Fig. 8: Phafin2 is required for amino acid scavenging by cancer cells. | Nature Communications

Fig. 8: Phafin2 is required for amino acid scavenging by cancer cells.

From: The phosphoinositide coincidence detector Phafin2 promotes macropinocytosis by coordinating actin organisation at forming macropinosomes

Fig. 8

Localization of Phafin2 in MIA-PACA2 cells. a Phafin2-GFP labels large vacuoles and shows biphasic localization to macropinosomes in MIA-PACA2 cells. Representative images from 10 cells. Scale bar: 10 µm. b Flow cytometry measurement of DQ-BSA by MIA-PACA2 cells. Deletion of Phafin2 strongly reduces BSA uptake. n = 3 experiments, mean + 95% CI, ANOVA with Tukey’s post-test, p = 0.0002. c MIA-PACA2 cells lacking Phafin2 are unable to scavenge extracellular nutrients. WT cells can scavenge extracellular proteins under amino acid limiting conditions. KO cells are unable to utilize extracellular proteins. n = 6 experiments, shown are mean + 95% CI, ANOVA with Tukey’s post-test, p = 0.0001. d Phafin2 is frequently amplified in cancer samples. A screen of the cBioportal cancer database shows frequent amplification of Phafin2 in cancer samples, whereas deletions or mutations are rare. e Phafin2 and the related protein Phafin1 are the only frequently amplified FYVE domain proteins. Shown is the frequency of amplification of 31 FYVE proteins in the curated dataset of non-redundant studies in the cBioPortal (representing 48834 non-redundant samples). Mean + /− 95% CI. f Model of Phafin2 function on forming macropinosomes. Phafin2 binds to newly formed macropinosomes by coincidence sensing of PtdIns3P and PtdIns4P. By binding to filamentous actin, Phafin2 links the macropinosome membrane to the actin cytoskeleton. Turnover of phosphoinositides leads to a dissociation of Phafin2 from the macropinosome. Statistics source data for b, c, e are provided in this paper.

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