Fetal mouse kidney maturation in vitro: Coordinated influences of epidermal growth factor, transferrin and hydrocortisone

Abstract

We have investigated the individual and combined actions of epidermal growth factor (EGF), transferrin and hydrocortisone on the maturation of whole fetal mouse metanephroi maintained in serum-free conditions for up to 5 days. The presence of EGF (100 ng/ml) resulted in elevated levels of [3H]-thymidine incorporation when compared to controls; autoradiograms showed that the proliferation of mesenchymal cells in the nephrogenic zone is particularly enhanced as verified by cell counting. Brush border hydrolase activities (alkaline phosphatase and gamma-glutamyltransferase), on the other hand, were significantly diminished. Transferrin (5 micrograms/ml) slightly stimulated DNA synthesis and potentiated EGF mitogenic action. The activation of DNA replication by the growth factor seems to be mediated through the protein kinase C pathway. When added alone, hydrocortisone (10(-6) M) strongly inhibited DNA synthesis, stimulated hydrolase activities and exerted a positive effect on brush border differentiation. When combined with EGF or to EGF + transferrin, hydrocortisone counteracted the effects of these latter peptides on DNA synthesis and enzyme activities. Considering the earlier observation of a reciprocal relation between proliferation and differentiation during the neotubulogenic phase of kidney development, the results described in the current study suggest that synergistic and synarchic actions of these heterologous factors are involved in the regulation of tubulogenesis.

Mitogenic effects of EGF/TGFα and immunolocalization of cognate receptors in human fetal kidneys

“…1(A)) but lower amounts (1-5 ng/ml) of both factors exerted no significant effect on this parameter. It is interesting to note that similar results were obtained in the presence of EGF and TGFα when using fetal mouse kidneys [11,12]. Furthermore, we observed that the addition of an anti-EGF receptor antibody (monoclonal from Calbiochem) to the culture medium neutralized the effect of exogenous EGF and even decreased basal 3 H-thymidine incorporation (Fig.…”

“…Nephronic epithelium represented another target of their stimulatory action on DNA synthesis, although it exhibited a weaker responsiveness. Knowing that EGF exerts similar activities on fetal mouse kidneys in organ culture [12] or after EGF injection in infant mice [7], we would like to propose that the fetal form of EGF plays an ubiquitous role by contributing to the regulation of metanephrogenesis in mammalian species. This idea is opposed to our recent finding that another growth factor, namely insulin, might act differentially in human and mouse as a promoter of renal cell proliferation (to be published).…”

“…It solely stimulated cell survival by reversing apoptosis in uninduced renal blastemas and it upregulated the proliferation of peritubular cells (expansion of interstitium) in the same organs cultured with inducers or in post-induced blastemas [21,44]. Using kidneys from mouse and human fetuses maintained in serum-free organ culture [5,12], we have previously shown that EGF stimulates DNA synthesis and alters some brush border hydrolase activities after 2 and 5 days. Furthermore, our studies indicated that EGF and transferrin exert additive effects on DNA synthesis and that phosphatidic acid, a natural agonist of the protein kinase C pathway, can mimick the action of exogenous mitogens.…”

Modulation of Cell Differentiation in Perfusion Culture

“…The functional differentiation of nephron epithelia on the one hand depends on humoral factors such as vitamin A derivates [9]and growth factors or hormones [10, 11, 12, 13], and on the other hand on structural elements such as the extracellular matrix [4]. In addition to these very heterogeneous developmental stimuli it was shown for MDCK cells that also changes in the pH and osmolarity are able to evoke differentiation [14, 15, 16, 17].…”

TGF-Alpha mRNA Expression in Renal Organogenesis: A Study in Rat and Human Embryos

“…By showing the actual presence of the TGFα gene transcript and TGFα peptide throughout rat kidney organogenesis as well as in the very early crucial phases of human metanephros development, the present data demonstrate that specific cells of renal primordia actively synthesize TGFα suggesting that this growth factor influences not only the in vitro induced tubulogenesis [7, 17, 18]but also controls in vivo nephrogenic processes throughout the distinct steps of renal organogenesis in cooperation with other growth factors and extracellular matrix molecules [19]. …”