Assays

All samples were reconstituted in 0.1% formic acid and separated using an Easy-nLC1200 liquid chromatograph (Thermo Scientific) followed by peptide detection on a Q Exactive HF mass spectrometer (Thermo Scientific). Samples were separated on a 75 µm x 15 cm custom-made fused silica capillary packed with C18AQ resin (Reprosil-PUR 120, 1.9 µm, Dr. Maisch), flow rates and gradients were adjusted according to the experiment. Except for plasma membranome analysis, peptide mixtures were separated on a ...

Proximity labeling: Cells were supplemented with 500 µM biotin-phenol (IrisBiotech) for 30 min at 37°C before addition of 1 mM H2O2 at room temperature. Cells were then first washed with quencher solution (1 mM sodium azide, 10 mM sodium ascorbate and 5 mM Trolox in DPBS), then with DPBS, scraped and harvested. Proteinase K digest: All steps were carried out at 4°C unless stated otherwise. Cells were washed and suspended in homogenization buffer I (10 mM KCl, 1.5 mM MgCl2, 10 mM HEPES-KOH and 1 ...

pAstros were transduced with control or Ngn2-expressing retrovirus. 2DPT, media was replaced with differentiation media in absence of presence of AMG; 20DPT, DsRed-positive cells were sorted, barcoded with CMOs and analyzed by scRNAseq via 10XGenoics platform

pAstros were transduced with control or Ngn2-expressing retrovirus. 2DPT, media was replaced with differentiation media in absence of presence of AMG; 5DPT, DsRed-positive cells were sorted, barcoded with CMOs and analyzed by scRNAseq via 10XGenoics platform

Cells were harvested and centrifuged 400g for 10 min at 4°C. Cell pellets were resuspended in STE-Buffer (250mM sucrose, 5mM Tris pH 7, 1mM EGTA, PI mix 1:500) and lysed with a 27-gauge needle. Samples were centrifuged 10 min at 800g to remove nuclei, then 10 min at 15.000g to remove mitochondria and finally 1 hour 100.000g. The resulting pellets were washed twice with 100mM Na2CO3 and centrifuged 30 min at 100000g after each wash. Pellets from membrane preparations were dissolved in lysis buffer ...

Nine patients per group were treated with either acitretin or vehicle control. Cerebrospinal fluid was collected before (baseline value) and after treatment. A volume of 5 µL of CSF per sample was subjected to proteolytic digestion in 50 mM ammonium bicarbonate with 0.1% sodium deoxycholate (Sigma Aldrich, Germany) as previously described (Pigoni et al., 2016). Briefly, protein disulfide bonds were reduced with dithiothreitol and sulfhydryl residues were alkylated using iodoacetamide. Proteins ...

2 x 108 wild-type or Tspan15-knockout HEK-293T cells were lysed in 1% digitonin lysis buffer containing protease inhibitor cocktail (Sigma-Aldrich). Lysates were pre-cleared with protein G sepharose prior to immunoprecipitation with Tspan15 mAb 1C12 chemically cross-linked to protein G sepharose with dimethyl pimelimidate (Thermo Fisher Scientific). Five independent immunoprecipitations were carried out for each cell type. Immunoprecipitation samples in non-reducing Laemmli buffer were subjected ...