Pk. Grover et al., Prothrombin gene expression in rat kidneys provides an opportunity to examine its role in urinary stone pathogenesis, J AM S NEPH, 10, 1999, pp. S404-S407
Urinary form of prothrombin (PT) fragment 1 is the most abundant protein in
calcium oxalate crystals generated in human urine. The protein has also be
en detected in human calcium-containing stones. In its purified form, the p
rotein inhibits calcium oxalate crystal growth and, more importantly, aggre
gation in aqueous inorganic solutions and undiluted human urine. Recently,
PT gene expression has been reported in human kidneys. However, access to h
uman renal tissue for studies is limited, and it is not possible to easily
manipulate PT biosynthesis in human subjects. The aim of this investigation
, therefore, was to determine whether PT gene expression is present in rat
kidneys. Samples of total RNA were isolated from the kidneys and livers (po
sitive controls) of 12 male hooded Wister rats. Using reverse transcription
-PCR, mRNA corresponding to the thrombin and F1+2 regions of PT was analyze
d by agarose gel electrophoresis. The expression of the "housekeeping" gene
glyceraldehyde-3-phosphate dehydrogenase was also examined, to determine t
he availability of amplifiable substrate in each specimen. The amplified pr
oducts were also sequenced, to determine their identities. All rat kidneys
displayed evidence of expression of the thrombin and F1+2 domains of the PT
gene. This similarity between human and rat kidneys allows the possibility
of using established rat models of stone disease to evaluate therapeutic s
trategies to reduce stone formation.