The fibroblast growth factor and receptor multigene families

Enteric neuroimmune interactions coordinate intestinal responses in health and disease

The enteric nervous system (ENS) of the gastrointestinal (GI) tract interacts with the local immune system bidirectionally. Recent publications have demonstrated that such interactions can maintain normal GI functions during homeostasis and contribute to pathological symptoms during infection and inflammation. Infection can also induce long-term changes of the ENS resulting in the development of post-infectious GI disturbances. In this review, we discuss how the ENS can regulate and be regulated by immune responses and how such interactions control whole tissue physiology. We also address the requirements for the proper regeneration of the ENS and restoration of GI function following the resolution of infection.

Long-term follow-up and prognostic significance of angiogenic basic fibroblast growth factor (bFGF) expression in patients with breast cancer

The development of distant metastasis in breast cancer patients is the key step towards worse prognosis. The angiogenic basic fibroblast growth factor (bFGF) has been associated with tumorigenesis and metastasis in several human cancers. Therefore, bFGF expression was studied by immunohistochemistry in 111 patients with primary breast cancer. The results were correlated with prognostically relevant clinico-pathological features. such as tumor stage, grading. nodal stage and survival. bFGF was expressed in approximately 70% of the breast cancer tissues; 30% of the tumors showed strongly positive staining. With the exception of histological grading (p < 0.05), no correlation was found between the extent of bFGF expression and prognostic parameters. Analysis of survival showed a significantly (p < 0.05) prolonged survival for patients with a concomitant absence of axillary lymph node metastasis and bFGF immunoreactivity. Our data suggest that increased bFGF expression is a novel parameter for worse prognosis in nodal-negative breast cancer patients.

FIF [fibroblast growth factor-2 (FGF-2)-interacting-factor], a nuclear putatively antiapoptotic factor, interacts specifically with FGF-2

Numerous evidence indicates that some of the activities of fibroblast growth factor 2 (FGF-2) depend on an intracrine mode of action. Recently, we showed that three high molecular mass (HMM) nuclear forms of FGF-2 are part of a 320-kDa protein complex while the cytoplasmic AUG-initiated form is included in a 130-kDa complex. Consequently, the characterization of FGF endogenous targets has become crucial to allow the elucidation of their endogenous activities. Through the screening of GAL4-based yeast two-hybrid expression libraries, we have isolated a gene encoding a nuclear protein of 55 kDa, FIF (FGF-2-interacting-factor), which interacts specifically with FGF-2 but not with FGF-1, FGF-3, or FGF-6. In this system, FIF interacts equally well with the NH2-extended 24-kDa FGF form as with the 18-kDa form, indicating that the FIF-binding motif is located in the last 155 amino acids of FGF-2. Nevertheless, coimmunoprecipitation experiments showed an exclusive association with HMM FGF-2. The predicted protein contains a canonical leucine zipper domain and three overlapping hydrophobic heptad repeats. The region spanning these repeats is, together with a region located in the N-terminal part of the FIF protein, implicated in the binding to FGF-2. In contrast to the full-length FIF protein, several deletion constructs were able to transactivate a lac-Z reporter gene. Furthermore, the COOH-terminal part, but not the full-length FIF protein, has previously been shown to exhibit antiapoptotic properties. Thus we discuss the possibility that these activities could reflect a physiological function of FIF through its interaction with FGF-2.

Protective effect of neurotrophic factors, neuropoietic cytokines and dibutyryl cyclic AMP on hydrogen peroxide-induced cytotoxicity on PC12 cells: a possible link with the state of differentiation

We present evidence that the survival of PC12 cells exposed to hydroxyl radicals generated by hydrogen peroxide applied for 30 min at 1 mM was effective when they were differentiated in response to Nerve Growth Factor (NGF) and/or other inducers of neurite outgrowth such as basic-fibroblast growth factor and dibutyryl cyclic AMP. The time- and dose-dependent differentiation triggered by NGF was (1) markedly increased by basic fibroblast growth factor, interleukin-6 or dibutyryl cyclic AMP; (2) diminished by leukemia inhibitory factor or ciliary neurotrophic factor; (3) not potentiated by insulin-like growth factor I or progesterone. The influence of these various factors and agents on PC12 cells was evaluated by the estimation of neurite outgrowth, whereas their possible protective effects were assessed by the measurement of cell survival. Our results would indicate that the factors and agents that induced differentiation were also able to protect the cells against an oxidative stress.

Endogenous basic fibroblast growth factor isoforms involved in different intracellular protein complexes

Four forms of basic fibroblast growth factor (bFGF or FGF-2) result from an alternative initiation of translation involving one AUG (155-amino acid form) and three CUGs (210-, 201- and 196-amino acid forms). These different forms of bFGF show different intracellular biological activities. To identify their intracellular targets, the 210- and 155-amino acid forms of bFGF were independently transfected into CHO cells and their correct subcellular localizations were verified, the 155-amino acid bFGF form being essentially cytoplasmic whereas the 210-amino acid protein was nuclear. The radiation fragmentation method was used to determine the target size of the different bFGF isoforms in the transfected CHO cells and to show that the 210- and 155-amino acids bFGF isoforms were included in protein complexes of 320 and 130 kDa respectively. Similar results were obtained using the SK-Hep1 cell line, which naturally expressed all forms of bFGF. Co-immunoprecipitation assays using different chimaeric bFGF-chloramphenicol acetyltransferase proteins showed that different cellular proteins are associated with different parts of the bFGF molecule. We conclude that bFGF isoforms are involved in different molecular complexes in the cytosol and nucleus, which would reflect different functions for these proteins.

Differential expression of the fibroblast growth factor receptor (FGFR) multigene family in normal human adult tissues

This report describes a systematic analysis of the expression of the fibroblast growth factor receptor (FGFR) multigene family (FGFR1, FGFR2, FGFR3, and FGFR4) in archival serial sections of normal human adult tissues representing the major organ systems, using immunohistochemical techniques. Polyclonal antisera specific for FGFR1, FGFR2, FGFR3, and FGFR4 and a three-stage immunoperoxidase technique were employed to determine the cellular distribution of these receptors at the protein level. The expression profiles for the tissue-specific cellular localization of the FGFR multigene family demonstrated wide-spread and striking differential patterns of expression of individual receptors in the epithelia and mesenchyme of multiple tissues (stomach, salivary glands, pancreas, thymus, ureter, and cornea) and co-expression of FGFR1-4 in the same cell types of other tissues. The wide-spread expression of FGFR1-4 in multiple organ systems suggests an important functional role in normal tissue homeostasis. Differences in the spatial patterns of FGFR gene expression may generate functional diversity in response to FGF-1 and FGF-2, both of which bind with equally high affinity to more than one receptor subtype. In vivo, this may lead to functional differences that are crucial for the regulation of normal physiological processes and are responsible for the pathological mechanisms that orchestrate various disease processes.

Mutants of basic fibroblast growth factor identify different cellular response programs

Mutations, expected to affect the intracellular routing, i.e. additional nuclear localization sequences (NLS; the natural 23 kDa isoform and a 17D27R mutant) and/or a deletion of amino acids 26-29 (23 delta 26-29 and 17 delta 26-29), were introduced in basic fibroblast growth factor (bFGF). The mutants were assayed for their mitotic activity and their capacity to induce a tissue-specific response in human umbilical vein endothelial cells [HUVECs; induction of urokinase plasminogen activator receptor (u-PAR)], or in rat lens epithelial cells (fibre cell differentiation). In HUVECs, the 17D27R mutant had wild type activity, the 23 kDa and the delta 26-29 proteins were impaired in the induction of both mitosis and u-PAR. The delta 26-29 proteins, but not the 23 kDa protein or 17D27R mutant, were also impaired in receptor binding in that they bound only to a subset of receptors. The concentration of 17 kDa bFGF required for half maximal u-PAR response was 30 fold higher than for the half maximal 3H-thymidine incorporation. Addition of an NLS to bFGF strongly inhibited the induction of fibre cell differentiation, though it had little effect on the stimulation of DNA synthesis. The 17 delta 26-29 kDa mutant had wild type differentiation activity but was a poor mitogen for lens epithelial cells.

Vascular networks within the stroma of human long-term bone marrow cultures

The formation of branching and anastomosing vascular structures has been demonstrated within the stromal layers of human long-term bone marrow cultures (LTBMCs). Such organized vascular structures have not been described previously and may be of functional importance, as adherent granulocyte-predominant haemopoietic foci were more numerous in their interstices and margins than elsewhere in the stromal layers. Mature granulocytes were seen within vascular lumina in a few instances, possibly indicating an attempt to recapitulate the normal process of egress of neutrophils from bone marrow into the circulation. Immunostaining showed that the vascular structures expressed CD31, CD34, and CD105 (endoglin), which were not expressed by stromal fibroblastic cells. Collagen IV and laminin, expressed throughout the stroma, were present in increased amounts where vascular arrays were seen. In contrast, von Willebrand factor (VWF) and vascular cell adhesion molecule-1 (VCAM-1) were expressed equally by the vascular arrays and by stromal fibroblastic cells. Neither the arrays nor the general stroma expressed intercellular adhesion molecule-1 (ICAM-1), ICAM-2, ICAM-3, or endothelial leukocyte adhesion molecule-1 (ELAM-1).

Expression of the FGFR1 gene in human breast-carcinoma cells

Fibroblast growth factors (FGF) constitute a family of at least 9 members which act through high-affinity tyrosine-kinase receptors encoded by 4 distinct genes. In humans, the FGFR1 gene is located in chromosomal region 8p12. Its amplification and expression were examined in a panel of 110 breast carcinoma samples by Southern- and Northern-blot analyses. FGFR1 was amplified in 9% and overexpressed in about 15% of the tumors studied. In situ hybridization experiments were performed on tissue sections of normal breast and tumors with a high level of FGFR1 expression. In both normal and tumoral tissues, FGFR1 RNA was detected in the epithelial cells. Overexpression of FGFR1 seems to be associated with small, well-differentiated diploid tumors.

Purification and characterization of the 210-amino acid recombinant basic fibroblast growth factor form (FGF-2)

Four forms of basic fibroblast-growth factor (bFGF or FGF-2) using one AUG (155 amino acids) and three upstream CUG (210, 201 and 196 amino acids) start codons, were synthesized through an alternative use of initiation codons. The 210-amino acid form of FGF-2 (210FGF-2) was expressed in a plasmid vector under the control of a bacteriophage T7 RNA polymerase promoter system in Escherichia coli. Characterization of the purified protein was performed by electrospray mass spectrometry and Edman degradation. The recombinant 210FGF-2 produced in E. coli had a mitogenic activity similar to the 146-amino acid form extracted from tissues.