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Kulkarni P, Salgia R, Rangarajan G. Intrinsically disordered proteins and conformational noise: The hypothesis a decade later. iScience 2023; 26:107109. [PMID: 37408690 PMCID: PMC10319216 DOI: 10.1016/j.isci.2023.107109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/07/2023] Open
Abstract
Phenotypic plasticity is the ability of individual genotypes to produce different phenotypes in response to environmental perturbations. We previously postulated how conformational noise emanating from conformational dynamics of intrinsically disordered proteins (IDPs) which is distinct from transcriptional noise, can contribute to phenotypic switching by rewiring the cellular protein interaction network. Since most transcription factors are IDPs, we posited that conformational noise is an integral component of transcriptional noise implying that IDPs may amplify total noise in the system either stochastically or in response to environmental changes. Here, we review progress in elucidating the details of the hypothesis. We highlight empirical evidence supporting the hypothesis, discuss conceptual advances that underscore its fundamental importance and implications, and identify areas for future investigations.
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Affiliation(s)
- Prakash Kulkarni
- Department of Medical Oncology and Therapeutics Research, City of Hope National Medical Center, Duarte, CA, USA
- Department of Systems Biology, City of Hope National Medical Center, Duarte, CA, USA
| | - Ravi Salgia
- Department of Medical Oncology and Therapeutics Research, City of Hope National Medical Center, Duarte, CA, USA
| | - Govindan Rangarajan
- Department of Mathematics, Indian Institute of Science, Bangalore 560012, India
- Center for Neuroscience, Indian Institute of Science, Bangalore 560012, India
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Illuminating Intrinsically Disordered Proteins with Integrative Structural Biology. Biomolecules 2023; 13:biom13010124. [PMID: 36671509 PMCID: PMC9856150 DOI: 10.3390/biom13010124] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 01/01/2023] [Accepted: 01/04/2023] [Indexed: 01/11/2023] Open
Abstract
Intense study of intrinsically disordered proteins (IDPs) did not begin in earnest until the late 1990s when a few groups, working independently, convinced the community that these 'weird' proteins could have important functions. Over the past two decades, it has become clear that IDPs play critical roles in a multitude of biological phenomena with prominent examples including coordination in signaling hubs, enabling gene regulation, and regulating ion channels, just to name a few. One contributing factor that delayed appreciation of IDP functional significance is the experimental difficulty in characterizing their dynamic conformations. The combined application of multiple methods, termed integrative structural biology, has emerged as an essential approach to understanding IDP phenomena. Here, we review some of the recent applications of the integrative structural biology philosophy to study IDPs.
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The Prostate-Associated Gene 4 (PAGE4) Could Play a Role in the Development of Benign Prostatic Hyperplasia under Oxidative Stress. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2022; 2022:7041739. [PMID: 35633887 PMCID: PMC9135540 DOI: 10.1155/2022/7041739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Revised: 04/19/2022] [Accepted: 05/05/2022] [Indexed: 11/18/2022]
Abstract
Benign prostatic hyperplasia (BPH) is a common disease in elderly men with uncertain molecular mechanism, and oxidative stress (OS) has also been found associated with BPH development. Recently, we found that prostate-associated gene 4 (PAGE4) was one of the most significantly changed differentially expressed genes (DEGs) in BPH, which can protect cells against stress stimulation. However, the exact role of PAGE4 in BPH remains unclear. This study is aimed at exploring the effect of PAGE4 in BPH under OS. Human prostate tissues and cultured WPMY-1 and PrPF cells were utilized. The expression and localization of PAGE4 were determined with qRT-PCR, Western blotting, and immunofluorescence staining. OS cell models induced with H2O2 were treated with PAGE4 silencing or PAGE4 overexpression or inhibitor (N-acetyl-L-cysteine (NAC)) of OS. The proliferation activity, apoptosis, OS markers, and MAPK signaling pathways were detected by CCK-8 assay, flow cytometry analysis, and Western blotting. PAGE4 was shown to be upregulated in human hyperplastic prostate and mainly located in the stroma. Acute OS induced with H2O2 increased PAGE4 expression (which was prevented by OS inhibitor), apoptosis, cell cycle arrest, and reactive oxygen species (ROS) accumulation in WPMY-1 and PrPF cells. siPAGE4 plus H2O2 potentiated H2O2 effect via reducing the p-ERK1/2 level and increasing p-JNK1/2 level. Consistently, overexpression of PAGE4 offset the effect of H2O2 and partially reversed the PAGE4 silencing effect. However, knocking down and overexpression of PAGE4 alone determined no significant effects. Our novel data demonstrated that augmented PAGE4 promotes cell survival by activating p-ERK1/2 and decreases cell apoptosis by inhibiting p-JNK1/2 under the OS, which could contribute to the development of BPH.
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Protein conformational dynamics and phenotypic switching. Biophys Rev 2021; 13:1127-1138. [PMID: 35059032 PMCID: PMC8724335 DOI: 10.1007/s12551-021-00858-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 10/18/2021] [Indexed: 12/14/2022] Open
Abstract
Intrinsically disordered proteins (IDPs) are proteins that lack rigid 3D structure but exist as conformational ensembles. Because of their structural plasticity, they can interact with multiple partners. The protein interactions between IDPs and their partners form scale-free protein interaction networks (PINs) that facilitate information flow in the cell. Because of their plasticity, IDPs typically occupy hub positions in cellular PINs. Furthermore, their conformational dynamics and propensity for post-translational modifications contribute to "conformational" noise which is distinct from the well-recognized transcriptional noise. Therefore, upregulation of IDPs in response to a specific input, such as stress, contributes to increased noise and, hence, an increase in stochastic, "promiscuous" interactions. These interactions lead to activation of latent pathways or can induce "rewiring" of the PIN to yield an optimal output underscoring the critical role of IDPs in regulating information flow. We have used PAGE4, a highly intrinsically disordered stress-response protein as a paradigm. Employing a variety of experimental and computational techniques, we have elucidated the role of PAGE4 in phenotypic switching of prostate cancer cells at a systems level. These cumulative studies over the past decade provide a conceptual framework to better understand how IDP conformational dynamics and conformational noise might facilitate cellular decision-making.
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Fatafta H, Kav B, Bundschuh BF, Loschwitz J, Strodel B. Disorder-to-order transition of the amyloid-β peptide upon lipid binding. Biophys Chem 2021; 280:106700. [PMID: 34784548 DOI: 10.1016/j.bpc.2021.106700] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Accepted: 10/15/2021] [Indexed: 12/18/2022]
Abstract
There is mounting evidence that Alzheimer's disease progression and severity are linked to neuronal membrane damage caused by aggregates of the amyloid-β (Aβ) peptide. However, the detailed mechanism behind the membrane damage is not well understood yet. Recently, the lipid-chaperone hypothesis has been put forward, based on which the formation of complexes between Aβ and free lipids enables an easy insertion of Aβ into membranes. In order to test this hypothesis, we performed numerous all-atom molecular dynamics simulations. We studied the complex formation between individual lipids, considering both POPC and DPPC, and Aβ and examined whether the resulting complexes would be able to insert into lipid membranes. Complex formation at a one-to-one ratio was readily observed, yet with minimal effects on Aβ's characteristics. Most importantly, the peptide remains largely disordered in 1:1 complexes, and the complex does not insert into the membrane; instead, it is adsorbed to the membrane surface. The results change considerably once Aβ forms a complex with a POPC cluster composed of three lipid molecules. The hydrophobic interactions between Aβ and the lipid tails cause the peptide to fold into either a helical or a β-sheet structure. These observations provide atomic insight into the disorder-to-order transition that is needed for membrane insertion or amyloid aggregation to proceed.
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Affiliation(s)
- Hebah Fatafta
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Batuhan Kav
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Bastian F Bundschuh
- Institute of Theoretical and Computational Chemistry, Heinrich Heine University Düsseldorf, Universitütstrasse 1, 40225 Düsseldorf, Germany
| | - Jennifer Loschwitz
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, 52425 Jülich, Germany; Institute of Theoretical and Computational Chemistry, Heinrich Heine University Düsseldorf, Universitütstrasse 1, 40225 Düsseldorf, Germany
| | - Birgit Strodel
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, 52425 Jülich, Germany; Institute of Theoretical and Computational Chemistry, Heinrich Heine University Düsseldorf, Universitütstrasse 1, 40225 Düsseldorf, Germany.
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Oliveira Junior AB, Lin X, Kulkarni P, Onuchic JN, Roy S, Leite VBP. Exploring Energy Landscapes of Intrinsically Disordered Proteins: Insights into Functional Mechanisms. J Chem Theory Comput 2021; 17:3178-3187. [PMID: 33871257 DOI: 10.1021/acs.jctc.1c00027] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Intrinsically disordered proteins (IDPs) lack a rigid three-dimensional structure and populate a polymorphic ensemble of conformations. Because of the lack of a reference conformation, their energy landscape representation in terms of reaction coordinates presents a daunting challenge. Here, our newly developed energy landscape visualization method (ELViM), a reaction coordinate-free approach, shows its prime application to explore frustrated energy landscapes of an intrinsically disordered protein, prostate-associated gene 4 (PAGE4). PAGE4 is a transcriptional coactivator that potentiates the oncogene c-Jun. Two kinases, namely, HIPK1 and CLK2, phosphorylate PAGE4, generating variants phosphorylated at different serine/threonine residues (HIPK1-PAGE4 and CLK2-PAGE4, respectively) with opposing functions. While HIPK1-PAGE4 predominantly phosphorylates Thr51 and potentiates c-Jun, CLK2-PAGE4 hyperphosphorylates PAGE4 and attenuates transactivation. To understand the underlying mechanisms of conformational diversity among different phosphoforms, we have analyzed their atomistic trajectories simulated using AWSEM forcefield, and the energy landscapes were elucidated using ELViM. This method allows us to identify and compare the population distributions of different conformational ensembles of PAGE4 phosphoforms using the same effective phase space. The results reveal a predominant conformational ensemble with an extended C-terminal segment of WT PAGE4, which exposes a functional residue Thr51, implying its potential of undertaking a fly-casting mechanism while binding to its cognate partner. In contrast, for HIPK1-PAGE4, a compact conformational ensemble enhances its population sequestering phosphorylated-Thr51. This clearly explains the experimentally observed weaker affinity of HIPK1-PAGE4 for c-Jun. ELViM appears as a powerful tool, especially to analyze the highly frustrated energy landscape representation of IDPs where appropriate reaction coordinates are hard to apprehend.
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Affiliation(s)
- Antonio B Oliveira Junior
- Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005-1892, United States
| | - Xingcheng Lin
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, United States
| | - Prakash Kulkarni
- Department of Medical Oncology and Therapeutics Research, City of Hope National Medical Center, Duarte, California 91010, United States
| | - José N Onuchic
- Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005-1892, United States
| | - Susmita Roy
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, West Bengal 741246, India
| | - Vitor B P Leite
- Departamento de Física, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista (UNESP), São José do Rio Preto, São Paulo 15054-000, Brazil
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Fatafta H, Samantray S, Sayyed-Ahmad A, Coskuner-Weber O, Strodel B. Molecular simulations of IDPs: From ensemble generation to IDP interactions leading to disorder-to-order transitions. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2021; 183:135-185. [PMID: 34656328 DOI: 10.1016/bs.pmbts.2021.06.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/26/2023]
Abstract
Intrinsically disordered proteins (IDPs) lack a well-defined three-dimensional structure but do exhibit some dynamical and structural ordering. The structural plasticity of IDPs indicates that entropy-driven motions are crucial for their function. Many IDPs undergo function-related disorder-to-order transitions upon by their interaction with specific binding partners. Approaches that are based on both experimental and theoretical tools enable the biophysical characterization of IDPs. Molecular simulations provide insights into IDP structural ensembles and disorder-to-order transition mechanisms. However, such studies depend strongly on the chosen force field parameters and simulation techniques. In this chapter, we provide an overview of IDP characteristics, review all-atom force fields recently developed for IDPs, and present molecular dynamics-based simulation methods that allow IDP ensemble generation as well as the characterization of disorder-to-order transitions. In particular, we introduce metadynamics, replica exchange molecular dynamics simulations, and also kinetic models resulting from Markov State modeling, and provide various examples for the successful application of these simulation methods to IDPs.
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Affiliation(s)
- Hebah Fatafta
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany
| | - Suman Samantray
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany; AICES Graduate School, RWTH Aachen University, Aachen, Germany
| | | | - Orkid Coskuner-Weber
- Molecular Biotechnology, Turkish-German University, Sahinkaya Caddesi, Istanbul, Turkey
| | - Birgit Strodel
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany; Institute of Theoretical and Computational Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.
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Kulkarni P. Intrinsically Disordered Proteins: Insights from Poincaré, Waddington, and Lamarck. Biomolecules 2020; 10:biom10111490. [PMID: 33126482 PMCID: PMC7692701 DOI: 10.3390/biom10111490] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Accepted: 10/12/2020] [Indexed: 12/28/2022] Open
Abstract
The past quarter-century may justly be referred to as a period analogous to the “Cambrian explosion” in the history of proteins. This period is marked by the appearance of the intrinsically disordered proteins (IDPs) on the scene since their discovery in the mid-1990s. Here, I first reflect on how we accidentally stumbled on these fascinating molecules. Next, I describe our research on the IDPs over the past decade and identify six areas as important for future research in this field. In addition, I draw on discoveries others in the field have made to present a more comprehensive essay. More specifically, I discuss the role of IDPs in two fundamental aspects of life: in phenotypic switching, and in multicellularity that marks one of the major evolutionary transitions. I highlight how serendipity, imagination, and an interdisciplinary approach embodying empirical evidence and theoretical insights from the works of Poincaré, Waddington, and Lamarck, shaped our thinking, and how this led us to propose the MRK hypothesis, a conceptual framework addressing phenotypic switching, the emergence of new traits, and adaptive evolution via nongenetic and IDP conformation-based mechanisms. Finally, I present a perspective on the evolutionary link between phenotypic switching and the origin of multicellularity.
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Affiliation(s)
- Prakash Kulkarni
- Department of Medical Oncology and Experimental Therapeutics, City of Hope, National Medical Center, Duarte, CA 91010, USA
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Fu S, Liu T, Lv C, Fu C, Zeng R, Kakehi Y, Kulkarni P, Getzenberg RH, Zeng Y. Stromal-epithelial interactions in prostate cancer: Overexpression of PAGE4 in stromal cells inhibits the invasive ability of epithelial cells. J Cell Biochem 2020; 121:4406-4418. [PMID: 32003504 DOI: 10.1002/jcb.29664] [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: 10/20/2019] [Accepted: 01/09/2020] [Indexed: 12/17/2022]
Abstract
It is now widely recognized that carcinoma-associated fibroblasts which are believed to be myofibroblasts, promote the transformation of prostate epithelial cells to cancer cells, enhance their proliferation and invasiveness, and induce the acquisition of resistance to cancer therapy and immune evasiveness. Prostate-associated gene 4 (PAGE4) is an intrinsically disordered protein that is remarkably prostate-specific. PAGE4 is also a stress-response protein that functions as a transcriptional regulator and is upregulated in early-stage prostate cancer (PCa) and its precursor lesions. However, PAGE4 is downregulated in high-grade PCa and metastatic disease. Here, we show that PAGE4 is highly expressed in the stromal cells surrounding the cancer-adjacent "normal" glands and low-grade PCa lesions but not in lesions proximal to high-grade PCa. Overexpression of PAGE4 in a stromal cell line inhibits the migration and invasion of PCa epithelial cells in multiple coculture systems. PAGE4 overexpression also inhibits the downregulation of E-cadherin in PCa epithelial cells when cocultured with stromal cells. Furthermore, signaling via tumor necrosis factor-α and transforming growth factor-β pathways is decreased in the stromal cells overexpressing PAGE4 suggesting that PAGE4 appears to play a protective role against disease progression by perturbing interactions between epithelial cells and stromal cells in PCa. Taken together, these findings support previous observations that upregulation of PAGE4 in PCa correlates with a better prognosis and highlight PAGE4 as a novel therapeutic target for early-stage "low-risk" disease.
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Affiliation(s)
- Shui Fu
- Department of Urology, Liaoning Cancer Hospital and Institute, Cancer Hospital of China Medical University, Shenyang, Liaoning, China
| | - Tao Liu
- Department of Urology, The First Hospital of China Medical University, Shenyang, Liaoning, China
| | - Chengcheng Lv
- Department of Urology, Liaoning Cancer Hospital and Institute, Cancer Hospital of China Medical University, Shenyang, Liaoning, China
| | - Cheng Fu
- Department of Urology, Liaoning Cancer Hospital and Institute, Cancer Hospital of China Medical University, Shenyang, Liaoning, China
| | - Ruoheng Zeng
- Department of Neuroscience, College of Art and Science, New York University, New York, New York
| | - Yoshiyuki Kakehi
- Department of Urology, Kagawa University Faculty of Medicine, Kagawa, Kita-gun, Japan
| | - Prakash Kulkarni
- Department of Medical Oncology and Therapeutics Research, City of Hope National Medical Center, Duarte, California
| | - Robert H Getzenberg
- Research Division, College of Allopathic Medicine, Nova Southeastern University, Fort Lauderdale, Florida
| | - Yu Zeng
- Department of Urology, Liaoning Cancer Hospital and Institute, Cancer Hospital of China Medical University, Shenyang, Liaoning, China
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Kulkarni V, Kulkarni P. Intrinsically disordered proteins and phenotypic switching: Implications in cancer. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2019; 166:63-84. [PMID: 31521237 DOI: 10.1016/bs.pmbts.2019.03.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
It is now well established that intrinsically disordered proteins (IDPs) that constitute a large part of the proteome across the three kingdoms, play critical roles in several biological processes including phenotypic switching. However, dysregulated expression of IDPs that engage in promiscuous interactions can lead to pathological states. In this chapter, using cancer as a paradigm, we discuss how IDP conformational dynamics and the resultant conformational noise can modulate phenotypic switching. Thus, contrary to the prevailing wisdom that phenotypic switching is highly deterministic (has a genetic underpinning) in cancer, emerging evidence suggests that non-genetic mechanisms, at least in part due to the conformational noise, may also be a confounding factor in phenotypic switching.
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Affiliation(s)
- Vivek Kulkarni
- Division of Biology & Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Prakash Kulkarni
- Department of Medical Oncology and Therapeutics Research, City of Hope National Medical Center, Duarte, CA, United States.
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Choi UB, Sanabria H, Smirnova T, Bowen ME, Weninger KR. Spontaneous Switching among Conformational Ensembles in Intrinsically Disordered Proteins. Biomolecules 2019; 9:biom9030114. [PMID: 30909517 PMCID: PMC6468417 DOI: 10.3390/biom9030114] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 03/14/2019] [Accepted: 03/15/2019] [Indexed: 01/08/2023] Open
Abstract
The common conception of intrinsically disordered proteins (IDPs) is that they stochastically sample all possible configurations driven by thermal fluctuations. This is certainly true for many IDPs, which behave as swollen random coils that can be described using polymer models developed for homopolymers. However, the variability in interaction energy between different amino acid sequences provides the possibility that some configurations may be strongly preferred while others are forbidden. In compact globular IDPs, core hydration and packing density can vary between segments of the polypeptide chain leading to complex conformational dynamics. Here, we describe a growing number of proteins that appear intrinsically disordered by biochemical and bioinformatic characterization but switch between restricted regions of conformational space. In some cases, spontaneous switching between conformational ensembles was directly observed, but few methods can identify when an IDP is acting as a restricted chain. Such switching between disparate corners of conformational space could bias ligand binding and regulate the volume of IDPs acting as structural or entropic elements. Thus, mapping the accessible energy landscape and capturing dynamics across a wide range of timescales are essential to recognize when an IDP is acting as such a switch.
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Affiliation(s)
- Ucheor B Choi
- Department of Molecular and Cellular Physiology, Department of Neurology and Neurological Sciences, Department of Structural Biology, Department of Photon Science, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA.
| | - Hugo Sanabria
- Department of Physics and Astronomy, Clemson University, Clemson, SC, 29634, USA.
| | - Tatyana Smirnova
- Department of Chemistry, North Carolina State University, Raleigh, NC, 27695, USA.
| | - Mark E Bowen
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY, 11794, USA.
| | - Keith R Weninger
- Department of Physics, North Carolina State University, Raleigh, NC, 27695, USA.
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Structural and Dynamical Order of a Disordered Protein: Molecular Insights into Conformational Switching of PAGE4 at the Systems Level. Biomolecules 2019; 9:biom9020077. [PMID: 30813315 PMCID: PMC6406393 DOI: 10.3390/biom9020077] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 02/10/2019] [Accepted: 02/10/2019] [Indexed: 01/10/2023] Open
Abstract
Folded proteins show a high degree of structural order and undergo (fairly constrained) collective motions related to their functions. On the other hand, intrinsically disordered proteins (IDPs), while lacking a well-defined three-dimensional structure, do exhibit some structural and dynamical ordering, but are less constrained in their motions than folded proteins. The larger structural plasticity of IDPs emphasizes the importance of entropically driven motions. Many IDPs undergo function-related disorder-to-order transitions driven by their interaction with specific binding partners. As experimental techniques become more sensitive and become better integrated with computational simulations, we are beginning to see how the modest structural ordering and large amplitude collective motions of IDPs endow them with an ability to mediate multiple interactions with different partners in the cell. To illustrate these points, here, we use Prostate-associated gene 4 (PAGE4), an IDP implicated in prostate cancer (PCa) as an example. We first review our previous efforts using molecular dynamics simulations based on atomistic AWSEM to study the conformational dynamics of PAGE4 and how its motions change in its different physiologically relevant phosphorylated forms. Our simulations quantitatively reproduced experimental observations and revealed how structural and dynamical ordering are encoded in the sequence of PAGE4 and can be modulated by different extents of phosphorylation by the kinases HIPK1 and CLK2. This ordering is reflected in changing populations of certain secondary structural elements as well as in the regularity of its collective motions. These ordered features are directly correlated with the functional interactions of WT-PAGE4, HIPK1-PAGE4 and CLK2-PAGE4 with the AP-1 signaling axis. These interactions give rise to repeated transitions between (high HIPK1-PAGE4, low CLK2-PAGE4) and (low HIPK1-PAGE4, high CLK2-PAGE4) cell phenotypes, which possess differing sensitivities to the standard PCa therapies, such as androgen deprivation therapy (ADT). We argue that, although the structural plasticity of an IDP is important in promoting promiscuous interactions, the modulation of the structural ordering is important for sculpting its interactions so as to rewire with agility biomolecular interaction networks with significant functional consequences.
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Lv C, Fu S, Dong Q, Yu Z, Zhang G, Kong C, Fu C, Zeng Y. PAGE4 promotes prostate cancer cells survive under oxidative stress through modulating MAPK/JNK/ERK pathway. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2019; 38:24. [PMID: 30658679 PMCID: PMC6339303 DOI: 10.1186/s13046-019-1032-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Accepted: 01/09/2019] [Indexed: 02/08/2023]
Abstract
Background Prostate cancer (PCa) is one of the most common cancers in male worldwide. Oxidative stress has been recognized as one of the driving signals pathologically linked to PCa progression. Nevertheless, the association of oxidative stress with PCa progression remains unclear. Methods Western blot, q-RT-PCR and bioinformatics analyses were used to examine PAGE4 expression. Comet assay and Annexin V/ PI dual staining assay were performed to investigate DNA damage and cell death under oxidative stress. Mouse xenograft model of PCa cells was established to verify the role of PAGE4 in vivo. Transcriptomic analysis was performed to investigate the underlying mechanism for the function of PAGE4 under oxidative stress. Western blot assay was conducted to determine the status of MAPK pathway. Immunohistochemistry was used to identify protein expression of PAGE4 in tumor tissues. Results In this study, we found that PAGE4 expression was increased in PCa cells under oxidative stress condition. PAGE4 overexpression protected PCa cells from oxidative stress-inducing cell death by reducing DNA damage. PAGE4 overexpression promoted PCa cells growth in vivo. Mechanistically, PAGE4 promoted the survival of prostate cancer cells through regulating MAPK pathway which reflected in decreasing the phosphorylation of MAP2K4, JNK and c-JUN but increasing phosphorylation of ERK1/2. Conclusion Our findings indicate that PAGE4 protects PCa cells from DNA damage and apoptosis under oxidative stress by modulating MAPK signalling pathway. PAGE4 expression may serve as a prognostic biomarker for clinical applications. Electronic supplementary material The online version of this article (10.1186/s13046-019-1032-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Chengcheng Lv
- Department of Urology, Cancer Hospital of China Medical University, Liaoning Cancer Hospital and Institute, 44 Xiaoheyan Road, Shenyang, 110042, Liaoning, China
| | - Shui Fu
- Department of Urology, Cancer Hospital of China Medical University, Liaoning Cancer Hospital and Institute, 44 Xiaoheyan Road, Shenyang, 110042, Liaoning, China
| | - Qingzhuo Dong
- Department of Urology, The First Hospital of China Medical University, 155 Nanjing North Road, Shenyang, 110001, Liaoning, China
| | - Zi Yu
- Department of Urology, The First Hospital of China Medical University, 155 Nanjing North Road, Shenyang, 110001, Liaoning, China
| | - Gejun Zhang
- Department of Urology, The First Hospital of China Medical University, 155 Nanjing North Road, Shenyang, 110001, Liaoning, China
| | - Chuize Kong
- Department of Urology, The First Hospital of China Medical University, 155 Nanjing North Road, Shenyang, 110001, Liaoning, China
| | - Cheng Fu
- Department of Urology, Cancer Hospital of China Medical University, Liaoning Cancer Hospital and Institute, 44 Xiaoheyan Road, Shenyang, 110042, Liaoning, China
| | - Yu Zeng
- Department of Urology, Cancer Hospital of China Medical University, Liaoning Cancer Hospital and Institute, 44 Xiaoheyan Road, Shenyang, 110042, Liaoning, China.
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LeBlanc SJ, Kulkarni P, Weninger KR. Single Molecule FRET: A Powerful Tool to Study Intrinsically Disordered Proteins. Biomolecules 2018; 8:biom8040140. [PMID: 30413085 PMCID: PMC6315554 DOI: 10.3390/biom8040140] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 11/02/2018] [Accepted: 11/06/2018] [Indexed: 12/22/2022] Open
Abstract
Intrinsically disordered proteins (IDPs) are often modeled using ideas from polymer physics that suggest they smoothly explore all corners of configuration space. Experimental verification of this random, dynamic behavior is difficult as random fluctuations of IDPs cannot be synchronized across an ensemble. Single molecule fluorescence (or Förster) resonance energy transfer (smFRET) is one of the few approaches that are sensitive to transient populations of sub-states within molecular ensembles. In some implementations, smFRET has sufficient time resolution to resolve transitions in IDP behaviors. Here we present experimental issues to consider when applying smFRET to study IDP configuration. We illustrate the power of applying smFRET to IDPs by discussing two cases in the literature of protein systems for which smFRET has successfully reported phosphorylation-induced modification (but not elimination) of the disordered properties that have been connected to impacts on the related biological function. The examples we discuss, PAGE4 and a disordered segment of the GluN2B subunit of the NMDA receptor, illustrate the great potential of smFRET to inform how IDP function can be regulated by controlling the detailed ensemble of disordered states within biological networks.
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Affiliation(s)
- Sharonda J LeBlanc
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA.
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
| | - Prakash Kulkarni
- Department of Medical Oncology and Therapeutics Research, City of Hope National Medical Center, Duarte, CA 91010, USA.
| | - Keith R Weninger
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA.
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Prostate-Associated Gene 4 (PAGE4): Leveraging the Conformational Dynamics of a Dancing Protein Cloud as a Therapeutic Target. J Clin Med 2018; 7:jcm7060156. [PMID: 29914187 PMCID: PMC6025510 DOI: 10.3390/jcm7060156] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 06/13/2018] [Accepted: 06/15/2018] [Indexed: 12/24/2022] Open
Abstract
Prostate cancer (PCa) is a leading cause of mortality and morbidity globally. While genomic alterations have been identified in PCa, in contrast to some other cancers, use of such information to personalize treatment is still in its infancy. Here, we discuss how PAGE4, a protein which appears to act both as an oncogenic factor as well as a metastasis suppressor, is a novel therapeutic target for PCa. Inhibiting PAGE4 may be a viable strategy for low-risk PCa where it is highly upregulated. Conversely, PAGE4 expression is downregulated in metastatic PCa and, therefore, reinstituting its sustained expression may be a promising option to subvert or attenuate androgen-resistant PCa. Thus, fine-tuning the levels of PAGE4 may represent a novel approach for personalized medicine in PCa.
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16
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Lin X, Roy S, Jolly MK, Bocci F, Schafer NP, Tsai MY, Chen Y, He Y, Grishaev A, Weninger K, Orban J, Kulkarni P, Rangarajan G, Levine H, Onuchic JN. PAGE4 and Conformational Switching: Insights from Molecular Dynamics Simulations and Implications for Prostate Cancer. J Mol Biol 2018; 430:2422-2438. [PMID: 29758263 DOI: 10.1016/j.jmb.2018.05.011] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 04/13/2018] [Accepted: 05/07/2018] [Indexed: 11/15/2022]
Abstract
Prostate-associated gene 4 (PAGE4) is an intrinsically disordered protein implicated in prostate cancer. Thestress-response kinase homeodomain-interacting protein kinase 1 (HIPK1) phosphorylates two residues in PAGE4, serine 9 and threonine 51. Phosphorylation of these two residues facilitates the interaction of PAGE4 with activator protein-1 (AP-1) transcription factor complex to potentiate AP-1's activity. In contrast, hyperphosphorylation of PAGE4 by CDC-like kinase 2 (CLK2) attenuates this interaction with AP-1. Small-angleX-ray scattering and single-molecule fluorescence resonance energy transfer measurements have shown that PAGE4 expands upon hyperphosphorylation and that this expansion is localized to its N-terminal half. To understand the interactions underlying this structural transition, we performed molecular dynamics simulations using Atomistic AWSEM, a multi-scale molecular model that combines atomistic and coarse-grained simulation approaches. Our simulations show that electrostatic interactions drive transient formation of an N-terminal loop, the destabilization of which accounts for the dramatic change in size upon hyperphosphorylation. Phosphorylation also changes the preference of secondary structure formation of the PAGE4 ensemble, which leads to a transition between states that display different degrees of disorder. Finally, we construct a mechanism-based mathematical model that allows us to capture the interactions ofdifferent phosphoforms of PAGE4 with AP-1 and its downstream target, the androgen receptor (AR)-a key therapeutic target in prostate cancer. Our model predicts intracellular oscillatory dynamics of HIPK1-PAGE4, CLK2-PAGE4, and AR activity, indicating phenotypic heterogeneity in an isogenic cell population. Thus, conformational switching of PAGE4 may potentially affect the efficiency of therapeutically targeting AR activity.
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Affiliation(s)
- Xingcheng Lin
- Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, United States; Department of Physics and Astronomy, Rice University, Houston, TX 77005, United States
| | - Susmita Roy
- Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, United States
| | - Mohit Kumar Jolly
- Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, United States
| | - Federico Bocci
- Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, United States; Department of Chemistry, Rice University, Houston, TX 77005, United States
| | - Nicholas P Schafer
- Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, United States; Department of Chemistry, Rice University, Houston, TX 77005, United States
| | - Min-Yeh Tsai
- Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, United States; Department of Chemistry, Rice University, Houston, TX 77005, United States
| | - Yihong Chen
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850, United States
| | - Yanan He
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850, United States
| | - Alexander Grishaev
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850, United States; National Institute of Standards and Technology, Gaithersburg, MD 20899, United States
| | - Keith Weninger
- Department of Physics, North Carolina State University, Raleigh, NC 27695, United States
| | - John Orban
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850, United States; Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, United States
| | - Prakash Kulkarni
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850, United States; Department of Medical Oncology and Therapeutics Research, City of Hope National Medical Center, Duarte, CA 91010, United States
| | - Govindan Rangarajan
- Department of Mathematics, Indian Institute of Science, Bangalore 560012, India; Center for Neuroscience, Indian Institute of Science, Bangalore 560012, India
| | - Herbert Levine
- Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, United States; Department of Physics and Astronomy, Rice University, Houston, TX 77005, United States
| | - José N Onuchic
- Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, United States; Department of Physics and Astronomy, Rice University, Houston, TX 77005, United States; Department of Chemistry, Rice University, Houston, TX 77005, United States; Department of BioSciences, Rice University, Houston, TX 77005, United States.
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Jolly MK, Kulkarni P, Weninger K, Orban J, Levine H. Phenotypic Plasticity, Bet-Hedging, and Androgen Independence in Prostate Cancer: Role of Non-Genetic Heterogeneity. Front Oncol 2018; 8:50. [PMID: 29560343 PMCID: PMC5845637 DOI: 10.3389/fonc.2018.00050] [Citation(s) in RCA: 87] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2017] [Accepted: 02/19/2018] [Indexed: 12/21/2022] Open
Abstract
It is well known that genetic mutations can drive drug resistance and lead to tumor relapse. Here, we focus on alternate mechanisms-those without mutations, such as phenotypic plasticity and stochastic cell-to-cell variability that can also evade drug attacks by giving rise to drug-tolerant persisters. The phenomenon of persistence has been well-studied in bacteria and has also recently garnered attention in cancer. We draw a parallel between bacterial persistence and resistance against androgen deprivation therapy in prostate cancer (PCa), the primary standard care for metastatic disease. We illustrate how phenotypic plasticity and consequent mutation-independent or non-genetic heterogeneity possibly driven by protein conformational dynamics can stochastically give rise to androgen independence in PCa, and suggest that dynamic phenotypic plasticity should be considered in devising therapeutic dosing strategies designed to treat and manage PCa.
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Affiliation(s)
- Mohit Kumar Jolly
- Center for Theoretical Biological Physics, Rice University, Houston, TX, United States
| | - Prakash Kulkarni
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD, United States
| | - Keith Weninger
- Department of Physics, North Carolina State University, Raleigh, NC, United States
| | - John Orban
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD, United States
- Department of Chemistry and Biochemistry, University of Maryland, College Park, College Park, United States
| | - Herbert Levine
- Center for Theoretical Biological Physics, Rice University, Houston, TX, United States
- Department of Bioengineering, Rice University, Houston, TX, United States
- Department of Physics and Astronomy, Rice University, Houston, TX, United States
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Jia D, Jolly MK, Kulkarni P, Levine H. Phenotypic Plasticity and Cell Fate Decisions in Cancer: Insights from Dynamical Systems Theory. Cancers (Basel) 2017; 9:E70. [PMID: 28640191 PMCID: PMC5532606 DOI: 10.3390/cancers9070070] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 06/13/2017] [Accepted: 06/13/2017] [Indexed: 01/11/2023] Open
Abstract
Waddington's epigenetic landscape, a famous metaphor in developmental biology, depicts how a stem cell progresses from an undifferentiated phenotype to a differentiated one. The concept of "landscape" in the context of dynamical systems theory represents a high-dimensional space, in which each cell phenotype is considered as an "attractor" that is determined by interactions between multiple molecular players, and is buffered against environmental fluctuations. In addition, biological noise is thought to play an important role during these cell-fate decisions and in fact controls transitions between different phenotypes. Here, we discuss the phenotypic transitions in cancer from a dynamical systems perspective and invoke the concept of "cancer attractors"-hidden stable states of the underlying regulatory network that are not occupied by normal cells. Phenotypic transitions in cancer occur at varying levels depending on the context. Using epithelial-to-mesenchymal transition (EMT), cancer stem-like properties, metabolic reprogramming and the emergence of therapy resistance as examples, we illustrate how phenotypic plasticity in cancer cells enables them to acquire hybrid phenotypes (such as hybrid epithelial/mesenchymal and hybrid metabolic phenotypes) that tend to be more aggressive and notoriously resilient to therapies such as chemotherapy and androgen-deprivation therapy. Furthermore, we highlight multiple factors that may give rise to phenotypic plasticity in cancer cells, such as (a) multi-stability or oscillatory behaviors governed by underlying regulatory networks involved in cell-fate decisions in cancer cells, and (b) network rewiring due to conformational dynamics of intrinsically disordered proteins (IDPs) that are highly enriched in cancer cells. We conclude by discussing why a therapeutic approach that promotes "recanalization", i.e., the exit from "cancer attractors" and re-entry into "normal attractors", is more likely to succeed rather than a conventional approach that targets individual molecules/pathways.
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Affiliation(s)
- Dongya Jia
- Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, USA.
- Graduate Program in Systems, Synthetic and Physical Biology, Rice University, Houston, TX 77005, USA.
| | - Mohit Kumar Jolly
- Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, USA.
| | - Prakash Kulkarni
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850, USA.
| | - Herbert Levine
- Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, USA.
- Department of Bioengineering, Rice University, Houston, TX 77005, USA.
- Department of Physics and Astronomy, Rice University, Houston, TX 77005, USA.
- Department of Biosciences, Rice University, Houston, TX 77005, USA.
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19
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Cancer/Testis Antigens: "Smart" Biomarkers for Diagnosis and Prognosis of Prostate and Other Cancers. Int J Mol Sci 2017; 18:ijms18040740. [PMID: 28362316 PMCID: PMC5412325 DOI: 10.3390/ijms18040740] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2017] [Revised: 03/22/2017] [Accepted: 03/27/2017] [Indexed: 12/22/2022] Open
Abstract
A clinical dilemma in the management of prostate cancer (PCa) is to distinguish men with aggressive disease who need definitive treatment from men who may not require immediate intervention. Accurate prediction of disease behavior is critical because radical treatment is associated with high morbidity. Here, we highlight the cancer/testis antigens (CTAs) as potential PCa biomarkers. The CTAs are a group of proteins that are typically restricted to the testis in the normal adult but are aberrantly expressed in several types of cancers. Interestingly, >90% of CTAs are predicted to belong to the realm of intrinsically disordered proteins (IDPs), which do not have unique structures and exist as highly dynamic conformational ensembles, but are known to play important roles in several biological processes. Using prostate-associated gene 4 (PAGE4) as an example of a disordered CTA, we highlight how IDP conformational dynamics may regulate phenotypic heterogeneity in PCa cells, and how it may be exploited both as a potential biomarker as well as a promising therapeutic target in PCa. We also discuss how in addition to intrinsic disorder and post-translational modifications, structural and functional variability induced in the CTAs by alternate splicing represents an important feature that might have different roles in different cancers. Although it is clear that significant additional work needs to be done in the outlined direction, this novel concept emphasizing (multi)functionality as an important trait in selecting a biomarker underscoring the theranostic potential of CTAs that is latent in their structure (or, more appropriately, the lack thereof), and casts them as next generation or “smart” biomarker candidates.
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20
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Mooney SM, Jolly MK, Levine H, Kulkarni P. Phenotypic plasticity in prostate cancer: role of intrinsically disordered proteins. Asian J Androl 2017; 18:704-10. [PMID: 27427552 PMCID: PMC5000791 DOI: 10.4103/1008-682x.183570] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
A striking characteristic of cancer cells is their remarkable phenotypic plasticity, which is the ability to switch states or phenotypes in response to environmental fluctuations. Phenotypic changes such as a partial or complete epithelial to mesenchymal transition (EMT) that play important roles in their survival and proliferation, and development of resistance to therapeutic treatments, are widely believed to arise due to somatic mutations in the genome. However, there is a growing concern that such a deterministic view is not entirely consistent with multiple lines of evidence, which indicate that stochasticity may also play an important role in driving phenotypic plasticity. Here, we discuss how stochasticity in protein interaction networks (PINs) may play a key role in determining phenotypic plasticity in prostate cancer (PCa). Specifically, we point out that the key players driving transitions among different phenotypes (epithelial, mesenchymal, and hybrid epithelial/mesenchymal), including ZEB1, SNAI1, OVOL1, and OVOL2, are intrinsically disordered proteins (IDPs) and discuss how plasticity at the molecular level may contribute to stochasticity in phenotypic switching by rewiring PINs. We conclude by suggesting that targeting IDPs implicated in EMT in PCa may be a new strategy to gain additional insights and develop novel treatments for this disease, which is the most common form of cancer in adult men.
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Affiliation(s)
- Steven M Mooney
- Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1, Canada
| | - Mohit Kumar Jolly
- Center for Theoretical Biological Physics, Rice University, Houston, TX 77005; Department of Bioengineering, Rice University, Houston, TX 77005, USA
| | - Herbert Levine
- Center for Theoretical Biological Physics, Rice University, Houston, TX 77005; Department of Bioengineering, Rice University, Houston, TX 77005; Department of Physics and Astronomy, Rice University, Houston, TX 77005, USA
| | - Prakash Kulkarni
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, Maryland 20850, USA
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21
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Kulkarni P. Intrinsically disordered proteins and prostate cancer: pouring new wine in an old bottle. Asian J Androl 2017; 18:659-61. [PMID: 27427556 PMCID: PMC5000785 DOI: 10.4103/1008-682x.184272] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Affiliation(s)
- Prakash Kulkarni
- Protein Biophysics & Structural Biology Laboratory, Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850, USA
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22
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Kulkarni P, Dunker AK, Weninger K, Orban J. Prostate-associated gene 4 (PAGE4), an intrinsically disordered cancer/testis antigen, is a novel therapeutic target for prostate cancer. Asian J Androl 2017; 18:695-703. [PMID: 27270343 PMCID: PMC5000790 DOI: 10.4103/1008-682x.181818] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Prostate-associated gene 4 (PAGE4) is a remarkably prostate-specific Cancer/Testis Antigen that is highly upregulated in the human fetal prostate and its diseased states but not in the adult normal gland. PAGE4 is an intrinsically disordered protein (IDP) that functions as a stress-response protein to suppress reactive oxygen species as well as prevent DNA damage. In addition, PAGE4 is also a transcriptional regulator that potentiates transactivation by the oncogene c-Jun. c-Jun forms the AP-1 complex by heterodimerizing with members of the Fos family and plays an important role in the development and pathology of the prostate gland, underscoring the importance of the PAGE4/c-Jun interaction. HIPK1, also a component of the stress-response pathway, phosphorylates PAGE4 at T51 which is critical for its transcriptional activity. Phosphorylation induces conformational and dynamic switching in the PAGE4 ensemble leading to a new cellular function. Finally, bioinformatics evidence suggests that the PAGE4 mRNA could be alternatively spliced resulting in four potential isoforms of the polypeptide alluding to the possibility of a range of conformational ensembles with latent functions. Considered together, the data suggest that PAGE4 may represent the first molecular link between stress and prostate cancer (PCa). Thus, pharmacologically targeting PAGE4 may be a novel opportunity for treating and managing patients with PCa, especially patients with low-risk disease.
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Affiliation(s)
- Prakash Kulkarni
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850, USA
| | - A Keith Dunker
- Center for Computational Biology and Bioinformatics, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine and Informatics, Indianapolis, IN 46202, USA
| | - Keith Weninger
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA
| | - John Orban
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850; Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA
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23
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Phosphorylation-induced conformational dynamics in an intrinsically disordered protein and potential role in phenotypic heterogeneity. Proc Natl Acad Sci U S A 2017; 114:E2644-E2653. [PMID: 28289210 DOI: 10.1073/pnas.1700082114] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Intrinsically disordered proteins (IDPs) that lack a unique 3D structure and comprise a large fraction of the human proteome play important roles in numerous cellular functions. Prostate-Associated Gene 4 (PAGE4) is an IDP that acts as a potentiator of the Activator Protein-1 (AP-1) transcription factor. Homeodomain-Interacting Protein Kinase 1 (HIPK1) phosphorylates PAGE4 at S9 and T51, but only T51 is critical for its activity. Here, we identify a second kinase, CDC-Like Kinase 2 (CLK2), which acts on PAGE4 and hyperphosphorylates it at multiple S/T residues, including S9 and T51. We demonstrate that HIPK1 is expressed in both androgen-dependent and androgen-independent prostate cancer (PCa) cells, whereas CLK2 and PAGE4 are expressed only in androgen-dependent cells. Cell-based studies indicate that PAGE4 interaction with the two kinases leads to opposing functions. HIPK1-phosphorylated PAGE4 (HIPK1-PAGE4) potentiates c-Jun, whereas CLK2-phosphorylated PAGE4 (CLK2-PAGE4) attenuates c-Jun activity. Consistent with the cellular data, biophysical measurements (small-angle X-ray scattering, single-molecule fluorescence resonance energy transfer, and NMR) indicate that HIPK1-PAGE4 exhibits a relatively compact conformational ensemble that binds AP-1, whereas CLK2-PAGE4 is more expanded and resembles a random coil with diminished affinity for AP-1. Taken together, the results suggest that the phosphorylation-induced conformational dynamics of PAGE4 may play a role in modulating changes between PCa cell phenotypes. A mathematical model based on our experimental data demonstrates how differential phosphorylation of PAGE4 can lead to transitions between androgen-dependent and androgen-independent phenotypes by altering the AP-1/androgen receptor regulatory circuit in PCa cells.
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Roscovitine Protects From Arterial Injury by Regulating the Expressions of c-Jun and p27 and Inhibiting Vascular Smooth Muscle Cell Proliferation. J Cardiovasc Pharmacol 2017; 69:161-169. [DOI: 10.1097/fjc.0000000000000453] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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25
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Mooney SM, Rajagopalan K, Rangarajan G, Kulkarni P. Cancer/testis antigens and obligate participation in multiple hallmarks of cancer: an update. Asian J Androl 2016; 18:711-2. [PMID: 26908068 PMCID: PMC5000792 DOI: 10.4103/1008-682x.174858] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The Cancer/Testis Antigens (CTAs) are a group of so-called tumor antigens that exhibit provocative expression patterns in most types of cancer. However, because most CTAs appear to be intrinsically disordered, they are recalcitrant to classical structural studies. Thus, the functions of most, if not all, CTAs have remained elusive and their potential as pharmacological targets in cancer has remained largely unexplored. In this viewpoint, we suggest that perhaps, an integrative approach applying dynamical systems theory and a system-level perspective rather a merely reductionist view, may shine new light on these enigmatic molecules.
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Affiliation(s)
- Steven M Mooney
- Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1, Canada
| | | | - Govindan Rangarajan
- Department of Mathematics and Centre for Neuroscience, Indian Institute of Science, Bengaluru, Karnataka, India
| | - Prakash Kulkarni
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, Maryland 20850, USA
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26
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Kulkarni P, Getzenberg RH. Disorder, Promiscuous Interactions, and Stochasticity Regulate State Switching in the Unstable Prostate. J Cell Biochem 2016; 117:2235-40. [PMID: 27152744 DOI: 10.1002/jcb.25578] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 05/02/2016] [Indexed: 12/12/2022]
Abstract
A causal link between benign prostatic hyperplasia (BPH) and prostate cancer has long been suspected but not widely accepted. A new model is proposed that supports such a connection. In contrast to the prevailing wisdom, our model, that draws on dynamical systems theory, suggests that in response to stress, epithelial cells in the unstable gland can give rise to both types of diseases via a phenotypic switching mechanism. The central idea is that phenotypic switching is a stochastic process which exploits the plasticity of the epithelial cell. It is driven by 'noise' contributed by the conformational dynamics of proteins that are intrinsically disordered. In a system that is noisy when stressed, disorder promotes promiscuity, unmasks latent information, and rewires the network to cause phenotypic switching. Cells with newly acquired phenotypes can transcend the traditional zonal boundaries to give rise to BPH or prostate cancer depending on the microenvironment. Establishing causality between the two diseases may provide us with an opportunity to better understand their etiology and guide prevention and treatment strategies. J. Cell. Biochem. 117: 2235-2240, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Prakash Kulkarni
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, Maryland
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DeForte S, Reddy KD, Uversky VN. Quarterly intrinsic disorder digest (January-February-March, 2014). INTRINSICALLY DISORDERED PROTEINS 2016; 4:e1153395. [PMID: 28232896 DOI: 10.1080/21690707.2016.1153395] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
This is the 5th issue of the Digested Disorder series that represents a reader's digest of the scientific literature on intrinsically disordered proteins. We continue to use only 2 criteria for inclusion of a paper to this digest: The publication date (a paper should be published within the covered time frame) and the topic (a paper should be dedicated to any aspect of protein intrinsic disorder). The current digest issue covers papers published during the first quarter of 2014; i.e., during the period of January, February, and March of 2014. Similar to previous issues, the papers are grouped hierarchically by topics they cover, and for each of the included papers a short description is given on its major findings.
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Affiliation(s)
- Shelly DeForte
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida , Tampa, FL, USA
| | - Krishna D Reddy
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida , Tampa, FL, USA
| | - Vladimir N Uversky
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, USA; USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL, USA; Biology Department, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia; Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russia
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28
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Mooney SM, Parsana P, Hernandez JR, Liu X, Verdone JE, Torga G, Harberg CA, Pienta KJ. The presence of androgen receptor elements regulates ZEB1 expression in the absence of androgen receptor. J Cell Biochem 2016; 116:115-23. [PMID: 25160502 DOI: 10.1002/jcb.24948] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 08/22/2014] [Indexed: 01/17/2023]
Abstract
Zinc finger E-box binding homeobox 1 (ZEB1) is a transcription factor that plays a central role in the epithelial to mesenchymal transition (EMT) of cancer cell lines. Studies on its regulation have mostly focused on the negative 3'UTR binding of miR200c. Interestingly, it has been previously reported that androgen receptor (AR) regulates ZEB1 expression in breast and prostate cancers. In order to validate this, various ZEB1 promoter deletions were cloned into a luciferase reporter system to elucidate the contribution of two putative androgen response elements (AREs). The in vivo contribution of AR was also assessed in cell lines after R1881 treatment using qPCR with prostate specific antigen (PSA) as the positive control. We discovered that AR upregulates the levels of expression of ZEB1 10-fold on a luciferase promoter that only contains the distal ARE. However, when the proximal ARE is included, no additional activation is apparent with AR or its hormone independent variant, AR-V7. Furthermore, we demonstrate here that a promoter construct containing both AREs activates transcription of ZEB1 even in the AR-null cell lines DU145 and PC3. Incubation of the AR-positive cell line, LNCaP with R1881, failed to substantially increase the expression levels of ZEB1. Despite the presence of AREs in the promoter region, it appears that ZEB1 expression can be induced even without AR. In addition, the region around the distal ARE is a potent repressor in AR-null cell lines.
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Affiliation(s)
- Steven M Mooney
- The James Buchanan Brady Urological Institute and Department of Urology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, 21287
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He Y, Chen Y, Mooney SM, Rajagopalan K, Bhargava A, Sacho E, Weninger K, Bryan PN, Kulkarni P, Orban J. Phosphorylation-induced Conformational Ensemble Switching in an Intrinsically Disordered Cancer/Testis Antigen. J Biol Chem 2015; 290:25090-102. [PMID: 26242913 DOI: 10.1074/jbc.m115.658583] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Indexed: 11/06/2022] Open
Abstract
Prostate-associated gene 4 (PAGE4) is an intrinsically disordered cancer/testis antigen that is up-regulated in the fetal and diseased human prostate. Knocking down PAGE4 expression results in cell death, whereas its overexpression leads to a growth advantage of prostate cancer cells (Zeng, Y., He, Y., Yang, F., Mooney, S. M., Getzenberg, R. H., Orban, J., and Kulkarni, P. (2011) The cancer/testis antigen prostate-associated gene 4 (PAGE4) is a highly intrinsically disordered protein. J. Biol. Chem. 286, 13985-13994). Phosphorylation of PAGE4 at Thr-51 is critical for potentiating c-Jun transactivation, an important factor in controlling cell growth, apoptosis, and stress response. Using NMR spectroscopy, we show that the PAGE4 polypeptide chain has local and long-range conformational preferences that are perturbed by site-specific phosphorylation at Thr-51. The population of transient turn-like structures increases upon phosphorylation in an ∼20-residue acidic region centered on Thr-51. This central region therefore becomes more compact and more negatively charged, with increasing intramolecular contacts to basic sequence motifs near the N and C termini. Although flexibility is decreased in the central region of phospho-PAGE4, the polypeptide chain remains highly dynamic overall. PAGE4 utilizes a transient helical structure adjacent to the central acidic region to bind c-Jun with low affinity in vitro. The binding interaction is attenuated by phosphorylation at Thr-51, most likely because of masking the effects of the more compact phosphorylated state. Therefore, phosphorylation of PAGE4 leads to conformational shifts in the dynamic ensemble, with large functional consequences. The changes in the structural ensemble induced by posttranslational modifications are similar conceptually to the conformational switching events seen in some marginally stable ("metamorphic") folded proteins in response to mutation or environmental triggers.
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Affiliation(s)
- Yanan He
- From the W. M. Keck Laboratory for Structural Biology, University of Maryland Institute for Bioscience and Biotechnology Research, Rockville, Maryland 20850, the Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742
| | - Yihong Chen
- From the W. M. Keck Laboratory for Structural Biology, University of Maryland Institute for Bioscience and Biotechnology Research, Rockville, Maryland 20850, the Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742
| | - Steven M Mooney
- the Department of Urology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287
| | - Krithika Rajagopalan
- the Department of Urology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287
| | - Ajay Bhargava
- Shakti BioResearch, Woodbridge, Connecticut 06525, and
| | - Elizabeth Sacho
- the Department of Physics, North Carolina State University, Raleigh, North Carolina 27695
| | - Keith Weninger
- the Department of Physics, North Carolina State University, Raleigh, North Carolina 27695
| | - Philip N Bryan
- From the W. M. Keck Laboratory for Structural Biology, University of Maryland Institute for Bioscience and Biotechnology Research, Rockville, Maryland 20850
| | - Prakash Kulkarni
- the Department of Urology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287,
| | - John Orban
- From the W. M. Keck Laboratory for Structural Biology, University of Maryland Institute for Bioscience and Biotechnology Research, Rockville, Maryland 20850, the Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742,
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Alternative CD44 splicing identifies epithelial prostate cancer cells from the mesenchymal counterparts. Med Oncol 2015; 32:159. [PMID: 25850653 PMCID: PMC4391735 DOI: 10.1007/s12032-015-0593-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 03/16/2015] [Indexed: 12/21/2022]
Abstract
An epithelial to mesenchymal transition (EMT) has been shown to be a necessary precursor to prostate cancer metastasis. Additionally, the differential expression and splicing of mRNAs has been identified as a key means to distinguish epithelial from mesenchymal cells by qPCR, western blotting and immunohistochemistry. However, few markers exist to differentiate between these cells by flow cytometry. We previously developed two cell lines, PC3-Epi (epithelial) and PC3-EMT (mesenchymal). RNAseq was used to determine the differential expression of membrane proteins on PC3-Epi/EMT. We used western blotting, qPCR and flow cytometry to validate the RNAseq results. CD44 was one of six membrane proteins found to be differentially spliced between epithelial and mesenchymal PC3 cells. Although total CD44 was positive in all PC3-Epi/EMT cells, PC3-Epi cells had a higher level of CD44v6 (CD44 variant exon 6). CD44v6 was able to differentiate epithelial from mesenchymal prostate cancer cells using either flow cytometry, western blotting or qPCR.
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Mooney SM, Qiu R, Kim JJ, Sacho EJ, Rajagopalan K, Johng D, Shiraishi T, Kulkarni P, Weninger KR. Cancer/testis antigen PAGE4, a regulator of c-Jun transactivation, is phosphorylated by homeodomain-interacting protein kinase 1, a component of the stress-response pathway. Biochemistry 2014; 53:1670-9. [PMID: 24559171 PMCID: PMC4198062 DOI: 10.1021/bi500013w] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
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Prostate-associated gene 4 (PAGE4)
is a cancer/testis antigen that
is typically restricted to the testicular germ cells but is aberrantly
expressed in cancer. Furthermore, PAGE4 is developmentally regulated
with dynamic expression patterns in the developing prostate and is
also a stress-response protein that is upregulated in response to
cellular stress. PAGE4 interacts with c-Jun, which is activated by
the stress-response kinase JNK1, and plays an important role in the
development and pathology of the prostate gland. Here, we have identified
homeodomain-interacting protein kinase 1 (HIPK1), also a component
of the stress-response pathway, as a kinase that phosphorylates PAGE4
at T51. We show that phosphorylation of PAGE4 is critical for its
transcriptional activity since mutating this T residue abolishes its
ability to potentiate c-Jun transactivation. In vitro single molecule FRET indicates phosphorylation results in compaction
of (still) intrinsically disordered PAGE4. Interestingly, however,
while our previous observations indicated that the wild-type nonphosphorylated
PAGE4 protein interacted with c-Jun [RajagopalanK. et al. (2014) 1842, 154−16324263171], here we show that phosphorylation of PAGE4
weakens its interaction with c-Jun in vitro. These
data suggest that phosphorylation induces conformational changes in
natively disordered PAGE4 resulting in its decreased affinity for
c-Jun to promote interaction of c-Jun with another, unidentified,
partner. Alternatively, phosphorylated PAGE4 may induce transcription
of a novel partner, which then potentiates c-Jun transactivation.
Regardless, the present results clearly implicate PAGE4 as a component
of the stress-response pathway and uncover a novel link between components
of this pathway and prostatic development and disease.
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Affiliation(s)
- Steven M Mooney
- The James Buchanan Brady Urological Institute and Department of Urology, ‡Oncology, §Cellular and Molecular Medicine, and ∥Department of Biomedical Engineering, Whiting School of Engineering, The Johns Hopkins University School of Medicine , 733 North Broadway, Baltimore, Maryland 21205, United States
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