A pro-survival effect of polyamine depletion on norepinephrine-mediated apoptosis in cardiac cells: role of signaling enzymes
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Recent studies report that the primary transmitter of sympathetic nervous system norepinephrine (NE), which is actively produced in failing human heart, is able to induce apoptosis of rat cardiomyocytes. Apoptotic cell death of cardiomyocytes is involved in several cardiovascular diseases including ischemia, hypertrophy and heart failure, therefore representing a potential therapeutic target. The natural occurring polyamines, putrescine, spermidine and spermine, are biogenic amines involved in many cellular processes, including apoptosis. Thus, we have studied the involvement of polyamines in the apoptosis of cardiac cells induced by the treatment with NE. The results indicate that NE caused an early induction of the activity of ornithine decarboxylase (ODC), the first enzyme in polyamine biosynthesis, followed by a later increase of apoptotic cell death. This effect was prevented in the presence of α-difluoromethylornithine, an irreversible inhibitor of ODC. Moreover, the study of some key signal transduction pathways revealed an involvement of AMP-activated protein kinase, AKT and p38 mitogen-activated protein kinases, in the modulation by polyamines of the response of cardiomyocytes to NE. In fact, polyamine-depleted cells showed an altered activation pattern of these kinases that may contrast apoptosis and appeared to result from a differential effect on the specific phosphatases that dephosphorylate and switch off these signaling proteins. In conclusion, these results indicate that in cardiac cells polyamines are involved in the execution of the death program activated by NE, and suggest that their apoptosis facilitating action is mediated by a network of specific phosphatases and kinases.
KeywordsNorepinephrine Cardiac cells Apoptosis Polyamines Kinases Phosphatases
The excellent technical assistance of Maddalena Zini is acknowledged. This work was supported by grants from University of Bologna (R.F.O.), Istituto Nazionale per le Ricerche Cardiovascolari (INRC) and Compagnia di San Paolo, Torino, Italy.
- Abbate A, Scarpa S, Santini D, Palleiro J, Vasaturo F, Miller J, Morales C, Vetrovec GW, Baldi A (2006) Myocardial expression of survivin, an apoptosis inhibitor, in aging and heart failure: an experimental study in the spontaneously hypertensive rat. Int J Cardiol 11(3):371–376CrossRefGoogle Scholar
- Capano M, Crompton M (2006) Bax translocates to mitochondria of heart cells during simulated ischaemia: involvement of AMP-activated and p38 mitogen-activated protein kinases. Biochem J 1:57–64Google Scholar
- Davies SP, Helps NR, Cohen PT, Hardie DG (1995) 5-AMP inhibits dephosphorylation, as well as promoting phosphorylation, of the AMP-activated protein kinase. Studies using bacterially expressed human protein phosphatase-2C alpha and native bovine protein phosphatase-2AC. FEBS Lett 377:421–425PubMedCrossRefGoogle Scholar
- Flamigni F, Pignatti C, Muscari C, Giordano E, Tantini B, Stefanelli C (2009) Experimental studies on the involvement of polyamines in cardiac remodeling. In: Toninello A et al (eds) Biologically active amines and related enzymes: biochemical physiological and clinical aspects. Transworld Research Network, Kerala, pp 71–83Google Scholar
- Mao W, Iwai C, Keng PC, Vulapalli R, Liang CS (2006) Norepinephrine-induced oxidative stress causes PC-12 cell apoptosis by both endoplasmic reticulum stress and mitochondrial intrinsic pathway: inhibition of phosphatidylinositol 3-kinase survival pathway. Am J Physiol Cell Physiol 290(5):C1373–C1384PubMedCrossRefGoogle Scholar