title: Renalase Secreted by Human Kidney HEK293T Cells Lacks its N-Terminal Peptide: Implications for Putative Mechanisms of Renalase Action.
abstract: OBJECTIVE
  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.
authors: Institute of Biomedical Chemistry, Moscow, Russia.
authors: Valerii
authors: V
authors: Fedchenko
authors: Arthur
authors: A
authors: Kopylov
authors: Nadezhda
authors: N
authors: Kozlova
authors: Olga
authors: O
authors: Buneeva
authors: Alexei
authors: A
authors: Kaloshin
authors: Victor
authors: V
authors: Zgoda
authors: Alexei
authors: A
authors: Medvedev
mesh_terms: D005182:Flavin-Adenine Dinucleotide / Q000378:metabolism; D015870:Gene Expression; D018014:Gene Transfer Techniques; D057809:HEK293 Cells; D006801:Humans; D008995:Monoamine Oxidase / Q000235:genetics / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism*
chemical_list: D010446:Peptide Fragments; D005182:Flavin-Adenine Dinucleotide; D008995:Monoamine Oxidase; C521557:renalase