ENTPDases of vertebrate retina

RICATTI MJ, ALFIE, LD., LAVOIE EG, SEVIGNY J, SCHWARZBAUM, PJ, FAILLACE, MP

SYNAPSE

WILEY-LISS, DIV JOHN WILEY & SONS INC

Lugar: New York; Año: 2009 vol. 63 p. 291 - 307

0887-4476

Ectonucleoside triphosphate diphosphohydrolases (E-NTPDases) are afamily of membrane-bound enzymes that hydrolyze extracellular di- and triphosphatenucleosides. E-NTPDases have been proposed to control extracellular nucleotide levelsthat mediate intercellular communication by binding to specific membrane receptors.Here we show a detailed immunocytochemical localization of two enzymes of the ENTPDasefamily in the retinal layers of two vertebrate species, namely, the mouse andthe zebrafish. In the mouse retina, NTPDase2 was chiefly localized in Mu¨ ller glia andganglion cell processes. NTPDase1 was located on neurons as well, since it wasexpressed by horizontal and ganglion cell processes, suggesting that nucleotides such asATP and ADP can be hydrolyzed at the surface of these cells. NTPDase1 was alsodetected in intraretinal blood vessels of the mouse. Regarding zebrafish, NTPDases1and 2 seem to be differentially localized in horizontal cell processes, photoreceptor segments,and ganglion cell dendrites and axons, but absent from Mu¨ ller glia. Moreover,NTPDases1 and 2 appear to be expressed within the germinal margin of the zebrafishretina that contains proliferative and differentiating cells. Retinal homogenates fromboth species exhibited ecto-ATPase activity which might be attributed at least toNTPDases1 and 2, whose expression is described in this report. Our results suggest acompartmentalized regulation of extracellular nucleotide/nucleoside concentration in theretinal layers, supporting a relevant role for extracellular nucleotide mediated-signalingin vertebrate retinas.