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Hspa9 is required for pronephros specification and formation in Xenopus laevis

par Eric AGIUS - publié le

Gassié L, Lombard A, Moraldi T, Bibonne A, Leclerc C, Moreau M, Marlier A and Gilbert T

Development of the pronephros in Xenopus laevis is largely dependent on retinoic acid signaling at the time of kidney field specification with the simultaneous occurrence of a necessary calcium signaling. At the crossroads of these two signaling pathways, we analyzed the role of Hspa9 (heat shock 70kDa protein 9) encoding a mitochondrial chaperone in pronephros development. Hspa9 is highly expressed in the pronephros territory and modulated by retinoic acid signaling. Overexpression of hspa9 enlarged the pax8 positive pronephros territory, leading to a larger pronephric tubule whereas loss of function severely reduced pronephric pax8 expression and subsequently pronephros formation. Although full rescue was achieved by co-injection of the full length murine Hspa9 mRNA, no rescue was observed upon injection of a truncated form of Hspa9 mRNA lacking the mitochondrial-targeting sequence. We then showed that was this truncated form is able to interfere with pronephros formation when injected solely, illustrating that mitochondrial functions of hspa9 are likely to be involved in specification of pronephric cell fate.

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