Fig. 6: HAPSTR2 safeguards resilience.

a Plot illustrating relatively high expression of endogenous HAPSTR2 in H661 cells. b RNA-sequencing of HAPSTR paralog depletion in isolation or together using siRNA; all differentially expressed genes in the double knockdown condition are shown. See Supplementary Data 3. N = 3. c Magnitude of effects on gene expression for the indicated perturbation, where each point is a gene (n = 589) from cluster 1 or 2. Note that the fold change for genes in Cluster 2 is multiplied by -1 to include both up- and down-regulated genes. Mann–Whitney U, two-tailed. d The observed gene expression change after double paralog knockdown, relative to the expected effect if siHAPSTR1 and siHAPSTR2 were acting independently (and thus added together). L2FC: Log-2-fold change. 589 genes, one-sample t test. e HAPSTR1 knockout (KO) via CRISPR-Cas9 markedly reduces fitness in most cancer cell lines, but less so in cell lines expressing relatively high amounts of HAPSTR2. Note that the essentiality score here is a continuous measure, where 0 is no fitness effect and 1 is the average growth defect of targeting genes considered universally required for cell growth. N = 973 cell lines analyzed (group breakdown in figure). Mann–Whitney U, one-tailed. Box is median and lower/upper quartile with whiskers 150% of the interquartile range. f Stress tolerance, quantified as 6-day growth relative to wild-type (WT) cells, of H661 population knockout cells created via CRISPR-Cas9 sgRNAs targeting HAPSTR paralogs, AAVS1 (safe harbor control), and/or a non-targeting (NT) sgRNA. N = 5. Colch, colchicine; ATRi, ATR inhibitor AZD6738; NAEi, Neddylation inhibitor MLN4924; CPT, camptothecin. g Schematic model of two functions for HAPSTR2 (H2), augmenting HAPSTR1 (H1) stability normally and safeguarding against total loss of HAPSTR functionality when HAPSTR1 is lost.