Different roles of N- and C- termini in the functional activity of FGF21.

Fibroblast growth factor 21 is a member of endocrine FGFs subfamily, along with FGF19 and FGF23. It is emerging as a novel regulator with beneficial effects on a variety of metabolic parameters, including glucose and lipid control. FGF21 activity depends on membrane protein betaKlotho that physically complexes with various FGF receptors, thus conferring them the ability to bind FGF21 and activate downstream signaling pathways. FGF21, like other FGFs, folds to a beta-trefoil-like core region, with disordered N- and C-termini. In order to investigate their role in the activity of FGF21, we have constructed a series of deletion mutants and tested them for their ability to (1) bind betaKlotho, analyzed by surface plasmon resonance spectroscopy (2) signal through MAPK phosphorylation and inhibit apoptosis in 3T3-L1/betaKlotho fibroblasts (3) stimulate GLUT1 mRNA upregulation and glucose uptake in 3T3-L1 adipocytes. Binding studies with betaKlotho revealed that the interaction with the co-receptor involves the C-terminus, as progressive removal of amino acids from the carboxy end decreased affinity for betaKlotho. By contrast, removal of up to 17 amino acids from the N-terminus had no effect on the interaction with betaKlotho. Terminal deletions had greater effect on function, as deletions of six amino acids from the amino-terminus and only four from the carboxy-terminus each significantly impacted activity (10-fold). Of the extreme terminal truncations, with no detectable activity, DeltaN17 acted as competitive antagonist while DeltaC20 did not. Our structure/function studies show that the C-terminus is important for betaKlotho interaction whereas the N-terminus likely interacts directly with FGF receptors.

Enhanced potency of plasmid DNA microparticle human immunodeficiency virus vaccines in rhesus macaques by using a priming-boosting regimen with recombinant proteins.

DNA vaccines have been used widely in experimental primate models of human immunodeficiency virus (HIV), but their effectiveness has been limited. In this study, we evaluated three technologies for increasing the potency of DNA vaccines in rhesus macaques. These included DNA encoding Sindbis virus RNA replicons (pSINCP), cationic poly(lactide-co-glycolide) (PLG) microparticles for DNA delivery, and recombinant protein boosting. The DNA-based pSINCP replicon vaccines encoding HIV Gag and Env were approximately equal in potency to human cytomegalovirus (CMV) promoter-driven conventional DNA vaccines (pCMV). The PLG microparticle DNA delivery system was particularly effective at enhancing antibody responses induced by both pCMV and pSINCP vaccines and had less effect on T cells. Recombinant Gag and Env protein boosting elicited rapid and strong recall responses, in some cases to levels exceeding those seen after DNA or DNA/PLG priming. Of note, Env protein boosting induced serum-neutralizing antibodies and increased frequencies of gamma interferon-producing CD4 T cells severalfold. Thus, PLG microparticles are an effective means of delivering DNA vaccines in nonhuman primates, as demonstrated for two different types of DNA vaccines encoding two different antigens, and are compatible for use with DNA prime-protein boost regimens.