The enpp4 ectonucleotidase regulates kidney patterning signalling networks in Xenopus embryos

Karine Massé,Christian Paroissin,Eric Boué-Grabot,Lilly Maneta-Peyret,Surinder Bhamra,Elizabeth A Jones

doi:10.1038/s42003-021-02688-9

Abstract

The enpp ectonucleotidases regulate lipidic and purinergic signalling pathways by controlling the extracellular concentrations of purines and bioactive lipids. Although both pathways are key regulators of kidney physiology and linked to human renal pathologies, their roles during nephrogenesis remain poorly understood. We previously showed that the pronephros was a major site of enpp expression and now demonstrate an unsuspected role for the conserved vertebrate enpp4 protein during kidney formation in Xenopus. Enpp4 over-expression results in ectopic renal tissues and, on rare occasion, complete mini-duplication of the entire kidney. Enpp4 is required and sufficient for pronephric markers expression and regulates the expression of RA, Notch and Wnt pathway members. Enpp4 is a membrane protein that binds, without hydrolyzing, phosphatidylserine and its effects are mediated by the receptor s1pr5, although not via the generation of S1P. Finally, we propose a novel and non-catalytic mechanism by which lipidic signalling regulates nephrogenesis.

Highlights

The enpp ectonucleotidases regulate lipidic and purinergic signalling pathways by controlling the extracellular concentrations of purines and bioactive lipids
The enpp proteins, which belong to the ectonucleotidase subfamily, are key regulators of both purinergic and lipidic signalling pathways with their dual enzymatic activities of hydrolysing purines and generating S1P and lysophosphatidic acid (LPA) bioactive lipids[15]
We have demonstrated that the pronephros is the major site of expression for the amphibian enpp genes family, in particular, enpp[4] is highly expressed in Xenopus laevis pronephric tubules[16]

Summary

Introduction

The enpp ectonucleotidases regulate lipidic and purinergic signalling pathways by controlling the extracellular concentrations of purines and bioactive lipids. We have demonstrated that the pronephros is the major site of expression for the amphibian enpp genes family, in particular, enpp[4] is highly expressed in Xenopus laevis pronephric tubules[16] These data provided the first temporal and spatial embryonic expression profile for this evolutionally conserved enzyme which remains functionally poorly understood[17,18,19]. While its knock-down leads to kidney formation defects, the overexpression of wild-type Enpp[4], but not an inactive enzymatic protein, induces the formation of ectopic pronephroi characterized mostly by the presence of proximal tubule markers but in rare occasion of more distal tubule markers These effects are mediated by the lipidic receptor S1pr[5] and we show that Enpp[4] binds to phosphatidylserine, implying a role for bioactive lipids in pronephrogenesis. We provide evidence that enpp[4] misexpression alters the expression of members of the Notch, Wnt and RA signalling pathways and we propose a model for the mechanisms of action for Enpp[4] and lipidic signalling in kidney development

Methods

Results

Conclusion