Midkine is involved in kidney development and in its regulation by retinoids.
In the kidney, in which development depends on epithelial-mesenchymal interactions, it has been shown that retinoids modulate nephrogenesis in a dose-dependent manner in vivo and in vitro. Midkine (MK) is a retinoic acid responsive gene for a heparin-binding growth factor. The aim of the present study was therefore to quantify the expression of MK mRNA during renal development in the rat, to analyze the regulation of MK expression by retinoids in vivo and in vitro, and, finally, to study the role of MK in rat metanephric organ cultures. The spatiotemporal expression of MK in fetal kidney was studied. In control rats, MK expression is ubiquitous at gestational day 14, i.e., at the onset of nephrogenesis. On day 16, MK is expressed in the condensed mesenchyme and in early epithelialized mesenchymal derivatives. On gestational day 21, MK is rather localized in the nonmature glomeruli of the renal cortex. In utero exposure to vitamin A deficiency did not modify the specific spatial and temporal expression pattern of MK gene in the metanephros, although a decrease in mRNA expression occurred. In metanephroi explanted from 14-d-old fetuses and cultured in a defined medium, expression of MK mRNA was found to be stimulated when retinoic acid (100 nM) was added in the culture medium. Finally, in vitro nephrogenesis was strongly inhibited in the presence of neutralizing antibodies for MK: the number of nephrons formed in vitro was reduced by approximately 50% without changes in ureteric bud branching morphogenesis. These results indicated that MK is implicated in the regulation of kidney development by retinoids. These results also suggested that MK plays an important role in the molecular cascade of the epithelial conversion of the metanephric blastema.
Vilar
José
J
*Unité de Recherches, INSERM U356, IFR 58, Université Paris 6; Unité de Recherches, INSERM U430, IFR 58, Hôpital Broussais; and Unité de Recherches, INSERM U440, Institut du Fer à Moulin, Paris, France.
Lalou
Claude
C
*Unité de Recherches, INSERM U356, IFR 58, Université Paris 6; Unité de Recherches, INSERM U430, IFR 58, Hôpital Broussais; and Unité de Recherches, INSERM U440, Institut du Fer à Moulin, Paris, France.
Van Huyen
Jean-Paul Duong
JD
*Unité de Recherches, INSERM U356, IFR 58, Université Paris 6; Unité de Recherches, INSERM U430, IFR 58, Hôpital Broussais; and Unité de Recherches, INSERM U440, Institut du Fer à Moulin, Paris, France.
Charrin
Stéphanie
S
*Unité de Recherches, INSERM U356, IFR 58, Université Paris 6; Unité de Recherches, INSERM U430, IFR 58, Hôpital Broussais; and Unité de Recherches, INSERM U440, Institut du Fer à Moulin, Paris, France.
Hardouin
Sylvie
S
*Unité de Recherches, INSERM U356, IFR 58, Université Paris 6; Unité de Recherches, INSERM U430, IFR 58, Hôpital Broussais; and Unité de Recherches, INSERM U440, Institut du Fer à Moulin, Paris, France.
Raulais
Daniel
D
*Unité de Recherches, INSERM U356, IFR 58, Université Paris 6; Unité de Recherches, INSERM U430, IFR 58, Hôpital Broussais; and Unité de Recherches, INSERM U440, Institut du Fer à Moulin, Paris, France.
Merlet-Bénichou
Claudie
C
*Unité de Recherches, INSERM U356, IFR 58, Université Paris 6; Unité de Recherches, INSERM U430, IFR 58, Hôpital Broussais; and Unité de Recherches, INSERM U440, Institut du Fer à Moulin, Paris, France.
Leliévre-Pégorier
Martine
M
*Unité de Recherches, INSERM U356, IFR 58, Université Paris 6; Unité de Recherches, INSERM U430, IFR 58, Hôpital Broussais; and Unité de Recherches, INSERM U440, Institut du Fer à Moulin, Paris, France.
D000818:Animals; D000906:Antibodies / Q000276:immunology; D002352:Carrier Proteins / Q000276:immunology / Q000502:physiology*; D016207:Cytokines; D005314:Embryonic and Fetal Development / Q000502:physiology; D005260:Female; D005333:Fetus / Q000187:drug effects / Q000378:metabolism; D007668:Kidney / Q000196:embryology* / Q000254:growth & development*; D000078792:Midkine; D009924:Organ Culture Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D012176:Retinoids / Q000502:physiology*; D014801:Vitamin A / Q000494:pharmacology
D000906:Antibodies; D002352:Carrier Proteins; D016207:Cytokines; D012176:Retinoids; D014801:Vitamin A; D000078792:Midkine