Hspa9 is required for pronephros specification and formation in Xenopus laevis.
BACKGROUND
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 studied the role of Hspa9 (heat shock 70 kDa protein 9) encoding a mitochondrial chaperone in pronephros development.


RESULTS
We first showed that Hspa9 is highly expressed in the pronephros territory and elongating nephric duct. We then observed that upon reduced retinoic acid signaling hspa9 expression was reduced as pax8 and pax2. Overexpression of hspa9 enlarged the pax8 positive pronephros territory, leading to a larger pronephric tubule. Loss of function of hspa9 in the kidney field using morpholino approach severely reduced pax8 expression and pronephros formation. Phenotypic rescue was achieved by co-injection of the full-length murine Hspa9 mRNA. However, no rescue was observed when Hspa9 mRNA lacking the mitochondrial-targeting sequence was injected, as this truncated form is able to interfere with pronephros formation when injected solely.


CONCLUSIONS
Hspa9 is an important mediator for pronephros development through modulation of pax8. Mitochondrial functions of hspa9 are likely to be involved in specification of pronephric cell fate.
Université Toulouse 3 Centre de Biologie du Développement, Toulouse, France.
Lionel
L
Gassié
Université Rennes 1, Rennes, France.
Aude
A
Lombard
Université Lyon 1 Institut Universitaire Technologique, Villeurbanne, France.
Tiphanie
T
Moraldi
Université Toulouse 3 Centre de Biologie du Développement, Toulouse, France.|CNRS UMR 5547, Toulouse, France.
Anne
A
Bibonne
Université Toulouse 3 Centre de Biologie du Développement, Toulouse, France.|CNRS UMR 5547, Toulouse, France.
Catherine
C
Leclerc
Université Toulouse 3 Centre de Biologie du Développement, Toulouse, France.|CNRS UMR 5547, Toulouse, France.
Marc
M
Moreau
Yale' School of Medicine Department of Internal Medicine, New Haven, Connecticut, USA.
Arnaud
A
Marlier
Université Toulouse 3 Centre de Biologie du Développement, Toulouse, France.|CNRS UMR 5547, Toulouse, France.|Institut National de la Santé et de la Recherche Médicale, Toulouse, France.
Thierry
http://orcid.org/0000-0002-5897-3740
T
Gilbert
D000818:Animals; D018507:Gene Expression Regulation, Developmental; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D051761:Paired Box Transcription Factors / Q000235:genetics / Q000378:metabolism; D060910:Pronephros / Q000196:embryology* / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D014212:Tretinoin / Q000378:metabolism; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis
D018840:HSP70 Heat-Shock Proteins; D024101:Mitochondrial Proteins; D051761:Paired Box Transcription Factors; D029867:Xenopus Proteins; D014212:Tretinoin
calcium; kidney development; mitochondria; mortalin; vitamin A