mTORC2 interactome and localization determine aggressiveness of high-grade glioma cells through association with gelsolin

Chantaravisoot et al., Scientific Reports, 2023, asked why glioblastoma cells move so much better than low grade glioma cells, and answered it by mapping everything the mTORC2 complex touches. Affinity purification mass spectrometry of RICTOR immunoprecipitates, run across activated, starved and drug inhibited cells and across a high grade and a low grade line, kept returning one protein as the largest difference: gelsolin, an actin severing and capping protein.

Testing that required removing gelsolin without removing anything else, and for the imaging and proteomic arms the group used an AUMsilence sdASO against GSN from AUM BioTech, with a matched scrambled control, at 1.0 and 10.0 μM for 48 hours on U87MG glioblastoma cells. The Methods name a lipid transfection reagent for the small interfering RNA against RICTOR and for the small interfering RNA used in the migration assays, and name none for this oligo. Without gelsolin, RICTOR came off the plasma membrane and sat in the cytoplasm and nuclei instead, and the actin network was most disrupted at the higher of the two doses.

The proteomic readout is the part that shows what a clean knockdown buys. Gelsolin was depleted from the pulled down complex by more than fourfold, and the four core components of mTORC2 stayed intact while the actin-binding proteins around them fell away. That pattern is what let the authors place gelsolin as the connector between the complex and the machinery that builds the protrusions a migrating cell needs. One boundary belongs on any use of this paper: the wound healing migration assays in it used a small interfering RNA from another supplier delivered with a transfection reagent, not the AUM oligo.