Fig. 1.

High NaCl causes movement of Mre11 into the cytoplasm of primary renal cells where it exists in 2 pools: a soluble fraction distributed throughout cytoplasm and a second fraction within organelles. A: Western blot analysis of Mre11 translocation from nucleus to cytoplasm after treatment for 2 h, either increasing NaCl (final osmolality 500 mosmol/kg) or exchanging to medium at 300 mosmol/kg. Top: representative Western blot; bottom: % of total Mre11 in cytoplasmic fraction, calculated based on densitometry, volumes of nuclear and cytoplasmic protein fractions, and volumes loaded on the gel (means ± SE, n = 4, *P < 0.05) (See materials and methods for the calculation). B: analysis by immunocytochemistry and in situ cell fractionation of the subcellular localization of Mre11. Cells were exposed for 2 h to high NaCl (final osmolality 500 mosmol/kg) or kept at 300 mosmol/kg, fixed with 2% formaldehyde, and then treated with 0.1% or 1% of Triton X-100 in PBS for 10 min. Top: 0.1% Triton X-100 permeabilizes plasma membranes; bottom: 1% Triton X-100 extracts soluble cytoplasmic proteins.