Renalase is a recently discovered protein, involved in regulation of blood pressure in humans and animals. Although several splice variants of human renalase mRNA transcripts have been recognized, only one protein product, hRenalase1, has been found so far. In this study, we have used polymerase chain reaction (PCR)-based amplification of individual exons of the renalase gene and their joining for construction of full-length hRenalase2 coding sequence followed by expression of hRenalase2 as a polyHis recombinant protein in Escherichia coli cells. To date this is the first report on synthesis and purification of hRenalase2. Applicability of this approach was verified by constructing hRenalase1 coding sequence, its sequencing and expression in E. coli cells. hRenalase1 was used for generation of polyclonal antiserum in sheep. Western blot analysis has shown that polyclonal anti-renalase1 antibodies effectively interact with the hRenalase2 protein. The latter suggests that some functions and expression patterns of hRenalase1 documented by antibody-based data may be attributed to the presence of hRenalase2. The realized approach may be also used for construction of coding sequences of various (especially weakly expressible) genes, their transcript variants, etc.

Background/Aims: Renalase is a recently discovered flavoprotein involved in regulation of blood pressure. Altered renalase levels have been found in blood of patients with end stage renal disease. The antihypertensive effect of circulating renalase is attributed to putative FAD-dependent monoamine oxidase activity demonstrated by some authors. Being synthesized as an intracellular flavoprotein renalase requires the presence of its N-terminal peptide for FAD accommodation. However, conventional routes of export of secretory proteins outside the cell usually include cleavage of their N-terminal peptide. The aim of this study was to investigate whether renalase is secreted by НЕK293T cells as a full length protein (via proposed nonconventional pathway) or its export is accompanied by the loss of its N-terminal peptide. Methods: We have expressed human recombinant renalase-1 in human kidney НЕK293T cells and analyzed this protein inside the cells and in the extracellular medium for the presence of the N-terminal peptide by using high resolution targeted MS/MS. Results: Intracellular renalase contained clearly detectable N-terminal peptide, which was absent in extracellular renalase. Conclusions: Lack of the N-terminal peptide, the structural precondition for FAD binding, suggests that extracellular (circulating) renalase acts in a FAD-independent manner and mechanisms of its action are not associated with FAD.

A simplified «exon» method was developed for producing cDNA of low-copy and silent eukaryotic genes. It is based on assembly of the target gene from genomic DNA by direct synthesis of its exons, followed by their PCR-based joining without further purification of the amplicons. During the synthesis of exons, direct primers were used; these included about ~ 20 nucleotides of the 3`-terminal sequence previous (from the amplified) exon and ~ 20 nucleotides of the 5`-initial sequence of the amplified exon. Reverse primers included ~ 20 nucleotides complementary to the terminal sequence of the amplified exon. Forward and reverse primers flanking the gene to be assembled included the restriction sites necessary for insertion into the expression vector. Using this approach it is possible to assemble almost any eukaryotic gene with a known nucleotide sequence of genomic DNA available in the database.

Renalase (RNLS) is a recently discovered protein that plays different roles inside and outside cells. Extracellular RNLS exhibits protective effects on the cell, acting on its receptor proteins, while intracellular RNLS acts as FAD-dependent oxidoreductase (EC 1.6.3.5). The ratio of the intracellular and extracellular forms of this protein, as well as the mechanisms and factors responsible for its transport from the cell, remain unknown. One of the approaches to studying these issues can be the creation of chimeric forms of this protein with modified fragments of its amino acid sequences. This work describes a method for constructing a chimeric human RNLS gene encoding RNLS without its N-terminal peptid

Renalase is a recently discovered secretory protein, which is suggested to play a role (which still remains elusive) in regulation of blood pressure. Earlier it was purified from urine of healthy volunteers by means of ammonium sulfate fractionation and subsequent affinity chromatography (Xu et al. (2005) J. Clin. Invest., 115, 1275). The resultant purified preparation of renalase contained 2 proteins with molecular masses of 35 and 67-75 kDa. The authors believed that the latter represents a dimerization (aggregation) product of the 35 kDa protein. In this study we have detected relanase in urinary samples of 2 of 6 volunteers only after immunoaffinity enrichment of urinary samples subjected to ammonium sulfate precipitation. Electrophoresis of the purified preparation also demonstrated the presence of 2 proteins with molecular masses of 35 and 66 kDa, respectively. Mass spectrometry analysis of these proteins identified 35 and 66 kDa proteins as renalase and serum albumin, respectively. Thus, our results do not support suggestion on formation of renalase dimers and they indicate that urinary renalase excretion significantly varies in humans.