Journal: Cell reports
Article Title: Stem-loop-induced ribosome queuing in the uORF2/ ATF4 overlap fine-tunes stress-induced human ATF4 translational control
doi: 10.1016/j.celrep.2024.113976
Figure Lengend Snippet: Revisiting translational control of human ATF4: Reporters and experimental setup (A) Schematic showing the 5′ end of the mRNA encoding human activating transcription factor 4 ( ATF4 ; NM_182810.2, transcript variant 2), featuring the color-coded Start-stop (St-st) element (yellow), REI-permissive (green) 3-codon uORF1, and inhibitory uORF2 (red) overlapping with the beginning of the main ATF4 ORF, frames 0 and 1. Distances are given in nucleotides. (B) Schematic of the WT CMV-driven ATF4-HA-tagged construct; the HA tag was placed immediately upstream of the ATF4 stop codon. (C) Experimental workflow described in the form of a timeline diagram. PN, Jess protein normalization detection module. (D) All HEK293T cell lysates were subjected to protein separation and immunodetection using the Jess system. The signal, detected in the capillary, is represented as an electropherogram (a single peak of the ATF4-HA tag full-length protein, size of 53 kDa, left) and was automatically quantified (right). Expression of the WT construct under 3 h of Tg stress conditions 8 h post transfection, detected by anti-mouse HA tag antibodies, is shown. (E) Stress-induced upregulation of ATF4-HA protein expression under Tg stress (blue) compared with non-stress conditions (green). Quantified “fold induction” data were plotted (n = 17, right). The differences between experimental groups were tested by a t test. Variables are presented as mean ± SD, and p < 0.05 was considered statistically significant (*p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001). (F) Stress-induced upregulation of the ATF4-HA protein expression from the WT reporter under tunicamycin stress compared with non-stress conditions (set to 1). Quantified “fold induction” data were plotted (n = 3) and analyzed as in (E). (G) Experimental setup illustrating determination of fold change values when comparing (1) each mutant reporter construct vs. the WT construct separately under non-stress (top horizontal arrow) and Tg stress conditions (bottom horizontal arrow) and (2) the fold induction expression of a mutant under stress with the same mutant under non-stress (right vertical arrow) or the WT under stress vs. no stress (blue left vertical arrow). The red diagonal arrow indicates calculated fold induction changes of a given mutant under stress vs. WT under non-stress conditions; i.e., how much each mutant increases or decreases the ~5.2-fold induction of the WT reporter.
Article Snippet: WT ATF4-HA Tag was created by inserting Hind III -Not I digested h ATF4 -wt-HA-Tag (GeneArt String DNA Fragment; Invitrogen) into Hind III -Not I digested pCMV-EGFP-N2 high copy vector. dSt-st was created by inserting the Hind III -Pst I digested fusion PCR product obtained with primers h ATF4 -St-st_AGG-F and h ATF4 -St-st_AGG-R using wt ATF4-HA Tag as a template into Hind III -Pst I digested wt ATF4-HA Tag. d1 was created by inserting the Hind III -Pst I digested fusion PCR product obtained with primers h ATF4 -uORF1_AGG-F and h ATF4- uORF1_AGG-R primers using wt ATF4-HA Tag as a template into Hind III -Pst I digested wt ATF4-HA Tag. d2 was created by inserting the Pst I -EcoR V digested fusion PCR product obtained with primers h ATF4 -uORF2_AGG and SW ATF4 d120 SphI R using wt ATF4-HA Tag as a template into Pst I -EcoR V digested wt ATF4-HA Tag. d-all was created by inserting Hind III -Not I digested h ATF4 -d -all-HA-Tag (GeneArt String DNA Fragment; Invitrogen) into Hind III -Not I digested pCMV-EGFP-N2 high copy vector.
Techniques: Variant Assay, Construct, Immunodetection, Expressing, Transfection, Mutagenesis