Journal: Nature Cell Biology
Article Title: Dynamic de novo heterochromatin assembly and disassembly at replication forks ensures fork stability
doi: 10.1038/s41556-023-01167-z
Figure Lengend Snippet: a , Left: representative images of PLA depicting H3K9me3 presence at replication sites (H3K9me3-EdU PLA, red). Nuclei were counterstained with DAPI (blue). Right: distribution of the total intensity of all H3K9me3-EdU PLA spots per nucleus in wild-type cells (WT), G9a knockout cells (G9a−/−) and wild-type cells treated with 1 µM UNC0642 (UNC0642). Cells were labelled with EdU for 20 min and were either left untreated (UT), treated with 1 mM HU for 1 h (HU) or treated with 1 mM HU for 1 h and released from HU for 25 min and labelled with EdU for 20 min (Rel). ( n WT-UT = 2,436, n WT-HU = 2,212, n WT-REL = 2,340, n G9aKO-UT = 1,038, n G9aKO-HU = 1,168, n G9aKO-REL = 1,074, n UNC0642-UT = 2,413, n UNC0642-HU = 2,328, n UNC0642-REL = 2,315 cells analysed). b – d , Same as a but showing the distribution of PLA spot intensity per nucleus for H3K9me1-EdU PLA ( n WT-UT = 1,346, n WT-HU = 1,050, n WT-REL = 1,192, n G9aKO-UT = 1,543, n G9aKO-HU = 1,470, n G9aKO-REL = 1,630, n UNC0642-UT = 1,502, n UNC0642-HU = 1,296, n UNC0642-REL = 1,338 cells analysed) ( b ), H3K9me2-EdU PLA ( n WT-UT = 1,442, n WT-HU = 1,431, n WT-REL = 1,338, n G9aKO-UT = 1,321, n G9aKO-HU = 1,381, n G9aKO-REL = 1,380, n UNC0642-UT = 1,367, n UNC0642-HU = 1,490, n UNC0642-REL = 1,411 cells analysed) ( c ) and G9a-EdU PLA ( n WT-UT = 1,407, n WT-HU = 1,086, n WT-REL = 1,502, n G9aKO-UT = 1,510, n G9aKO-HU = 1,513, n G9aKO-REL = 1,510, n UNC0642-UT = 1,504, n UNC0642-HU = 1,505, n UNC0642-REL = 1,501 cells analysed) ( d ). e , Distribution of H3K9me3-EdU (left) or G9a-EdU (right) total PLA spot intensity per nucleus of wild-type cells treated (ATRi+) or not (ATRi−) with 10 µM ATR inhibitor and EdU labelled for 20 min followed by a 1 mM HU treatment for 1 h. For H3K9me3-EdU PLA: n HU− = 909, n HU+ = 931; for G9a-EdU PLA: n HU− = 869, n HU+ = 1,080 cells analysed. f , Same as a but showing the distribution of H3K9me3-EdU total PLA spot intensity per nucleus for the indicated conditions ( n ctl-UT = 1,509, n ctl-HU = 1,509, n ctl-REL = 1,506, n UNC0642-UT = 2,003, n UNC0642-HU = 1,529, n UNC0642-REL = 1,543, n siSUV39h1-UT = 1,514, n siSUV39h1-HU = 1,502, n siSUV39h1-REL = 1,500, n UNC0642+siSUV39h1-UT = 1,502, n UNC0642+siSUV39h1-HU = 1,523, n UNC0642+siSUV39h1-REL = 1,507, cells analysed) (note that, for a – f , blue dashed indicates mean of the distribution, **** P ≤ 0.0001, *** P ≤ 0.001, ** P ≤ 0.01, * P ≤ 0.05, NS, non-significant, one-way analysis of variance Kruskal–Wallis test followed by Dunn’s test is used for all statistical analysis). g , Model summarizing G9a and SUV39h1 role at stalled replication forks. Upon replication stress, checkpoint-regulated G9a activity at stressed replication forks results in transient accumulation of H3K9me1/2 allowing SUV39h1 to catalyse H3K9me3 modification. Further accumulating HDAC1 resulted in the loss of H4K16ac. Figure created with biorender.com . h , Representative images of the changes over time of a stripe of photo-activated GFP-H2A for the indicated conditions. This experiment was reproduced independently three times with similar results. i , Mean photo-activated GFP-H2A area over time relative to the area at T = 0 min in percentage ± standard deviation. In PCNA negative (black) and positive (red) for untreated cell: WT-UT (left), cells undergoing replication stress: WT + HU (middle) and cells undergoing replication stress in the absence of G9a activity (right). Unpaired two-sided t -test, **** P ≤ 0.0001, ** P ≤ 0.01. For experimental design, see Extended Data Fig. . n = 3 independent experiments. Source numerical data are available in .
Article Snippet: Primary antibodies used for PLA are: Anti-Biotin antibody (A150-109A, Bethyl Laboratories), Anti-Biotin antibody (AB_2339006, JacksonImmunoResearch), Anti-H3K9me3 (EPR16601) (Ab176916, Abcam), Anti-H3K9me2 (Ab1220, Abcam), Anti-H3K9me1 (EPR16989) (Ab176880, Abcam), Anti-G9a (EPR18894) (Ab 185050, Abcam), Anti-HDAC1 (Ab19845, Abcam), Anti-BRCA1 (D-9) (SC6954, Santa Cruz Biotechnology), Anti-BARD1 (A300-263A, Bethyl), Anti-RPA32/RAP2 (9H8) (Ab2175, Abcam), Anti-PCNA (PC10) (ab29, Abcam), Anti-H4K20me0 (EPR22116) (Ab227804, Abcam), Anti-H4K16ac (EPR1004) (Ab109463, Abcam), Anti-RAD51 (70-002, Bio Academia), Anti- H2AK15 ub (EDL H2AK15-4) (MABE1119, Millipore).
Techniques: Knock-Out, Activity Assay, Modification, Standard Deviation