Expression profiling by array Genome binding/occupancy profiling by genome tiling array
Summary
Duplication of eukaryotic genomes during S phase is coordinated in space and time. In order to identify zones of initiation and cell-type as well as gender-specific plasticity of DNA replication, we profiled replication timing, histone acetylation and transcription throughout the Drosophila genome. We observed two waves of replication initiation with many distinct zones firing in early and multiple, less defined peaks at the end of S phase, suggesting that initiation becomes more promiscuous at the end of S phase. A comparison of different cell types revealed widespread plasticity of replication timing on autosomes. Most occur in large regions but only half coincide with local differences in transcription. In contrast to confined autosomal differences, a global shift in replication timing occurs throughout the single male X chromosome. Unlike in females, the dosage compensated X chromosome replicates almost exclusively early. This difference occurs at sites which are not transcriptionally hyperactivated, but show increased acetylation of lysine 16 of histone H4. This suggests a transcription-independent, yet chromosome-wide process related to chromatin. Importantly, H4K16ac is also enriched at initiation zones as well as early replicating regions on autosomes during S phase. Together, our data reveal novel organizational principles of DNA replication of the Drosophila genome and imply chromatin structure as a determinant of replication timing locally and chromosome-wide.
Keywords: cell type comparison, chip-chip, replication timing
Overall design
RNA was isolated from Kc and Cl8 cells (5 replicates each) and hybridized to gene expression arrays. RNA was isolated from kc ane Cl8 cells (2 replciates each) and hybridised to tiling arrays. Early and late replicating DNA was isolated from Kc (5 replicates), Cl8 (2 replicates) and S2 (2 replicates) cells and hybridized to tiling arrays. Replicating DNA from four S phase fractions ( 2 replicates each) was isolated from Kc cells and hybridized to tiling arrays, with genomic DNA (2 replicates) from Kc cells as a control. Nascent DNA was isolated from Kc cells and hybridized to tiling arrays, with genomic DNA as a control (3 replicates each). ChIP-chip was perfomred for RNA Polymerase II in Kc (2 replicates) and Cl8 (3 replicates) cells. ChIP-chip was performed for H4K16ac in Kc (3 replicates) and Cl8 (4 replicates) cells. ChIP-chip for H4K16ac was performed in early and late S phase Kc cells (2 replicates each).
HMM based differentially replicating regions Kc-Cl8 header descriptions
chromosome
GSM336362 minus GSM336363 was used as input for Hidden Markov Model segmentation to define those regions which are marked by the chromosomal coordinates.
start
GSM336362 minus GSM336363 was used as input for Hidden Markov Model segmentation to define those regions which are marked by the chromosomal coordinates.
end
GSM336362 minus GSM336363 was used as input for Hidden Markov Model segmentation to define those regions which are marked by the chromosomal coordinates.
Cl8-Kc transcription
GSM336365
HMM switch.type
GSM336362 minus GSM336363 was used as input for Hidden Markov Model segmentation to define the replciation switch chracteristics of those regions which are marked by the chromosomal coordinates.
Kc replication timing
GSM336362
Cl8 replication timing
GSM336363
Kc-Cl8 replication timing
GSM336362 - GSM336363
H4K16.Kc
GSM336366
H4K16.Cl8
GSM336367
Kc.Pol2
GSM336368
Cl8.Pol2
GSM336369
significant replication timing switch
Columns B,C,E,H
Data table
chromosome
start
end
Cl8-Kc transcription
HMM switch.type
Kc replication timing
Cl8 replication timing
Kc-Cl8 replication timing
H4K16.Kc
H4K16.Cl8
Kc.Pol2
Cl8.Pol2
significant replication timing switch
chr2L
88
59289
4.093323843
Cl8 early
0.451866192
1.95583274
-1.503966548
0.793620403
0.291880783
0.479523132
-0.003978648
L>E
chr2L
59290
69080
0.853916667
unchanged
2.986703557
2.416798419
0.569905138
0.885680556
0.167833333
0.3179375
0.109597222
no diff
chr2L
69081
73225
0.288018018
Kc early
3.50536
2.67152
0.83384
2.383423423
2.113738739
0.754774775
1.206426426
chr2L
73226
75009
3.132941176
unchanged
3.829046154
2.938307692
0.890738462
2.013333333
1.573284314
0.809411765
1.510326797
no diff
chr2L
75010
80227
1.666853147
Kc early
4.045044586
2.869267516
1.17577707
0.694405594
1.110541958
-0.236083916
-0.07018648
chr2L
80228
94816
0.178897243
unchanged
3.381529126
2.681347087
0.700182039
-0.236875522
-0.038609023
-0.055839599
-0.096424394
no diff
chr2L
94817
137875
-0.979508475
Kc early
4.746492875
3.363537301
1.382955574
1.492319209
1.302432203
0.710728814
0.848570621
chr2L
137876
139255
-0.156842105
unchanged
3.248115385
2.361634615
0.886480769
-0.07745614
-0.635921053
0.277894737
-0.17745614
no diff
chr2L
139256
149855
-0.425670103
Kc early
4.773921311
3.592704918
1.181216393
1.015189003
0.903599656
0.215635739
0.18975945
chr2L
149856
178485
-0.697539474
unchanged
3.335279793
3.043458549
0.291821244
0.973855263
1.320052632
0.604243421
0.830368421
no diff
chr2L
178486
194803
3.061181818
Cl8 early
2.627340807
3.331087444
-0.703746637
0.287598485
1.208534091
0.058659091
-0.008030303
chr2L
194804
216381
2.665387205
unchanged
2.900705107
2.983739703
-0.083034596
1.247861953
1.445147306
0.098636364
0.182205387
no diff
chr2L
216382
288502
0.822900763
Cl8 early
1.003449671
2.294876075
-1.291426404
0.998497031
1.162025445
0.378290076
0.552743003
chr2L
288503
299595
-1.485775578
unchanged
1.34021519
1.489208861
-0.148993671
1.345170517
1.484983498
0.87669967
1.232123212
no diff
chr2L
299596
398354
-0.14000408
Cl8 early
-0.271064123
1.108348214
-1.379412338
-0.211984224
-0.144380865
-0.122829457
0.044667483
chr2L
398355
419415
-2.806712803
unchanged
2.631583756
2.477411168
0.154172589
0.900790081
0.698719723
0.251487889
0.414625144
no diff
chr2L
419416
429784
-1.309507042
Kc early
3.692430976
2.652946128
1.039484848
2.291431925
2.138565141
0.991003521
0.933262911
chr2L
429785
455986
-0.981060172
unchanged
3.855099859
3.23757384
0.61752602
0.69469914
0.721278653
0.311074499
0.289226361
no diff
chr2L
455987
466648
0.114261745
Kc early
4.523955128
3.42724359
1.096711538
0.074876957
0.308850671
-0.307315436
-0.094194631
chr2L
466649
467748
0.213548387
unchanged
4.632
3.741931818
0.890068182
-0.334086022
-0.548951613
-0.513548387
-0.239784946
no diff
Total number of rows: 4667
Table truncated, full table size 614 Kbytes.
Kc initiation zones header descriptions
chromosome
GSM336362
init.start
GSM336362
init.end
GSM336362
initiation zone transcription
GSM336365
initiation zone replication timing
GSM336362
repl.start
GSM336362
repl.end
GSM336362
peaks.smooth
GSM336362
peak.rt.smooth
GSM336362
p-value
GSM336362
adjusted p-value
p-value after correction for multipe testing using the Benjamini-Hochberg method
nascent DNA
GSM336364
H4K16ac
GSM336366
RNA Polymerase II
GSM336368
Data table
chromosome
init.start
init.end
initiation zone transcription
initiation zone replication timing
repl.start
repl.end
peaks.smooth
peak.rt.smooth
p-value
adjusted p-value
nascent DNA
H4K16ac
RNA Polymerase II
chr2L
14088
23588
-0.508829431
0.567266667
88
35088
18588
0.532621899
2.03E-05
3.77E-05
2.748026756
0.93657748
0.515367893
chr2L
67588
75088
4.450338164
3.630463768
44088
86088
72588
3.849030396
0.002031086
0.002866552
1.742657005
2.340048309
0.665724638
chr2L
121588
127088
7.222039474
5.389333333
86588
139088
124088
5.403278198
3.07E-07
7.95E-07
1.651052632
1.87372807
0.068026316
chr2L
143588
151588
0.49716895
4.54886758
139588
180088
147588
4.641239296
6.37E-06
1.28E-05
0.114748858
1.182907154
0.099908676
chr2L
192588
201088
17.90402542
3.289322034
180588
255088
197588
3.23160269
1.09E-07
3.22E-07
0.338559322
0.675254237
-0.023707627
chr2L
282088
290088
0.652690583
1.660053571
255588
335588
287088
1.594783391
3.58E-07
9.08E-07
0.628878924
1.666741405
0.958923767
chr2L
352588
360088
1.743046875
-0.612484375
336088
373588
356588
-0.441657783
5.04E-10
2.37E-08
1.829375
0.564791667
0.232421875
chr2L
424588
430088
-0.613856209
4.206562092
374088
437088
427588
3.95732137
0.001939703
0.002748273
0.209084967
1.479172113
0.096764706
chr2L
461588
467088
-1.210974026
4.725587097
437588
473588
464588
4.532305954
5.58E-06
1.13E-05
-1.012857143
-0.186428571
-0.345876623
chr2L
485088
493088
1.15
5.689769585
474088
500588
490088
5.349659174
2.74E-08
9.95E-08
1.821336406
0.963072197
0.719470046
chr2L
506588
514588
2.746233184
5.253705357
501088
543088
511588
5.133195869
0.000178275
0.000290154
-0.058789238
-0.257294469
-0.299349776
chr2L
545588
553588
1.170678733
3.976552036
543588
638088
547588
3.934505973
0.000202293
0.000326523
-1.406606335
0.314434389
0.979072398
chr2L
638588
645588
-1.050833333
-2.67590625
638588
648088
643088
-2.711500597
0.008755873
0.011132279
-0.86328125
-0.373923611
-0.154140625
chr2L
655588
661088
-0.572857143
-2.589662162
648588
669088
658088
-2.700490838
0.004361188
0.005824859
-0.07877551
-0.46521542
-0.120646259
chr2L
682588
689588
-0.702704918
-2.350704918
669588
705088
685588
-2.304691007
1.67E-09
2.41E-08
-0.816065574
-0.325
-0.01057377
chr2L
714088
722088
-0.562803738
-2.814971963
710088
739588
718588
-2.934278118
0.000180198
0.000292721
-0.450934579
-0.404205607
-0.149953271
chr2L
750088
758088
-0.666457399
-2.406910714
740088
766088
754088
-2.598342043
2.54E-08
9.39E-08
-1.148609865
-0.375590433
-0.11206278
chr2L
836588
845588
0.385731707
3.580455285
766588
845588
842088
3.563536732
0.003609615
0.004885295
0.240121951
0.892344173
-0.035792683
chr2L
857088
865588
-0.007118644
4.048898305
846088
889088
862588
3.980979294
1.26E-07
3.63E-07
-0.482838983
1.477048023
0.026419492
chr2L
889588
897088
1.632392344
3.29707177
889588
947588
892088
3.219640169
0.0458728
0.052019223
-0.370430622
0.619792663
0.390119617
Total number of rows: 2539
Table truncated, full table size 351 Kbytes.
Kc termination zones header descriptions
chromosome
GSM336362
termination.start
GSM336362
termination.end
GSM336362
termination zone transcription
GSM336365
termination zone replication timing
GSM336362
repl.start
GSM336362
repl.end
GSM336362
peaks.smooth
GSM336362
end.rt.smooth
GSM336362
p-value
GSM336362
adjusted p-value
p-value after correction for multipe testing using the Benjamini-Hochberg method