A protein RNase inhibitor (RNasin) expresses anti-angiogenic properties in mice

Angiogenin is a protein which in addition to its ability to induce angiogenesis can function as a ribonuclease [1]. 1 First described and isolated by Vallee and his collaborators, it has since been fully sequenced and subjected to extensive biochemical analysis. Angiogenin is a potent angiogenesis-inducing molecule. Angiogenin shows selective ribonuclease activity, readily breaking down tRNA but yielding larger intermediate fragments than pancreatic ribonulease A when acting on 18S or 28S RNA. Angiogenin has been synthesized by recombinant technology and site-specific mutagenesis studies have been carried out to help identify those moieties significant for ribonuclease and angiogenic activity of the molecule. Interestingly, while in most instances the efficacy of angiogenin as an angiogenesis inducer and as a ribonuclease were correlated, mutants have now been identified which show an increase in ribonuclease activity with a concomitant decrease in angiogenic activity. Recently, Vallee and his colleagues have suggested that the Rnase active site is required but not sufficient for angiogenic activity and that a second site on the molecule is required in addition [2]. What mechanism allows angiogenin to act as an inducer of new blood vessel formation is not known, although binding studies suggest that angiogenin can act directly on endothelial cell targets. These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.