Expressions Of Subtypes Of TGF-β Receptors In Rats With Unilateral Ureteral Obstruction

Objective: To investigate the expressive changes of the subtypes of TGF-βreceptors (ALK-5, ALK-6, ALK–7, TGFβR-Ⅱ) in the renal interstitial fibrosis induced by unilateral ureteral obstruction (UUO).Methods: Rats were divided randomly into three groups, i.e, normal control(CON), sham operation(SOR) and UUO groups, and sacrificed at postoperative day1, 3, 7, 14 and 21. Firstly, we use Real time-PCR Arrays to detect the mRNAs expressions of TGFβR-Ⅰ's and TGFβR-Ⅱ's subtypes and selected the candidate subtypes which were significantly changed among the three groups, that is ALK-5, ALK-6, ALK–7 and TGFβR-Ⅱ, then we further detected and confirmed the expression changes of above-mentioned TGFβreceptors by Real time-PCR, Western blot and immunofluorescence. Serum creatine was used to assess renal function. The histological changes of renal interstitial tissues were observed by PAS staining.Results: Blood biochemistry results showed that the serum creatinine, and blood urea nitrogen in UUO groups were gradually increased with the extension of time after operation and higher than that of CON group (P<0.05). PCR Arrays indicated that the mRNA expressions of TGF-βreceptors: TGFβR-Ⅱ, ALK-5, ALK-6, ALK-7 and Smad2,Smad3 changed significantly in the UUO group compared with the control group. The mRNA levels of ALK-5, ALK-7, TGFβR-Ⅱwere significantly increased in UUO rats detected by real-time RT-PCR(P<0.05). Western blot showed that the expression of ALK-6 significantly decreased in UUO group compared with CON group (P<0.05), whereas, the expressions of ALK-5, ALK-7, TGFβR-Ⅱwere obviously increased. The protein levels of Smad2/3, p-Smad2/3 were significantly increased. The results of immunofluorescence indicate that ALK-5, ALK-6, ALK-7, TGFβR-Ⅱwere mainly expressed in renal tubular and interstitial, rarely in glomeruli. In UUO rats, the protein expressions of ALK-5, ALK-7, TGFβR-Ⅱincreased and ALK-6 decreased in varying degrees according to the post-operated days.Conclusion: The expressions of TGF-βreceptor subtypes ALK-5, ALK-7 and TGFβR -Ⅱincreased while the expression of ALK-6 decreased during the progress of renal tubulointerstitial fibrosis and all of these had a time-space consistency.