Fig. 3.

Downregulation of endocytic machinery components is a common trait of gliomas with different grades and subclasses.

(a) Immunoblot analysis of selected endocytic machinery components. Full names of proteins can be found in Table S4. To detect AP-2, we used an antibody specifically recognizing the brain-specific αA-subunit of AP-2. Asterisks indicate unspecific cross-reacting proteins. (b) Altered steady-state distribution of TfR between primary cells derived from BTB251 and BTB152 with mild and strong reduction of endocytic machinery, respectively. Accumulation of TfR at the cell surface in BTB152 is quantitated in percent relative to BTB251 (mean and standard deviation of four independent experiments). BTB-derived primary cells also displayed a reduction in endocytic machinery components (Dyn 1/2, AP-2 α, CHC17, EndoA1). (c) Altered steady-state distribution of EGFR. Normalized EGFR surface fraction is quantitated as in (b) (mean and standard deviation of four independent experiments). (d) Key endocytic machinery components (Dyn1/2, AP-2α, CHC17, EndoA1) are downregulated in various glioma subtypes, GB (classical), GB (mesenchymal), GB (PN), astrocytoma and oligodendroglioma. GB (classical), GB (mesenchymal), GB (PN) have been selected based on methylomic classifiers [12]; astrocytoma have been selected based on the IDH1/2 mutation status and absence of 1p19q codel; oligodendroglioma have been selected based on IDH1/2 mutation status and 1p19q codel [1]. Protein levels were quantified and plotted below in percent of the control sample of white matter mean and standard deviation of n = 8 GB (IDHwt, mesenchymal), n = 8 GB (IDHwt, classical), n = 11 astrocytoma (IDHmut), and n = 6 oligodendroglioma (IDHmut + 1p19q codel).