Journal: Molecular cancer research : MCR
Article Title: PCSK5 M452I is a recessive hypomorph exclusive to MCF10DCIS.com cells
doi: 10.1158/1541-7786.MCR-25-0211
Figure Lengend Snippet: Inducible reconstitution of PCSK5 alleles in PCSK5 −/− MCF10DCIS.com cells. A, Approach to MCF10DCIS.com engineering. Cells were transduced with a destabilizing domain (DD)-containing Cas9-P2A-Venus ( 61 ) and a single-guide RNA targeting Exon 4 of PCSK5 (sgPCSK5). Transduced cells were treated with 200 nM Shield-1 ( 61 ) to stabilize Cas9-P2A-Venus and 2% matrigel to promote PCSK5 accessibility before sorting single Venus-positive cells into 10 ng/ml GDF11 (to aid recovery upon PCSK5 loss) and screening genomic DNA (gDNA) of expanded clones for knockout. One confirmed PCSK5 −/− clone was then transduced with sgPCSK5-resistant, tetracycline (tet)-regulated, V5-tagged alleles of PCSK5 and selected polyclonally for hygromycin resistance. B, Sequence-confirmed knockout alleles of MCF10DCIS.com clone 3D8. The PCSK5 coding sequence (CDS) is shown with annotations for the signal peptide (SP, purple), proprotein sequence (Pro, green), and peptidase domain (blue) including its catalytic triad (yellow stars). The protospacer adjacent motif (PAM) of sgPCSK5 is just upstream of the first triad amino acid, and deletions (white, Allele 1) or insertions (pink, Allele 2) induce frameshift mutations (gray) removing the first amino acid in the catalytic triad (black outlined stars) and producing premature stop codons (red). C, Quantification of reconstituted PCSK5 alleles by calibrating against recombinant V5-containing Multitag protein at the indicated copies per cell ( 63 , 72 ). Cells were treated with 1 μg/ml doxycycline for 24 hours, and total protein from counted cells was immunoblotted by two-color fluorescence detection for V5 (800 channel) with tubulin and p38 (700 channel) used as loading controls for cells. Copy number estimates are: PCSK5 WT , 136,000 ± 11,000 copies per cell; PCSK5 M452I , 164,000 ± 6,000 copies per cell; PCSK5 T288P , 176,000 ± 15,000 copies per cell ( N = 4 biological replicates).
Article Snippet: Concentrated samples were stored at −80°C, volumed up to 205 μl with Reagent Diluent (R&D Systems, DY008B) after thawing, and measured with the GDF11 ELISA (R&D Systems, DY1958) after adding two extended serial dilutions of recombinant GDF11 (15.5 pg/ml and 7.75 pg/ml).
Techniques: Transduction, Clone Assay, Knock-Out, Sequencing, Recombinant, Fluorescence