Extracellular and circulating redox- and metalloregulated eRNA and eRNP: copper ion-structured RNA cytokines (angiotropin ribokines) and bioaptamer targets imparting RNA chaperone and novel biofunctions to S100-EF-hand and disease-associated proteins

Influence of Extracellular RNAs, Released by Rheumatoid Arthritis Synovial Fibroblasts, on Their Adhesive and Invasive Properties

Extracellular RNA (exRNA) has been characterized as a molecular alarm signal upon cellular stress or tissue injury and to exert biological functions as a proinflammatory, prothrombotic, and vessel permeability-regulating factor. In this study, we investigated the contribution of exRNA and its antagonist RNase1 in a chronic inflammatory joint disease, rheumatoid arthritis (RA). Upon immunohistochemical inspection of RA, osteoarthritis (OA), and psoriatic arthritis synovium, exRNA was detectable only in the RA synovial lining layer, whereas extracellular DNA was detectable in various areas of synovial tissue. In vitro, exRNA (150-5000 nt) was released by RA synovial fibroblasts (RASF) under hypoxic conditions but not under normoxia or TNF-α treatment. RNase activity was increased in synovial fluid from RA and OA patients compared with psoriatic arthritis patients, whereas RNase activity of RASF and OASF cultures was not altered by hypoxia. Reduction of exRNA by RNase1 treatment decreased adhesion of RASF to cartilage, but it had no influence on their cell proliferation or adhesion to endothelial cells. In vivo, treatment with RNase1 reduced RASF invasion into coimplanted cartilage in the SCID mouse model of RA. We also analyzed the expression of neuropilins in synovial tissue and SF, as they may interact with vascular endothelial growth factor signaling and exRNA. The data support the concepts that the exRNA/RNase1 system participates in RA pathophysiology and that RASF are influenced by exRNA in a prodestructive manner.

The Features of Copper Metabolism in the Rat Liver during Development

Strong interest in copper homeostasis is due to the fact that copper is simultaneously a catalytic co-factor of the vital enzymes, a participant in signaling, and a toxic agent provoking oxidative stress. In mammals, during development copper metabolism is conformed to two types. In embryonic type copper metabolism (ETCM), newborns accumulate copper to high level in the liver because its excretion via bile is blocked; and serum copper concentration is low because ceruloplasmin (the main copper-containing protein of plasma) gene expression is repressed. In the late weaning, the ETCM switches to the adult type copper metabolism (ATCM), which is manifested by the unlocking of copper excretion and the induction of ceruloplasmin gene activity. The considerable progress has been made in the understanding of the molecular basis of copper metabolic turnover in the ATCM, but many aspects of the copper homeostasis in the ETCM remain unclear. The aim of this study was to investigate the copper metabolism during transition from the ETCM (up to 12-days-old) to the ATCM in the rats. It was shown that in the liver, copper was accumulated in the nuclei during the first 5 days of life, and then it was re-located to the mitochondria. In parallel with the mitochondria, copper bulk bound with cytosolic metallothionein was increased. All compartments of the liver cells rapidly lost most of their copper on the 13^th day of life. In newborns, serum copper concentration was low, and its major fraction was associated with holo-Cp, however, a small portion of copper was bound to extracellular metallothionein and a substance that was slowly eluted during gel-filtration. In adults, serum copper concentration increased by about a factor of 3, while metallothionein-bound copper level decreased by a factor of 2. During development, the expression level of Cp, Sod1, Cox4i1, Atp7b, Ctr1, Ctr2, Cox17, and Ccs genes was significantly increased, and metallothionein was decreased. Atp7a gene’s activity was fully repressed. The copper routes in newborns are discussed.

Extracellular functional noncoding nucleic acid bioaptamers and angiotropin RNP ribokines in vascularization and self-tolerance

Endogenous extracellular and circulating functional small noncoding nucleic acids (ncNAs; <200 nucleotides) and complexes with proteins (ribonucleoproteins; RNPs) make up varying biolibraries of molecular imprints of cellular histories. They are nascently formed upon cellular activation by extrinsic (environmental) factors, including mitogens, cell-mediated immune memory reactions (Landsteiner-Chase-Lawrence transfer factors), and metabolic (hypoxia) and (physical) shear stress forces. Those factors are conventional models for epigenetic (non-Mendelian) vascular remodeling variations directed rather to proteinaceous gene expression and regulation than genomic DNA sequence changes. Structurally defined ncNAs are described as small hairpin nc-shRNA bioaptamers in interaction with proteins forming functional (Cu,Ca,Na,K)-metalloregulated complexes (CuRNP; angiotropins). As nonmitogenic angiomorphogen cytokines (ribokines), they may reprogram confluent quiescent (contact-inhibited) endothelial cell types to migratory, phagokinetically active phenotypes in the morphogenesis of tolerated neovascular patterns. Their functions in organized and mess-chaotic vascular patterns were investigated with regard to master gene, information, epigenetic, vascular, and tumor factors. Some ncNAs feature three-dimensional codes (3D episcripts) for distinct protein conformer phases. They are suggested as being specific recognition types, the estimated repertoires of which are superior in diversity and specificity to conventional immune (glyco-)proteins. For episcription of phenotype variations, they may address and integrate information flow on molecular shapes to protein-mediated nucleic acid processing and [post-]translational modification mechanisms in ncNA-, redox, and metalloregulated conformation phase pathway-locked loops (CPLL). Several vascular and cancer epigenetic regulator proteins are shown to be entangled by sharing helix-nucleating structural (proteomic) domains for interaction with functional nc-shRNA, termed K/RxxxH (K/R3H, -xK/RxxxHx(7-9)h/xx(7-9)h/xx(5-20)K/Rx-). This would suggest a tolerated mess-chaotic tumor vascularization as a bioaptamer disorder in ncNA-switched proteinaceous genetic and epigenetic processes.

Extracellular nucleic acids

Extracellular nucleic acids are found in different biological fluids in the organism and in the environment: DNA is a ubiquitous component of the organic matter pool in the soil and in all marine and freshwater habitats. Data from recent studies strongly suggest that extracellular DNA and RNA play important biological roles in microbial communities and in higher organisms. DNA is an important component of bacterial biofilms and is involved in horizontal gene transfer. In recent years, the circulating extracellular nucleic acids were shown to be associated with some diseases. Attempts are being made to develop noninvasive methods of early tumor diagnostics based on analysis of circulating DNA and RNA. Recent observations demonstrated the possibility of nucleic acids exchange between eukaryotic cells and extracellular space suggesting their participation in so far unidentified biological processes.