In bovine adrenal medullary cells synergistically acting type 1 and type 2 angiotensin II (AII) receptors activate the fibroblast growth factor-2 (FGF-2) gene through a unique AII-responsive promoter element. Both the type 1 and type 2 AII receptors and the downstream cyclic adenosine 1',3'-monophosphate- and protein kinase C-dependent signaling pathways activate the FGF-2 promoter through a novel signal-transducing mechanism. This mechanism, which we have named integrative nuclear FGF receptor-1 signaling, involves the nuclear translocation of FGF receptor-1 and its subsequent transactivation of the AII-responsive element in the FGF-2 promoter.

The integrative nuclear FGFR1 signaling (INFS) pathway functions in association with cellular growth, differentiation, and regulation of gene expression, and is activated by diverse extracellular signals. Here we show that stimulation of angiotensin II (AII) receptors, depolarization, or activation protein kinase C (PKC) or adenylate cyclase all lead to nuclear accumulation of fibroblast growth factor 2 (FGF-2) and FGFR1, association of FGFR1 with splicing factor-rich domains, and activation of the tyrosine hydroxylase (TH) gene promoter in bovine adrenal medullary cells (BAMC). The up-regulation of endogenous TH protein or a transfected TH promoter-luciferase construct by AII, veratridine, or PMA (but not by forskolin) is abolished by transfection with a dominant negative FGFR1TK-mutant which localizes to the nucleus and plasma membrane, but not by extracellularly acting FGFR1 antagonists suramin and inositolhexakisphosphate (IP6). Mechanism of TH gene activation by FGF-2 and FGFR1 was further investigated in BAMC and human TE671 cultures. TH promoter was activated by co-transfected HMW FGF-2 (which is exclusively nuclear) but not by cytoplasmic FGF-1 or extracellular FGFs. Promoter transactivation by HMWFGF-2 was accompanied by an up-regulation of FGFR1 specifically in the cell nucleus and was prevented FGFR1(TK-) but not by IP6 or suramin. The TH promoter was also transactivated by co-transfected wild-type FGFR1, which localizes to both to the nucleus and the plasma membrane, and by an exclusively nuclear, soluble FGFR1(SP-/ NLS) mutant with an inserted nuclear localization signal. Activation of the TH promoter by nuclear FGFR1 and FGF-2 was mediated through the cAMP-responsive element (CRE) and was associated with induction of CREB-and CBP/P-300-containing CRE complexes. We propose a new model for gene regulation in which nuclear FGFR1 acts as a mediator of CRE transactivation by AII, cell depolarization, and PKC.

Some time ago, an accurate phenomenological approach, the BSW model, was developed for protonproton and antiproton-proton elastic scattering cross sections at center-of-mass energies above 10 GeV. This model has been used to give successful theoretical predictions for these processes, at successive collider energies. The BSW model involves a combination of integrals that, while computable numerically at fairly high energies, require some mathematical analysis to reveal the high-energy asymptotic behavior. In this paper we present a high-energy asymptotic representation of the scattering amplitude at moderate momentum transfer, for the leading order in an expansion parameter closely related to the logarithm of the center-of-mass energy. The fact that the expansion parameter goes as the logarithm of the energy means that the asymptotic behavior is accurate only for energies greatly beyond any foreseeable experiment. However, we compare the asymptotic representation against the numerically calculated model for energies in a less extreme region of energy. The asymptotic representation is given by a simple formula which, in particular, exhibits the oscillations of the differential cross section with momentum transfer. We also compare the BSW asymptotic behavior with the Singh-Roy unitarity upper bound for the diffraction peak.

Two known zebrafish dystrophin mutants, sapje and sapje-like (sap c/100 ), represent excellent small-animal models of human muscular dystrophy. Using these dystrophin-null zebrafish, we have screened the Prestwick chemical library for small molecules that modulate the muscle phenotype in these fish. With a quick and easy birefringence assay, we have identified seven small molecules that influence muscle pathology in dystrophin-null zebrafish without restoration of dystrophin expression. Three of seven candidate chemicals restored normal birefringence and increased survival of dystrophin-null fish. One chemical, aminophylline, which is known to be a nonselective phosphodiesterase (PDE) inhibitor, had the greatest ability to restore normal muscle structure and up-regulate the cAMP-dependent PKA pathway in treated dystrophin-deficient fish. Moreover, other PDE inhibitors also reduced the percentage of affected sapje fish. The identification of compounds, especially PDE inhibitors, that moderate the muscle phenotype in these dystrophin-null zebrafish validates the screening protocol described here and may lead to candidate molecules to be used as therapeutic interventions in human muscular dystrophy.phosphodiesterase inhibitor | chemical treatment M uscular dystrophy is a disease in which the muscle forms normally at first but then degenerates faster than it can be repaired. The most common form of muscular dystrophy is Duchenne muscular dystrophy (DMD), representing more than 90% of the diagnosed cases. Mutations in the dystrophin gene were found to be the cause of both DMD and Becker muscular dystrophy (1, 2). Currently, prednisone is the only treatment option available for muscular dystrophy patients in the United States, although there are currently other options through approved clinical trials. Other treatments currently being tested or considered for treating muscular dystrophy include the small molecule PTC124, which promotes read-through of nonsense mutations (3), encouraging muscle development by myostatin down-regulation (4, 5), and the use of oligonucleotides to promote exon skipping to restore dystrophin expression (6).Recently, a number of chemical and drug screens have been published using zebrafish embryos (7-11). It is possible to quickly produce large numbers of mutant offspring that can then be assayed in multiwell plates and treated with different chemicals to determine if disease progression is modulated. Many of these screens have been highly successful in disease modeling (7) and drug screening (8-10), making the zebrafish ideal for highthroughput whole-organism screening of candidate compounds. Chemical compounds of relatively small molecular weight can bind to specific proteins and alter their function, resulting in nonheritable phenotype changes.In addition to their suitability for chemical screens, zebrafish also represent a good model to investigate genes involved in muscle development and degeneration, including human muscular dystrophy (12-18). The orthologs of many dystrophin-glycoprot...