RNase 1 genes from the family Sciuridae define a novel rodent ribonuclease cluster

Comparative functional analysis of ribonuclease 1 homologs: molecular insights into evolving vertebrate physiology

Pancreatic-type ribonucleases (ptRNases) comprise a class of highly conserved secretory endoribonucleases in vertebrates. The prototype of this enzyme family is ribonuclease 1 (RNase 1). Understanding the physiological roles of RNase 1 is becoming increasingly important, as engineered forms of the enzyme progress through clinical trials as chemotherapeutic agents for cancer. Here, we present an in-depth biochemical characterization of RNase 1 homologs from a broad range of mammals (human, bat, squirrel, horse, cat, mouse, and cow) and nonmammalian species (chicken, lizard, and frog). We discover that the human homolog of RNase 1 has a pH optimum for catalysis, ability to degrade double-stranded RNA, and affinity for cell-surface glycans that are distinctly higher than those of its homologs. These attributes have relevance for human health. Moreover, the functional diversification of the 10 RNase 1 homologs illuminates the regulation of extracellular RNA and other aspects of vertebrate evolution.

Expression Patterns and Functional Novelty of Ribonuclease 1 in Herbivorous Megalobrama amblycephala

Ribonuclease 1 (RNase1) is an important digestive enzyme that has been used to study the molecular evolutionary and plant-feeding adaptation of mammals. However, the expression patterns and potential biological function of RNase1 in herbivorous fish is not known. Here, we identified RNase1 from five fish species and illuminated the functional diversification and expression of RNase1 in herbivorous Megalobrama amblycephala. The five identified fish RNase1 genes all have the signature motifs of the RNase A superfamily. No expression of Ma-RNase1 was detected in early developmental stages but a weak expression was detected at 120 and 144 hours post-fertilization (hpf). Ma-RNase1 was only expressed in the liver and heart of one-year-old fish but strongly expressed in the liver, spleen, gut, kidney and testis of two-year-old fish. Moreover, the immunostaining localized RNase1 production to multiple tissues of two-year-old fish. A biological functional analysis of the recombinant protein demonstrated that M. amblycephala RNase1 had a relatively strong ribonuclease activity at its optimal pH 6.1, which is consistent with the pH of its intestinal microenvironment. Collectively, these results clearly show that Ma-RNase1 protein has ribonuclease activity and the expression patterns of Ma-RNase1 are dramatically different in one year and two-year-old fish, suggesting the functional differentiation during fish growing.