Hyperosmotic Stress Induces a Specific Pattern for Stress Granule Formation in Human-Induced Pluripotent Stem Cells

Figure 4

Clustering and functional overrepresentation analysis of differential proteomic data. (a) Fuzzy c-means clustering identifies distinct patterns in protein levels upon NaCl treatment in hiPSCs/IMR90-1 and SH-SY5Y cells. Clustering into 5 clusters was performed to standardized changes in protein levels when compared to untreated cells (). Profile plots of the clusters indicate the following general states: 1 and 2, strongly increased expression in 400 mM in hiPSCs/IMR90-1; 3, moderate increase expression in 400 mM in hiPSCs/IMR90-1; and 4 and 5, decreased expressions in 400 mM in hiPSCs/IMR90-1. (b) Heatmap showing Gene Ontology (GO) terms which are statistically overrepresented within clusters as indicated by a high −log¹⁰ value. (c) Selected subtype markers across selected cluster 3 in hiPSCs/IMR90-1 and SH-SY5Y. Selected subtype markers exhibit the subtype-expected pattern (for each pairwise comparison, we used Student -test, ). Microtubule proteins, TBCA, TUBB, STMN1, TUBA1B, TUBB4B, PKBP4, DYNC1H1, MAPRE1, and DPYSL2 were significantly lower in hiPSCs/IMR90-1 under 400 mM of NaCl treatment. NT: no treatment; ns: not significant compared to NT; : adjusted value less than 0.05 compared to NT; : adjusted value less than 0.01 compared to NT.

(a)

(b)

(c)