Figure 8. PTN–PTPRZ1 signalling activates the Fyn–AKT pathway in GSCs.

(a,b) Hierarchical clustering analysis (a) and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis (b) of differentially expressed genes between the PTPRZ1-silencing GSCs and control GSCs (fold change ≥2.0). Cluster analyses were performed and visualized using the Cluster/Java Treeview. Pathway enrichment significance is presented as a P value with log2 transformation, Fisher's exact test and χ²-test. (c) Immunoblot analyses of phospho-AKT (p-Ser473) and total AKT in GSCs (T387 and T0912), showing that rhPTN stimulation markedly increases AKT-activating phosphorylation, while the anti-PTPRZ1 antibody treatment compromises rhPTN-stimulated AKT activation in GSCs. Cells were pretreated with anti-PTPRZ1 antibody or control IgG for 1 h followed by rhPTN treatment for 20 min. (d) Co-immunoprecipitation of PTPRZ1 with the Fyn-specific antibody from T387 and T0912 GSC cell lysates. Precipitation with normal rabbit IgG was used as a negative control. PTPRZ1 binds to Fyn in GSCs. (e) Immunoblot analyses of p-SFK (Tyr416) and Fyn in T387 GSCs, showing that rhPTN stimulation markedly increases activating phosphorylation of SFK (p-Tyr416), while the anti-PTPRZ1 antibody treatment largely abrogates SFK activation in GSCs. (f) Co-immunoprecipitation of p-SFK (p-Tyr416) with the Fyn-specific antibody in T387 GSCs. Phosphorylated Fyn, as represented by immunoprecipitated p-SFK with Fyn antibody, was increased after rhPTN exposure, and was compromised by anti-PTPRZ1 antibody. Precipitation with rabbit IgG was used as a negative control.