scholarly journals Evaluation of laser induced sarcomere micro-damage: Role of damage extent and location in cardiomyocytes

PLoS ONE ◽  
2021 ◽  
Vol 16 (6) ◽  
pp. e0252346
Author(s):  
Dominik Müller ◽  
Thorben Klamt ◽  
Lara Gentemann ◽  
Alexander Heisterkamp ◽  
Stefan Michael Klaus Kalies
Keyword(s):  
Femtosecond Laser ◽  
Heart Function ◽  
Neonatal Rat ◽  
Cellular Mechanisms ◽  
Important Indicator ◽  
Rat Cardiomyocytes ◽  
Propagation Function ◽  
Entire Cell ◽  
Damage Extent ◽  
Extent Of Damage

Whereas it is evident that a well aligned and regular sarcomeric structure in cardiomyocytes is vital for heart function, considerably less is known about the contribution of individual elements to the mechanics of the entire cell. For instance, it is unclear whether altered Z-disc elements are the reason or the outcome of related cardiomyopathies. Therefore, it is crucial to gain more insight into this cellular organization. This study utilizes femtosecond laser-based nanosurgery to better understand sarcomeres and their repair upon damage. We investigated the influence of the extent and the location of the Z-disc damage. A single, three, five or ten Z-disc ablations were performed in neonatal rat cardiomyocytes. We employed image-based analysis using a self-written software together with different already published algorithms. We observed that cardiomyocyte survival associated with the damage extent, but not with the cell area or the total number of Z-discs per cell. The cell survival is independent of the damage position and can be compensated. However, the sarcomere alignment/orientation is changing over time after ablation. The contraction time is also independent of the extent of damage for the tested parameters. Additionally, we observed shortening rates between 6–7% of the initial sarcomere length in laser treated cardiomyocytes. This rate is an important indicator for force generation in myocytes. In conclusion, femtosecond laser-based nanosurgery together with image-based sarcomere tracking is a powerful tool to better understand the Z-disc complex and its force propagation function and role in cellular mechanisms.

Abstract 419: Stim1 is Associated With Calcium Microdomains That are Required for Myofilament Remodeling and Signaling During Cardiac Hypertrophy

2015 ◽  
Vol 117 (suppl_1) ◽  
Author(s):  
Cory Parks ◽  
Ryan D Sullivan ◽  
Salvatore Mancarella
Keyword(s):  
Cardiac Hypertrophy ◽  
Heart Function ◽  
Cardiac Contractility ◽  
Pressure Overload ◽  
Left Ventricular ◽  
Neonatal Rat ◽  
Excitable Cells ◽  
Rat Cardiomyocytes ◽  
Cell Contractility

Stromal Interaction Protein 1 (STIM1) is the intracellular component of the store operated calcium channels. It is a ubiquitous Ca2+ sensor, prevalently located in the sarcoplasmic reticulum. In non-excitable cells, STIM1 is a key element in the generation of Ca2+signals that lead to gene expression and cell proliferation. A growing body of literature now suggests that STIM1 is important for normal heart function and plays a key role in the development of pathological cardiac hypertrophy. However, the precise mechanisms involving STIM1 and the Ca2+ signaling in excitable cells are not clearly established. We show that in neonatal rat cardiomyocytes, the spatial properties of STIM1-dependent Ca2+ signals determine restricted Ca2+ microdomains that regulate myofilaments remodeling and spatially segregated activation of pro-hypertrophic factors. Indeed, in vivo data obtained from an inducible cardiac restricted STIM1 knockout mouse, exhibited left ventricular dilatation associated with reduced cardiac contractility, which was corroborated by impaired single cell contractility. Furthermore, mice lacking STIM1 showed less adverse structural remodeling in response to pathological pressure overload-induced cardiac hypertrophy (transverse aortic constriction, TAC). We further show that the Ca2+ pool associated with STIM1 is the ON switch for extracellular signal-regulated kinase (ERK1/2)-mediated cytoplasm to nucleus signaling. These results highlight how STIM1-dependent Ca2+ microdomains have a major impact on intracellular Ca2+ homeostasis, cytoskeletal remodeling, signaling and cardiac function, even when excitation-contraction coupling is present.

Necrostatin-1 Analog DIMO Exerts Cardioprotective Effect against Ischemia Reperfusion Injury by Suppressing Necroptosis via Autophagic Pathway in Rats

Pharmacology ◽  
2021 ◽  
Vol 106 (3-4) ◽  
pp. 189-201
Author(s):  
Shigang Qiao ◽  
Wen-jie Zhao ◽  
Huan-qiu Li ◽  
Gui-zhen Ao ◽  
Jian-zhong An ◽  
...  
Keyword(s):  
Cell Death ◽  
Ischemia Reperfusion Injury ◽  
Myocardial Infarct ◽  
Ischemia Reperfusion ◽  
Glucose Deprivation ◽  
Neonatal Rat ◽  
Ligand Docking ◽  
Autophagic Flux ◽  
Myocardial Infarct Size ◽  
Rat Cardiomyocytes

Aim: It has been reported that necrostatin-1 (Nec-1) is a specific necroptosis inhibitor that could attenuate programmed cell death induced by myocardial ischemia/reperfusion (I/R) injury. This study aimed to observe the effect and mechanism of novel Nec-1 analog (Z)-5-(3,5-dimethoxybenzyl)-2-imine-1-methylimidazolin-4-1 (DIMO) on myocardial I/R injury. Methods: Male SD rats underwent I/R injury with or without different doses of DIMO (1, 2, or 4 mg/kg) treatment. Isolated neonatal rat cardiomyocytes were subjected to oxygen-glucose deprivation/reoxygenation (OGD/R) treatment with or without DIMO (0.1, 1, 10, or 100 μM). Myocardial infarction was measured by TTC staining. Cardiomyocyte injury was assessed by lactate dehydrogenase assay (LDH) and flow cytometry. Receptor-interacting protein 1 kinase (RIP1K) and autophagic markers were detected by co-immunoprecipitation and Western blotting analysis. Molecular docking of DIMO into the ATP binding site of RIP1K was performed using GLIDE. Results: DIMO at doses of 1 or 2 mg/kg improved myocardial infarct size. However, the DIMO 4 mg/kg dose was ineffective. DIMO at the dose of 0.1 μM decreased LDH leakage and the ratio of PI-positive cells followed by OGD/R treatment. I/R or OGD/R increased RIP1K expression and in its interaction with RIP3K, as well as impaired myocardial autophagic flux evidenced by an increase in LC3-II/I ratio, upregulated P62 and Beclin-1, and activated cathepsin B and L. In contrast, DIMO treatment reduced myocardial cell death and reversed the above mentioned changes in RIP1K and autophagic flux caused by I/R and OGD/R. DIMO binds to RIP1K and inhibits RIP1K expression in a homology modeling and ligand docking. Conclusion: DIMO exerts cardioprotection against I/R- or OGD/R-induced injury, and its mechanisms may be associated with the reduction in RIP1K activation and restoration impaired autophagic flux.

scholarly journals Id2 Represses Aldosterone-Stimulated Cardiac T-Type Calcium Channels Expression

2021 ◽  
Vol 22 (7) ◽  
pp. 3561
Author(s):  
Jumpei Ito ◽  
Tomomi Minemura ◽  
Sébastien Wälchli ◽  
Tomoaki Niimi ◽  
Yoshitaka Fujihara ◽  
...  
Keyword(s):  
Transcriptional Repressor ◽  
Neonatal Rat ◽  
Protective Mechanism ◽  
Pathological State ◽  
Rat Cardiomyocytes ◽  
Adult Mice ◽  
Spontaneous Action ◽  
Sirna Knockdown ◽  
Spontaneous Action Potentials ◽  
Ca2 Channels

Aldosterone excess is a cardiovascular risk factor. Aldosterone can directly stimulate an electrical remodeling of cardiomyocytes leading to cardiac arrhythmia and hypertrophy. L-type and T-type voltage-gated calcium (Ca2+) channels expression are increased by aldosterone in cardiomyocytes. To further understand the regulation of these channels expression, we studied the role of a transcriptional repressor, the inhibitor of differentiation/DNA binding protein 2 (Id2). We found that aldosterone inhibited the expression of Id2 in neonatal rat cardiomyocytes and in the heart of adult mice. When Id2 was overexpressed in cardiomyocytes, we observed a reduction in the spontaneous action potentials rate and an arrest in aldosterone-stimulated rate increase. Accordingly, Id2 siRNA knockdown increased this rate. We also observed that CaV1.2 (L-type Ca2+ channel) or CaV3.1, and CaV3.2 (T-type Ca2+ channels) mRNA expression levels and Ca2+ currents were affected by Id2 presence. These observations were further corroborated in a heart specific Id2- transgenic mice. Taken together, our results suggest that Id2 functions as a transcriptional repressor for L- and T-type Ca2+ channels, particularly CaV3.1, in cardiomyocytes and its expression is controlled by aldosterone. We propose that Id2 might contributes to a protective mechanism in cardiomyocytes preventing the presence of channels associated with a pathological state.

Mechanical activity in heart regulates translation of α-myosin heavy chain mRNA but not its localization

1999 ◽  
Vol 276 (6) ◽  
pp. H2013-H2019 ◽  
Author(s):  
Gordana Nikcevic ◽  
Maria C. Heidkamp ◽  
Merja Perhonen ◽  
Brenda Russell
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Mrna Translation ◽  
Neonatal Rat ◽  
Mechanical Activity ◽  
Mrna Levels ◽  
Rat Cardiomyocytes ◽  
Significant Difference ◽  
Polysomal Fraction ◽  
Mechanical Transduction

Mechanical inactivity depresses protein expression in cardiac muscle tissue and results in atrophy. We explore the mechanical transduction mechanism in spontaneously beating neonatal rat cardiomyocytes expressing the α-myosin heavy chain (α-MyHC) isoform by interfering with cross-bridge function [2,3-butanedione monoxime (BDM), 7.5 mM] without affecting cell calcium. The polysome content and α-MyHC mRNA levels in fractions from a sucrose gradient were analyzed. BDM treatment blocked translation at initiation (162 ± 12% in the nonpolysomal RNA fraction and 43 ± 6% in the polysomal fraction, relative to control as 100%; P < 0.05). There was an increase in α-MyHC mRNA from the nonpolysomal fraction (120.5 ± 7.7%; P < 0.05 compared with control) with no significant change in the heavy polysomes. In situ hybridization of α-MyHC mRNA was used to estimate message abundance as a function of the distance from the nucleus. The mRNA was dispersed through the cytoplasm in spontaneously beating cells as well as in BDM-treated cells (no significant difference). We conclude that direct inhibition of contractile machinery, but not calcium, regulates initiation of α-MyHC mRNA translation. However, calcium, not pure mechanical signals, appears to be important for message localization.

Damage Quantitative Investigation of Beam Structure Based on Changing Ratio of Modal Curvature

2011 ◽  
Vol 255-260 ◽  
pp. 654-658
Author(s):  
Ji Ping Ge
Keyword(s):  
Linear Increase ◽  
Beam Structure ◽  
Quantitative Investigation ◽  
Supporting System ◽  
Damage Recognition ◽  
Modal Curvature ◽  
Damage Extent ◽  
Extent Of Damage ◽  
The Relationship

The changing ratio of modal curvature is proposed for damage recognition, and its ability of damage localization and damage quantitative has been studied in this paper. For testing the effect of damage recognition, two research parameters, the different section rigidity and the scope of damages, are included. And changing rules of the index with structure rigidity, constraints, and structure supporting system have been studied at the same time. The numerical analysis results indicated: The relation of linear increase exists between the changing ratio of modal curvature and the extent of damage, the changing slope of the index is bigger with the increase of damage extent; The boundary condition and the structure supporting system will affect the value of index; In the view of one special structure, case study should be carried to establish the relationship between value of index and the extent of damage.

Cross-bridge cycling gives rise to spatiotemporal heterogeneity of dynamic subcellular mechanics in cardiac myocytes probed with atomic force microscopy

2010 ◽  
Vol 298 (3) ◽  
pp. H853-H860 ◽  
Author(s):  
Evren U. Azeloglu ◽  
Kevin D. Costa
Keyword(s):  
Contractile Activity ◽  
Major Axis ◽  
Neonatal Rat ◽  
Pharmacological Treatments ◽  
Rat Cardiomyocytes ◽  
Force Microscopy ◽  
Cross Bridge ◽  
Apparent Modulus ◽  
Atomic Force ◽  
And Function

To study how the dynamic subcellular mechanical properties of the heart relate to the fundamental underlying process of actin-myosin cross-bridge cycling, we developed a novel atomic force microscope elastography technique for mapping spatiotemporal stiffness of isolated, spontaneously beating neonatal rat cardiomyocytes. Cells were indented repeatedly at a rate close but unequal to their contractile frequency. The resultant changes in pointwise apparent elastic modulus cycled at a predictable envelope frequency between a systolic value of 26.2 ± 5.1 kPa and a diastolic value of 7.8 ± 4.1 kPa at a representative depth of 400 nm. In cells probed along their major axis, spatiotemporal changes in systolic stiffness displayed a heterogeneous pattern, reflecting the banded sarcomeric structure of underlying myofibrils. Treatment with blebbistatin eliminated contractile activity and resulted in a uniform apparent modulus of 6.5 ± 4.8 kPa. This study represents the first quantitative dynamic mechanical mapping of beating cardiomyocytes. The technique provides a means of probing the micromechanical effects of disease processes and pharmacological treatments on beating cardiomyocytes, providing new insights and relating subcellular cardiac structure and function.

Oxidative stress enhances phosphorylation of p53 in neonatal rat cardiomyocytes

2007 ◽  
Vol 303 (1-2) ◽  
pp. 167-174 ◽  
Author(s):  
Xilin Long ◽  
Michael J. Goldenthal ◽  
José Marín-García
Keyword(s):  
Oxidative Stress ◽  
Neonatal Rat ◽  
Rat Cardiomyocytes ◽  
Neonatal Rat Cardiomyocytes
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