Fig. 1: Heat shock induces de novo 7SL expression, nuclear localization, and binding to chromatin.
a Schematic illustration of the evolutionary connection between 7SL and 7SL-related ncRNA (left panel)21. 7SL gives rise to mammalian Alu and B1 SINEs. Human Alu repeats originate from 7SL sequences that have lost their central, 7SL-specific portion followed by Alu domain duplication (right panel)23. Created in BioRender. Bujisic, B. (2025) https://BioRender.com/h93t574. b PRO-Seq analysis40 of nascent 7SL transcription after exposure to 42 °C heat shock for indicated periods of time in mouse embryonic fibroblasts (MEFs). Source data are provided as a Source Data file. c Cell fractionation experiment: 7SL Northern Blot of the cytosolic, nuclear, or total NIH3T3 cells incubated at 37 °C or after 15 min exposure to 45 °C (HS) (upper panel). SYBR gold staining of the gel was used as a loading control (lower panel). d 7SL RNA FISH at 37 °C (pre-HS) or after 1 h exposure to 42 °C (post-HS) in mouse NIH3T3 cells. DAPI staining depicts nuclei. e Total (input), cytosolic, membrane, and nuclear fractions were isolated from NIH3T3 cells incubated at 37 °C or after 15 min exposure to 42, 43, 44, or 45 °C. Immunoblots were performed for SRP72, SRP54, Tubulin (cytosolic marker), and H3K27me3 (nuclear marker). f 7SL CHART-Seq tracks over Rn7s1 and Rn7s2 loci on chromosome 12. Tracks represent the Antisense (AS) signal subtracted for Sense (S) signal for two biological replicates in pre- and post-HS conditions. g Venn diagram demonstrating the number of 7SL CHART-Seq peaks in pre- and post-HS conditions. Peaks were called using MACS91 only if appeared in both biological replicates. h Proportion of 7SL CHART peaks with associated genomic features. Analysis performed using ChIPSeeker92.
