Journal: bioRxiv
Article Title: C-terminus CD28 phosphorylation (Y218) modulates IL-2 secretion and antitumor effect of CAR-T cells
doi: 10.64898/2026.01.28.701378
Figure Lengend Snippet: A . Schematic representation of WT and PYRP mutant CAR constructs. In the PYRP mutant, alanine (A) 217 and serine (S) 220 were substituted with prolines (P) to generate a proline-rich domain. B . PSCA-targeted WT and PYRP CAR-T cells were cocultured with HPAC WT cells for 0, 1, 10, 30, or 60 min. CAR molecules were immunoprecipitated using protein-L coated beads and co-immunoprecipitated proteins were analyzed by Western blot. Upper panel: Representative Western blot results showing ITK present in CAR immunoprecipitate. CD3ζ staining of the CAR molecule was used as a bait control. Lower panel: Intensity of ITK with respect a total CAR (CD3ζ) was analyzed by densitometry (representative plot). C. PSCA WT and PYRP CAR-T cells were stimulated with HPAC WT cells for 10 min and phosphorylation of Y218 was analyzed by mass spectrometry. Bar charts represent the intensity of phosphorylated Y218 normalized to the total CAR signal. Significance was determined by one-way Anova. * = P<0.05. Data is represented as the mean ± standard deviation (SD). D and F. PSCA WT and PYRP CAR-T cells were cocultured with HPAC WT cells. Supernatant was collected after 24 hours and cytokine production was measured by ELISA. Significance was determined by one-way ANOVA. * = P<0.05, ** = P<0.01. Each symbol represents an independent experiment from 3 different healthy donors. Data is represented as the mean ± standard deviation (SD). E. PSCA WT and PYRP CAR-T cells were cocultured with HPAC WT cells. RNA was extracted after 24 hours and IL-2 mRNA production was evaluated using quantitative Time PCR. CAR mRNA was used as normalization control. Significance was determined by one-way Anova. ** = P<0.01, *** = P<0.001. Each symbol represents an independent experiment from 3 different healthy donors. Data is represented as the mean ± standard deviation (SD). G. % of change in tumor volume (compared to baseline) is represented (n=5). Representative example of two independent experiments. Significance was determined by permutation two sample t-test. * = P<0.05.
Article Snippet: Primary antibodies: rabbit anti-CD28 pY218 (Abcam, ab138404), anti-CD28, rabbit ant-ZAP70 pY319 (Cell Signaling, #2717), rabbit anti-ZAP70 (Cell Signaling, #2705), rabbit anti-PLCγ pY783 (Abcam, ab76155), rabbit anti-PLCγ (Abcam, ab76155), rabbit anti-VAV1 pY174 (Abcam, ab76225), rabbit anti-VAV1 (Abcam, ab97574), rabbit anti-LCK (Abcam, ab32149), ITK (Cell Signaling, 77215), mouse anti-CD3ζ (Santa Cruz, sc-166275), mouse anti-B actin (Santa Cruz, sc-47778).
Techniques: Mutagenesis, Construct, Immunoprecipitation, Western Blot, Staining, Control, Phospho-proteomics, Mass Spectrometry, Standard Deviation, Enzyme-linked Immunosorbent Assay