New detection method for ribonuclease 2 (RNase 2) using immunoblotting with specific antibody

Nucleic acid degradation as barrier to gene delivery: a guide to understand and overcome nuclease activity

Gene therapy is on its way to revolutionize the treatment of both inherited and acquired diseases, by transferring nucleic acids to correct a disease-causing gene in the target cells of patients. In the fight against infectious diseases, mRNA-based therapeutics have proven to be a viable strategy in the recent Covid-19 pandemic. Although a growing number of gene therapies have been approved, the success rate is limited when compared to the large number of preclinical and clinical trials that have been/are being performed. In this review, we highlight some of the hurdles which gene therapies encounter after administration into the human body, with a focus on nucleic acid degradation by nucleases that are extremely abundant in mammalian organs, biological fluids as well as in subcellular compartments. We overview the available strategies to reduce the biodegradation of gene therapeutics after administration, including chemical modifications of the nucleic acids, encapsulation into vectors and co-administration with nuclease inhibitors and discuss which strategies are applied for clinically approved nucleic acid therapeutics. In the final part, we discuss the currently available methods and techniques to qualify and quantify the integrity of nucleic acids, with their own strengths and limitations.

Functional Insight into hTRIR

The uncharacterized C19orf43 was discovered to be associated with hTR maturation. Our previous work indicated that C19orf43 cleaves distinct RNA types but not DNA. We then named it hTR-interacting RNase (hTRIR) (Uniprot: Q9BQ61). hTRIR works in a broad range of temperatures and pH without any divalent cations needed. hTRIR cleaves RNA at all four nucleotide sites but preferentially at purines. In addition, hTRIR digested both ends of methylated small RNA, which suggested that it was a putative ribonuclease. Later, we designed more nucleotides that methylated small RNA to determine whether it was an exo- and/or endoribonuclease. Unlike RNase A, hTRIR could digest both ends of methylated RNA oligos 5R5, which suggested it was potentially an endoribonuclease.

Rabbit DNase I: purification from urine, immunological and proteochemical characterization, nucleotide sequence, expression in tissues, relationships with other mammalian DNases I and phylogenetic analysis

DNase I from rabbit urine was purified approx. 3600-fold to apparent homogeneity with a 41% yield by affinity chromatography utilizing DNA-cellulose; the purity of the final preparation was assessed by SDS/PAGE, lack of contamination by other nucleases and production of a monospecific antibody against the enzyme. Although the proteochemical and enzymological properties of the purified enzyme resembled those of other mammalian DNases I, the enzymic activity of rabbit DNase I was less efficiently inhibited by monomeric actin than was that of human DNase I, probably due to substitution of an amino acid residue involved in actin binding (Tyr-65 to Phe). The effects of specific antibodies to human, rabbit and rat DNases I on the activities of the corresponding purified enzymes revealed that human DNase I lies between the rat and rabbit enzymes with regard to its immunological properties. An 1158 bp full-length cDNA encoding rabbit DNase I was constructed from the total RNA of rabbit pancreas using a combination of reverse transcriptase-PCR and rapid amplification of cDNA ends, followed by sequencing. This identified a 17- or 21-amino-acid signal sequence, with the mature enzyme containing 260 amino acids and a single N-glycosylation site at Asn-18. The amino acid sequence deduced from the cDNA sequence exactly matched that determined proteochemically from the purified enzyme up to residue 20. A systematic survey of DNase I distribution as measured by both enzymic activity and DNase I gene transcripts in 12 rabbit tissues showed the pancreas and parotid gland to produce equivalent levels, higher than those in other tissues. Enzymic activity and DNase I gene expression levels in each tissue correlated well. The results of phylogenetic and sequence identity analysis, immunological properties and tissue-distribution patterns of DNase I indicated a closer relationship between the rabbit and human enzymes than for other mammalian DNases I. Furthermore, differences between the enzymic activities expressed in mammalian parotid gland and pancreas suggest that the distribution of DNase I in mammalian tissue is species-specific.

Forensic applications of genetic polymorphisms detected in human body fluids (urine, semen and blood)

The development of a new genetic marker with forensic usefulness is difficult and costly work, but it is necessary. We discovered several new markers detected in urine, semen and blood. In particular, deoxyribonuclease I-polymorphism is one of the most useful markers for practical purposes, since it has a well-balanced gene frequency, high concentration in body fluids, stability against severe conditions, and easy and accurate detectability.

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.

Immobilized pH gradient focusing of alkaline proteins: analysis of the isoform composition of purified human non-secretory ribonucleases from kidney, liver and spleen

Previous studies on the isoform composition of human ribonucleases (RNAases) have resulted in confusing and inconsistent results, presumably due to methodological problems in electrofocusing of alkaline proteins. In the present study, immobilized pH gradient (IPG) carrier ampholyte (CA) isoelectric focusing (IEF) and conventional CA-IEF have been evaluated for the analysis of the isoforms of human non-secretory RNAases purified from kidney, liver and spleen. CA-IEF proved unsuitable since the alkaline RNAase isoforms migrated into the cathode. IPG-CA-IEF, however, resolved the RNAase isoforms and marker proteins in the basic region of the gel matrix. The three RNAases had comparable isoform profiles, each with two protein bands with approximate pI values of 10.3 and 10.4. Western blotting showed that the two protein bands of each RNAase were immunoreactive (with polyclonal antibodies that recognize RNAase), indicating that the protein bands are RNAase isoforms. The present results provide reliable pI data on human RNAase isoforms and suggest that IPG-CA-IEF should be a suitable technique for analysing the isoforms of other alkaline proteins.