Fig. 5: Corisin penetrates kidney cells via the human albumin receptor cubilin to target mitochondria.

A–D, Human Caki-2 cell lines and normal human primary podocytes were cultured to near confluence, then treated with fluorescein isothiocyanate (FITC)-labeled corisin (corisin-FITC) or FITC-labeled scrambled peptide for 4 h. MitoTracker was added 30 min before fixation to label mitochondria, and cells were subsequently imaged via microscopy. The fluorescence intensities of F-actin and DAPI were quantified using ImageJ. Scale bars represent 20 µm. n = 8 replicates. Data are presented as mean ± SD. Statistical analysis was conducted using a two-sided unpaired t-test. E–G, Normal human primary podocytes were cultured for 48 h with siRNA targeting CD36, megalin, cubilin, SPARC, and FCGRT, and the relative expression of albumin receptors was evaluated. n = 4 replicates. Data are expressed as the mean ± SD. Statistical comparison between each receptor-specific siRNA and its corresponding control siRNA was performed using a two-sided unpaired t-test. In a separate experiment, cells were cultured under the same conditions and then treated with corisin-FITC, MitoTracker, and DAPI and observed using fluorescence microscopy. The fluorescence intensities of F-actin and DAPI were quantified using ImageJ, an open-source software from the National Institutes of Health (NIH). Scale bars represent 20 µm. n = 8 replicates. n = 12 in control and n = 6 in remaining groups. Data are presented as mean ± SD. Statistical analysis was conducted using ANOVA followed by Dunnett’s test; all tests were two-sided. The source data are available in the Source Data file.