Fig. 5

Cathepsin maturation is selectively impaired in Grn^−/− microglia. a Schematic representation of the brain cell isolation using MACS Technology (Miltenyi Biotec) b PGRN expression in acutely isolated microglia, astrocytes and neurons enriched fractions of 4- month-old wt mice detected by immunoblotting. The identity of neural cell types was verified by detection of Iba1 for microglia, GFAP for astrocytes and Tuj1 for neurons. c-i Cathepsin expression and maturation in the CD11b-positive, microglia enriched, fraction and the CD11b-negative, microglia depleted cellular fraction isolated form cortices of brain from 3-month-old Grn^+/+ (wt) and Grn^−/− (ko) mice. Representative immunoblots for the cathepsin expression of CatD (c, d), CatB (e, f), CatL (g, h) and for CatS (i) (only microglia enriched fraction). The molecular weight standards in kilo Daltons (kDa) are indicated on the left side of all immunoblots. A dotted line in the blot indicates that samples of heterozygous mice were cut out, but all samples were loaded on one gel. Quantification of immunoblots for total cathepsin or maturation variants pro-form (p), single chain (sc) and heavy chain (hc) normalized to wt are shown as mean ± SD. For statistical analysis the unpaired, two-tailed student’s t-test was used to compare ko to wt mice (n = 3–5) (*, p < 0.05; **, p < 0.01; ***, p < 0.001; ns, not significant) (c-i)