Figure 6. Deletion of integrin β₁ in renin lineage cells inhibits arteriolar hypertrophy in Ren1^c-KO mice.

(A) Violin plots and ISH for Itgb1 mRNA in Renin^null cells. Scale bars: 50 μm. (B) Immunofluorescence staining for α-SMA and integrin β1 in kidneys from Ren1^c-KO control and Ren1^c-KO with Itgb1-cKO mice. Arrows indicate the α-SMA–positive cells at the JG area. Integrin β₁ was not observed at the JG area of the Ren1^c-KO Itgb1-cKO mice. Scale bars: 20 μm. (C and D) Arteriolar hypertrophy was prevented in Ren1^c-KO Itgb1-cKO mice. Immunohistochemistry for α-SMA showed decreased thickness of the walls of afferent arterioles in Ren1^c-KO Itgb1-cKO mice compared with Ren1^c-KO control (C). Scale bars: 50 μm. The mean wall thickness of afferent arterioles at the JG area was significantly smaller in Ren1^c-KO Itgb1-cKO mice (n = 6, Student’s t test) (D). Relative frequency distribution histograms show that the distribution curve corresponding to the Ren1^c-KO Itgb1-cKO mice is displaced to the left of the control mice (D). (E) ISH for Akr1b7 mRNA in kidneys from Ren1^c-KO Itgb1-c-KO and Ren1^c-KO control mice. The number of Akr1b7 mRNA-positive cells in Ren1^c-KO Itgb1-cKO mice is much smaller than in Ren1^c-KO controls. Arrows indicate afferent arterioles. Scale bars: 50 μm. (F) GFP showed in the walls of hypertrophic afferent arterioles in the Ren1^c-KO control (Ren1^c-KO^–/– Ren1^cCre/+ Itgb1^fl/+ R26mTmG) but was absent in the arterioles of Ren1^c-KO Itgb1-cKO kidneys (Ren1^c-KO^–/– Ren1^cCre/+ Itgb1^fl/fl R26mTmG) while persisting in some tubules. Scale bars: 50 μm. (G) PAS staining and Masson’s trichrome staining in kidneys from Ren1^c-KO and Ren1^c-KO Itgb1-cKO mice showed fibrosis in both groups. Scale bars: 50 μm. All data are reported as means ± standard deviation. Black triangles represent male samples and purple dots female samples. ****P < 0.0001. Itgb1-cKO, deletion of the Itgb1 gene in cells of the renin lineage; JG, juxtaglomerular; PAS, periodic acid–Schiff; Ren1^c-KO, Ren1^c gene knockout.