No abstract

Glycyl-L-histidyl-L-lysine (GHK) is a tripeptide with affinity for copper(H) ions and was isolated from human plasma.This peptide appears to play a physiological role in wound healing. We report the stimulating effect of GHK-Cu on collagen synthesis by fibroblasts. The stimulation began between IO-'2 and IO-" M, maximized at 10e9 M, and was independent of any change in cell number. The presence of a GHK triplet in the a;(I) chain of type I collagen suggests that the tripcptide might be liberated by proteases at the site of a wound and exert in situ healing effects.

The expression of fibroblast growth factor (FGF) 1, a potent neurotrophic factor, increases during differentiation and remains high in adult neuronal tissues. To examine the importance of this expression on the neuronal phenotype, we have used PC12 cells, a model to study FGF-induced neuronal differentiation. After demonstrating that FGF1 and FGF2 are synthesized by PC12 cells, we investigated if FGF1 expression could be a key element in differentiation. Using the cell signaling pathway to determine the effects of FGF1 alone, FGF1 plus heparin, or a mutated FGF1, we showed an activation to the same extent of mitogen-activated protein (MAP) kinase kinase and MAP kinase (extracellular regulated kinase 1). However, only FGF1 plus heparin could promote PC12 cell differentiation. Thus, the MAP kinase pathway is insufficient to promote differentiation. Analysis of the PC12 cells after the addition of FGF1 plus heparin or FGF2 demonstrated a significant increase in the level of FGF1 expression with the same time course as the appearance of the neuritic extensions. Transfection experiments were performed to enhance constitutivly or after dexamethasone induction the level of FGF1 expression. The degree of differentiation achieved by the cells correlated directly with the amount of FGF1 expressed. The MAP kinase pathway did not appear to be involved. Interestingly, a 5-fold increase in FGF1 in constitutive transfected cells extended dramatically their survival in serum-free medium, suggesting that the rise of FGF1 synthesis during neuronal differentiation is probably linked to their ability to survive in the adult. All of these data demonstrate that, in contrast to the MAP kinase cascade, FGF1 expression is sufficient to induce in PC12 cells both differentiation and survival. It also shows that auto-and trans-activation of FGF1 expression is involved in the differentiation process stimulated by exogenous FGFs through a new pathway which remains to be characterized. FGF11 and 2 are widely distributed in the peripheral and central nervous systems in the adult. In rat brain, FGF2 is present in most neurons within the cerebral cortex (1), hippocampus (2), and cerebellum (3). High levels of FGF1 expression have been observed in motor neurons, primary sensory neurons, and retinal ganglion neurons (4, 5). In chick brain, the expression of FGF1 is developmentally regulated (6). In bovine and rat embryonic retina, all neuronal layers express FGF1 with an appearance corresponding to their sequential differentiation (7, 8). In rat, the level of FGF1 expression remains uniformly low throughout the embryonic period until postnatal day 7. Thereafter, it increases rapidly, reaching a maximum in the adult retina. In the intermediate central nervous system, subclasses of FGF receptors appear to be down-regulated during development (9), and during retinal embryonic development, the expression of FGFR1 and FGFR2 follows the retinal layering (10). These patterns of FGF expression suggest that these growth factors are involved in the integrit...

Fibroblast growth factor 1 (FGF1) is a differentiation and survival factor for neuronal cells both in vitro and in vivo. FGF1 activities can be mediated not only by paracrine and autocrine pathways involving FGF receptors but also by an intracrine pathway, which is an underestimated mode of action. Indeed, FGF1 lacks a secretion signal peptide and contains a nuclear localization sequence (NLS), which is consistent with its usual intracellular and nuclear localization. To progress in the comprehension of the FGF1 intracrine pathway in neuronal cells, we examined the role of the nuclear translocation of FGF1 for its neurotrophic activity as well as for its protective activity against p53-dependent apoptosis. Thus, we have transfected PC12 cells with different FGF1 expression vectors encoding wild type or mutant (Delta NLS) FGF1. This deletion inhibited both FGF1 nuclear translocation and FGF1 neurotrophic activity (including differentiation and serum-free cell survival). We also show that endogenous FGF1 protection of PC12 cells against p53-dependent cell death requires FGF1 nuclear translocation. Strikingly, wild type FGF1 is found interacting with p53, in contrast to the mutant FGF1 deleted of its NLS, suggesting the presence of direct and/or indirect interactions between FGF1 and p53 pathways. Thus, we present evidences that FGF1 may act by a nuclear pathway to induce neuronal differentiation and to protect the cells from apoptosis whether cell death is induced by serum depletion or p53 activation.

The binding of iodinated basic fibroblast growth factor (bFGF) to low‐density heparan sulfate proteoglycan purified from the Engelbreth Holm Swarm (EHS) sarcoma was investigated using different techniques. The tumor clearly contained bFGF, the level being comparable to that found in other tissues such as human or bovine brain. 125I bFGF strongly bound to the basement membrane‐like matrix of EHS frozen sections as revealed by autoradiography. Iodinated bFGF bound to purified heparan sulfate proteoglycan but not to laminin or collagen type IV, three components isolated from the same tumor. In contrast, acidic fibroblast growth factor (aFGF) displayed negligible binding to heparan sulfate proteoglycan. Binding of bFGF to frozen sections and to purified proteoglycan could be strongly inhibited by heparin and was displaced by an excess of unlabeled factor and completely suppressed after heparitinase and heparinase treatments. Binding was a function of the salt concentration and was abolished at 0.6 M NaCl. Scatchard analysis indicated the affinity site had a Kd of about 30 nM, a value 10–15 higher than that recently reported by Moscatelli (J. Cell. Physiol., 131:123–130, 1987) in the case of the low‐affinity binding sites present on the surface of baby hamster kidney (BHK) cells.

NCI, the C-terminal non-collagenous globular domain of collagen IV, represents one of the two end regions responsible for the assembly and cross-linking of the extracellular network of basement membrane collagen. Several cDNA clones for the NCI domain of the ctl(IV) collagen chain of mouse have been isolated by using synthetic oligonucleotides as screening probes for mouse libraries. The oligonucleotides were synthesized according to known stretches of the corresponding protein sequence. Sequencing of the overlapping cDNA clones allowed the complete amino acid sequence of the NCl domain to be deduced as well as the C-terminal 165 amino acid residues of the triple helix. It consists of 229 amino acid residues which comprise two homologous regions with a high content of cysteine. These DNA and protein sequences are compared to the corresponding sequences of other collagens and discussed with respect to their structural and biological significance.The main collagenous component of basement membranes is collagen IV. The triple helical molecule is 400 nm long and carries a globular domain at its carboxy-terminal [l -31. It contains two ctl (IV) chains and one a2(IV) chain, each consisting of approximately 1700 amino acid residues [4, 51. The triple-helical part of these chains is frequently interrupted by non-helical regions [6, 71, in contrast to interstitial collagen chains. In basement membranes, collagen IV forms a macromolecular network in which the 30-rim-long N-terminal region (7s domain) of four molecules are linked together. Each of these molecules becomes connected at the opposite end, via the C-terminal globule (NCI domain), to the NCI domain of yet another molecule. The network is stabilized by the formation of intermolecular cross-links at both ends [8, 91. This organization differs from the assembly of the interstitial collagens I, I1 and 111, whose 300-nm-long molecules are aligned in parallel but in a D-staggered array (D = 67 nm)While the amino acid sequence of large parts of the triplehelical region of the al(1V) chain from human [7] and mouse [6] is known, the C-terminal globular domain proved to be difficult to characterize, probably because of its hydrophobic character. Since the NCI domain is important for the assembly of the molecules, we decided to determine its amino acid sequence via the corresponding cDNA. Appropriate for such investigations is poly(A)+ RNA from tissues and cell lines which are known to produce basement membranes and type IV collagen, in particular the EHS mouse tumor [l I], the PYS-2 cell line [I, 121 and 1101.both sources contain very little translatable mRNA for the chains of type IV collagen, the amount being estimated to be less than 0.1 % (M. Laurent, I. Oberbaumer, unpublished). However, induced F9 cells have been reported to contain higher levels of these mRNAs [I 51.Here we will present our data on three cDNA clones, two from an EHS library and one from an F9 library, which cover the C-terminal area of the triple helix, the globular domain of the a1 (IV) chai...

Our data again represent solid proof for the pivotal role of FGFR3 and TP53 mutations in superficial and invasive bladder tumors, respectively. However, other molecular markers should be identified for borderline pT1G3 bladder tumors, which are probably at the crossroads of these 2 distinct molecular pathways.

NOV is a selective proapoptotic factor for human adrenocortical cells. Reduced expression of NOV in ACTs may play an important role in the process of childhood ACT tumorigenesis, accounting at least in part for the defect of apoptotic regression of the fetal adrenal that has been proposed to be responsible for tumor formation.