Journal: Nature Cell Biology
Article Title: Spatial and functional separation of mTORC1 signalling in response to different amino acid sources
doi: 10.1038/s41556-024-01523-7
Figure Lengend Snippet: a , Immunoblots with lysates from HEK293FT WT and RagA/B KO cells, treated with media containing or lacking AAs, in basal (+AA), starvation (−AA) or add-back (–/+AA) conditions, probed with the indicated antibodies. For basal (+AA) conditions, culture media were replaced by +AA treatment media 90 min before lysis. For AA starvation (−AA), culture media were replaced by starvation media 1 h before lysis. For AA add-back samples (–/+AA), cells were first starved as described above and then starvation media were replaced by +AA treatment media for 30 min. The composition of all media is described in . b , In vitro kinase assays with mTORC1 immunopurified from WT or RagA/B KO HEK293FT cells and recombinant 4E-BP1 protein used as substrate, with 4E-BP1 phosphorylation detected by immunoblotting. No ATP samples (−ATP) used as negative controls. c , Lyso-IP experiments in WT and RagA/B KO HEK293FT cells stably expressing HA-tagged TMEM192 (or FLAG-TMEM192 as negative control). Intact lysosomes immunopurified by anti-HA IPs under native conditions, and the presence of the indicated proteins in the lysosomal and non-lysosomal fractions, as well as in whole-cell lysates, analysed by immunoblotting. Note the absence of S6K from lysosomal fractions and the presence of phospho-TFEB in the lysosomal fractions only of control cells. n = 2 independent experiments. d , e , Phosphorylation of multiple mTORC1 substrates is largely unaffected by BafA1 treatment (100 nM, 6 h) ( d ) or loss of Rag GTPases ( e ). In e , Torin1 (250 nM, 1 h) was used as a control for mTOR inhibition. f , g , GRASP55 phosphorylation by mTORC1 is retained in RagA/B KO ( f ) or BafA1-treated cells (100 nM, 6 h) ( g ), similarly to that of S6K. In g , starvation was performed as in a . Torin1 (250 nM, 1 h) was used as a control for mTOR inhibition. h , RagC is an additional lysosomal mTORC1 substrate that requires properly functioning lysosomes for its phosphorylation, similarly to TFEB/TFE3. AA starvation or blockage of lysosomal function with BafA1 (100 nM, 6 h) decrease RagC phosphorylation (shown as elevated RagC signal with #5466). Treatments performed as in a . i , j , Lysosomal localization of RagC is unaffected by BafA1 treatment (100 nM, 6 h) ( i ). Quantification of RagC/LAMP2 colocalization in ( j ). Scale bars, 25 μm and for insets, 5 μm. n = 50 individual cells from five independent fields per condition. Arrowheads indicate bands corresponding to different protein forms when multiple bands are present. P, phosphorylated form. Data in graphs shown as mean ± s.e.m. n.s., non-significant. Source numerical data and unprocessed blots are available in . See also Extended Data Figs. – .
Article Snippet: The H4B4 and ABL-93 antibodies against LAMP2 were obtained from the Developmental Studies Hybridoma Bank (DSHB), created by the National Institute of Child Health and Human Development (NICHD) of the National Institutes of Health (NIH) and maintained at The University of Iowa, Department of Biology.
Techniques: Western Blot, Lysis, In Vitro, Recombinant, Phospho-proteomics, Stable Transfection, Expressing, Negative Control, Control, Inhibition