Fibroblast growth factor 21 (FGF21) is a promising drug candidate for the treatment of type 2 diabetes. However, the use of wild type native FGF21 is challenging due to several limitations. Among these are its short half-life, its susceptibility to in vivo proteolytic degradation and its propensity to in vitro aggregation. We here describe a rationale-based protein engineering approach to generate a potent long-acting FGF21 analog with improved resistance to proteolysis and aggregation. A recombinant Fc-FGF21 fusion protein was constructed by fusing the Fc domain of human IgG1 to the N-terminus of human mature FGF21 via a linker peptide. The Fc positioned at the N-terminus was determined to be superior to the C-terminus as the N-terminal Fc fusion retained the βKlotho binding affinity and the in vitro and in vivo potency similar to native FGF21. Two specific point mutations were introduced into FGF21. The leucine to arginine substitution at position 98 (L98R) suppressed FGF21 aggregation at high concentrations and elevated temperatures. The proline to glycine replacement at position 171 (P171G) eliminated a site-specific proteolytic cleavage of FGF21 identified in mice and cynomolgus monkeys. The derived Fc-FGF21(RG) molecule demonstrated a significantly improved circulating half-life while maintaining the in vitro activity similar to that of wild type protein. The half-life of Fc-FGF21(RG) was 11 h in mice and 30 h in monkeys as compared to 1-2 h for native FGF21 or Fc-FGF21 wild type. A single administration of Fc-FGF21(RG) in diabetic mice resulted in a sustained reduction in blood glucose levels and body weight gains up to 5-7 days, whereas the efficacy of FGF21 or Fc-FGF21 lasted only for 1 day. In summary, we engineered a potent and efficacious long-acting FGF21 analog with a favorable pharmaceutical property for potential clinical development.
Web service discovery is a key problem as the number of services is expected to increase dramatically. Service discovery at the present time is based primarily on keywords, or interfaces of web services through the use of ontology. We argue that "behavior signatures" as operational level description should play an important role in the service discovery process. In this paper, we propose a new behavior model for web services using automata and logic formalisms. Roughly, the model associates messages with activities and adopts the IOPR model in OWLS to describe activities. A new query language is developed to express temporal and semantic properties on service behaviors. Query evaluation algorithms are developed; in particular, an optimization approach using RE-tree and heuristics is shown to improve the performance. Specifically, experimental results show that the use of RE-tree reduces query evaluation time by an order of magnitude and with heuristics it enhances the performance by two orders of magnitude. This is clearly an encouraging starting point.
The main objective of composing web services is to identify usable web services through discovery and to orchestrate or assemble selected services according to the goal specification. In this paper, we formulate and study a framework of composing web services through discovery from a given goal service. A general algorithm for composition with or without a goal service invocation request is developed. Two notions of completeness, "schema completeness" and "instance completeness", are defined, which measure the ability of how thoroughly an algorithm can find a composition. The two notions correspond to compositions without or with a goal service request, resp. We show that schema completeness can be achieved by depth-first or breadth-first search combined with a tightening strategy. Further, the breadth-first search avoids redundancy. We also show that while instance complete algorithms exist, they generally need do invoke all candidate services.
We develop a framework to compose services through discovery and orchestration for a given goal service. Tightening techniques are used in composition algorithms to achieve "completeness".
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