Biomedical subjects

M C Dauchel

Publications and source records attributed to M C Dauchel.

6 recordsLinked to original sources

PubMed1992

High and low affinity membrane binding sites for fibroblast growth factors in the developing chick brain.

Acidic and basic fibroblast growth factors (aFGF and bFGF), two mitogenic, neurotrophic and angiogenic molecules, are present in the embryonic chick brain but their function remains unclear. In order to approach the biological activity of FGFs during brain development, we have looked for their receptors and studied their regulation through chick brain development. Competitive binding studies realized on brain membranes indicated the presence of two classes of FGF binding sites: high affinity binding sites (dissociation constant, Kd = 100 pM) and low affinity binding sites (Kd = 20 nM). Cross-competition experiments show that these two classes of binding sites both interact with aFGF and bFGF. The number of sites in these two classes of binding sites changes during embryogenesis. On the one hand, the membrane capacity of high affinity sites decreases from E7 (1 +/- 0.2 pmol/mg of protein) to E15 (0.5 +/- 0.2 pmol/mg of protein); on the other hand, the membrane capacity of low affinity sites increases from E15 (25 +/- 4 pmol/mg of protein) to P1 (75 +/- 20 pmol/mg of protein). Cross-linking experiments revealed the presence of two putative receptor forms of molecular masses of about 130 and 95 kDa. These results suggest that the biological activity of aFGF and bFGF during brain embryogenesis could be regulated by the expression of high and low affinity binding sites for these growth factors.

Animals↗

PubMed1991

Mitogenic properties of a new endothelial cell growth factor related to pleiotrophin.

A growth factor was isolated from a neutral pH extract of adult bovine brain. Purification of this polypeptide was achieved by a three step procedure including cationic exchange, heparin-Sepharose affinity and Mono S chromatography. This heparin binding protein had a molecular weight of 18,000 as assessed by silver-stained SDS-PAGE and was not immunologically and structurally related to acidic or basic FGF. Freshly purified protein had a maximal mitogenic effect on bovine brain capillary cells at a concentration of 100 pM. Microsequencing revealed an unique amino-terminal sequence homologous to heparin-binding growth-associated molecule (HB-GAM), a neuronal maturation protein, to pleiotrophin (PTN), a fibroblast cell growth factor and to one form of the putative protein product of the MK gene, a retinoic acid induced-gene.

Amino Acid Sequence↗

PubMed1989

Distribution of basic fibroblast growth factor binding sites in various tissue membrane preparations from adult guinea pig.

In order to localize a rich source of basic FGF receptor, we examined the distribution of basic FGF binding sites in brain, stomach, lung, spleen, kidney, liver and intestine membrane preparations from adult guinea pig. Comparative binding studies using iodinated basic FGF showed that a specific binding was detected in all the membrane preparations tested. Scatchard plots from iodinated basic FGF competition experiment with native basic FGF in various membrane preparations, suggested the presence of one class of binding sites in some tissues such as liver, kidney, spleen, lung, stomach, and intestine with an apparent dissociation constant (appKD) value ranging from 4 to 7.5 nM and the existence of a second class of higher affinity sites in brain membranes with appKD value of 15 pM. Characterization of these basic FGF high affinity interaction sites was performed using a cross-linking reagent. These results show for the first time that specific interaction sites for basic FGF are widely distributed, suggesting that this growth factor might play a role in the physiological functions of a number of adult organs.

Animals↗

PubMed1989

Modulation of mitogenic activity and cellular binding of basic fibroblast growth factor by basic proteins.

Polycationic molecules were studied either for their ability to displace the binding of basic fibroblast growth factor (bFGF) to high- and low-affinity membrane interaction sites and/or to modulate bFGF-induced proliferation of fibroblasts. Heparin-binding polypeptides, such as polylysine, protamine, histones, and thrombin-displaced [125I]bFGF bound to bovine brain membrane receptors. The most displacing polypeptides were those with the strongest affinity to heparin. Two of these polypeptides, protamine and polylysine, inhibited (at 5 microM) by more than 90% the mitogenic effect induced by bFGF on Chinese hamster lung fibroblast cells (CCL39). At the same dose, no effect was observed with basic proteins that do not bind to heparin, such as cytochrome C and lysozyme. An interesting observation was that protamine at 1 microM potentiated by 1.5-fold the mitogenic activity of bFGF, while it acted as an inhibitor at higher concentration.

Animals↗

PubMed1988

Presence of basic fibroblast growth factor receptors in bovine brain membranes.

We described a protocol for purification of bovine brain membranes suitable to study the binding of iodinated basic fibroblast growth factor (FGF) to bovine brain membrane preparation. The binding of 125I basic FGF to brain membranes reached equilibrium within 30 min at 20 degrees C, was reversible, and displaced by an excess of unlabeled basic FGF. Scatchard analysis of the data revealed that two classes of binding sites could be detected with an apparent Kd of 30 pM and a capacity of 0.24 pmol/mg of membrane proteins for the high affinity binding site and Kd of 3 nM with a capacity of 51 pmol/mg of membrane proteins for the low affinity binding site. Cross-linking experiments of labeled basic FGF to brain membrane receptor yield the formation of a single major complex with an apparent molecular mass of 170 kDa which is similar to the value obtained for the high affinity binding site for basic FGF on target cells in tissue culture. Hence these data present the first biochemical evidence suggesting that membrane purified from bovine brain contain two classes of specific binding sites for basic FGF and confirm results described with cells grown in vitro.

Animals↗

PubMed1987

Platelet derived growth factor is present in human placenta: purification from an industrially processed fraction.

Platelet derived growth factor was purified from an industrially processed fraction of human placenta (EAP) donated by the Institut Merieux. We first demonstrated that EAP contains PDGF and the quantity of this growth factor was estimated by inhibition of its biological activity using antibodies against PDGF. According to this first estimation, 1 l of EAP (obtained from 125 kg of placenta) contains 10-1000 micrograms of PDGF. A purification procedure including fast flow chromatography (cationic S), heparin Sepharose affinity, chromatography on Cibacron Blue followed by a reverse phase on a C8 column gave a 6000-fold enrichment with a yield of 14%. This result suggests that the PDGF content in 1 l of EAP is between 10 and 30 micrograms. Mitogenic activity was measured on human fibroblast AG1523, Chinese hamster fibroblasts CCL39 and bovine epithelial cells BEC. Dose-response curves indicate that our preparation of purified PDGF from human placenta induces 50% of the maximal tritiated thymidine incorporation in CCL39 at a dose of 5 ng of PDGF/ml of culture medium.

Biological Assay↗