Extracellular nucleotide receptors and ecto-ATPase activity are involved in the induction and amplification of neuronal progenitor cell number for retinal regeneration in zebrafish.

MEDRANO, MATÍAS PEDRO; BEJARANO, CLAUDIO ALEJANDRO; FAILLACE, MARÍA PAULA

Valparaíso

Simposio; ICGEB-Chile Third International Course and Meeting of the Latin American Zebrafish Network (LAZEN)?; 2014

LAZEN

ABSTRACT Here we described that the activity of ectonucleoside tri-phosphate diphosphohydrolases (NTPDases), which hydrolyze extracellular nucleotides, regulate daughter progenitor cell proliferation following Müller glia activation for regeneration of the adult zebrafish retina. In addition, ADP-activated P2Y1 receptors (P2Y1R) were key regulators of cell cycle at the interval in which Müller cell activate and daughter progenitor cell population amplify for retinal repair. We detected apoptotic cells on days 3-7 post injury. However, either antagonism of the P2Y1R or inhibition of ecto-ATPase, including NTPDase, activity did not affect the number of apoptotic cells. Furthermore, we first described several P2 receptors expressed by the adult zebrafish retina at the transcriptional level. Regenerating retinas showed a significant increase of P2Y1R mRNA expression at the time of peak proliferation. Additionally, P2Y1R mRNA levels in the intact retina were enhanced by in vivo exposure to ADPbS, whereas ATPgS was ineffective. This suggested that P2Y1R expression following injury could result from endogenous ADP extracellular signaling. In the zebrafish retina and brain, P2Y1R protein was detected by western blot as a 63 kDa monomer like the form exhibited by rat and human brains. After injury, P2Y1R, assessed by immunocytochemistry, showed enhanced levels and a modified distribution in the retinal layers. Moreover, treatment following damage with an antagonist of P2Y1R provoked a drastic decrease in this receptor protein levels. Some BrdU-positive retinal cells might express P2Y1R suggesting a direct effect of extracellular nucleotides on their mitotic activity. Furthermore, NTPDase1, 2 and 3 mRNA exhibited augmented levels following injury. Grant sponsors: ANCYPT FONCYT BID 1729/04 PICT 2004 No2542. CONICET PIP 2009-2011 N|01N 0169. UBACYT 2011-2014 N 0823. Univesity of Buenos Aires, ARGENTINA.