Contribution of E-NTPDase1 (CD39) to renal protection from ischemia-reperfusion injury

Previous studies showed increased extracellular nucleotides during renal ischemia- reperfusion. While nucleotides represent the main source for extracellular adenosine and adenosine signaling contributes to renal protection from ischemia, we hypothesized a role for ecto- nucleoside- triphosphate- diphosphohydrolases ( E- NTPDases) in renal protection. We used a model of murine ischemia- reperfusion and in situ ischemic preconditioning ( IP) via a hanging weight system for atraumatic renal artery occlusion. Initial studies with a nonspecific inhibitor of E- NTPDases ( POM- 1) revealed inhibition of renal protection by IP. We next pursued transcriptional responses of E- NTPDases ( ENTPDase1 - 3, and 8) to renal IP, and found a robust and selective induction of E- NTPDase1/ CD39 transcript and protein. Moreover, based on clearance studies, plasma electrolytes, and renal tubular histology, IP protection was abolished in gene- targeted mice for cd39 whereas increased renal adenosine content with IP was attenuated. Furthermore, administration of apyrase reconstituted renal protection by IP in cd39 -/ - mice. Finally, apyrase treatment of wild- type mice resulted in increased renal adenosine concentrations and a similar degree of renal protection from ischemia as IP treatment. Taken together, these data identify CD39- dependent nucleotide phosphohydrolysis in renal protection. Moreover, the present studies suggest apyrase treatment as a novel pharmacological approach to renal diseases precipitated by limited oxygen availability.