Figure 3. Mitochondrial import of SLIRP is upregulated during antiviral response.

(A) The expression of SLIRP in free cytosol, membrane organelle, and nucleus upon poly I:C transfection. The following proteins are used to confirm successful subcellular fractionation: JNK for the free cytosol, RAB5 for the membrane, and Lamin A/C for the nucleus. (B) Representative fluorescence images of SLIRP and mitochondria upon poly I:C transfection. Scale bar, 25 μm. Quantified signal intensities averaged over 17 images are presented below. (C) Interaction between SLIRP and mtRNAs upon poly I:C transfection was examined by SLIRP fCLIP followed by RT-qPCR analysis (n=4). (D) Analysis of mtRNA stability before and after poly I:C transfection in control and SLIRP-deficient cells. (E) Analysis of the RNA expression of genes involved in the TOM complex upon poly I:C stimulation. (F) Heatmap showing the degree of mtRNA induction by poly I:C after downregulating the indicated target genes involved in the TOM complex. (G) Western blot analysis for SLIRP expression upon poly I:C in the cytosol and membrane fraction, with or without TOMM40. JNK is used as a marker for the cytosol fraction while AIF is used as a marker for the membrane fraction. Unless mentioned, three independent experiments were carried out, and error bars denote s.e.m. All of the statistical significances were calculated using one-tail Student’s t-tests; * p ≤ 0.05, ** p ≤ 0.01, and *** p ≤ 0.001.