Journal: The Journal of Biological Chemistry
Article Title: A high-throughput screen for nucleolar function reveals a role for the signaling protein, SPRR3, in ribosome biogenesis
doi: 10.1016/j.jbc.2026.111132
Figure Lengend Snippet: siSPRR3 depletion results in a reduction in the number of nucleoli per nucleus in MCF10A cells. A , siSPRR3 depletion with siGENOME siRNAs reduces the number of nucleoli per nucleus. Images and histograms from a genome-wide screen using Dharmacon/Horizon siGENOME siRNAs . The images show nuclei (Hoechst, blue ) and nucleoli (anti-fibrillarin, red ) after 72 h of treatment with the negative control (siGFP), positive control (siUTP4), or siSPRR3 siRNAs. Histograms show the distribution of cells that have the indicated number of nucleoli per nucleus. Light grey shows the distribution for the negative control, black shows the test condition, and dark grey shows overlap of the two frequencies. B , siSPRR3 depletion with siON-TARGET (siONT) SMARTPool siRNA reduces the number of nucleoli per nucleus. The images show nuclei and nucleoli after 72 h of treatment with the negative control (non-targeting siRNA, siNT), positive control (siUTP4), or siSPRR3 siRNAs. The shading in the histograms is as in A ). The data were collected across four replicates which are pooled in the histogram. C , siSPRR3 depletion with individual siONT SMARTPool siRNAs (deconvolution) reduces the number of nucleoli per nucleus. The images show nuclei and nucleoli after 72 h of treatment with the negative control (siNT), positive control (siNOL11), or representative siSPRR3 individual siRNAs (SPRR3-si1 and SPRR3-si2). The shading in the histograms is as in ( A ). The histograms include all three replicates pooled. The table summarizes each of four individual siONT SMARTPool siRNAs, showing that a reduction in nucleolar number correlates with a loss in cell viability. D , siSPRR3 (custom subpool of SPRR3-si1 and SPRR3-si2) reduces SPRR3 mRNA levels in MCF10A cells. RT-qPCR data of SPRR3 mRNA demonstrating knockdown after 72 h. The data were normalized to 7SL RNA abundance, then to siNT for comparison using the ΔΔC T method. The mean ± SEM are shown alongside individual data points, colored by replicate. E , siSPRR3 (custom subpool of SPRR3-si1 and SPRR3-si2) reduces SPRR3 protein levels in MCF10A cells. Western blot of SPRR3 protein demonstrating decreased levels after 72 h. Protein levels were normalized to total protein (trichloroethanol total protein stain), then to siNT. The mean ± SEM are shown alongside individual data points, colored by replicate. This sample was run on the same Western blot as in . After imaging total protein on the membrane, the blot was cut between 10 to 15 kD markers to stain separately for SPRR3 ( E , above) or RPS28 . Data in ( D and E ) were analyzed by unpaired two-sided Welch's t -tests in GraphPad Prism. ∗, p < 0.05; ∗∗∗, p < 0.001.
Article Snippet: Human MCF10A breast epithelial cells (#CRL-10317, American Type Culture Collection) were cultured in DMEM/nutrient mixture F-12 (Gibco 11330032) with 5% horse serum (Gibco 16050122), 20 ng/ml epidermal growth factor (Peprotech AF1005), 0.5 μg/ml hydrocortisone (MilliporeSigma H0135), 100 ng/ml cholera toxin (MilliporeSigma C8052), and 10 μg/ml insulin (MilliporeSigma I1882).
Techniques: Genome Wide, Negative Control, Positive Control, Quantitative RT-PCR, Knockdown, Comparison, Western Blot, Staining, Imaging, Membrane