Myoseverin disrupts sarcomeric organization in myocytes: An effect independent of microtubule assembly inhibition

Ng, Dominic C. H.; Gebski, Bijanka L.; Grounds, Miranda D.; Bogoyevitch, Marie A.

doi:10.1002/cm.20242

Cited by 9 publications

(5 citation statements)

References 40 publications

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“…Immunofluorescence Confocal Microscopy of NRVM and Heart Sections-NRVM and heart sections (8 m) from PI3K transgenic mice were analyzed by immunofluorescence staining with antibodies to ␣-actinin (Sigma-Aldrich), phalloidin (FITC-conjugates, Molecular Probes), DAPI, and Cy2/Cy3-conjugated secondary antibodies (Chemicon) as described previously (18,22). Prior to staining, hearts from caPI3K, dnPI3K, and Ntg mice were fixed in HistoChoice tissue fixative (Amersco) for 4 h at 4°C and then frozen in Tissue-Tek O.C.T TM compound (Sakura Finetechnical).…”

Section: Methodsmentioning

confidence: 99%

Phosphoinositide 3-Kinase (PI3K(p110α)) Directly Regulates Key Components of the Z-disc and Cardiac Structure

Waardenberg

Bernardo

et al. 2011

Journal of Biological Chemistry

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Maintenance of cardiac structure and Z-disc signaling are key factors responsible for protecting the heart in a setting of stress, but how these processes are regulated is not well defined. We recently demonstrated that PI3K(p110␣) protects the heart against myocardial infarction. The aim of this study was to determine whether PI3K(p110␣) directly regulates components of the Z-disc and cardiac structure. To address this question, a unique three-dimensional virtual muscle model was applied to gene expression data from transgenic mice with increased or decreased PI3K(p110␣) activity under basal conditions (sham) and in a setting of myocardial infarction to display the location of structural proteins. Key findings from this analysis were then validated experimentally. The three-dimensional virtual muscle model visually highlighted reciprocally regulated transcripts associated with PI3K activation that encoded key components of the Z-disc and costamere, including melusin. Studies were performed to assess whether PI3K and melusin interact in the heart. Here, we identify a novel melusin-PI3K interaction that generates lipid kinase activity. The direct impact of PI3K(p110␣) on myocyte structure was assessed by treating neonatal rat ventricular myocytes with PI3K(p110␣) inhibitors and examining the myofiber morphology of hearts from PI3K transgenic mice. Results demonstrate that PI3K is critical for myofiber maturation and Z-disc alignment. In summary, PI3K regulates the expression of genes essential for cardiac structure and Z-disc signaling, interacts with melusin, and is critical for Z-disc alignment.An important question in cardiac biology is what makes one heart stronger, or more capable of resisting stress, than another. Maintenance of cardiac structure and Z-disc signaling are considered key factors responsible for protecting the heart in a setting of stress. Mutations of genes encoding proteins of the costamere and Z-disc have been linked with cardiomyopathies in animals and humans (1, 2). Costameres are specialized membrane junctions that physically connect the Z-disc to the basal lamina outside of the cell. The Z-disc is well recognized for its role in maintaining structural integrity and, more recently, has emerged as a "hot spot" or nodal hub of cardiomyocyte signaling, converting mechanical signals into chemical signals, leading to a transcriptional response and induction of a cardiac phenotype such as hypertrophy (1). Despite progress in this area, the mechanisms responsible for regulating components of the costamere and Z-disc are not well defined (2).The p110␣ isoform of phosphoinositide 3-kinase (PI3K-(p110␣)/PIK3CA) has cardioprotective properties (3). We recently demonstrated that cardiac expression of a constitutively active (ca) 3 PI3K transgene (increased PI3K activity) provided protection in a mouse model of myocardial infarction (MI), whereas a reduction in cardiac PI3K activity (utilizing a dominant negative (dn) PI3K transgene) accelerated the progression of heart failure (4). This makes target...

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Section: Methodsmentioning

confidence: 99%

Phosphoinositide 3-Kinase (PI3K(p110α)) Directly Regulates Key Components of the Z-disc and Cardiac Structure

Waardenberg

Bernardo

et al. 2011

Journal of Biological Chemistry

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“…The direct participation of microtubules in myofibrillogenesis has been challenged, however, by several groups. For instance, treatment of myoblasts with myoseverin, a drug that depolymerizes microtubules, does affect both myofibrils and microtubules, but upon removal of myoseverin, myofibrils could be formed even in the absence of microtubules [67]. In the conditions used, treatment with nocodazole disassembled microtubules but did not interfere with myofibrils.…”

Section: Microtubulesmentioning

confidence: 99%

Cytoskeleton and Adhesion in Myogenesis

Costa

2014

ISRN Developmental Biology

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The function of muscle is to contract, which means to exert force on a substrate. The adaptations required for skeletal muscle differentiation, from a prototypic cell, involve specialization of housekeeping cytoskeletal contracting and supporting systems into crystalline arrays of proteins. Here I discuss the changes that all three cytoskeletal systems (microfilaments, intermediate filaments, and microtubules) undergo through myogenesis. I also discuss their interaction, through the membrane, to extracellular matrix and to other cells, where force will be exerted during contraction. The three cytoskeletal systems are necessary for the muscle cell and must exert complementary roles in the cell. Muscle is a responsive system, where structure and function are integrated: the structural adaptations it undergoes depend on force production. In this way, the muscle cytoskeleton is a portrait of its physiology. I review the cytoskeletal proteins and structures involved in muscle function and focus particularly on their role in myogenesis, the process by which this incredible muscle machine is made. Although the focus is on skeletal muscle, some of the discussion is applicable to cardiac and smooth muscle.

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“…Microtubule densities (pixels/ m 2 ) were determined by defining cell borders using phalloidin-stained actin filaments as a template. Phalloidin-TRITC staining of contractile filaments was also used to exclude nonmyocytes, which typically exhibit faint, non-striated linear stress fibers with actin staining (27). The defined regions were then transferred to tubulin co-stained images and pixel intensity and cell area (m 2 ) measured (supplemental Fig.…”

Section: Methodsmentioning

confidence: 99%

“…We have previously shown that hypertrophy of these cells is accompanied by an enhanced MT network (27). In this study, we investigated tubulin changes in cardiac myoyctes following 24 h exposure to the ␣-adrenergic agonist phenylephrine (PE) or the IL6 family cytokines, LIF or OSM.…”

Section: Il6 Family Cytokines Induce Mt Stabilization In Cardiac Myocmentioning

confidence: 99%

Opposing Actions of Extracellular Signal-regulated Kinase (ERK) and Signal Transducer and Activator of Transcription 3 (STAT3) in Regulating Microtubule Stabilization during Cardiac Hypertrophy

Yeap

et al. 2011

Journal of Biological Chemistry

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Excessive proliferation and stabilization of the microtubule (MT) array in cardiac myocytes can accompany pathological cardiac hypertrophy, but the molecular control of these changes remains poorly characterized. In this study, we examined MT stabilization in two independent murine models of heart failure and revealed increases in the levels of post-translationally modified stable MTs, which were closely associated with STAT3 activation. To explore the molecular signaling events contributing to control of the cardiac MT network, we stimulated cardiac myocytes with an ␣-adrenergic agonist phenylephrine (PE), and observed increased tubulin content without changes in detyrosinated (glutubulin) stable MTs. In contrast, the hypertrophic interleukin-6 (IL6) family cytokines increased both the glu-tubulin content and glu-MT density. When we examined a role for ERK in regulating cardiac MTs, we showed that the MEK/ERK-inhibitor U0126 increased glu-MT density in either control cardiac myocytes or following exposure to hypertrophic agents. Conversely, expression of an activated MEK1 mutant reduced glu-tubulin levels. Thus, ERK signaling antagonizes stabilization of the cardiac MT array. In contrast, inhibiting either JAK2 with AG490, or STAT3 signaling with Stattic or siRNA knockdown, blocked cytokine-stimulated increases in glu-MT density. Furthermore, the expression of a constitutively active STAT3 mutant triggered increased glu-MT density in the absence of hypertrophic stimulation. Thus, STAT3 activation contributes substantially to cytokine-stimulated glu-MT changes. Taken together, our results highlight the opposing actions of STAT3 and ERK pathways in the regulation of MT changes associated with cardiac myocyte hypertrophy.In cardiac myocytes, the microtubule (MT) 5 array comprises a major cytoskeletal element. MT organization changes between phases of assembly/disassembly with either fast (dynamic) or slow (stable) kinetics. MT stability can be regulated through direct association and regulation by numerous proteins such as MT-associated proteins (MAPs), plus-end tracking proteins (ϩTIPs) and tubulin-sequestering negative regulators of MT assembly (e.g. stathmins) (1-3). In turn, these direct modulators of MT stability are regulated by multisite phosphorylation by various kinases thus linking changes in MT dynamics with extracellular stimuli (2, 3). Furthermore, once assembled, tubulin polymers are modified by the addition of acetyl groups on Lys-40 (acetyl-tubulin) and the reversible removal of tyrosine from the ␣-tubulin C terminus (named glu-tubulin for the penultimate glutamate revealed) (4, 5). Post-translational modification of tubulin occurs as a direct function of the time a tubulin heterodimer spends in the polymerized state and therefore reports on MT age. Although not directly contributing to the stabilization of MTs per se, these modifications are markers of stabilized MTs that turnover slowly. In neurons, protein kinases such as the c-Jun N-terminal kinases and microtubule affinity-regulating kinases h...

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Myoseverin disrupts sarcomeric organization in myocytes: An effect independent of microtubule assembly inhibition

Cited by 9 publications

References 40 publications

Phosphoinositide 3-Kinase (PI3K(p110α)) Directly Regulates Key Components of the Z-disc and Cardiac Structure

Phosphoinositide 3-Kinase (PI3K(p110α)) Directly Regulates Key Components of the Z-disc and Cardiac Structure

Cytoskeleton and Adhesion in Myogenesis

Opposing Actions of Extracellular Signal-regulated Kinase (ERK) and Signal Transducer and Activator of Transcription 3 (STAT3) in Regulating Microtubule Stabilization during Cardiac Hypertrophy

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