title: Intra-renal and urinary mRNA expression of podocyte-associated molecules for the estimation of glomerular podocyte loss.
abstract: BACKGROUND
  Podocyte loss plays an important role in the pathogenesis of diabetic nephropathy, but counting the number of glomerular podocyte in renal biopsy specimen is a labor-intensive task. We study whether intra-renal and urinary messenger RNA expression of podocyte-associated molecules could be used to estimate glomerular podocyte number in patients with diabetic nephropathy.
  
  
  METHODS
  We studied 21 consecutive patients with biopsy-proven diabetic nephropathy. The intra-renal and urinary mRNA expression of nephrin, podocin, and synaptopodin were measured by real-time quantitative polymerase chain reaction. Podocyte number was determined in micro-dissected glomerulus. The degree of histological scarring was quantified by morphometric analysis.
  
  
  RESULTS
  Glomerular podocyte number correlated with intra-renal expression of nephrin (r=0.510, p=0.044), podocin (r=0.605, p=0.013), and synaptopodin (r=0.480, p=0.060). Glomerular podocyte number also significantly correlated with urinary expression of synaptopodin (r=0.595, p=0.019) but not other targets. Baseline renal function correlated with intra-renal expression of nephrin (r=0.617, p=0.005), synaptopodin (r=0.474, p=0.040), and podocin (r=0.443, p=0.057). The degree of tubulointerstitial scarring also inversely correlated with intra-renal expression of nephrin (r=-0.462, p=0.047), podocin (r=-0.458, p=0.049), and synaptopodin (r=-0.500, p=0.029) but not with urinary gene expression.
  
  
  CONCLUSIONS
  Intra-renal expression of podocyte-associated molecules correlated with glomerular podocyte number, renal function, and tubulointerstitial scarring. The results suggest that intra-renal, but not urinary expression of podocyte-associated molecules, might be used to assess the degree of podocyte loss in diabetic nephropathy.
authors.affiliation: Department of Medicine and Therapeutics, Prince of Wales Hospital, Chinese University of Hong Kong, Shatin, Hong Kong, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Wang
authors.forename: Fernand Mac-Moune
authors.initials: FM
authors.lastname: Lai
authors.forename: Ka-Bik
authors.initials: KB
authors.lastname: Lai
authors.forename: Kai-Ming
authors.initials: KM
authors.lastname: Chow
authors.forename: Bonnie Ching-Ha
authors.initials: BC
authors.lastname: Kwan
authors.forename: Kam-Tao Philip
authors.initials: KT
authors.lastname: Li
authors.forename: Cheuk-Chun
authors.initials: CC
authors.lastname: Szeto
mesh_terms: D001706:Biopsy; D003928:Diabetic Nephropathies / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D007668:Kidney / Q000378:metabolism*; D007678:Kidney Glomerulus / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism*; D008875:Middle Aged; D050199:Podocytes / Q000378:metabolism / Q000473:pathology*; D012333:RNA, Messenger / Q000378:metabolism* / Q000652:urine
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D008840:Microfilament Proteins; C407223:NPHS2 protein; D012333:RNA, Messenger; C503967:SYNPO protein, human; C113267:nephrin