scholarly journals Overproduction of cardiac S-adenosylmethionine decarboxylase in transgenic mice

2005 ◽  
Vol 393 (1) ◽  
pp. 295-302 ◽  
Author(s):  
Oleg Nisenberg ◽  
Anthony E. Pegg ◽  
Patricia A. Welsh ◽  
Kerry Keefer ◽  
Lisa M. Shantz
Keyword(s):  
Transgenic Mice ◽  
Ornithine Decarboxylase ◽  
Fold Increase ◽  
Adrenergic Stimulation ◽  
Compensatory Mechanisms ◽  
Specific Expression ◽  
Adenosylmethionine Decarboxylase ◽  
Cardiac Phenotype ◽  
Founder Line ◽  
Do So

The present study was designed to provide a better understanding of the role played by AdoMetDC (S-adenosylmethionine decarboxylase), the key rate-controlling enzyme in the synthesis of spermidine and spermine, in controlling polyamine levels and the importance of polyamines in cardiac physiology. The αMHC (α-myosin heavy chain) promoter was used to generate transgenic mice with cardiac-specific expression of AdoMetDC. A founder line (αMHC/AdoMetDC) was established with a >100-fold increase in AdoMetDC activity in the heart. Transgene expression was maximal by 1 week of age and remained constant into adulthood. However, the changes in polyamine levels were most pronounced during the first week of age, with a 2-fold decrease in putrescine and spermidine and a 2-fold increase in spermine. At later times, spermine returned to near control levels, whereas putrescine and spermidine levels remained lower, suggesting that compensatory mechanisms exist to limit spermine accumulation. The αMHC/AdoMetDC mice did not display an overt cardiac phenotype, but there was an increased cardiac hypertrophy after β-adrenergic stimulation with isoprenaline (‘isoproterenol’), as well as a small increase in spermine content. Crosses of the αMHC/AdoMetDC with αMHC/ornithine decarboxylase mice that have a >1000-fold increase in cardiac ornithine decarboxylase were lethal in utero, presumably due to increase in spermine to toxic levels. These findings suggest that cardiac spermine levels are highly regulated to avoid polyamine-induced toxicity and that homoeostatic mechanisms can maintain non-toxic levels even when one enzyme of the biosynthetic pathway is greatly elevated but are unable to do so when two biosynthetic enzymes are increased.

Targeted overexpression of ornithine decarboxylase enhances β-adrenergic agonist-induced cardiac hypertrophy

2001 ◽  
Vol 358 (1) ◽  
pp. 25-32 ◽  
Author(s):  
Lisa M. SHANTZ ◽  
David J. FEITH ◽  
Anthony E. PEGG
Keyword(s):  
Transgenic Mice ◽  
Cardiac Hypertrophy ◽  
Ornithine Decarboxylase ◽  
Adrenergic Stimulation ◽  
Adrenergic Agonist ◽  
Specific Expression ◽  
Simultaneous Treatment ◽  
Constitutive Overexpression ◽  
Heart Induction

These studies were designed to determine the consequences of constitutive overexpression of ornithine decarboxylase (ODC) in the heart. Induction of ODC is known to occur in response to agents that induce cardiac hypertrophy. However, it is not known whether high ODC levels are sufficient for the development of a hypertrophic phenotype. Transgenic mice were generated with cardiac-specific expression of a stable ODC protein using the α-myosin heavy-chain promoter. Founder lines with > 1000-fold overexpression of ODC in the heart were established, resulting in a 50-fold overaccumulation of putrescine, 4-fold elevation in spermidine, a slight increase in spermine and accumulation of large amounts of cadaverine compared with littermate controls. Despite these significant alterations in polyamines, myocardial hypertrophy, as measured by ratio of heart to body weight, did not develop, although atrial natriuretic factor RNA was slightly elevated in transgenic ventricles. However, stimulation of β-adrenergic signalling by isoproterenol resulted in severe hypertrophy and even death in ODC-overexpressing mice without further altering polyamine levels, compared with only a mild hypertrophy in littermates. When β1-adrenergic stimulation was blocked by simultaneous treatment with isoproterenol and the β1 antagonist atenolol, a significant, although reduced, hypertrophy was still present in the hearts of transgenic mice, suggesting that both β1 and β2 adrenergic receptors contribute to the hypertrophic phenotype. Therefore these mice provide a model to study the in vivo co-operativity between high ODC activity and activation of other pathways leading to hypertrophy in the heart.

Abstract 311: Measurements of cAMP Dynamics in the SERCA2 Microdomain in Adult Mouse Cardiomyocytes using a Targeted FRET Biosensor

2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
Julia U Sprenger ◽  
Viacheslav O Nikolaev
Keyword(s):  
Transgenic Mice ◽  
Molecular Mechanisms ◽  
Ventricular Myocytes ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Heart Weight ◽  
Cell Fractionation ◽  
Adrenergic Stimulation ◽  
Cardiac Phenotype ◽  
Fractionation Analysis

PURPOSE: cAMP is a central regulator of cardiac function and disease. This global second messenger acts in a compartmentalized fashion, and changes in cAMP dynamics are linked to cardiac diseases. In this project, we visualized cAMP signals directly in such microdomains to gain insights into the molecular mechanisms involved in cAMP compartmentation and its alterations in hypertrophy. Methods: We generated transgenic mice expressing a new Förster resonance energy transfer (FRET)-based cAMP sensor Epac1-camps-PLN to measure cAMP dynamics in the microdomain around the sarco/endoplasmic reticulum Ca2+-ATPase 2 (SERCA2). This sensor is targeted to SERCA2 via phospholamban (PLN). Results: Colocalization and cell fractionation analysis confirmed proper localization of the sensor in transgenic mouse hearts. qPCR analysis revealed a two-fold overexpression of PLN. However, no adverse cardiac phenotype could be detected by histological analysis and heart weight to body weight ratios. Local cAMP dynamics were measured using freshly isolated adult ventricular myocytes and compared to cAMP signals in the bulk cytosol using cardiomyocytes from Epac1-camps mice. We detected the predominant role of phosphodiesterases (PDEs) 4 and 3 in the SERCA2 compartment under basal conditions. These PDEs were responsible for shaping the microdomain and its segregation from the cytosolic compartment. Interestingly, beta1-adrenergic stimulation led to a stronger increase of local cAMP in the SERCA2 compartment compared to the bulk cytosol. 8 weeks after transverse aortic constriction (TAC), PDE4 activity was downregulated in the SERCA2 microdomain compared to sham cardiomyocytes. Conclusion: We successfully generated transgenic mice expressing the targeted Epac1-camps-PLN biosensor to visualize cAMP dynamics in the SERCA2 compartment. We could show distinct cAMP dynamics around the SERCA2 compartment compared to the bulk cytosol and uncovered its alterations in hypertrophied cardiomyocytes

scholarly journals Transgenic mice expressing the human ornithine decarboxylase gene under the control of mouse metallothionein I promoter

1996 ◽  
Vol 314 (2) ◽  
pp. 405-408 ◽  
Author(s):  
Leena ALHONEN ◽  
Sami HEIKKINEN ◽  
Riitta SINERVIRTA ◽  
Maria HALMEKYTÖ ◽  
Pekka ALAKUIJALA ◽  
...  
Keyword(s):  
Transgenic Mice ◽  
Ornithine Decarboxylase ◽  
Mammalian Cells ◽  
Fold Increase ◽  
Transgenic Animals ◽  
Decarboxylase Activity ◽  
Transgenic Mouse Line ◽  
Regulatory Machinery ◽  
Dividing Cells ◽  
Very High

We have generated a transgenic mouse line harbouring the human ornithine decarboxylase gene under the control of mouse metallothionein I promoter. Even in the absence of an exposure to heavy metals, ornithine decarboxylase was over-expressed in heart, testis, brain, and especially in liver, of the transgenic animals. An exposure of the transgenic mice to zinc further enhanced the enzyme activity to a level which in liver represented up to 8000-fold increase in comparison with non-transgenic animals. The striking stimulation of liver ornithine decarboxylase activity upon treatment of the transgenic mice with zinc was accompanied by a nearly 150-fold increase in the hepatic putrescine content as compared with similarly treated non-transgenic animals. Even though the liver putrescine concentration reached that of spermidine and spermine in the transgenic animals, the contents of the higher polyamines only transiently increased upon zinc administration and then returned to the basal level. These findings once again indicate that mammalian cells possess extremely powerful regulatory machinery to prevent an over-accumulation of spermidine and spermine in non-dividing cells, and that very high tissue putrescine concentrations can be tolerated, at least for periods of a few days, with seemingly no phenotypic changes.

Ileal mucosal growth during intraluminal infusion of ethylamine or putrescine

1985 ◽  
Vol 249 (4) ◽  
pp. G434-G438 ◽  
Author(s):  
E. R. Seidel ◽  
M. K. Haddox ◽  
L. R. Johnson
Keyword(s):  
Protein Content ◽  
Ornithine Decarboxylase ◽  
Serum Gastrin ◽  
Decarboxylase Activity ◽  
Ileal Mucosa ◽  
Adenosylmethionine Decarboxylase ◽  
Serum Gastrin Concentration ◽  
Catheter Tip ◽  
Mucosal Growth ◽  
Do So

Either ethylamine or the diamine putrescine was infused at the rate of 1 mumol/h for 66 h into the ileal lumen of rats. Total mucosal RNA, DNA, and protein content was greater in amine-treated rats than in rats receiving 0.9% NaCl. Growth was greatest in the mucosa surrounding the tip of the infusion catheter but was also observed 9 cm proximal and distal to the catheter tip. Infusion of these amines induced the activity of the enzymes ornithine and S-adenosylmethionine decarboxylase. Ornithine decarboxylase activity was increased 2- and 6-fold and S-adenosylmethionine decarboxylase activity 10- and 5-fold by putrescine and ethylamine, respectively. Induction of the polyamine biosynthetic enzymes was not accompanied by increases in the tissue content of polyamines. Putrescine, spermidine, and spermine content of the ileal mucosa surrounding the catheter tip was the same in 0.9% NaCl-, ethylamine-, and putrescine-treated animals. Finally, ethylamine was without effect on serum gastrin concentration in these experiments. The results suggest that amines regulate mucosal growth and may do so by modulating the activity of the enzymes involved in the synthesis of the polyamines.

scholarly journals Modifications of major aspects of myocardial ribonucleic acid metabolism as a response to noradrenaline. Action of the hormone on cytoplasmic processing of ribonucleic acid after reserpine treatment

1977 ◽  
Vol 168 (3) ◽  
pp. 341-345 ◽  
Author(s):  
A Corti ◽  
A Casti ◽  
G Mezzetti ◽  
N Reali ◽  
G Orlandini ◽  
...  
Keyword(s):  
Ornithine Decarboxylase ◽  
Ribonucleic Acid ◽  
Fold Increase ◽  
Rabbit Heart ◽  
Polymerase Activity ◽  
Subcellular Fractions ◽  
Adenosylmethionine Decarboxylase ◽  
Reserpine Treatment ◽  
Perfused Hearts ◽  
Hydrolysis Of

Treatment of perfused rabbit heart with reserpine causes a decrease of incorporation of labelled precursors into RNA species of subcellular fractions and polyamines. Ornithine decarboxylase, S-adenosylmethionine decarboxylase and cytoplasmic Mn2+-stimulated polyadenylate polymerase activities are not modified. Addition of noradrenaline to reserpine-treated perfused hearts enhances, compared with the control, the incorporation of precursor into RNA in all subcellular fractions other than the nuclear one, restores incorporation of labelled putrescine into polyamines, enhances ornithine decarboxylase and S-adenosylmethionine decarboxylase activities and causes a 12-fold increase in cytoplasmic Mn2+-dependent polyadenylate polymerase activity. After treatment with noradrenaline the increase in radioactivity was found solely in AMP after hydrolysis of microsomal RNA to nucleoside monophosphates.

scholarly journals Characterization of transgenic mice with widespread overexpression of spermine synthase

2004 ◽  
Vol 381 (3) ◽  
pp. 701-707 ◽  
Author(s):  
Yoshihiko IKEGUCHI ◽  
Xiaojing WANG ◽  
Diane E. McCLOSKEY ◽  
Catherine S. COLEMAN ◽  
Paul NELSON ◽  
...  
Keyword(s):  
Transgenic Mice ◽  
Ornithine Decarboxylase ◽  
Strong Support ◽  
Normal Growth ◽  
Early Gene ◽  
Transgenic Expression ◽  
Adenosylmethionine Decarboxylase ◽  
Spermine Synthase ◽  
Gene Enhancer ◽  
Actin Promoter

A widespread increase in SpmS (spermine synthase) activity has been produced in transgenic mice using a construct in which the human SpmS cDNA was placed under the control of a composite CMV-IE (cytomegalovirus immediate early gene) enhancer–chicken β-actin promoter. Four separate founder CAG/SpmS mice were studied. Transgenic expression of SpmS was found in all of the tissues examined, but the relative SpmS activities varied widely according to the founder animal and the tissue studied. Very large increases in SpmS activity were seen in many tissues. SpdS (spermidine synthase) activity was not affected. Although there was a statistically significant decline in spermidine content and increase in spermine, the alterations were small compared with the increase in SpmS activity. These results provide strong support for the concept that the levels of the higher polyamines spermidine and spermine are not determined only by the relative activities of the two aminopropyltransferases. Other factors such as availability of the aminopropyl donor substrate decarboxylated S-adenosylmethionine and possibly degradation or excretion must also influence the spermidine/spermine ratio. No deleterious effects of SpmS overexpression were seen. The mice had normal growth, fertility and behaviour up to the age of 12 months. However, breeding the CAG/SpmS mice with MHC (α-myosin heavy chain)/AdoMetDC (S-adenosylmethionine decarboxylase) mice, which have a large increase in S-adenosylmethionine decarboxylase expression in heart, was lethal. In contrast, breeding the CAG/SpmS mice with MHC/ODC (L-ornithine decarboxylase) mice, which have a large increase in cardiac ornithine decarboxylase expression, had a protective effect in preventing the small decrease in viability of the MHC/ODC mice.

scholarly journals Transgenic mice overexpressing ornithine and S-adenosylmethionine decarboxylases maintain a physiological polyamine homoeostasis in their tissues

1997 ◽  
Vol 323 (2) ◽  
pp. 457-462 ◽  
Author(s):  
Ritva HELJASVAARA ◽  
Ildiko VERESS ◽  
Maria HALMEKYTÖ ◽  
Leena ALHONEN ◽  
Juhani JÄNNE ◽  
...  
Keyword(s):  
Transgenic Mice ◽  
Ornithine Decarboxylase ◽  
Metabolic Flux ◽  
Pulse Labelling ◽  
Spermidine Synthase ◽  
Tissue Concentrations ◽  
Adenosylmethionine Decarboxylase ◽  
Normal Limits ◽  
Primary Fibroblasts ◽  
Hybrid Mice

Recent work has shown that transgenic mice overexpressing human ornithine decarboxylase display no marked changes in the tissue concentrations of spermidine or spermine in spite of a dramatic increase in putrescine levels. In the tissues of transgenic mice carrying the human spermidine synthase gene and in those of hybrid mice overexpressing both ornithine decarboxylase and spermidine synthase, spermidine and spermine levels remain within normal limits. To test whether the amount of the propylamine group donor, decarboxylated S-adenosylmethionine, limits the conversion of putrescine into the higher polyamines, we have produced transgenic mouse lines harbouring the rat S-adenosylmethionine decarboxylase gene in their genome. However, neither these mice nor the hybrid mice overexpressing both ornithine decarboxylase and S-adenosylmethionine decarboxylase displayed significant changes in their spermidine and spermine tissue levels. To study the mechanism by which cells maintain the constancy of the polyamine concentrations, we have determined the metabolic flux of polyamines in transgenic primary fibroblasts using pulse labelling. The results indicate that the polyamine flow is faster in transgenic primary fibroblasts than in non-transgenic fibroblasts and that the intracellular homoeostasis of higher polyamines is maintained at least partly by the acetylation of spermidine and spermine and their secretion into the medium.

scholarly journals Transgenic mice over-producing putrescine in their tissues do not convert the diamine into higher polyamines

1993 ◽  
Vol 291 (2) ◽  
pp. 505-508 ◽  
Author(s):  
M Halmekytö ◽  
L Alhonen ◽  
L Alakuijala ◽  
J Jänne
Keyword(s):  
Transgenic Mice ◽  
Transgenic Mouse ◽  
Ornithine Decarboxylase ◽  
Specific Inhibitor ◽  
Mouse Line ◽  
Transgenic Mouse Line ◽  
Adenosylmethionine Decarboxylase ◽  
Adult Tissues ◽  
Ornithine Transaminase

We recently described a transgenic mouse line over-expressing the human ornithine decarboxylase gene virtually in all tissues. Despite strikingly elevated tissue putrescine concentrations, no or minimal changes were found in the levels of the higher polyamines spermidine and spermine. We have now extended these studies by further increasing tissue putrescine with the aid of 5-fluoromethylornithine, a specific inhibitor of ornithine transaminase and hence the catabolism of L-ornithine. As a result of the treatment with the latter drug, the concentration of putrescine was further increased by a factor of 2-3 without any changes in the concentrations of spermidine and spermine. In the testis of transgenic mice treated with 5-fluoromethylornithine, the concentration of putrescine was nearly 60 times that in non-transgenic untreated animals, yet the concentration of spermidine was only 1.5-fold higher. A similar small increase in brain spermidine was accompanied by a 40-fold elevation in the concentration of putrescine. The apparent blockade between putrescine and spermidine was in all likelihood not attributable to an inhibition of S-adenosylmethionine decarboxylase, the rate-controlling enzyme in the biosynthesis of spermidine and spermine. Our results are more compatible with the view that in non-dividing adult tissues putrescine is sequestered through some unknown mechanisms in a way that makes it unavailable for the synthesis of the higher polyamines.

scholarly journals Loss of β-adrenergic–stimulated phosphorylation of CaV1.2 channels on Ser1700 leads to heart failure

2016 ◽  
Vol 113 (49) ◽  
pp. E7976-E7985 ◽  
Author(s):  
Linghai Yang ◽  
Dao-Fu Dai ◽  
Can Yuan ◽  
Ruth E. Westenbroek ◽  
Haijie Yu ◽  
...  
Keyword(s):  
Heart Failure ◽  
Cardiac Hypertrophy ◽  
Troponin I ◽  
Contractile Function ◽  
Voluntary Exercise ◽  
Adrenergic Stimulation ◽  
Compensatory Mechanisms ◽  
Specific Expression ◽  
Altered Expression

L-type Ca2+ currents conducted by voltage-gated calcium channel 1.2 (CaV1.2) initiate excitation–contraction coupling in the heart, and altered expression of CaV1.2 causes heart failure in mice. Here we show unexpectedly that reducing β-adrenergic regulation of CaV1.2 channels by mutation of a single PKA site, Ser1700, in the proximal C-terminal domain causes reduced contractile function, cardiac hypertrophy, and heart failure without changes in expression, localization, or function of the CaV1.2 protein in the mutant mice (SA mice). These deficits were aggravated with aging. Dual mutation of Ser1700 and a nearby casein-kinase II site (Thr1704) caused accelerated hypertrophy, heart failure, and death in mice with these mutations (STAA mice). Cardiac hypertrophy was increased by voluntary exercise and by persistent β-adrenergic stimulation. PKA expression was increased, and PKA sites Ser2808 in ryanodine receptor type-2, Ser16 in phospholamban, and Ser23/24 in troponin-I were hyperphosphorylated in SA mice, whereas phosphorylation of substrates for calcium/calmodulin-dependent protein kinase II was unchanged. The Ca2+ pool in the sarcoplasmic reticulum was increased, the activity of calcineurin was elevated, and calcineurin inhibitors improved contractility and ameliorated cardiac hypertrophy. Cardio-specific expression of the SA mutation also caused reduced contractility and hypertrophy. These results suggest engagement of compensatory mechanisms, which initially may enhance the contractility of individual myocytes but eventually contribute to an increased sensitivity to cardiovascular stress and to heart failure in vivo. Our results demonstrate that normal regulation of CaV1.2 channels by phosphorylation of Ser1700 in cardiomyocytes is required for cardiovascular homeostasis and normal physiological regulation in vivo.

scholarly journals A 211-bp enhancer of the rat uncoupling protein-1 (UCP-1) gene controls specific and regulated expression in brown adipose tissue

1998 ◽  
Vol 333 (2) ◽  
pp. 243-246 ◽  
Author(s):  
Anne-Marie CASSARD-DOULCIER ◽  
Chantal GELLY ◽  
Frédéric BOUILLAUD ◽  
Daniel RICQUIER
Keyword(s):  
Adipose Tissue ◽  
Transgenic Mice ◽  
Brown Adipose Tissue ◽  
Reporter Gene ◽  
Uncoupling Protein ◽  
Transcriptional Response ◽  
Adrenergic Stimulation ◽  
Uncoupling Protein 1 ◽  
Specific Expression ◽  
Brown Adipose

The uncoupling protein-1 gene is uniquely expressed in brown adipose tissue (BAT) and is positively regulated by cold exposure of animals and the sympathetic nervous system. To analyse the importance of a previously identified 211-bp enhancer [Cassard-Doulcier, Gelly, Fox, Schrementi, Raimbault, Klaus, Forest, Bouillaud and Ricquier (1993) Mol. Endocrinol. 7, 497–506] in the tissue-specific expression of this gene, transgenic mice were generated using the chloramphenicol acetyltransferase (CAT) gene as a reporter gene. One out of fourteen lines of the control transgenic mice bearing the Herpes simplex thymidine kinase (TK) promoter expressed weakly the CAT reporter gene in several tissues, whereas the other lines did not express CAT. Eight founders bearing the 211-bp enhancer-TK transgene were obtained. In six lines, no expression of CAT was detected. In one line, the expression of CAT was restricted to BAT. In another line, the expression of CAT was found in BAT and, to a lesser extent, in testis. Moreover, in these lines a marked and specific increase in the expression of the reporter gene in BAT was observed either after exposure of mice to the cold or by treating them with a β-adrenoceptor agonist drug. These results demonstrate that the 211-bp enhancer alone is sufficient to both direct and restrict expression to BAT. This enhancer also mediates the transcriptional response of the gene to β-adrenergic stimulation, although it does not contain conserved cAMP response element.

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