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| Author(s): |
Ana Carolina Deckmann
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Faculdade de Ciências Médicas |
| Defense date: | 2008-02-27 |
| Examining board members: |
Kleber Gomes Franchini;
Gonçalo Amarante Guimarães Pereira;
Fernando Ferreira Costa;
Edecio Cunha Neto;
Mari Cleide Sogayar
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| Advisor: | Kleber Gomes Franchini |
| Abstract | |
The term acute coronary syndrome includes unstable angina and myocardial infarction, which are frequent and potentially lethal clinical entities. Both situations are characterized by an imbalance between myocardial oxygen supply and demand, often triggered by the reduced perfusion caused by narrowing or occlusion of coronary arteries due to atherosclerosis. The high morbidity and mortality rates determined by these conditions are attributed mainly to loss of myocardial and electrical instabilities, arising not only from ischemia, but also from spontaneous or induced reperfusion of the ischemic regions. Thus, there is much interest in the development of strategies and pharmacological agents able to minimize the injuries caused not only by myocardial ischemia but also by reperfusion. Experimental and clinical data indicate that systemically administered adenosine (Ado) is able to protect the myocardium from ischemia/reperfusion injuries. The protection induced by Ado occurs in two phases, an acute (1-6 hours) and a late (1-3 days) phase after a single dose administration. While acute protection depends on activation of signaling pathways that mobilize end-effectors constitutively expressed in the cells, the late protection depends on the alterations of the expression of genes involved in multiple cellular functions. However, some characteristics of the systemic action of Ado, such as its short half-life and cardiovascular side effects (i.e. bradycardia and hypotension), are major barriers to its clinical use in acute coronary syndromes. One way to circumvent these undesirable effects is to use pharmacological agents that increase Ado bioavailability, as antagonists of its transporters or adenosine kinase (ADK) inhibitors. ADK is a key enzyme in the metabolism of purines that phosphorilates adenosine to AMP by ATP hydrolysis. In this context, we have previously demonstrated that derivatives of anilinoquinazolines are potent inhibitors of adenosine kinase and induce both acute and late phases of cardioprotection, as showed in isolated heart model. The present study was designed to investigate the transcriptional responses involved in late cardioprotection induced by administration of the anilinoquinazoline DMA. We used oligonucleotide microarrays containing representative sequences of all genes from mouse genome (~35 thousand genes). The RNA probes were synthesized from hearts of mice treated with DMA (30 mg/kg, single dose) ou vehicle (DMSO), 24 and 48 hours prior to tissue excision. We considered differentially expressed (fold change>[2.0], p<0.1) a total of 1061 genes in 24-hour and 844 genes in 48-hour groups, in comparison to vehicle treated samples. Most of these transcripts were unknown genes (ESTs-Expressed Sequence Tags; 63% at 24 hours, 76% in 48 hours). In 24h transcriptome, most of the genes (75% of the known genes and 62% of ESTs) were upregulated, while in 48h transcriptome 56% of the known genes and 58% of ESTs were upregulated. The functional analysis of known genes showed large representation of classes associated with cell adhesion, signaling, transport and metabolism in 24 hours, and cell adhesion, development of multicellular organism and metabolism in 48 hours. The analysis of gene identities revealed few coincidences between the two transcriptomes, and clustering analysis performed to study the gene profile transition from 24 to 48h revealed that most genes presents transitory regulation of its expression (i.e., tendency of upregulation at 24h followed by downregulation at 48h and vice-versa). Analysis of differentially expressed genes in terms of metabolic and signaling pathways in which they are inserted allowed us to assess a putative metabolome of myocardial cells treated by the quinazoline DMA. Results indicated that the most affected pathways are glucose and lipids metabolism, PPAR-? and adipocytokines, angiogenic responses, among others. Among these results, we confirmed experimentally the angiogenic effect of DMA and also the expression of genes and proteins associated with modifications in cardiac energy metabolism. Our results indicate that various cellular responses, including the energetic metabolism, ion homeostasis and changes in cell osmolarity, must cooperate to induce the cardioprotection phenotype after DMA administration. Studies focusing the mechanistic modifications of these groups of genes will contribute to elucidate their involvement in the protection induced by treatment with quinazolines, and will provide clues to comprehend myocardial protection phenomenon. Keywords: cardioprotection, quinazolinic compounds, gene expression, oligonucleotide microarrays, Mus musculus (AU) | |