1
|
Zhou X, Duan J, Zhou W, Zhang A, Chen Q. Upregulated α-actinin-1 impairs endometrial epithelial cell adhesion by downregulating NEBL in recurrent implantation failure. iScience 2024; 27:109046. [PMID: 38384848 PMCID: PMC10879697 DOI: 10.1016/j.isci.2024.109046] [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] [Received: 05/25/2023] [Revised: 10/28/2023] [Accepted: 01/23/2024] [Indexed: 02/23/2024] Open
Abstract
Poor endometrial receptivity results in embryo implantation failure. Acquisition of endometrial receptivity involves substantial structural alterations in the cytoskeleton and plasma membrane of epithelial cells, which facilitate embryo adhesion. However, the underlying molecular mechanism remains largely unknown. In this study, we identified that α-actinin-1 (ACTN1) was significantly downregulated in the mid-secretory phase of the endometrium compared with other phases; however, ACTN1 significantly increased in women with recurrent implantation failure (RIF). In Ishikawa and human endometrial epithelial cells (HEECs), ACTN1 overexpression significantly decreased NEBL levels, enhanced F-actin fiber levels, and caused a notable impairment in blastocyst adhesion, which mimicked the process of embryo adhesion. However, NEBL overexpression notably restored adhesion. Moreover, NEBL expression was reduced in patients with RIF compared with that in controls. Finally, our data showed that ACTN1 upregulation impaired endometrial receptivity in women with RIF, possibly by regulating NEBL expression and subsequent cell-adhesion capability.
Collapse
Affiliation(s)
- Xiaowei Zhou
- Department of Obstetrics and Gynecology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jingru Duan
- Department of Obstetrics and Gynecology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Wenjie Zhou
- Department of Obstetrics and Gynecology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Aijun Zhang
- Department of Obstetrics and Gynecology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Qian Chen
- Department of Obstetrics and Gynecology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| |
Collapse
|
2
|
Zhao R, Liang Z, Chu J, Zheng Q, Zhao J, Tang S, Chen Q, Huang Y, Zhou X, Pan X. Downregulation of NEBL promotes migration and invasion of clear cell renal cell carcinoma by inducing epithelial-mesenchymal transition. Pathol Res Pract 2024; 254:155068. [PMID: 38215565 DOI: 10.1016/j.prp.2023.155068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Revised: 10/04/2023] [Accepted: 12/27/2023] [Indexed: 01/14/2024]
Abstract
As a member of the nebulin protein family and a structural protein of cytoskeleton, NEBL plays an important role in cardiac diseases. Recently, literature have reported the involvement of NEBL in the occurrence and development of various cancers except clear cell renal cell carcinoma (ccRCC). In this study, we found that mRNA and protein of NEBL are downregulated remarkably in ccRCC tissues based on both the TCGA database and clinical samples we collected. The areas under curve values of NEBL analyzed based on the TCGA database, qRT-PCR and IHC results were 0.9376, 0.9733 and 0.9807, respectively. The lower mRNA level of NEBL was associated with worse outcomes in ccRCC patients. When overexpressing NEBL in ccRCC cell lines, the proliferation, migration and invasion of ccRCC cells were suppressed significantly, suggesting a tumor suppressor role of NEBL. In addition, we identified that NEBL is closely related to epithelial-mesenchymal transition (EMT), thereby reducing the motility of ccRCC cells. Furthermore, the lower expression of NEBL was correlated with ccRCC patients with distant organ metastasis. In summary, we firstly described the aberrant expression of NEBL and revealed its tumor suppressor role in ccRCC. Our data support that NEBL could serve as a valuable diagnostic and prognostic biomarker in ccRCC, as well as a promising therapeutic target.
Collapse
Affiliation(s)
- Ran Zhao
- Life Science Institute, Guangxi Medical University, China; Key Laboratory of High-Incidence-Tumor Prevention & Treatment (Guangxi Medical University), Ministry of Education, Nanning, China
| | - Ziyuan Liang
- Life Science Institute, Guangxi Medical University, China; Key Laboratory of High-Incidence-Tumor Prevention & Treatment (Guangxi Medical University), Ministry of Education, Nanning, China
| | - Jiemei Chu
- Life Science Institute, Guangxi Medical University, China
| | - Qian Zheng
- Life Science Institute, Guangxi Medical University, China; Key Laboratory of High-Incidence-Tumor Prevention & Treatment (Guangxi Medical University), Ministry of Education, Nanning, China
| | - Jun Zhao
- Key Laboratory of High-Incidence-Tumor Prevention & Treatment (Guangxi Medical University), Ministry of Education, Nanning, China
| | - Shiyue Tang
- Key Laboratory of High-Incidence-Tumor Prevention & Treatment (Guangxi Medical University), Ministry of Education, Nanning, China
| | - Qiaoli Chen
- Key Laboratory of High-Incidence-Tumor Prevention & Treatment (Guangxi Medical University), Ministry of Education, Nanning, China
| | - Yiying Huang
- Key Laboratory of High-Incidence-Tumor Prevention & Treatment (Guangxi Medical University), Ministry of Education, Nanning, China
| | - Xiaoying Zhou
- Life Science Institute, Guangxi Medical University, China.
| | - Xinli Pan
- Guangxi Key Laboratory of Marine Natural Products and Combinatorial Biosynthesis Chemistry, Guangxi Academy of Sciences, China.
| |
Collapse
|
3
|
Coscarella IL, Landim-Vieira M, Rastegarpouyani H, Chase PB, Irianto J, Pinto JR. Nucleus Mechanosensing in Cardiomyocytes. Int J Mol Sci 2023; 24:13341. [PMID: 37686151 PMCID: PMC10487505 DOI: 10.3390/ijms241713341] [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: 07/14/2023] [Revised: 08/20/2023] [Accepted: 08/22/2023] [Indexed: 09/10/2023] Open
Abstract
Cardiac muscle contraction is distinct from the contraction of other muscle types. The heart continuously undergoes contraction-relaxation cycles throughout an animal's lifespan. It must respond to constantly varying physical and energetic burdens over the short term on a beat-to-beat basis and relies on different mechanisms over the long term. Muscle contractility is based on actin and myosin interactions that are regulated by cytoplasmic calcium ions. Genetic variants of sarcomeric proteins can lead to the pathophysiological development of cardiac dysfunction. The sarcomere is physically connected to other cytoskeletal components. Actin filaments, microtubules and desmin proteins are responsible for these interactions. Therefore, mechanical as well as biochemical signals from sarcomeric contractions are transmitted to and sensed by other parts of the cardiomyocyte, particularly the nucleus which can respond to these stimuli. Proteins anchored to the nuclear envelope display a broad response which remodels the structure of the nucleus. In this review, we examine the central aspects of mechanotransduction in the cardiomyocyte where the transmission of mechanical signals to the nucleus can result in changes in gene expression and nucleus morphology. The correlation of nucleus sensing and dysfunction of sarcomeric proteins may assist the understanding of a wide range of functional responses in the progress of cardiomyopathic diseases.
Collapse
Affiliation(s)
| | - Maicon Landim-Vieira
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL 32306, USA
| | - Hosna Rastegarpouyani
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA
- Institute for Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA
| | - Prescott Bryant Chase
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA
| | - Jerome Irianto
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL 32306, USA
| | - Jose Renato Pinto
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL 32306, USA
| |
Collapse
|
4
|
Noureddine M, Gehmlich K. Structural and signaling proteins in the Z-disk and their role in cardiomyopathies. Front Physiol 2023; 14:1143858. [PMID: 36935760 PMCID: PMC10017460 DOI: 10.3389/fphys.2023.1143858] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 02/21/2023] [Indexed: 03/06/2023] Open
Abstract
The sarcomere is the smallest functional unit of muscle contraction. It is delineated by a protein-rich structure known as the Z-disk, alternating with M-bands. The Z-disk anchors the actin-rich thin filaments and plays a crucial role in maintaining the mechanical stability of the cardiac muscle. A multitude of proteins interact with each other at the Z-disk and they regulate the mechanical properties of the thin filaments. Over the past 2 decades, the role of the Z-disk in cardiac muscle contraction has been assessed widely, however, the impact of genetic variants in Z-disk proteins has still not been fully elucidated. This review discusses the various Z-disk proteins (alpha-actinin, filamin C, titin, muscle LIM protein, telethonin, myopalladin, nebulette, and nexilin) and Z-disk-associated proteins (desmin, and obscurin) and their role in cardiac structural stability and intracellular signaling. This review further explores how genetic variants of Z-disk proteins are linked to inherited cardiac conditions termed cardiomyopathies.
Collapse
Affiliation(s)
- Maya Noureddine
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
- *Correspondence: Maya Noureddine, ; Katja Gehmlich,
| | - Katja Gehmlich
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
- Cardiovascular Medicine, Radcliffe Department of Medicine and British Heart Foundation Centre of Research Excellence Oxford, University of Oxford, Oxford, United Kingdom
- *Correspondence: Maya Noureddine, ; Katja Gehmlich,
| |
Collapse
|
5
|
Eriksson ANM, Rigaud C, Rokka A, Skaugen M, Lihavainen JH, Vehniäinen ER. Changes in cardiac proteome and metabolome following exposure to the PAHs retene and fluoranthene and their mixture in developing rainbow trout alevins. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 830:154846. [PMID: 35351515 DOI: 10.1016/j.scitotenv.2022.154846] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 03/11/2022] [Accepted: 03/23/2022] [Indexed: 06/14/2023]
Abstract
Exposure to polycyclic aromatic hydrocarbons (PAHs) is known to affect developing organisms. Utilization of different omics-based technologies and approaches could therefore provide a base for the discovery of novel mechanisms of PAH induced development of toxicity. To this aim, we investigated how exposure towards two PAHs with different toxicity mechanisms: retene (an aryl hydrocarbon receptor 2 (Ahr2) agonist), and fluoranthene (a weak Ahr2 agonist and cytochrome P450 inhibitor (Cyp1a)), either alone or as a mixture, affected the cardiac proteome and metabolome in newly hatched rainbow trout alevins (Oncorhynchus mykiss). In total, we identified 65 and 82 differently expressed proteins (DEPs) across all treatments compared to control (DMSO) after 7 and 14 days of exposure. Exposure to fluoranthene altered the expression of 11 and 19 proteins, retene 29 and 23, while the mixture affected 44 and 82 DEPs by Days 7 and 14, respectively. In contrast, only 5 significantly affected metabolites were identified. Pathway over-representation analysis identified exposure-specific activation of phase II metabolic processes, which were accompanied with exposure-specific body burden profiles. The proteomic data highlights that exposure to the mixture increased oxidative stress, altered iron metabolism and impaired coagulation capacity. Additionally, depletion of several mini-chromosome maintenance components, in combination with depletion of several intermediate filaments and microtubules, among alevins exposed to the mixture, suggests compromised cellular integrity and reduced rate of mitosis, whereby affecting heart growth and development. Furthermore, the combination of proteomic and metabolomic data indicates altered energy metabolism, as per amino acid catabolism among mixture exposed alevins; plausibly compensatory mechanisms as to counteract reduced absorption and consumption of yolk. When considered as a whole, proteomic and metabolomic data, in relation to apical effects on the whole organism, provides additional insight into PAH toxicity and the effects of exposure on heart structure and molecular processes.
Collapse
Affiliation(s)
- Andreas N M Eriksson
- Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35, FI-40014, Finland.
| | - Cyril Rigaud
- Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35, FI-40014, Finland.
| | - Anne Rokka
- Turku Proteomics Facility, Turku University, Tykistökatu 6, 20520 Turku, Finland.
| | - Morten Skaugen
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Campus Ås, Universitetstunet 3, 1430 Ås, Norway.
| | - Jenna H Lihavainen
- Umeå Plant Science Centre, Umeå University, KB. K3 (Fys. Bot.), Artedigränd 7, Fysiologisk botanik, UPSC, KB. K3 (B3.44.45) Umeå universitet, 901 87 Umeå, Sweden.
| | - Eeva-Riikka Vehniäinen
- Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35, FI-40014, Finland.
| |
Collapse
|
6
|
The Mechanisms of Thin Filament Assembly and Length Regulation in Muscles. Int J Mol Sci 2022; 23:ijms23105306. [PMID: 35628117 PMCID: PMC9140763 DOI: 10.3390/ijms23105306] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 05/05/2022] [Accepted: 05/06/2022] [Indexed: 02/01/2023] Open
Abstract
The actin containing tropomyosin and troponin decorated thin filaments form one of the crucial components of the contractile apparatus in muscles. The thin filaments are organized into densely packed lattices interdigitated with myosin-based thick filaments. The crossbridge interactions between these myofilaments drive muscle contraction, and the degree of myofilament overlap is a key factor of contractile force determination. As such, the optimal length of the thin filaments is critical for efficient activity, therefore, this parameter is precisely controlled according to the workload of a given muscle. Thin filament length is thought to be regulated by two major, but only partially understood mechanisms: it is set by (i) factors that mediate the assembly of filaments from monomers and catalyze their elongation, and (ii) by factors that specify their length and uniformity. Mutations affecting these factors can alter the length of thin filaments, and in human cases, many of them are linked to debilitating diseases such as nemaline myopathy and dilated cardiomyopathy.
Collapse
|
7
|
Bang ML, Bogomolovas J, Chen J. Understanding the molecular basis of cardiomyopathy. Am J Physiol Heart Circ Physiol 2022; 322:H181-H233. [PMID: 34797172 PMCID: PMC8759964 DOI: 10.1152/ajpheart.00562.2021] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 11/16/2021] [Accepted: 11/16/2021] [Indexed: 02/03/2023]
Abstract
Inherited cardiomyopathies are a major cause of mortality and morbidity worldwide and can be caused by mutations in a wide range of proteins located in different cellular compartments. The present review is based on Dr. Ju Chen's 2021 Robert M. Berne Distinguished Lectureship of the American Physiological Society Cardiovascular Section, in which he provided an overview of the current knowledge on the cardiomyopathy-associated proteins that have been studied in his laboratory. The review provides a general summary of the proteins in different compartments of cardiomyocytes associated with cardiomyopathies, with specific focus on the proteins that have been studied in Dr. Chen's laboratory.
Collapse
Affiliation(s)
- Marie-Louise Bang
- Institute of Genetic and Biomedical Research (IRGB), National Research Council (CNR), Milan Unit, Milan, Italy
- IRCCS Humanitas Research Hospital, Rozzano (Milan), Italy
| | - Julius Bogomolovas
- Division of Cardiovascular Medicine, Department of Medicine Cardiology, University of California, San Diego, La Jolla, California
| | - Ju Chen
- Division of Cardiovascular Medicine, Department of Medicine Cardiology, University of California, San Diego, La Jolla, California
| |
Collapse
|
8
|
Filomena MC, Yamamoto DL, Carullo P, Medvedev R, Ghisleni A, Piroddi N, Scellini B, Crispino R, D'Autilia F, Zhang J, Felicetta A, Nemska S, Serio S, Tesi C, Catalucci D, Linke WA, Polishchuk R, Poggesi C, Gautel M, Bang ML. Myopalladin knockout mice develop cardiac dilation and show a maladaptive response to mechanical pressure overload. eLife 2021; 10:e58313. [PMID: 34558411 PMCID: PMC8547954 DOI: 10.7554/elife.58313] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 09/23/2021] [Indexed: 12/13/2022] Open
Abstract
Myopalladin (MYPN) is a striated muscle-specific immunoglobulin domain-containing protein located in the sarcomeric Z-line and I-band. MYPN gene mutations are causative for dilated (DCM), hypertrophic, and restrictive cardiomyopathy. In a yeast two-hybrid screening, MYPN was found to bind to titin in the Z-line, which was confirmed by microscale thermophoresis. Cardiac analyses of MYPN knockout (MKO) mice showed the development of mild cardiac dilation and systolic dysfunction, associated with decreased myofibrillar isometric tension generation and increased resting tension at longer sarcomere lengths. MKO mice exhibited a normal hypertrophic response to transaortic constriction (TAC), but rapidly developed severe cardiac dilation and systolic dysfunction, associated with fibrosis, increased fetal gene expression, higher intercalated disc fold amplitude, decreased calsequestrin-2 protein levels, and increased desmoplakin and SORBS2 protein levels. Cardiomyocyte analyses showed delayed Ca2+ release and reuptake in unstressed MKO mice as well as reduced Ca2+ spark amplitude post-TAC, suggesting that altered Ca2+ handling may contribute to the development of DCM in MKO mice.
Collapse
Affiliation(s)
- Maria Carmela Filomena
- Institute of Genetic and Biomedical Research (IRGB) - National Research Council (CNR), Milan unitMilanItaly
- IRCCS Humanitas Research HospitalMilanItaly
| | - Daniel L Yamamoto
- Institute of Genetic and Biomedical Research (IRGB) - National Research Council (CNR), Milan unitMilanItaly
| | - Pierluigi Carullo
- Institute of Genetic and Biomedical Research (IRGB) - National Research Council (CNR), Milan unitMilanItaly
- IRCCS Humanitas Research HospitalMilanItaly
| | - Roman Medvedev
- IRCCS Humanitas Research HospitalMilanItaly
- Department of Cardiac Surgery, University of VeronaVeronaItaly
| | - Andrea Ghisleni
- Randall Centre for Cell and Molecular Biophysics, King's College London BHF Centre of Research ExcellenceLondonUnited Kingdom
| | - Nicoletta Piroddi
- Department of Experimental and Clinical Medicine, University of FlorenceFlorenceItaly
| | - Beatrice Scellini
- Department of Experimental and Clinical Medicine, University of FlorenceFlorenceItaly
| | - Roberta Crispino
- Telethon Institute of Genetics and Medicine (TIGEM)PozzuoliItaly
| | | | - Jianlin Zhang
- Department of Medicine, University of California, San DiegoLa JollaUnited States
| | - Arianna Felicetta
- IRCCS Humanitas Research HospitalMilanItaly
- Humanitas UniversityPieve EmanueleItaly
| | | | | | - Chiara Tesi
- Department of Experimental and Clinical Medicine, University of FlorenceFlorenceItaly
| | | | - Wolfgang A Linke
- Institute of Physiology II, University of MuensterMuensterGermany
| | - Roman Polishchuk
- Telethon Institute of Genetics and Medicine (TIGEM)PozzuoliItaly
| | - Corrado Poggesi
- Department of Experimental and Clinical Medicine, University of FlorenceFlorenceItaly
| | - Mathias Gautel
- Randall Centre for Cell and Molecular Biophysics, King's College London BHF Centre of Research ExcellenceLondonUnited Kingdom
| | - Marie-Louise Bang
- Institute of Genetic and Biomedical Research (IRGB) - National Research Council (CNR), Milan unitMilanItaly
- IRCCS Humanitas Research HospitalMilanItaly
| |
Collapse
|
9
|
Axelsson E, Ljungvall I, Bhoumik P, Conn LB, Muren E, Ohlsson Å, Olsen LH, Engdahl K, Hagman R, Hanson J, Kryvokhyzha D, Pettersson M, Grenet O, Moggs J, Del Rio-Espinola A, Epe C, Taillon B, Tawari N, Mane S, Hawkins T, Hedhammar Å, Gruet P, Häggström J, Lindblad-Toh K. The genetic consequences of dog breed formation-Accumulation of deleterious genetic variation and fixation of mutations associated with myxomatous mitral valve disease in cavalier King Charles spaniels. PLoS Genet 2021; 17:e1009726. [PMID: 34473707 PMCID: PMC8412370 DOI: 10.1371/journal.pgen.1009726] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 07/20/2021] [Indexed: 02/07/2023] Open
Abstract
Selective breeding for desirable traits in strictly controlled populations has generated an extraordinary diversity in canine morphology and behaviour, but has also led to loss of genetic variation and random entrapment of disease alleles. As a consequence, specific diseases are now prevalent in certain breeds, but whether the recent breeding practice led to an overall increase in genetic load remains unclear. Here we generate whole genome sequencing (WGS) data from 20 dogs per breed from eight breeds and document a ~10% rise in the number of derived alleles per genome at evolutionarily conserved sites in the heavily bottlenecked cavalier King Charles spaniel breed (cKCs) relative to in most breeds studied here. Our finding represents the first clear indication of a relative increase in levels of deleterious genetic variation in a specific breed, arguing that recent breeding practices probably were associated with an accumulation of genetic load in dogs. We then use the WGS data to identify candidate risk alleles for the most common cause for veterinary care in cKCs–the heart disease myxomatous mitral valve disease (MMVD). We verify a potential link to MMVD for candidate variants near the heart specific NEBL gene in a dachshund population and show that two of the NEBL candidate variants have regulatory potential in heart-derived cell lines and are associated with reduced NEBL isoform nebulette expression in papillary muscle (but not in mitral valve, nor in left ventricular wall). Alleles linked to reduced nebulette expression may hence predispose cKCs and other breeds to MMVD via loss of papillary muscle integrity. As a consequence of selective breeding, specific disease-causing mutations have become more frequent in certain dog breeds. Whether the breeding practice also resulted in a general increase in the overall number of disease-causing mutations per dog genome is however not clear. To address this question, we compare the amount of harmful, potentially disease-causing, mutations in dogs from eight common breeds that have experienced varying degrees of intense selective breeding. We find that individuals belonging to the breed affected by the most intense breeding—cavalier King Charles spaniel (cKCs)—carry more harmful variants than other breeds, indicating that past breeding practices may have increased the overall levels of harmful genetic variation in dogs. The most common disease in cKCs is myxomatous mitral valve disease (MMVD). To identify variants linked to this disease we next characterize mutations that are common in cKCs, but rare in other breeds, and then investigate if these mutations can predict MMVD in dachshunds. We find that variants that regulate the expression of the gene NEBL in papillary muscles may increase the risk of the disease, indicating that loss of papillary muscle integrity could contribute to the development of MMVD.
Collapse
Affiliation(s)
- Erik Axelsson
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
- * E-mail:
| | - Ingrid Ljungvall
- Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Priyasma Bhoumik
- Translational Medicine, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Laura Bas Conn
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Eva Muren
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Åsa Ohlsson
- Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Lisbeth Høier Olsen
- Department of Veterinary and Animal Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Karolina Engdahl
- Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Ragnvi Hagman
- Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Jeanette Hanson
- Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Dmytro Kryvokhyzha
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Mats Pettersson
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Olivier Grenet
- Translational Medicine, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Jonathan Moggs
- Translational Medicine, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | | | - Christian Epe
- Elanco Animal Health, Greenfield, Indiana, United States of America
| | - Bruce Taillon
- Elanco Animal Health, Greenfield, Indiana, United States of America
| | - Nilesh Tawari
- Elanco Animal Health, Greenfield, Indiana, United States of America
| | - Shrinivas Mane
- Elanco Animal Health, Greenfield, Indiana, United States of America
| | - Troy Hawkins
- Elanco Animal Health, Greenfield, Indiana, United States of America
| | - Åke Hedhammar
- Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | | | - Jens Häggström
- Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Kerstin Lindblad-Toh
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
| |
Collapse
|
10
|
Vejandla RM, Orgil BO, Alberson NR, Li N, Munkhsaikhan U, Khuchua Z, Martherus R, Azeloglu EU, Xu F, Lu L, Towbin JA, Purevjav E. Deficiency in nebulin repeats of sarcomeric nebulette is detrimental for cardiomyocyte tolerance to exercise and biomechanical stress. Am J Physiol Heart Circ Physiol 2021; 320:H2130-H2146. [PMID: 33861145 DOI: 10.1152/ajpheart.00732.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The actin-binding sarcomeric nebulette (NEBL) protein provides efficient contractile flexibility via interaction with desmin intermediate filaments. NEBL gene mutations affecting the nebulin repeat (NR) domain are known to induce cardiomyopathy. The study aimed to explore the roles of NEBL in exercise and biomechanical stress response. We ablated exon3 encoding the first NR of Nebl and created global Neblex3-/ex3- knockout mice. Cardiac function, structure, and transcriptome were assessed before and after a 4-wk treadmill regimen. A Nebl-based exercise signaling network was constructed using systems genetics methods. H9C2 and neonatal rat cardiomyocytes (NRCs) expressing wild-type or mutant NEBL underwent cyclic mechanical strain. Neblex3-/ex3- mice demonstrated diastolic dysfunction with preserved systolic function at 6 mo of age. After treadmill running, 4-mo-old Neblex3-/ex3- mice developed concentric cardiac hypertrophy and left ventricular dilation compared with running Nebl+/+ and sedentary Neblex3-/ex3- mice. Disturbance of sarcomeric Z-disks and thin filaments architecture and disruption of intercalated disks and mitochondria were found in exercised Neblex3-/ex3- mice. A Nebl-based exercise signaling network included Csrp3, Des, Fbox32, Jup, Myh6, and Myh7. Disturbed expression of TM1, DES, JUP, β-catenin, MLP, α-actinin2, and vinculin proteins was demonstrated. In H9C2 cells, NEBL was recruited into focal adhesions at 24-h poststrain and redistributed along with F-actin at 72-h poststrain, suggesting time-dependent redistribution of NEBL in response to strain. NEBL mutations cause desmin disorganization in NRCs upon stretch. We conclude that Nebl's NR ablation causes disturbed sarcomere, Z-disks, and desmin organization, and prevents NEBL redistribution to focal adhesions in cardiomyocytes, weakening cardiac tolerance to biomechanical stress.NEW & NOTEWORTHY We demonstrate that ablation of first nebulin-repeats of sarcomeric nebulette (Nebl) causes diastolic dysfunction in Neblex3-/ex3- mice. Exercise-induced development of diastolic dysfunction, cardiac hypertrophy and ventricular dilation in knockouts. This was associated with sarcomere disturbance, intercalated disks disruption, and mitochondrial distortion upon stress and altered expression of genes involved in Nebl-based stress network. We demonstrate that G202R and A592 mutations alter actin and desmin expression causing disorganization of desmin filaments upon cyclic strain.
Collapse
Affiliation(s)
- Ramona M Vejandla
- The Heart Institute, Department of Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee.,Children's Foundation Research Institute, Le Bonheur Children's Hospital, Memphis, Tennessee
| | - Buyan-Ochir Orgil
- The Heart Institute, Department of Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee.,Children's Foundation Research Institute, Le Bonheur Children's Hospital, Memphis, Tennessee
| | - Neely R Alberson
- The Heart Institute, Department of Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee.,Children's Foundation Research Institute, Le Bonheur Children's Hospital, Memphis, Tennessee
| | - Ning Li
- The Heart Institute, Department of Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee.,Children's Foundation Research Institute, Le Bonheur Children's Hospital, Memphis, Tennessee.,Department of Cardiology, Second Affiliated Hospital, Harbin Medical University, Harbin, China
| | - Undral Munkhsaikhan
- The Heart Institute, Department of Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee.,Children's Foundation Research Institute, Le Bonheur Children's Hospital, Memphis, Tennessee
| | - Zaza Khuchua
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.,Department of Biochemistry, Sechenov University, Moscow, Russia.,Department of Biology and Biotechnology, Higher School of Economics, Moscow, Russia
| | - Ruben Martherus
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Evren U Azeloglu
- Department of Medicine, Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Fuyi Xu
- Department of Genetics, Genomics, and Informatics, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Lu Lu
- Department of Genetics, Genomics, and Informatics, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Jeffrey A Towbin
- The Heart Institute, Department of Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee.,Children's Foundation Research Institute, Le Bonheur Children's Hospital, Memphis, Tennessee.,Pediatric Cardiology, St. Jude Children's Research Hospital, Memphis, Tennessee
| | - Enkhsaikhan Purevjav
- The Heart Institute, Department of Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee.,Children's Foundation Research Institute, Le Bonheur Children's Hospital, Memphis, Tennessee
| |
Collapse
|
11
|
Solís C, Solaro RJ. Novel insights into sarcomere regulatory systems control of cardiac thin filament activation. J Gen Physiol 2021; 153:211903. [PMID: 33740037 PMCID: PMC7988513 DOI: 10.1085/jgp.202012777] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 02/23/2021] [Indexed: 12/11/2022] Open
Abstract
Our review focuses on sarcomere regulatory mechanisms with a discussion of cardiac-specific modifications to the three-state model of thin filament activation from a blocked to closed to open state. We discuss modulation of these thin filament transitions by Ca2+, by crossbridge interactions, and by thick filament–associated proteins, cardiac myosin–binding protein C (cMyBP-C), cardiac regulatory light chain (cRLC), and titin. Emerging evidence supports the idea that the cooperative activation of the thin filaments despite a single Ca2+ triggering regulatory site on troponin C (cTnC) cannot be considered in isolation of other functional domains of the sarcomere. We discuss long- and short-range interactions among these domains with the regulatory units of thin filaments, including proteins at the barbed end at the Z-disc and the pointed end near the M-band. Important to these discussions is the ever-increasing understanding of the role of cMyBP-C, cRLC, and titin filaments. Detailed knowledge of these control processes is critical to the understanding of mechanisms sustaining physiological cardiac state with varying hemodynamic load, to better defining genetic and acquired cardiac disorders, and to developing targets for therapies at the level of the sarcomeres.
Collapse
Affiliation(s)
- Christopher Solís
- University of Illinois at Chicago, College of Medicine, Department of Physiology and Biophysics and Center for Cardiovascular Research, Chicago, IL
| | - R John Solaro
- University of Illinois at Chicago, College of Medicine, Department of Physiology and Biophysics and Center for Cardiovascular Research, Chicago, IL
| |
Collapse
|
12
|
Ge X, Zhang T, Yu X, Muwonge AN, Anandakrishnan N, Wong NJ, Haydak JC, Reid JM, Fu J, Wong JS, Bhattacharya S, Cuttitta CM, Zhong F, Gordon RE, Salem F, Janssen W, Hone JC, Zhang A, Li H, He JC, Gusella GL, Campbell KN, Azeloglu EU. LIM-Nebulette Reinforces Podocyte Structural Integrity by Linking Actin and Vimentin Filaments. J Am Soc Nephrol 2020; 31:2372-2391. [PMID: 32737144 DOI: 10.1681/asn.2019121261] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 06/06/2020] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Maintenance of the intricate interdigitating morphology of podocytes is crucial for glomerular filtration. One of the key aspects of specialized podocyte morphology is the segregation and organization of distinct cytoskeletal filaments into different subcellular components, for which the exact mechanisms remain poorly understood. METHODS Cells from rats, mice, and humans were used to describe the cytoskeletal configuration underlying podocyte structure. Screening the time-dependent proteomic changes in the rat puromycin aminonucleoside-induced nephropathy model correlated the actin-binding protein LIM-nebulette strongly with glomerular function. Single-cell RNA sequencing and immunogold labeling were used to determine Nebl expression specificity in podocytes. Automated high-content imaging, super-resolution microscopy, atomic force microscopy (AFM), live-cell imaging of calcium, and measurement of motility and adhesion dynamics characterized the physiologic role of LIM-nebulette in podocytes. RESULTS Nebl knockout mice have increased susceptibility to adriamycin-induced nephropathy and display morphologic, cytoskeletal, and focal adhesion abnormalities with altered calcium dynamics, motility, and Rho GTPase activity. LIM-nebulette expression is decreased in diabetic nephropathy and FSGS patients at both the transcript and protein level. In mice, rats, and humans, LIM-nebulette expression is localized to primary, secondary, and tertiary processes of podocytes, where it colocalizes with focal adhesions as well as with vimentin fibers. LIM-nebulette shRNA knockdown in immortalized human podocytes leads to dysregulation of vimentin filament organization and reduced cellular elasticity as measured by AFM indentation. CONCLUSIONS LIM-nebulette is a multifunctional cytoskeletal protein that is critical in the maintenance of podocyte structural integrity through active reorganization of focal adhesions, the actin cytoskeleton, and intermediate filaments.
Collapse
Affiliation(s)
- Xuhua Ge
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Tao Zhang
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Xiaoxia Yu
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Alecia N Muwonge
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Nanditha Anandakrishnan
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Nicholas J Wong
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Jonathan C Haydak
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Jordan M Reid
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Jia Fu
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Jenny S Wong
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Smiti Bhattacharya
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York.,Department of Mechanical Engineering, Columbia University, New York, New York
| | - Christina M Cuttitta
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Fang Zhong
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Ronald E Gordon
- Department of Pathology, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Fadi Salem
- Department of Pathology, Icahn School of Medicine at Mount Sinai, New York, New York
| | - William Janssen
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York
| | - James C Hone
- Department of Mechanical Engineering, Columbia University, New York, New York
| | - Aihua Zhang
- Department of Nephrology, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Hong Li
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers University-New Jersey Medical School, Newark, New Jersey
| | - John C He
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York.,Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York
| | - G Luca Gusella
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Kirk N Campbell
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Evren U Azeloglu
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York .,Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York
| |
Collapse
|
13
|
Filomena MC, Yamamoto DL, Caremani M, Kadarla VK, Mastrototaro G, Serio S, Vydyanath A, Mutarelli M, Garofalo A, Pertici I, Knöll R, Nigro V, Luther PK, Lieber RL, Beck MR, Linari M, Bang M. Myopalladin promotes muscle growth through modulation of the serum response factor pathway. J Cachexia Sarcopenia Muscle 2020; 11:169-194. [PMID: 31647200 PMCID: PMC7015241 DOI: 10.1002/jcsm.12486] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 07/01/2019] [Accepted: 07/22/2019] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Myopalladin (MYPN) is a striated muscle-specific, immunoglobulin-containing protein located in the Z-line and I-band of the sarcomere as well as the nucleus. Heterozygous MYPN gene mutations are associated with hypertrophic, dilated, and restrictive cardiomyopathy, and homozygous loss-of-function truncating mutations have recently been identified in patients with cap myopathy, nemaline myopathy, and congenital myopathy with hanging big toe. METHODS Constitutive MYPN knockout (MKO) mice were generated, and the role of MYPN in skeletal muscle was studied through molecular, cellular, biochemical, structural, biomechanical, and physiological studies in vivo and in vitro. RESULTS MKO mice were 13% smaller compared with wild-type controls and exhibited a 48% reduction in myofibre cross-sectional area (CSA) and significantly increased fibre number. Similarly, reduced myotube width was observed in MKO primary myoblast cultures. Biomechanical studies showed reduced isometric force and power output in MKO mice as a result of the reduced CSA, whereas the force developed by each myosin molecular motor was unaffected. While the performance by treadmill running was similar in MKO and wild-type mice, MKO mice showed progressively decreased exercise capability, Z-line damage, and signs of muscle regeneration following consecutive days of downhill running. Additionally, MKO muscle exhibited progressive Z-line widening starting from 8 months of age. RNA-sequencing analysis revealed down-regulation of serum response factor (SRF)-target genes in muscles from postnatal MKO mice, important for muscle growth and differentiation. The SRF pathway is regulated by actin dynamics as binding of globular actin to the SRF-cofactor myocardin-related transcription factor A (MRTF-A) prevents its translocation to the nucleus where it binds and activates SRF. MYPN was found to bind and bundle filamentous actin as well as interact with MRTF-A. In particular, while MYPN reduced actin polymerization, it strongly inhibited actin depolymerization and consequently increased MRTF-A-mediated activation of SRF signalling in myogenic cells. Reduced myotube width in MKO primary myoblast cultures was rescued by transduction with constitutive active SRF, demonstrating that MYPN promotes skeletal muscle growth through activation of the SRF pathway. CONCLUSIONS Myopalladin plays a critical role in the control of skeletal muscle growth through its effect on actin dynamics and consequently the SRF pathway. In addition, MYPN is important for the maintenance of Z-line integrity during exercise and aging. These results suggest that muscle weakness in patients with biallelic MYPN mutations may be associated with reduced myofibre CSA and SRF signalling and that the disease phenotype may be aggravated by exercise.
Collapse
Affiliation(s)
- Maria Carmela Filomena
- Institute of Genetic and Biomedical Research (IRGB), Milan UnitNational Research CouncilMilanItaly
- Humanitas Clinical and Research CenterRozzanoMilanItaly
| | - Daniel L. Yamamoto
- Institute of Genetic and Biomedical Research (IRGB), Milan UnitNational Research CouncilMilanItaly
| | - Marco Caremani
- Department of BiologyUniversity of FlorenceSesto FiorentinoFlorenceItaly
| | | | | | - Simone Serio
- Humanitas Clinical and Research CenterRozzanoMilanItaly
| | | | | | - Arcamaria Garofalo
- Telethon Institute of Genetics and Medicine (TIGEM)PozzuoliItaly
- Department of Precision MedicineUniversity of Campania “Luigi Vanvitelli”NaplesItaly
| | - Irene Pertici
- Department of BiologyUniversity of FlorenceSesto FiorentinoFlorenceItaly
| | - Ralph Knöll
- Integrated Cardio Metabolic Centre (ICMC), Myocardial GeneticsKarolinska Institutet, University Hospital, Heart and Vascular ThemeSweden
- Research and Early Development, Cardiovascular, Renal and Metabolic Diseases (CVRM), Biopharmaceuticals R&DAstraZenecaMölndalSweden
| | - Vincenzo Nigro
- Telethon Institute of Genetics and Medicine (TIGEM)PozzuoliItaly
- Department of Precision MedicineUniversity of Campania “Luigi Vanvitelli”NaplesItaly
| | | | - Richard L. Lieber
- Shirley Ryan AbilityLab and Hines V.A. Medical Center ChicagoChicagoILUSA
- Department of Physical Medicine and RehabilitationNorthwestern UniversityChicagoILUSA
- Department of Orthopaedic SurgeryUniversity of California San DiegoLa JollaCAUSA
| | - Moriah R. Beck
- Department of ChemistryWichita State UniversityWichitaKSUSA
| | - Marco Linari
- Department of BiologyUniversity of FlorenceSesto FiorentinoFlorenceItaly
| | - Marie‐Louise Bang
- Institute of Genetic and Biomedical Research (IRGB), Milan UnitNational Research CouncilMilanItaly
- Humanitas Clinical and Research CenterRozzanoMilanItaly
| |
Collapse
|
14
|
Deficiency of nuclear receptor interaction protein leads to cardiomyopathy by disrupting sarcomere structure and mitochondrial respiration. J Mol Cell Cardiol 2019; 137:9-24. [PMID: 31629737 DOI: 10.1016/j.yjmcc.2019.09.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 09/15/2019] [Accepted: 09/17/2019] [Indexed: 01/28/2023]
Abstract
BACKGROUND Cardiomyopathy is a common and lethal complication in patients with limb-girdle muscular dystrophy (LGMD), one of the most prevalent forms of muscular dystrophy. The pathogenesis underlying LGMD-related cardiomyopathy remains unclear. NRIP (gene name DCAF6), a Ca2+-dependent calmodulin binding protein, was reduced in dystrophic muscles from LGMD patients. Mice lacking NRIP exhibit a myopathic phenotype resembling that in LGMD patients, making NRIP deficiency a potential culprit leading to cardiomyopathy. This study aimed to determine if NRIP deficiency leads to cardiomyopathy and to explore the underlying molecular mechanisms. METHODS AND RESULTS NRIP expression was reduced in both human and mouse failing hearts. Muscle-specific NRIP knockout (MCK-Cre::Dcaf6flox/flox) mouse heart and isolated cardiomyocytes exhibited markedly reduced contractility. Transmission electron microscopy revealed abnormal sarcomere structures and mitochondrial morphology in MCK-Cre::Dcaf6flox/flox hearts. Protein co-immunoprecipitation and confocal imaging revealed that NRIP interacts with α-actinin 2 (ACTN2) at the Z-disc. We found that NRIP facilitated ACTN2-mediated F-actin bundling, and that NRIP deficiency resulted in reduced binding between Z-disc proteins ACTN2 and Cap-Z. In addition, NRIP-deficiency led to increased mitochondrial ROS and impaired mitochondrial respiration/ATP production owing to elevated cellular NADH/NAD+ ratios. Treatment with mitochondria-directed antioxidant mitoTEMPO or NAD+ precursor nicotinic acid restored mitochondrial function and cardiac contractility in MCK-Cre::Dcaf6flox/flox mice. CONCLUSIONS NRIP is essential to maintain sarcomere structure and mitochondrial/contractile function in cardiomyocytes. Our results revealed a novel role for NRIP deficiency in the pathogenesis of LGMD and heart failure. Targeting NRIP, therefore, could be a powerful new approach to treat myocardial dysfunction in LGMD and heart failure patients.
Collapse
|
15
|
Gregorich ZR, Patel JR, Cai W, Lin Z, Heurer R, Fitzsimons DP, Moss RL, Ge Y. Deletion of Enigma Homologue from the Z-disc slows tension development kinetics in mouse myocardium. J Gen Physiol 2019; 151:670-679. [PMID: 30642915 PMCID: PMC6504290 DOI: 10.1085/jgp.201812214] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 12/20/2018] [Indexed: 12/14/2022] Open
Abstract
Enigma Homologue (ENH) is a component of the Z-disc, a structure that anchors actin filaments in the contractile unit of muscle, the sarcomere. Cardiac-specific ablation of ENH protein expression causes contractile dysfunction that ultimately culminates in dilated cardiomyopathy. However, whether ENH is involved in the regulation of myocardial contractility is unknown. To determine if ENH is required for the mechanical activity of cardiac muscle, we analyze muscle mechanics of isolated trabeculae from the hearts of ENH +/+ and ENH -/- mice. We detected no differences in steady-state mechanical properties but show that when muscle fibers are allowed to relax and then are restretched, the rate at which tension redevelops is depressed in ENH -/- mouse myocardium relative to that in ENH +/+ myocardium. SDS-PAGE analysis demonstrated that the expression of β-myosin heavy chain is increased in ENH -/- mouse myocardium, which could partially, but not completely, account for the depression in tension redevelopment kinetics. Using top-down proteomics analysis, we found that the expression of other thin/thick filament regulatory proteins is unaltered, although the phosphorylation of a cardiac troponin T isoform, cardiac troponin I, and myosin regulatory light chain is decreased in ENH -/- mouse myocardium. Nevertheless, these alterations are very small and thus insufficient to explain slowed tension redevelopment kinetics in ENH -/- mouse myocardium. These data suggest that the ENH protein influences tension redevelopment kinetics in mouse myocardium, possibly by affecting cross-bridge cycling kinetics. Previous studies also indicate that ablation of specific Z-disc proteins in myocardium slows contraction kinetics, which could also be a contributing factor in this study.
Collapse
Affiliation(s)
- Zachery R Gregorich
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI.,Molecular and Cellular Pharmacology Training Program, University of Wisconsin-Madison, Madison, WI
| | - Jitandrakumar R Patel
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI.,University of Wisconsin-Madison Cardiovascular Research Center, University of Wisconsin-Madison, Madison, WI
| | - Wenxuan Cai
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI.,Molecular and Cellular Pharmacology Training Program, University of Wisconsin-Madison, Madison, WI
| | - Ziqing Lin
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI.,Human Proteomics Program, University of Wisconsin-Madison, Madison, WI
| | - Rachel Heurer
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI
| | - Daniel P Fitzsimons
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI
| | - Richard L Moss
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI .,University of Wisconsin-Madison Cardiovascular Research Center, University of Wisconsin-Madison, Madison, WI.,Human Proteomics Program, University of Wisconsin-Madison, Madison, WI
| | - Ying Ge
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI .,Molecular and Cellular Pharmacology Training Program, University of Wisconsin-Madison, Madison, WI.,University of Wisconsin-Madison Cardiovascular Research Center, University of Wisconsin-Madison, Madison, WI.,Human Proteomics Program, University of Wisconsin-Madison, Madison, WI
| |
Collapse
|
16
|
Qiu X, Feng JR, Wang F, Chen PF, Chen XX, Zhou R, Chang Y, Liu J, Zhao Q. Profiles of differentially expressed genes and overexpression of NEBL indicates a positive prognosis in patients with colorectal cancer. Mol Med Rep 2017; 17:3028-3034. [PMID: 29257257 PMCID: PMC5783523 DOI: 10.3892/mmr.2017.8210] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 10/27/2017] [Indexed: 12/29/2022] Open
Abstract
The present study aimed to identify differentially expressed genes (DEGs) in colorectal cancer (CRC) and provide novel prognostic biomarkers for CRC. The microarray dataset GSE41258 was used to screen DEGs of CRC. Subsequently, a protein-protein interaction network of DEGs and Gene Ontology analysis were performed to identify hub genes and associated biological processes. Nebulette (NEBL) and complement C1q like 1 (C1QL1) were validated using reverse transcription-quantitative polymerase chain reaction in patients with CRC. Survival analysis was performed for the two hub genes. GSE41258 dataset included 182 CRC samples and 54 normal tissues. A total of 759 DEGs, including 279 upregulated and 480 downregulated were screened between both groups. NEBL and C1QL1 were identified as the two hub genes and upregulated genes involved in various biological processes, including ‘regulation of biological quality’ and ‘response to stimulus’, respectively. Additionally, the overexpression of NEBL and C1QL1 in experimental validation was consistent with the aforementioned bioinformatics analysis results. Survival analysis suggested that overexpressed NEBL in patients with CRC was associated with a positive prognosis for overall survival. In conclusion, CRC was associated with a large group of DEGs. From the upregulated genes, overexpressed NEBL in patients CRC indicated a positive prognosis for overall survival and may be used as a prognostic biomarker for patients with CRC.
Collapse
Affiliation(s)
- Xiao Qiu
- Department of Gastroenterology, Zhongnan Hospital of Wuhan University, The Hubei Clinical Center and Key Laboratory of Intestinal and Colorectal Diseases, Wuhan, Hubei 430071, P.R. China
| | - Jue-Rong Feng
- Department of Gastroenterology, Zhongnan Hospital of Wuhan University, The Hubei Clinical Center and Key Laboratory of Intestinal and Colorectal Diseases, Wuhan, Hubei 430071, P.R. China
| | - Fan Wang
- Department of Gastroenterology, Zhongnan Hospital of Wuhan University, The Hubei Clinical Center and Key Laboratory of Intestinal and Colorectal Diseases, Wuhan, Hubei 430071, P.R. China
| | - Peng-Fei Chen
- Department of Gastroenterology, Zhongnan Hospital of Wuhan University, The Hubei Clinical Center and Key Laboratory of Intestinal and Colorectal Diseases, Wuhan, Hubei 430071, P.R. China
| | - Xiao-Xing Chen
- Department of Gastroenterology, Zhongnan Hospital of Wuhan University, The Hubei Clinical Center and Key Laboratory of Intestinal and Colorectal Diseases, Wuhan, Hubei 430071, P.R. China
| | - Rui Zhou
- Department of Gastroenterology, Zhongnan Hospital of Wuhan University, The Hubei Clinical Center and Key Laboratory of Intestinal and Colorectal Diseases, Wuhan, Hubei 430071, P.R. China
| | - Ying Chang
- Department of Gastroenterology, Zhongnan Hospital of Wuhan University, The Hubei Clinical Center and Key Laboratory of Intestinal and Colorectal Diseases, Wuhan, Hubei 430071, P.R. China
| | - Jing Liu
- Department of Gastroenterology, Zhongnan Hospital of Wuhan University, The Hubei Clinical Center and Key Laboratory of Intestinal and Colorectal Diseases, Wuhan, Hubei 430071, P.R. China
| | - Qiu Zhao
- Department of Gastroenterology, Zhongnan Hospital of Wuhan University, The Hubei Clinical Center and Key Laboratory of Intestinal and Colorectal Diseases, Wuhan, Hubei 430071, P.R. China
| |
Collapse
|
17
|
Abstract
Cardiac and skeletal striated muscles are intricately designed machines responsible for muscle contraction. Coordination of the basic contractile unit, the sarcomere, and the complex cytoskeletal networks are critical for contractile activity. The sarcomere is comprised of precisely organized individual filament systems that include thin (actin), thick (myosin), titin, and nebulin. Connecting the sarcomere to other organelles (e.g., mitochondria and nucleus) and serving as the scaffold to maintain cellular integrity are the intermediate filaments. The costamere, on the other hand, tethers the sarcomere to the cell membrane. Unique structures like the intercalated disc in cardiac muscle and the myotendinous junction in skeletal muscle help synchronize and transmit force. Intense investigation has been done on many of the proteins that make up these cytoskeletal assemblies. Yet the details of their function and how they interconnect have just started to be elucidated. A vast number of human myopathies are contributed to mutations in muscle proteins; thus understanding their basic function provides a mechanistic understanding of muscle disorders. In this review, we highlight the components of striated muscle with respect to their interactions, signaling pathways, functions, and connections to disease. © 2017 American Physiological Society. Compr Physiol 7:891-944, 2017.
Collapse
Affiliation(s)
- Christine A Henderson
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, Arizona, USA.,Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, Arizona, USA
| | - Christopher G Gomez
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, Arizona, USA.,Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, Arizona, USA
| | - Stefanie M Novak
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, Arizona, USA.,Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, Arizona, USA
| | - Lei Mi-Mi
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, Arizona, USA.,Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, Arizona, USA
| | - Carol C Gregorio
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, Arizona, USA.,Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, Arizona, USA
| |
Collapse
|
18
|
Abstract
Striated cardiac and skeletal muscles play very different roles in the body, but they are similar at the molecular level. In particular, contraction, regardless of the type of muscle, is a precise and complex process involving the integral protein myofilaments and their associated regulatory components. The smallest functional unit of muscle contraction is the sarcomere. Within the sarcomere can be found a sophisticated ensemble of proteins associated with the thick filaments (myosin, myosin binding protein-C, titin, and obscurin) and thin myofilaments (actin, troponin, tropomyosin, nebulin, and nebulette). These parallel thick and thin filaments slide across one another, pulling the two ends of the sarcomere together to regulate contraction. More specifically, the regulation of both timing and force of contraction is accomplished through an intricate network of intra- and interfilament interactions belonging to each myofilament. This review introduces the sarcomere proteins involved in striated muscle contraction and places greater emphasis on the more recently identified and less well-characterized myofilaments: cardiac myosin binding protein-C, titin, nebulin, and obscurin. © 2017 American Physiological Society. Compr Physiol 7:675-692, 2017.
Collapse
Affiliation(s)
- Brian Leei Lin
- Department of Cell and Molecular Physiology, Health Sciences Division, Loyola University Chicago, Maywood, Illinois, USA
| | - Taejeong Song
- Department of Cell and Molecular Physiology, Health Sciences Division, Loyola University Chicago, Maywood, Illinois, USA.,Department of Internal Medicine, Heart, Lung and Vascular Institute, Division of Cardiovascular Health and Sciences, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - Sakthivel Sadayappan
- Department of Cell and Molecular Physiology, Health Sciences Division, Loyola University Chicago, Maywood, Illinois, USA.,Department of Internal Medicine, Heart, Lung and Vascular Institute, Division of Cardiovascular Health and Sciences, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| |
Collapse
|
19
|
Abstract
In this review we discuss the history and the current state of ideas related to the mechanism of size regulation of the thick (myosin) and thin (actin) filaments in vertebrate striated muscles. Various hypotheses have been considered during of more than half century of research, recently mostly involving titin and nebulin acting as templates or 'molecular rulers', terminating exact assembly. These two giant, single-polypeptide, filamentous proteins are bound in situ along the thick and thin filaments, respectively, with an almost perfect match in the respective lengths and structural periodicities. However, evidence still questions the possibility that the proteins function as templates, or scaffolds, on which the thin and thick filaments could be assembled. In addition, the progress in muscle research during the last decades highlighted a number of other factors that could potentially be involved in the mechanism of length regulation: molecular chaperones that may guide folding and assembly of actin and myosin; capping proteins that can influence the rates of assembly-disassembly of the myofilaments; Ca2+ transients that can activate or deactivate protein interactions, etc. The entire mechanism of sarcomere assembly appears complex and highly dynamic. This mechanism is also capable of producing filaments of about the correct size without titin and nebulin. What then is the role of these proteins? Evidence points to titin and nebulin stabilizing structures of the respective filaments. This stabilizing effect, based on linear proteins of a fixed size, implies that titin and nebulin are indeed molecular rulers of the filaments. Although the proteins may not function as templates in the assembly of the filaments, they measure and stabilize exactly the same size of the functionally important for the muscles segments in each of the respective filaments.
Collapse
|
20
|
Hernandez DA, Bennett CM, Dunina-Barkovskaya L, Wedig T, Capetanaki Y, Herrmann H, Conover GM. Nebulette is a powerful cytolinker organizing desmin and actin in mouse hearts. Mol Biol Cell 2016; 27:3869-3882. [PMID: 27733623 PMCID: PMC5170609 DOI: 10.1091/mbc.e16-04-0237] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 08/31/2016] [Accepted: 10/05/2016] [Indexed: 12/11/2022] Open
Abstract
Nebulette physically links desmin to sarcomeric actin in hearts. An intact desmin network is required for nebulette to function as major actin-binding protein in sarcomeres. This study provides biochemical evidence that the desmin–nebulette complex is involved in filament-forming desminopathy. In the hearts of patients bearing nebulette mutations, a severe general disorganization in cardiomyocytes of the extrasarcomeric desmin intermediate filament system is frequently observed. However, the molecular and functional relationship between the desmin cytoskeleton and nebulette-containing sarcomeres is still unclear. Here we report a high-affinity in vitro interaction between nebulette and desmin filaments. A major interaction site has been mapped to the desmin α-helical rod domain, indicating that the filament core is directly involved in the binding of nebulette. The disease-mutant desmin variants E245D and T453I exhibited increased binding affinity for nebulette, delayed filament assembly kinetics, and caused significant weakening of networks. In isolated chick cardiomyocytes and sections from canine heart, we revealed by ground-state depletion and confocal microscopies that module 5 of nebulette extends outward from Z-disk–associated desmin filaments toward the center of the sarcomere. Accordingly, in the myocardium of Des−/− mice, elevated levels of cardiac actin correlated with alterations in the distribution of nebulette. Our data suggest that a well-organized desmin network is required to accommodate an optimal conformation of nebulette on sarcomeres to bind and recruit cardiac α-actin. Hence we propose that nebulette acts in synergy with nebulin to reinforce and temporally fine-tune striated muscle relaxation–contraction cycles.
Collapse
Affiliation(s)
- Daniel A Hernandez
- Department of Biochemistry & Biophysics, Texas A&M University, College Station, TX 77843-3474
| | - Christina M Bennett
- Department of Biochemistry & Biophysics, Texas A&M University, College Station, TX 77843-3474
| | | | - Tatjana Wedig
- Division of Molecular Genetics, German Cancer Research Center (DKFZ), D-69120 Heidelberg, Germany
| | - Yassemi Capetanaki
- Center of Basic Research, Biomedical Research Foundation Academy of Athens, Athens 11527, Greece
| | - Harald Herrmann
- Division of Molecular Genetics, German Cancer Research Center (DKFZ), D-69120 Heidelberg, Germany.,Institute of Neuropathology, University Hospital Erlangen, D-91054 Erlangen, Germany
| | - Gloria M Conover
- Department of Biochemistry & Biophysics, Texas A&M University, College Station, TX 77843-3474
| |
Collapse
|
21
|
Bang ML. Animal Models of Congenital Cardiomyopathies Associated With Mutations in Z-Line Proteins. J Cell Physiol 2016; 232:38-52. [PMID: 27171814 DOI: 10.1002/jcp.25424] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 05/10/2016] [Indexed: 01/15/2023]
Abstract
The cardiac Z-line at the boundary between sarcomeres is a multiprotein complex connecting the contractile apparatus with the cytoskeleton and the extracellular matrix. The Z-line is important for efficient force generation and transmission as well as the maintenance of structural stability and integrity. Furthermore, it is a nodal point for intracellular signaling, in particular mechanosensing and mechanotransduction. Mutations in various genes encoding Z-line proteins have been associated with different cardiomyopathies, including dilated cardiomyopathy, hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, restrictive cardiomyopathy, and left ventricular noncompaction, and mutations even within the same gene can cause widely different pathologies. Animal models have contributed to a great advancement in the understanding of the physiological function of Z-line proteins and the pathways leading from mutations in Z-line proteins to cardiomyopathy, although genotype-phenotype prediction remains a great challenge. This review presents an overview of the currently available animal models for Z-line and Z-line associated proteins involved in human cardiomyopathies with special emphasis on knock-in and transgenic mouse models recapitulating the clinical phenotypes of human cardiomyopathy patients carrying mutations in Z-line proteins. Pros and cons of mouse models will be discussed and a future outlook will be given. J. Cell. Physiol. 232: 38-52, 2017. © 2016 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Marie-Louise Bang
- Institute of Genetic and Biomedical Research, UOS Milan, National Research Council and Humanitas Clinical and Research Center, Rozzano, Milan, Italy.
| |
Collapse
|
22
|
Kuo HC, Li SC, Guo MMH, Huang YH, Yu HR, Huang FC, Jiao F, Kuo HC, Andrade J, Chan WC. Genome-Wide Association Study Identifies Novel Susceptibility Genes Associated with Coronary Artery Aneurysm Formation in Kawasaki Disease. PLoS One 2016; 11:e0154943. [PMID: 27171184 PMCID: PMC4865092 DOI: 10.1371/journal.pone.0154943] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 04/21/2016] [Indexed: 11/18/2022] Open
Abstract
Kawasaki disease (KD) or Kawasaki syndrome is known as a vasculitis of small to medium-sized vessels, and coronary arteries are predominantly involved in childhood. Generally, 20–25% of untreated with IVIG and 3–5% of treated KD patients have been developed coronary artery lesions (CALs), such as dilatation and aneurysm. Understanding how coronary artery aneurysms (CAAs) are established and maintained in KD patients is therefore of great importance. Upon our previous genotyping data of 157 valid KD subjects, a genome-wide association study (GWAS) has been conducted among 11 (7%) CAA-developed KD patients to reveal five significant genetic variants passed pre-defined thresholds and resulted in two novel susceptibility protein-coding genes, which are NEBL (rs16921209 (P = 7.44 × 10−9; OR = 32.22) and rs7922552 (P = 8.43 × 10−9; OR = 32.0)) and TUBA3C (rs17076896 (P = 8.04 × 10−9; OR = 21.03)). Their known functions have been reported to associate with cardiac muscle and tubulin, respectively. As a result, this might imply their putative roles of establishing CAAs during KD progression. Additionally, various model analyses have been utilized to determine dominant and recessive inheritance patterns of identified susceptibility mutations. Finally, all susceptibility genes hit by significant genetic variants were further investigated and the top three representative gene-ontology (GO) clusters were regulation of cell projection organization, neuron recognition, and peptidyl-threonine phosphorylation. Our results help to depict the potential routes of the pathogenesis of CAAs in KD patients and will facilitate researchers to improve the diagnosis and prognosis of KD in personalized medicine.
Collapse
Affiliation(s)
- Ho-Chang Kuo
- Department of Pediatrics and Kawasaki Disease Center, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Sung-Chou Li
- Genomics and Proteomics Core Laboratory, Department of Medical Research, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Mindy Ming-Huey Guo
- Department of Pediatrics and Kawasaki Disease Center, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Ying-Hsien Huang
- Department of Pediatrics and Kawasaki Disease Center, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Hong-Ren Yu
- Department of Pediatrics and Kawasaki Disease Center, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Fu-Chen Huang
- Department of Pediatrics and Kawasaki Disease Center, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Fuyong Jiao
- Children's Hospital of Shaanxi Provincial People's Hospital and Jiaotong University, Xi'an, China
| | - Hsing-Chun Kuo
- Department of Nursing, Chang Gung University of Science and Technology, Chiayi, Taiwan
| | - Jorge Andrade
- Center for Research Informatics, The University of Chicago, Chicago, Illinois, 60637, United States of America
| | - Wen-Ching Chan
- Genomics and Proteomics Core Laboratory, Department of Medical Research, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan
- Center for Research Informatics, The University of Chicago, Chicago, Illinois, 60637, United States of America
- * E-mail:
| |
Collapse
|
23
|
Abstract
The members of the nebulin protein family, including nebulin, nebulette, LASP-1, LASP-2, and N-RAP, contain various numbers of nebulin repeats and bind to actin, but are otherwise heterogeneous with regard to size, expression pattern, and function. This review focuses on the roles of nebulin family members in the heart. Nebulin is the largest member predominantly expressed in skeletal muscle, where it stretches along the thin filament. In heart, nebulin is detectable only at low levels and its absence has no apparent effects. Nebulette is similar in structure to the nebulin C-terminal Z-line region and specifically expressed in heart. Nebulette gene mutations have been identified in dilated cardiomyopathy patients and transgenic mice overexpressing nebulette mutants partially recapitulate the human pathology. In contrast, nebulette knockout mice show no functional phenotype, but exhibit Z-line widening. LASP-2 is an isoform of nebulette expressed in multiple tissues, including the heart. It is present in the Z-line and intercalated disc and able to bind and cross-link filamentous actin. LASP-1 is similar in structure to LASP-2, but expressed only in non-muscle tissue. N-RAP is present in myofibril precursors during myofibrillogenesis and thought to be involved in myofibril assembly, while it is localized at the intercalated disc in adult heart. Additional in vivo models are required to provide further insights into the functions of nebulin family members in the heart.
Collapse
Affiliation(s)
- Marie-Louise Bang
- Institute of Genetic and Biomedical Research, UOS Milan, National Research Council
| | | |
Collapse
|