1
|
Iorga B, Schwanke K, Weber N, Wendland M, Greten S, Piep B, Dos Remedios CG, Martin U, Zweigerdt R, Kraft T, Brenner B. Differences in Contractile Function of Myofibrils within Human Embryonic Stem Cell-Derived Cardiomyocytes vs. Adult Ventricular Myofibrils Are Related to Distinct Sarcomeric Protein Isoforms. Front Physiol 2018; 8:1111. [PMID: 29403388 PMCID: PMC5780405 DOI: 10.3389/fphys.2017.01111] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Accepted: 12/15/2017] [Indexed: 01/10/2023] Open
Abstract
Characterizing the contractile function of human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) is key for advancing their utility for cellular disease models, promoting cell based heart repair, or developing novel pharmacological interventions targeting cardiac diseases. The aim of the present study was to understand whether steady-state and kinetic force parameters of β-myosin heavy chain (βMyHC) isoform-expressing myofibrils within human embryonic stem cell-derived cardiomyocytes (hESC-CMs) differentiated in vitro resemble those of human ventricular myofibrils (hvMFs) isolated from adult donor hearts. Contractile parameters were determined using the same micromechanical method and experimental conditions for both types of myofibrils. We identified isoforms and phosphorylation of main sarcomeric proteins involved in the modulation of force generation of both, chemically demembranated hESC-CMs (d-hESC-CMs) and hvMFs. Our results indicate that at saturating Ca2+ concentration, both human-derived contractile systems developed forces with similar rate constants (0.66 and 0.68 s−1), reaching maximum isometric force that was significantly smaller for d-hESC-CMs (42 kPa) than for hvMFs (94 kPa). At submaximal Ca2+-activation, where intact cardiomyocytes normally operate, contractile parameters of d-hESC-CMs and hvMFs exhibited differences. Ca2+ sensitivity of force was higher for d-hESC-CMs (pCa50 = 6.04) than for hvMFs (pCa50 = 5.80). At half-maximum activation, the rate constant for force redevelopment was significantly faster for d-hESC-CMs (0.51 s−1) than for hvMFs (0.28 s−1). During myofibril relaxation, kinetics of the slow force decay phase were significantly faster for d-hESC-CMs (0.26 s−1) than for hvMFs (0.21 s−1), while kinetics of the fast force decay were similar and ~20x faster. Protein analysis revealed that hESC-CMs had essentially no cardiac troponin-I, and partially non-ventricular isoforms of some other sarcomeric proteins, explaining the functional discrepancies. The sarcomeric protein isoform pattern of hESC-CMs had features of human cardiomyocytes at an early developmental stage. The study indicates that morphological and ultrastructural maturation of βMyHC isoform-expressing hESC-CMs is not necessarily accompanied by ventricular-like expression of all sarcomeric proteins. Our data suggest that hPSC-CMs could provide useful tools for investigating inherited cardiac diseases affecting contractile function during early developmental stages.
Collapse
Affiliation(s)
- Bogdan Iorga
- Department of Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany.,Department of Physical Chemistry, Faculty of Chemistry, University of Bucharest, Bucharest, Romania
| | - Kristin Schwanke
- Department of Cardiac, Thoracic, Transplantation and Vascular Surgery, Leibniz Research Laboratories for Biotechnology and Artificial Organs, REBIRTH-Center for Regenerative Medicine, Hannover Medical School, Hannover, Germany
| | - Natalie Weber
- Department of Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
| | - Meike Wendland
- Department of Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
| | - Stephan Greten
- Department of Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
| | - Birgit Piep
- Department of Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
| | | | - Ulrich Martin
- Department of Cardiac, Thoracic, Transplantation and Vascular Surgery, Leibniz Research Laboratories for Biotechnology and Artificial Organs, REBIRTH-Center for Regenerative Medicine, Hannover Medical School, Hannover, Germany
| | - Robert Zweigerdt
- Department of Cardiac, Thoracic, Transplantation and Vascular Surgery, Leibniz Research Laboratories for Biotechnology and Artificial Organs, REBIRTH-Center for Regenerative Medicine, Hannover Medical School, Hannover, Germany
| | - Theresia Kraft
- Department of Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
| | - Bernhard Brenner
- Department of Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
| |
Collapse
|
2
|
Mrkaic A, Rosenn B, Stojanovic I, Tivari S. Troponins, heat shock proteins and glycogen phosphorylase BB in umbilical cord blood of complicated pregnancies. J Matern Fetal Neonatal Med 2017; 30:2978-2984. [PMID: 27937003 DOI: 10.1080/14767058.2016.1270935] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
PURPOSE OF THE STUDY Heat shock proteins (Hsp) are evolutionary conserved molecules with a chaperone role in cell survival. We hypothesized that cord blood concentrations of molecules reflecting fetal cardiac muscle insult, including Hsp, troponins cTnI and cTnT, and glycol-phosphorylase BB (GP-BB) would be elevated in pregnancies complicated by gestational diabetes (GDM) or preeclampsia (PIH) compared to healthy controls. MATERIALS AND METHODS Pregnant women admitted for delivery at >28 weeks were divided into four groups: healthy patients delivered vaginally (VAG), healthy patients delivered by c-section (CS), patients with PIH, and patients with GDM. Demographics, clinical characteristics, and cord blood concentrations of Hsp, troponins cTnI and cTnT, and GP-BB were compared between groups. Statistical analyses included t-test, Chi square, and Wilcoxon rank sum as appropriate. RESULTS cTnI concentrations were significantly higher in the PIH group compared to the GDM and VAG groups and they were higher in the CS group compared to the VAG group. Concentrations of Hsp70 were higher in the GDM group compared to the VAG and CS groups. Concentration of GP-BB was higher in the PIH group compared to the VAG group. CONCLUSIONS GP-BB and cTNI are the most sensitive markers for PIH-related fetal myocyte injury as is Hsp70 in pregnancies complicated by GDM.
Collapse
Affiliation(s)
- Ana Mrkaic
- a Mountainview Hospital , Las Vegas , NV , USA
| | - Barak Rosenn
- b Mount Sinai West Hospital , New York , NY , USA
| | | | - Samir Tivari
- d Department of Medicine , Rutgers University , Newark , NJ , USA
| |
Collapse
|
3
|
Effects of Long-Term High-Altitude Hypoxia on Myocardial Protein Kinase A Activity and Troponin I Isoforms in Fetal and Nonpregnant Sheep. ACTA ACUST UNITED AC 2016. [DOI: 10.1016/s1071-55760300042-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
4
|
Broughton KM, Li J, Sarmah E, Warren CM, Lin YH, Henze MP, Sanchez-Freire V, Solaro RJ, Russell B. A myosin activator improves actin assembly and sarcomere function of human-induced pluripotent stem cell-derived cardiomyocytes with a troponin T point mutation. Am J Physiol Heart Circ Physiol 2016; 311:H107-17. [PMID: 27199119 DOI: 10.1152/ajpheart.00162.2016] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 05/02/2016] [Indexed: 11/22/2022]
Abstract
We have investigated cardiac myocytes derived from human-induced pluripotent stem cells (iPSC-CMs) from two normal control and two family members expressing a mutant cardiac troponin T (cTnT-R173W) linked to dilated cardiomyopathy (DCM). cTnT is a regulatory protein of the sarcomeric thin filament. The loss of this basic charge, which is strategically located to control tension, has consequences leading to progressive DCM. iPSC-CMs serve as a valuable platform for understanding clinically relevant mutations in sarcomeric proteins; however, there are important questions to be addressed with regard to myocyte adaptation that we model here by plating iPSC-CMs on softer substrates (100 kPa) to create a more physiologic environment during recovery and maturation of iPSC-CMs after thawing from cryopreservation. During the first week of culture of the iPSC-CMs, we have determined structural and functional characteristics as well as actin assembly dynamics. Shortening, actin content, and actin assembly dynamics were depressed in CMs from the severely affected mutant at 1 wk of culture, but by 2 wk differences were less apparent. Sarcomeric troponin and myosin isoform composition were fetal/neonatal. Furthermore, the troponin complex, reconstituted with wild-type cTnT or recombinant cTnT-R173W, depressed the entry of cross-bridges into the force-generating state, which can be reversed by the myosin activator omecamtiv mecarbil. Therapeutic doses of this drug increased both contractility and the content of F-actin in the mutant iPSC-CMs. Collectively, our data suggest the use of a myosin activation reagent to restore function within patient-specific iPSC-CMs may aid in understanding and treating this familial DCM.
Collapse
Affiliation(s)
- K M Broughton
- Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois
| | - J Li
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois; and
| | - E Sarmah
- Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois
| | - C M Warren
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois; and
| | - Y-H Lin
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois; and
| | - M P Henze
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois; and
| | - V Sanchez-Freire
- Department of Medicine, Division of Cardiology, Stanford University School of Medicine, Stanford, California
| | - R J Solaro
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois; and
| | - B Russell
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois; and
| |
Collapse
|
5
|
Ford SJ, Chandra M. The effects of slow skeletal troponin I expression in the murine myocardium are influenced by development-related shifts in myosin heavy chain isoform. J Physiol 2012; 590:6047-63. [PMID: 22966157 DOI: 10.1113/jphysiol.2012.240085] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Troponin I (TnI) and myosin heavy chain (MHC) are two contractile regulatory proteins that undergo major shifts in isoform expression as cardiac myocytes mature from embryonic to adult stages. To date, many studies have investigated individual effects of embryonic vs. cardiac isoforms of either TnI or MHC on cardiac muscle function and contractile dynamics. Thus, we sought to determine whether concomitant expression of the embryonic isoforms of both TnI and MHC had functional effects that were not previously observed. Adult transgenic (TG) mice that express the embryonic isoform of TnI, slow skeletal TnI (ssTnI), were treated with propylthiouracil (PTU) to revert MHC expression from adult (α-MHC) to embryonic (β-MHC) isoforms. Cardiac muscle fibres from these mice contained ∼80% β-MHC and ∼34% ssTnI of total MHC or TnI, respectively, allowing us to test the functional effects of ssTnI in the presence of β-MHC. Detergent-skinned cardiac muscle fibre bundles were used to study how the interplay between MHC and TnI modulate muscle length-mediated effect on crossbridge (XB) recruitment dynamics, Ca(2+)-activated tension, and ATPase activity. One major finding was that the model-predicted XB recruitment rate (b) was enhanced significantly by ssTnI, and this speeding effect of ssTnI on XB recruitment rate was much greater (3.8-fold) when β-MHC was present. Another major finding was that the previously documented ssTnI-mediated increase in myofilament Ca(2+) sensitivity (pCa(50)) was blunted when β-MHC was present. ssTnI expression increased pCa(50) by 0.33 in α-MHC fibres, whereas ssTnI increased pCa(50) by only 0.05 in β-MHC fibres. Our study provides new evidence for significant interplay between MHC and TnI isoforms that is essential for tuning cardiac contractile function. Thus, MHC-TnI interplay may provide a developmentally dependent mechanism to enhance XB recruitment dynamics at a time when Ca(2+)-handling mechanisms are underdeveloped, and to prevent excessive ssTnI-dependent inotropy (increased Ca(2+) sensitivity) in the embryonic myocardium.
Collapse
Affiliation(s)
- Steven J Ford
- Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology (VCAPP), Washington State University, Pullman, WA 99164, USA.
| | | |
Collapse
|
6
|
Alderman SL, Klaiman JM, Deck CA, Gillis TE. Effect of cold acclimation on troponin I isoform expression in striated muscle of rainbow trout. Am J Physiol Regul Integr Comp Physiol 2012; 303:R168-76. [DOI: 10.1152/ajpregu.00127.2012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In vertebrates each of the three striated muscle types (fast skeletal, slow skeletal, and cardiac) contain distinct isoforms of a number of different contractile proteins including troponin I (TnI). The functional characteristics of these proteins have a significant influence on muscle function and contractility. The purpose of this study was to characterize which TnI gene and protein isoforms are expressed in the different muscle types of rainbow trout ( Oncorhynchus mykiss) and to determine whether isoform expression changes in response to cold acclimation (4°C). Semiquantitative real-time PCR was used to characterize the expression of seven different TnI genes. The sequence of these genes, cloned from Atlantic salmon ( Salmo salar) and rainbow trout, were obtained from the National Center for Biotechnology Information databases. One-dimensional gel electrophoresis and tandem mass spectrometry were used to identify the TnI protein isoforms expressed in each muscle type. Interestingly, the results indicate that each muscle type expresses the gene transcripts of up to seven TnI isoforms. There are significant differences, however, in the expression pattern of these genes between muscle types. In addition, cold acclimation was found to increase the expression of specific gene transcripts in each muscle type. The proteomics analysis demonstrates that fast skeletal and cardiac muscle contain three TnI isoforms, whereas slow skeletal muscle contains four. No other vertebrate muscle to date has been found to express as many TnI protein isoforms. Overall this study underscores the complex molecular composition of teleost striated muscle and suggests there is an adaptive value to the unique TnI profiles of each muscle type.
Collapse
Affiliation(s)
- Sarah L. Alderman
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada
| | - Jordan M. Klaiman
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada
| | - Courtney A. Deck
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada
| | - Todd E. Gillis
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada
| |
Collapse
|
7
|
Posterino GS, Dunn SL, Botting KJ, Wang W, Gentili S, Morrison JL. Changes in cardiac troponins with gestational age explain changes in cardiac muscle contractility in the sheep fetus. J Appl Physiol (1985) 2011; 111:236-43. [PMID: 21493721 DOI: 10.1152/japplphysiol.00067.2011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The development of the adult cardiac troponin complex in conjunction with changes in cardiac function and cardiomyocyte binucleation has not been systematically characterized during fetal life in a species where maturation of the cardiomyocytes occurs prenatally as it does in the human. The aim of this study was to correlate the expression of each of the major adult troponin isoforms (T, I, and C) during late gestation (term of 150 days) to changes in both Ca(2+) sensitivity and maximum Ca(2+)-activated force of the contractile apparatus and the maturation of cardiomyocytes. The percentage of mononucleated cardiomyocytes in the right ventricle decreased with gestational age to 46% by 137-142 days of gestation. The length of binucleated cardiomyocytes did not change with gestational age, but the length of binucleated cardiomyocytes relative to heart weight decreased with gestational age. There was no change in the expression of adult cardiac troponin T with increasing gestation. The contractile apparatus was significantly more sensitive to Ca(2+) at 90 days compared with either 132 or 139 days of gestation, consistent with an ∼30% increase in the expression of adult cardiac troponin I between 90 and 110 days of gestation. Maximum Ca(2+)-activated force significantly increased from 90 days compared with 130 days consistent with an increase of ∼40% in cardiac troponin C protein expression. These data show that increased adult cardiac troponin I and C protein expression across late gestation is consistent with reduced Ca(2+) sensitivity and increased maximum Ca(2+)-activated force. Furthermore, changes in cardiac troponin C, not I, protein expression track with the timing of cardiomyocyte binucleation.
Collapse
Affiliation(s)
- Giuseppe Saverio Posterino
- Department of Zoology, School of Life Sciences, Faculty of Science and Technology, LaTrobe University, Melbourne, VIC, Australia.
| | | | | | | | | | | |
Collapse
|
8
|
Nomura RMY, Cabar FR, Costa VN, Miyadahira S, Zugaib M. Cardiac troponin T as a biochemical marker of cardiac dysfunction and ductus venosus Doppler velocimetry. Eur J Obstet Gynecol Reprod Biol 2009; 147:33-6. [DOI: 10.1016/j.ejogrb.2009.06.029] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2009] [Revised: 05/25/2009] [Accepted: 06/30/2009] [Indexed: 11/16/2022]
|
9
|
Yuan C, Sheng Q, Tang H, Li Y, Zeng R, Solaro RJ. Quantitative comparison of sarcomeric phosphoproteomes of neonatal and adult rat hearts. Am J Physiol Heart Circ Physiol 2008; 295:H647-56. [PMID: 18552161 DOI: 10.1152/ajpheart.00357.2008] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Neonatal hearts respond to stress and function in an environment quite different from adult hearts. There is evidence that these functional differences not only reflect modifications in the abundance and isoforms of sarcomeric proteins but also in the modulation of sarcomeric protein phosphorylation. Yet our understanding of changes in sarcomeric protein phosphorylation in development is incomplete. In the experiments reported here, we first quantified the intact sarcomeric protein phosphorylation status between neonatal and adult rat hearts by employing comparative two-dimensional (2-D) gel electrophoresis in conjunction with phosphoprotein-specific staining. Subsequently, we measured phosphorylation changes at the peptide level by employing high-resolution linear ion trap-Fourier transform (LTQ-FT) mass spectrometry analysis of titanium dioxide-enriched phosphopeptides differentially labeled with (16)O/(18)O during in-gel digestion. We also employed Western blot analysis using phosphorylation site-specific antibodies to measure phosphorylation changes. Our data demonstrated the novel finding that phosphorylation levels of myosin-binding protein C (MyBP-C) at Ser(295) and Ser(315) as well as tropomyosin at Ser(283) increased, whereas phosphorylation levels of MyBP-C at Ser(320) and myosin light chain 2 at Ser(15) decreased in neonatal hearts compared with the same sites in adult hearts. Although our data highlight the significant challenges in understanding relations between protein phosphorylation and cardiac function, they do support the hypothesis that developmental changes in the modulation of protein are functionally significant and correlate with the prevailing physiological state.
Collapse
Affiliation(s)
- Chao Yuan
- Department of Physiology and Biophysics, UIC, Chicago, IL 60612, USA
| | | | | | | | | | | |
Collapse
|
10
|
Westfall MV, Metzger JM. Single amino acid substitutions define isoform-specific effects of troponin I on myofilament Ca2+ and pH sensitivity. J Mol Cell Cardiol 2007; 43:107-18. [PMID: 17602701 PMCID: PMC2043486 DOI: 10.1016/j.yjmcc.2007.05.017] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2006] [Revised: 04/23/2007] [Accepted: 05/15/2007] [Indexed: 11/25/2022]
Abstract
Troponin I isoforms play a key role in determining myofilament Ca2+ sensitivity in cardiac muscle. The goal here was to identify domain clusters and residues that confer troponin I isoform-specific myofilament Ca2+ and pH sensitivities of contraction. Key domains/residues that contribute to troponin I isoform-specific Ca2+ and pH sensitivity were studied using gene transfer of a slow skeletal troponin I (ssTnI) template, with targeted cardiac troponin I (cTnI) residue substitutions. Substitutions in ssTnI with cognate cTnI residues R125Q, H132A, and V134E, studied both independently and together (ssTnIQAE), resulted in efficient stoichiometric replacement of endogenous myofilament cTnI in adult cardiac myocytes. In permeabilized myocytes, the pCa50 of tension ([Ca2+] required for half maximal force), and the acidosis-induced rightward shift of pCa50 were converted to the cTnI phenotype in myocytes expressing ssTnIQAE or ssTnIH132A, and there was no functionally additive effect of ssTnIQAE versus ssTnIH132A. Interestingly, only the acidosis-induced shift in Ca2+ sensitivity was comparable to cTnI in myocytes expressing ssTnIV134E, while ssTnIR125Q fully retained the ssTnI phenotype. An additional ssTnIN141H substitution, which lies within the same structural region of TnI as V134, produced a shift in myofilament Ca2+ sensitivity comparable to cTnI at physiological pH, while the acidic pH response was similar to the effect of wild-type ssTnI. Analysis of sarcomere shortening in intact adult cardiac myocytes was consistent with the force measurements. Targeted substitutions in the carboxyl portion of TnI produced residue-specific influences on myofilament Ca2+ and pH sensitivity of force and give new molecular insights into the TnI isoform dependence of myofilament function.
Collapse
Affiliation(s)
- Margaret V Westfall
- Department of Surgery, Cardiac Surgery Section, University of Michigan, 1150 W. Medical Center Drive, B560 MSRB II, Ann Arbor, MI 48109-0686, USA.
| | | |
Collapse
|
11
|
Krüger M, Kohl T, Linke WA. Developmental changes in passive stiffness and myofilament Ca2+sensitivity due to titin and troponin-I isoform switching are not critically triggered by birth. Am J Physiol Heart Circ Physiol 2006; 291:H496-506. [PMID: 16679402 DOI: 10.1152/ajpheart.00114.2006] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The giant protein titin, a major contributor to myocardial mechanics, is expressed in two main cardiac isoforms: stiff N2B (3.0 MDa) and more compliant N2BA (>3.2 MDa). Fetal hearts of mice, rats, and pigs express a unique N2BA isoform (∼3.7 MDa) but no N2B. Around birth the fetal N2BA titin is replaced by smaller-size N2BA isoforms and N2B, which predominates in adult hearts, stiffening their sarcomeres. Here we show that perinatal titin-isoform switching and corresponding passive stiffness (STp) changes do not occur in the hearts of guinea pig and sheep. In these species the shift toward “adult” proportions of N2B isoform is almost completed by midgestation. The relative contributions of titin and collagen to STpwere estimated in force measurements on skinned cardiac muscle strips by selective titin proteolysis, leaving the collagen matrix unaffected. Titin-based STpcontributed between 42% and 58% to total STpin late-fetal and adult sheep/guinea pigs and adult rats. However, only ∼20% of total STpwas titin based in late-fetal rat. Titin-borne passive tension and the proportion of titin-based STpgenerally scaled with the N2B isoform percentage. The titin isoform transitions were correlated to a switch in troponin-I (TnI) isoform expression. In rats, fetal slow skeletal TnI (ssTnI) was replaced by adult carciac TnI (cTnI) shortly after birth, thereby reducing the Ca2+sensitivity of force development. In contrast, guinea pig and sheep coexpressed ssTnI and cTnI in fetal hearts, and skinned fibers from guinea pig showed almost no perinatal shift in Ca2+sensitivity. We conclude that TnI-isoform and titin-isoform switching and corresponding functional changes during heart development are not initiated by birth but are genetically programmed, species-specific regulated events.
Collapse
Affiliation(s)
- Martina Krüger
- Physiology and Biophysics Unit, Univ. of Muenster, Schlossplatz 5, D-48149 Muenster, Germany.
| | | | | |
Collapse
|
12
|
Adamcová M, Stĕrba M, Simůnek T, Potácová A, Popelová O, Gersl V. Myocardial regulatory proteins and heart failure. Eur J Heart Fail 2006; 8:333-42. [PMID: 16309957 DOI: 10.1016/j.ejheart.2005.09.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2004] [Revised: 07/01/2005] [Accepted: 09/22/2005] [Indexed: 10/25/2022] Open
Abstract
Cardiac troponin T (cTnT) and cardiac troponin I (cTnI) are considered to be the most specific and sensitive biochemical markers of myocardial damage. Troponins have been studied in a wide range of clinical settings, including heart failure; however, there are few data on the role of regulatory proteins in the pathogenesis of heart failure, although a few interesting hypotheses have been proposed. A considerable body of evidence favours the view that alteration of the myocardial thin filament is the primary event leading to defective contractility of the failing myocardium, while the changes in Ca(2+) handling are a compensatory response. A better understanding of the role of regulatory proteins under different physiological and pathological conditions could lead to new therapeutic approaches in heart failure. Recently, calcium sensitisation has been proposed as a novel method by which cardiac performance may be enhanced via an increase in the affinity of troponin C for calcium but without affecting intracellular calcium concentration. To date, the only calcium sensitizer used in clinical practice is levosimendan.
Collapse
Affiliation(s)
- Michaela Adamcová
- Department of Physiology, Faculty of Medicine in Hradec Králové, Charles University in Prague, Simkova 870, 500 38 Hradec Králové, Czech Republic.
| | | | | | | | | | | |
Collapse
|
13
|
Davis ME, Hsieh PCH, Takahashi T, Song Q, Zhang S, Kamm RD, Grodzinsky AJ, Anversa P, Lee RT. Local myocardial insulin-like growth factor 1 (IGF-1) delivery with biotinylated peptide nanofibers improves cell therapy for myocardial infarction. Proc Natl Acad Sci U S A 2006; 103:8155-60. [PMID: 16698918 PMCID: PMC1472445 DOI: 10.1073/pnas.0602877103] [Citation(s) in RCA: 422] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Strategies for cardiac repair include injection of cells, but these approaches have been hampered by poor cell engraftment, survival, and differentiation. To address these shortcomings for the purpose of improving cardiac function after injury, we designed self-assembling peptide nanofibers for prolonged delivery of insulin-like growth factor 1 (IGF-1), a cardiomyocyte growth and differentiation factor, to the myocardium, using a "biotin sandwich" approach. Biotinylated IGF-1 was complexed with tetravalent streptavidin and then bound to biotinylated self-assembling peptides. This biotin sandwich strategy allowed binding of IGF-1 but did not prevent self-assembly of the peptides into nanofibers within the myocardium. IGF-1 that was bound to peptide nanofibers activated Akt, decreased activation of caspase-3, and increased expression of cardiac troponin I in cardiomyocytes. After injection into rat myocardium, biotinylated nanofibers provided sustained IGF-1 delivery for 28 days, and targeted delivery of IGF-1 in vivo increased activation of Akt in the myocardium. When combined with transplanted cardiomyocytes, IGF-1 delivery by biotinylated nanofibers decreased caspase-3 cleavage by 28% and increased the myocyte cross-sectional area by 25% compared with cells embedded within nanofibers alone or with untethered IGF-1. Finally, cell therapy with IGF-1 delivery by biotinylated nanofibers improved systolic function after experimental myocardial infarction, demonstrating how engineering the local cellular microenvironment can improve cell therapy.
Collapse
Affiliation(s)
- Michael E. Davis
- *Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02139
| | - Patrick C. H. Hsieh
- *Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02139
| | - Tomosaburo Takahashi
- *Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02139
| | - Qing Song
- Division of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139; and
| | - Shuguang Zhang
- Division of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139; and
| | - Roger D. Kamm
- Division of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139; and
| | - Alan J. Grodzinsky
- Division of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139; and
| | - Piero Anversa
- Cardiovascular Research Institute, Department of Medicine, New York Medical College, Valhalla, NY 10595
| | - Richard T. Lee
- *Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02139
- Division of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139; and
- To whom correspondence should be addressed at:
Partners Research Facility, Room 280, 65 Landsdowne St., Cambridge, MA 02139. E-mail:
| |
Collapse
|
14
|
Abstract
While the remodeling process in myocardial failure involves changes in ventricular structure and performance, it is now appreciated that it is also associated with changes in thin filament composition and function. As is discussed, changes at the level thick filament may affect thin filament activation in heart failure. Alterations in actin, troponin and tropomyosin isoform composition do not appear to be significant factors in human heart failure. In contrast, proteolytic degradation of troponin subunits are likely to be playing a functional role in some forms of cardiomyopathy (e.g. ischemic). Finally, phosphorylation of troponin I and troponin T by kinases (most notably protein kinase C) substantially affect thin filament function in failing human myocardium. These findings indicate that functional deficits in thin filament function in failing myocardium are largely reversible and create the potential for future targeted therapies in the treatment of this deadly disease.
Collapse
Affiliation(s)
- Peter VanBuren
- Department of Medicine, College of Medicine, University of Vermont, VT 05405, USA.
| | | |
Collapse
|
15
|
Baar K, Birla R, Boluyt MO, Borschel GH, Arruda EM, Dennis RG. Self-organization of rat cardiac cells into contractile 3-D cardiac tissue. FASEB J 2004; 19:275-7. [PMID: 15574489 DOI: 10.1096/fj.04-2034fje] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The mammalian heart is not known to regenerate following injury. Therefore, there is great interest in developing viable tissue-based models for cardiac assist. Recent years have brought numerous advances in the development of scaffold-based models of cardiac tissue, but a self-organizing model has yet to be described. Here, we report the development of an in vitro cardiac tissue without scaffolding materials in the contractile region. Using an optimal concentration of the adhesion molecule laminin, a confluent layer of neonatal rat cardiomyogenic cells can be induced to self-organize into a cylindrical construct, resembling a papillary muscle, which we have termed a cardioid. Like endogenous heart tissue, cardioids contract spontaneously and can be electrically paced between 1 and 5 Hz indefinitely without fatigue. These engineered cardiac tissues also show an increased rate of spontaneous contraction (chronotropy), increased rate of relaxation (lusitropy), and increased force production (inotropy) in response to epinephrine. Cardioids have a developmental protein phenotype that expresses both alpha- and beta-tropomyosin, very low levels of SERCA2a, and very little of the mature isoform of cardiac troponin T.
Collapse
|
16
|
Gomes AV, Venkatraman G, Davis JP, Tikunova SB, Engel P, Solaro RJ, Potter JD. Cardiac Troponin T Isoforms Affect the Ca2+ Sensitivity of Force Development in the Presence of Slow Skeletal Troponin I. J Biol Chem 2004; 279:49579-87. [PMID: 15358779 DOI: 10.1074/jbc.m407340200] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In this study we investigated the physiological role of the cardiac troponin T (cTnT) isoforms in the presence of human slow skeletal troponin I (ssTnI). ssTnI is the main troponin I isoform in the fetal human heart. In reconstituted fibers containing the cTnT isoforms in the presence of ssTnI, cTnT1-containing fibers showed increased Ca(2+) sensitivity of force development compared with cTnT3- and cTnT4-containing fibers. The maximal force in reconstituted skinned fibers was significantly greater for the cTnT1 (predominant fetal cTnT isoform) when compared with cTnT3 (adult TnT isoform) in the presence of ssTnI. Troponin (Tn) complexes containing ssTnI and reconstituted with cTnT isoforms all yielded different maximal actomyosin ATPase activities. Tn complexes containing cTnT1 and cTnT4 (both fetal isoforms) had a reduced ability to inhibit actomyosin ATPase activity when compared with cTnT3 (adult isoform) in the presence of ssTnI. The rate at which Ca(2+) was released from site II of cTnC in the cTnI.cTnC complex (122/s) was 12.5-fold faster than for the ssTnI.cTnC complex (9.8/s). Addition of cTnT3 to the cTnI.cTnC complex resulted in a 3.6-fold decrease in the Ca(2+) dissociation rate from site II of cTnC. Addition of cTnT3 to the ssTnI.cTnC complex resulted in a 1.9-fold increase in the Ca(2+) dissociation rate from site II of cTnC. The rate at which Ca(2+) dissociated from site II of cTnC in Tn complexes also depended on the cTnT isoform present. However, the TnI isoforms had greater effects on the Ca(2+) dissociation rate of site II than the cTnT isoforms. These results suggest that the different N-terminal TnT isoforms would produce distinct functional properties in the presence of ssTnI when compared with cTnI and that each isoform would have a specific physiological role in cardiac muscle.
Collapse
Affiliation(s)
- Aldrin V Gomes
- Department of Molecular and Cellular Pharmacology, University of Miami School of Medicine, Miami, FL 33136, USA
| | | | | | | | | | | | | |
Collapse
|
17
|
|
18
|
|
19
|
Modulation of Thin Filament Activity in Long and Short Term Regulation of Cardiac Function. MOLECULAR CONTROL MECHANISMS IN STRIATED MUSCLE CONTRACTION 2002. [DOI: 10.1007/978-94-015-9926-9_9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
|
20
|
Arteaga GM, Palmiter KA, Leiden JM, Solaro RJ. Attenuation of length dependence of calcium activation in myofilaments of transgenic mouse hearts expressing slow skeletal troponin I. J Physiol 2000; 526 Pt 3:541-9. [PMID: 10922006 PMCID: PMC2270032 DOI: 10.1111/j.1469-7793.2000.t01-1-00541.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2000] [Accepted: 04/14/2000] [Indexed: 11/30/2022] Open
Abstract
We compared sarcomere length (SL) dependence of the Ca2+-force relation of detergent-extracted bundles of fibres dissected from the left ventricle of wild-type (WT) and transgenic mouse hearts expressing slow skeletal troponin I (ssTnI-TG). Fibre bundles from the hearts of the ssTnI-TG demonstrated a complete replacement of the cardiac troponin I (cTnI) by ssTnI. Compared to WT controls, ssTnI-TG fibre bundles were more sensitive to Ca2+ at both short SL (1.9 +/- 0.1 micrometer) and long SL (2.3 +/- 0.1 micrometer). However, compared to WT controls, the increase in Ca2+ sensitivity (change in half-maximally activating free Ca2+; DeltaEC50) associated with the increase in SL was significantly blunted in the ssTnI-TG myofilaments. Agents that sensitize the myofilaments to Ca2+ by promoting the actin-myosin reaction (EMD 57033 and CGP-48506) significantly reduced the length-dependent DeltaEC50 for Ca2+ activation, when SL in WT myofilaments was increased from 1.9 to 2.3 micrometer. Exposure of myofilaments to calmidazolium (CDZ), which binds to cTnC and increases its affinity for Ca2+, sensitized force developed by WT myofilaments to Ca2+ at SL 1.9 micrometer and desensitized the WT myofilaments at SL 2.3 micrometer. There were no significant effects of CDZ on ssTnI-TG myofilaments at either SL. Our results indicate that length-dependent Ca2+ activation is modified by specific changes in thin filament proteins and by agents that promote the actin-myosin interaction. Thus, these in vitro results provide a basis for using these models to test the relative significance of the length dependence of activation in situ.
Collapse
Affiliation(s)
- G M Arteaga
- Departments of Physiology and Biophysics and Pediatrics, College of Medicine, University of Illinois at Chicago, Chicago, IL 60612, USA
| | | | | | | |
Collapse
|
21
|
Haller C, Zehelein J, Remppis A, Müller-Bardorff M, Katus HA. Cardiac troponin T in patients with end-stage renal disease: absence of expression in truncal skeletal muscle. Clin Chem 1998. [DOI: 10.1093/clinchem/44.5.930] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
AbstractIn patients with end-stage renal disease (ESRD), the serum concentration of cardiac troponin T (cTnT) may be increased without cardiac ischemia. One reason for this unexplained increase could be the extracardiac expression of cTnT. However, truncal skeletal muscle biopsies of five patients with ESRD showed no evidence of the expression of either cTnT mRNA (reverse transcription-PCR) or protein (immunoblot, immunofluorescence). We also measured the serum concentration of cTnT in 97 patients with ESRD. The serum cTnT concentration determined in both first and second generation cTnT assays was significantly lower P <0.01 in patients with a low cardiac risk than in patients with positive indicators of coronary artery disease. The correlation between cTnT and indicators of coronary artery disease is consistent with the hypothesis that cTnT in the serum of patients with ESRD originates from the heart.
Collapse
Affiliation(s)
- Christlieb Haller
- Department of Medicine III, University of Heidelberg, 69115 Heidelberg, Germany
| | - Jörg Zehelein
- Department of Medicine III, University of Heidelberg, 69115 Heidelberg, Germany
| | - Andrew Remppis
- Department of Medicine II, University of Lübeck, 23538 Lübeck, Germany
| | | | - Hugo A Katus
- Department of Medicine II, University of Lübeck, 23538 Lübeck, Germany
| |
Collapse
|
22
|
|
23
|
Murphy AM, Thompson WR, Peng LF, Jones L. Regulation of the rat cardiac troponin I gene by the transcription factor GATA-4. Biochem J 1997; 322 ( Pt 2):393-401. [PMID: 9065755 PMCID: PMC1218204 DOI: 10.1042/bj3220393] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Troponin I is a thin-filament contractile protein expressed in striated muscle. There are three known troponin I genes which are expressed in a muscle-fibre-type-specific manner in mature animals. Although the slow skeletal troponin I isoform is expressed in fetal and neonatal heart, the cardiac isoform is restricted in its expression to the myocardium at all developmental stages. To study the regulation of this cardiac-specific and developmentally regulated gene in vitro, the rat cardiac troponin I gene was cloned. Transient transfection assays were performed with troponin I-luciferase fusion plasmids to characterize the regulatory regions of the gene. Proximal regions of the upstream sequence were sufficient to support high levels of expression of the reporter gene in cardiocytes and relatively low levels in other cell types. The highest luciferase activity in the cardiocytes was noted with a plasmid that included the region spanning -896 to +45 of the troponin I genomic sequence. Co-transfection of GATA-4, a recently identified cardiac transcription factor, with troponin I-luciferase constructs permitted high levels of luciferase expression in non-cardiac cells. Electrophoretic mobility-shift assays demonstrated specific binding of GATA-4 to oligonucleotides representative of multiple sites of the troponin I sequence. Mutation of a proximal GATA-4 DNA-binding site decreased transcriptional activation in transfected cardiocytes. These results indicate that the proximal cardiac troponin I sequence is sufficient to support high levels of cardiac-specific gene expression and that the GATA-4 transcription factor regulates troponin I-luciferase expression in vitro.
Collapse
Affiliation(s)
- A M Murphy
- Department of Pediatrics, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, U.S.A
| | | | | | | |
Collapse
|
24
|
Penefsky ZJ, Elwood JC. Mechanical responses of chromium-deficient developing rat heart. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. PART A, PHYSIOLOGY 1996; 114:175-87. [PMID: 8925433 DOI: 10.1016/0300-9629(95)02126-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Mechanical responses were compared between controls, developing Sprague-Dawley rat papillary muscle and age-matched weanlings fed with Torula yeast, a food source deficient in chromium. At 8 weeks postnatal, deficient rats differed in significant ways from their normal counterparts. Deficient rats in contrast to controls weighed less, their interval-force (I-F) relationship was more negative and their inotropic response to high calcium concentrations was greater. At this time, however, deficient and control rats responded equally to alpha (phenylephrine) and beta (isoproterenol) agonists. At 10 weeks of age, the controls exhibited a less negative I-F and a negative inotropic response to high calcium concentrations while the response to alpha and beta agonists was unchanged. In contrast, at 10 weeks of age, the chromium-deficient rats exhibited a highly negative I-F response and significant inotropic response to high calcium concentrations. The response of the deficient hearts to beta-agonists diminished. At 13 weeks postnatal, control hearts showed only a 10-15% negative I-F response, a persistent response to catecholamines and negative inotropic responses to high calcium concentrations. In deficient hearts, the negative I-F response was reduced and the response to beta-agonists was further diminished but a positive inotropic response to phenylephrine and high calcium concentrations persisted. These observations in deficient animals are explained in terms of a retarded development of the calcium handling elements in the heart and a lack of an insulin-like growth factor.
Collapse
Affiliation(s)
- Z J Penefsky
- Department of Pharmacology, SUNY Health Science Center, Syracuse 13210, USA
| | | |
Collapse
|