Fig. 1

Cytosolic FUS is increased in the interstitial fibroblasts of IPF patients. a Analysis of FUS mRNA via qRT‒PCR in fibroblasts derived from healthy (HD) or IPF lungs (n = 5 HD, n = 5 IPF). The values were normalized to those of the housekeeping gene β-actin (ACTB). The mean FUS mRNA expression in HD fibroblasts was set as one. b Immunoblot analysis of FUS or β-actin in total lysates of fibroblasts derived from the lungs of HD or IPF patients. Quantification was performed after normalizing the integrated density values (IDVs) of FUS to those of β-actin. Blots and analyses of fibroblasts from n = 6 HDs and n = 6 IPF patients. c Immunofluorescence analysis of FUS (red) and the fibroblast marker α-smooth muscle actin (α-SMA, green) in cultured fibroblasts from HD and IPF patient lungs. DAPI was used for nuclear staining. Scale bar = 100 µm. d Nuclear and cytosolic fractions were enriched from the fibroblasts of HD and IPF lungs, and western blotting was performed for FUS, N-Lamin (nuclear marker), or β-actin (cytosol marker). The right side shows quantification after normalization of the IDV of FUS vs. N-Lamin or FUS vs. β-actin. Fractionation was performed from fibroblasts of n = 4 HDs and n = 4 IPF. P-value summary from (a–d): *P < 0.05, ***P < 0.001, ns = not significant. e Transmission electron microscopy of immunogold-labeled samples. Top: HD cells are labeled predominantly in the nucleus. Bottom: IPF cells show increased labeling in the cytoplasm compared with HD cells. N: Nucleus; C: Cytoplasm