FIGURE 4.

Lack of XT2 in coll^−/y but not in ace2^−/y mouse kidney. A, immunofluorescence of wild-type kidney co-labeled with XT2 and ACE2 and on a consecutive section co-labeled with Coll and actin. G, glomerulus. B, real time reverse transcription-PCR of XT2 and Coll on ace2^+/y and ace2^−/y total kidney RNA. Bars, mean value ± S.E.; n = 3 mice per genotype. C and D, kidney brush border membrane vesicles (BBMV) (20 μg) from coll^+/y and coll^−/y mice (C) and ace2^+/y and ace2^−/y mice (D) were analyzed by Western blot using antibodies against XT2, Coll (with a specific signal at 42 kDa; see supplemental material), ACE2, and β-actin (βa). Each lane corresponds to material prepared from one mouse. E and F, immunofluorescence of coll^−/y kidney co-labeled with XT2 and ACE2 (E) and ace2^−/y kidney labeled with XT2 and on a consecutive section with Coll (F). Immunofluorescence experiments were performed at least three times with similar results for each antibody. Representative images are shown. As shown also by Western blot in C and D, XT2 expression is lacking in kidney of coll null mice, whereas it is expressed in ace2 null mice.