Injury-induced purinergic signalling molecules upregulate pluripotency gene expression and mitotic activity of progenitor cells in the zebrafish retina

MEDRANO MP; BEJARANO CA; BATTISTA AG; VENERA GD; BERNABEU RO; FAILLACE MP

PURINERGIC SIGNALLING

SPRINGER

Año: 2017

1573-9538

ABSTRACTDamage in fish activates retina repair that restores sight. The purinergic signalling system serves multiplehomeostatic functions and has been implicated in cell cycle control of progenitor cells in the developingretina. We examined whether changes in the expression of purinergic molecules were instrumental in theproliferative phase after injury of adult zebrafish retinas with ouabain. P2RY1 mRNA increased early afterinjury and showed maximal levels at the time of peak progenitor cell proliferation. Extracellularnucleotides, mainly ADP, regulate P2RY1 transcriptional and protein expression. The injury-inducedupregulation of P2RY1 is mediated by an autoregulated mechanism. After injury, the transcriptionalexpression of ecto-nucleotidases and ecto-ATPases also increased and ecto-ATPase activity inhibitorsdecreased Müller glia-derived progenitor cell amplification. Inhibition of P2RY1 endogenous activationprevented progenitor cell proliferation at two intervals after injury: one in which progenitor Müller gliamitotically activates and a second one in which Müller glia-derived progenitor cells amplify. ADPSinduced the expression of lin28a and ascl1a genes in mature regions of uninjured retinas. The expressionof these genes, which regulate multipotent Müller glia reprogramming, was significantly inhibited byblocking the endogenous activation of P2RY1 early after injury. We consistently observed that the numberof GFAP-BrdU-positive Müller cells after injury was larger in the absence than in the presence of theP2RY1 antagonist. Ecto-ATPase activity inhibitors or P2RY1 specific antagonists did not modify apoptoticcell death at the time of peak progenitor cell proliferation. The results suggested that ouabain injuryupregulates specific purinergic signals which stimulates multipotent progenitor cell response.