Cytoplasmic retention of the DNA/RNA-binding protein FUS ameliorates organ fibrosis in mice
Manuel Chiusa, … , Roy Zent, Ambra Pozzi
Manuel Chiusa, … , Roy Zent, Ambra Pozzi
Published March 15, 2024
Citation Information: J Clin Invest. 2024;134(6):e175158. https://doi.org/10.1172/JCI175158.
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Research Article Hepatology Nephrology

Cytoplasmic retention of the DNA/RNA-binding protein FUS ameliorates organ fibrosis in mice

Abstract

Uncontrolled accumulation of extracellular matrix leads to tissue fibrosis and loss of organ function. We previously demonstrated in vitro that the DNA/RNA-binding protein fused in sarcoma (FUS) promotes fibrotic responses by translocating to the nucleus, where it initiates collagen gene transcription. However, it is still not known whether FUS is profibrotic in vivo and whether preventing its nuclear translocation might inhibit development of fibrosis following injury. We now demonstrate that levels of nuclear FUS are significantly increased in mouse models of kidney and liver fibrosis. To evaluate the direct role of FUS nuclear translocation in fibrosis, we used mice that carry a mutation in the FUS nuclear localization sequence (FUSR521G) and the cell-penetrating peptide CP-FUS-NLS that we previously showed inhibits FUS nuclear translocation in vitro. We provide evidence that FUSR521G mice or CP-FUS-NLS–treated mice showed reduced nuclear FUS and fibrosis following injury. Finally, differential gene expression analysis and immunohistochemistry of tissues from individuals with focal segmental glomerulosclerosis or nonalcoholic steatohepatitis revealed significant upregulation of FUS and/or collagen genes and FUS protein nuclear localization in diseased organs. These results demonstrate that injury-induced nuclear translocation of FUS contributes to fibrosis and highlight CP-FUS-NLS as a promising therapeutic option for organ fibrosis.

Authors

Manuel Chiusa, Youngmin A. Lee, Ming-Zhi Zhang, Raymond C. Harris, Taylor Sherrill, Volkhard Lindner, Craig R. Brooks, Gang Yu, Agnes B. Fogo, Charles R. Flynn, Jozef Zienkiewicz, Jacek Hawiger, Roy Zent, Ambra Pozzi

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Figure 7

Pharmacologic inhibition of FUS nuclear translocation ameliorates CCl4-induced liver fibrosis.

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Pharmacologic inhibition of FUS nuclear translocation ameliorates CCl4-i...
(A) Representative images of liver sections from WT mice treated with CCl4 for 6 weeks stained for desmin (green), FUS (red), and DAPI (blue). CV, central vein. Arrowheads indicate desmin-positive cells. Scale bars: 20 μm. (B) Nuclear FUS intensity per microscopic field was calculated using ImageJ. Values are the mean ± SD, and symbols represent individual livers (n = 3 vehicle, n = 4 CCl4, with an average of at least 120 cells per microscopic field per liver). (C and D) Liver/body weight and spleen/body weight ratios in uninjured (vehicle) mice and mice treated for 6 weeks with CCl4 alone or in combination with CP-mut-FUS-NLS or CP-FUS-NLS. Values are the mean ± SD, and symbols represent individual livers or spleens (n = 5 vehicle, n = 10 CCl4, n = 10 CCl4+CP-mutFUS-NLS, n = 10 CCl4+CP-FUS-NLS). (E) Reconstruction of histologic images of median and right lobes of livers from the mice described in C stained with Picrosirius red staining. Scale bars: 1 mm. (F) Representative images of Picrosirius red–stained liver median and right lobes. Scale bars: 30 μm. (G) The amount of fibrillar collagen was evaluated using ImageJ software as described in Methods. Values are the mean ± SD, and symbols represent individual livers (n = 5 vehicle, n = 10 CCl4, n = 10 CCl4+CP-mutFUS-NLS, n = 10 CCl4+CP-FUS-NLS, with an average of at least 5 microscopic fields per lobe). Statistical analysis: unpaired 2-tailed t test (B); 1-way ANOVA followed by Dunnett’s multiple-comparison test (C, D, and G).