Receptors for Wingless and other signalling molecules of the Wnt gene family have yet to be identified. We show here that cultured Drosophila cells transfected with a novel member of the frizzled gene family in Drosophila, Dfz2, respond to added Wingless protein by elevating the level of the Armadillo protein. Moreover, Wingless binds to Drosophila or human cells expressing Dfz2. These data demonstrate that Dfz2 functions as a Wingless receptor, and they imply, in general, that Frizzled proteins are receptors for the Wnt signalling molecules.

We thank Dr. Clark Riley, Ms. Carol Davenport, and Ms. Jani ne Ptak for synthetic oligonucleotides; Dr. Keith Fry for the gift of mAb ABS; Ms. Cathy Blizzard for cat eyes; Dr. Mark Molliver for donating fixed monkey eyes; Drs. Masafumi Tanaka and Wi nshi p Herr for Oct.1 cDNA; Mr. Hao Zhou for the GST-Ott-1 POU domain protein; Dr. Y.-W. Peng for rabbit retinas and Dr. Hua-Shun Li for chicken retinas; Dr. Elio Ravi ol a for advice on histologic techniques; and Drs. Robert Rodieck, Jen-Chi h Hsieh, and King-wai Yau for hel pful comments on the manuscript.

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Four new members of the fibroblast growth factor (FGF) family, referred to as fibroblast growth factor homologous factors (FHFs), have been identified by a combination of random cDNA sequencing, data base searches, and degenerate PCR. Pairwise comparisons between the four FHFs show between 58% and 71% amino acid sequence identity, but each FHF shows less than 30%o identity when compared with other FGFs. Like FGF-1 (acidic FGF) and FGF-2 (basic FGF), the FHFs lack a classical signal sequence and contain clusters of basic residues that can act as nuclear localization signals. In transiently transfected 293 cells FHF-1 accumulates in the nucleus and is not secreted. Each FHF is expressed in the developing and adult nervous systems, suggesting a role for this branch of the FGF family in nervous system development and function.Fibroblast growth factors (FGFs) comprise a family of nine related polypeptides with broad mitogenic and cell survival activities (1-3). FGF-1 (acidic FGF) and FGF-2 (basic FGF), the first family members to be identified, purified, and sequenced, are widely expressed and are potent mitogens for a variety of cell types (4, 5). The gene encoding FGF-3 is a common target for activation by the mouse mammary tumor virus (6), and the genes encoding FGF-4, have transforming activity when introduced into NIH 3T3 cells (7-9). FGF-7, FGF-8, and FGF-9 are mitogens for keratinocytes, mammary carcinoma cells, and astrocytes, respectively (10-12). Recent experiments indicate that several FGFs have bioactivities that were not evident during their initial identification. For example, FGF-2 can induce ventral mesoderm in Xenopus embryos (13,14), FGF-4 is involved in growth and patterning of the chicken limb bud (15), FGF-5 controls hair follicle cycling in the mouse (16), and FGF-8 can cause duplications of the embryonic chicken midbrain (17).The nine known FGFs are between 155 and 268 amino acid residues in length and share a conserved central region of -140 amino acids. This region forms a compact (3-barrel with 3-fold symmetry that is nearly identical in structure to the folded core of interleukins-la and -13 (18-21). FGF-1 and FGF-2 also resemble interleukin-1,B in lacking a classical signal sequence. Current data indicate that FGF-1 and FGF-2 are released from cells by a route that is distinct from the endoplasmic reticulum-Golgi secretory pathway (22, 23).FGF signaling is generally assumed to occur by activation of transmembrane tyrosine kinase receptors. Four FGF receptor (FGFR) genes have been identified thus far (24), and activating or inactivating receptor mutations have been described for a subset of these genes in both mice and humans. In the mouse, disruption of the FGFR1 or FGFR2 genes leads to early embryonic lethality (25,26), and disruption of FGFR3 leads to bone overgrowth (27,28). In humans, point mutations in FGFR1, FGFR2, and FGFR3 have been found in a variety of skeletal disorders (reviewed in ref. 29).In this paper we report the identification and characterization of four new mem...

Many ligand/receptor families are known to contribute to axonal growth and targeting. Thus far, there have been no reports implicating Wnts and Frizzleds in this process, despite their large numbers and widespread expression within the CNS. In this study, we show that targeted deletion of the mouse fz3 gene leads to severe defects in several major axon tracts within the forebrain. In particular, fz3(-/-) mice show a complete loss of the thalamocortical, corticothalamic, and nigrostriatal tracts and of the anterior commissure, and they show a variable loss of the corpus callosum. Peripheral nerve fibers and major axon tracts in the more caudal regions of the CNS are mostly or completely unaffected. Cell proliferation in the ventricular zone and cell migration to the developing cortex proceed normally until at least embryonic day 14. Extensive cell death in the fz3(-/-) striatum occurs late in gestation, perhaps secondary to the nearly complete absence of long-range connections. In contrast, there is little cell death, as assayed by terminal deoxynucleotidyl transferase-mediated biotinylated UTP nick end labeling, in the cortex. These data provide the first link between Frizzled signaling and axonal development.

Expression of the yeast his3 and other amino acid biosynthetic genes is induced during conditions of amino acid starvation. The coordination of this response is mediated by a positive regulatory protein called GCN4, which binds specifically to regulatory sites upstream of all coregulated genes and stimulates their transcription. The nucleotide sequence requirements of the his3 regulatory site were determined by analysis of numerous point mutations obtained by a novel method of cloning oligonucleotides. Almost all single base pair mutations within the nine base pair sequence ATGACTCTT significantly reduce his3 induction in vivo and GCN4 binding in vitro, whereas changes outside this region have minimal effects. One mutation, which generates a sequence that most closely resembles the consensus for 15 coregulated genes, increases both the level of induction and the affinity for GCN4 protein. The palindromic nature of the optimal sequence, ATGACTCAT, suggest that GCN4 protein binds as a dimer to adjacent half-sites that possibly overlap.

In Drosophila melanogaster, the frizzled gene plays an essential role in the development of tissue polarity as assessed by the orientation of cuticular structures. Through a combination of random cDNA sequencing, degenerate polymerase chain reaction amplification, and low stringency hybridization we have identified six novel frizzled homologues from mammals, at least 11 from zebrafish, several from chicken and sea urchin, and one from Caenorhabditis elegans. The complete deduced amino acid sequences of the mammalian and nematode homologues share with the Drosophila frizzled protein a conserved amino-terminal cysteine-rich domain and seven putative transmembrane segments. Each of the mammalian homologues is expressed in a distinctive set of tissues in the adult, and at least three are expressed during embryogenesis. As hypothesized for the Drosophila frizzled protein, the frizzled homologues are likely to act as transmembrane receptors for as yet unidentified ligands. These observations predict the existence of a family of signal transduction pathways that are homologous to the pathway that determines tissue polarity in Drosophila.

CATNAP (Compile, Analyze and Tally NAb Panels) is a new web server at Los Alamos HIV Database, created to respond to the newest advances in HIV neutralizing antibody research. It is a comprehensive platform focusing on neutralizing antibody potencies in conjunction with viral sequences. CATNAP integrates neutralization and sequence data from published studies, and allows users to analyze that data for each HIV Envelope protein sequence position and each antibody. The tool has multiple data retrieval and analysis options. As input, the user can pick specific antibodies and viruses, choose a panel from a published study, or supply their own data. The output superimposes neutralization panel data, virus epidemiological data, and viral protein sequence alignments on one page, and provides further information and analyses. The user can highlight alignment positions, or select antibody contact residues and view position-specific information from the HIV databases. The tool calculates tallies of amino acids and N-linked glycosylation motifs, counts of antibody-sensitive and -resistant viruses in conjunction with each amino acid or N-glycosylation motif, and performs Fisher's exact test to detect potential positive or negative amino acid associations for the selected antibody. Website name: CATNAP (Compile, Analyze and Tally NAb Panels). Website address: http://hiv.lanl.gov/catnap.