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A Modified Two Kidney One Clip Mouse Model of Renin Regulation in Renal Artery Stenosis
Published on: October 26, 2020
Upregulation of renal renin-angiotensin system in mouse diabetic nephropathy
Jun Tamura1, Akihiro Konno, Yoshiharu Hashimoto
1Laboratory of Anatomy, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060-0818, Japan.
Abstract:
The aim of this study was to clarify the role of the renal renin-angiotensin system (RAS) in diabetic nephropathy (DN), which was induced by injection of streptozotocin (STZ). Male CBA/N and CBA/J mice were compared in this study. The former possesses a single renin gene, Ren1, whereas the latter carries two renin genes, Ren1 and Ren2. To examine the molecular dynamics of renal RAS, including renin, angiotensinogen (Agt), angiotensin-converting enzyme (Ace), angiotensin type 1 (Agtr1) and type 2 (Agtr2) receptors in experimental DN, we performed laser-microdissection (LMD) followed by reverse transcriptase nested polymerase chain reaction using each specific primer pairs and immunohistochemistry for renin and angiotensin II. CBA/N mice had a higher response after injection of STZ than CBA/J mice, showing a significant increase of the kidney/body weight ratio, although there was no significant difference between the two strains for the blood glucose level or pancreatic beta-cell response. The onset of renal pathological changes associated with DN was earlier and more severe in CBA/N mice than in CBA/J mice. Distinct immunoreactivities for renin and angiotensin II were newly distributed on the flattened epithelial cells in the dilated distal tubules in the cortex as well as the collecting ducts in the cortex and medulla, and were demonstrated more intensely in CBA/N mice than in CBA/J mice. Microdissectional analysis in both DN models revealed a higher incidence of RAS-related gene expression in CBA/J, Ren 1 Ren 2 mice than in CBA/N, Ren 1 mice. These findings suggest that intrarenal RAS plays an important role in the onset of renal pathological changes associated with DN. Additionally, Ren 1 mice have more severe histopathological nephropathy than Ren1 Ren2 mice, followed by marked production of angiotensin II.
Insights
Diabetic nephropathy (DN) severity in mice depends on renin gene copy number. Mice with one renin gene (Ren1) showed more severe DN and angiotensin II production than those with two (Ren1 and Ren2).
Area of Science:
- Nephrology
- Endocrinology
- Molecular Biology
Background:
- Diabetic nephropathy (DN) is a major complication of diabetes, characterized by progressive kidney damage.
- The renal renin-angiotensin system (RAS) is implicated in DN pathogenesis, but its precise role, especially concerning renin gene variations, remains unclear.
Purpose of the Study:
- To investigate the role of the intrarenal RAS in streptozotocin (STZ)-induced diabetic nephropathy (DN) using mouse models with different renin gene copy numbers.
- To compare the molecular dynamics and pathological changes of the renal RAS in CBA/N (Ren1) and CBA/J (Ren1 and Ren2) mice during experimental DN.
Main Methods:
- Induction of DN in male CBA/N (single renin gene, Ren1) and CBA/J (two renin genes, Ren1 and Ren2) mice using streptozotocin (STZ).
- Assessment of kidney/body weight ratio, blood glucose, and pancreatic beta-cell response.
- Laser-microdissection (LMD) coupled with RT-nested PCR to analyze gene expression of RAS components (renin, Agt, Ace, Agtr1, Agtr2).
- Immunohistochemistry to evaluate the distribution and intensity of renin and angiotensin II.
Main Results:
- CBA/N mice exhibited a more pronounced increase in kidney/body weight ratio after STZ injection compared to CBA/J mice, indicating greater renal response.
- Renal pathological changes associated with DN onset were earlier and more severe in CBA/N mice than in CBA/J mice.
- Distinct and intense immunoreactivity for renin and angiotensin II was observed in dilated tubules and collecting ducts of CBA/N mice.
- Microdissectional analysis revealed higher expression of RAS-related genes in CBA/J (Ren1 Ren2) mice compared to CBA/N (Ren1) mice.
Conclusions:
- Intrarenal RAS plays a significant role in the development of renal pathological changes in DN.
- Mice with a single renin gene (Ren1) experience more severe histopathological nephropathy and angiotensin II production in DN compared to mice with two renin genes (Ren1 Ren2).
- The number of renin genes influences the severity of DN and the intrarenal RAS activity.
