References of "Maass, A"
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See detailExpression of the plasma membrane Ca2+-ATPase in myogenic cells.
Hammes, A.; Oberdorf-Maass, S.; Jenatschke, S. et al

in The Journal of biological chemistry (1996), 271(48), 30816-22

To study the physiological function of the plasma membrane calmodulin-dependent calcium ATPase (PMCA) in intact cells, L6 myogenic cell lines stably overexpressing the human PMCA isoform 4CI (= human PMCA ... [more ▼]

To study the physiological function of the plasma membrane calmodulin-dependent calcium ATPase (PMCA) in intact cells, L6 myogenic cell lines stably overexpressing the human PMCA isoform 4CI (= human PMCA isoform 4b) were generated. Several independent L6 clones and controls stably transfected with the empty expression vector were analyzed in detail. The resting cytosolic calcium level in hPMCA4CI-overexpressing muscle cells (measured by the Fura-2 method) was significantly reduced by 20-30% compared with controls. This was shown in a cytosolic window of 1322 single cells (p < 0.01). Furthermore, the differentiation process of these cells was remarkably accelerated compared with control myoblasts and parental nontransfected L6 cells as assessed by multinucleated myotube formation and creatine phosphokinase activity elevation. After 4 and 6 days of differentiation, PMCA-overexpressing L6 cells from four independent clones displayed a 3- and 4-fold higher creatine phosphokinase activity compared with controls (n = 5, p < 0.02). These results may extend the concept of the function of the PMCA from simple prevention of calcium overload to an active involvement in intracellular calcium regulation with potentially important consequences for cellular functions. [less ▲]

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See detailUse of antisense oligonucleotides for selective inhibition of gene expression in cardiomyocytes
Neyses, Ludwig UL; Blaufuss, B; Kubisch, C et al

in Grote, J; Stick, C (Eds.) Tissue response to hypoxia and ischemia (1996)

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See detailHormonal induction of an immediate-early gene response in myogenic cell lines--a paradigm for heart growth.
Maass, A.; Grohe, C.; Kubisch, C. et al

in European heart journal (1995), 16 Suppl C

Cardiac hypertrophy is characterized by growth of myocardial cells without proliferation. Many endo- paracrine stimuli such as angiotensin II, endothelin, alpha 1-adrenergic agonists, and insulin have ... [more ▼]

Cardiac hypertrophy is characterized by growth of myocardial cells without proliferation. Many endo- paracrine stimuli such as angiotensin II, endothelin, alpha 1-adrenergic agonists, and insulin have been shown to be able to induce cardiac hypertrophy either in vivo or in vitro. We have used the myoblast model of differentiation and proliferation to determine nuclear signal transduction mechanisms in muscle and (by analogy) cardiac growth. The first nuclear event known to occur when a growth stimulus acts upon a cell is induction of a family of immediate-early genes. Our group focused on the role of one of these genes, the early growth response gene-1 (Egr-1). We have shown that this gene is induced in isolated adult cardiac myocytes in the presence of endothelin. An anti-sense oligonucleotide complementary to the first six codons of the Egr-1 mRNA abolishes the stimulation of protein synthesis induced by endothelin. In the present study we further characterized paracrine growth stimuli in the myogenic cell line Sol8, which was used as a paradigm to further investigate mechanisms of paracrine growth induction. We demonstrated that a variety of candidate endo- paracrine stimuli for the induction of cardiac hypertrophy induced the Egr-1 messenger RNA in the myogenic cell line Sol8. Among these are endothelin, insulin, basic fibroblast growth factor, and platelet-derived growth factor BB (PDGF BB). We conclude: (1) In analogy to the myocardium, these growth factors act upon myoblasts. (2) This line appears to be a suitable model for the molecular characterization of Egr-1 target genes. [less ▲]

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See detailMitogenic signals control translation of the early growth response gene-1 in myogenic cells.
Maass, A.; Grohe, C.; Oberdorf, S. et al

in Biochemical and biophysical research communications (1994), 202(3), 1337-46

Muscle is a major site of expression of the early growth response gene-1 (Egr-1). To investigate its role in muscle proliferation and/or differentiation we studied the effect of a variety of growth ... [more ▼]

Muscle is a major site of expression of the early growth response gene-1 (Egr-1). To investigate its role in muscle proliferation and/or differentiation we studied the effect of a variety of growth factors on cultured mouse muscle Sol8 cells. Three groups of responses could be distinguished: 1. AII, endothelin, phenylephrine, and PMA induced Egr-1 mRNA accumulation, but the message remained untranslated. These factors induced neither differentiation nor proliferation. 2. Insulin induced differentiation. It stimulated Egr-1 mRNA accumulation, but no translation into the Egr-1 protein was seen. 3. bFGF, PDGF BB, and FCS strongly induced DNA- and protein synthesis (i.e. proliferation) and Egr-1 mRNA accumulation. Only under these conditions was the message translated into protein. We conclude: 1. AII, endothelin, phenylephrine, and PMA elicit a nuclear response in Sol8 muscle cells which may lead to reprogramming of genes unrelated to differentiation or proliferation. 2. Differentiation induces a translational block of the Egr-1 mRNA which is only relieved by mitotic stimuli. 3. These results strongly suggest a pivotal role of Egr-1 in muscle proliferation and define translational control as a new mechanism of Egr-1 regulation. [less ▲]

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See detailHyperosmotic stress induces immediate-early gene expression in ventricular adult cardiomyocytes.
Wollnik, B.; Kubisch, C.; Maass, A. et al

in Biochemical and biophysical research communications (1993), 194(2), 642-6

Mammalian cells possessing osmosensors have long been described in brain and kidney. The genetic basis of the response to hyperosmotic stress has been well characterized in prokaryotes. In contrast, the ... [more ▼]

Mammalian cells possessing osmosensors have long been described in brain and kidney. The genetic basis of the response to hyperosmotic stress has been well characterized in prokaryotes. In contrast, the genetic response of eukaryotic cells is poorly understood. Therefore we investigated the effect of hypertonic NaCl and sucrose solutions on the transcriptional activation of the immediate-early genes (IEGs) egr-1 and c-fos in isolated ventricular adult rat cardiomyocytes. We observed that even small increases in osmolarity to 315 +/- 5 mosmol/l and 370 +/- 8 mosmol/l by hypertonic NaCl solution resulted in dose-dependent induction of egr-1 (4-and 5-fold) and c-fos (3-and 4-fold), respectively. Hypertonic sucrose solution had the same effect on egr-1 and c-fos mRNA levels while increased sucrose concentration under isotonic conditions had no effect. Cardiomyocytes exposed to hypertonic media did not significantly shrink as shown by a cell length measurement. We conclude that isolated adult cardiomyocytes possess an osmoreceptor mechanism which is able to sense even slight changes in osmolarity and to translate these into a transcriptional response of the myocardial IEG program. [less ▲]

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See detailImmediate-early gene induction by repetitive mechanical but not electrical activity in adult rat cardiomyocytes.
Kubisch, C.; Wollnik, B.; Maass, A. et al

in FEBS letters (1993), 335(1), 37-40

Mechanical factors are thought to play an important role in the induction of myocardial hypertrophy. Yet, it is not known whether active contraction induces genes that probably represent initial steps in ... [more ▼]

Mechanical factors are thought to play an important role in the induction of myocardial hypertrophy. Yet, it is not known whether active contraction induces genes that probably represent initial steps in the hypertrophic response in the adult myocardium--and if so, whether the mechanical or the electrical component of the twitch governs this response. We therefore investigated whether electrical stimulation of contraction was able to induce the immediate-early genes (IEGs) egr-1 and c-fos in adult rat cardiomyocytes. Cyclical contraction led to an increase in egr-1 and c-fos mRNA levels within 30 min. Full inhibition of contraction during electrostimulation by the Ca(2+)-desensitizer 2,3-butanedione monoxime (BDM) totally blocked this IEG-response without altering membrane potential. These data suggest that in adult myocardium, the mechanical rather than the electrical activity is responsible for the IEG-response during active twitch. [less ▲]

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See detailDie Bedeutung des "early growth response gene-1" bei der Induktion der Hypertensiven Myokardhypertrophie
Neyses, Ludwig UL; Maass, A; Wollnik, B et al

in Regensburger Universitaetskolloquium: Fortschritte in der medizinischen Forschung - Hypertonie - molekulare Mechanismen/funktionelle Adaptation (1992)

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