Extracellular ADP via P2Y1 receptors regulates lesion-induced cell proliferation and death in the adult zebrafish retina

ARIADNA BATTISTA , M. PAULA FAILLACE

Fort Lauderdale, Florida

Congreso; ARVO 2012 -Translational Research: Seeing the possibilities; 2012

The Association for Research in Vision and Ophtalmology (ARVO)

Extracellular ADP via P2Y1 receptors regulates lesion-induced cell proliferation and death in the adult zebrafish retina Authors: Ariadna Gabriela Battista1 and Maria Paula Faillace1,2 Affiliations: 1. Department of Physiology, School of Medicine, University of Buenos Aires 2. Institute of Biological Chemistry and Physicochemistry (IQUIFIB)-CONICET Purpose: Regeneration and growth that occurs in the adult teleost retina have been helpful in identifying molecular and cellular mechanisms underlying cell proliferation and differentiation. Retina cannot regenerate if photoreceptor cells remain undamaged. However, it has also been described that damage to the inner retinal cells can trigger retinal repair without disturbing photoreceptor cells. The aim of this study was to investigate the role of extracellular nucleotides on retinal regeneration. Methods: Zebrafish were lesioned by intravitreal injections of different concentrations of ouabain. Then, apyrase (enzyme that hydrolyses nucleotides) or different antagonists of purinergic receptors were injected daily for 6 days in the ouabain-treated eyes. On day 7, cell proliferation or death were determined. Cell proliferation was assessed by BrdU incorporation for either 6-day or 24-hour periods. Results: We observed that treatment with MRS2179, an antagonist of the ADP-activated P2Y1 receptor, completely blocked lesion-induced increase in cell division. In contrast, cell proliferation was not affected by blocking ADP-activated P2Y12 and P2Y13 receptors. Likewise, the injection of an antagonist of adenosine P1 receptors or a mixture of antagonists for ATP-activated P2Y11 or P2X1, P2X2, P2X3 receptors did not modify lesion-induced cell division. Additionally, extracellular nucleotides hydrolysis by treatment with apyrase significantly increased cell death in injured retinas. This effect was partially reproduced by blocking P2Y1 receptors. We also observed, by qRT-PCR, that lesioned-retinas showed a significant increase of P2Y1 receptor mRNA expression relative to non-damaged retinas in the proliferative phase, whereas P2Y12 and P2X7 receptor mRNA levels did not change. Conclusions: Nucleotides, particularly ADP action via P2Y1 receptors, are necessary to control cell-cycle activity to enhance progenitor cell proliferation during retinal repair, regardless the magnitude of the injury or if this includes photoreceptor cell death.