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Qu JH, Chakir K, Tarasov KV, Riordon DR, Perino MG, Silvester AJ, Lakatta EG. Reprogramming of cardiac phosphoproteome, proteome, and transcriptome confers resilience to chronic adenylyl cyclase-driven stress. eLife 2024; 12:RP88732. [PMID: 38251682 PMCID: PMC10945681 DOI: 10.7554/elife.88732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2024] Open
Abstract
Our prior study (Tarasov et al., 2022) discovered that numerous adaptive mechanisms emerge in response to cardiac-specific overexpression of adenylyl cyclase type 8 (TGAC8) which included overexpression of a large number of proteins. Here, we conducted an unbiased phosphoproteomics analysis in order to determine the role of altered protein phosphorylation in the adaptive heart performance and protection profile of adult TGAC8 left ventricle (LV) at 3-4 months of age, and integrated the phosphoproteome with transcriptome and proteome. Based on differentially regulated phosphoproteins by genotype, numerous stress-response pathways within reprogrammed TGAC8 LV, including PKA, PI3K, and AMPK signaling pathways, predicted upstream regulators (e.g. PDPK1, PAK1, and PTK2B), and downstream functions (e.g. cell viability, protein quality control), and metabolism were enriched. In addition to PKA, numerous other kinases and phosphatases were hyper-phosphorylated in TGAC8 vs. WT. Hyper-phosphorylated transcriptional factors in TGAC8 were associated with increased mRNA transcription, immune responses, and metabolic pathways. Combination of the phosphoproteome with its proteome and with the previously published TGAC8 transcriptome enabled the elucidation of cardiac performance and adaptive protection profiles coordinately regulated at post-translational modification (PTM) (phosphorylation), translational, and transcriptional levels. Many stress-response signaling pathways, i.e., PI3K/AKT, ERK/MAPK, and ubiquitin labeling, were consistently enriched and activated in the TGAC8 LV at transcriptional, translational, and PTM levels. Thus, reprogramming of the cardiac phosphoproteome, proteome, and transcriptome confers resilience to chronic adenylyl cyclase-driven stress. We identified numerous pathways/function predictions via gene sets, phosphopeptides, and phosphoproteins, which may point to potential novel therapeutic targets to enhance heart adaptivity, maintaining heart performance while avoiding cardiac dysfunction.
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Affiliation(s)
- Jia-Hua Qu
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
- Department of Immunology, St. Jude Children’s Research HospitalMemphisUnited States
| | - Khalid Chakir
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Kirill V Tarasov
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Daniel R Riordon
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Maria Grazia Perino
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Allwin Jennifa Silvester
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
| | - Edward G Lakatta
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of HealthBaltimoreUnited States
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Yang Q, Fu J, Wang M, Fang Y, Fu J. MiR-1299 is regulated by KCNQ1OT1 and inhibits cervical cancer progression. Cell Mol Biol (Noisy-le-grand) 2023; 69:166-173. [PMID: 37953567 DOI: 10.14715/cmb/2023.69.10.24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Indexed: 11/14/2023]
Abstract
Cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC) is the most common malignancy of the female genital tract. MiR-1299 serves as a tumor suppressor, while KCNQ1OT1 acts as an oncogene in multiple malignancies. This research was designed to investigate the impacts of miR-1299 and KCNQ1OT1 on CESC progression. The downstream target of miR-1299 and the underlying regulatory mechanism of KCNQ1OT1 action on miR-1299 were explored. RT-qPCR was applied for RNA expression detection in CESC tissues and cells. RNA immunoprecipitation, RNA pulldown and luciferase reporter assays were applied to evaluate the binding between molecules in CESC cells. Cell Counting Kit-8 and colony formation assays were used for the measurement of CESC cell viability and proliferation. Western blotting was utilized to measure levels of apoptosis-related in CESC cells. MiR-1299 was downregulated in CESC tissues and presented a negative correlation with KCNQ1OT1 expression. KCNQ1OT1 was directly bound to miR-1299 to negatively modulate miR-1299 expression in CESC cells. The proliferative ability of CESC cells was suppressed by miR-1299 overexpression and was facilitated by KCNQ1OT1 overexpression. CESC cells apoptosis was promoted by miR-1299 mimics and inhibited by KCNQ1OT1 overexpression. In addition, in in vivo studies, miR-1299 overexpression rescued the effects of KCNQ1OT1 overexpression on CESC xenograft tumor growth. Finally, KCNQ1OT1 was bound to miR-1299 to upregulate PDPK1 expression in CESC cells. Collectively, miR-1299 was regulated by KCNQ1OT1 and inhibited CESC progression in vivo and in vitro, suggesting the tumor-suppressor role of miR-1299 for CESC.
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Affiliation(s)
- Qian Yang
- Department of Gynecology, The Fourth Affiliated Hospital of Nanjing Medical University, Nanjing 211500, Jiangsu, China.
| | - Jing Fu
- Department of Emergency, Huai'an Second People's Hospital, The Affiliated Huai'an Hospital of Xuzhou Medical University, Huai'an 223002, Jiangsu, China.
| | - Min Wang
- Department of Gynecology, The Affiliated Suqian Hospital of Xuzhou Medical University, Suqian 223800, Jiangsu, China.
| | - Yuelan Fang
- Department of Gynecology, The Affiliated Suqian Hospital of Xuzhou Medical University, Suqian 223800, Jiangsu, China.
| | - Jian Fu
- Department of Gynecology, The Affiliated Suqian Hospital of Xuzhou Medical University, Suqian 223800, Jiangsu, China.
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Li C, Zhou Y, Niu Y, He W, Wang X, Zhang X, Wu Y, Zhang W, Zhao L, Zheng H, Song W, Gao H. Deficiency of Pdk1 drives heart failure by impairing taurine homeostasis through Slc6a6. FASEB J 2023; 37:e23134. [PMID: 37561545 DOI: 10.1096/fj.202300272r] [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: 02/14/2023] [Revised: 06/19/2023] [Accepted: 07/27/2023] [Indexed: 08/11/2023]
Abstract
3-Phosphoinositide-dependent protein kinase-1 (Pdk1) as a serine/threonine protein kinase plays a critical role in multiple signaling pathways. Analysis of the gene expression omnibus database showed that Pdk1 was significantly downregulated in patients with heart diseases. Gene set enrichment analysis of the proteomics dataset identified apoptotic- and metabolism-related signaling pathways directly targeted by Pdk1. Previously, our research indicated that Pdk1 deletion-induced metabolic changes might be involved in the pathogenesis of heart failure; however, the underlying mechanism remains elusive. Here, we demonstrated that deficiency of Pdk1 resulted in apoptosis, oxidative damage, and disturbed metabolism, both in vivo and in vitro. Furthermore, profiling of metabonomics by 1 H-NMR demonstrated that taurine was the major differential metabolite in the heart of Pdk1-knockout mice. Taurine treatment significantly reduced the reactive oxygen species production and apoptosis, improved cardiac function, and prolonged the survival time in Pdk1 deficient mice. Proteomic screening identified solute carrier family 6 member 6 (Slc6a6) as the downstream that altered taurine levels in Pdk1-expression cells. Consistently, cellular apoptosis and oxidative damage were rescued by Slc6a6 in abnormal Pdk1 expression cells. These findings collectively suggest that Pdk1 deficiency induces heart failure via disturbances in taurine homeostasis, triggered by Slc6a6.
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Affiliation(s)
- Chen Li
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, China
- Key Laboratory of Alzheimer's Disease of Zhejiang Province, Institute of Aging, Wenzhou Medical University, Wenzhou, China
- Key Laboratory of Efficacy Evaluation of Traditional Chinese Medicine and Encephalopathy Research of Zhejiang Province, Wenzhou, China
| | - Yi Zhou
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, China
| | - Yan Niu
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, China
| | - Wenting He
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, China
| | - Xinyi Wang
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, China
| | - Xi Zhang
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, China
| | - Yali Wu
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, China
| | - Wenli Zhang
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, China
| | - Liangcai Zhao
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, China
| | - Hong Zheng
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, China
| | - Weihong Song
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, China
- Key Laboratory of Alzheimer's Disease of Zhejiang Province, Institute of Aging, Wenzhou Medical University, Wenzhou, China
| | - Hongchang Gao
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, China
- Key Laboratory of Alzheimer's Disease of Zhejiang Province, Institute of Aging, Wenzhou Medical University, Wenzhou, China
- Key Laboratory of Efficacy Evaluation of Traditional Chinese Medicine and Encephalopathy Research of Zhejiang Province, Wenzhou, China
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Fan S, Spence JP, Feng Y, Hansen MEB, Terhorst J, Beltrame MH, Ranciaro A, Hirbo J, Beggs W, Thomas N, Nyambo T, Mpoloka SW, Mokone GG, Njamnshi A, Folkunang C, Meskel DW, Belay G, Song YS, Tishkoff SA. Whole-genome sequencing reveals a complex African population demographic history and signatures of local adaptation. Cell 2023; 186:923-939.e14. [PMID: 36868214 PMCID: PMC10568978 DOI: 10.1016/j.cell.2023.01.042] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Revised: 10/16/2022] [Accepted: 01/30/2023] [Indexed: 03/05/2023]
Abstract
We conduct high coverage (>30×) whole-genome sequencing of 180 individuals from 12 indigenous African populations. We identify millions of unreported variants, many predicted to be functionally important. We observe that the ancestors of southern African San and central African rainforest hunter-gatherers (RHG) diverged from other populations >200 kya and maintained a large effective population size. We observe evidence for ancient population structure in Africa and for multiple introgression events from "ghost" populations with highly diverged genetic lineages. Although currently geographically isolated, we observe evidence for gene flow between eastern and southern Khoesan-speaking hunter-gatherer populations lasting until ∼12 kya. We identify signatures of local adaptation for traits related to skin color, immune response, height, and metabolic processes. We identify a positively selected variant in the lightly pigmented San that influences pigmentation in vitro by regulating the enhancer activity and gene expression of PDPK1.
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Affiliation(s)
- Shaohua Fan
- State Key Laboratory of Genetic Engineering, Human Phenome Institute, Zhangjiang Fudan International Innovation Center, School of Life Science, Fudan University, Shanghai, 200438, China; Department of Genetics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jeffrey P Spence
- Department of Genetics, School of Medicine, Stanford University, Stanford, CA 94305, USA
| | - Yuanqing Feng
- Department of Genetics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Matthew E B Hansen
- Department of Genetics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jonathan Terhorst
- Department of Statistics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Marcia H Beltrame
- Department of Genetics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Alessia Ranciaro
- Department of Genetics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jibril Hirbo
- Department of Genetics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - William Beggs
- Department of Genetics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Neil Thomas
- Computer Science Division, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Thomas Nyambo
- Department of Biochemistry, Kampala International University in Tanzania, P.O. Box 9790, Dar es Salaam, Tanzania
| | - Sununguko Wata Mpoloka
- Department of Biological Sciences, Faculty of Science, University of Botswana Gaborone, Private Bag UB 0022, Gaborone, Botswana
| | - Gaonyadiwe George Mokone
- Department of Biomedical Sciences, Faculty of Medicine, University of Botswana Gaborone, Private Bag UB 0022, Gaborone, Botswana
| | - Alfred Njamnshi
- Department of Neurology, Central Hospital Yaoundé; Brain Research Africa Initiative (BRAIN), Neuroscience Lab, Faculty of Medicine and Biomedical Sciences, The University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - Charles Folkunang
- Department of Pharmacotoxicology and Pharmacokinetics, Faculty of Medicine and Biomedical Sciences, The University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - Dawit Wolde Meskel
- Department of Microbial Cellular and Molecular Biology, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia
| | - Gurja Belay
- Department of Microbial Cellular and Molecular Biology, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia
| | - Yun S Song
- Computer Science Division, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Statistics, University of California, Berkeley, Berkeley, CA 94720, USA; Chan Zuckerberg Biohub, San Francisco, CA 94158, USA
| | - Sarah A Tishkoff
- Department of Genetics, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA.
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5
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Wang X, Yu J, Liu X, Luo D, Li Y, Song L, Jiang X, Yin X, Wang Y, Chai L, Luo T, Jing J, Shi H. PSMG2-controlled proteasome-autophagy balance mediates the tolerance for MEK-targeted therapy in triple-negative breast cancer. Cell Rep Med 2022; 3:100741. [PMID: 36099919 PMCID: PMC9512673 DOI: 10.1016/j.xcrm.2022.100741] [Citation(s) in RCA: 4] [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: 03/15/2022] [Revised: 06/21/2022] [Accepted: 08/23/2022] [Indexed: 05/29/2023]
Abstract
Although the MAPK pathway is aberrantly activated in triple-negative breast cancers (TNBCs), the clinical outcome of MEK-targeted therapy is still poor. Through a genome-wide CRISPR-Cas9 library screening, we find that inhibition of PSMG2 sensitizes TNBC cells BT549 and MB468 to the MEK inhibitor AZD6244. Mechanistically, PSMG2 knockdown impairs proteasome function, which in turn activates autophagy-mediated PDPK1 degradation. The PDPK1 degradation significantly enhances AZD6244-induced tumor cell growth inhibition by interrupting the negative feedback signals toward the AKT pathway. Consistently, co-targeting proteasomes and MEK with inhibitors synergistically suppresses tumor cell growth. The autophagy inhibitor chloroquine partially relieves the PDPK1 degradation and reverses the growth inhibition induced by combinatorial inhibition of MEK and proteasome. The combination regimen with the proteasome inhibitor MG132 plus AZD6244 synergistically inhibits tumor growth in a 4T1 xenograft mouse model. In summary, our study not only unravels the mechanism of MEK inhibitor resistance but also provides a combinatorial therapeutic strategy for TNBC in clinics.
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Affiliation(s)
- Xueyan Wang
- Laboratory of Integrative Medicine, Clinical Research Center for Breast, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center, Chengdu, Sichuan 610041, China
| | - Jing Yu
- Laboratory of Integrative Medicine, Clinical Research Center for Breast, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center, Chengdu, Sichuan 610041, China
| | - Xiaowei Liu
- Laboratory of Integrative Medicine, Clinical Research Center for Breast, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center, Chengdu, Sichuan 610041, China
| | - Dan Luo
- Department of Immunology, School of Basic Medical Sciences, Chengdu Medical College, Chengdu, Sichuan 610500, China
| | - Yanchu Li
- West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Linlin Song
- Department of Ultrasound and Laboratory of Ultrasound Medicine, West China Hospital, Sichuan University and Collaborative Innovation Center, Chengdu, Sichuan 610041, China
| | - Xian Jiang
- Laboratory of Integrative Medicine, Clinical Research Center for Breast, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center, Chengdu, Sichuan 610041, China
| | - Xiaomeng Yin
- Department of Biotherapy, West China Hospital, and State Key Laboratory of Biotherapy, Sichuan University, Chengdu, Sichuan 610041, China
| | - Yan Wang
- Research Core Facility, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Li Chai
- Research Core Facility, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Ting Luo
- Laboratory of Integrative Medicine, Clinical Research Center for Breast, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center, Chengdu, Sichuan 610041, China
| | - Jing Jing
- Laboratory of Integrative Medicine, Clinical Research Center for Breast, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center, Chengdu, Sichuan 610041, China.
| | - Hubing Shi
- Laboratory of Integrative Medicine, Clinical Research Center for Breast, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center, Chengdu, Sichuan 610041, China.
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6
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Cai W, Nguyen MQ, Wilski NA, Purwin TJ, Vernon M, Tiago M, Aplin AE. A Genome-Wide Screen Identifies PDPK1 as a Target to Enhance the Efficacy of MEK1/2 Inhibitors in NRAS Mutant Melanoma. Cancer Res 2022; 82:2625-2639. [PMID: 35657206 PMCID: PMC9298960 DOI: 10.1158/0008-5472.can-21-3217] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [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: 09/22/2021] [Revised: 04/22/2022] [Accepted: 05/31/2022] [Indexed: 01/21/2023]
Abstract
Melanomas frequently harbor activating NRAS mutations. However, limited advance has been made in developing targeted therapy options for patients with NRAS mutant melanoma. MEK inhibitors (MEKi) show modest efficacy in the clinic and their actions need to be optimized. In this study, we performed a genome-wide CRISPR-Cas9-based screen and demonstrated that loss of phosphoinositide-dependent kinase-1 (PDPK1) enhances the efficacy of MEKi. The synergistic effects of PDPK1 loss and MEKi was validated in NRAS mutant melanoma cell lines using pharmacologic and molecular approaches. Combined PDPK1 inhibitors (PDPK1i) with MEKi suppressed NRAS mutant xenograft growth and induced gasdermin E-associated pyroptosis. In an immune-competent allograft model, PDPK1i+MEKi increased the ratio of intratumoral CD8+ T cells, delayed tumor growth, and prolonged survival; the combination treatment was less effective against tumors in immune-deficient mice. These data suggest PDPK1i+MEKi as an efficient immunostimulatory strategy against NRAS mutant melanoma. SIGNIFICANCE Targeting PDPK1 stimulates antitumor immunity and sensitizes NRAS mutant melanoma to MEK inhibition, providing rationale for the clinical development of a combinatorial approach for treating patients with melanoma.
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Affiliation(s)
- Weijia Cai
- Department of Cancer Biology, Thomas Jefferson University, Philadelphia, PA 19107
| | - Mai Q. Nguyen
- Department of Cancer Biology, Thomas Jefferson University, Philadelphia, PA 19107
| | - Nicole A. Wilski
- Department of Cancer Biology, Thomas Jefferson University, Philadelphia, PA 19107
| | - Timothy J. Purwin
- Department of Cancer Biology, Thomas Jefferson University, Philadelphia, PA 19107
| | - Megane Vernon
- Department of Cancer Biology, Thomas Jefferson University, Philadelphia, PA 19107
| | - Manoela Tiago
- Department of Cancer Biology, Thomas Jefferson University, Philadelphia, PA 19107
| | - Andrew E. Aplin
- Department of Cancer Biology, Thomas Jefferson University, Philadelphia, PA 19107
- Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107
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7
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Isa R, Horinaka M, Tsukamoto T, Mizuhara K, Fujibayashi Y, Taminishi-Katsuragawa Y, Okamoto H, Yasuda S, Kawaji-Kanayama Y, Matsumura-Kimoto Y, Mizutani S, Shimura Y, Taniwaki M, Sakai T, Kuroda J. The Rationale for the Dual-Targeting Therapy for RSK2 and AKT in Multiple Myeloma. Int J Mol Sci 2022; 23:ijms23062919. [PMID: 35328342 PMCID: PMC8949999 DOI: 10.3390/ijms23062919] [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] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 03/03/2022] [Accepted: 03/04/2022] [Indexed: 02/05/2023] Open
Abstract
Multiple myeloma (MM) is characterized by remarkable cytogenetic/molecular heterogeneity among patients and intraclonal diversity even in a single patient. We previously demonstrated that PDPK1, the master kinase of series of AGC kinases, is universally active in MM, and plays pivotal roles in cell proliferation and cell survival of myeloma cells regardless of the profiles of cytogenetic and genetic abnormalities. This study investigated the therapeutic efficacy and mechanism of action of dual blockade of two major PDPK1 substrates, RSK2 and AKT, in MM. The combinatory treatment of BI-D1870, an inhibitor for N-terminal kinase domain (NTKD) of RSK2, and ipatasertib, an inhibitor for AKT, showed the additive to synergistic anti-tumor effect on human MM-derived cell lines (HMCLs) with active RSK2-NTKD and AKT, by enhancing apoptotic induction with BIM and BID activation. Moreover, the dual blockade of RSK2 and AKT exerted robust molecular effects on critical gene sets associated with myeloma pathophysiologies, such as those with MYC, mTOR, STK33, ribosomal biogenesis, or cell-extrinsic stimuli of soluble factors, in HMCLs. These results provide the biological and molecular rationales for the dual-targeting strategy for RSK2 and AKT, which may overcome the therapeutic difficulty due to cytogenetic/molecular heterogeneity in MM.
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Affiliation(s)
- Reiko Isa
- Division of Hematology and Oncology, Department of Medicine, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan; (R.I.); (T.T.); (K.M.); (Y.F.); (Y.T.-K.); (H.O.); (Y.K.-K.); (Y.M.-K.); (S.M.); (Y.S.); (M.T.)
| | - Mano Horinaka
- Department of Drug Discovery Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan; (M.H.); (S.Y.); (T.S.)
| | - Taku Tsukamoto
- Division of Hematology and Oncology, Department of Medicine, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan; (R.I.); (T.T.); (K.M.); (Y.F.); (Y.T.-K.); (H.O.); (Y.K.-K.); (Y.M.-K.); (S.M.); (Y.S.); (M.T.)
| | - Kentaro Mizuhara
- Division of Hematology and Oncology, Department of Medicine, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan; (R.I.); (T.T.); (K.M.); (Y.F.); (Y.T.-K.); (H.O.); (Y.K.-K.); (Y.M.-K.); (S.M.); (Y.S.); (M.T.)
| | - Yuto Fujibayashi
- Division of Hematology and Oncology, Department of Medicine, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan; (R.I.); (T.T.); (K.M.); (Y.F.); (Y.T.-K.); (H.O.); (Y.K.-K.); (Y.M.-K.); (S.M.); (Y.S.); (M.T.)
| | - Yoko Taminishi-Katsuragawa
- Division of Hematology and Oncology, Department of Medicine, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan; (R.I.); (T.T.); (K.M.); (Y.F.); (Y.T.-K.); (H.O.); (Y.K.-K.); (Y.M.-K.); (S.M.); (Y.S.); (M.T.)
| | - Haruya Okamoto
- Division of Hematology and Oncology, Department of Medicine, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan; (R.I.); (T.T.); (K.M.); (Y.F.); (Y.T.-K.); (H.O.); (Y.K.-K.); (Y.M.-K.); (S.M.); (Y.S.); (M.T.)
| | - Shusuke Yasuda
- Department of Drug Discovery Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan; (M.H.); (S.Y.); (T.S.)
| | - Yuka Kawaji-Kanayama
- Division of Hematology and Oncology, Department of Medicine, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan; (R.I.); (T.T.); (K.M.); (Y.F.); (Y.T.-K.); (H.O.); (Y.K.-K.); (Y.M.-K.); (S.M.); (Y.S.); (M.T.)
| | - Yayoi Matsumura-Kimoto
- Division of Hematology and Oncology, Department of Medicine, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan; (R.I.); (T.T.); (K.M.); (Y.F.); (Y.T.-K.); (H.O.); (Y.K.-K.); (Y.M.-K.); (S.M.); (Y.S.); (M.T.)
| | - Shinsuke Mizutani
- Division of Hematology and Oncology, Department of Medicine, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan; (R.I.); (T.T.); (K.M.); (Y.F.); (Y.T.-K.); (H.O.); (Y.K.-K.); (Y.M.-K.); (S.M.); (Y.S.); (M.T.)
| | - Yuji Shimura
- Division of Hematology and Oncology, Department of Medicine, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan; (R.I.); (T.T.); (K.M.); (Y.F.); (Y.T.-K.); (H.O.); (Y.K.-K.); (Y.M.-K.); (S.M.); (Y.S.); (M.T.)
| | - Masafumi Taniwaki
- Division of Hematology and Oncology, Department of Medicine, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan; (R.I.); (T.T.); (K.M.); (Y.F.); (Y.T.-K.); (H.O.); (Y.K.-K.); (Y.M.-K.); (S.M.); (Y.S.); (M.T.)
- Center for Molecular Diagnostics and Therapeutics, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
| | - Toshiyuki Sakai
- Department of Drug Discovery Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan; (M.H.); (S.Y.); (T.S.)
| | - Junya Kuroda
- Division of Hematology and Oncology, Department of Medicine, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan; (R.I.); (T.T.); (K.M.); (Y.F.); (Y.T.-K.); (H.O.); (Y.K.-K.); (Y.M.-K.); (S.M.); (Y.S.); (M.T.)
- Correspondence:
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8
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Abstract
SummaryThe p21-activated serine/threonine kinases (PAK) play an important role in a variety of cellular functions. However, their role in the smooth muscle response to thrombin, which is activated upon vascular injury and promotes vascular remodelling processes, is not resolved. Here we investigated the role of PAK in thrombin signalling and regulation of tissue factor (TF), the activator of the extrinsic coagulation cascade, in pulmonary artery smooth muscle cells (PASMC), the main cell type responsible for vascular remodelling in pulmonary hypertension. PAK was rapidly phosphorylated in response to thrombin. Thrombin and active PAKT423E phosphorylated p38 MAP kinase (p38MAPK), ERK1/2, phosphatidylinositol-dependent kinase-1 (PDK1) and protein kinase B/Akt (PKB) whereas kinase-deficient PAK1 prevented activation of these kinases by thrombin. In addition, kinase-deficient MKK3 inhibited activation of PDK1 and PKB by thrombin. Further, thrombin and active PAK1 induced TF expression and promoter activity while kinase-deficient PAK1 diminished thrombin-induced TF upregulation. Moreover, kinase-deficient MKK3, PDK1 and PKB inhibited thrombin- and PAK-dependent TF expression and promoter activity. Together these findings show that PAK is a critical element of thrombin signalling in PASMC which is involved in the regulation of TF expression by sequentially activating MKK3/p38MAPK, PDK1 and PKB. Thus, PAK may play an important role in promoting vascular remodelling processes in pulmonary hypertension.
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Affiliation(s)
- Agnes Görlach
- Experimental Pediatric Cardiology, Department of Pediatric Cardiology and Congenital Heart Disease, German Heart Center Munich at the Technical University Munich, Lazarettstrasse 36 , 80636 Munich, Germany.
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9
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PDPK1/RSK2 signaling pathway as the possible therapeutic target for multiple myeloma. Nihon Rinsho 2016; 74 Suppl 5:180-4. [PMID: 30615342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
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10
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Ma Y, McCarty SK, Kapuriya NP, Brendel VJ, Wang C, Zhang X, Jarjoura D, Saji M, Chen CS, Ringel MD. Development of p21 activated kinase-targeted multikinase inhibitors that inhibit thyroid cancer cell migration. J Clin Endocrinol Metab 2013; 98:E1314-22. [PMID: 23709653 PMCID: PMC3733855 DOI: 10.1210/jc.2012-3937] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT The p21 activated kinases (PAKs) are a family of serine/threonine kinases that are downstream effectors of small GTPase Cdc42 and Rac. PAKs regulate cell motility, proliferation, and cytoskeletal rearrangement. PAK isoform expression and activity have been shown to be enhanced in cancer and to function as an oncogene in vivo. PAKs also have been implicated in cancer progression. OBJECTIVE In thyroid cancer, we have previously determined that PAK overactivation is common in the invasive fronts of aggressive tumors and that it is functionally involved in thyroid cancer cell motility using molecular inhibitors. We report the development of two new PAK-inhibiting compounds that were modified from the structure OSU-03012, a previously identified multikinase inhibitor that competitively blocks ATP binding of both phosphoinositide-dependent kinase 1 (PDK1) and PAK1. RESULTS Seventeen compounds were created by combinatorial chemistry predicted to inhibit PAK activity with reduced anti-PDK1 effect. Two lead compounds were identified based on the ability to inhibit PAK1 activity in an ATP-competitive manner without discernible in vivo PDK1 inhibitory activity in thyroid cancer cell lines. Both compounds reduced thyroid cancer cell viability. Although they are not PAK-specific on a multikinase screening assay, the antimigration activity effect of the compounds in thyroid cancer cells was rescued by overexpression of a constitutively active PAK1, suggesting this activity is involved in this biological effect. CONCLUSIONS We have developed 2 new multikinase inhibitors with anti-PAK activity that may serve as scaffolds for further compound development targeting this progression-related thyroid cancer target.
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Affiliation(s)
- Yihui Ma
- Division of Medicinal Chemistry, College of Pharmacy, The Ohio State University College of Medicine and Wexner Medical Center, Columbus, Ohio 43210, USA
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11
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Eser S, Reiff N, Messer M, Seidler B, Gottschalk K, Dobler M, Hieber M, Arbeiter A, Klein S, Kong B, Michalski CW, Schlitter AM, Esposito I, Kind AJ, Rad L, Schnieke AE, Baccarini M, Alessi DR, Rad R, Schmid RM, Schneider G, Saur D. Selective requirement of PI3K/PDK1 signaling for Kras oncogene-driven pancreatic cell plasticity and cancer. Cancer Cell 2013; 23:406-20. [PMID: 23453624 DOI: 10.1016/j.ccr.2013.01.023] [Citation(s) in RCA: 266] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Revised: 12/27/2012] [Accepted: 01/30/2013] [Indexed: 12/30/2022]
Abstract
Oncogenic Kras activates a plethora of signaling pathways, but our understanding of critical Ras effectors is still very limited. We show that cell-autonomous phosphoinositide 3-kinase (PI3K) and 3-phosphoinositide-dependent protein kinase 1 (PDK1), but not Craf, are key effectors of oncogenic Kras in the pancreas, mediating cell plasticity, acinar-to-ductal metaplasia (ADM), and pancreatic ductal adenocarcinoma (PDAC) formation. This contrasts with Kras-driven non-small cell lung cancer, where signaling via Craf, but not PDK1, is an essential tumor-initiating event. These in vivo genetic studies together with pharmacologic treatment studies in models of human ADM and PDAC demonstrate tissue-specific differences of oncogenic Kras signaling and define PI3K/PDK1 as a suitable target for therapeutic intervention specifically in PDAC.
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Affiliation(s)
- Stefan Eser
- Department of Internal Medicine 2, Technische Universität München, Ismaningerstr. 22, 81675 München, Germany
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12
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Hindie V, Lopez-Garcia LA, Biondi RM. Use of a fluorescent ATP analog to probe the allosteric conformational change in the active site of the protein kinase PDK1. Methods Mol Biol 2013; 928:133-41. [PMID: 22956138 DOI: 10.1007/978-1-62703-008-3_10] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/15/2023]
Abstract
There is growing interest in exploring allosteric sites on proteins for drug discovery. At the center of the regulation of many protein kinases from the AGC family there is an allosteric site termed "PIF-pocket." The regulated binding of a C-terminal region of the kinase to the PIF-pocket, within the small lobe of the catalytic core, modulates the activity of AGC kinases. Small compounds that bind to the PIF-pocket can mimic its physiological mechanism of regulation and modulate the kinase activity in vitro, e.g., small compounds can activate the phosphoinositide-dependent protein kinase 1 (PDK1). Compounds binding to an allosteric site on a protein kinase may produce conformational changes at the ATP-binding site within the active site of the kinase domain. We here describe a fluorescent method using the ATP analog TNP-ATP that allows evaluating the allosteric conformational changes at the ATP-binding site of PDK1 triggered by small compounds binding to the PIF-pocket.
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Affiliation(s)
- Valerie Hindie
- Department of Internal Medicine I, Research Group PhosphoSites, Universitätsklinikum Frankfurt, Frankfurt, Germany
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13
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Baxi SM, Tan W, Murphy ST, Smeal T, Yin MJ. Targeting 3-phosphoinoside-dependent kinase-1 to inhibit insulin-like growth factor-I induced AKT and p70 S6 kinase activation in breast cancer cells. PLoS One 2012; 7:e48402. [PMID: 23119004 PMCID: PMC3485233 DOI: 10.1371/journal.pone.0048402] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2012] [Accepted: 09/25/2012] [Indexed: 12/15/2022] Open
Abstract
Binding of IGF to IGF-IR activates PI3K to generate PIP3 which in turn recruits and activates proteins that contain a pleckstrin homology (PH) domain, including AKT and PDK1. PDK1 is highly expressed in breast tumor samples and breast cancer cell lines. Here we demonstrate that targeting PDK1 with the potent and selective PDK1 inhibitor PF-5177624 in the IGF-PI3K pathway blocks breast cancer cell proliferation and transformation. Breast cancer cell lines MCF7 and T47D, representing the luminal ER positive subtype and harboring PIK3CA mutations, were most responsive to IGF-I induction resulting in upregulated AKT and p70S6K phosphorylation via PDK1 activation. PF-5177624 downregulated AKT and p70S6K phosphorylation, blocked cell cycle progression, and decreased cell proliferation and transformation to block IGFR-I induced activation in breast cancer cells. These results may provide insight into clinical strategies for developing an IGFR-I inhibitor and/or a PDK1 inhibitor in luminal breast cancer patients.
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Affiliation(s)
- Sangita M. Baxi
- Oncology Research, Pfizer Worldwide Research and Development, San Diego, California, United States of America
| | - Wei Tan
- Oncology Research, Pfizer Worldwide Research and Development, San Diego, California, United States of America
| | - Sean T. Murphy
- Medicinal Chemistry, Pfizer Worldwide Research and Development, San Diego, California, United States of America
| | - Tod Smeal
- Oncology Research, Pfizer Worldwide Research and Development, San Diego, California, United States of America
| | - Min-Jean Yin
- Oncology Research, Pfizer Worldwide Research and Development, San Diego, California, United States of America
- * E-mail:
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14
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Kawano Y, Nakae J, Watanabe N, Fujisaka S, Iskandar K, Sekioka R, Hayashi Y, Tobe K, Kasuga M, Noda T, Yoshimura A, Onodera M, Itoh H. Loss of Pdk1-Foxo1 signaling in myeloid cells predisposes to adipose tissue inflammation and insulin resistance. Diabetes 2012; 61:1935-48. [PMID: 22586579 PMCID: PMC3402298 DOI: 10.2337/db11-0770] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Chronic inflammation in adipose tissue contributes to obesity-related insulin resistance. The 3-phosphoinositide-dependent protein kinase 1 (Pdk1)/forkhead transcription factor (Foxo1) pathway is important in regulating glucose and energy homeostasis, but little is known about this pathway in adipose tissue macrophages (ATMs). To investigate this, we generated transgenic mice that carried macrophage/granulocyte-specific mutations, including a Pdk1 knockout (LysMPdk1(-/-)), a Pdk1 knockout with transactivation-defective Foxo1 (Δ256LysMPdk1(-/-)), a constitutively active nuclear (CN) Foxo1 (CNFoxo1(LysM)), or a transactivation-defective Foxo1 (Δ256Foxo1(LysM)). We analyzed glucose metabolism and gene expression in ATM populations isolated with fluorescence-activated cell sorting. The LysMPdk1(-/-) mice exhibited elevated M1 macrophages in adipose tissue and insulin resistance. Overexpression of transactivation-defective Foxo1 rescued these phenotypes. CNFoxo1(LysM) promoted transcription of the C-C motif chemokine receptor 2 (Ccr2) in ATMs and increased M1 macrophages in adipose tissue. On a high-fat diet, CNFoxo1(LysM) mice exhibited insulin resistance. Pdk1 deletion or Foxo1 activation in bone marrow-derived macrophages abolished insulin and interleukin-4 induction of genes involved in alternative macrophage activation. Thus, Pdk1 regulated macrophage infiltration by inhibiting Foxo1-induced Ccr2 expression. This shows that the macrophage Pdk1/Foxo1 pathway is important in regulating insulin sensitivity in vivo.
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Affiliation(s)
- Yoshinaga Kawano
- Frontier Medicine on Metabolic Syndrome, Division of Endocrinology, Metabolism, and Nephrology, Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan
| | - Jun Nakae
- Frontier Medicine on Metabolic Syndrome, Division of Endocrinology, Metabolism, and Nephrology, Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan
- Corresponding author: Jun Nakae,
| | - Nobuyuki Watanabe
- Department of Human Genetics, National Center for Child Health and Development, Tokyo, Japan
| | - Shiho Fujisaka
- Department of Internal Medicine, University of Toyama, Toyama, Japan
| | - Kristy Iskandar
- Pediatric Research Office, Department of Child Health, Faculty of Medicine, Universitas Gadjah Mada, Sardjito Hospital, Yogyakarta, Indonesia
| | - Risa Sekioka
- Frontier Medicine on Metabolic Syndrome, Division of Endocrinology, Metabolism, and Nephrology, Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan
| | - Yoshitake Hayashi
- Division of Molecular Medicine and Medical Genetics, International Center for Medical Research and Treatment, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Kazuyuki Tobe
- Department of Internal Medicine, University of Toyama, Toyama, Japan
| | - Masato Kasuga
- Research Institute, International Medical Center of Japan, Tokyo, Japan
| | - Tetsuo Noda
- Department of Cell Biology, Japanese Foundation for Cancer Research, Cancer Institute, Tokyo, Japan
| | - Akihiko Yoshimura
- Department of Microbiology and Immunology, Keio University School of Medicine, Tokyo, Japan
| | - Masafumi Onodera
- Department of Human Genetics, National Center for Child Health and Development, Tokyo, Japan
| | - Hiroshi Itoh
- Frontier Medicine on Metabolic Syndrome, Division of Endocrinology, Metabolism, and Nephrology, Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan
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15
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Abstract
Protein kinases belonging to the AGC group modulate many diverse cellular processes in all eukaryotes. One important way to regulate AGC kinases is through phosphorylation by the upstream kinase PDK1. PDK1 localization and activity usually depend on interactions with phospholipids, which are mediated by a conserved lipid-binding pleckstrin homology (PH) domain. We recently analyzed putative PDK1 sequences from 17 photosynthetic organisms, finding that PDK1s from vascular and nonvascular species seem to be distinguished by the presence or absence of a PH domain, respectively. The only other reported PDK1 lacking a PH domain is from yeast (Saccharomyces cerevisiae). These observations raise questions about how plant PDK1s and their lipid-binding capabilities have evolved in relation to other eukaryotes, and what this means for PDK1 function. Here we use 100 PDK1 sequences from diverse organisms to discuss possible evolutionary aspects of plant PDK1 structure and lipid binding.
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16
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Pereira MJ, Palming J, Rizell M, Aureliano M, Carvalho E, Svensson MK, Eriksson JW. mTOR inhibition with rapamycin causes impaired insulin signalling and glucose uptake in human subcutaneous and omental adipocytes. Mol Cell Endocrinol 2012; 355:96-105. [PMID: 22333157 DOI: 10.1016/j.mce.2012.01.024] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Revised: 01/17/2012] [Accepted: 01/27/2012] [Indexed: 02/07/2023]
Abstract
Rapamycin is an immunosuppressive agent used after organ transplantation, but its molecular effects on glucose metabolism needs further evaluation. We explored rapamycin effects on glucose uptake and insulin signalling proteins in adipocytes obtained via subcutaneous (n=62) and omental (n=10) fat biopsies in human donors. At therapeutic concentration (0.01 μM) rapamycin reduced basal and insulin-stimulated glucose uptake by 20-30%, after short-term (15 min) or long-term (20 h) culture of subcutaneous (n=23 and n=10) and omental adipocytes (n=6 and n=7). Rapamycin reduced PKB Ser473 and AS160 Thr642 phosphorylation, and IRS2 protein levels in subcutaneous adipocytes. Additionally, it reduced mTOR-raptor, mTOR-rictor and mTOR-Sin1 interactions, suggesting decreased mTORC1 and mTORC2 formation. Rapamycin also reduced IR Tyr1146 and IRS1 Ser307/Ser616/Ser636 phosphorylation, whereas no effects were observed on the insulin stimulated IRS1-Tyr and TSC2 Thr1462 phosphorylation. This is the first study to show that rapamycin reduces glucose uptake in human adipocytes through impaired insulin signalling and this may contribute to the development of insulin resistance associated with rapamycin therapy.
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Affiliation(s)
- Maria J Pereira
- The Lundberg Laboratory for Diabetes Research, Department of Molecular and Clinical Medicine, The Sahlgrenska Academy at University of Gothenburg, 413 45 Gothenburg, Sweden.
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17
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Kim MG, Moon JS, Kim EJ, Lee SH, Oh JW. Destabilization of PDK1 by Hsp90 inactivation suppresses hepatitis C virus replication through inhibition of PRK2-mediated viral RNA polymerase phosphorylation. Biochem Biophys Res Commun 2012; 421:112-8. [PMID: 22490666 DOI: 10.1016/j.bbrc.2012.03.126] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Accepted: 03/27/2012] [Indexed: 12/12/2022]
Abstract
Heat shock protein 90 (Hsp90), which chaperones multiple client proteins, has been shown to be implicated in HCV replication. Pharmacological inhibitors of Hsp90 display an anti-HCV activity. However, little is known about the mechanisms of regulation of HCV replication by Hsp90. Here, we show that Hsp90 inhibition by 17-(dimethylaminoethylamino)-17-demethoxygeldanamycin (17-DMAG) destabilizes phosphoinositide-dependent kinase-1 (PDK1), an upstream kinase of the protein kinase C-related kinase 2 (PRK2) responsible for phosphorylation of HCV RNA polymerase, through the proteosome pathway. Destabilization of PDK1 led to inhibition of phosphorylation of the viral RNA polymerase through a decrease in the abundance of active form PRK2 level. Consequently, Hsp90 inhibition resulted in suppression of HCV replication both in human hepatoma Huh7 cells harboring an HCV subgenomic replicon and in HCV-infected cells. 17-DMAG treatment did not interfere with HCV internal ribosome entry site-mediated translation and the cell cycle in Huh7 cells. Co-treatment of 17-DMAG with interferon-α or HA1077, an inhibitor of PRK2, enhanced the anti-HCV activity of 17-DMAG. Taken together, these findings suggest that Hsp90 plays a critical role in the regulation of HCV RNA polymerase phosphorylation via the PDK1-PRK2 signaling pathway.
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Affiliation(s)
- Mi-Gyeong Kim
- Department of Biotechnology and Translational Research Center for Protein Function Control, Yonsei University, Seoul 120-749, Republic of Korea
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18
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Yang W, AbdulHameed MDM, Hamza A, Zhan CG. New inhibitor of 3-phosphoinositide dependent protein kinase-1 identified from virtual screening. Bioorg Med Chem Lett 2012; 22:1629-32. [PMID: 22266037 PMCID: PMC4371734 DOI: 10.1016/j.bmcl.2011.12.121] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [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: 10/12/2011] [Revised: 12/23/2011] [Accepted: 12/27/2011] [Indexed: 11/16/2022]
Abstract
3-Phosphoinositide-dependent protein kinase-1 (PDK1) has been recognized as a promising anticancer target. Thus, it is interesting to identify new inhibitors of PDK1 for anticancer drug discovery. Through a combined use of virtual screening and wet experimental activity assays, we have identified a new PDK1 inhibitor with IC(50)=~200 nM. The anticancer activities of this compound have been confirmed by the anticancer activity assays using 60 cancer cell lines. The obtained new PDK1 inhibitor and its PDK1-inhibitor binding mode should be valuable in future de novo design of novel, more potent and selective PDK1 inhibitors for future development of anticancer therapeutics.
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Affiliation(s)
- Wenchao Yang
- Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, P. R. China
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, KY 40536
| | - Mohamed Diwan M. AbdulHameed
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, KY 40536
| | - Adel Hamza
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, KY 40536
| | - Chang-Guo Zhan
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, KY 40536
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19
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Abstract
The serine/threonine protein kinase 3-phosphoinositide-dependent protein kinase 1 (PDK1) is a highly conserved eukaryotic kinase that is a central regulator of many AGC kinase subfamily members. Through its regulation of AGC kinases, PDK1 controls many basic cellular processes, from translation to cell survival. While many of these PDK1-regulated processes are conserved across kingdoms, it is not well understood how PDK1 may have evolved within kingdoms. In order to better understand PDK1 evolution within plants, we have isolated and characterized the PDK1 gene from the moss Physcomitrella patens (PpPDK1), a nonvascular representative of early land plants. PpPDK1 is similar to other plant PDK1s in that it can functionally complement a yeast PDK1 knockout line. However, unlike PDK1 from other plants, the P. patens PDK1 protein does not bind phospholipids due to a lack of the lipid-binding pleckstrin homology domain, which is used for lipid-mediated regulation of PDK1 activity. Sequence analysis of several PDK1 proteins suggests that lipid regulation of PDK1 may not commonly occur in algae and nonvascular land plants. PpPDK1 can phosphorylate AGC kinase substrates from tomato (Solanum lycopersicum) and P. patens at the predicted PDK1 phosphorylation site, indicating that the PpPDK1 substrate phosphorylation site is conserved with higher plants. We have also identified residues within the PpPDK1 kinase domain that affect kinase activity and show that a mutant with highly reduced kinase activity can still confer cell viability in both yeast and P. patens. These studies lay the foundation for further analysis of the evolution of PDK1 within plants.
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20
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Aranda-Orgillés B, Rutschow D, Zeller R, Karagiannidis AI, Köhler A, Chen C, Wilson T, Krause S, Roepcke S, Lilley D, Schneider R, Schweiger S. Protein phosphatase 2A (PP2A)-specific ubiquitin ligase MID1 is a sequence-dependent regulator of translation efficiency controlling 3-phosphoinositide-dependent protein kinase-1 (PDPK-1). J Biol Chem 2011; 286:39945-57. [PMID: 21930711 PMCID: PMC3220588 DOI: 10.1074/jbc.m111.224451] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Revised: 09/09/2011] [Indexed: 02/02/2023] Open
Abstract
We have shown previously that the ubiquitin ligase MID1, mutations of which cause the midline malformation Opitz BBB/G syndrome (OS), serves as scaffold for a microtubule-associated protein complex that regulates protein phosphatase 2A (PP2A) activity in a ubiquitin-dependent manner. Here, we show that the MID1 protein complex associates with mRNAs via a purine-rich sequence motif called MIDAS (MID1 association sequence) and thereby increases stability and translational efficiency of these mRNAs. Strikingly, inclusion of multiple copies of the MIDAS motif into mammalian mRNAs increases production of the encoded proteins up to 20-fold. Mutated MID1, as found in OS patients, loses its influence on MIDAS-containing mRNAs, suggesting that the malformations in OS patients could be caused by failures in the regulation of cytoskeleton-bound protein translation. This is supported by the observation that the majority of mRNAs that carry MIDAS motifs is involved in developmental processes and/or energy homeostasis. Further analysis of one of the proteins encoded by a MIDAS-containing mRNA, namely PDPK-1 (3-phosphoinositide dependent protein kinase-1), which is an important regulator of mammalian target of rapamycin/PP2A signaling, showed that PDPK-1 protein synthesis is significantly reduced in cells from an OS patient compared with an age-matched control and can be rescued by functional MID1. Together, our data uncover a novel messenger ribonucleoprotein complex that regulates microtubule-associated protein translation. They suggest a novel mechanism underlying OS and point at an enormous potential of the MIDAS motif to increase the efficiency of biotechnological protein production in mammalian cells.
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Affiliation(s)
| | - Désirée Rutschow
- the Division of Medical Sciences, Ninewells Hospital, University of Dundee, Dundee DD1 9SY, Scotland, United Kingdom
| | - Raphael Zeller
- the Division of Medical Sciences, Ninewells Hospital, University of Dundee, Dundee DD1 9SY, Scotland, United Kingdom
| | - Antonios I. Karagiannidis
- the Institute of Biochemistry, Center of Molecular Biosciences Innsbruck, University of Innsbruck, 6020 Innsbruck, Austria
| | - Andrea Köhler
- the Institute of Biochemistry, Center of Molecular Biosciences Innsbruck, University of Innsbruck, 6020 Innsbruck, Austria
| | - Changwei Chen
- the Division of Medical Sciences, Ninewells Hospital, University of Dundee, Dundee DD1 9SY, Scotland, United Kingdom
| | - Timothy Wilson
- the College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom, and
| | - Sven Krause
- From the Max-Planck Institute for Molecular Genetics, Ihnestrasse 73, 14195 Berlin, Germany
| | - Stefan Roepcke
- From the Max-Planck Institute for Molecular Genetics, Ihnestrasse 73, 14195 Berlin, Germany
| | - David Lilley
- the College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom, and
| | - Rainer Schneider
- From the Max-Planck Institute for Molecular Genetics, Ihnestrasse 73, 14195 Berlin, Germany
- the Institute of Biochemistry, Center of Molecular Biosciences Innsbruck, University of Innsbruck, 6020 Innsbruck, Austria
| | - Susann Schweiger
- From the Max-Planck Institute for Molecular Genetics, Ihnestrasse 73, 14195 Berlin, Germany
- the Division of Medical Sciences, Ninewells Hospital, University of Dundee, Dundee DD1 9SY, Scotland, United Kingdom
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21
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Yu J, Chen KS, Li YN, Yang J, Zhao L. [Inhibition of PDK1 gene expression in esophageal cancer EC9706 cells by RNA interference and its effect on their malignant biological behavior]. Zhonghua Zhong Liu Za Zhi 2011; 33:410-414. [PMID: 21875479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
OBJECTIVE To explore the silencing effects of RNA interference on the expression of 3-phosphoinositide-dependent protein kinase 1 (PDK1) gene, and the effects on malignant phenotypes of esophageal carcinoma EC9706 cells. METHODS PDK1 siRNAs was transfected into the EC9706 cells. The expression of PDK1 mRNA was detected by reverse transcriptase polymerase chain reaction (RT-PCR). At the same time, expressions of PDK1, Akt and phosphorylated Akt proteins were detected by Western blot. Methyl thiazolyl tetrazolium assay (MTT) was used to examine the cell proliferation after transfection. Flow cytometry was used to determine the percentage of apoptosis cells, and Transwell chambers were used to detect the invasion ability of the cells. Tumor formation in nude mice was used to assess the tumorigenic characteristics in vivo. RESULTS Compared with the non-transfected group, PDK1 siRNA effectively inhibited the expression of PDK1 mRNA in EC9706 cells, with an inhibition rate of (28.5 ± 4.2)% at 24 h, (51.1 ± 5.7)% at 48 h and (60.6 ± 4.1)% at 72 h after transfection. The expressions of PDK1 and phosphorylated Akt protein were also knocked down by PDK1 siRNA (P < 0.05). PDK1 siRNA significantly inhibited the cell proliferation and invasion, promoted the cell apoptosis, and inhibited the EC9706 cells proliferation in vivo and the expression of PDK1 protein in the transplanted tumors (P < 0.05). CONCLUSION PDK1 may play an important role in esophageal cancer cell proliferation, invasion and apoptosis, and may serve as an effective target for cancer gene therapy.
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Affiliation(s)
- Jing Yu
- Department of Pathology, The First Affiliated Hospital, Zhengzhou University, China
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22
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Abstract
One goal of aging research is to develop interventions that combat age-related illnesses and slow aging. Although numerous mutations have been shown to achieve this in various model organisms, only a handful of chemicals have been identified to slow aging. Here, we report that celecoxib, a nonsteroidal anti-inflammatory drug widely used to treat pain and inflammation, extends Caenorhabditis elegans lifespan and delays the age-associated physiological changes, such as motor activity decline. Celecoxib also delays the progression of age-related proteotoxicity as well as tumor growth in C. elegans. Celecoxib was originally developed as a potent cyclooxygenase-2 (COX-2) inhibitor. However, the result from a structural-activity analysis demonstrated that the antiaging effect of celecoxib might be independent of its COX-2 inhibitory activity, as analogs of celecoxib that lack COX-2 inhibitory activity produce a similar effect on lifespan. Furthermore, we found that celecoxib acts directly on 3'-phosphoinositide-dependent kinase-1, a component of the insulin/IGF-1 signaling cascade to increase lifespan.
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Affiliation(s)
- Tsui-Ting Ching
- Department of Internal Medicine, Division of Geriatric Medicine, University of Michigan Medical School, Ann Arbor, 48109, USA
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Kakigi R, Naito H, Ogura Y, Kobayashi H, Saga N, Ichinoseki-Sekine N, Yoshihara T, Katamoto S. Heat stress enhances mTOR signaling after resistance exercise in human skeletal muscle. J Physiol Sci 2011; 61:131-40. [PMID: 21222186 PMCID: PMC10717825 DOI: 10.1007/s12576-010-0130-y] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [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: 11/04/2010] [Accepted: 12/26/2010] [Indexed: 12/30/2022]
Abstract
This study investigated the effect of heat stress (HS) on mammalian target of rapamycin (mTOR) signaling involved in translation initiation after resistance exercise in human skeletal muscle. Eight young male subjects performed four sets of six maximal repetitions of knee extension exercises, with or without HS, in a randomized crossover design. HS was applied to the belly of the vastus lateralis by using a microwave therapy unit prior to and during exercise. Muscle biopsies were taken from the vastus lateralis before, immediately after, and 1 h after exercise. HS significantly increased the phosphorylation of Akt/PKB, mTOR, and ribosomal protein S6 at 1 h after exercise (P < 0.05), and the 4E-BP1 phosphorylation level, which had initially decreased with exercise, had recovered by 1 h after exercise with HS. In addition, the phosphorylation of ribosomal S6 kinase 1 was significantly increased immediately after exercise with HS (P < 0.05). These results indicate that HS enhances mTOR signaling after resistance exercise in human skeletal muscle.
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Affiliation(s)
- Ryo Kakigi
- Department of Exercise Physiology, Graduate School of Health and Sports Science, Juntendo University, Inzai, Chiba 270-1695 Japan
| | - Hisashi Naito
- Department of Exercise Physiology, Graduate School of Health and Sports Science, Juntendo University, Inzai, Chiba 270-1695 Japan
- Institute of Health and Sports Science & Medicine, Juntendo University, Inzai, Chiba 270-1695 Japan
| | - Yuji Ogura
- Department of Physiology, St Marianna University School of Medicine, Kawasaki, Kanagawa 216-8511 Japan
| | - Hiroyuki Kobayashi
- Department of Internal Medicine, Mito Medical Center, Tsukuba University Hospital, Mito, Ibaraki 310-0015 Japan
| | - Norio Saga
- Institute of Health and Sports Science & Medicine, Juntendo University, Inzai, Chiba 270-1695 Japan
| | - Noriko Ichinoseki-Sekine
- Institute of Health and Sports Science & Medicine, Juntendo University, Inzai, Chiba 270-1695 Japan
| | - Toshinori Yoshihara
- Department of Exercise Physiology, Graduate School of Health and Sports Science, Juntendo University, Inzai, Chiba 270-1695 Japan
| | - Shizuo Katamoto
- Department of Exercise Physiology, Graduate School of Health and Sports Science, Juntendo University, Inzai, Chiba 270-1695 Japan
- Institute of Health and Sports Science & Medicine, Juntendo University, Inzai, Chiba 270-1695 Japan
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Pollock CB, Yin Y, Yuan H, Zeng X, King S, Li X, Kopelovich L, Albanese C, Glazer RI. PPARδ activation acts cooperatively with 3-phosphoinositide-dependent protein kinase-1 to enhance mammary tumorigenesis. PLoS One 2011; 6:e16215. [PMID: 21297860 PMCID: PMC3020974 DOI: 10.1371/journal.pone.0016215] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Accepted: 12/10/2010] [Indexed: 11/18/2022] Open
Abstract
Peroxisome proliferator-activated receptorδ (PPARδ) is a transcription factor that is associated with metabolic gene regulation and inflammation. It has been implicated in tumor promotion and in the regulation of 3-phosphoinositide-dependent kinase-1 (PDK1). PDK1 is a key regulator of the AGC protein kinase family, which includes the proto-oncogene AKT/PKB implicated in several malignancies, including breast cancer. To assess the role of PDK1 in mammary tumorigenesis and its interaction with PPARδ, transgenic mice were generated in which PDK1 was expressed in mammary epithelium under the control of the MMTV enhancer/promoter region. Transgene expression increased pT308AKT and pS9GSK3β, but did not alter phosphorylation of mTOR, 4EBP1, ribosomal protein S6 and PKCα. The transgenic mammary gland also expressed higher levels of PPARδ and a gene expression profile resembling wild-type mice maintained on a diet containing the PPARδ agonist, GW501516. Both wild-type and transgenic mice treated with GW501516 exhibited accelerated rates of tumor formation that were more pronounced in transgenic animals. GW501516 treatment was accompanied by a distinct metabolic gene expression and metabolomic signature that was not present in untreated animals. GW501516-treated transgenic mice expressed higher levels of fatty acid and phospholipid metabolites than treated wild-type mice, suggesting the involvement of PDK1 in enhancing PPARδ-driven energy metabolism. These results reveal that PPARδ activation elicits a distinct metabolic and metabolomic profile in tumors that is in part related to PDK1 and AKT signaling.
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Affiliation(s)
- Claire B. Pollock
- Department of Oncology and Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, D.C., United States of America
| | - Yuzhi Yin
- Department of Oncology and Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, D.C., United States of America
| | - Hongyan Yuan
- Department of Oncology and Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, D.C., United States of America
| | - Xiao Zeng
- Department of Oncology and Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, D.C., United States of America
| | - Sruthi King
- Department of Pharmacology, Georgetown University Medical Center, Washington, D.C., United States of America
| | - Xin Li
- Department of Biostatistics, Bioinformatics and Biomathematics, Georgetown University Medical Center, Washington, D.C., United States of America
| | - Levy Kopelovich
- Chemoprevention Agent Development and Research Group, Division of Cancer Prevention, National Cancer Institute, Bethesda, Maryland, United States of America
| | - Chris Albanese
- Department of Oncology and Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, D.C., United States of America
| | - Robert I. Glazer
- Department of Oncology and Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, D.C., United States of America
- * E-mail:
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Matsui H, Miyao A, Takahashi A, Hirochika H. Pdk1 kinase regulates basal disease resistance through the OsOxi1-OsPti1a phosphorylation cascade in rice. Plant Cell Physiol 2010; 51:2082-2091. [PMID: 21051443 DOI: 10.1093/pcp/pcq167] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The AGC kinase OsOxi1, which has been isolated as an interactor with OsPti1a, positively regulates basal disease resistance in rice. In eukaryotes, AGC kinase family proteins are regulated by 3-phosphoinositide-dependent protein kinase 1 (Pdk1). In Arabidopsis, AtPdk1 directly interacts with phosphatidic acid, which functions as a second messenger in both biotic and abiotic stress responses. However, the functions of Pdk1 are poorly understood in plants. We show here that OsPdk1 acts upstream of the OsOxi1-OsPti1a signal cascade in disease resistance in rice. OsPdk1 interacts with OsOxi1 and phosphorylates the Ser283 residue of OsOxi1 in vitro. To investigate whether OsPdk1 is involved in immunity that is triggered by microbial-associated molecular patterns, we analyzed the phosphorylation status of OsPdk1 in response to chitin elicitor. Like OsOxi1, OsPdk1 is rapidly phosphorylated in response to chitin elicitor, suggesting that OsPdk1 participates in signal transduction through pathogen recognition. The overexpression of OsPdk1 enhanced basal resistance against a blast fungus, Magnaporthe oryzae, and a bacterial pathogen, Xanthomonas oryzae pv. oryzae (Xoo). Taken together, these results suggest that OsPdk1 positively regulates basal disease resistance through the OsOxi1-OsPti1a phosphorylation cascade in rice.
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Affiliation(s)
- Hidenori Matsui
- Division of Plant Sciences, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, 305-8602 Japan
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26
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Di RM, Feng QT, Chang Z, Luan Q, Zhang YY, Huang J, Li XL, Yang ZZ. PDK1 plays a critical role in regulating cardiac function in mice and human. Chin Med J (Engl) 2010; 123:2358-2363. [PMID: 21034549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023] Open
Abstract
BACKGROUND PDK1 is an essential protein kinase that plays a critical role in mammalian development. Mouse lacking PDK1 leads to multiple abnormalities and embryonic lethality at E9.5. To elucidate the role of PDK1 in the heart, we investigated the cardiac phenotype of mice that lack PDK1 in the heart in different growth periods and the alteration of PDK1 signaling in human failing heart. METHODS We employed Cre/loxP system to generate PDK1(flox/flox): α-MHC-Cre mice, which specifically deleted PDK1 in cardiac muscle at birth, and tamoxifen-inducible heart-specific PDK1 knockout mice (PDK1(flox/flox):MerCreMer mice), in which PDK1 was deleted in myocardium in response to the treatment with tamoxifen. Transmural myocardial tissues from human failing hearts and normal hearts were sampled from the left ventricular apex to analyze the activity of PDK1/Akt signaling pathways by Western blotting. RESULTS PDK1(flox/flox): α-MHC-Cre mice died of heart failure at 5 and 10 weeks old. PDK1(flox/flox) -MerCreMer mice died of heart failure from 5 to 21 weeks after the initiation of tamoxifen treatment at 8 weeks old. We found that expression levels of PDK1 in human failing heart tissues were significantly decreased compared with control hearts. CONCLUSION Our results suggest that PDK1 signaling network takes part in regulating cardiac viability and function in mice, and may be also involved in human heart failure disease.
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Affiliation(s)
- Ruo-min Di
- Department of Cardiology, First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, China
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Ek-Ramos MJ, Avila J, Cheng C, Martin GB, Devarenne TP. The T-loop extension of the tomato protein kinase AvrPto-dependent Pto-interacting protein 3 (Adi3) directs nuclear localization for suppression of plant cell death. J Biol Chem 2010; 285:17584-94. [PMID: 20371603 PMCID: PMC2878523 DOI: 10.1074/jbc.m110.117416] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [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: 02/23/2010] [Revised: 04/05/2010] [Indexed: 02/02/2023] Open
Abstract
In tomato (Solanum lycopersicum), resistance to Pseudomonas syringae pv. tomato is elicited by the interaction of the host Pto kinase with the pathogen effector protein AvrPto, which leads to various immune responses including localized cell death termed the hypersensitive response. The AGC kinase Adi3 functions to suppress host cell death and interacts with Pto only in the presence of AvrPto. The cell death suppression (CDS) activity of Adi3 requires phosphorylation by 3-phosphoinositide-dependent protein kinase 1 (Pdk1) and loss of Adi3 function is associated with the hypersensitive response cell death initiated by the Pto/AvrPto interaction. Here we studied the relationship between Adi3 cellular localization and its CDS activity. Adi3 is a nuclear-localized protein, and this localization is dictated by a nuclear localization signal found in the Adi3 T-loop extension, an approximately 80 amino acid insertion into the T-loop, or activation loop, which is phosphorylated for kinase activation. Nuclear localization of Adi3 is required for its CDS activity and loss of nuclear localization causes elimination of Adi3 CDS activity and induction of cell death. This nuclear localization of Adi3 is dependent on Ser-539 phosphorylation by Pdk1 and non-nuclear Adi3 is found in punctate structures throughout the cell. Our data support a model in which Pdk1 phosphorylation of Adi3 directs nuclear localization for CDS and that disruption of Adi3 nuclear localization may be a mechanism for induction of cell death such as that during the Pto/AvrPto interaction.
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Affiliation(s)
- María J. Ek-Ramos
- From the Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843
| | - Julian Avila
- From the Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843
| | - Cheng Cheng
- From the Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843
| | - Gregory B. Martin
- the Boyce Thompson Institute for Plant Research, Ithaca, New York 14853, and
- the Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, New York 14853
| | - Timothy P. Devarenne
- From the Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843
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28
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Sozopoulos E, Litsiou H, Voutsinas G, Mitsiades N, Anagnostakis N, Tseva T, Patsouris E, Tseleni-Balafouta S. Mutational and immunohistochemical study of the PI3K/Akt pathway in papillary thyroid carcinoma in Greece. Endocr Pathol 2010; 21:90-100. [PMID: 20186503 DOI: 10.1007/s12022-010-9112-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PI3K/Akt signaling pathway plays critical role in many cell processes. There is indication that enhanced activation of PI3K/Akt cascade is implicated in thyroid tumors. Aim of this study was to evaluate the mutational status and expression of PI3K/Akt pathway mediators in papillary thyroid carcinoma in Greece. We evaluated the presence of mutations in PIK3CA (exons 9 and 20), AKT1 (exons 6-11), AKT2 (exons 6-11), AKT3 (exons 5-10), PTEN (exons 3-8), and PDPK1 (exons 4-10) genes in 83 papillary thyroid carcinomas by DNA sequencing. The expression levels of phospho-Akt and insulin-like growth factor I receptor (IGF-IR) were evaluated by immunohistochemistry. PIK3CA mutations were found in three samples. The analysis of AKT1 revealed one silent mutation in exon 9 (G726A) in 16 samples. One specimen carried an AKT3 mutation. One missense mutation was found in one sample in PTEN. No mutations were found in AKT2 and PDPK1. Increased levels of phosphorylated total Akt and IGF-IR were identified in some papillary cancers. Our findings indicate that PI3K/Akt signaling pathway is activated in some papillary tumors. However, mutations in genes coding most mediators of the pathway have not been proven to be the major modus of enhanced activation. These data suggest a potential role for PI3K/Akt-mediated signaling in papillary thyroid tumors.
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Affiliation(s)
- Elias Sozopoulos
- 1st Department of Pathology, Medical School, University of Athens, M. Asias 75, Athens, 11527, Greece.
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29
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Gupta NA, Mells J, Dunham RM, Grakoui A, Handy J, Saxena NK, Anania FA. Glucagon-like peptide-1 receptor is present on human hepatocytes and has a direct role in decreasing hepatic steatosis in vitro by modulating elements of the insulin signaling pathway. Hepatology 2010; 51:1584-92. [PMID: 20225248 PMCID: PMC2862093 DOI: 10.1002/hep.23569] [Citation(s) in RCA: 355] [Impact Index Per Article: 25.4] [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] [Indexed: 12/13/2022]
Abstract
UNLABELLED Glucagon-like peptide 1 (GLP-1) is a naturally occurring peptide secreted by the L cells of the small intestine. GLP-1 functions as an incretin and stimulates glucose-mediated insulin production by pancreatic beta cells. In this study, we demonstrate that exendin-4/GLP-1 has a cognate receptor on human hepatocytes and that exendin-4 has a direct effect on the reduction of hepatic steatosis in the absence of insulin. Both glucagon-like peptide 1 receptor (GLP/R) messenger RNA and protein were detected on primary human hepatocytes, and receptor was internalized in the presence of GLP-1. Exendin-4 increased the phosphorylation of 3-phosphoinositide-dependent kinase-1 (PDK-1), AKT, and protein kinase C zeta (PKC-zeta) in HepG2 and Huh7 cells. Small interfering RNA against GLP-1R abolished the effects on PDK-1 and PKC-zeta. Treatment with exendin-4 quantitatively reduced triglyceride stores compared with control-treated cells. CONCLUSION This is the first report that the G protein-coupled receptor GLP-1R is present on human hepatocytes. Furthermore, it appears that exendin-4 has the same beneficial effects in vitro as those seen in our previously published in vivo study in ob/ob mice, directly reducing hepatocyte steatosis. Future use for human nonalcoholic fatty liver disease, either in combination with dietary manipulation or other pharmacotherapy, may be a significant advance in treatment of this common form of liver disease.
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Affiliation(s)
- Nitika Arora Gupta
- Department of Pediatrics, Emory University School of Medicine
- Children’s Healthcare of Atlanta, Transplant services
| | - Jamie Mells
- Nutrition and Health Sciences Program, Graduate Division of Biological and Biomedical Sciences
| | - Richard M. Dunham
- Department of Medicine, Division of Infectious Diseases, Microbiology and Immunology, Emory Vaccine Center
| | - Arash Grakoui
- Department of Medicine, Division of Infectious Diseases, Microbiology and Immunology, Emory Vaccine Center
| | - Jeffrey Handy
- Division of Digestive Diseases, Emory University School of Medicine
| | | | - Frank A. Anania
- Division of Digestive Diseases, Emory University School of Medicine
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Sanchez Canedo C, Demeulder B, Ginion A, Bayascas JR, Balligand JL, Alessi DR, Vanoverschelde JL, Beauloye C, Hue L, Bertrand L. Activation of the cardiac mTOR/p70(S6K) pathway by leucine requires PDK1 and correlates with PRAS40 phosphorylation. Am J Physiol Endocrinol Metab 2010; 298:E761-9. [PMID: 20051528 DOI: 10.1152/ajpendo.00421.2009] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Like insulin, leucine stimulates the mammalian target of rapamycin (mTOR)/p70 ribosomal S6 kinase (p70(S6K)) axis in various organs. Insulin proceeds via the canonical association of phosphatidylinositol 3-kinase (PI3K), phosphoinositide-dependent protein kinase-1 (PDK1), and protein kinase B (PKB/Akt). The signaling involved in leucine effect, although known to implicate a PI3K mechanism independent of PKB/Akt, is more poorly understood. In this study, we investigated whether PDK1 could also participate in the events leading to mTOR/p70(S6K) activation in response to leucine in the heart. In wild-type hearts, both leucine and insulin increased p70(S6K) activity whereas, in contrast to insulin, leucine was unable to activate PKB/Akt. The changes in p70(S6K) activity induced by insulin and leucine correlated with changes in phosphorylation of Thr(389), the mTOR phosphorylation site on p70(S6K), and of Ser(2448) on mTOR, both related to mTOR activity. Leucine also triggered phosphorylation of the proline-rich Akt/PKB substrate of 40 kDa (PRAS40), a new pivotal mTOR regulator. In PDK1 knockout hearts, leucine, similarly to insulin, failed to induce the phosphorylation of mTOR and p70(S6K), leading to the absence of p70(S6K) activation. The loss of leucine effect in absence of PDK1 correlated with the lack of PRAS40 phosphorylation. Moreover, the introduction in PDK1 of the L155E mutation, which is known to preserve the insulin-induced and PKB/Akt-dependent phosphorylation of mTOR/p70(S6K), suppressed all leucine effects, including phosphorylation of mTOR, PRAS40, and p70(S6K). We conclude that the leucine-induced stimulation of the cardiac PRAS40/mTOR/p70(S6K) pathway requires PDK1 in a way that differs from that of insulin.
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Iskandar K, Cao Y, Hayashi Y, Nakata M, Takano E, Yada T, Zhang C, Ogawa W, Oki M, Chua S, Itoh H, Noda T, Kasuga M, Nakae J. PDK-1/FoxO1 pathway in POMC neurons regulates Pomc expression and food intake. Am J Physiol Endocrinol Metab 2010; 298:E787-98. [PMID: 20103739 DOI: 10.1152/ajpendo.00512.2009] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Both insulin and leptin signaling converge on phosphatidylinositol 3-OH kinase [PI(3)K]/3-phosphoinositide-dependent protein kinase-1 (PDK-1)/protein kinase B (PKB, also known as Akt) in proopiomelanocortin (POMC) neurons. Forkhead box-containing protein-O1 (FoxO1) is inactivated in a PI(3)K-dependent manner. However, the interrelationship between PI(3)K/PDK-1/Akt and FoxO1, and the chronic effects of the overexpression of FoxO1 in POMC neurons on energy homeostasis has not been elucidated. To determine the extent to which PDK-1 and FoxO1 signaling in POMC neurons was responsible for energy homeostasis, we generated POMC neuron-specific Pdk1 knockout mice (POMCPdk1(-/-)) and mice selectively expressing a constitutively nuclear (CN)FoxO1 or transactivation-defective (Delta256)FoxO1 in POMC neurons (CNFoxO1(POMC) or Delta256FoxO1(POMC)). POMCPdk1(-/-) mice showed increased food intake and body weight accompanied by decreased expression of Pomc gene. The CNFoxO1(POMC) mice exhibited mild obesity and hyperphagia compared with POMCPdk1(-/-) mice. Although expression of the CNFoxO1 made POMCPdk1(-/-) mice more obese due to excessive suppression of Pomc gene, overexpression of Delta256FoxO1 in POMC neurons had no effects on metabolic phenotypes and Pomc expression levels of POMCPdk1(-/-) mice. These data suggest a requirement for PDK-1 and FoxO1 in transcriptional regulation of Pomc and food intake.
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Affiliation(s)
- Kristy Iskandar
- International Center for Medical Research and Treatment, Kobe University Graduate school of Medicine, Japan
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Lu Z, Cox-Hipkin MA, Windsor WT, Boyapati A. 3-Phosphoinositide–Dependent Protein Kinase-1 Regulates Proliferation and Survival of Cancer Cells with an Activated Mitogen-Activated Protein Kinase Pathway. Mol Cancer Res 2010; 8:421-32. [PMID: 20197379 DOI: 10.1158/1541-7786.mcr-09-0179] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Zhuomei Lu
- Schering-Plough Research Institute, Kenilworth, NJ 07033, USA
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Xu Z, Nagashima K, Sun D, Rush T, Northrup A, Andersen JN, Kariv I, Bobkova EV. Development of high-throughput TR-FRET and AlphaScreen assays for identification of potent inhibitors of PDK1. ACTA ACUST UNITED AC 2010; 14:1257-62. [PMID: 19822882 DOI: 10.1177/1087057109349356] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The PI3K/Akt signaling pathway plays a key role in cancer cell growth, survival, and tumor angiogenesis. 3-Phosphoinositide-dependent protein kinase 1 (PDK1) is a Ser/Thr protein kinase, which catalyzes the phosphorylation of a conserved residue in the activation loop of a number of AGC kinases, including proto-oncogenes Akt, p70S6K, and RSK kinases. To find new small-molecule inhibitors of this important regulator kinase, the authors have developed PDK1-specific high-throughput enzymatic assays in time-resolved fluorescence resonance energy transfer (TR-FRET) and AlphaScreen formats, monitoring phosphorylation of a biotinylated peptide substrate derived from the activation loop of Akt. Development of homogeneous assays enabled screening of a focused kinase library of approximately 21,500 compounds in 1536-well TR-FRET format in duplicate. Upon validation of hits in an alternative 384-well AlphaScreen assay, several classes of structurally diverse PDK1 inhibitors, including tetracyclics, tricyclics, azaindoles, indazoles, and indenylpyrazoles, were identified, thus confirming the utility and sensitivity of the developed assays. Further testing in PC3 prostate cancer cells confirmed that representatives of the tetracyclic series showed intracellular modulation of the PDK1 activity, as evident from decreased phosphorylation levels of AKT, RSK, and S6-ribosomal protein.
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Affiliation(s)
- Zangwei Xu
- Merck Research Laboratories, Boston, Massachusetts 02115, USA
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Bouallegue A, Pandey NR, Srivastava AK. CaMKII knockdown attenuates H2O2-induced phosphorylation of ERK1/2, PKB/Akt, and IGF-1R in vascular smooth muscle cells. Free Radic Biol Med 2009; 47:858-66. [PMID: 19545622 DOI: 10.1016/j.freeradbiomed.2009.06.022] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2008] [Revised: 05/19/2009] [Accepted: 06/18/2009] [Indexed: 12/23/2022]
Abstract
We have shown earlier a requirement for Ca(2+) and calmodulin (CaM) in the H(2)O(2)-induced activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2) and protein kinase B (PKB), key mediators of growth-promoting, proliferative, and hypertrophic responses in vascular smooth muscle cells (VSMC). Because the effect of CaM is mediated through CaM-dependent protein kinase II (CaMKII), we have investigated here the potential role of CaMKII in H(2)O(2)-induced ERK1/2 and PKB phosphorylation by using pharmacological inhibitors of CaM and CaMKII, a CaMKII inhibitor peptide, and siRNA knockdown strategies for CaMKII alpha. Calmidazolium and W-7, antagonists of CaM, as well as KN-93, a specific inhibitor of CaMKII, attenuated H(2)O(2)-induced responses of ERK1/2 and PKB phosphorylation in a dose-dependent fashion. Similar to H(2)O(2), calmidazolium and KN-93 also exhibited an inhibitory effect on glucose/glucose oxidase-induced phosphorylation of ERK1/2 and PKB in these cells. Transfection of VSMC with CaMKII autoinhibitory peptide corresponding to the autoinhibitory domain (aa 281-309) of CaMKII and with siRNA of CaMKII alpha attenuated the H(2)O(2)-induced phosphorylation of ERK1/2 and PKB. In addition, calmidazolium and KN-93 blocked H(2)O(2)-induced Pyk2 and insulin-like growth factor-1 receptor (IGF-1R) phosphorylation. Moreover, treatment of VSMC with CaMKII alpha siRNA abolished the H(2)O(2)-induced IGF-1R phosphorylation. H(2)O(2) treatment also induced Thr(286) phosphorylation of CaMKII, which was inhibited by both calmidazolium and KN-93. These results demonstrate that CaMKII plays a critical upstream role in mediating the effects of H(2)O(2) on ERK1/2, PKB, and IGF-1R phosphorylation.
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Affiliation(s)
- Ali Bouallegue
- Laboratory of Cell Signaling, Montreal Diabetes Research Centre, Centre de Recherche, Centre Hospitalier de l'Université de Montréal, Technopole Angus Campus, Montreal, Canada
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Simpson GL, Hughes JA, Washio Y, Bertrand SM. Direct small-molecule kinase activation: Novel approaches for a new era of drug discovery. Curr Opin Drug Discov Devel 2009; 12:585-596. [PMID: 19736618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The pharmaceutical industry has traditionally targeted the inhibition of dysregulated kinases to treat diseases such as cancer and inflammatory disorders. In contrast to the human genome sequencing project, which aimed to identify novel biological targets, the possibility of activating kinases uses known targets in a novel manner. In an approach that is similar to other target classes (eg, GPCRs and nuclear receptors), transient upregulation of kinase function using small molecules has been increasingly demonstrated to lead to favorable disease outcomes. This review discusses direct small-molecule kinase activators: specifically, how these molecules were discovered, characterized, evaluated and developed into drug leads. The choice of potential targets, the mechanisms of activation and the common strategies used to discover activators are also highlighted.
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Affiliation(s)
- Graham L Simpson
- GlaxoSmithKline plc, GSK Medicines Research Centre, Stevenage, Hertfordshire, UK.
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36
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Arkin MR, Whitty A. The road less traveled: modulating signal transduction enzymes by inhibiting their protein-protein interactions. Curr Opin Chem Biol 2009; 13:284-90. [PMID: 19553156 DOI: 10.1016/j.cbpa.2009.05.125] [Citation(s) in RCA: 135] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2009] [Revised: 05/13/2009] [Accepted: 05/18/2009] [Indexed: 12/23/2022]
Abstract
The biological functions of intracellular signaling enzymes typically depend on multiple protein-protein interactions (PPI) with substrates, scaffolding proteins, and other cytoplasmic molecules. Blocking these interactions provides an alternative means to modulate signaling activity without fully ablating the catalytic activity of the target. Several recent reports describe small-molecule antagonists that target PPI sites on signaling enzymes. These findings suggest that such sites may often be druggable. However, the hypothesis that targeting such sites might confer on the resulting inhibitors improved properties of efficacy and/or tolerability, while appealing, remains largely untested.
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Affiliation(s)
- Michelle R Arkin
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, CA 94158, United States.
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Xia S, Chen Z, Forman LW, Faller DV. PKCdelta survival signaling in cells containing an activated p21Ras protein requires PDK1. Cell Signal 2009; 21:502-8. [PMID: 19146951 PMCID: PMC2644428 DOI: 10.1016/j.cellsig.2008.12.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [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: 10/28/2008] [Revised: 12/01/2008] [Accepted: 12/02/2008] [Indexed: 01/02/2023]
Abstract
Protein kinase C delta (PKCdelta) modulates cell survival and apoptosis in diverse cellular systems. We recently reported that PKCdelta functions as a critical anti-apoptotic signal transducer in cells containing activated p21(Ras) and results in the activation of AKT, thereby promoting cell survival. How PKCdelta is regulated by p21(Ras), however, remains incompletely understood. In this study, we show that PKCdelta, as a transducer of anti-apoptotic signals, is activated by phosphotidylinositol 3' kinase/phosphoinositide-dependent kinase 1 (PI(3)K-PDK1) to deliver the survival signal to Akt in the environment of activated p21(Ras). PDK1 is upregulated in cells containing an activated p21Ras. Knock-down of PDK1, PKCdelta, or AKT forces cells containing activated p21(Ras) to undergo apoptosis. PDK1 regulates PKCdelta activity, and constitutive expression of PDK1 increases PKCdelta activity in different cell types. Conversely, expression of a kinase-dead (dominant-negative) PDK1 significantly suppresses PKCdelta activity. p21(Ras)-mediated survival signaling is therefore regulated by via a PI(3)K-AKT pathway, which is dependent upon both PDK1 and PKCdelta, and PDK1 activates and regulates PKCdelta to determine the fate of cells containing a mutated, activated p21(Ras).
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Affiliation(s)
- Shuhua Xia
- Cancer Research Canter, Boston University School of Medicine, Boston, Massachusetts 02118, USA
| | - Zhihong Chen
- Cancer Research Canter, Boston University School of Medicine, Boston, Massachusetts 02118, USA
| | - Lora W. Forman
- Cancer Research Canter, Boston University School of Medicine, Boston, Massachusetts 02118, USA
| | - Douglas V. Faller
- Cancer Research Canter, Boston University School of Medicine, Boston, Massachusetts 02118, USA
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Calleja V, Laguerre M, Parker PJ, Larijani B. Role of a novel PH-kinase domain interface in PKB/Akt regulation: structural mechanism for allosteric inhibition. PLoS Biol 2009; 7:e17. [PMID: 19166270 PMCID: PMC2628406 DOI: 10.1371/journal.pbio.1000017] [Citation(s) in RCA: 192] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2008] [Accepted: 12/05/2008] [Indexed: 11/19/2022] Open
Abstract
Protein kinase B (PKB/Akt) belongs to the AGC superfamily of related serine/threonine protein kinases. It is a key regulator downstream of various growth factors and hormones and is involved in malignant transformation and chemo-resistance. Full-length PKB protein has not been crystallised, thus studying the molecular mechanisms that are involved in its regulation in relation to its structure have not been simple. Recently, the dynamics between the inactive and active conformer at the molecular level have been described. The maintenance of PKB's inactive state via the interaction of the PH and kinase domains prevents its activation loop to be phosphorylated by its upstream activator, phosphoinositide-dependent protein kinase-1 (PDK1). By using a multidisciplinary approach including molecular modelling, classical biochemical assays, and Förster resonance energy transfer (FRET)/two-photon fluorescence lifetime imaging microscopy (FLIM), a detailed model depicting the interaction between the different domains of PKB in its inactive conformation was demonstrated. These findings in turn clarified the molecular mechanism of PKB inhibition by AKT inhibitor VIII (a specific allosteric inhibitor) and illustrated at the molecular level its selectivity towards different PKB isoforms. Furthermore, these findings allude to the possible function of the C-terminus in sustaining the inactive conformer of PKB. This study presents essential insights into the quaternary structure of PKB in its inactive conformation. An understanding of PKB structure in relation to its function is critical for elucidating its mode of activation and discovering how to modulate its activity. The molecular mechanism of inhibition of PKB activation by the specific drug AKT inhibitor VIII has critical implications for determining the mechanism of inhibition of other allosteric inhibitors and for opening up opportunities for the design of new generations of modulator drugs.
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Affiliation(s)
- Véronique Calleja
- Cell Biophysics Laboratory, Cancer Research UK, Lincoln's Inn Fields Laboratories, London Research Institute, London, United Kingdom
- * To whom correspondence should be addressed. E-mail: (BL); (VC)
| | - Michel Laguerre
- UMR 5248-CNRS, Institut Européen de Chimie et Biologie, Pessac, France
| | - Peter J Parker
- Protein Phosphorylation Laboratory, Cancer Research UK, Lincoln's Inn Fields Laboratories, London Research Institute, London, United Kingdom
- Division of Cancer Studies KCL, Guy's Hospital, London, United Kingdom
| | - Banafshé Larijani
- Cell Biophysics Laboratory, Cancer Research UK, Lincoln's Inn Fields Laboratories, London Research Institute, London, United Kingdom
- * To whom correspondence should be addressed. E-mail: (BL); (VC)
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Mukherji A, Janbandhu VC, Kumar V. HBx protein modulates PI3K/Akt pathway to overcome genotoxic stress-induced destabilization of cyclin D1 and arrest of cell cycle. Indian J Biochem Biophys 2009; 46:37-44. [PMID: 19374252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Growth arrest represents an innate barrier to carcinogenesis. DNA damage and replicational stress are known to induce growth arrest and apoptotic death to avert genomic instability and consequently carcinogenesis. In this study, working on the genotoxic stress induced by hydroxyurea and methylmethanesulfone, we observed a growth arrest at G1/S-phase that was mediated by destabilization of cyclin D1. The growth arrest was independent of the stability of cdc25A and preceded transcriptional up-regulation of p21(waf1). Cyclin D1 destabilization involved its phosphorylation by GSK-3beta at threonine-286, since overexpression of the kinase-dead mutant of GSK-3beta or cyclin D1T(286A) Inutant conferred stability to cyclin D1. Further, overexpression of cyclin D1(T286A) also helped in bypassing G1/S phase growth arrest. We also observed a rapid inactivation of Akt/PKB kinase in the presence of hydroxyurea. Enforced expression of the constitutively active Akt or viral oncoprotein HBx (Hepatitis B virus X protein) was sufficient to overcome growth arrest, independent of ATR signaling and stabilized cyclin D1. Thus, the present work not only establishes cyclin D1 to be a novel mediator of genotoxic stress signaling, but also explains how a deregulated mitogenic signaling or a viral oncoprotein can help bypass growth arrest.
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Affiliation(s)
- A Mukherji
- Virology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110067, India
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El Ouaamari A, Baroukh N, Martens GA, Lebrun P, Pipeleers D, van Obberghen E. miR-375 targets 3'-phosphoinositide-dependent protein kinase-1 and regulates glucose-induced biological responses in pancreatic beta-cells. Diabetes 2008; 57:2708-17. [PMID: 18591395 PMCID: PMC2551681 DOI: 10.2337/db07-1614] [Citation(s) in RCA: 348] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
OBJECTIVE MicroRNAs are short, noncoding RNAs that regulate gene expression. We hypothesized that the phosphatidylinositol 3-kinase (PI 3-kinase) cascade known to be important in beta-cell physiology could be regulated by microRNAs. Here, we focused on the pancreas-specific miR-375 as a potential regulator of its predicted target 3'-phosphoinositide-dependent protein kinase-1 (PDK1), and we analyzed its implication in the response of insulin-producing cells to elevation of glucose levels. RESEARCH DESIGN AND METHODS We used insulinoma-1E cells to analyze the effects of miR-375 on PDK1 protein level and downstream signaling using Western blotting, glucose-induced insulin gene expression using quantitative RT-PCR, and DNA synthesis by measuring thymidine incorporation. Moreover, we analyzed the effect of glucose on miR-375 expression in both INS-1E cells and primary rat islets. Finally, miR-375 expression in isolated islets was analyzed in diabetic Goto-Kakizaki (GK) rats. RESULTS We found that miR-375 directly targets PDK1 and reduces its protein level, resulting in decreased glucose-stimulatory action on insulin gene expression and DNA synthesis. Furthermore, glucose leads to a decrease in miR-375 precursor level and a concomitant increase in PDK1 protein. Importantly, regulation of miR-375 expression by glucose occurs in primary rat islets as well. Finally, miR-375 expression was found to be decreased in fed diabetic GK rat islets. CONCLUSIONS Our findings provide evidence for a role of a pancreatic-specific microRNA, miR-375, in the regulation of PDK1, a key molecule in PI 3-kinase signaling in pancreatic beta-cells. The effects of glucose on miR-375 are compatible with the idea that miR-375 is involved in glucose regulation of insulin gene expression and beta-cell growth.
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Takeda A, Kido Y, Hashimoto N, Noda T, Kasuga M. Pancreatic beta cell mass preserved in heterozygous PDK1 knockout mice. Kobe J Med Sci 2008; 54:E183-E190. [PMID: 19246967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We have demonstrated that 3-phosphoinositide-dependent protein kinase 1 (PDK1) contributes to signaling by insulin or insulin-like growth factor-1 (IGF-1) that is responsible for the regulation of both the number and size of pancreatic beta cells in mice. Complete ablation of PDK1 in pancreatic beta cells leads to progressive hyperglycemia as a result of loss of beta cell mass. In this study, we generated heterozygous pancreatic beta cell-specific PDK1 knockout (betaPDK1+/-) mice and fed them a high-fat diet as a model of human type 2 diabetes. The betaPDK1+/- mice exhibited normal glucose tolerance even on a high-fat diet. Further, islet morphology and beta cell mass were normal in betaPDK1+/- mice, and haploinsufficiency of PDK1 did not impair the compensatory hyperplasia of beta cells on a high-fat diet. The phosphorylation and expression of the molecules that are expressed downstream of PDK1 were similar in the islets of the betaPDK1+/- and control mice. Eventually, we concluded that glucose homeostasis and islet mass were maintained in betaPDK1+/- mice.
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Affiliation(s)
- Akihiko Takeda
- Department of Internal Medicine, Division of Diabetes, Metabolism, and Endocrinology, Kobe University Graduate School of Medicine, Kobe 17, Japan
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Misra UK, Kaczowka S, Pizzo SV. The cAMP-activated GTP exchange factor, Epac1 upregulates plasma membrane and nuclear Akt kinase activities in 8-CPT-2-O-Me-cAMP-stimulated macrophages: Gene silencing of the cAMP-activated GTP exchange Epac1 prevents 8-CPT-2-O-Me-cAMP activation of Akt activity in macrophages. Cell Signal 2008; 20:1459-70. [PMID: 18495429 PMCID: PMC2519236 DOI: 10.1016/j.cellsig.2008.04.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [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: 09/19/2007] [Revised: 03/11/2008] [Accepted: 04/01/2008] [Indexed: 11/16/2022]
Abstract
cAMP regulates a wide range of processes through its downstream effectors including PKA, and the family of guanine nucleotide exchange factors. Depending on the cell type, cAMP inhibits or stimulates growth and proliferation in a PKA-dependent or independent manner. PKA-independent effects are mediated by PI 3-kinases-Akt signaling and EPAC1 (exchange protein directly activated by cAMP) activation. Recently, we reported PKA-independent activation of the protein kinase Akt as well co-immunoprecipitation of Epac1 with Rap1, p-Akt(Thr-308), and p-Akt(Ser-473) in forskolin-stimulated macrophages. To further probe the role of Epac1 in Akt protein kinase activation and cellular proliferation, we employed the cAMP analog 8-CPT-2-O-Me-cAMP, which selectively binds to Epac1 and triggers Epac1 signaling. We show the association of Epac1 with activated Akt kinases by co-immunoprecipitation and GST-pulldown assays. Silencing Epac1 gene expression by RNA interference significantly reduced levels of Epac1 mRNA, Epac protein, Rap1 GTP, p-ERK1/2, p-B-Raf, p110alpha catalytic subunit of PI 3-kinase, p-PDK, and p-p(70s6k). Silencing Epac1 gene expression by RNA interference also suppressed 8-CPT-2-O-Me-cAMP-upregulated protein and DNA synthesis. Concomitantly, 8-CPT-2-O-Me-cAMP-mediated upregulation of Akt(Thr-308) protein kinase activity and p-Akt(Thr-308) levels was prevented in plasma membranes and nuclei of the cells. In contrast, silencing Epac1 gene expression reduced Akt(Ser-473) kinase activity and p-Akt(Ser-473) levels in plasma membranes, but showed negligible effects on nuclear activity. In conclusion, we show that cAMP-induced Akt kinase activation and cellular proliferation is mediated by Epac1 which appears to function as an accessory protein for Akt activation.
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Affiliation(s)
- Uma K. Misra
- Department of Pathology, Duke University Medical Center, Durham, North Carolina 27710
| | - Steven Kaczowka
- Department of Pathology, Duke University Medical Center, Durham, North Carolina 27710
| | - Salvatore V. Pizzo
- Department of Pathology, Duke University Medical Center, Durham, North Carolina 27710
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Luo G, Gruhler A, Liu Y, Jensen ON, Dickson RC. The sphingolipid long-chain base-Pkh1/2-Ypk1/2 signaling pathway regulates eisosome assembly and turnover. J Biol Chem 2008; 283:10433-44. [PMID: 18296441 PMCID: PMC2447625 DOI: 10.1074/jbc.m709972200] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2007] [Revised: 02/12/2008] [Indexed: 11/06/2022] Open
Abstract
Eisosomes are recently described fungal structures that play roles in the organization of the plasma membrane and endocytosis. Their major protein components are Pil1 and Lsp1, and previous studies showed that these proteins are phosphorylated by the sphingolipid long-chain base-activated Pkh1 and Pkh2 protein kinases in vitro. We show that Pkh1 and Pkh2 phosphorylate Pil1 and Lsp1 in vivo to produce species B, and that heat stress, which activates Pkh1 and Pkh2, generates a more highly phosphorylated species, C. Cells with low Pkh activity lack species B and C and contain abnormally organized eisosomes. To verify that Pil1 phosphorylation is essential for correct eisosome organization, phosphorylated serine and threonine residues were identified and changed to alanines. A variant Pil1 protein lacking five phosphorylation sites did not form eisosomes during log phase growth, indicating that phosphorylation is critical for eisosome organization. We also found that eisosomes are dynamic structures and disassemble when the Ypk protein kinases, which are activated by the sphingolipid-Pkh signaling pathway, are inactivated or when the sphingolipid signal is pharmacologically blocked with myriocin. We conclude that eisosome formation and turnover are regulated by the sphingolipid-Pkh1/2-Ypk1/2 signaling pathway. These data and previous data showing that endocytosis is regulated by the sphingolipid-Pkh1/2-Ypk1/2 signaling pathway suggest that Pkh1 and -2 respond to changes in membrane sphingolipids and transmit this information to eisosomes via Pil1 phosphorylation. Eisosomes then control endocytosis to align the composition and function of the plasma membrane to match demand.
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Affiliation(s)
- Guangzuo Luo
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, Kentucky 40536, USA
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Sevillano J, de Castro J, Bocos C, Herrera E, Ramos MP. Role of insulin receptor substrate-1 serine 307 phosphorylation and adiponectin in adipose tissue insulin resistance in late pregnancy. Endocrinology 2007; 148:5933-42. [PMID: 17823255 DOI: 10.1210/en.2007-0352] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Insulin resistance is a hallmark of late pregnancy both in human and rat. Adipose tissue is one of the tissues that most actively contributes to this reduced insulin sensitivity. The aim of the present study was to characterize the molecular mechanisms of insulin resistance in adipose tissue at late pregnancy. To this end, we analyzed the insulin signaling cascade in lumbar adipose tissue of nonpregnant and pregnant (d 20) rats both under basal and insulin-stimulated conditions. We found that the levels of relevant signaling proteins, such as insulin receptor (IR), IR substrate-1 (IRS-1), phosphatidylinositol 3-kinase, 3-phosphoinositide-dependent kinase-1, ERK1/2, and phosphatase and tensin homolog (PTEN) did not change at late pregnancy. However, insulin-stimulated tyrosine phosphorylation of both IR and IRS-1 were significantly decreased, coincident with decreased IRS-1/p85 association and impaired phosphorylation of AKR mouse thymoma viral protooncogene (Akt) and ERK1/2. This impaired activation of IRS-1 occurred together with an increase of IRS-1 phosphorylation at serine 307 and a decrease in adiponectin levels. To corroborate the role of IRS-1 in adipose tissue insulin resistance during pregnancy, we treated pregnant rats with the antidiabetic drug englitazone. Englitazone improved glucose tolerance, and this pharmacological reversal of insulin resistance was paralleled by an increase of adiponectin levels in adipose tissue as well as by a reduction of IRS-1 serine phosphorylation. Furthermore, the impaired insulin-stimulated tyrosine phosphorylation of IRS-1 in adipose tissue of pregnant animals could be restored ex vivo by treating isolated adipocytes with adiponectin. Together, our findings support a role for adiponectin and serine phosphorylation of IRS-1 in the modulation of insulin resistance in adipose tissue at late pregnancy.
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Affiliation(s)
- Julio Sevillano
- Facultad de Farmacia, Universidad CEU-San Pablo, Crta. Boadilla Km 5, 3, Madrid, Spain
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Luther K, Rohde M, Sturm K, Kotz A, Heesemann J, Ebel F. Characterisation of the phagocytic uptake of Aspergillus fumigatus conidia by macrophages. Microbes Infect 2007; 10:175-84. [PMID: 18248765 DOI: 10.1016/j.micinf.2007.11.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2007] [Revised: 11/06/2007] [Accepted: 11/08/2007] [Indexed: 11/17/2022]
Abstract
Aspergillus fumigatus is an opportunistic fungal pathogen responsible for severe, life-threatening infections in immunocompromised patients. Airborne conidia are the infectious agent and can reach the lower parts of the respiratory system. In the lung, phagocytes represent the first line of defence. Resident macrophages are able to track down, engulf and kill the invading spores. Phagocytosis of the conidia is therefore a prerequisite for their efficient elimination. Using human and murine macrophages we analysed the phagocytic uptake of A. fumigatus conidia. We found that conidial phagocytosis is an actin-depending process that additionally requires myosin motor, phosphoinositide-3-phosphate kinase and tyrosine kinase activity. Both broad range tyrosine kinase inhibitors and inhibitors that specifically block src kinases had a strong impact on the conidial uptake. Immunofluorescence data demonstrate the recruitment of tyrosine-phosphorylated proteins to the vicinity of engulfed conidia. Uptake of the conidia was accompanied by a strong and local reorganisation of the actin cytoskeleton, whereas no prominent reorganisation was apparent for the microtubules. Both confocal immunofluorescence and electron microscopic data revealed the presence of large ruffle-like structures engaged in the uptake of conidia. This suggests that the internalisation of A. fumigatus spores can be mediated by a process resembling macropinocytosis, which is furthermore supported by the detection of intracellular conidia within spacious vacuoles. Taken together, our data provide new insights into the internalisation of A. fumigatus spores by macrophages, a key process in the early immune defence against an Aspergillus infection.
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Affiliation(s)
- Kathrin Luther
- Max-von-Pettenkofer-Institute, Ludwig-Maximilians-University, Munich, Germany
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Stavridis MP, Lunn JS, Collins BJ, Storey KG. A discrete period of FGF-induced Erk1/2 signalling is required for vertebrate neural specification. Development 2007; 134:2889-94. [PMID: 17660197 DOI: 10.1242/dev.02858] [Citation(s) in RCA: 234] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Neural tissue formation is induced by growth factors that activate networks of signal transduction cascades that ultimately lead to the expression of early neural genes, including transcription factors of the SoxB family. Here, we report that fibroblast growth factor (FGF)-induced Erk1/2 (Mapk3 and Mapk1, respectively) mitogen-activated protein kinase (MAPK), but not phosphatidylinositol 3'-OH kinase (PI3K, Pik3r1), signalling is required for neural specification in mouse embryonic stem (ES) cells and in the chick embryo. Further, blocking Erk1/2 inhibits the onset of key SoxB genes in both mouse ES cells (Sox1) and chick embryos (Sox2 and Sox3) and, in both contexts, Erk1/2 signalling is required during only a narrow time window, as neural specification takes place. In the absence of Erk1/2 signalling, differentiation of ES cells stalls following Fgf5 upregulation. Using differentiating ES cells as a model for neural specification, we demonstrate that sustained Erk1/2 activation controls the transition from an Fgf5-positive, primitive ectoderm-like cell state to a neural progenitor cell state without attenuating bone morphogenetic protein (BMP) signalling and we also define the minimum period of Erk1/2 activity required to mediate this key developmental step. Together, these findings identify a conserved, specific and stage-dependent requirement for Erk1/2 signalling downstream of FGF-induced neural specification in higher vertebrates and provide insight into the signalling dynamics governing this process.
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Affiliation(s)
- Marios P Stavridis
- Division of Cell and Developmental Biology, University of Dundee, Dow Street, Dundee DD1 5EH, UK
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47
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Marin-Kuan M, Nestler S, Verguet C, Bezençon C, Piguet D, Delatour T, Mantle P, Cavin C, Schilter B. MAPK-ERK activation in kidney of male rats chronically fed ochratoxin A at a dose causing a significant incidence of renal carcinoma. Toxicol Appl Pharmacol 2007; 224:174-81. [PMID: 17651772 DOI: 10.1016/j.taap.2007.06.014] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2006] [Revised: 05/16/2007] [Accepted: 06/26/2007] [Indexed: 11/26/2022]
Abstract
Kidney samples of male Fischer 344 (F-344) rats fed a carcinogenic dose of OTA over 7 days, 21 days and 12 months were analysed for various cell signalling proteins known to be potentially involved in chemical carcinogenicity. OTA was found to increase the phosphorylation of atypical-PKC. This was correlated with a selective downstream activation of the MAP-kinase extracellular regulated kinases isoforms 1 and 2 (ERK1/2) and of their substrates ELK1/2 and p90RSK. Moreover, analysis of effectors acting upstream of PKC indicated a possible mobilisation of the insulin-like growth factor-1 receptor (lGFr) and phosphoinositide-dependent kinase-1 (PDK1) system. An increased histone deacetylase (HDAC) enzymatic activity associated with enhanced HDAC3 protein expression was also observed. These findings are potentially relevant with respect to the understanding of OTA nephrocarcinogenicity. HDAC-induced gene silencing has previously been shown to play a role in tumour development. Furthermore, PKC and the MEK-ERK MAP-kinase pathways are known to play important roles in cell proliferation, cell survival, anti-apoptotic activity and renal cancer development.
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Affiliation(s)
- M Marin-Kuan
- Nestlé Research Center, PO Box 44, Vers-chez-les-Blanc, CH-1000 Lausanne 26, Switzerland.
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Föller M, Mahmud H, Koka S, Lang F. Reduced Ca2+ entry and suicidal death of erythrocytes in PDK1 hypomorphic mice. Pflugers Arch 2007; 455:939-49. [PMID: 17899170 DOI: 10.1007/s00424-007-0336-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2007] [Revised: 08/07/2007] [Accepted: 08/23/2007] [Indexed: 12/16/2022]
Abstract
The phosphoinositide-dependent kinase PDK1 is a key element in the phosphoinositol-3-kinase signalling pathway, which is involved in the regulation of ion channels, transporters, cell volume and cell survival. Eryptosis, the suicidal death of erythrocytes, is characterized by decrease in cell volume, cell membrane blebbing and phospholipids scrambling with phosphatidylserine exposure at the cell surface. Oxidative stress, osmotic shock or Cl- removal trigger eryptosis by activation of Ca2+-permeable cation channels and subsequent increase in cytosolic Ca2+ activity. To explore the impact of PDK1 for erythrocyte survival, eryptosis was analysed in hypomorphic mice (pdk1hm) expressing only some 25% of PDK1 and in their wild-type littermates (pdk1wt). Cell volume was estimated from forward scatter and phosphatidylserine exposure from annexin-V binding in fluorescence activated cell sorter analysis. Forward scatter was smaller in pdk1hm than in pdk1wt erythrocytes. Oxidative stress (100 microM tert-butylhydroperoxide), osmotic shock (+300 mM sucrose) and Cl- removal (replacement of Cl- with gluconate) all decreased forward scatter and increased the percentage of annexin-V-binding erythrocytes from both pdk1hm and pdk1wt mice. After treatment, the forward scatter was similar in both genotypes, but the percentage of annexin-V binding was significantly smaller in pdk1hm than in pdk1wt erythrocytes. According to Fluo-3 fluorescence, cytosolic Ca2+ activity was significantly smaller in pdk1hm than in pdk1wt erythrocytes. Treatment with Ca2+-ionophore ionomycin (1 microM) was followed by an increase in annexin-V binding to similar levels in pdk1hm and pdk1wt erythrocytes. The experiments reveal that PDK1 deficiency is associated with decreased Ca2+ entry into erythrocytes and thus with blunted eryptotic effects of oxidative stress, osmotic shock and Cl- removal.
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Affiliation(s)
- Michael Föller
- Department of Physiology, University of Tuebingen, Gmelinstr. 5, 72076 Tübingen, Germany
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Harper L, Kashiwagi Y, Pusey CD, Hendry BM, Domin J. Platelet-derived growth factor reorganizes the actin cytoskeleton through 3-phosphoinositide-dependent and 3-phosphoinositide-independent mechanisms in human mesangial cells. Nephron Clin Pract 2007; 107:p45-56. [PMID: 17804914 DOI: 10.1159/000107805] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2006] [Accepted: 05/08/2007] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Platelet-derived growth factor (PDGF) is a potent activator of mesangial cell proliferation and migration. Although phosphoinositide 3-kinase (PI3K) enzymes are important downstream targets of the PDGF receptor, the contribution made by their 3-phosphoinositide products in the reorganization of actin cytoskeleton and focal adhesions has been questioned. METHODS AND RESULTS Pharmacological inhibition of the PI3K activity blocks PDGF-induced migration of human primary mesangial cells using an in vitro scrape wound healing assay. Acute (<10 min) inhibition of the PI3K activity did not alter the effect of PDGF on either stress fibre dissolution or reorganization of focal adhesions. However, at later times (>30 min), PDGF-stimulated responses were inhibited. In contrast, PDGF-stimulated membrane ruffling remained insensitive to PI3K inhibitors throughout. Inhibition of protein kinase C and Erk also attenuated PDGF-stimulated mesangial cell migration; however, neither signaling pathway was responsible for the initial effects on filamentous actin and focal adhesions. CONCLUSIONS We propose that following PDGF stimulation of mesangial cells, reorganization of the actin cytoskeleton occurs in a biphasic manner. The mechanism responsible for mesangial cell migration that occurs immediately following PDGF stimulation may serve to 'prime' for the subsequent 3-phosphoinositide-, protein-kinase-C-, and Erk-dependent migration.
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Sargeant AM, Klein RD, Rengel RC, Clinton SK, Kulp SK, Kashida Y, Yamaguchi M, Wang X, Chen CS. Chemopreventive and bioenergetic signaling effects of PDK1/Akt pathway inhibition in a transgenic mouse model of prostate cancer. Toxicol Pathol 2007; 35:549-61. [PMID: 17562488 DOI: 10.1080/01926230701338966] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The phosphoinositide-dependent kinase 1 (PDK1)/Akt pathway is an important regulator of multiple biological processes including cell growth, survival, and glucose metabolism. In light of the mechanistic link between Akt signaling and prostate tumorigenesis, we evaluated the chemopreventive relevance of inhibiting this pathway in the transgenic adenocarcinoma of the model prostate (TRAMP) mouse with OSU03012, a celecoxib-derived, but COX-2-inactive, PDK1 inhibitor. Beginning at ten weeks of age when prostatic intraepithelial neoplasia (PIN) lesions are well developed, TRAMP mice received OSU03012 via daily oral gavage for 8 weeks. The drug treatment significantly decreased the weight of all 4 prostate lobes as well as the grade of epithelial proliferation in the dorsal and lateral lobes compared to vehicle-treated control mice. The incidences of carcinoma and metastasis were decreased, although not to statistically significant levels. Treated mice lost body fat and failed to gain weight independent of food intake. This change and periportal hepatocellular atrophy can be linked to sustained PDK1 inhibition through downstream inactivation of glycogen synthase. Centrilobular hepatocellular hypertrophy and necrosis of Type II skeletal myofibers were also compound-related effects. We conclude that targeting of the PDK1/Akt pathway has chemopreventive relevance in prostate cancer and causes other in vivo effects mediated in part by an alteration of bioenergetic signaling.
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Affiliation(s)
- Aaron M Sargeant
- Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, The Ohio State University, Columbus, OH 43210-1291, USA
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