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Weber DK, Reddy UV, Robia SL, Veglia G. Pathological mutations in the phospholamban cytoplasmic region affect its topology and dynamics modulating the extent of SERCA inhibition. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2024; 1866:184370. [PMID: 38986894 DOI: 10.1016/j.bbamem.2024.184370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Revised: 06/26/2024] [Accepted: 07/02/2024] [Indexed: 07/12/2024]
Abstract
Phospholamban (PLN) is a 52 amino acid regulin that allosterically modulates the activity of the sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) in the heart muscle. In its unphosphorylated form, PLN binds SERCA within its transmembrane (TM) domains, approximately 20 Å away from the Ca2+ binding site, reducing SERCA's apparent Ca2+ affinity (pKCa) and decreasing cardiac contractility. During the enzymatic cycle, the inhibitory TM domain of PLN remains anchored to SERCA, whereas its cytoplasmic region transiently binds the ATPase's headpiece. Phosphorylation of PLN at Ser16 by protein kinase A increases the affinity of its cytoplasmic domain to SERCA, weakening the TM interactions with the ATPase, reversing its inhibitory function, and augmenting muscle contractility. How the structural changes caused by pathological mutations in the PLN cytoplasmic region are transmitted to its inhibitory TM domain is still unclear. Using solid-state NMR spectroscopy and activity assays, we analyzed the structural and functional effects of a series of mutations and their phosphorylated forms located in the PLN cytoplasmic region and linked to dilated cardiomyopathy. We found that these missense mutations affect the overall topology and dynamics of PLN and ultimately modulate its inhibitory potency. Also, the changes in the TM tilt angle and cytoplasmic dynamics of PLN caused by these mutations correlate well with the extent of SERCA inhibition. Our study unveils new molecular determinants for designing variants of PLN that outcompete endogenous PLN to regulate SERCA in a tunable manner.
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Affiliation(s)
- Daniel K Weber
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - U Venkateswara Reddy
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Seth L Robia
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL, USA
| | - Gianluigi Veglia
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA.
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Yu Q, Barndt RJ, Shen Y, Sallam K, Tang Y, Chan SY, Wu JC, Liu Q, Wu H. Mitigation of Stress-induced Structural Remodeling and Functional Deficiency in iPSC-CMs with PLN R9C Mutation by Promoting Autophagy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.17.589921. [PMID: 38659742 PMCID: PMC11042320 DOI: 10.1101/2024.04.17.589921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Background Phospholamban (PLN) is a key regulator of cardiac function connecting adrenergic signaling and calcium homeostasis. The R9C mutation of PLN is known to cause early onset dilated cardiomyopathy (DCM) and premature death, yet the detailed mechanisms underlie the pathologic remodeling process are not well defined in human cardiomyocytes. The aim of this study is to unravel the role of PLN R9C in DCM and identify potential therapeutic targets. Methods PLN R9C knock-in (KI) and patient-specific induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) were generated and comprehensively examined for their expression profile, contractile function, and cellular signaling under both baseline conditions and following functional challenges. Results PLN R9C KI iPSC-CMs exhibited near-normal morphology and calcium handling, slightly increased contractility, and an attenuated response to β-adrenergic activation compared to wild-type (WT) cells. However, treatment with a maturation medium (MM) has induced fundamentally different remodeling in the two groups: while it improved the structural integrity and functional performance of WT cells, the same treatment result in sarcomere disarrangement, calcium handling deficiency, and further disrupted adrenergic signaling in PLN R9C KI cells. To understand the mechanism, transcriptomic analysis showed the enrichment of protein homeostasis signaling pathways specifically in PLN R9C KI cells in response to the MM treatment and increased contractile demands. Further studies also indicated elevated ROS levels, interrupted autophagic flux, and increased pentamer PLN aggregation in functionally challenged KI cells. These results were further confirmed in patient-specific iPSC-CM models, suggesting that functional stresses exacerbate the deficiencies in PLN R9C cells through disrupting protein homeostasis. Indeed, treating stressed patient cells with autophagy-accelerating reagents, such as metformin and rapamycin, has restored autophagic flux, mitigated sarcomere disarrangement, and partially rescued β-adrenergic signaling and cardiac function. Conclusions PLN R9C leads to a mild increase of calcium recycling and contractility. Functional challenges further enhanced contractile and proteostasis stress, leading to autophagic overload, structural remodeling, and functional deficiencies in PLN R9C cardiomyocytes. Activation of autophagy signaling partially rescues these effects, revealing a potential therapeutic target for DCM patients with the PLN R9C mutation. Graphic abstracts A graphic abstract is available for this article.
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Understanding the Role of SERCA2a Microdomain Remodeling in Heart Failure Induced by Obesity and Type 2 Diabetes. J Cardiovasc Dev Dis 2022; 9:jcdd9050163. [PMID: 35621874 PMCID: PMC9147026 DOI: 10.3390/jcdd9050163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 04/21/2022] [Accepted: 04/25/2022] [Indexed: 11/29/2022] Open
Abstract
Obesity and type 2 diabetes (T2D) are on trend to become a huge burden across all ages. They cause harm to almost every organ, especially the heart. For decades, the incidence of heart failure with impaired diastolic function (or called heart failure with preserved ejection fraction, HFpEF) has increased sharply. More and more studies have uncovered obesity and T2D to be closely associated with HFpEF. The sarcoplasmic/endoplasmic reticulum calcium ATPase2a (SERCA2a) microdomain is a key regulator of calcium reuptake into the sarcoplasmic reticulum (SR) during diastole. 3′,5′-cyclic adenosine monophosphate (cAMP) and its downstream effector cAMP dependent protein kinase (PKA) act locally within the SERCA2a microdomain to regulate the phosphorylation state of the small regulatory protein phospholamban (PLN), which forms a complex with SERCA2a. When phosphorylated, PLN promotes calcium reuptake into the SR and diastolic cardiac relaxation by disinhibiting SERCA2a pump function. In this review, we will discuss previous studies investigating the PLN/SERCA2a microdomain in obesity and T2D in order to gain a greater understanding of the underlying mechanisms behind obesity- and T2D-induced diastolic dysfunction, with the aim to identify the current state of knowledge and future work that is needed to guide further research in the field.
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Qin J, Zhang J, Lin L, Haji-Ghassemi O, Lin Z, Woycechowsky KJ, Van Petegem F, Zhang Y, Yuchi Z. Structures of PKA-phospholamban complexes reveal a mechanism of familial dilated cardiomyopathy. eLife 2022; 11:75346. [PMID: 35297759 PMCID: PMC8970585 DOI: 10.7554/elife.75346] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 03/16/2022] [Indexed: 01/07/2023] Open
Abstract
Several mutations identified in phospholamban (PLN) have been linked to familial dilated cardiomyopathy (DCM) and heart failure, yet the underlying molecular mechanism remains controversial. PLN interacts with sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) and regulates calcium uptake, which is modulated by the protein kinase A (PKA)-dependent phosphorylation of PLN during the fight-or-flight response. Here, we present the crystal structures of the catalytic domain of mouse PKA in complex with wild-type and DCM-mutant PLNs. Our structures, combined with the results from other biophysical and biochemical assays, reveal a common disease mechanism: the mutations in PLN reduce its phosphorylation level by changing its conformation and weakening its interactions with PKA. In addition, we demonstrate that another more ubiquitous SERCA-regulatory peptide, called another-regulin (ALN), shares a similar mechanism mediated by PKA in regulating SERCA activity.
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Affiliation(s)
- Juan Qin
- Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency; Collaborative Innovation Center of Chemical Science and Engineering; School of Pharmaceutical Science and Technology, Tianjin UniversityTianjinChina
| | - Jingfeng Zhang
- Wuhan Institute of Physics and Mathematics, Chinese Academy of SciencesWuhanChina
| | - Lianyun Lin
- Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency; Collaborative Innovation Center of Chemical Science and Engineering; School of Pharmaceutical Science and Technology, Tianjin UniversityTianjinChina
| | - Omid Haji-Ghassemi
- Department of Biochemistry and Molecular Biology, The Life Sciences Centre, University of British ColumbiaVancouverCanada
| | - Zhi Lin
- School of Life Sciences, Tianjin UniversityTianjinChina
| | - Kenneth J Woycechowsky
- Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency; Collaborative Innovation Center of Chemical Science and Engineering; School of Pharmaceutical Science and Technology, Tianjin UniversityTianjinChina
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, The Life Sciences Centre, University of British ColumbiaVancouverCanada
| | - Yan Zhang
- Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency; Collaborative Innovation Center of Chemical Science and Engineering; School of Pharmaceutical Science and Technology, Tianjin UniversityTianjinChina
| | - Zhiguang Yuchi
- Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency; Collaborative Innovation Center of Chemical Science and Engineering; School of Pharmaceutical Science and Technology, Tianjin UniversityTianjinChina,Department of Molecular Pharmacology, Tianjin Medical University Cancer Institute & Hospital; National Clinical Research Center for Cancer; Key Laboratory of Cancer Prevention and Therapy, Tianjin; Tianjin’s Clinical Research Center for CancerTianjinChina
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5
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Jiang X, Xu Y, Sun J, Wang L, Guo X, Chen Y. The phenotypic characteristic observed by cardiac magnetic resonance in a PLN-R14del family. Sci Rep 2020; 10:16478. [PMID: 33020536 PMCID: PMC7536202 DOI: 10.1038/s41598-020-73359-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Accepted: 09/03/2020] [Indexed: 02/05/2023] Open
Abstract
Phospholamban (PLN) is an important regulator for sarcoendoplasmic reticulum (SR) calcium transport ATPase (SERCA), which uptakes Ca2+ to SR during the diastolic phase of cardiomyocytes to maintain intracellular calcium homeostasis. Mutations on PLN result in intracellular calcium disorder, myocardial contraction defect, and eventually heart failure and/or malignant ventricular arrhythmia. Since 2003, several kinds of PLN mutations have been identified in familial dilated cardiomyopathy (DCM) patients, illustrating a few clinical characteristics that differs from classical DCM patients. Herein, we report a large PLN-R14del family with typical clinical characteristics reported including relatively late-onset clinical symptoms, low-voltage in ECG, as well as frequent ventricular arrythmias. Moreover, members underwent cardiac magnetic resonance (CMR) examination showed a strikingly similar pattern of late gadolinium enhancement (LGE)—Sub-epicardial involvement in the left ventricular (LV) lateral wall with or without linear mid-wall enhancement in the interventricular septum. The former one can also present in younger PLN-R14del carriers despite completely normal LV structure and function. Meanwhile, T1 mapping also found significantly increased extracellular volume (ECV) in PLN-R14del carriers. These findings highlight the special role of CMR to phenotyping PLN-induced cardiomyopathy patients and distinguish them from other types of cardiomyopathy.
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Affiliation(s)
- Xincheng Jiang
- Department of Cardiology, West China Hospital, Sichuan University, Guoxue Xiang No. 37, Chengdu, Sichuan, 610041, People's Republic of China
| | - Yuanwei Xu
- Department of Cardiology, West China Hospital, Sichuan University, Guoxue Xiang No. 37, Chengdu, Sichuan, 610041, People's Republic of China
| | - Jiayu Sun
- Department of Radiology, West China Hospital, Sichuan University, Chengdu, 610041, Sichuan, China
| | - Lili Wang
- Department of Cardiology, West China Hospital, Sichuan University, Guoxue Xiang No. 37, Chengdu, Sichuan, 610041, People's Republic of China
| | - Xinli Guo
- Department of Cardiology, West China Hospital, Sichuan University, Guoxue Xiang No. 37, Chengdu, Sichuan, 610041, People's Republic of China
| | - Yucheng Chen
- Department of Cardiology, West China Hospital, Sichuan University, Guoxue Xiang No. 37, Chengdu, Sichuan, 610041, People's Republic of China.
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Gopinath T, Veglia G. Proton-detected polarization optimized experiments (POE) using ultrafast magic angle spinning solid-state NMR: Multi-acquisition of membrane protein spectra. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2020; 310:106664. [PMID: 31837552 PMCID: PMC7003683 DOI: 10.1016/j.jmr.2019.106664] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 11/26/2019] [Accepted: 11/27/2019] [Indexed: 05/05/2023]
Abstract
Proton-detected solid-state NMR (ssNMR) spectroscopy has dramatically improved the sensitivity and resolution of fast magic angle spinning (MAS) methods. While relatively straightforward for fibers and crystalline samples, the routine application of these techniques to membrane protein samples is still challenging. This is due to the low sensitivity of these samples, which require high lipid:protein ratios to maintain the structural and functional integrity of membrane proteins. We previously introduced a family of novel polarization optimized experiments (POE) that enable to make the best of nuclear polarization and obtain multiple-acquisitions from a single pulse sequence and one receiver. Here, we present the 1H-detected versions of POE using ultrafast MAS ssNMR. Specifically, we implemented proton detection into our three main POE strategies, H-DUMAS, H-MEIOSIS, and H-MAeSTOSO, achieving the acquisition of up to ten different experiments using a single pulse sequence. We tested these experiments on a model compound N-Acetyl-Val-Leu dipeptide and applied to a six transmembrane acetate transporter, SatP, reconstituted in lipid membranes. These new methods will speed up the spectroscopy of challenging biomacromolecules such as membrane proteins.
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Affiliation(s)
- T Gopinath
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, United States
| | - Gianluigi Veglia
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, United States; Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, United States.
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7
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Larsen EK, Weber DK, Wang S, Gopinath T, Blackwell DJ, Dalton MP, Robia SL, Gao J, Veglia G. Intrinsically disordered HAX-1 regulates Ca 2+ cycling by interacting with lipid membranes and the phospholamban cytoplasmic region. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2020; 1862:183034. [PMID: 31400305 PMCID: PMC6899184 DOI: 10.1016/j.bbamem.2019.183034] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 07/09/2019] [Accepted: 07/30/2019] [Indexed: 01/14/2023]
Abstract
Hematopoietic-substrate-1 associated protein X-1 (HAX-1) is a 279 amino acid protein expressed ubiquitously. In cardiac muscle, HAX-1 was found to modulate the sarcoendoplasmic reticulum calcium ATPase (SERCA) by shifting its apparent Ca2+ affinity (pCa). It has been hypothesized that HAX-1 binds phospholamban (PLN), enhancing its inhibitory function on SERCA. HAX-1 effects are reversed by cAMP-dependent protein kinase A that phosphorylates PLN at Ser16. To date, the molecular mechanisms for HAX-1 regulation of the SERCA/PLN complex are still unknown. Using enzymatic, in cell assays, circular dichroism, and NMR spectroscopy, we found that in the absence of a binding partner HAX-1 is essentially disordered and adopts a partial secondary structure upon interaction with lipid membranes. Also, HAX-1 interacts with the cytoplasmic region of monomeric and pentameric PLN as detected by NMR and in cell FRET assays, respectively. We propose that the regulation of the SERCA/PLN complex by HAX-1 is mediated by its interactions with lipid membranes, adding another layer of control in Ca2+ homeostatic balance in the heart muscle.
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Affiliation(s)
- Erik K Larsen
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Daniel K Weber
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Songlin Wang
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Tata Gopinath
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | | | - Michael P Dalton
- Department of Physiology, Loyola University, Maywood, IL 60153, USA
| | - Seth L Robia
- Department of Physiology, Loyola University, Maywood, IL 60153, USA
| | - Jiali Gao
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA; School of Chemical Biology and Technology, Beijing University Graduate School, Shenzhen 518055, China
| | - Gianluigi Veglia
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA; Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA.
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8
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V S M, Gopinath T, Wang S, Veglia G. T 2* weighted Deconvolution of NMR Spectra: Application to 2D Homonuclear MAS Solid-State NMR of Membrane Proteins. Sci Rep 2019; 9:8225. [PMID: 31160739 PMCID: PMC6546711 DOI: 10.1038/s41598-019-44461-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 05/01/2019] [Indexed: 11/14/2022] Open
Abstract
2D homonuclear NMR spectroscopy is an essential technique to characterize small and large molecules, such as organic compounds, metabolites, and biomacromolecules at atomic resolution. However, for complex samples 2D homonuclear spectra display poor resolution, making spectral assignment very cumbersome. Here, we propose a new method that exploits the differential T2* relaxation times of individual resonances and resolves the 2D NMR peaks into pseudo-3D spectra, where time is the 3rd dimension. T2* weIghted DEconvolution or TIDE analyzes individual free induction decays (FIDs) and dissects them into sub-FIDs that are transformed into pseudo-3D spectra combining Fourier transformation and covariance NMR. TIDE achieves higher resolution and sensitivity for NMR spectra than classical covariance NMR reducing offset-dependent artifacts. We demonstrate the performance of TIDE for magic angle spinning (MAS) [13C,13C]-DARR NMR spectra of single- and multi-span membrane proteins embedded in lipid bilayers. Since TIDE is applicable to all type of homonuclear correlation experiments for liquid and solid samples, we anticipate that it will be a general method for processing NMR data of biomacromolecules, complex mixtures of metabolites as well as material samples.
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Affiliation(s)
- Manu V S
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA
| | - Tata Gopinath
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA
| | - Songlin Wang
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA
| | - Gianluigi Veglia
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA.
- Department of Chemistry, University of Minnesota, Minneapolis, MN, USA.
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9
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Gopinath T, Veglia G. Probing membrane protein ground and conformationally excited states using dipolar- and J-coupling mediated MAS solid state NMR experiments. Methods 2018; 148:115-122. [PMID: 30012515 PMCID: PMC6428079 DOI: 10.1016/j.ymeth.2018.07.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 07/10/2018] [Accepted: 07/11/2018] [Indexed: 12/25/2022] Open
Abstract
The intrinsic conformational plasticity of membrane proteins directly influences the magnitude of the orientational-dependent NMR interactions such as dipolar couplings (DC) and chemical shift anisotropy (CSA). As a result, the conventional cross-polarization (CP)-based techniques mainly capture the more rigid regions of membrane proteins, while the most dynamic regions are essentially invisible. Nonetheless, dynamic regions can be detected using experiments in which polarization transfer takes place via J-coupling interactions. Here, we review our recent efforts to develop single and dual acquisition pulse sequences with either 1H or 13C detection that utilize both DC and J-coupling mediated transfer to detect both rigid and mobile regions of membrane proteins in native-like lipid environments. We show the application of these new methods for studying the conformational equilibrium of a single-pass membrane protein, phospholamban, which regulates the calcium transport across the sarcoplasmic reticulum (SR) membrane by interacting with the SR Ca2+-ATPase. We anticipate that these methods will be ideal to portray the complex dynamics of membrane proteins in their native environments.
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Affiliation(s)
- T Gopinath
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, United States
| | - Gianluigi Veglia
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, United States; Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, United States.
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10
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Targeting protein-protein interactions for therapeutic discovery via FRET-based high-throughput screening in living cells. Sci Rep 2018; 8:12560. [PMID: 30135432 PMCID: PMC6105598 DOI: 10.1038/s41598-018-29685-z] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Accepted: 07/16/2018] [Indexed: 01/16/2023] Open
Abstract
We have developed a structure-based high-throughput screening (HTS) method, using time-resolved fluorescence resonance energy transfer (TR-FRET) that is sensitive to protein-protein interactions in living cells. The membrane protein complex between the cardiac sarcoplasmic reticulum Ca-ATPase (SERCA2a) and phospholamban (PLB), its Ca-dependent regulator, is a validated therapeutic target for reversing cardiac contractile dysfunction caused by aberrant calcium handling. However, efforts to develop compounds with SERCA2a-PLB specificity have yet to yield an effective drug. We co-expressed GFP-SERCA2a (donor) in the endoplasmic reticulum membrane of HEK293 cells with RFP-PLB (acceptor), and measured FRET using a fluorescence lifetime microplate reader. We screened a small-molecule library and identified 21 compounds (Hits) that changed FRET by >3SD. 10 of these Hits reproducibly alter SERCA2a-PLB structure and function. One compound increases SERCA2a calcium affinity in cardiac membranes but not in skeletal, suggesting that the compound is acting specifically on the SERCA2a-PLB complex, as needed for a drug to mitigate deficient calcium transport in heart failure. The excellent assay quality and correlation between structural and functional assays validate this method for large-scale HTS campaigns. This approach offers a powerful pathway to drug discovery for a wide range of protein-protein interaction targets that were previously considered “undruggable”.
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Ceholski DK, Turnbull IC, Kong CW, Koplev S, Mayourian J, Gorski PA, Stillitano F, Skodras AA, Nonnenmacher M, Cohen N, Björkegren JLM, Stroik DR, Cornea RL, Thomas DD, Li RA, Costa KD, Hajjar RJ. Functional and transcriptomic insights into pathogenesis of R9C phospholamban mutation using human induced pluripotent stem cell-derived cardiomyocytes. J Mol Cell Cardiol 2018; 119:147-154. [PMID: 29752948 DOI: 10.1016/j.yjmcc.2018.05.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 05/07/2018] [Accepted: 05/08/2018] [Indexed: 12/27/2022]
Abstract
Dilated cardiomyopathy (DCM) can be caused by mutations in the cardiac protein phospholamban (PLN). We used CRISPR/Cas9 to insert the R9C PLN mutation at its endogenous locus into a human induced pluripotent stem cell (hiPSC) line from an individual with no cardiovascular disease. R9C PLN hiPSC-CMs display a blunted β-agonist response and defective calcium handling. In 3D human engineered cardiac tissues (hECTs), a blunted lusitropic response to β-adrenergic stimulation was observed with R9C PLN. hiPSC-CMs harboring the R9C PLN mutation showed activation of a hypertrophic phenotype, as evidenced by expression of hypertrophic markers and increased cell size and capacitance of cardiomyocytes. RNA-seq suggests that R9C PLN results in an altered metabolic state and profibrotic signaling, which was confirmed by gene expression analysis and picrosirius staining of R9C PLN hECTs. The expression of several miRNAs involved in fibrosis, hypertrophy, and cardiac metabolism were also perturbed in R9C PLN hiPSC-CMs. This study contributes to better understanding of the pathogenic mechanisms of the hereditary R9C PLN mutation in the context of human cardiomyocytes.
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Affiliation(s)
- Delaine K Ceholski
- Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - Irene C Turnbull
- Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - Chi-Wing Kong
- Department of Paediatrics and Adolescent Medicine, Hong Kong University, Pokfulam, Hong Kong
| | - Simon Koplev
- Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Joshua Mayourian
- Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - Przemek A Gorski
- Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - Francesca Stillitano
- Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - Angelos A Skodras
- Microscopy Core, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Mathieu Nonnenmacher
- Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - Ninette Cohen
- Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Johan L M Björkegren
- Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Daniel R Stroik
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, United States
| | - Razvan L Cornea
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, United States
| | - David D Thomas
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, United States
| | - Ronald A Li
- Department of Paediatrics and Adolescent Medicine, Hong Kong University, Pokfulam, Hong Kong; Ming Wai Lau Centre for Reparative Medicine, Karolinska Institutet, Solna SE-171, Sweden
| | - Kevin D Costa
- Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - Roger J Hajjar
- Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States.
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