|Budget Amount *help
¥2,300,000 (Direct Cost : ¥2,300,000)
Fiscal Year 1996 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1995 : ¥1,700,000 (Direct Cost : ¥1,700,000)
Role of angiotensin and bcl-2 on renal organogenesis was investigated using recently established angiotensinogen and bcl-2 gene desrupted mice.
1)Angiotensin deficient mice.
Embryonic kidneys in Atg -/- mice from E13 to E18 exhibited active nephrogenesis, as also observed in Atg +/- mice and Atg +/+ mice. Futhermore, metanephroi harvested at E12 from Atg -/- embryos showed similar branching morphogenesis of ureteric bud and tubulogenesis as metanephroi from Atg -/- embryos grown with exogenous angiotensin II.In newborn Atg -/- mice, we observed unifrom dilatation of the pelvis accompanied by a coarse medulla. Hydronephrosis continued and renal papillae underwent atrophy for the 4 weeks after birth. Moreover, hickening of vascular walls as little as two weeks after birth was impressive. in situ hybridization and immunohistochemistry demonctrated that expression of renin mRNA became prominent in parallel with hyperplasia of VSMC,as well as recruitment of renin protein. In conclusion, the r
enin-angiotensin system appears not be essential for nephrogenesis in vivo. Furthermore, hyperplasia of VSMC and expression of the smoothmuscle phenotype in the mesangium are inducible even in the absence of angiotensin II,with hypotension, in vivo.
2)bcl-2 deficient mice
Extensive apoptosis occurred during abnormal nephrogenesis in bcl-2 deficient mice. In bcl-2 -/- mice, initial induction of nephron was detected by embryonic day 13 (E-13) as normal. Then, apoptotic cells became five times more frequent at E-13 to E-16 with a significant reduction (1/5) in nephron number at E-17 to E-19 in bcl-2 -/- mice compared to bcl-2 +/+ mice. No morphological difference was evident between bcl-2 +/- mice and bcl-2 +/+ mice by morphometry. Apoptotic cells were found mainly among the mesenchyme and less frequently in tubuli. Little apoptosis among ureteric buds was noted. In bcl-2 -/- mice at E-17 to E-19, inactive branching and insufficient convolution of ureteric buds were accompanied by fulminant apoptosis in the mesenchyme. Neonatal bcl-2 -/- mice lacked the nephrogenic zone, exhibiting renal hypoplasia. Thus, bcl-2 seems to inhibit apoptosis in renal stem cells during the induction of nephron in vivo. Less