Figure 4.

Pseudotime analysis shows dynamic states of INS expression and stress recovery. (A) An UPR score was calculated using a gene set obtained from IPA Ingenuity. Briefly, the score is the average of scaled UMI of all genes in the gene set. The distribution of the score was calculated by random selection of the genes for the specific gene set with 1,000 iterations. The empirical P value was calculated against the distribution of the score. The score value of each cell was plotted into pseudotime ordering. (B) INS expression pattern is shown in pseudotime ordering. Each dot represents a cell and the color highlights the level of composite score or gene expression. (C) Pseudotime trajectory where each dot represents a cell and the grayscale color highlights the trajectory ranging from 0 to 8.9 [21]. (D) Human β-cells undergoing active insulin biosynthesis and secretion (INS^hiUPR^lo) are likely to become stressed, transitioning to a period of recovery encompassing UPR activation and low INS expression (INS^loUPR^hi). Following recovery, β-cells transition to a state characterized by low INS expression and reduced UPR activation (INS^loUPR^lo), where they are nearly ready to become actively secreting again. Among these states, proliferating β-cells were primarily found in the state of low INS expression and high UPR activation. Adapted from Ref. Xin et al. [21].