The yeast RNA1 protein, necessary for RNA processing, is homologous to the human ribonuclease/angiogenin inhibitor (RAI)

From housekeeper to microsurgeon: the diagnostic and therapeutic potential of ribonucleases

The RNA population in cells is controlled post-transcriptionally by ribonucleases (RNases) of varying specificity. Angiogenin, neurotoxins, and plant allergens are among many proteins with RNase activity or significant homology to known RNases. RNase activity in serum and cell extracts is elevated in a variety of cancers and infectious diseases. RNases are regulated by specific activators and inhibitors, including interferons. Many of these regulatory molecules are useful lead compounds for the design of drugs to control tumor angiogenesis, allergic reactions, and viral replication. One RNase (Onconase) and several RNase activators are now in clinical trials for cancer treatment or inhibition of chronic virus infections. Several others, alone or conjugated with specific cell binding molecules, are being developed for their antifungal, antiviral, and antitumor cell activity.

Ribonuclease inhibitors in human blood: comparative studies on the inhibitors detected in erythrocytes, platelets, mononuclear leukocytes and granulocytes

The erythrocyte ribonuclease inhibitor (RI) and platelet RI were separately purified to homogeneity and showed similar properties to those of human brain and placental RIs. The same type of RI seemed to be present in mononuclear leukocytes and granulocytes. The RI contents of these cells were detectable by immunoblot analysis using anti-human placental RI antibody. Neither RI activity nor the molecule cross-reactive with the anti-human placental RI antibody was detectable in any plasma sample. It is intriguing to detect active RI in mature erythrocytes, where no nucleus exists and RNA metabolism is unlikely to occur.

Recombinant expression and domain structure of the Rna1 protein from Schizosaccharomyces pombe

The amino acid sequence of Rna1p, a yeast protein implicated in the maturation and/or nucleocytoplasmic transport of RNA, is characterised by the presence of eight leucine-rich repeats (LLRs) as well as two intervening repeats of a different type and a highly acidic C-terminal region. Limited proteolysis of purified Rna1p expressed recombinantly in bacteria reveals that the C-terminal extension but not the region containing the two types of repeats is highly accessible to proteolytic attack and that the C-terminal region most likely harbours (a) low affinity Ca(2+)-binding site(s). These results are indicative of the domain structure of the Rna1p molecule, with the repeats and the C-terminal region being accessible for different interactions.

Angiogenesis inhibition: a review

In this review we discuss the concept of anti-angiogenesis, which is the inhibition of neovascularization. Anti-angiogenic agents are viewed from the standpoint of their effect on various elements of the angiogenic process, including induction of vascular discontinuity, endothelial cell movement, endothelial cell proliferation, and three-dimensional restructuring of patent vessels. An effort is made to place the many different approaches to anti-angiogenesis research into a comprehensible structure, in order to identify problems of evaluation and interpretation, thereby providing a clearer basis for determining promising and needed directions for further investigation.

A murine homolog of the yeast RNA1 gene is required for postimplantation development

A gene has been characterized that is required for postimplantation mouse development. The gene, designated fug1, was disrupted in embryonic stem cells by the U3Neo gene trap retrovirus, and the disrupted allele was introduced into the germ line. Homozygous mutant embryos arrest at the egg cylinder stage at about embryonic day 6 and are mostly resorbed by day 8.5. The appearance of the proamniotic cavity is delayed, and epiblast cells that surround the cavity are disorganized. fug1 transcripts are undetectable at E6 but are induced throughout the embryo after E6.5. The gene is expressed at low levels in all adult tissues examined, maps to chromosome 15, and is conserved among mammals. The cDNA sequence encodes a protein of 589 amino acids, the first 400 of which are 38% identical to the Saccaromyces cerevisiae RNA1 gene. Regions of greatest similarity include a long acidic domain and 11 leucine-rich motifs, thought to mediate high affinity protein-protein interactions. These similarities suggest that Fug1 may be required for developmental changes in RNA processing or chromatin structure prior to gastrulation.