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Talasila, A

Talasila, Amarnath

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Characterisation of P2Y receptors expressed in neonatal rat cardiac fibroblasts and their role in a model of ischaemic heart disease

Cardiac fibroblasts (CFs) are the predominant cell type in the cardiac tissue and play a vital role in wound healing, hypertrophy and fibrosis. During heart failure there is accumulation of ATP and UTP in the heart, possibly leading to stimulation of P2Y receptors in fibroblasts. However, very little is known about the functional expression and role of P2Y receptors in CFs. Therefore, the aim of this study was to characterise the different subtypes of P2Y receptors expressed in neonatal rat CFs and to investigate their role in an in vitro model of ischaemic heart disease. 

  

P2Yi, P2Y2, P2Y4, P2Y6, P2Y13 were detected by RT-PCR and immunocytochemistry. P2Y11-like receptor was identified at the protein level. Adenine (ADP-βS, ATP, ATP-γS, 2MeSADP and 2MeSATP) and uracil (UDP and UTP) nucleotides stimulated inositol phosphate (IP) response in an YM-254890 (Gq/11-protein inhibitor)-sensitive manner. AMP, ADP-βS, ATP and ATP-γS increased cAMP accumulation, whereas UDP and UTP inhibited forskolin-induced cAMP accumulation, which was abolished by pertussis toxin (Gq/11-protein inhibitor). The selective P2Yi antagonist MRS2179 inhibited ADP-?S, ATP-?S and 2MeSADP-induced IP accumulation. The UDP and UTP-mediated IP responses were blocked by MRS2578, a selective P2Y1 antagonist. These data provide strong evidence of the co-expression of P2Y1, P2Y2, P2Y4, P2Y6 and P2Y11-like receptors coupled to Gq/11-protein. In addition, P2Y2 and P2Y4 subtypes are also coupled to Gi/o whereas P2Yn-like to Gs-proteins. CFs may also express a P2Y-like receptor activated by AMP.

  

The effect of ATP-γS and UTP on cytokine release (IL-1β, IL-6, TNF-α and TGF-β1), cell viability, collagen synthesis and protein kinase activation (MAPK and Akt/PKB) was determined in CFs exposed to hypoxia and angiotensin-II as a model of ischaemic heart disease. IL-1β production was regulated by both ATP-γS and UTP whereas IL-6 release was induced by ATP-γS. ATP-γS and UTP did not effect the TNF-α and TGF-β1 production. ATP-γS mediated the deposition of collagen whereas UTP inhibited the collagen accumulation. Both the nucleotides did not affect CF viability or activate MAPK and Akt/PKB. 

  

In conclusion, neonatal rat CFs functionally express P2Yi, P2Y2, P2Y4, P2Yg and P2Yn-like receptors. The data also suggest that P2Y receptors activated by ATP-γS induce cardiac fibrosis and hypertrophy whereas P2Y receptors stimulated by UTP inhibit fibrosis, during ischaemic heart disease. In addition, this study showed the importance of P2Y receptors on CFs in the context of heart disease however, their role in myocardial remodelling requires further studies

Characterisation of P2Y receptors expressed in neonatal rat cardiac fibroblasts and their role in a model of ischaemic heart disease

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