The aging myocardium expresses many gene transcripts that are normally expressed during embryonic and fetal development. Using transcriptome-based and promoter-based techniques, we have worked towards understanding the mechanisms underlying this control of gene expression both in models of development and in aging. Serial analysis of gene expression (SAGE) yields a quantitative, representative and comprehensive differential gene expression profile. We have employed SAGE analysis to generate a quantitative transcript assessment that has proven to be much more rapid and economical than other techniques. We used an RT-PCR based technique to determine the time points where a number of mesodermal and cardiac-restricted gene products are expressed in differentiated EC derived cardiomyocytes, and more recently feeder layers general employed to maintain embryonic stem cells. These latter studies were designed to identify factors that could possibly reprogram cells to become more multipotent.? We have utilized quantitative PCR and in situ hybridizations to analyze the temporal and spatial distribution of a number of the most differentially regulated transcripts identified by SAGE, several of which have shown a cardiac predominance in either fetal or adult heart. The novel gene products identified in this study provide a framework for the analysis of pre- and early cardiac developmental processes in human and mouse embryonic stem cells and are the subject of active investigation. Included among these gene transcripts that have been subjected to follow-up analysis are Cripto and pleiotrophin.? Since the original identification, we have determined that pleiotrophin (PTN), a development-regulated cytokine growth factor that promotes angiogenesis, cell proliferation and differentiation, is prominently expressed in developing myocardium but it is poorly expressed in adult heart. Conversely, in a rat model of myocardial infarction and in human dilated cardiomyopathy, pleiotrophin is markedly up-regulated, suggesting that it may have a functional role in injury repair. To elucidate the effects of PTN on contractile cells, we employed primary cultures of rat neonatal (NN) and adult (A) cardiomyocytes (CM). We found that PTN promotes caspase-mediated genomic DNA fragmentation in a dose- and time-dependent manner. More importantly, it significantly potentiates the apoptotic response of NNCMs to hypoxic stress and to ultraviolet (UV) irradiation, and of ACMs to hypoxia-reoxygenation. We furthermore found that PTN potentiated UV-induced apoptosis is abolished in NNCMs following siRNA-mediated knockdown of endogenous PTN proteins. Mechanistically, PTN antagonizes IGF-1 associated Ser-473 phosphorylation of AKT/PKB, and it concomitantly decreases both BAD and GSK3beta; phosphorylation. Adenoviral expression of constitutively active AKT and lithium chloride mediated inhibition of GSK3beta; also reduced the programmed cell death potentiated by PTN. These latter data indicate that PTN promotes CM cell death, at least partially, through inhibition of AKT signaling. In conclusion, we have uncovered a novel role for PTN in CMs. This cytokine, which in addition to its pro-angiogenic effects in heart, potentiates CM programmed cell death in response to pro-apoptotic stress.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Intramural Research (Z01)
Project #
1Z01AG000283-10
Application #
7732184
Study Section
Project Start
Project End
Budget Start
Budget End
Support Year
10
Fiscal Year
2008
Total Cost
$284,568
Indirect Cost
Name
National Institute on Aging
Department
Type
DUNS #
City
State
Country
United States
Zip Code
Nikolova, Teodora; Wu, Minyao; Brumbarov, Krassimir et al. (2007) WNT-conditioned media differentially affect the proliferation and differentiation of cord blood-derived CD133+ cells in vitro. Differentiation 75:100-11
Li, Jinliang; Wei, Hong; Chesley, Alan et al. (2007) The pro-angiogenic cytokine pleiotrophin potentiates cardiomyocyte apoptosis through inhibition of endogenous AKT/PKB activity. J Biol Chem 282:34984-93
Wiese, Cornelia; Rolletschek, Alexandra; Kania, Gabriela et al. (2006) Signals from embryonic fibroblasts induce adult intestinal epithelial cells to form nestin-positive cells with proliferation and multilineage differentiation capacity in vitro. Stem Cells 24:2085-97
Boheler, Kenneth R; Tarasov, Kirill V (2006) SAGE analysis to identify embryonic stem cell-predominant transcripts. Methods Mol Biol 329:195-221
Volkova, Maria; Garg, Rahul; Dick, Salihah et al. (2005) Aging-associated changes in cardiac gene expression. Cardiovasc Res 66:194-204
Boheler, Kenneth R; Crider, David G; Tarasova, Yelena et al. (2005) Cardiomyocytes derived from embryonic stem cells. Methods Mol Med 108:417-35
Anisimov, S V; Boheler, K R (2003) Aging-associated changes in cardiac gene expression: large scale transcriptome analysis. Adv Gerontol 11:67-75
Brady, Marc; Koban, Maren U; Dellow, Kimberley A et al. (2003) Sp1 and Sp3 transcription factors are required for trans-activation of the human SERCA2 promoter in cardiomyocytes. Cardiovasc Res 60:347-54
Fijnvandraat, Arnoud C; van Ginneken, Antoni C G; Schumacher, Cees A et al. (2003) Cardiomyocytes purified from differentiated embryonic stem cells exhibit characteristics of early chamber myocardium. J Mol Cell Cardiol 35:1461-72
Anisimov, Sergey V; Tarasov, Kirill V; Riordon, Daniel et al. (2002) SAGE identification of differentiation responsive genes in P19 embryonic cells induced to form cardiomyocytes in vitro. Mech Dev 117:25-74

Showing the most recent 10 out of 11 publications