1
|
Qin K, Yu M, Fan J, Wang H, Zhao P, Zhao G, Zeng W, Chen C, Wang Y, Wang A, Schwartz Z, Hong J, Song L, Wagstaff W, Haydon RC, Luu HH, Ho SH, Strelzow J, Reid RR, He TC, Shi LL. Canonical and noncanonical Wnt signaling: Multilayered mediators, signaling mechanisms and major signaling crosstalk. Genes Dis 2024; 11:103-134. [PMID: 37588235 PMCID: PMC10425814 DOI: 10.1016/j.gendis.2023.01.030] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 11/01/2022] [Accepted: 01/29/2023] [Indexed: 08/18/2023] Open
Abstract
Wnt signaling plays a major role in regulating cell proliferation and differentiation. The Wnt ligands are a family of 19 secreted glycoproteins that mediate their signaling effects via binding to Frizzled receptors and LRP5/6 coreceptors and transducing the signal either through β-catenin in the canonical pathway or through a series of other proteins in the noncanonical pathway. Many of the individual components of both canonical and noncanonical Wnt signaling have additional functions throughout the body, establishing the complex interplay between Wnt signaling and other signaling pathways. This crosstalk between Wnt signaling and other pathways gives Wnt signaling a vital role in many cellular and organ processes. Dysregulation of this system has been implicated in many diseases affecting a wide array of organ systems, including cancer and embryological defects, and can even cause embryonic lethality. The complexity of this system and its interacting proteins have made Wnt signaling a target for many therapeutic treatments. However, both stimulatory and inhibitory treatments come with potential risks that need to be addressed. This review synthesized much of the current knowledge on the Wnt signaling pathway, beginning with the history of Wnt signaling. It thoroughly described the different variants of Wnt signaling, including canonical, noncanonical Wnt/PCP, and the noncanonical Wnt/Ca2+ pathway. Further description involved each of its components and their involvement in other cellular processes. Finally, this review explained the various other pathways and processes that crosstalk with Wnt signaling.
Collapse
Affiliation(s)
- Kevin Qin
- Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
| | - Michael Yu
- Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
| | - Jiaming Fan
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
- Ministry of Education Key Laboratory of Diagnostic Medicine, and Department of Clinical Biochemistry, The School of Laboratory Medicine, Chongqing Medical University, Chongqing 400016, China
| | - Hongwei Wang
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
| | - Piao Zhao
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
- Departments of Orthopaedic Surgery and Urology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China
| | - Guozhi Zhao
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
- Departments of Orthopaedic Surgery and Urology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China
| | - Wei Zeng
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
- Department of Interventional Neurology, The First Dongguan Affiliated Hospital, Guangdong Medical University, Dongguan, Guangdong 523475, China
| | - Connie Chen
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
| | - Yonghui Wang
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
- Department of Clinical Laboratory Medicine, Shanghai Jiaotong University School of Medicine, Shanghai 200000, China
| | - Annie Wang
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
- Laboratory of Craniofacial Biology and Development, Department of Surgery Section of Plastic Surgery, The University of Chicago Medical Center, Chicago, IL 60637, USA
| | - Zander Schwartz
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
- School of Biomedical Engineering, Vanderbilt University, Nashville, TN 37235, USA
| | - Jeffrey Hong
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
| | - Lily Song
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
| | - William Wagstaff
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
| | - Rex C. Haydon
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
| | - Hue H. Luu
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
| | - Sherwin H. Ho
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
| | - Jason Strelzow
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
| | - Russell R. Reid
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
- Laboratory of Craniofacial Biology and Development, Department of Surgery Section of Plastic Surgery, The University of Chicago Medical Center, Chicago, IL 60637, USA
| | - Tong-Chuan He
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
- Laboratory of Craniofacial Biology and Development, Department of Surgery Section of Plastic Surgery, The University of Chicago Medical Center, Chicago, IL 60637, USA
| | - Lewis L. Shi
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
| |
Collapse
|
2
|
Godfroy O, Zheng M, Yao H, Henschen A, Peters AF, Scornet D, Colin S, Ronchi P, Hipp K, Nagasato C, Motomura T, Cock JM, Coelho SM. The baseless mutant links protein phosphatase 2A with basal cell identity in the brown alga Ectocarpus. Development 2023; 150:dev201283. [PMID: 36786333 PMCID: PMC10112911 DOI: 10.1242/dev.201283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 01/16/2023] [Indexed: 02/15/2023]
Abstract
The first mitotic division of the initial cell is a key event in all multicellular organisms and is associated with the establishment of major developmental axes and cell fates. The brown alga Ectocarpus has a haploid-diploid life cycle that involves the development of two multicellular generations: the sporophyte and the gametophyte. Each generation deploys a distinct developmental programme autonomously from an initial cell, the first cell division of which sets up the future body pattern. Here, we show that mutations in the BASELESS (BAS) gene result in multiple cellular defects during the first cell division and subsequent failure to produce basal structures during both generations. BAS encodes a type B″ regulatory subunit of protein phosphatase 2A (PP2A), and transcriptomic analysis identified potential effector genes that may be involved in determining basal cell fate. The bas mutant phenotype is very similar to that observed in distag (dis) mutants, which lack a functional Tubulin-binding co-factor Cd1 (TBCCd1) protein, indicating that TBCCd1 and PP2A are two essential components of the cellular machinery that regulates the first cell division and mediates basal cell fate determination.
Collapse
Affiliation(s)
- Olivier Godfroy
- Laboratory of Integrative Biology of Marine Models, Sorbonne Université, UPMC University of Paris 06, CNRS, UMR 8227, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff, France
| | - Min Zheng
- Department of Algal Development and Evolution, Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
| | - Haiqin Yao
- Laboratory of Integrative Biology of Marine Models, Sorbonne Université, UPMC University of Paris 06, CNRS, UMR 8227, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff, France
| | - Agnes Henschen
- Department of Algal Development and Evolution, Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
| | | | - Delphine Scornet
- Laboratory of Integrative Biology of Marine Models, Sorbonne Université, UPMC University of Paris 06, CNRS, UMR 8227, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff, France
| | - Sebastien Colin
- Department of Algal Development and Evolution, Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
| | - Paolo Ronchi
- Electron Microscopy Core Facility, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Katharina Hipp
- Department of Algal Development and Evolution, Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
| | - Chikako Nagasato
- Muroran Marine Station, Field Science Center for Northern Biosphere, Hokkaido University, Muroran, 051-0013, Japan
| | - Taizo Motomura
- Muroran Marine Station, Field Science Center for Northern Biosphere, Hokkaido University, Muroran, 051-0013, Japan
| | - J. Mark Cock
- Laboratory of Integrative Biology of Marine Models, Sorbonne Université, UPMC University of Paris 06, CNRS, UMR 8227, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff, France
| | - Susana M. Coelho
- Department of Algal Development and Evolution, Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
| |
Collapse
|
3
|
Deng X, He X, Yang Z, Huang J, Zhao L, Wen M, Hu X, Zou Z. Clustering analysis and prognostic model based on PI3K/AKT-related genes in pancreatic cancer. Front Oncol 2023; 13:1112104. [PMID: 37124502 PMCID: PMC10140326 DOI: 10.3389/fonc.2023.1112104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 03/29/2023] [Indexed: 05/02/2023] Open
Abstract
Background Pancreatic cancer is one of most aggressive malignancies with a dismal prognosis. Activation of PI3K/AKT signaling is instrumental in pancreatic cancer tumorigenesis. The aims of this study were to identify the molecular clustering, prognostic value, relationship with tumor immunity and targeting of PI3K/AKT-related genes (PARGs) in pancreatic cancer using bioinformatics. Methods The GSEA website was searched for PARGs, and pancreatic cancer-related mRNA data and clinical profiles were obtained through TCGA downloads. Prognosis-related genes were identified by univariate Cox regression analysis, and samples were further clustered by unsupervised methods to identify significant differences in survival, clinical information and immune infiltration between categories. Next, a prognostic model was constructed using Lasso regression analysis. The model was well validated by univariate and multivariate Cox regression analyses, Kaplan-Meier survival analysis and ROC curves, and correlations between risk scores and patient pathological characteristics were identified. Finally, GSEA, drug prediction and immune checkpoint protein analyses were performed. Results Pancreatic cancers were divided into Cluster 1 (C1) and Cluster 2 (C1) according to PARG mRNA expression. C1 exhibited longer overall survival (OS) and higher immune scores and CTLA4 expression, whereas C2 exhibited more abundant PD-L1. A 6-PARG-based prognostic model was constructed to divide pancreatic cancer patients into a high-risk score (HRS) group and a low-risk score (LRS) group, where the HRS group exhibited worse OS. The risk score was defined as an independent predictor of OS. The HRS group was significantly associated with pancreatic cancer metastasis, aggregation and immune score. Furthermore, the HRS group exhibited immunosuppression and was sensitive to radiotherapy and guitarbine chemotherapy. Multidrug sensitivity prediction analysis indicated that the HRS group may be sensitive to PI3K/AKT signaling inhibitors (PIK-93, GSK2126458, CAL-101 and rapamycin) and ATP concentration regulators (Thapsigargin). In addition, we confirmed the oncogenic effect of protein phosphatase 2 regulatory subunit B'' subunit alpha (PPP2R3A) in pancreatic cancer in vitro and in vivo. Conclusions PARGs predict prognosis, tumor immune profile, radiotherapy and chemotherapy drug sensitivity and are potential predictive markers for pancreatic cancer treatment that can help clinicians make decisions and personalize treatment.
Collapse
Affiliation(s)
- Xiangying Deng
- Yiyang Key Laboratory of Chemical Small Molecule Anti-Tumor Targeted Therapy, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Yiyang Medical College, Yiyang, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
| | - Xu He
- Yiyang Key Laboratory of Chemical Small Molecule Anti-Tumor Targeted Therapy, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Yiyang Medical College, Yiyang, China
- Department of Science and Education, Yiyang Central Hospital, Yiyang, China
- The Hunan Provincial Key Laboratory of Precision Diagnosis and Treatment for Gastrointestinal Tumor, Xiangya Hospital, Central South University, Changsha, China
| | - Zehua Yang
- Yiyang Key Laboratory of Chemical Small Molecule Anti-Tumor Targeted Therapy, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Yiyang Medical College, Yiyang, China
| | - Jing Huang
- Yiyang Key Laboratory of Chemical Small Molecule Anti-Tumor Targeted Therapy, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Yiyang Medical College, Yiyang, China
| | - Lin Zhao
- Department of Pathology, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Min Wen
- Yiyang Key Laboratory of Chemical Small Molecule Anti-Tumor Targeted Therapy, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Yiyang Medical College, Yiyang, China
- Department of Biochemistry and Molecular Biology, Hunan Province Key Laboratory of Basic and Applied Hematology, Hunan Key Laboratory of Animal Models for Human Diseases, School of Life Sciences, Xiangya School of Medicine, Central South University, Changsha, China
| | - Xiyuan Hu
- Department of Biochemistry and Molecular Biology, Hunan Province Key Laboratory of Basic and Applied Hematology, Hunan Key Laboratory of Animal Models for Human Diseases, School of Life Sciences, Xiangya School of Medicine, Central South University, Changsha, China
| | - Zizheng Zou
- Yiyang Key Laboratory of Chemical Small Molecule Anti-Tumor Targeted Therapy, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Yiyang Medical College, Yiyang, China
- Department of Science and Education, Yiyang Central Hospital, Yiyang, China
- The Hunan Provincial Key Laboratory of Precision Diagnosis and Treatment for Gastrointestinal Tumor, Xiangya Hospital, Central South University, Changsha, China
- *Correspondence: Zizheng Zou,
| |
Collapse
|
4
|
He JJ, Shang L, Yu QW, Jiao N, Qiu S, Zhu WX, Wu DF, Tian YE, Zhang Q. High expression of protein phosphatase 2 regulatory subunit B'' alpha predicts poor outcome in hepatocellular carcinoma patients after liver transplantation. World J Gastrointest Oncol 2021; 13:716-731. [PMID: 34322200 PMCID: PMC8299934 DOI: 10.4251/wjgo.v13.i7.716] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Revised: 06/06/2021] [Accepted: 06/23/2021] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Protein phosphatase 2 regulatory subunit B'' alpha (PPP2R3A) gene has been reported in other tumors, but the influence of PPP2R3A gene expression on the occurrence, development, and prognosis of hepatocellular carcinoma (HCC) remains unclear.
AIM To investigate whether the PPP2R3A gene could be used to predict tumor recurrence and survival of HCC patients after liver transplantation (LT).
METHODS Diseased liver tissues of HCC patients after LT were collected as well as their clinical data and follow-up information. The immunohistochemical method was used to detect the expression of PPP2R3A protein in the tissues of 108 patients with primary liver cancer. The χ2 test was used to analyze the relationship between PPP2R3A protein expression levels and the clinicopathological features of tumors. The Kaplan-Meier method was used to analyze overall postoperative survival. The COX proportional hazard model was used to analyze adverse prognostic factors.
RESULTS Immunohistochemistry showed that the PPP2R3A protein was mainly expressed in the cytoplasm of HCC cells. Compared to corresponding peritumoral tissues, expression was higher in HCC tissues (P ≤ 0.001). Correlation analysis showed that high PPP2R3A expression was correlated with preoperative serum alpha-fetoprotein (AFP) levels (P = 0.003), tumor-node-metastasis-t stage (P ≤ 0.001), and envelope invasion (P = 0.001). Univariate analysis showed that overall survival (P ≤ 0.001) and recurrence-free survival (P = 0.025) of patients with high PPP2R3A expression (≥ 4 points) were poor compared to those with low expression (< 4 points). The overall survival rates or recurrence-free survival rates at 1, 2, and 3 years with high PPP2R3A expression were 73%, 38%, and 23% or 31%, 23%, and 23%, respectively. Multivariate analysis showed that high PPP2R3A expression (hazard ratio = 2.900, 95% confidence interval: 1.411–5.960, P = 0.004) was an independent survival risk factor of HCC patients after LT, and it was also an independent predictor of postoperative tumor recurrence. This study also showed in patients with AFP ≥ 400 ng/mL, the overall survival (P ≤ 0.001) and recurrence-free survival (P = 0.023) of those with high PPP2R3A expression were significantly worse compared to those with low PPP2R3A expression. When PPP2R3A expression was low, the overall survival rate (P = 0.461) or recurrence-free survival rate (P = 0.072) after LT in patients with AFP < 400 ng/mL and ≥ 400 ng/mL was not significantly difference. The 1, 2, and 3 year survival rate of patients with low PPP2R3A expression and AFP < 400 ng/mL were 98%, 80%, and 69%, respectively, while patients who met Hangzhou criteria had a post-transplant 1, 2, and 3 years overall survival rate of 89%, 66%, and 55%, respectively.
CONCLUSION High expression of PPP2R3A might be a potential marker for predicting poor prognosis of HCC after LT. Combined with serum AFP levels, PPP2R3A might enhance the accuracy of predicting HCC outcome in patients after LT and supplement the efficacy of the Hangzhou criteria.
Collapse
Affiliation(s)
- Jia-Jia He
- Clinical College of General Hospital of Chinese People's Armed Police Force, Anhui Medical University, Hefei 230032, Anhui, China
- Department of Organ Transplantation, The Third Medical Center of Chinese PLA General Hospital, Beijing 100039, China
| | - Lei Shang
- Department of Health Statistics, Fourth Military Medical University, Xi'an 710032, Shanxi Province, China
| | - Qun-Wei Yu
- Department of Ophthalmology, The Third Medical Center of Chinese PLA General Hospital, Beijing 100039, China
| | - Ning Jiao
- Department of Organ Transplantation, The Third Medical Center of Chinese PLA General Hospital, Beijing 100039, China
| | - Shuang Qiu
- Department of Organ Transplantation, The Third Medical Center of Chinese PLA General Hospital, Beijing 100039, China
| | - Wei-Xiong Zhu
- Department of Organ Transplantation, The Third Medical Center of Chinese PLA General Hospital, Beijing 100039, China
| | - Dong-Feng Wu
- Department of Organ Transplantation, The Third Medical Center of Chinese PLA General Hospital, Beijing 100039, China
| | - Yun-Er Tian
- Department of Organ Transplantation, The Third Medical Center of Chinese PLA General Hospital, Beijing 100039, China
| | - Qing Zhang
- Clinical College of General Hospital of Chinese People's Armed Police Force, Anhui Medical University, Hefei 230032, Anhui, China
- Department of Organ Transplantation, The Third Medical Center of Chinese PLA General Hospital, Beijing 100039, China
| |
Collapse
|
5
|
He JJ, Shang L, Yu QW, Jiao N, Qiu S, Zhu WX, Wu DF, Tian YE, Zhang Q. High expression of protein phosphatase 2 regulatory subunit B'' alpha predicts poor outcome in hepatocellular carcinoma patients after liver transplantation. World J Gastrointest Oncol 2021. [DOI: 10.4251/wjgo.v13.i7.541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
|
6
|
Bryant JP, Levy A, Heiss J, Banasavadi-Siddegowda YK. Review of PP2A Tumor Biology and Antitumor Effects of PP2A Inhibitor LB100 in the Nervous System. Cancers (Basel) 2021; 13:cancers13123087. [PMID: 34205611 PMCID: PMC8235527 DOI: 10.3390/cancers13123087] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 06/17/2021] [Accepted: 06/18/2021] [Indexed: 12/14/2022] Open
Abstract
Simple Summary Central and peripheral nervous system tumors represent a heterogenous group of neoplasms which often demonstrate resistance to treatment. Given that these tumors are often refractory to conventional therapy, novel pharmaceutical regimens are needed for successfully treating this pathology. One such therapeutic is the serine/threonine phosphatase inhibitor, LB100. LB100 is a water-soluble competitive protein phosphtase inhibitor that has demonstrated antitumor effects in preclinical and clinical trials. In this review, we aim to summarize current evidence demonstrating the efficacy of LB100 as an inhibitor of nervous system tumors. Furthermore, we review the involvement of the well-studied phosphatase, protein phosphatase 2A, in oncogenic cell signaling pathways, neurophysiology, and neurodevelopment. Abstract Protein phosphatase 2A (PP2A) is a ubiquitous serine/threonine phosphatase implicated in a wide variety of regulatory cellular functions. PP2A is abundant in the mammalian nervous system, and dysregulation of its cellular functions is associated with myriad neurodegenerative disorders. Additionally, PP2A has oncologic implications, recently garnering attention and emerging as a therapeutic target because of the antitumor effects of a potent PP2A inhibitor, LB100. LB100 abrogation of PP2A is believed to exert its inhibitory effects on tumor progression through cellular chemo- and radiosensitization to adjuvant agents. An updated and unifying review of PP2A biology and inhibition with LB100 as a therapeutic strategy for targeting cancers of the nervous system is needed, as other reviews have mainly covered broader applications of LB100. In this review, we discuss the role of PP2A in normal cells and tumor cells of the nervous system. Furthermore, we summarize current evidence regarding the therapeutic potential of LB100 for treating solid tumors of the nervous system.
Collapse
Affiliation(s)
- Jean-Paul Bryant
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA; (J.-P.B.); (J.H.)
| | - Adam Levy
- Miller School of Medicine, University of Miami, Miami, FL 33136, USA;
| | - John Heiss
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA; (J.-P.B.); (J.H.)
| | - Yeshavanth Kumar Banasavadi-Siddegowda
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA; (J.-P.B.); (J.H.)
- Correspondence: ; Tel.: +1-301-451-0970
| |
Collapse
|
7
|
Dzulko M, Pons M, Henke A, Schneider G, Krämer OH. The PP2A subunit PR130 is a key regulator of cell development and oncogenic transformation. Biochim Biophys Acta Rev Cancer 2020; 1874:188453. [PMID: 33068647 DOI: 10.1016/j.bbcan.2020.188453] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 10/10/2020] [Accepted: 10/11/2020] [Indexed: 12/25/2022]
Abstract
Protein phosphatase 2A (PP2A) is a major serine/threonine phosphatase. This enzyme is involved in a plethora of cellular processes, including apoptosis, autophagy, cell proliferation, and DNA repair. Remarkably, PP2A can act as a context-dependent tumor suppressor or promoter. Active PP2A complexes consist of structural (PP2A-A), regulatory (PP2A-B), and catalytic (PP2A-C) subunits. The regulatory subunits define the substrate specificity and the subcellular localization of the holoenzyme. Here we condense the increasing evidence that the PP2A B-type subunit PR130 is a critical regulator of cell identity and oncogenic transformation. We summarize knowledge on the biological functions of PR130 in normal and transformed cells, targets of the PP2A-PR130 complex, and how diverse extra- and intracellular stimuli control the expression and activity of PR130. We additionally review the impact of PP2A-PR130 on cardiac functions, neuronal processes, and anti-viral defense and how this might affect cancer development and therapy.
Collapse
Affiliation(s)
- Melanie Dzulko
- Department of Toxicology, University Medical Center, 55131 Mainz, Germany
| | - Miriam Pons
- Department of Toxicology, University Medical Center, 55131 Mainz, Germany
| | - Andreas Henke
- Section of Experimental Virology, Institute of Medical Microbiology, Jena University Hospital, Friedrich Schiller University, 07745 Jena, Germany
| | - Günter Schneider
- Klinik und Poliklinik für Innere Medizin II, Technical University of Munich, 81675 Munich, Germany
| | - Oliver H Krämer
- Department of Toxicology, University Medical Center, 55131 Mainz, Germany.
| |
Collapse
|
8
|
Li J, Su X, Dai L, Chen N, Fang C, Dong Z, Fu J, Yu Y, Wang W, Zhang H, Wang H, Ji Y, Liu Y, Cheng L, Shi G, Zhang S, Yang Y, Deng H. Temporal DNA methylation pattern and targeted therapy in colitis-associated cancer. Carcinogenesis 2020; 41:235-244. [PMID: 31802101 DOI: 10.1093/carcin/bgz199] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 11/19/2019] [Accepted: 12/04/2019] [Indexed: 02/05/2023] Open
Abstract
DNA methylation plays a crucial role in the pathogenesis of various diseases, including colorectal cancer (CRC). However, the global and temporal DNA methylation pattern during initiation and progression of colitis-associated cancer (CAC) are still unknown, including the potential therapeutic strategy of targeting methylation for CAC. In the present study, the global DNA methylation pattern was determined at different time points during CAC using DNA methylation sequencing, followed by the Starburst plot integrating alterations and potential functional prediction analysis. After demonstrating the regulatory role of DNA methyltransferases (DNMTs) on the expression of hub-genes in CRC cells, DNMT inhibitors were administered to treat CAC mice. Our results indicated that 811 genes were hypermethylated at different time points during initiation and progression of CAC. Genes that were downregulated and hypermethylated during CAC, including hub-genes BAD and inositol polyphosphate phosphatase-like 1 (INPPL1), were involved in MAPK signaling pathways, kit receptor signaling pathways, apoptosis and EGF/EGFR signaling pathways. Upregulated DNMTs (DNMT1, DNMT3A and DNMT3B) mediated downregulation and hypermethylation of BAD and INPPL1 in CAC and CRC cells. Low doses of DNMT inhibitors (decitabine (DAC) and azacitidine (AZA)) exerted efficient antitumor effects in CAC, accompanied with upregulation of BAD and INPPL1 expression, and apoptosis induction. In summary, the present study demonstrates the temporal DNA methylation pattern during CAC and provides a novel therapeutic strategy for treating this disease.
Collapse
Affiliation(s)
- Junshu Li
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan, P. R. China
| | - Xiaolan Su
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan, P. R. China
| | - Lei Dai
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan, P. R. China
| | - Na Chen
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan, P. R. China
| | - Chao Fang
- Department of Gastrointestinal Surgery, West China Hospital and State Key Laboratory of Biotherapy, Sichuan University, Chengdu, Sichuan 610041, P. R. China
| | - Zhexu Dong
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan, P. R. China
| | - Jiamei Fu
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan, P. R. China
| | - Yan Yu
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan, P. R. China
| | - Wenshuang Wang
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan, P. R. China
| | - Hantao Zhang
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan, P. R. China
| | - Huiling Wang
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan, P. R. China
| | - Yanhong Ji
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan, P. R. China
| | - Yi Liu
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan, P. R. China
| | - Lin Cheng
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan, P. R. China
| | - Gang Shi
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan, P. R. China
| | - Shuang Zhang
- Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan, P. R. China
| | - Yang Yang
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan, P. R. China
| | - Hongxin Deng
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan, P. R. China
| |
Collapse
|
9
|
Hein AL, Brandquist ND, Ouellette CY, Seshacharyulu P, Enke CA, Ouellette MM, Batra SK, Yan Y. PR55α regulatory subunit of PP2A inhibits the MOB1/LATS cascade and activates YAP in pancreatic cancer cells. Oncogenesis 2019; 8:63. [PMID: 31659153 PMCID: PMC6817822 DOI: 10.1038/s41389-019-0172-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 10/02/2019] [Accepted: 10/04/2019] [Indexed: 12/11/2022] Open
Abstract
PP2A holoenzyme complexes are responsible for the majority of Ser/Thr phosphatase activities in human cells. Each PP2A consists of a catalytic subunit (C), a scaffold subunit (A), and a regulatory subunit (B). While the A and C subunits each exists only in two highly conserved isoforms, a large number of B subunits share no homology, which determines PP2A substrate specificity and cellular localization. It is anticipated that different PP2A holoenzymes play distinct roles in cellular signaling networks, whereas PP2A has only generally been defined as a putative tumor suppressor, which is mostly based on the loss-of-function studies using pharmacological or biological inhibitors for the highly conserved A or C subunit of PP2A. Recent studies of specific pathways indicate that some PP2A complexes also possess tumor-promoting functions. We have previously reported an essential role of PR55α, a PP2A regulatory subunit, in the support of oncogenic phenotypes, including in vivo tumorigenicity/metastasis of pancreatic cancer cells. In this report, we have elucidated a novel role of PR55α-regulated PP2A in the activation of YAP oncoprotein, whose function is required for anchorage-independent growth during oncogenesis of solid tumors. Our data show two lines of YAP regulation by PR55α: (1) PR55α inhibits the MOB1-triggered autoactivation of LATS1/2 kinases, the core member of the Hippo pathway that inhibits YAP by inducing its proteasomal degradation and cytoplasmic retention and (2) PR55α directly interacts with and regulates YAP itself. Accordingly, PR55α is essential for YAP-promoted gene transcriptions, as well as for anchorage-independent growth, in which YAP plays a key role. In summary, current findings demonstrate a novel YAP activation mechanism based on the PR55α-regulated PP2A phosphatase.
Collapse
Affiliation(s)
- Ashley L Hein
- Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Nichole D Brandquist
- Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Caroline Y Ouellette
- Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, NE, USA
| | | | - Charles A Enke
- Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Michel M Ouellette
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA.,Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, USA
| | - Surinder K Batra
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA.
| | - Ying Yan
- Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, NE, USA. .,Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA.
| |
Collapse
|
10
|
Chen H, Xu J, Wang P, Shu Q, Huang L, Guo J, Zhang X, Zhang H, Wang Y, Shen Z, Chen X, Zhang Q. Protein phosphatase 2 regulatory subunit B''Alpha silencing inhibits tumor cell proliferation in liver cancer. Cancer Med 2019; 8:7741-7753. [PMID: 31647192 PMCID: PMC6912040 DOI: 10.1002/cam4.2620] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Revised: 09/29/2019] [Accepted: 10/06/2019] [Indexed: 12/24/2022] Open
Abstract
Aim To explore the effects of protein phosphatase 2 regulatory subunit B''Alpha (PPP2R3A) on the proliferation and migration of liver cancer cells. Methods Expression of PPP2R3A in tumor tissues of hepatocellular carcinoma (HCC) patients was detected by immunohistochemistry and western blotting. In two liver cancer cell lines (HepG2 and HuH7), PPP2R3A expression was silenced and then overexpression with PPP2R3A lentiviral vectors, and the effects of PPP2R3A knockdown or overexpression on the proliferation, cell cycle, migration, and invasion of HCC cells were determined in vitro. In a xenograft cancer model in nude mice, the in vivo effects of PPP2R3A knockdown on tumor growth and cancer cell proliferation were evaluated. Results PPP2R3A expression was found in tumor foci in six of eight HCC samples, at a level higher than that in the adjacent para‐tumor tissues. PPP2R3A expression was observed primarily in the cytoplasm of the cancer cells. Knockdown of PPP2R3A resulted in significant inhibition of hepatoma cell proliferation (P < .05), migration (P < .01), and invasion (P < .01) as well as a significant delay in the G1/S transition in both liver cancer lines (P < .05) and increased p53 expression. Conversely, overexpression of PPP2R3A promoted the proliferation (P < .05) and altered cell cycle progression (P < .05) of both liver cancer cell lines. In vivo, PPP2R3A knockdown in liver cancer cells led to significant reductions in the tumor volume (P < .001) and the expression of Ki‐67 in tumor tissues (P < .05). Conclusion PPP2R3A may play a role in liver cancer via the regulation of tumor cell proliferation and invasion.
Collapse
Affiliation(s)
- Huijuan Chen
- Department of Liver Transplantation, The Third Medical Centre, Chinese PLA (People's Liberation Army) General Hospital, Beijing, China.,Graduate School, Anhui Medical University, Hefei, China
| | - Jing Xu
- National Translational Science Center for Molecular Medicine & Department of Cell Biology, State Key Laboratory of Cancer Biology, Fourth Military Medical University, Xi'an, China
| | - Peixiao Wang
- Department of Gastroenterology, Henan Children's Hospital, Zhengzhou, China
| | - Qingming Shu
- Pathology Department, The Third Medical Centre, Chinese PLA (People's Liberation Army) General Hospital, Beijing, China
| | - Lihong Huang
- Medical Department, The Third Medical Centre, Chinese PLA (People's Liberation Army) General Hospital, Beijing, China
| | - Jing Guo
- Medical Department, The Third Medical Centre, Chinese PLA (People's Liberation Army) General Hospital, Beijing, China
| | - Xuyi Zhang
- Medical Department, The Third Medical Centre, Chinese PLA (People's Liberation Army) General Hospital, Beijing, China
| | - Hongying Zhang
- Medical Department, The Third Medical Centre, Chinese PLA (People's Liberation Army) General Hospital, Beijing, China
| | - Ying Wang
- Department of Liver Transplantation, The Third Medical Centre, Chinese PLA (People's Liberation Army) General Hospital, Beijing, China
| | - Zhongyang Shen
- Department of Liver Transplantation, The Third Medical Centre, Chinese PLA (People's Liberation Army) General Hospital, Beijing, China.,Department of Transplantation Surgery, Tianjin First Central Hospital, Tianjin, China
| | - Xinguo Chen
- Department of Liver Transplantation, The Third Medical Centre, Chinese PLA (People's Liberation Army) General Hospital, Beijing, China
| | - Qing Zhang
- Department of Liver Transplantation, The Third Medical Centre, Chinese PLA (People's Liberation Army) General Hospital, Beijing, China
| |
Collapse
|
11
|
Baskaran R, Velmurugan BK. Protein phosphatase 2A as therapeutic targets in various disease models. Life Sci 2018; 210:40-46. [PMID: 30170071 DOI: 10.1016/j.lfs.2018.08.063] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 07/25/2018] [Accepted: 08/27/2018] [Indexed: 12/24/2022]
Abstract
There are a large number of signalling pathways responsible for transmitting information within the cell. Although cellular signalling is thought to be majorly governed by protein kinases 'cascade effects'; their antagonists protein phosphatases also play a crucial dual role in signal transduction. By dephosphorylating the proteins involved in signalling pathways, phosphatases may lead to their activation and sometimes they may terminate a signal generated by kinases activity. Due to counterbalancing the function of phosphorylation, the protein phosphatases are very important to signal transduction processes and thus the control of phosphatase activity is as significant as kinases, in the regulation of a plethora of cellular processes. In general, the protein phosphatases are comprised of a catalytic subunit with one or more regulatory and/or targeting subunits associated with it. The Protein Phosphatase 2A (PP2A), a member of serine/threonine phosphatases family, is ubiquitously expressed a remarkably conserved enzyme in the cell. Its catalytic activity has been highly regulated and may have enormous therapeutic potential which is still untapped. It has specificities for a number of substrates which witnessed its involvement in various signalling modules of cell cycle regulation, cell morphology and development. Thus it can be an appropriate target for studying different diseases associated with abnormal signal transduction pathways such as neurodegenerative diseases and malignancies. This review will focus on the structure and regulatory pathways of PP2A. The de-regulation of PP2A in some specific pathology such as Cancer, Heart diseases, Neurodegenerative disorders and Diabetes will also be touched upon.
Collapse
Affiliation(s)
- Rathinasamy Baskaran
- National Institute of Cancer Research, National Health Research Institutes, Zhunan, Miaoli County, Taiwan
| | - Bharath Kumar Velmurugan
- Toxicology and Biomedicine Research Group, Faculty of Applied Sciences, Ton Duc Thang University, Ho Chi Minh City, Vietnam.
| |
Collapse
|
12
|
Göder A, Emmerich C, Nikolova T, Kiweler N, Schreiber M, Kühl T, Imhof D, Christmann M, Heinzel T, Schneider G, Krämer OH. HDAC1 and HDAC2 integrate checkpoint kinase phosphorylation and cell fate through the phosphatase-2A subunit PR130. Nat Commun 2018; 9:764. [PMID: 29472538 PMCID: PMC5823910 DOI: 10.1038/s41467-018-03096-0] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 01/19/2018] [Indexed: 12/18/2022] Open
Abstract
Checkpoint kinases sense replicative stress to prevent DNA damage. Here we show that the histone deacetylases HDAC1/HDAC2 sustain the phosphorylation of the checkpoint kinases ATM, CHK1 and CHK2, activity of the cell cycle gatekeeper kinases WEE1 and CDK1, and induction of the tumour suppressor p53 in response to stalled DNA replication. Consequently, HDAC inhibition upon replicative stress promotes mitotic catastrophe. Mechanistically, HDAC1 and HDAC2 suppress the expression of PPP2R3A/PR130, a regulatory subunit of the trimeric serine/threonine phosphatase 2 (PP2A). Genetic elimination of PR130 reveals that PR130 promotes dephosphorylation of ATM by PP2A. Moreover, the ablation of PR130 slows G1/S phase transition and increases the levels of phosphorylated CHK1, replication protein A foci and DNA damage upon replicative stress. Accordingly, stressed PR130 null cells are very susceptible to HDAC inhibition, which abrogates the S phase checkpoint, induces apoptosis and reduces the homologous recombination protein RAD51. Thus, PR130 controls cell fate decisions upon replicative stress. Checkpoint kinases control cell cycle progression via the regulation of many key regulators. Here the authors demonstrate how HDAC1 and HDAC2 modulate checkpoint kinase signalling via the suppression of PR130, a regulatory subunit of the trimeric serine/threonine phosphatase 2.
Collapse
Affiliation(s)
- Anja Göder
- Institute of Toxicology, University Medical Center Mainz, Obere Zahlbacher Strasse 67, 55131, Mainz, Germany
| | - Claudia Emmerich
- University of Jena, Institute of Biochemistry and Biophysics, Center for Molecular Biomedicine (CMB), Hans-Knöll-Strasse 2, 07745, Jena, Germany
| | - Teodora Nikolova
- Institute of Toxicology, University Medical Center Mainz, Obere Zahlbacher Strasse 67, 55131, Mainz, Germany
| | - Nicole Kiweler
- Institute of Toxicology, University Medical Center Mainz, Obere Zahlbacher Strasse 67, 55131, Mainz, Germany
| | - Maria Schreiber
- University of Jena, Institute of Biochemistry and Biophysics, Center for Molecular Biomedicine (CMB), Hans-Knöll-Strasse 2, 07745, Jena, Germany
| | - Toni Kühl
- Pharmaceutical Biochemistry and Bioanalytics, Pharmaceutical Institute, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany
| | - Diana Imhof
- Pharmaceutical Biochemistry and Bioanalytics, Pharmaceutical Institute, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany
| | - Markus Christmann
- Institute of Toxicology, University Medical Center Mainz, Obere Zahlbacher Strasse 67, 55131, Mainz, Germany
| | - Thorsten Heinzel
- University of Jena, Institute of Biochemistry and Biophysics, Center for Molecular Biomedicine (CMB), Hans-Knöll-Strasse 2, 07745, Jena, Germany
| | - Günter Schneider
- Klinik und Poliklinik für Innere Medizin II, Technical University of Munich, Ismaningerstrasse 22, 81675, Munich, Germany
| | - Oliver H Krämer
- Institute of Toxicology, University Medical Center Mainz, Obere Zahlbacher Strasse 67, 55131, Mainz, Germany.
| |
Collapse
|
13
|
Zhao H, Li D, Zhang B, Qi Y, Diao Y, Zhen Y, Shu X. PP2A as the Main Node of Therapeutic Strategies and Resistance Reversal in Triple-Negative Breast Cancer. Molecules 2017; 22:molecules22122277. [PMID: 29261144 PMCID: PMC6149800 DOI: 10.3390/molecules22122277] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 12/07/2017] [Accepted: 12/19/2017] [Indexed: 12/31/2022] Open
Abstract
Triple negative breast cancer (TNBC), is defined as a type of tumor lacking the expression of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2). The ER, PR and HER2 are usually the molecular therapeutic targets for breast cancers, but they are ineffective for TNBC because of their negative expressions, so chemotherapy is currently the main treatment strategy in TNBC. However, drug resistance remains a major impediment to TNBC chemotherapeutic treatment. Recently, the protein phosphatase 2A (PP2A) has been found to regulate the phosphorylation of some substrates involved in the relevant target of TNBC, such as cell cycle control, DNA damage responses, epidermal growth factor receptor, immune modulation and cell death resistance, which may be the effective therapeutic strategies or influence drug sensitivity to TNBCs. Furthermore, PP2A has also been found that could induce ER re-expression in ER-negative breast cancer cells, and which suggests PP2A could promote the sensitivity of tamoxifen to TNBCs as a resistance reversal agent. In this review, we will summarize the potential therapeutic value of PP2A as the main node in developing targeting agents, disrupting resistance or restoring drug sensitivity in TNBC.
Collapse
Affiliation(s)
- Henan Zhao
- Department of Pathophysiology, Dalian Medical University, Dalian 116044, China.
| | - Duojiao Li
- Kamp Pharmaceutical Co. Ltd., Changsha 410008, China.
| | - Baojing Zhang
- College of Pharmacy, Dalian Medical University, Dalian 116044, China.
| | - Yan Qi
- College of Pharmacy, Dalian Medical University, Dalian 116044, China.
| | - Yunpeng Diao
- College of Pharmacy, Dalian Medical University, Dalian 116044, China.
| | - Yuhong Zhen
- College of Pharmacy, Dalian Medical University, Dalian 116044, China.
| | - Xiaohong Shu
- College of Pharmacy, Dalian Medical University, Dalian 116044, China.
| |
Collapse
|
14
|
Meeusen B, Janssens V. Tumor suppressive protein phosphatases in human cancer: Emerging targets for therapeutic intervention and tumor stratification. Int J Biochem Cell Biol 2017; 96:98-134. [PMID: 29031806 DOI: 10.1016/j.biocel.2017.10.002] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2017] [Revised: 10/04/2017] [Accepted: 10/05/2017] [Indexed: 02/06/2023]
Abstract
Aberrant protein phosphorylation is one of the hallmarks of cancer cells, and in many cases a prerequisite to sustain tumor development and progression. Like protein kinases, protein phosphatases are key regulators of cell signaling. However, their contribution to aberrant signaling in cancer cells is overall less well appreciated, and therefore, their clinical potential remains largely unexploited. In this review, we provide an overview of tumor suppressive protein phosphatases in human cancer. Along their mechanisms of inactivation in defined cancer contexts, we give an overview of their functional roles in diverse signaling pathways that contribute to their tumor suppressive abilities. Finally, we discuss their emerging roles as predictive or prognostic markers, their potential as synthetic lethality targets, and the current feasibility of their reactivation with pharmacologic compounds as promising new cancer therapies. We conclude that their inclusion in clinical practice has obvious potential to significantly improve therapeutic outcome in various ways, and should now definitely be pushed forward.
Collapse
Affiliation(s)
- Bob Meeusen
- Laboratory of Protein Phosphorylation & Proteomics, Dept. of Cellular & Molecular Medicine, Faculty of Medicine, KU Leuven & Leuven Cancer Institute (LKI), KU Leuven, Belgium
| | - Veerle Janssens
- Laboratory of Protein Phosphorylation & Proteomics, Dept. of Cellular & Molecular Medicine, Faculty of Medicine, KU Leuven & Leuven Cancer Institute (LKI), KU Leuven, Belgium.
| |
Collapse
|
15
|
The serine/threonine protein phosphatase 2A controls autoimmunity. Clin Immunol 2017; 186:38-42. [PMID: 28736280 DOI: 10.1016/j.clim.2017.07.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 07/19/2017] [Indexed: 12/16/2022]
Abstract
Protein phosphatase 2A (PP2A) is the first serine/threonine phosphatase recognized to contribute to human and murine lupus immunopathology. PP2A expression in SLE is controlled both epigenetically and genetically, and it is increased in patients with SLE, which contributes to decreased IL-2 production, decreased CD3ζ and increased FcRγ expression on the surface of T cells, increased CREMα expression, hypomethylation of genes associated with SLE pathogenesis, and increased IL-17 production. β regulatory subunit of PP2A regulates IL-2 deprivation-induced T cell death and is decreased in SLE patients. A mouse overexpressing PP2Ac in T cells displays peripheral granulocytosis, elevated IL-17 production, and develops glomerulonephritis when challenged. A mouse which lacks PP2Ac only in regulatory T cells develops severe autoimmunity and multiorgan inflammation because of loss of restraint on mTORC1 and inability of Foxp3+ cells to regulate conventional T cells. Targeting PP2A in T cell subsets may be therapeutic for SLE and other autoimmune diseases.
Collapse
|
16
|
Protein Phosphatase 2A: a Double-Faced Phosphatase of Cellular System and Its Role in Neurodegenerative Disorders. Mol Neurobiol 2017; 55:1750-1761. [PMID: 28224476 DOI: 10.1007/s12035-017-0444-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 02/03/2017] [Indexed: 12/17/2022]
Abstract
Protein phosphatase 2A (PP2A), a ubiquitously expressed serine/threonine phosphatase, is a vitally important phosphatase for the cellular system. Structurally, it is constituted of three different subunits, namely catalytic subunit (PP2Ac), structural scaffold subunit (PP2A-A), and regulatory subunit (PP2A-B). All subunits have various isoforms, and catalytic and scaffold subunits are ubiquitously expressed, whereas regulatory subunits are more specific to tissue and cell type. It is the numerous possibilities of PP2A holoenzyme assembly with varying isoform components that make it possess a dual nature of activator or the inhibitory character in different signaling pathways, namely neural developmental pathways, Akt/protein kinase B pathway, NF-kB pathway, MAPK pathway, apoptosis pathway, and cell cycle progression to name a few. Importantly, the expression of PP2A in the brain is highest among the serine phosphatases and is known to actively participate in the neural development process. However, the exact mechanism of action of PP2A is still debated and enunciating the holoenzyme components, especially the regulatory subunit of PP2A involved in regulating neural developmental process is still poorly understood. In this review, we try to throw some light on the involvement of various PP2A holoenzyme forms in the process of neurogenesis and progression of neurodegenerative diseases.
Collapse
|
17
|
Thomas MP, Erneux C, Potter BVL. SHIP2: Structure, Function and Inhibition. Chembiochem 2017; 18:233-247. [DOI: 10.1002/cbic.201600541] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Indexed: 11/10/2022]
Affiliation(s)
- Mark P. Thomas
- Department of Pharmacy and Pharmacology; University of Bath; Claverton Down Bath BA2 7AY UK
| | - Christophe Erneux
- I.R.I.B.H.M.; Université Libre de Bruxelles; Campus Erasme 808 Route de Lennik 1070 Brussels Belgium
| | - Barry V. L. Potter
- Drug Discovery and Medicinal Chemistry; Department of Pharmacology; University of Oxford; Mansfield Road Oxford OX1 3QT UK
| |
Collapse
|
18
|
The broken "Off" switch in cancer signaling: PP2A as a regulator of tumorigenesis, drug resistance, and immune surveillance. BBA CLINICAL 2016; 6:87-99. [PMID: 27556014 PMCID: PMC4986044 DOI: 10.1016/j.bbacli.2016.08.002] [Citation(s) in RCA: 112] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/02/2016] [Revised: 08/01/2016] [Accepted: 08/02/2016] [Indexed: 12/31/2022]
Abstract
Aberrant activation of signal transduction pathways can transform a normal cell to a malignant one and can impart survival properties that render cancer cells resistant to therapy. A diverse set of cascades have been implicated in various cancers including those mediated by serine/threonine kinases such RAS, PI3K/AKT, and PKC. Signal transduction is a dynamic process involving both "On" and "Off" switches. Activating mutations of RAS or PI3K can be viewed as the switch being stuck in the "On" position resulting in continued signaling by a survival and/or proliferation pathway. On the other hand, inactivation of protein phosphatases such as the PP2A family can be seen as the defective "Off" switch that similarly can activate these pathways. A problem for therapeutic targeting of PP2A is that the enzyme is a hetero-trimer and thus drug targeting involves complex structures. More importantly, since PP2A isoforms generally act as tumor suppressors one would want to activate these enzymes rather than suppress them. The elucidation of the role of cellular inhibitors like SET and CIP2A in cancer suggests that targeting these proteins can have therapeutic efficacy by mechanisms involving PP2A activation. Furthermore, drugs such as FTY-720 can activate PP2A isoforms directly. This review will cover the current state of knowledge of PP2A role as a tumor suppressor in cancer cells and as a mediator of processes that can impact drug resistance and immune surveillance.
Collapse
|
19
|
Haesen D, Abbasi Asbagh L, Derua R, Hubert A, Schrauwen S, Hoorne Y, Amant F, Waelkens E, Sablina A, Janssens V. Recurrent PPP2R1A Mutations in Uterine Cancer Act through a Dominant-Negative Mechanism to Promote Malignant Cell Growth. Cancer Res 2016; 76:5719-5731. [PMID: 27485451 DOI: 10.1158/0008-5472.can-15-3342] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 07/14/2016] [Indexed: 11/16/2022]
Abstract
Somatic missense mutations in the Ser/Thr protein phosphatase 2A (PP2A) Aα scaffold subunit gene PPP2R1A are among the few genomic alterations that occur frequently in serous endometrial carcinoma (EC) and carcinosarcoma, two clinically aggressive subtypes of uterine cancer with few therapeutic options. Previous studies reported that cancer-associated Aα mutants exhibit defects in binding to other PP2A subunits and contribute to cancer development by a mechanism of haploinsufficiency. Here we report on the functional significance of the most recurrent PPP2R1A mutations in human EC, which cluster in Aα HEAT repeats 5 and 7. Beyond predicted loss-of-function effects on the formation of a subset of PP2A holoenzymes, we discovered that Aα mutants behave in a dominant-negative manner due to gain-of-function interactions with the PP2A inhibitor TIPRL1. Dominant-negative Aα mutants retain binding to specific subunits of the B56/B' family and form substrate trapping complexes with impaired phosphatase activity via increased recruitment of TIPRL1. Accordingly, overexpression of the Aα mutants in EC cells harboring wild-type PPP2R1A increased anchorage-independent growth and tumor formation, and triggered hyperphosphorylation of oncogenic PP2A-B56/B' substrates in the GSK3β, Akt, and mTOR/p70S6K signaling pathways. TIPRL1 silencing restored GSK3β phosphorylation and rescued the EC cell growth advantage. Our results reveal how PPP2R1A mutations affect PP2A function and oncogenic signaling, illuminating the genetic basis for serous EC development and its potential control by rationally targeted therapies. Cancer Res; 76(19); 5719-31. ©2016 AACR.
Collapse
Affiliation(s)
- Dorien Haesen
- Laboratory of Protein Phosphorylation and Proteomics, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Layka Abbasi Asbagh
- VIB Center for the Biology of Disease, Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Rita Derua
- Laboratory of Protein Phosphorylation and Proteomics, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Antoine Hubert
- Laboratory of Protein Phosphorylation and Proteomics, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Stefanie Schrauwen
- Laboratory of Gynaecological Oncology, Department of Oncology, KU Leuven, Leuven, Belgium
| | - Yana Hoorne
- Laboratory of Protein Phosphorylation and Proteomics, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Frédéric Amant
- Laboratory of Gynaecological Oncology, Department of Oncology, KU Leuven, Leuven, Belgium
| | - Etienne Waelkens
- Laboratory of Protein Phosphorylation and Proteomics, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Anna Sablina
- VIB Center for the Biology of Disease, Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Veerle Janssens
- Laboratory of Protein Phosphorylation and Proteomics, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium.
| |
Collapse
|
20
|
Janssens V, Zwaenepoel K, Rossé C, Petit MMR, Goris J, Parker PJ. PP2A binds to the LIM domains of lipoma-preferred partner through its PR130/B″ subunit to regulate cell adhesion and migration. J Cell Sci 2016; 129:1605-18. [PMID: 26945059 PMCID: PMC5333791 DOI: 10.1242/jcs.175778] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2015] [Accepted: 02/18/2016] [Indexed: 01/23/2023] Open
Abstract
Here, we identify the LIM protein lipoma-preferred partner (LPP) as a binding partner of a specific protein phosphatase 2A (PP2A) heterotrimer that is characterised by the regulatory PR130/B″α1 subunit (encoded by PPP2R3A). The PR130 subunit interacts with the LIM domains of LPP through a conserved Zn²⁺-finger-like motif in the differentially spliced N-terminus of PR130. Isolated LPP-associated PP2A complexes are catalytically active. PR130 colocalises with LPP at multiple locations within cells, including focal contacts, but is specifically excluded from mature focal adhesions, where LPP is still present. An LPP-PR130 fusion protein only localises to focal adhesions upon deletion of the domain of PR130 that binds to the PP2A catalytic subunit (PP2A/C), suggesting that PR130-LPP complex formation is dynamic and that permanent recruitment of PP2A activity might be unfavourable for focal adhesion maturation. Accordingly, siRNA-mediated knockdown of PR130 increases adhesion of HT1080 fibrosarcoma cells onto collagen I and decreases their migration in scratch wound and Transwell assays. Complex formation with LPP is mandatory for these PR130-PP2A functions, as neither phenotype can be rescued by re-expression of a PR130 mutant that no longer binds to LPP. Our data highlight the importance of specific, locally recruited PP2A complexes in cell adhesion and migration dynamics.
Collapse
Affiliation(s)
- Veerle Janssens
- Francis Crick Institute, Protein Phosphorylation Laboratory, 44 Lincoln's Inn Fields, London WC2A 3PX, UK Laboratory of Protein Phosphorylation and Proteomics, Dept. of Cellular and Molecular Medicine, KU Leuven, Herestraat 49 PO-box 901, Leuven B-3000, Belgium
| | - Karen Zwaenepoel
- Laboratory of Protein Phosphorylation and Proteomics, Dept. of Cellular and Molecular Medicine, KU Leuven, Herestraat 49 PO-box 901, Leuven B-3000, Belgium
| | - Carine Rossé
- Francis Crick Institute, Protein Phosphorylation Laboratory, 44 Lincoln's Inn Fields, London WC2A 3PX, UK Research Centre, Institut Curie, Paris 75005, France
| | - Marleen M R Petit
- Molecular Oncology Laboratory, Dept. of Human Genetics, KU Leuven, Herestraat 49 PO-box 602, Leuven B-3000, Belgium
| | - Jozef Goris
- Laboratory of Protein Phosphorylation and Proteomics, Dept. of Cellular and Molecular Medicine, KU Leuven, Herestraat 49 PO-box 901, Leuven B-3000, Belgium
| | - Peter J Parker
- Francis Crick Institute, Protein Phosphorylation Laboratory, 44 Lincoln's Inn Fields, London WC2A 3PX, UK Division of Cancer Studies King's College London, Guy's Hospital Campus, Thomas Street, London SE1 9RT, UK
| |
Collapse
|
21
|
Arriazu E, Pippa R, Odero MD. Protein Phosphatase 2A as a Therapeutic Target in Acute Myeloid Leukemia. Front Oncol 2016; 6:78. [PMID: 27092295 PMCID: PMC4822158 DOI: 10.3389/fonc.2016.00078] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 03/21/2016] [Indexed: 12/31/2022] Open
Abstract
Acute myeloid leukemia (AML) is a heterogeneous malignant disorder of hematopoietic progenitor cells in which several genetic and epigenetic aberrations have been described. Despite progressive advances in our understanding of the molecular biology of this disease, the outcome for most patients is poor. It is, therefore, necessary to develop more effective treatment strategies. Genetic aberrations affecting kinases have been widely studied in AML; however, the role of phosphatases remains underexplored. Inactivation of the tumor-suppressor protein phosphatase 2A (PP2A) is frequent in AML patients, making it a promising target for therapy. There are several PP2A inactivating mechanisms reported in this disease. Deregulation or specific post-translational modifications of PP2A subunits have been identified as a cause of PP2A malfunction, which lead to deregulation of proliferation or apoptosis pathways, depending on the subunit affected. Likewise, overexpression of either SET or cancerous inhibitor of protein phosphatase 2A, endogenous inhibitors of PP2A, is a recurrent event in AML that impairs PP2A activity, contributing to leukemogenesis progression. Interestingly, the anticancer activity of several PP2A-activating drugs (PADs) depends on interaction/sequestration of SET. Preclinical studies show that pharmacological restoration of PP2A activity by PADs effectively antagonizes leukemogenesis, and that these drugs have synergistic cytotoxic effects with conventional chemotherapy and kinase inhibitors, opening new possibilities for personalized treatment in AML patients, especially in cases with SET-dependent inactivation of PP2A. Here, we review the role of PP2A as a druggable tumor suppressor in AML.
Collapse
Affiliation(s)
- Elena Arriazu
- Hematology/Oncology Program, Center for Applied Medical Research (CIMA), University of Navarra , Pamplona , Spain
| | - Raffaella Pippa
- Centre for Gene Regulation and Expression, University of Dundee , Dundee , UK
| | - María D Odero
- Hematology/Oncology Program, Center for Applied Medical Research (CIMA), University of Navarra, Pamplona, Spain; Department of Biochemistry and Genetics, University of Navarra, Pamplona, Spain; Instituto de Investigación Sanitaria de Navarra (IdiSNA), Pamplona, Spain
| |
Collapse
|
22
|
Zhang X, Damacharla D, Ma D, Qi Y, Tagett R, Draghici S, Kowluru A, Yi Z. Quantitative proteomics reveals novel protein interaction partners of PP2A catalytic subunit in pancreatic β-cells. Mol Cell Endocrinol 2016; 424:1-11. [PMID: 26780722 PMCID: PMC4779412 DOI: 10.1016/j.mce.2016.01.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 12/15/2015] [Accepted: 01/07/2016] [Indexed: 12/19/2022]
Abstract
Protein phosphatase 2A (PP2A) is one of the major serine/threonine phosphatases. We hypothesize that PP2A regulates signaling cascades in pancreatic β-cells in the context of glucose-stimulated insulin secretion (GSIS). Using co-immunoprecipitation (co-IP) and tandem mass spectrometry, we globally identified the protein interaction partners of the PP2A catalytic subunit (PP2Ac) in insulin-secreting pancreatic β-cells. Among the 514 identified PP2Ac interaction partners, 476 were novel. This represents the first global view of PP2Ac protein-protein interactions caused by hyperglycemic conditions. Additionally, numerous PP2Ac partners were found involved in a variety of signaling pathways in the β-cell function, such as insulin secretion. Our data suggest that PP2A interacts with various signaling proteins necessary for physiological insulin secretion as well as signaling proteins known to regulate cell dysfunction and apoptosis in the pancreatic β-cells.
Collapse
Affiliation(s)
- Xiangmin Zhang
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, 48201, USA
| | - Divyasri Damacharla
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, 48201, USA
| | - Danjun Ma
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, 48201, USA
| | - Yue Qi
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, 48201, USA
| | - Rebecca Tagett
- Department of Computer Science, College of Engineering, Wayne State University, Detroit, MI, USA
| | - Sorin Draghici
- Department of Computer Science, College of Engineering, Wayne State University, Detroit, MI, USA
| | - Anjaneyulu Kowluru
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, 48201, USA; β-Cell Biochemistry Laboratory, John D. Dingell VA Medical Center, Detroit, MI, 48201, USA
| | - Zhengping Yi
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, 48201, USA.
| |
Collapse
|
23
|
Abstract
Protein phosphatase 2A (PP2A) plays a critical multi-faceted role in the regulation of the cell cycle. It is known to dephosphorylate over 300 substrates involved in the cell cycle, regulating almost all major pathways and cell cycle checkpoints. PP2A is involved in such diverse processes by the formation of structurally distinct families of holoenzymes, which are regulated spatially and temporally by specific regulators. Here, we review the involvement of PP2A in the regulation of three cell signaling pathways: wnt, mTOR and MAP kinase, as well as the G1→S transition, DNA synthesis and mitotic initiation. These processes are all crucial for proper cell survival and proliferation and are often deregulated in cancer and other diseases.
Collapse
Affiliation(s)
- Nathan Wlodarchak
- a McArdle Laboratory for Cancer Research, University of Wisconsin-Madison , Madison , WI , USA
| | - Yongna Xing
- a McArdle Laboratory for Cancer Research, University of Wisconsin-Madison , Madison , WI , USA
| |
Collapse
|
24
|
Inhibition of Receptor Dimerization as a Novel Negative Feedback Mechanism of EGFR Signaling. PLoS One 2015; 10:e0139971. [PMID: 26465157 PMCID: PMC4605717 DOI: 10.1371/journal.pone.0139971] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 09/18/2015] [Indexed: 11/19/2022] Open
Abstract
Dimerization of the epidermal growth factor receptor (EGFR) is crucial for initiating signal transduction. We employed raster image correlation spectroscopy to continuously monitor the EGFR monomer-dimer equilibrium in living cells. EGFR dimer formation upon addition of EGF showed oscillatory behavior with a periodicity of about 2.5 min, suggesting the presence of a negative feedback loop to monomerize the receptor. We demonstrated that monomerization of EGFR relies on phospholipase Cγ, protein kinase C, and protein kinase D (PKD), while being independent of Ca2+ signaling and endocytosis. Phosphorylation of the juxtamembrane threonine residues of EGFR (T654/T669) by PKD was identified as the factor that shifts the monomer-dimer equilibrium of ligand bound EGFR towards the monomeric state. The dimerization state of the receptor correlated with the activity of an extracellular signal-regulated kinase, downstream of the EGFR. Based on these observations, we propose a novel, negative feedback mechanism that regulates EGFR signaling via receptor monomerization.
Collapse
|
25
|
Davis WJ, Lehmann PZ, Li W. Nuclear PI3K signaling in cell growth and tumorigenesis. Front Cell Dev Biol 2015; 3:24. [PMID: 25918701 PMCID: PMC4394695 DOI: 10.3389/fcell.2015.00024] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2014] [Accepted: 03/27/2015] [Indexed: 12/12/2022] Open
Abstract
The PI3K/Akt signaling pathway is a major driving force in a variety of cellular functions. Dysregulation of this pathway has been implicated in many human diseases including cancer. While the activity of the cytoplasmic PI3K/Akt pathway has been extensively studied, the functions of these molecules and their effector proteins within the nucleus are poorly understood. Harboring key cellular processes such as DNA replication and repair as well as nascent messenger RNA transcription, the nucleus provides a unique compartmental environment for protein–protein and protein–DNA/RNA interactions required for cell survival, growth, and proliferation. Here we summarize recent advances made toward elucidating the nuclear PI3K/Akt signaling cascade and its key components within the nucleus as they pertain to cell growth and tumorigenesis. This review covers the spatial and temporal localization of the major nuclear kinases having PI3K activities and the counteracting phosphatases as well as the role of nuclear PI3K/Akt signaling in mRNA processing and exportation, DNA replication and repair, ribosome biogenesis, cell survival, and tumorigenesis.
Collapse
Affiliation(s)
- William J Davis
- College of Medical Sciences, Washington State University Spokane, WA, USA
| | - Peter Z Lehmann
- College of Medical Sciences, Washington State University Spokane, WA, USA
| | - Weimin Li
- College of Medical Sciences, Washington State University Spokane, WA, USA
| |
Collapse
|
26
|
Suzuki OT, Frick A, Parks BB, Trask OJ, Butz N, Steffy B, Chan E, Scoville DK, Healy E, Benton C, McQuaid PE, Thomas RS, Wiltshire T. A cellular genetics approach identifies gene-drug interactions and pinpoints drug toxicity pathway nodes. Front Genet 2014; 5:272. [PMID: 25221565 PMCID: PMC4148776 DOI: 10.3389/fgene.2014.00272] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Accepted: 07/24/2014] [Indexed: 12/03/2022] Open
Abstract
New approaches to toxicity testing have incorporated high-throughput screening across a broad-range of in vitro assays to identify potential key events in response to chemical or drug treatment. To date, these approaches have primarily utilized repurposed drug discovery assays. In this study, we describe an approach that combines in vitro screening with genetic approaches for the experimental identification of genes and pathways involved in chemical or drug toxicity. Primary embryonic fibroblasts isolated from 32 genetically-characterized inbred mouse strains were treated in concentration-response format with 65 compounds, including pharmaceutical drugs, environmental chemicals, and compounds with known modes-of-action. Integrated cellular responses were measured at 24 and 72 h using high-content imaging and included cell loss, membrane permeability, mitochondrial function, and apoptosis. Genetic association analysis of cross-strain differences in the cellular responses resulted in a collection of candidate loci potentially underlying the variable strain response to each chemical. As a demonstration of the approach, one candidate gene involved in rotenone sensitivity, Cybb, was experimentally validated in vitro and in vivo. Pathway analysis on the combined list of candidate loci across all chemicals identified a number of over-connected nodes that may serve as core regulatory points in toxicity pathways.
Collapse
Affiliation(s)
- Oscar T Suzuki
- Division of Pharmacotherapy and Experimental Therapeutics, UNC Eshelman School of Pharmacy at the University of North Carolina at Chapel Hill Chapel Hill, NC, USA
| | - Amber Frick
- Division of Pharmacotherapy and Experimental Therapeutics, UNC Eshelman School of Pharmacy at the University of North Carolina at Chapel Hill Chapel Hill, NC, USA
| | - Bethany B Parks
- The Hamner Institutes for Health Sciences, Research Triangle Park NC, USA
| | - O Joseph Trask
- The Hamner Institutes for Health Sciences, Research Triangle Park NC, USA
| | - Natasha Butz
- Division of Pharmacotherapy and Experimental Therapeutics, UNC Eshelman School of Pharmacy at the University of North Carolina at Chapel Hill Chapel Hill, NC, USA
| | - Brian Steffy
- Division of Pharmacotherapy and Experimental Therapeutics, UNC Eshelman School of Pharmacy at the University of North Carolina at Chapel Hill Chapel Hill, NC, USA
| | - Emmanuel Chan
- Division of Pharmacotherapy and Experimental Therapeutics, UNC Eshelman School of Pharmacy at the University of North Carolina at Chapel Hill Chapel Hill, NC, USA
| | - David K Scoville
- Division of Pharmacotherapy and Experimental Therapeutics, UNC Eshelman School of Pharmacy at the University of North Carolina at Chapel Hill Chapel Hill, NC, USA
| | - Eric Healy
- The Hamner Institutes for Health Sciences, Research Triangle Park NC, USA
| | - Cristina Benton
- Division of Pharmacotherapy and Experimental Therapeutics, UNC Eshelman School of Pharmacy at the University of North Carolina at Chapel Hill Chapel Hill, NC, USA
| | | | - Russell S Thomas
- The Hamner Institutes for Health Sciences, Research Triangle Park NC, USA
| | - Tim Wiltshire
- Division of Pharmacotherapy and Experimental Therapeutics, UNC Eshelman School of Pharmacy at the University of North Carolina at Chapel Hill Chapel Hill, NC, USA
| |
Collapse
|
27
|
Gabitova L, Gorin A, Astsaturov I. Molecular pathways: sterols and receptor signaling in cancer. Clin Cancer Res 2013; 20:28-34. [PMID: 24158702 DOI: 10.1158/1078-0432.ccr-13-0122] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Accelerated cholesterol and lipid metabolism are the hallmarks of cancer and contribute to malignant transformation due to the obligatory requirement for cholesterol for the function of eukaryotic membranes. To build new membranes and maintain active signaling, cancer cells depend on high intensity of endogenous cholesterol biosynthesis and uptake of lipid particles. This metabolic dependency of cancer cells on cholesterol and other lipids is tightly regulated by the cholesterol homeostasis network, including (i) sterol response element-binding proteins (SREBP), master transcriptional regulators of cholesterol and fatty acid pathway genes; (ii) nuclear sterol receptors (liver X receptors, LXR), which coordinate growth with the availability of cholesterol; and (iii) lipid particle receptors, such as low-density lipid particle (LDL) receptor, providing exogenous sterol and lipids to cancer cells. In addition, activity of oncogenic receptors, such as MUC1 or EGFR, accelerates sterol uptake and biosynthesis. Therefore, a general strategy of reducing the cholesterol pool in cancer cells is challenged by the highly efficient feedback loops compensating for a blockade at a single point in the cholesterol homeostatic network. Besides the well-established structural role of cholesterol in membranes, recent studies have uncovered potent biologic activities of certain cholesterol metabolic precursors and its oxidized derivatives, oxysterols. The former, meiosis-activating sterols, exert effects on trafficking and signaling of oncogenic EGF receptor (EGFR). Cholesterol epoxides, the highly active products of cholesterol oxidation, are being neutralized by the distal sterol pathway enzymes, emopamyl-binding protein (EBP) and dehydrocholesterol-7 reductase (DHCR7). These recently discovered "moonlighting" activities of the cholesterol pathway genes and metabolites expand our understanding of the uniquely conserved roles these sterol molecules play in the regulation of cellular proliferation and in cancer.
Collapse
Affiliation(s)
- Linara Gabitova
- Authors' Affiliations: Program in Developmental Therapeutics, Fox Chase Cancer Center, Philadelphia, Pennsylvania; Kazan Federal University, Republic of Tatarstan, Russia
| | | | | |
Collapse
|
28
|
Awad A, Sar S, Barré R, Cariven C, Marin M, Salles JP, Erneux C, Samuel D, Gassama-Diagne A. SHIP2 regulates epithelial cell polarity through its lipid product, which binds to Dlg1, a pathway subverted by hepatitis C virus core protein. Mol Biol Cell 2013; 24:2171-85. [PMID: 23699395 PMCID: PMC3708724 DOI: 10.1091/mbc.e12-08-0626] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The main targets of hepatitis C virus (HCV) are hepatocytes, the highly polarized cells of the liver, and all the steps of its life cycle are tightly dependent on host lipid metabolism. The interplay between polarity and lipid metabolism in HCV infection has been poorly investigated. Signaling lipids, such as phosphoinositides (PIs), play a vital role in polarity, which depends on the distribution and expression of PI kinases and PI phosphatases. In this study, we report that HCV core protein, expressed in Huh7 and Madin-Darby canine kidney (MDCK) cells, disrupts apicobasal polarity. This is associated with decreased expression of the polarity protein Dlg1 and the PI phosphatase SHIP2, which converts phosphatidylinositol 3,4,5-trisphosphate into phosphatidylinositol 4,5-bisphosphate (PtdIns(3,4)P2). SHIP2 is mainly localized at the basolateral membrane of polarized MDCK cells. In addition, PtdIns(3,4)P2 is able to bind to Dlg1. SHIP2 small interfering RNA or its catalytically dead mutant disrupts apicobasal polarity, similar to HCV core. In core-expressing cells, RhoA activity is inhibited, whereas Rac1 is activated. Of interest, SHIP2 expression rescues polarity, RhoA activation, and restricted core level in MDCK cells. We conclude that SHIP2 is an important regulator of polarity, which is subverted by HCV in epithelial cells. It is suggested that SHIP2 could be a promising target for anti-HCV treatment.
Collapse
Affiliation(s)
- Aline Awad
- Université Paris-Sud, UMR-S 785, F-94800 Villejuif, France
| | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Xie J, Erneux C, Pirson I. How does SHIP1/2 balance PtdIns(3,4)P2 and does it signal independently of its phosphatase activity? Bioessays 2013; 35:733-43. [PMID: 23650141 DOI: 10.1002/bies.201200168] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The number of cellular events identified as being directly or indirectly modulated by phosphoinositides dramatically increased in the recent years. Part of the complexity results from the fact that the seven phosphoinositides play second messenger functions in many different areas of growth factors and insulin signaling, cytoskeletal organization, membrane dynamics, trafficking, or nuclear signaling. PtdIns(3,4)P2 is commonly reported as a product of the SH2 domain-containing inositol 5-phosphatases 1/2 (SHIP1 and SHIP2) that dephosphorylate PtdIns(3,4,5)P3 at the 5-position. Here we discuss recent interest in PtdIns(3,4)P2 signaling highlighting its involvement in key cellular mechanisms such as cell adhesion, migration, and cytoskeletal regulation. We question and discuss the involvement of SHIP2 either as a PI 5-phosphatase or as a scaffold protein in insulin signaling, cytoskeletal dynamics, and endocytosis of growth factor receptors.
Collapse
Affiliation(s)
- Jingwei Xie
- Department of Pathophysiology, China Medical University, Heping District, Shenyang Liaoning Province, China
| | | | | |
Collapse
|
30
|
Abstract
A recently discovered protein phosphatase PHLPP (PH domain Leucine-rich repeat Protein Phosphatase) has been shown to dephosphorylate Akt on its hydrophobic motif (Ser473) thereby decreasing Akt kinase activity. We generated PHLPP1 knockout (KO) mice and used them to explore the ability of enhanced in vivo Akt signaling to protect the brain against ischemic insult. Brains from KO mice subjected to middle cerebral artery occlusion (MCAO) for 2 hours showed significantly greater increases in Akt activity and less neurovascular damage after reperfusion than wild-type (WT) mice. Remarkably, infarct volume in the PHLPP1 KO was significantly reduced compared with WT (12.7±2.7% versus 22.9±3.1%) and this was prevented by Akt inhibition. Astrocytes from KO mice and neurons in which PHLPP1 was downregulated showed enhanced Akt activation and diminished cell death in response to oxygen-glucose deprivation. Thus, deletion of PHLPP1 can enhance Akt activation in neurons and astrocytes, and can significantly increase cell survival and diminish infarct size after MCAO. Inhibition of PHLPP could be a therapeutic approach to minimize damage after focal ischemia.
Collapse
|
31
|
Elong Edimo W, Vanderwinden JM, Erneux C. SHIP2 signalling at the plasma membrane, in the nucleus and at focal contacts. Adv Biol Regul 2013; 53:28-37. [PMID: 23040614 DOI: 10.1016/j.jbior.2012.09.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Accepted: 09/04/2012] [Indexed: 06/01/2023]
Abstract
Phosphoinositide 5-phosphatases are critical enzymes in modulating the concentrations of PI(3,4,5)P(3), PI(4,5)P(2) and PI(3,5)P(2). The SH2 domain containing inositol 5-phosphatases SHIP1 and SHIP2 belong to this family of enzymes very much involved in physiopathology and development. Therefore activity and localization of the enzymes are particularly important taking into account both catalytic and non-catalytic mechanisms of the SHIP phosphatases. Several different mechanisms have been reported for SHIP2 targeting that often result from specific protein:protein interactions. In unstimulated astrocytoma cells, SHIP2 has a perinuclear and cytoplasmic localization. In serum-stimulated cells, SHIP2 can be localized at the plasma membrane and at focal contacts in polarized cells. A phosphorylated form of SHIP2 on S132 can be found in the nucleus and nuclear speckles. When present at the plasma membrane, SHIP2 may control the intracellular level of PI(3,4,5)P(3) thereby producing PI(3,4)P(2). When present in the nucleus, SHIP2 probably associates to other nuclear proteins such as lamin A/C and could potentially control nuclear PI(4,5)P(2). Finally, its presence at focal adhesions and lamellipodia could suggest a role in cell adhesion and migration. It is proposed that the complex phenotype observed in SHIP2 mutant mice in tissue development and growth could result from the addition of plasma membrane and nuclear effects consecutive to SHIP2 alteration.
Collapse
Affiliation(s)
- William's Elong Edimo
- Interdisciplinary Research Institute (IRIBHM), Université Libre de Bruxelles, Campus Erasme, Bldg. C, 808 Route de Lennik, 1070 Brussels, Belgium
| | | | | |
Collapse
|
32
|
Abstract
Protein phosphatases of the type 2A family (PP2A) represent a major fraction of cellular Ser/Thr phosphatase activity in any given human tissue. In this review, we describe how the holoenzymic nature of PP2A and the existence of several distinct PP2A composing subunits allow for the generation of multiple structurally and functionally different PP2A complexes, explaining why PP2A is involved in the regulation of so many diverse cell biological and physiological processes. Moreover, in human disease, most notably in several cancers and Alzheimer's Disease, PP2A expression and/or activity have been found significantly decreased, underscoring its important functions as a major tumor suppressor and tau phosphatase. Hence, several recent preclinical studies have demonstrated that pharmacological restoration of PP2A activity, as well as pharmacological PP2A inhibition, under certain conditions, may be of significant future therapeutic value.
Collapse
|
33
|
Blunt MD, Ward SG. Pharmacological targeting of phosphoinositide lipid kinases and phosphatases in the immune system: success, disappointment, and new opportunities. Front Immunol 2012; 3:226. [PMID: 22876243 PMCID: PMC3410520 DOI: 10.3389/fimmu.2012.00226] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Accepted: 07/12/2012] [Indexed: 12/24/2022] Open
Abstract
The predominant expression of the γ and δ isoforms of PI3K in cells of hematopoietic lineage prompted speculation that inhibitors of these isoforms could offer opportunities for selective targeting of PI3K in the immune system in a range of immune-related pathologies. While there has been some success in developing PI3Kδ inhibitors, progress in developing selective inhibitors of PI3Kγ has been rather disappointing. This has prompted the search for alternative targets with which to modulate PI3K signaling specifically in the immune system. One such target is the SH2 domain-containing inositol-5-phosphatase-1 (SHIP-1) which de-phosphorylates PI(3,4,5)P3 at the D5 position of the inositol ring to create PI(3,4)P2. In this article, we first describe the current state of PI3K isoform-selective inhibitor development. We then focus on the structure of SHIP-1 and its function in the immune system. Finally, we consider the current state of development of small molecule compounds that potently and selectively modulate SHIP activity and which offer novel opportunities to manipulate PI3K mediated signaling in the immune system.
Collapse
Affiliation(s)
- Matthew D Blunt
- Inflammatory Cell Biology Laboratory, Department of Pharmacy and Pharmacology, University of Bath Bath, UK
| | | |
Collapse
|
34
|
So EYW, Mui ALF. A new paradigm in phosphoinositide signaling? (Comment on DOI 10.1002/bies.201100195). Bioessays 2012; 34:633. [PMID: 22791387 DOI: 10.1002/bies.201200091] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Eva Y W So
- Immunity and Infection Research Centre, Vancouver Coastal Health Research Institute and Department of Surgery, University of British Columbia, Vancouver, Canada
| | | |
Collapse
|
35
|
Edimo WE, Janssens V, Waelkens E, Erneux C. Reversible Ser/Thr SHIP phosphorylation: a new paradigm in phosphoinositide signalling?: Targeting of SHIP1/2 phosphatases may be controlled by phosphorylation on Ser and Thr residues. Bioessays 2012; 34:634-42. [PMID: 22641604 DOI: 10.1002/bies.201100195] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Phosphoinositide (PI) phosphatases such as the SH2 domain-containing inositol 5-phosphatases 1/2 (SHIP1 and 2) are important signalling enzymes in human physiopathology. SHIP1/2 interact with a large number of immune and growth factor receptors. Tyrosine phosphorylation of SHIP1/2 has been considered to be the determining regulatory modification. However, here we present a hypothesis, based on recent key publications, highlighting the determining role of Ser/Thr phosphorylation in regulating several key properties of SHIP1/2. Since a subunit of the Ser/Thr phosphatase PP2A has been shown to interact with SHIP2, a putative mechanism for reversing SHIP2 Ser/Thr phosphorylation can be anticipated. PI phosphatases are potential target molecules in human diseases, particularly, but not exclusively, in cancer and diabetes. Therefore, this novel regulatory mechanism deserves further attention in the hunt for discovering novel or complementary therapeutic strategies. This mechanism may be more broadly involved in regulating PI signalling in the case of synaptojanin1 or the phosphatase, tensin homolog, deleted on chromosome TEN.
Collapse
Affiliation(s)
- William's Elong Edimo
- Institut de Recherche Interdisciplinaire (IRIBHM), Université Libre de Bruxelles, Campus Erasme, Brussels, Belgium
| | | | | | | |
Collapse
|
36
|
Peluffo MC, Ting AY, Zamah AM, Conti M, Stouffer RL, Zelinski MB, Hennebold JD. Amphiregulin promotes the maturation of oocytes isolated from the small antral follicles of the rhesus macaque. Hum Reprod 2012; 27:2430-7. [PMID: 22593432 DOI: 10.1093/humrep/des158] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND In non-primates, the epidermal growth factor (EGF) and EGF-related ligands such as amphiregulin (AREG) serve as critical intermediates between the theca/mural cells and the cumulus-oocyte-complex (COC) following the mid-cycle LH surge. Studies were designed in primates (1) to analyze AREG levels in follicular fluid (follicular fluid) obtained from pre-ovulatory follicles, as well as (2) to assess dose-dependent effects of AREG on oocytes from small antral follicles (SAFs) during culture, including meiotic and cytoplasmic maturation. METHODS Controlled ovulation protocols were performed on rhesus monkeys (n=12) to determine AREG content within the single, naturally selected dominant follicle after an ovulatory stimulus. Using healthy COCs (n=271) obtained from SAFs during spontaneous cycles (n=27), in vitro maturation (IVM) was performed in the absence or presence of physiological concentrations of AREG (10 or 100 ng/ml) with or without gonadotrophins (FSH, 75 mIU/ml; LH, 75 mIU/ml). At the end of the culture period, oocyte meiotic maturation was evaluated and ICSI was performed (n=111), from which fertilization and early embryo development was followed in vitro. RESULTS AREG levels in follicular fluid from pre-ovulatory follicles increased (P<0.05) following an ovulatory bolus of hCG at 12, 24 and 36 h post-treatment. At 12 h post-hCG, AREG levels in follicular fluid ranged from 4.8 to 121.4 ng/ml. Rhesus macaque COCs incubated with 10 ng/ml AREG in the presence of gonadotrophins displayed an increased percentage of oocytes that progressed to the metaphase II (MII) stage of meiosis (82 versus 56%, P<0.05) and a decreased percentage of metaphase I (MI) oocytes (2 versus 23%, P<0.05) relative to controls, respectively. The percentage of either MI or MII oocytes at the end of the culture period was not different between oocytes cultured with 100 ng/ml AREG or in media alone. Fertilization and first cleavage rates obtained by ICSI of all IVM MII oocytes were 93 and 98%, respectively, and did not vary among treatment groups. Of the MII oocytes that fertilized (n=103), 37 were randomly selected and maintained in culture to assess developmental potential. A total of 13 early blastocysts were obtained, with four embryos developing to expanded blastocysts. CONCLUSIONS These data indicate that AREG levels increase in rhesus macaque pre-ovulatory follicles after an ovulatory stimulus, and a specific concentration of AREG (10 ng/ml) enhances rhesus macaque oocyte nuclear maturation but not cytoplasmic maturation from SAFs obtained during the natural menstrual cycle. However, owing to the small number of samples in some treatment groups, further studies are now required.
Collapse
Affiliation(s)
- Marina C Peluffo
- Centro de Investigaciones Endocrinológicas (CEDIE-CONICET), Hospital de Niños Ricardo Gutierrez, Gallo 1330, C1425SEFD Ciudad Autónoma de Buenos Aires, Argentina
| | | | | | | | | | | | | |
Collapse
|
37
|
Sents W, Ivanova E, Lambrecht C, Haesen D, Janssens V. The biogenesis of active protein phosphatase 2A holoenzymes: a tightly regulated process creating phosphatase specificity. FEBS J 2012; 280:644-61. [PMID: 22443683 DOI: 10.1111/j.1742-4658.2012.08579.x] [Citation(s) in RCA: 157] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Protein phosphatase type 2A (PP2A) enzymes constitute a large family of Ser/Thr phosphatases with multiple functions in cellular signaling and physiology. The composition of heterotrimeric PP2A holoenzymes, resulting from the combinatorial assembly of a catalytic C subunit, a structural A subunit, and regulatory B-type subunit, provides the essential determinants for substrate specificity, subcellular targeting, and fine-tuning of phosphatase activity, largely explaining why PP2A is functionally involved in so many diverse physiological processes, sometimes in seemingly opposing ways. In this review, we highlight how PP2A holoenzyme biogenesis and enzymatic activity are controlled by a sophisticatedly coordinated network of five PP2A modulators, consisting of α4, phosphatase 2A phosphatase activator (PTPA), leucine carboxyl methyl transferase 1 (LCMT1), PP2A methyl esterase 1 (PME-1) and, potentially, target of rapamycin signaling pathway regulator-like 1 (TIPRL1), which serve to prevent promiscuous phosphatase activity until the holoenzyme is completely assembled. Likewise, these modulators may come into play when PP2A holoenzymes are disassembled following particular cellular stresses. Malfunctioning of these cellular control mechanisms contributes to human disease. The potential therapeutic benefits or pitfalls of interfering with these regulatory mechanisms will be briefly discussed.
Collapse
Affiliation(s)
- Ward Sents
- Laboratory of Protein Phosphorylation & Proteomics, Department of Cellular and Molecular Medicine, University of Leuven, Leuven, Belgium
| | | | | | | | | |
Collapse
|
38
|
Erneux C, Edimo WE, Deneubourg L, Pirson I. SHIP2 multiple functions: a balance between a negative control of PtdIns(3,4,5)P₃ level, a positive control of PtdIns(3,4)P₂ production, and intrinsic docking properties. J Cell Biochem 2011; 112:2203-9. [PMID: 21503961 DOI: 10.1002/jcb.23146] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The SH2 domain containing inositol 5-phosphatase 2 (SHIP2) belongs to the family of the mammalian inositol polyphosphate 5-phosphatases. The two closely related isoenzymes SHIP1 (or SHIP) and SHIP2 contain a N-terminal SH2 domain, a catalytic domain, potential PTB domain-binding sites (NPXY), and C-terminal proline-rich regions with consensus sites for SH3 domain interactions. In addition, SHIP2 contains a unique sterile alpha motif (SAM) domain that could be involved in SAM-SAM domain interactions with other proteins or receptors. SHIP2 also shows the presence of an ubiquitin interacting motif at the C-terminal end. SHIP2 is essentially a PI(3,4,5)P(3) 5-phosphatase that negatively controls PI(3,4,5)P(3) levels in intact cells and produce PI(3,4)P(2) . Depending on the cells and stimuli, PI(3,4)P(2) could accumulate at important levels and be a "second messenger" by its own. It could interact with a very large number of target proteins such as PKB or TAPP1 and 2 that control insulin sensitivity. In addition to its catalytic activity, SHIP2 is also a docking protein for a large number of proteins: Cytoskeletal, focal adhesion proteins, scaffold proteins, adaptors, protein phosphatases, and tyrosine kinase associated receptors. These interactions could play a role in the control of cell adhesion, migration, or endocytosis of some receptors. SHIP2 could be acting independently of its phosphatase activity being part of a protein network of some receptors, e.g., the EGF receptor or BCR/ABL. These non-catalytic properties associated to a PI phosphatase have also been reported for other enzymes of the metabolism of myo-inositol such as Ins(1,4,5)P(3) 3-kinases, inositol phosphate multikinase (IPMK), or PTEN.
Collapse
Affiliation(s)
- Christophe Erneux
- Institut de Recherche Interdisciplinaire (IRIBHM), Université Libre de Bruxelles, Campus Erasme, Bldg. C, 808 Route de Lennik, 1070 Brussels, Belgium.
| | | | | | | |
Collapse
|
39
|
Evidence of SHIP2 Ser132 phosphorylation, its nuclear localization and stability. Biochem J 2011; 439:391-401. [DOI: 10.1042/bj20110173] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
PtdIns(3,4,5)P3 and PtdIns(3,4)P2 are major signalling molecules in mammalian cell biology. PtdIns(3,4)P2 can be produced by PI3Ks [PI (phosphoinositide) 3-kinases], but also by PI 5-phosphatases including SHIP2 [SH2 (Src homology 2)-domain-containing inositol phosphatase 2]. Proteomic studies in human cells revealed that SHIP2 can be phosphorylated at more than 20 sites, but their individual function is unknown. In a model of PTEN (phosphatase and tensin homologue deleted on chromosome 10)-null astrocytoma cells, lowering SHIP2 expression leads to increased PtdIns(3,4,5)P3 levels and Akt phosphorylation. MS analysis identified SHIP2 phosphosites on Ser132, Thr1254 and Ser1258; phosphotyrosine-containing sites were undetectable. By immunostaining, total SHIP2 concentrated in the perinuclear area and in the nucleus, whereas SHIP2 phosphorylated on Ser132 was in the cytoplasm, the nucleus and nuclear speckles, depending on the cell cycle stage. SHIP2 phosphorylated on Ser132 demonstrated PtdIns(4,5)P2 phosphatase activity. Endogenous phospho-SHIP2 (Ser132) showed an overlap with PtdIns(4,5)P2 staining in nuclear speckles. SHIP2 S132A was less sensitive to C-terminal degradation and more resistant to calpain as compared with wild-type enzyme. We have identified nuclear lamin A/C as a novel SHIP2 interactor. We suggest that the function of SHIP2 is different at the plasma membrane where it recognizes PtdIns(3,4,5)P3, and in the nucleus where it may interact with PtdIns(4,5)P2, particularly in speckles.
Collapse
|
40
|
Slupe AM, Merrill RA, Strack S. Determinants for Substrate Specificity of Protein Phosphatase 2A. Enzyme Res 2011; 2011:398751. [PMID: 21755039 PMCID: PMC3132988 DOI: 10.4061/2011/398751] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Accepted: 04/28/2011] [Indexed: 12/22/2022] Open
Abstract
Protein phosphatase 2A- (PP2A-) catalyzed dephosphorylation of target substrate proteins is widespread and critical for cellular function. PP2A is predominantly found as a heterotrimeric complex of a catalytic subunit (C), a scaffolding subunit (A), and one member of 4 families of regulatory subunits (B). Substrate specificity of the holoenzyme complex is determined by the subcellular locale the complex is confined to, selective incorporation of the B subunit, interactions with endogenous inhibitory proteins, and specific intermolecular interactions between PP2A and target substrates. Here, we discuss recent studies that have advanced our understanding of the molecular determinants for PP2A substrate specificity.
Collapse
Affiliation(s)
- Andrew M Slupe
- Department of Pharmacology, University of Iowa, 2-432 BSB, Iowa City, IA 52242, USA
| | | | | |
Collapse
|
41
|
Sablina AA, Hector M, Colpaert N, Hahn WC. Identification of PP2A complexes and pathways involved in cell transformation. Cancer Res 2011; 70:10474-84. [PMID: 21159657 DOI: 10.1158/0008-5472.can-10-2855] [Citation(s) in RCA: 132] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The simian virus 40 small t (SV40ST) oncoprotein interacts with protein phosphatase 2A (PP2A), an abundantly expressed family of serine-threonine phosphatases. This interaction is essential for the transformation of human cells by SV40, and several PP2A subunits have been implicated as tumor suppressor genes. However, the pathways controlled by specific PP2A complexes involved in cell transformation remain incompletely understood. Using a comprehensive loss-of-function approach, we identified 4 PP2A regulatory subunits [B56α, B56γ, PR72/PR130, and PTPA (protein phosphatase 2A activator)], which when suppressed replaced the expression of SV40ST in human cell transformation. We found that manipulation of complexes containing PP2A B56α, B56γ, and PR72/PR130 activates the pathways regulated by c-Myc, Wnt, and PI3K (phosphoinositide 3-kinase)/Akt in a manner that depends on their specific phosphatase activity. In contrast, suppression of PTPA disrupts the assembly of PP2A heterotrimeric complexes, which leads to the activation of these same oncogenic pathways. These observations delineate the PP2A family members and pathways perturbed by SV40ST during human cell transformation.
Collapse
Affiliation(s)
- Anna A Sablina
- Department of Medical Oncology, Dana-Farber Cancer Institute, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA.
| | | | | | | |
Collapse
|