract
Thyroid hormones (THs) are key metabolic regulators coordinating short- and long-term energy needs. In skeletal muscle, THs modulate energy metabolism in pathophysiological conditions. Indeed, hypo- and hyperthyroidism are leading causes of muscle weakness and strength; however, the metabolic pathways underlying these effects are still poorly understood. Using molecular, biochemical, and isotope-tracing approaches combined with mass spectrometry and denervation experiments, we find that THs regulate glutamine metabolism and anaplerotic fluxes by up-regulating the glutamate pyruvate transaminase 2 (GPT2) gene. In humans, GPT2 autosomal recessive mutations cause a neurological syndrome characterized by intellectual disability, microcephaly, and progressive motor symptoms. Here, we demonstrate a role of the TH/GPT2 axis in skeletal muscle in which it regulates muscle weight and fiber diameter in resting and atrophic conditions and results in protection from muscle loss during atrophy. These results describe an anabolic route by which THs rewire glutamine metabolism toward the maintenance of muscle mass. THs induce the expression of the mitochondrial GPT2 gene in skeletal muscle The GPT2 up-regulation by THs enhances anaplerotic cycles and α-KG production GPT2 is reduced during muscle atrophy and is reactivated by THs treatment GPT2 KO+/– mice undergo muscle loss that is partially attenuated by THs
Collapse
Affiliation(s)
| | - Serena Sagliocchi
- Department of Clinical Medicine and Surgery, University of Naples "Federico II", Naples, NA 80138 Italy
| | - Annarita Nappi
- Department of Clinical Medicine and Surgery, University of Naples "Federico II", Naples, NA 80138 Italy
| | - Emery Di Cicco
- Department of Clinical Medicine and Surgery, University of Naples "Federico II", Naples, NA 80138 Italy
| | - Caterina Miro
- Department of Clinical Medicine and Surgery, University of Naples "Federico II", Naples, NA 80138 Italy
| | - Melania Murolo
- Department of Clinical Medicine and Surgery, University of Naples "Federico II", Naples, NA 80138 Italy
| | - Mariano Stornaiuolo
- Department of Pharmacy, University of Naples "Federico II", Naples, NA 80138 Italy
| | - Monica Dentice
- Department of Clinical Medicine and Surgery, University of Naples "Federico II", Naples, NA 80138 Italy; CEINGE-Biotecnologie Avanzate Scarl, Naples, NA 80131, Italy.
| |
Collapse
|
11
|
Mitra D, Vega-Rubin-de-Celis S, Royla N, Bernhardt S, Wilhelm H, Tarade N, Poschet G, Buettner M, Binenbaum I, Borgoni S, Vetter M, Kantelhardt EJ, Thomssen C, Chatziioannou A, Hell R, Kempa S, Müller-Decker K, Wiemann S. Abrogating GPT2 in triple-negative breast cancer inhibits tumor growth and promotes autophagy. Int J Cancer 2021; 148:1993-2009. [PMID: 33368291 DOI: 10.1002/ijc.33456] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [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: 06/03/2020] [Revised: 11/09/2020] [Accepted: 11/30/2020] [Indexed: 12/16/2022]
Abstract
Uncontrolled proliferation and altered metabolic reprogramming are hallmarks of cancer. Active glycolysis and glutaminolysis are characteristic features of these hallmarks and required for tumorigenesis. A fine balance between cancer metabolism and autophagy is a prerequisite of homeostasis within cancer cells. Here we show that glutamate pyruvate transaminase 2 (GPT2), which serves as a pivot between glycolysis and glutaminolysis, is highly upregulated in aggressive breast cancers, particularly the triple-negative breast cancer subtype. Abrogation of this enzyme results in decreased tricarboxylic acid cycle intermediates, which promotes the rewiring of glucose carbon atoms and alterations in nutrient levels. Concordantly, loss of GPT2 results in an impairment of mechanistic target of rapamycin complex 1 activity as well as the induction of autophagy. Furthermore, in vivo xenograft studies have shown that autophagy induction correlates with decreased tumor growth and that markers of induced autophagy correlate with low GPT2 levels in patient samples. Taken together, these findings indicate that cancer cells have a close network between metabolic and nutrient sensing pathways necessary to sustain tumorigenesis and that aminotransferase reactions play an important role in maintaining this balance.
Collapse
Affiliation(s)
- Devina Mitra
- Division of Molecular Genome Analysis, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Faculty of Biosciences, University of Heidelberg, Heidelberg, Germany
| | - Silvia Vega-Rubin-de-Celis
- Division of Molecular Genome Analysis, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Institute of Cell Biology (Cancer Research), University Hospital Essen, Essen, Germany
| | - Nadine Royla
- Max-Delbrueck-Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin Institute for Medical Systems Biology (BIMSB), Berlin, Germany
| | - Stephan Bernhardt
- Division of Molecular Genome Analysis, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Faculty of Biosciences, University of Heidelberg, Heidelberg, Germany
| | - Heike Wilhelm
- Division of Molecular Genome Analysis, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Nooraldeen Tarade
- Division of Molecular Genome Analysis, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Faculty of Biosciences, University of Heidelberg, Heidelberg, Germany
| | - Gernot Poschet
- Centre for Organismal Studies (COS), University of Heidelberg, Heidelberg, Germany
| | - Michael Buettner
- Centre for Organismal Studies (COS), University of Heidelberg, Heidelberg, Germany
| | - Ilona Binenbaum
- Department of Biology, University of Patras, Patras, Greece
- Institute of Biology, Medicinal Chemistry and Biotechnology, National Hellenic Research Foundation, Athens, Greece
- Division of Medical Informatics for Translational Oncology, German Cancer Research Centre, Heidelberg, Germany
- Division of Pediatric Hematology-Oncology, First Department of Pediatrics, National and Kapodistrian University of Athens, Greece
| | - Simone Borgoni
- Division of Molecular Genome Analysis, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Faculty of Biosciences, University of Heidelberg, Heidelberg, Germany
| | - Martina Vetter
- Department of Gynaecology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany
| | - Eva Johanna Kantelhardt
- Department of Gynaecology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany
| | - Christoph Thomssen
- Department of Gynaecology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany
| | - Aristotelis Chatziioannou
- Institute of Biology, Medicinal Chemistry and Biotechnology, National Hellenic Research Foundation, Athens, Greece
- e-NIOS PC, Athens, Greece
| | - Rüdiger Hell
- Centre for Organismal Studies (COS), University of Heidelberg, Heidelberg, Germany
| | - Stefan Kempa
- Max-Delbrueck-Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin Institute for Medical Systems Biology (BIMSB), Berlin, Germany
- Max-Delbrueck-Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin Institute of Health (BIH), Berlin, Germany
| | - Karin Müller-Decker
- DKFZ Tumor Models Core Facility, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Stefan Wiemann
- Division of Molecular Genome Analysis, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Faculty of Biosciences, University of Heidelberg, Heidelberg, Germany
| |
Collapse
|
12
|
Binaafar S, Razmara E, Mahdieh N, Sahebjame H, Tavasoli AR, Garshasbi M. A novel missense variant in GPT2 causes non-syndromic autosomal recessive intellectual disability in a consanguineous Iranian family. Eur J Med Genet 2020; 63:103853. [PMID: 31978613 DOI: 10.1016/j.ejmg.2020.103853] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [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: 10/26/2019] [Revised: 12/15/2019] [Accepted: 01/17/2020] [Indexed: 12/28/2022]
Abstract
Intellectual disability (ID) affects 1-3% of the general population worldwide. Genetic factors play an undeniable role in the etiology of Non-Syndromic Intellectual disability (NS-ID). Nowadays, whole-exome sequencing (WES) technique is used frequently to identify the causative genes in such heterogeneous diseases. Herein, we subjected four patients with initial diagnostics of NS-ID in a consanguineous Iranian family. To find the possible genetic cause(s), Trio-WES was performed on the proband and his both healthy parents. Sanger sequencing was performed to confirm the identified variant by WES and also investigate whether it co-segregates with the patients' phenotype in the family. Using several online in-silico predictors, the probable impacts of the variant on structure and function of GPT2 protein were predicted. A novel variant, c.266A>G; p.(Glu89Gly), in exon 3 of GPT2 (NM_133443.3) was identified using Trio-WES. The candidate variant was also verified by Sanger sequencing. All affected members showed the common clinical features suffering from a non-progressive mild-to-severe ID. Also, different clinical observations compared to previously reported cases such as no facial features, no obvious structural malformations, ability to speak but with difficulty, and lack of any morphological defects were noted for the first time in this family. The c.266A>G; p.(Glu89Gly) variant reported here is the sixth variant identified up to now in the GPT2 gene, to be associated with NS-ID. Our data support the potential malfunction of the substituted GPT2 protein resulted from the novel variant, however, we strongly suggest confirming this finding more by doing functional analysis.
Collapse
Affiliation(s)
- Sima Binaafar
- Cardiogenetic Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Ehsan Razmara
- Australian Regenerative Medicine Institute, Monash University, Clayton, VIC, 3800, Australia
| | - Nejat Mahdieh
- Cardiogenetic Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Hamidreza Sahebjame
- Department of Biology, Faculty of Basic Science, Gonbad Kavous University, Gonbad Kavous, Golestan, Iran
| | - Ali Reza Tavasoli
- Myelin Disorders Clinic, Pediatric Neurology Division, Children's Medical Center, Pediatrics Center of Excellence, Tehran University of Medical Sciences, Tehran, Iran
| | - Masoud Garshasbi
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran.
| |
Collapse
|
13
|
Weise SE, Liu T, Childs KL, Preiser AL, Katulski HM, Perrin-Porzondek C, Sharkey TD. Transcriptional Regulation of the Glucose-6-Phosphate/Phosphate Translocator 2 Is Related to Carbon Exchange Across the Chloroplast Envelope. Front Plant Sci 2019; 10:827. [PMID: 31316533 PMCID: PMC6609314 DOI: 10.3389/fpls.2019.00827] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Accepted: 06/07/2019] [Indexed: 05/02/2023]
Abstract
The exchange of reduced carbon across the inner chloroplast envelope has a large impact on photosynthesis and growth. Under steady-state conditions it is thought that glucose 6-phosphate (G6P) does not cross the chloroplast membrane. However, growth at high CO2, or disruption of starch metabolism can result in the GPT2 gene for a G6P/Pi translocator to be expressed presumably allowing G6P exchange across the chloroplast envelope. We found that after an increase in light, the transcript for GPT2 transiently increases several 100-fold within 2 h in both the Col-0 and WS ecotypes of Arabidopsis thaliana. The increase in transcript for GPT2 is preceded by an increase in transcript for many transcription factors including Redox Responsive Transcription Factor 1 (RRTF1). The increase in GPT2 transcript after exposure to high light is suppressed in a mutant lacking the RRTF1 transcription factor. The GPT2 response was also suppressed in a mutant with a T-DNA insert in the gene for the triose-phosphate/Pi translocator (TPT). However, plants lacking TPT still had a robust rise in RRTF1 transcript in response to high light. From this, we conclude that both RRTF1 (and possibly other transcription factors) and high amounts of cytosolic triose phosphate are required for induction of the expression of GPT2. We hypothesize that transient GPT2 expression and subsequent translation is adaptive, allowing G6P to move into the chloroplast from the cytosol. The imported G6P can be used for starch synthesis or may flow directly into the Calvin-Benson cycle via an alternative pathway (the G6P shunt), which could be important for regulating and stabilizing photosynthetic electron transport and carbon metabolism.
Collapse
Affiliation(s)
- Sean E. Weise
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, United States
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, United States
| | - Tiffany Liu
- Department of Plant Biology, Michigan State University, East Lansing, MI, United States
| | - Kevin L. Childs
- Department of Plant Biology, Michigan State University, East Lansing, MI, United States
| | - Alyssa L. Preiser
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, United States
| | - Hailey M. Katulski
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, United States
| | | | - Thomas D. Sharkey
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, United States
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, United States
- Plant Resilience Institute, Michigan State University, East Lansing, MI, United States
- *Correspondence: Thomas D. Sharkey,
| |
Collapse
|
14
|
Smith B, Schafer XL, Ambeskovic A, Spencer CM, Land H, Munger J. Addiction to Coupling of the Warburg Effect with Glutamine Catabolism in Cancer Cells. Cell Rep. 2016;17:821-836. [PMID: 27732857 PMCID: PMC5108179 DOI: 10.1016/j.celrep.2016.09.045] [Citation(s) in RCA: 105] [Impact Index Per Article: 15.0] [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: 07/22/2016] [Revised: 08/25/2016] [Accepted: 09/14/2016] [Indexed: 12/23/2022] Open
Abstract
Metabolic reprogramming is critical to oncogenesis, but the emergence and function of this profound reorganization remain poorly understood. Here we find that cooperating oncogenic mutations drive large-scale metabolic reprogramming, which is both intrinsic to cancer cells and obligatory for the transition to malignancy. This involves synergistic regulation of several genes encoding metabolic enzymes, including the lactate dehydrogenases LDHA and LDHB and mitochondrial glutamic pyruvate transaminase 2 (GPT2). Notably, GPT2 engages activated glycolysis to drive the utilization of glutamine as a carbon source for TCA cycle anaplerosis in colon cancer cells. Our data indicate that the Warburg effect supports oncogenesis via GPT2-mediated coupling of pyruvate production to glutamine catabolism. Although critical to the cancer phenotype, GPT2 activity is dispensable in cells that are not fully transformed, thus pinpointing a metabolic vulnerability specifically associated with cancer cell progression to malignancy.
Collapse
|
15
|
Wong JH, Hashimoto T. Novel Arabidopsis microtubule-associated proteins track growing microtubule plus ends. BMC Plant Biol 2017; 17:33. [PMID: 28148225 PMCID: PMC5288973 DOI: 10.1186/s12870-017-0987-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 01/25/2017] [Indexed: 05/07/2023]
Abstract
BACKGROUND Microtubules (MTs) are polarized polymers with highly dynamic plus ends that stochastically switch between growth and shrinkage phases. In eukaryotic cells, a plethora of MT-associated proteins (MAPs) regulate the dynamics and higher-order organization of MTs to mediate distinct cellular functions. Plus-end tracking proteins (+TIPs) are a group of MAPs that specifically accumulate at the growing MT plus ends, where they modulate the behavior of the MT plus ends and mediate interactions with cellular targets. Although several functionally important + TIP proteins have been characterized in yeast and animals, little is known about this group of proteins in plants. RESULTS We report here that two homologous MAPs from Arabidopsis thaliana, Growing Plus-end Tracking 1 (GPT1) and GPT2 (henceforth GPT1/2), contain basic MT-binding regions at their central and C-terminal regions, and bind directly to MTs in vitro. Interestingly, GPT1/2 preferentially accumulated at the growing plus ends of cortical MTs in interphase Arabidopsis cells. When the GPT1/12-decorated growing plus ends switched to rapid depolymerization, GPT1/2 dissociated from the MT plus ends. Conversely, when the depolymerizing ends were rescued and started to polymerize again, GPT1/2 were immediately recruited to the growing MT tips. This tip tracking behavior of GPT proteins does not depend on the two established plant + TIPs, End-Binding protein 1 (EB1) and SPIRAL1 (SPR1). CONCLUSIONS The Arabidopsis MAPs GPT1 and GPT2 bind MTs directly through their basic regions. These MAPs track the plus ends of growing MTs independently of EB1 and SPR1 and represent a novel plant-specific + TIP family.
Collapse
Affiliation(s)
- Jeh Haur Wong
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Takayama 8916-5, Ikoma, Nara, 630-0192, Japan
| | - Takashi Hashimoto
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Takayama 8916-5, Ikoma, Nara, 630-0192, Japan.
| |
Collapse
|
16
|
Lobo-Prada T, Sticht H, Bogantes-Ledezma S, Ekici A, Uebe S, Reis A, Leal A. A Homozygous Mutation in GPT2 Associated with Nonsyndromic Intellectual Disability in a Consanguineous Family from Costa Rica. JIMD Rep 2017; 36:59-66. [PMID: 28130718 DOI: 10.1007/8904_2016_40] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 06/01/2023] Open
Abstract
Intellectual disability is a highly heterogeneous disease that affects the central nervous system and impairs patients' ability to function independently. Despite multiples genes involved in the etiology of disease, most of the genetic background is yet to be discovered. We used runs of homozygosity and exome sequencing to study a large Costa Rican family with four individuals affected with severe intellectual disability and found a novel homozygous missense mutation, p. 96G>R, c. 286G>A, in all affected individuals. This gene encodes for a pyridoxal enzyme involved in the production of the neurotransmitter glutamate and is highly expressed in the white matter of brain and cerebellum. Protein modeling of GPT2 predicted that the mutation is located in a loop where the substrate binds to the active site of the enzyme, therefore, suggesting that the catalytic activity is impaired. With our report of a second mutation we fortify the importance of GPT2 as a novel cause of autosomal recessive nonsyndromic intellectual disability and support the premise that GPT2 is highly important for the neurodevelopment of the central nervous system. SYNOPSIS The mutation p. 96G>R c. 286G>A in GPT2, located in a loop where the substrate binds to the active site of the enzyme, fortifies the importance of GPT2 in the pathogenesis of nonsyndromic intellectual disability.
Collapse
|
17
|
Ouyang Q, Nakayama T, Baytas O, Davidson SM, Yang C, Schmidt M, Lizarraga SB, Mishra S, Ei-Quessny M, Niaz S, Gul Butt M, Imran Murtaza S, Javed A, Chaudhry HR, Vaughan DJ, Hill RS, Partlow JN, Yoo SY, Lam AT, Nasir R, Al-Saffar M, Barkovich AJ, Schwede M, Nagpal S, Rajab A, DeBerardinis RJ, Housman DE, Mochida GH, Morrow EM. Mutations in mitochondrial enzyme GPT2 cause metabolic dysfunction and neurological disease with developmental and progressive features. Proc Natl Acad Sci U S A 2016; 113:E5598-607. [PMID: 27601654 DOI: 10.1073/pnas.1609221113] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Mutations that cause neurological phenotypes are highly informative with regard to mechanisms governing human brain function and disease. We report autosomal recessive mutations in the enzyme glutamate pyruvate transaminase 2 (GPT2) in large kindreds initially ascertained for intellectual and developmental disability (IDD). GPT2 [also known as alanine transaminase 2 (ALT2)] is one of two related transaminases that catalyze the reversible addition of an amino group from glutamate to pyruvate, yielding alanine and α-ketoglutarate. In addition to IDD, all affected individuals show postnatal microcephaly and ∼80% of those followed over time show progressive motor symptoms, a spastic paraplegia. Homozygous nonsense p.Arg404* and missense p.Pro272Leu mutations are shown biochemically to be loss of function. The GPT2 gene demonstrates increasing expression in brain in the early postnatal period, and GPT2 protein localizes to mitochondria. Akin to the human phenotype, Gpt2-null mice exhibit reduced brain growth. Through metabolomics and direct isotope tracing experiments, we find a number of metabolic abnormalities associated with loss of Gpt2. These include defects in amino acid metabolism such as low alanine levels and elevated essential amino acids. Also, we find defects in anaplerosis, the metabolic process involved in replenishing TCA cycle intermediates. Finally, mutant brains demonstrate misregulated metabolites in pathways implicated in neuroprotective mechanisms previously associated with neurodegenerative disorders. Overall, our data reveal an important role for the GPT2 enzyme in mitochondrial metabolism with relevance to developmental as well as potentially to neurodegenerative mechanisms.
Collapse
|
18
|
Dyson BC, Webster RE, Johnson GN. GPT2: a glucose 6-phosphate/phosphate translocator with a novel role in the regulation of sugar signalling during seedling development. Ann Bot 2014; 113:643-52. [PMID: 24489010 PMCID: PMC3936590 DOI: 10.1093/aob/mct298] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
BACKGROUND AND AIMS GPT2, a glucose 6-phosphate/phosphate translocator, plays an important role in environmental sensing in mature leaves of Arabidopsis thaliana. Its expression has also been detected in arabidopsis seeds and seedlings. In order to examine the role of this protein early in development, germination and seedling growth were studied. METHODS Germination, greening and establishment of seedlings were monitored in both wild-type Arabidopsis thaliana and in a gpt2 T-DNA insertion knockout line. Seeds were sown on agar plates in the presence or absence of glucose and abscisic acid. Relative expression of GPT2 in seedlings was measured using quantitative PCR. KEY RESULTS Plants lacking GPT2 expression were delayed (25-40 %) in seedling establishment, specifically in the process of cotyledon greening (rather than germination). This phenotype could not be rescued by glucose in the growth medium, with greening being hypersensitive to glucose. Germination itself was, however, hyposensitive to glucose in the gpt2 mutant. CONCLUSIONS The expression of GPT2 modulates seedling development and plays a crucial role in determining the response of seedlings to exogenous sugars during their establishment. This allows us to conclude that endogenous sugar signals function in controlling germination and the transition from heterotrophic to autotrophic growth, and that the partitioning of glucose 6-phosphate, or related metabolites, between the cytosol and the plastid modulates these developmental responses.
Collapse
Affiliation(s)
- Beth C. Dyson
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK
| | - Rachel E. Webster
- The Manchester Museum, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Giles N. Johnson
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK
- For correspondence. E-mail
| |
Collapse
|