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Lohanadan K, Assent M, Linnemann A, Schuld J, Heukamp LC, Krause K, Vorgerd M, Reimann J, Schänzer A, Kirfel G, Fürst DO, Van der Ven PFM. Synaptopodin-2 Isoforms Have Specific Binding Partners and Display Distinct, Muscle Cell Type-Specific Expression Patterns. Cells 2023; 13:85. [PMID: 38201288 PMCID: PMC10778272 DOI: 10.3390/cells13010085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 12/18/2023] [Accepted: 12/28/2023] [Indexed: 01/12/2024] Open
Abstract
Synaptopodin-2 (SYNPO2) is a protein associated with the Z-disc in striated muscle cells. It interacts with α-actinin and filamin C, playing a role in Z-disc maintenance under stress by chaperone-assisted selective autophagy (CASA). In smooth muscle cells, SYNPO2 is a component of dense bodies. Furthermore, it has been proposed to play a role in tumor cell proliferation and metastasis in many different kinds of cancers. Alternative transcription start sites and alternative splicing predict the expression of six putative SYNPO2 isoforms differing by extended amino- and/or carboxy-termini. Our analyses at mRNA and protein levels revealed differential expression of SYNPO2 isoforms in cardiac, skeletal and smooth muscle cells. We identified synemin, an intermediate filament protein, as a novel binding partner of the PDZ-domain in the amino-terminal extension of the isoforms mainly expressed in cardiac and smooth muscle cells, and demonstrated colocalization of SYNPO2 and synemin in both cell types. A carboxy-terminal extension, mainly expressed in smooth muscle cells, is sufficient for association with dense bodies and interacts with α-actinin. SYNPO2 therefore represents an additional and novel link between intermediate filaments and the Z-discs in cardiomyocytes and dense bodies in smooth muscle cells, respectively. In pathological skeletal muscle samples, we identified SYNPO2 in the central and intermediate zones of target fibers of patients with neurogenic muscular atrophy, and in nemaline bodies. Our findings help to understand distinct functions of individual SYNPO2 isoforms in different muscle tissues, but also in tumor pathology.
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Affiliation(s)
| | - Marvin Assent
- Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany
| | - Anja Linnemann
- Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany
| | - Julia Schuld
- Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany
| | - Lukas C. Heukamp
- Department of Pathology, University Hospital Bonn, 53127 Bonn, Germany
| | - Karsten Krause
- Department of Neurology, Heimer Institute for Muscle Research, University Hospital Bergmannsheil, Ruhr-University Bochum, 44789 Bochum, Germany
| | - Matthias Vorgerd
- Department of Neurology, Heimer Institute for Muscle Research, University Hospital Bergmannsheil, Ruhr-University Bochum, 44789 Bochum, Germany
| | - Jens Reimann
- Department of Neurology, Neuromuscular Diseases Section, University Hospital Bonn, 53127 Bonn, Germany
| | - Anne Schänzer
- Institute of Neuropathology, Justus-Liebig-University Giessen, 35392 Giessen, Germany
| | - Gregor Kirfel
- Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany
| | - Dieter O. Fürst
- Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany
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Sun B, Kekenes-Huskey PM. Myofilament-associated proteins with intrinsic disorder (MAPIDs) and their resolution by computational modeling. Q Rev Biophys 2023; 56:e2. [PMID: 36628457 PMCID: PMC11070111 DOI: 10.1017/s003358352300001x] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The cardiac sarcomere is a cellular structure in the heart that enables muscle cells to contract. Dozens of proteins belong to the cardiac sarcomere, which work in tandem to generate force and adapt to demands on cardiac output. Intriguingly, the majority of these proteins have significant intrinsic disorder that contributes to their functions, yet the biophysics of these intrinsically disordered regions (IDRs) have been characterized in limited detail. In this review, we first enumerate these myofilament-associated proteins with intrinsic disorder (MAPIDs) and recent biophysical studies to characterize their IDRs. We secondly summarize the biophysics governing IDR properties and the state-of-the-art in computational tools toward MAPID identification and characterization of their conformation ensembles. We conclude with an overview of future computational approaches toward broadening the understanding of intrinsic disorder in the cardiac sarcomere.
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Affiliation(s)
- Bin Sun
- Research Center for Pharmacoinformatics (The State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), Department of Medicinal Chemistry and Natural Medicine Chemistry, College of Pharmacy, Harbin Medical University, Harbin 150081, China
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3
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Schöck F, González-Morales N. The insect perspective on Z-disc structure and biology. J Cell Sci 2022; 135:277280. [PMID: 36226637 DOI: 10.1242/jcs.260179] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Myofibrils are the intracellular structures formed by actin and myosin filaments. They are paracrystalline contractile cables with unusually well-defined dimensions. The sliding of actin past myosin filaments powers contractions, and the entire system is held in place by a structure called the Z-disc, which anchors the actin filaments. Myosin filaments, in turn, are anchored to another structure called the M-line. Most of the complex architecture of myofibrils can be reduced to studying the Z-disc, and recently, important advances regarding the arrangement and function of Z-discs in insects have been published. On a very small scale, we have detailed protein structure information. At the medium scale, we have cryo-electron microscopy maps, super-resolution microscopy and protein-protein interaction networks, while at the functional scale, phenotypic data are available from precise genetic manipulations. All these data aim to answer how the Z-disc works and how it is assembled. Here, we summarize recent data from insects and explore how it fits into our view of the Z-disc, myofibrils and, ultimately, muscles.
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Affiliation(s)
- Frieder Schöck
- Department of Biology, McGill University, Montreal, Quebec, H3A 1B1, Canada
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4
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Mao Y, Schneider R, van der Ven PFM, Assent M, Lohanadan K, Klämbt V, Buerger F, Kitzler TM, Deutsch K, Nakayama M, Majmundar AJ, Mann N, Hermle T, Onuchic-Whitford AC, Zhou W, Margam NN, Duncan R, Marquez J, Khokha M, Fathy HM, Kari JA, El Desoky S, Eid LA, Awad HS, Al-Saffar M, Mane S, Lifton RP, Fürst DO, Shril S, Hildebrandt F. Recessive Mutations in SYNPO2 as a Candidate of Monogenic Nephrotic Syndrome. Kidney Int Rep 2020; 6:472-483. [PMID: 33615072 PMCID: PMC7879128 DOI: 10.1016/j.ekir.2020.10.040] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2020] [Revised: 10/10/2020] [Accepted: 10/27/2020] [Indexed: 12/28/2022] Open
Abstract
Introduction Most of the approximately 60 genes that if mutated cause steroid-resistant nephrotic syndrome (SRNS) are highly expressed in the glomerular podocyte, rendering SRNS a “podocytopathy.” Methods We performed whole-exome sequencing (WES) in 1200 nephrotic syndrome (NS) patients. Results We discovered homozygous truncating and homozygous missense mutation in SYNPO2 (synaptopodin-2) (p.Lys1124∗ and p.Ala1134Thr) in 2 patients with childhood-onset NS. We found SYNPO2 expression in both podocytes and mesangial cells; however, notably, immunofluorescence staining of adult human and rat kidney cryosections indicated that SYNPO2 is localized mainly in mesangial cells. Subcellular localization studies reveal that in these cells SYNPO2 partially co-localizes with α-actinin and filamin A−containing F-actin filaments. Upon transfection in mesangial cells or podocytes, EGFP-SYNPO2 co-localized with α-actinin-4, which gene is mutated in autosomal dominant SRNS in humans. SYNPO2 overexpression increases mesangial cell migration rate (MMR), whereas shRNA knockdown reduces MMR. Decreased MMR was rescued by transfection of wild-type mouse Synpo2 cDNA but only partially by cDNA representing mutations from the NS patients. The increased mesangial cell migration rate (MMR) by SYNPO2 overexpression was inhibited by ARP complex inhibitor CK666. SYNPO2 shRNA knockdown in podocytes decreased active Rac1, which was rescued by transfection of wild-type SYNPO2 cDNA but not by cDNA representing any of the 2 mutant variants. Conclusion We show that SYNPO2 variants may lead to Rac1-ARP3 dysregulation, and may play a role in the pathogenesis of nephrotic syndrome.
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Affiliation(s)
- Youying Mao
- Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA.,Department of Nephrology, Shanghai Children's Medical Center, Shanhai Jiaotong University, Shanghai, China
| | - Ronen Schneider
- Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Peter F M van der Ven
- Institute for Cell Biology, Department of Molecular Cell Biology, University of Bonn, Bonn, Germany
| | - Marvin Assent
- Institute for Cell Biology, Department of Molecular Cell Biology, University of Bonn, Bonn, Germany
| | - Keerthika Lohanadan
- Institute for Cell Biology, Department of Molecular Cell Biology, University of Bonn, Bonn, Germany
| | - Verena Klämbt
- Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Florian Buerger
- Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Thomas M Kitzler
- Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Konstantin Deutsch
- Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Makiko Nakayama
- Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Amar J Majmundar
- Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Nina Mann
- Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Tobias Hermle
- Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Ana C Onuchic-Whitford
- Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA.,Renal Division, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Wei Zhou
- Department of Nephrology, Shanghai Children's Medical Center, Shanhai Jiaotong University, Shanghai, China
| | | | - Roy Duncan
- Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Jonathan Marquez
- Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Mustafa Khokha
- Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Hanan M Fathy
- Department of Pediatrics, Alexandria Faculty of medicine, Alexandria University, Alexandria, Egypt
| | - Jameela A Kari
- Department of Pediatrics, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia.,Pediatric Nephrology Center of Excellence, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia
| | - Sherif El Desoky
- Department of Pediatrics, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia.,Pediatric Nephrology Center of Excellence, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia
| | - Loai A Eid
- Pediatric Nephrology Department, Dubai Kidney Center of Excellence, Dubai Hospital, Dubai, United Arab Emirates
| | - Hazem Subhi Awad
- Pediatric Nephrology Department, Dubai Kidney Center of Excellence, Dubai Hospital, Dubai, United Arab Emirates
| | - Muna Al-Saffar
- Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA.,United Arab Emirates University, Abu Dhabi, United Arab Emirates
| | - Shrikant Mane
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Richard P Lifton
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut, USA.,Howard Hughes Medical Institute, Chevy Chase, Maryland, USA
| | - Dieter O Fürst
- Institute for Cell Biology, Department of Molecular Cell Biology, University of Bonn, Bonn, Germany
| | - Shirlee Shril
- Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Friedhelm Hildebrandt
- Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
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5
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Moreno LA, Omidi M, Wurlitzer M, Luthringer B, Helmholz H, Schluter H, Willumeit-Romer R, Fugenschuh A. Understanding Protein Networks Using Vester's Sensitivity Model. IEEE/ACM TRANSACTIONS ON COMPUTATIONAL BIOLOGY AND BIOINFORMATICS 2020; 17:1440-1450. [PMID: 30530336 DOI: 10.1109/tcbb.2018.2885757] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Magnesium-based biomaterials belong to the third generation of biomaterials that are also bioactive. These smart materials combine bioactivity and biodegradability, and elicit specific cellular responses at the molecular level. In fact, osteoinductive properties have been observed in mesenchymal stem cells in the presence of Magnesium. The mechanistic understanding of the physiological effects however, remains a difficult task as Mg is involved in a multitude of biological reactions. The study of protein interactions may shed light on the molecular processes in Mg-stimulated cells, therefore, suitable data mining tools are required to analyze the large amount data generated via proteomics. Protein compositions over time between two conditions (human mesenchymal stem cells cultured with and without Mg degradation products) were analyzed using Vester's Sensitivity Model. Proteins whose dynamics significantly change from one setup to the other were classified into four categories: passive, active, critical, and buffering according to their regulatory activity. In this work, we demonstrated the use of Vester's Sensitivity Model as an appropriate data mining tool. Protein network analyses highlighted the primary role of Mg-based implant degradation on cell metabolism without deleterious effect on cell viability. Furthermore, key proteins involved in calcium-dependant cellular activities were emphasized leading to further studies.
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6
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Gao J, Zhang HP, Sun YH, Guo WZ, Li J, Tang HW, Guo DF, Zhang JK, Shi XY, Yu DS, Zhang XD, Wen PH, Shi JH, Zhang SJ. Synaptopodin-2 promotes hepatocellular carcinoma metastasis via calcineurin-induced nuclear-cytoplasmic translocation. Cancer Lett 2020; 482:8-18. [PMID: 32278815 DOI: 10.1016/j.canlet.2020.04.005] [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: 02/24/2020] [Revised: 04/05/2020] [Accepted: 04/06/2020] [Indexed: 12/14/2022]
Abstract
Hepatocellular carcinoma (HCC), a type of malignant liver tumor, has a grim prognosis. As a functional protein, synaptopodin-2 (SYNPO2) has been associated with malignancy; however, the expression profile and function of SYNPO2 in HCC remains unknown. Herein, we revealed that SYNPO2 was transcriptionally downregulated in HCC tissues from both The Cancer Genome Atlas cohort and our cohort, and was also decreased at the translational level as determined by western blotting and immunohistochemical staining. Furthermore, reduced SYNPO2 expression correlated significantly with short overall survival and recurrence free survival of HCC patients. Restoring SYNPO2 expression inhibited the proliferation and aggressiveness of hepatocarcinoma cells. Mechanistically, increasing the ratio of cytoplasmic SYNPO2 to nuclear SYNPO2 was positively associated with recurrence rate in HCC patients; calcineurin (CaN) activity positively correlated with cytoplasmic SYNPO2 levels in HCC tissues; and nuclear-cytoplasmic translocation of SYNPO2 was induced by CaN to facilitate metastasis of HCC through assembly of peripheral actin bundles. In short, our findings uncover a novel role of SYNPO2 in HCC metastasis via the CaN/SYNPO2/F-actin axis, and indicate that SYNPO2 may serve as a possible prognostic marker and novel therapeutic target.
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Affiliation(s)
- Jie Gao
- Department of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan Province, 450052, China; Henan Key Laboratory of Digestive Organ Transplantation, Zhengzhou, Henan Province, 450052, China; Open and Key Laboratory of Hepatobiliary & Pancreatic Surgery and Digestive Organ Transplantation at Henan Universities, Zhengzhou, Henan Province, 450052, China
| | - Hua-Peng Zhang
- Department of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan Province, 450052, China; Henan Key Laboratory of Digestive Organ Transplantation, Zhengzhou, Henan Province, 450052, China; Open and Key Laboratory of Hepatobiliary & Pancreatic Surgery and Digestive Organ Transplantation at Henan Universities, Zhengzhou, Henan Province, 450052, China
| | - Yao-Hui Sun
- Department of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan Province, 450052, China; Henan Key Laboratory of Digestive Organ Transplantation, Zhengzhou, Henan Province, 450052, China; Open and Key Laboratory of Hepatobiliary & Pancreatic Surgery and Digestive Organ Transplantation at Henan Universities, Zhengzhou, Henan Province, 450052, China
| | - Wen-Zhi Guo
- Department of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan Province, 450052, China; Henan Key Laboratory of Digestive Organ Transplantation, Zhengzhou, Henan Province, 450052, China; Open and Key Laboratory of Hepatobiliary & Pancreatic Surgery and Digestive Organ Transplantation at Henan Universities, Zhengzhou, Henan Province, 450052, China
| | - Jie Li
- Department of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan Province, 450052, China; Henan Key Laboratory of Digestive Organ Transplantation, Zhengzhou, Henan Province, 450052, China; Open and Key Laboratory of Hepatobiliary & Pancreatic Surgery and Digestive Organ Transplantation at Henan Universities, Zhengzhou, Henan Province, 450052, China
| | - Hong-Wei Tang
- Department of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan Province, 450052, China; Henan Key Laboratory of Digestive Organ Transplantation, Zhengzhou, Henan Province, 450052, China; Open and Key Laboratory of Hepatobiliary & Pancreatic Surgery and Digestive Organ Transplantation at Henan Universities, Zhengzhou, Henan Province, 450052, China
| | - Dan-Feng Guo
- Department of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan Province, 450052, China; Henan Key Laboratory of Digestive Organ Transplantation, Zhengzhou, Henan Province, 450052, China; Open and Key Laboratory of Hepatobiliary & Pancreatic Surgery and Digestive Organ Transplantation at Henan Universities, Zhengzhou, Henan Province, 450052, China
| | - Jia-Kai Zhang
- Department of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan Province, 450052, China; Henan Key Laboratory of Digestive Organ Transplantation, Zhengzhou, Henan Province, 450052, China; Open and Key Laboratory of Hepatobiliary & Pancreatic Surgery and Digestive Organ Transplantation at Henan Universities, Zhengzhou, Henan Province, 450052, China
| | - Xiao-Yi Shi
- Department of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan Province, 450052, China; Henan Key Laboratory of Digestive Organ Transplantation, Zhengzhou, Henan Province, 450052, China; Open and Key Laboratory of Hepatobiliary & Pancreatic Surgery and Digestive Organ Transplantation at Henan Universities, Zhengzhou, Henan Province, 450052, China
| | - Dong-Sheng Yu
- Department of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan Province, 450052, China; Henan Key Laboratory of Digestive Organ Transplantation, Zhengzhou, Henan Province, 450052, China; Open and Key Laboratory of Hepatobiliary & Pancreatic Surgery and Digestive Organ Transplantation at Henan Universities, Zhengzhou, Henan Province, 450052, China
| | - Xiao-Dan Zhang
- Department of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan Province, 450052, China; Henan Key Laboratory of Digestive Organ Transplantation, Zhengzhou, Henan Province, 450052, China; Open and Key Laboratory of Hepatobiliary & Pancreatic Surgery and Digestive Organ Transplantation at Henan Universities, Zhengzhou, Henan Province, 450052, China
| | - Pei-Hao Wen
- Department of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan Province, 450052, China; Henan Key Laboratory of Digestive Organ Transplantation, Zhengzhou, Henan Province, 450052, China; Open and Key Laboratory of Hepatobiliary & Pancreatic Surgery and Digestive Organ Transplantation at Henan Universities, Zhengzhou, Henan Province, 450052, China
| | - Jia-Hua Shi
- Department of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan Province, 450052, China; Henan Key Laboratory of Digestive Organ Transplantation, Zhengzhou, Henan Province, 450052, China; Open and Key Laboratory of Hepatobiliary & Pancreatic Surgery and Digestive Organ Transplantation at Henan Universities, Zhengzhou, Henan Province, 450052, China
| | - Shui-Jun Zhang
- Department of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan Province, 450052, China; Henan Key Laboratory of Digestive Organ Transplantation, Zhengzhou, Henan Province, 450052, China; Open and Key Laboratory of Hepatobiliary & Pancreatic Surgery and Digestive Organ Transplantation at Henan Universities, Zhengzhou, Henan Province, 450052, China.
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7
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Prill K, Dawson JF. Assembly and Maintenance of Sarcomere Thin Filaments and Associated Diseases. Int J Mol Sci 2020; 21:E542. [PMID: 31952119 PMCID: PMC7013991 DOI: 10.3390/ijms21020542] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 01/06/2020] [Accepted: 01/12/2020] [Indexed: 12/22/2022] Open
Abstract
Sarcomere assembly and maintenance are essential physiological processes required for cardiac and skeletal muscle function and organism mobility. Over decades of research, components of the sarcomere and factors involved in the formation and maintenance of this contractile unit have been identified. Although we have a general understanding of sarcomere assembly and maintenance, much less is known about the development of the thin filaments and associated factors within the sarcomere. In the last decade, advancements in medical intervention and genome sequencing have uncovered patients with novel mutations in sarcomere thin filaments. Pairing this sequencing with reverse genetics and the ability to generate patient avatars in model organisms has begun to deepen our understanding of sarcomere thin filament development. In this review, we provide a summary of recent findings regarding sarcomere assembly, maintenance, and disease with respect to thin filaments, building on the previous knowledge in the field. We highlight debated and unknown areas within these processes to clearly define open research questions.
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Affiliation(s)
| | - John F. Dawson
- Centre for Cardiovascular Investigations, Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada;
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8
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Reimann L, Wiese H, Leber Y, Schwäble AN, Fricke AL, Rohland A, Knapp B, Peikert CD, Drepper F, van der Ven PFM, Radziwill G, Fürst DO, Warscheid B. Myofibrillar Z-discs Are a Protein Phosphorylation Hot Spot with Protein Kinase C (PKCα) Modulating Protein Dynamics. Mol Cell Proteomics 2016; 16:346-367. [PMID: 28028127 DOI: 10.1074/mcp.m116.065425] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Indexed: 11/06/2022] Open
Abstract
The Z-disc is a protein-rich structure critically important for the development and integrity of myofibrils, which are the contractile organelles of cross-striated muscle cells. We here used mouse C2C12 myoblast, which were differentiated into myotubes, followed by electrical pulse stimulation (EPS) to generate contracting myotubes comprising mature Z-discs. Using a quantitative proteomics approach, we found significant changes in the relative abundance of 387 proteins in myoblasts versus differentiated myotubes, reflecting the drastic phenotypic conversion of these cells during myogenesis. Interestingly, EPS of differentiated myotubes to induce Z-disc assembly and maturation resulted in increased levels of proteins involved in ATP synthesis, presumably to fulfill the higher energy demand of contracting myotubes. Because an important role of the Z-disc for signal integration and transduction was recently suggested, its precise phosphorylation landscape further warranted in-depth analysis. We therefore established, by global phosphoproteomics of EPS-treated contracting myotubes, a comprehensive site-resolved protein phosphorylation map of the Z-disc and found that it is a phosphorylation hotspot in skeletal myocytes, underscoring its functions in signaling and disease-related processes. In an illustrative fashion, we analyzed the actin-binding multiadaptor protein filamin C (FLNc), which is essential for Z-disc assembly and maintenance, and found that PKCα phosphorylation at distinct serine residues in its hinge 2 region prevents its cleavage at an adjacent tyrosine residue by calpain 1. Fluorescence recovery after photobleaching experiments indicated that this phosphorylation modulates FLNc dynamics. Moreover, FLNc lacking the cleaved Ig-like domain 24 exhibited remarkably fast kinetics and exceedingly high mobility. Our data set provides research community resource for further identification of kinase-mediated changes in myofibrillar protein interactions, kinetics, and mobility that will greatly advance our understanding of Z-disc dynamics and signaling.
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Affiliation(s)
- Lena Reimann
- From the ‡Department of Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Heike Wiese
- From the ‡Department of Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Yvonne Leber
- ¶Department of Molecular Cell Biology, Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany
| | - Anja N Schwäble
- From the ‡Department of Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Anna L Fricke
- From the ‡Department of Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Anne Rohland
- ¶Department of Molecular Cell Biology, Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany
| | - Bettina Knapp
- From the ‡Department of Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Christian D Peikert
- From the ‡Department of Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Friedel Drepper
- From the ‡Department of Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Peter F M van der Ven
- ¶Department of Molecular Cell Biology, Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany
| | - Gerald Radziwill
- From the ‡Department of Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany.,§BIOSS Centre for Biological Signalling Studies, University of Freiburg
| | - Dieter O Fürst
- ¶Department of Molecular Cell Biology, Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany
| | - Bettina Warscheid
- From the ‡Department of Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany; .,§BIOSS Centre for Biological Signalling Studies, University of Freiburg
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9
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Kai F, Fawcett JP, Duncan R. Synaptopodin-2 induces assembly of peripheral actin bundles and immature focal adhesions to promote lamellipodia formation and prostate cancer cell migration. Oncotarget 2016; 6:11162-74. [PMID: 25883213 PMCID: PMC4484447 DOI: 10.18632/oncotarget.3578] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 02/10/2015] [Indexed: 01/02/2023] Open
Abstract
Synaptopodin-2 (Synpo2), an actin-binding protein and invasive cancer biomarker, induces formation of complex stress fiber networks in the cell body and promotes PC3 prostate cancer cell migration in response to serum stimulation. The role of these actin networks in enhanced cancer cell migration is unknown. Using time-course analysis and live cell imaging of mock- and Synpo2-transduced PC3 cells, we now show that Synpo2 induces assembly of actin fibers near the cell periphery and Arp2/3-dependent lamellipodia formation. Lamellipodia formed in a non-directional manner or repeatedly changed direction, explaining the enhanced chemokinetic activity of PC3 cells in response to serum stimulation. Myosin contraction promotes retrograde flow of the Synpo2-associated actin filaments at the leading edge and their merger with actin networks in the cell body. Enhanced PC3 cell migration correlates with Synpo2-induced formation of lamellipodia and immature focal adhesions (FAs), but is not dependent on myosin contraction or FA maturation. The previously reported correlation between Synpo2-induced stress fiber assembly and enhanced PC3 cell migration therefore reflects the role of Synpo2 as a newly identified regulator of actin bundle formation and nascent FA assembly near the leading cell edge.
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Affiliation(s)
- FuiBoon Kai
- Department of Microbiology & Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - James P Fawcett
- Department of Pharmacology, Dalhousie University, Halifax, Nova Scotia, Canada.,Department of Surgery, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Roy Duncan
- Department of Microbiology & Immunology, Dalhousie University, Halifax, Nova Scotia, Canada.,Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada.,Department of Pediatrics, Dalhousie University, Halifax, Nova Scotia, Canada
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Kooij V, Venkatraman V, Kirk JA, Ubaida-Mohien C, Graham DR, Faber MJ, Van Eyk JE. Identification of cardiac myofilament protein isoforms using multiple mass spectrometry based approaches. Proteomics Clin Appl 2015; 8:578-589. [PMID: 24974818 DOI: 10.1002/prca.201400039] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 05/30/2014] [Accepted: 06/24/2014] [Indexed: 02/01/2023]
Abstract
PURPOSE The identification of protein isoforms in complex biological samples is challenging. We, therefore, used an MS approach to unambiguously identify cardiac myofilament protein isoforms based on the observation of a tryptic peptide consisting of a sequence unique to a particular isoform. EXPERIMENTAL DESIGN Three different workflows were used to isolate and fractionate rat cardiac myofilament subproteomes. All fractions were analyzed on an LTQ-Orbitrap MS, proteins were identified using various search engines (MASCOT, X!Tandem, X!Tandem Kscore, and OMSSA) with results combined via PepArML Meta-Search engine, and a postsearch analysis was performed by MASPECTRAS. All MS data have been deposited in the ProteomeXchange with identifier PXD000874 (http://proteomecentral.proteomexchange.org/dataset/PXD000874). RESULTS The combination of multiple workflows and search engines resulted in a larger number of nonredundant proteins identified than with individual methods. A total of 102 myofilament annotated proteins were observed overlapping in two or three of the workflows. Literature search for myofilament presence with manual validation of the MS spectra was carried out for unambiguous identification: ten cardiac myofilament and 17 cardiac myofilament-associated proteins were identified with 39 isoforms and subisoforms. CONCLUSION AND CLINICAL RELEVANCE We have identified multiple isoforms of myofilament proteins that are present in cardiac tissue using unique tryptic peptides. Changes in distribution of these protein isoforms under pathological conditions could ultimately allow for clinical diagnostics or as therapeutic targets.
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Affiliation(s)
- Viola Kooij
- Department of medicine, Division of Cardiology, The Johns Hopkins University, Baltimore, USA
| | - Vidya Venkatraman
- Department of medicine, Division of Cardiology, The Johns Hopkins University, Baltimore, USA.,Advanced Clinical Biosystems Research Institute, Heart Institute and Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, USA
| | - Jonathan A Kirk
- Department of medicine, Division of Cardiology, The Johns Hopkins University, Baltimore, USA
| | - Ceereena Ubaida-Mohien
- Department of Molecular and Comparative Pathobiology, The Johns Hopkins University, Baltimore, MD, USA
| | - David R Graham
- Department of medicine, Division of Cardiology, The Johns Hopkins University, Baltimore, USA.,Department of Molecular and Comparative Pathobiology, The Johns Hopkins University, Baltimore, MD, USA
| | - Matthijs J Faber
- Erasmus MC-Sophia, Department of Pediatrics, Division of Pediatric Cardiology, Rotterdam, The Netherlands
| | - Jennifer E Van Eyk
- Department of medicine, Division of Cardiology, The Johns Hopkins University, Baltimore, USA.,Advanced Clinical Biosystems Research Institute, Heart Institute and Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, USA
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Kingsbury NL, Renegar RH, Chalovich JM. Avian synaptopodin 2 (fesselin) stabilizes myosin filaments and actomyosin in the presence of ATP. Biochemistry 2013; 52:7641-7. [PMID: 24083890 DOI: 10.1021/bi401013g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Smooth muscle cells maintain filaments of actin and myosin in the presence of ATP, although dephosphorylated myosin filaments and actin-myosin interactions are unstable under those conditions in vitro. Several proteins that stabilize myosin filaments and that stabilize actin-myosin interactions have been identified. Fesselin or synaptopodin 2 appears to be another such protein. Rapid kinetic measurements and electron microscopy demonstrated that fesselin, isolated from turkey gizzard muscle, reduced the rate of dissociation of myosin filaments. Addition of fesselin increased both the length and thickness of myosin filaments. The rate of detachment of myosin, but not heavy meromyosin, from actin was also greatly reduced by fesselin. Data from this study suggest that fesselin stabilizes myosin filaments and tethers myosin to actin. These results support the view that one role of fesselin is to organize contractile units of myosin and actin.
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Affiliation(s)
- Nathanial L Kingsbury
- Department of Biochemistry and Molecular Biology, Brody School of Medicine at East Carolina University , 600 Moye Boulevard, Greenville, North Carolina 27834-4300, United States
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Kai F, Duncan R. Prostate cancer cell migration induced by myopodin isoforms is associated with formation of morphologically and biochemically distinct actin networks. FASEB J 2013; 27:5046-58. [PMID: 24005909 DOI: 10.1096/fj.13-231571] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Myopodin is an actin-binding protein that promotes cancer cell migration in response to serum stimulation and is associated with invasive tumor development. To determine whether enhanced migration reflects changes in actin cytoskeleton remodeling, fluorescence confocal microscopy was used to examine the composition and morphology of filamentous actin structures in mock-transduced cells vs. stably transduced PC3 cells expressing human myopodin isoforms, and the chemokinetic response of cells was quantified using transwell assays. The same approaches were used to analyze the effects of external migration stimuli, actin polymerization inhibitors or deletion of the isoform-specific amino- and/or carboxy termini on cell migration and actin bundle formation. Results indicate that the termini of the myopodin isoforms differentially alter the formation of morphologically distinct F-actin networks that also differ in their myosin and myopodin staining patterns. Furthermore, enhanced cell migration was reduced by >50% when actin bundle formation was impaired by myopodin-truncation, low concentrations of an actin polymerization inhibitor, or in the absence of an external migration stimulus. Human myopodin isoforms are therefore potent regulators of stress fiber formation, inducing the formation of biochemically and morphologically distinct F-actin networks in the cell body whose presence directly correlates with increased cell migration.
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Affiliation(s)
- FuiBoon Kai
- 1Department of Microbiology and Immunology, Tupper Medical Bldg., 5850 College St., PO Box 15000, Dalhousie University, Halifax, NS, Canada, B3H 4R2.
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Schroeter MM, Orlova A, Egelman EH, Beall B, Chalovich JM. Organization of F-actin by Fesselin (avian smooth muscle synaptopodin 2). Biochemistry 2013; 52:4955-61. [PMID: 23789719 PMCID: PMC3842371 DOI: 10.1021/bi4005254] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Fesselin or avian synaptopodin 2 is a member of the synaptopodin family of actin binding proteins. Fesselin promotes G-actin polymerization and the formation of large actin complexes that can be collected by low-speed centrifugation. Because of the potential role of fesselin in some cancers and its effects on actin, we further investigated the effect of fesselin on actin. Fesselin initiated actin polymerization under a variety of conditions, including the virtual absence of salt. Actin filaments formed at low salt concentrations in the presence of fesselin were similar to filaments polymerized in the presence of 100 mM KCl. In both cases, the filaments were long and straight with a common orientation. Highly ordered actin bundles formed with increasing times of incubation. Blockers of actin growth at the barbed end (cytochalasin D and CapZ) did not prevent fesselin from polymerizing actin. Low concentrations of fesselin increased the critical concentration of actin. Both observations are consistent with preferential growth at the pointed end of actin filaments. These results indicate a role of fesselin in organizing cellular actin. These and other results indicate that fesselin is part of a cellular actin organizing center.
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Affiliation(s)
- Mechthild M. Schroeter
- Institute of Vegetative Physiology University of Cologne, Robert Koch Strasse 39, D-50931 Cologne, Germany Phone: +49-221-478-7855 Fax: +49-221-478-3538
| | - Albina Orlova
- Department of Biochemistry and Molecular Genetics University of Virginia Box 800733 Charlottesville, VA 22908-0733 Phone: 434-924-8210 Fax: 434-924-5069
| | - Edward H. Egelman
- Department of Biochemistry and Molecular Genetics University of Virginia Box 800733 Charlottesville, VA 22908-0733 Phone: 434-924-8210 Fax: 434-924-5069
| | - Brent Beall
- Department of Biotechnology Athens Technical College 800 US HWY 29N Athens, GA 30601 Phone: 706-227-5350 Fax: 706-425-3104
| | - Joseph M. Chalovich
- Department of Biochemistry & Molecular Biology Brody School of Medicine at East Carolina University 600 Moye Blvd. Greenville, NC 27834-4300, USA Phone: 252-744-2973
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