Fibroblast growth factor 2 (FGF-2) is an important modulator of cell growth and differentiation and a neurotrophic factor. FGF-2 occurs in isoforms, at a low molecular weight of 18,000 and at least two high molecular weight forms (21,000 and 23,000), representing alternative translation products from a single mRNA. In addition to its role as an extracellular ligand, FGF-2 localizes to the nuclei of cells. Here we show differential localization of the 18-and 23-kDa isoforms in the nuclei of rat Schwann cells. Whereas the 18-kDa isoform was found in the nucleoli, nucleoplasm, and Cajal bodies, the 23-kDa isoform localized in a punctuate pattern and associates with mitotic chromosomes suggesting different functional roles of the isoforms. Moreover, we show here that the 23-kDa FGF-2 isoform co-immunoprecipitates specifically with the survival of motor neuron protein (SMN). SMN is an assembly and recycling factor of the splicing machinery and locates to the cytoplasm, the nucleoplasm, and nuclear gems, where it co-localizes with 23-kDa FGF-2. Patients with spinal muscular atrophy suffer from fatal degeneration of motoneurons because of mutations and deletions of the gene for the SMN protein.A number of mitogenic growth factors, growth-regulatory proteins, and growth factor receptors have been reported to be localized in the cell nucleus and its substructures: e.g. plateletderived growth factor, fibroblast growth factor-1 (FGF-1), 1 FGF-2, and ciliary neurotrophic factor (1, 2). The data show that nuclear localization is a general phenomenon for some growth factors, suggesting nuclear functions independent of the function as extracellular factors.FGF-2 is a member of the FGF family, which has been shown to mediate a variety of biological processes during development and in the adult organism, including mitogenesis, angiogenesis, chemotaxis, mesoderm induction, and differentiation of various mesoderm-and neuroectoderm-derived cells. FGF-2 as an extracellular ligand is able to bind to high affinity tyrosine transmembrane receptors (FGF receptors, FGFR). FGF-2 has been shown to bind to all four known FGFR, however, with distinct affinities (3).FGF-2 exists in protein isoforms translated from a common messenger RNA by alternative use of AUG (18,000 isoform) and CUG (high molecular weight isoforms 21,000 and 23,000) start codons. The isoforms exert different biological effects when overexpressed in different cell types. Specific effects seen by the 23-kDa isoform but not the 18-kDa isoform after overexpression are reduced spreading of pancreatic cancer cells (4), the ability of NIH 3T3 cells to grow in low serum medium (5), increased radioresistance in HeLa cells (6), growing in serumfree medium of rat AR4 -2J cells (7), and differential effects on binucleation and nuclear morphology of neonatal rat cardiac myocytes (8). We have previously shown that in PC12 cells and rat immortalized Schwann cells, cell growth and morphology are altered after transfection with constructs coding for 18-and 23-kDa FGF-2, respectively (9, 1...

Basic fibroblast growth factor (FGF-2) has been shown to enhance the survival and neurite extension of various types of neurons including spinal ganglion neurons. In addition, endogenous FGF-2 and FGF receptors are upregulated following peripheral nerve lesion in ganglia and at the lesion site. FGF-2 protein is expressed in different isoforms (18 kDa, 21 kDa, 23 kDa) and differentially regulated after nerve injury. In the rat we analyzed the regenerative capacity of the high molecular weight (HMW) FGF-2 isoforms (21/23 kDa) to support the regeneration of the axotomized adult sciatic nerve across long gaps. The nerve stumps were inserted into the opposite ends of a silicone chamber resulting in an interstump gap of 15 mm. Silicone tubes were filled with Matrigel or a mixture of Schwann cells (SC) and Matrigel. SC were prepared from newborn rats and transfected to overexpress HMW FGF-2. Four weeks after the operation procedure, channels were analyzed with regard to tissue cables bridging both nerve stumps and myelinated axons distal to the original proximal nerve stump. Peripheral nerves interposed with HMW Schwann cells displayed significantly enhanced nerve regeneration, with the greatest number of tissue cables containing myelinated axons and the highest number of myelinated axons. These results suggest that a cellular substrate together with a source of a trophic factor could be a promising tool to promote nerve regeneration and, therefore, become useful also for a clinical approach to repair long gaps.

Pancreatic cancer is characterized by an increasing incidence and an extremely poor prognosis. It is resistant to most of the conventional treatment modalities. Histomorphologically, it presents with a strong desmoplastic reaction around cancer cells, and lymphocytes are typically localized as aggregates in the fibrotic interstitial tissue. Using the method of multi-epitope imaging with fluorochrome-tagged specific MoAbs which allows the simultaneous localization and characterization of T cells in tissues, we studied phenotypes and distribution of tumour-infiltrating lymphocytes (TIL) in pancreatic cancer. CD3+ T cells comprised up to 90% of the tumour-infiltrating cells which were either CD4+ or CD8+, most of them being memory cells (CD45RO+). In decreasing order of frequency, T lymphocytes carried the markers for CD45RO, CD18, CD103 and TCR gammadelta. Very few natural killer cells (CD56+) were observed. Twenty percent of CD8+ were labelled with CD103. These CD8+CD103+ T cells, analogous to the gut intraepithelial lymphocytes (IEL), were found in the fibrous interstitial tissue. Furthermore, an inverse correlation was found between the expression of CD18, the beta2-integrin, which mediates adhesion of activated lymphocytes, and CD45RO in the CD8+ subset of TIL (P = 0.046). In conclusion, phenotyping of T lymphocytes in pancreatic cancer raises the possibility that pancreatic cancer cells develop several strategies to escape the T cell-induced cytolysis by (i) the aggregation of cytotoxic CD8+CD103+ T cells in the fibrous tissue distant from the tumour cells, and (ii) the presence of CD18-bearing cells which lack the expression of the activation marker CD45RO.

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