Over-expression of adenosine deaminase in mouse podocytes does not reverse puromycin aminonucleoside resistance.
BACKGROUND
Edema in nephrotic syndrome results from renal retention of sodium and alteration of the permeability properties of capillaries. Nephrotic syndrome induced by puromycin aminonucleoside (PAN) in rats reproduces the biological and clinical signs of the human disease, and has been widely used to identify the cellular mechanisms of sodium retention. Unfortunately, mice do not develop nephrotic syndrome in response to PAN, and we still lack a good mouse model of the disease in which the genetic tools necessary for further characterizing the pathophysiological pathway could be used. Mouse resistance to PAN has been attributed to a defect in glomerular adenosine deaminase (ADA), which metabolizes PAN. We therefore attempted to develop a mouse line sensitive to PAN through induction of normal adenosine metabolism in their podocytes.


METHODS
A mouse line expressing functional ADA under the control of the podocyte-specific podocin promoter was generated by transgenesis. The effect of PAN on urinary excretion of sodium and proteins was compared in rats and in mice over-expressing ADA and in littermates.


RESULTS
We confirmed that expression of ADA mRNAs was much lower in wild type mouse than in rat glomerulus. Transgenic mice expressed ADA specifically in the glomerulus, and their ADA activity was of the same order of magnitude as in rats. Nonetheless, ADA transgenic mice remained insensitive to PAN treatment in terms of both proteinuria and sodium retention.


CONCLUSIONS
Along with previous results, this study shows that adenosine deaminase is necessary but not sufficient to confer PAN sensitivity to podocytes. ADA transgenic mice could be used as a background strain for further transgenesis.
Brideau
Gaëlle
G
Université Pierre et Marie Curie, Institut National de la Santé et de la Recherche Médicale, Centre National de Recherche Scientifique, Paris, France.
Doucet
Alain
A
D000243:Adenosine Deaminase / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D000818:Animals; D004351:Drug Resistance; D004487:Edema / Q000209:etiology; D004790:Enzyme Induction; D005813:Genes, Synthetic; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics; D007678:Kidney Glomerulus / Q000201:enzymology; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D009318:Natriuresis / Q000187:drug effects; D009404:Nephrotic Syndrome / Q000139:chemically induced* / Q000150:complications / Q000201:enzymology; D050199:Podocytes / Q000187:drug effects* / Q000201:enzymology; D011401:Promoter Regions, Genetic / Q000235:genetics; D011507:Proteinuria / Q000188:drug therapy / Q000209:etiology; D011692:Puromycin Aminonucleoside / Q000494:pharmacology* / Q000633:toxicity; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000502:physiology; D013045:Species Specificity
D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; C407223:NPHS2 protein; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; C113267:nephrin; D011692:Puromycin Aminonucleoside; C548483:Ada protein, mouse; C548484:Ada protein, rat; D000243:Adenosine Deaminase