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10/29/15 1 Genomics of Gene Regula0on 2: Conserva0on, Integra0on of features, Assays, Issues in interpreta0on CSHL Course in Computa0onal and Compara0ve Genomics 2015 Ross Hardison 10/29/15 1 Features of cis regulatory modules (CRMs) 10/29/15 2 Hardison &Taylor (2012) Nature Reviews Gene/cs 13: 469483 a. Bound and unbound motif instances b. Transcription factors and histone modifications characteristic of different CRMs

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10/29/15

1

Genomics  of  Gene  Regula0on  2:  Conserva0on,  Integra0on  of  features,  Assays,  

Issues  in  interpreta0on  

CSHL  Course  in  Computa0onal  and  Compara0ve  Genomics    2015  

Ross  Hardison  

10/29/15 1

Features  of  cis-­‐regulatory  

modules  (CRMs)  

10/29/15 2 Hardison  &Taylor  (2012)  Nature  Reviews  Gene/cs  13:  469-­‐483    

a.  Bound and unbound motif instances

b.  Transcription factors and histone modifications characteristic of different CRMs

10/29/15

2

CONSERVATION  OF  SEQUENCE  AND  EPIGENETIC  FEATURES  OF  CRMS  

10/29/15 3

Methods  for  predic0ng  CRMs  

Hardison  &Taylor  (2012)  Nature  Reviews  Gene/cs  13:  469-­‐483    10/29/15 4

10/29/15

3

Erythroid  enhancer,  HS2  of  HBB  locus  control  region  

Window Positionchr11:

Short Match

SINELINELTRDNA

SimpleLow Complexity

SatelliteRNA

OtherUnknown

Human Feb. 2009 (GRCh37/hg19) chr11:5,301,795-5,302,089 (295 bp)5,301,850 5,301,900 5,301,950 5,302,000 5,302,050

HS2_pos

K562 Sg 1

PBDE GAT1 UCD

K562 Sig149 -

1 _

Mammal Cons

NFE2  KLF1  

TAL1  GATA   TFs  bound  

DNase  footprints  

Mammalian  constraint  

ChIP-­‐seq  GATA1  PBDE  

DNase  HS  Match  WGATAR  

10/29/15 5

But  not  all  CRMs  are  that  obvious…  

Evolu0onary  constraint  on  SOME  enhancers  

•  Occupancy  of  transcrip0on  factors  is  conserved  in  mouse  and  humans  •  Strong  evidence  for  evolu0onary  constraint  on  the  DNA  sequence  •  Preserva0on  of  the  TF  binding  site  mo0fs  across  mammals  

Hardison  &Taylor  (2012)  Nature  Reviews  Gene/cs  13:  469-­‐483    10/29/15 6

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4

Mo0f  turnover  at  SOME  enhancers  

•  Occupancy  of  transcrip0on  factors  is  conserved  in  mouse  and  humans  •  More  localized  evolu0onary  constraint  on  the  DNA  sequence  •  Preserva0on  of  one  TF  binding  site  mo0fs  across  mammals,  but  second  mo0f  is  in  

different  loca0on  in  rodents  compared  to  other  mammals  (lineage-­‐specific)  

Hardison  &Taylor  (2012)  Nature  Reviews  Gene/cs  13:  469-­‐483    10/29/15 7

Lineage  specific  evolu0on  of  SOME  enhancers  

•  Occupancy  of  transcrip0on  factors  only  in  mouse,  not  human  •  No  evidence  for  evolu0onary  constraint  on  the  DNA  sequence  •  Preserva0on  of  one  TF  binding  site  mo0f  in  rodents  and  laurasiatherians  (dog,  

horse,  cow),  but    not  in  humans  (lineage-­‐specific  loss  of  binding?)  

Hardison  &Taylor  (2012)  Nature  Reviews  Gene/cs  13:  469-­‐483    10/29/15 8

10/29/15

5

Different  approaches  to  finding  func0on  

9 ENCODE  Project  Consor0um  "Defining  func0onal  elements  in  the  human  genome”  (2014)  PNAS  

10/29/15

How  similar  are  pacerns  of  gene  expression  between  human  and  mouse?  

10/29/15 10 Mouse  ENCODE  Project  Consor0um   (2014)  Integrated  Encyclopedia  of  mouse  DNA  elements.  Nature  

10/29/15

6

Dis0nctly  different  expression  pacerns  

10/29/15 11 Mouse  ENCODE  Project  Consor0um   (2014)  Integrated  Encyclopedia  of  mouse  DNA  elements.  Nature  

Genes  with  high  variance  between  0ssues  

Genes  with  high  variance  between  species  

Conserva0on:  Sequence-­‐level  and  ac0vity-­‐level  

12

About  40%  of  regulatory  DNA  (TFBS,  DHS)  in  mouse  maps  to  aligning  DNA  in  human.  About  10%  of  TF-­‐bound  DNA  in  mouse  is  also  bound  by  the  same  TF  in  human.  

Olgert  Denas,  Richard  Sandstrom,  Yong  Cheng,  Kathryn  Beal,  Javier  Herrero,  Ross  Hardison,  James  Taylor,  (2015)  BMC  Genomics.  Genome-­‐wide  compara0ve  analysis  reveals  human-­‐mouse  regulatory  landscape  and  evolu0on.    

10/29/15

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Genomic  DNA  segments  occupied  by  orthologous  pairs  of  TFs  

13

Conserved  loca0ons  rela0ve  to  TSS  

Yong  Cheng  et  al.,  Snyder,  Hardison,  Pennacchio  labs  (2014)  .  Principles  of  Regulatory  Informa0on  Conserva0on  Revealed  by  Comparing  Mouse  and  Human  Transcrip0on  Factor  Binding  Profiles.  Nature  

Conserved  binding  site  mo0fs  

10/29/15

Conserved  and  divergent  occupancy  of  orthologous  DNA  segments  

10/29/15 14

Yong  Cheng  et  al.,  Snyder,  Hardison,  Pennacchio  labs  (2014)  .  Principles  of  Regulatory  Informa0on  Conserva0on  Revealed  by  Comparing  Mouse  and  Human  Transcrip0on  Factor  Binding  Profiles.  Nature  

10/29/15

8

Conserva0on  of  GATA1-­‐occupancy  between  mouse  and  human  

15

Window Positionchr1:

Mouse July 2007 (NCBI37/mm9) chr1:156,885,743-156,887,787 (2,045 bp)156,886,500 156,887,000 156,887,500

hs1862_heart

G1E-ER GATA1 24hr

Erythrobl GATA1

MEL GATA-1

Mammal Cons

Window Positionchr1:

--->Gaps

HumanOrangutan

RhesusMarmoset

Mouse_lemurMouse

RatGuinea_Pig

CowHorse

DogElephant

TenrecArmadillo

SlothOpossumPlatypusChicken

Lizard

Human Feb. 2009 (GRCh37/hg19) chr1:181,122,256-181,122,304 (49 bp)181,122,270 181,122,280 181,122,290 181,122,300

CAGA ACGT T CC T T A T C T C T C TGCA GCAGGACGC TGA T A A T C TGCCCAGC3

CAGA ACGT T CC T T A T C T C T C TGCA GCAGGACGC TGA T A A T C TGCCCAGCCAGA ACGT T CC T T A T C T C T C TGCA GCAGGACGC TGA T A A T C TGCCCAGCCAGA ACGT T CC T T A T C T C TGTGCA GCAGGACGC TGA T A A T C TGCCCAGCCAGA ACGT T CC T T A T C T C T C TGCA GCAGGACGC TGA T A A T C TGCCCAGCCAGA ACGT T CC T T A T C T CC T TGCA GCAGGGC T C TGA T A A T C TGCCGG T TCAGA A TGGT CC T T A T C T C T T TGCA GCAGGAC T C TGA T AGT C TGCCCCA TCAGA A TGGT CC T T A T C T C T T TGCA GCAGGAC T C TGA T AGT C TGCCCCA TCA A A ACGT T CC T T A T C T C T T TGT A GCAGGAC T C TGA T A A T C TGCCCCC TCAGG - CG T T CC T T A T C T C T TGGC T GCAGGGT T C T CA T A A TGTGCCCAG TCGGGT CG T T CC T T A T C T C T T TGCA GCAGGGT T C TGA T A A T C TGCCCAG TCAGGACGT T CC T T A T C T C T C TGCA GCAGGGT T C TGA T A A TGCGCCC AG TCAGA A TGT T CC T T A T C T C T TGGC A C CAGGGC T - TGA T AGT CAGCCAGG TCA A A A TGT T CC T T A T C T C T TGGC A C CAGGGC T C TGA T A A T TGGCCAGG TCAGA A TGT CCC - T A T C T C T CGGCC C CA - GGCCC TGGT A A T C TGC T CGGCCAGA ACGT T CC - T A T C T C T TGGT T C CAGGGC T C TGA T A A T C TGCC TGGCCAGA A TGT T CCCCA T CGCC T C T CA C CGGGGCA T TGA T A AGC T ACCA T C TCAGA ACA T T CCC TGT CAC T T CGC A C CAGGGCA T TGA T A A A T T T T C T CC C

Window Positionchr1:

Human Feb. 2009 (GRCh37/hg19) chr1:181,121,049-181,123,654 (2,606 bp)181,121,500 181,122,000 181,122,500 181,123,000 181,123,500

hs1862

K562 GATA1 Sg

PBDE GATA1 Sg

Mammal Cons

Mo0fs  for  GATA  factor  binding  preserved  across  mammals  10/29/15

Conserva0on  of  TF  occupancy  predicts  enhancers  ac0ve  in  mul+ple  0ssues  

16

Model:  Pleiotropic  func0ons  (mul0ple  0ssues,  mul0ple  TFs  binding)  are  subject  to  stronger  constraint,  leading  to  preserva0on  of  occupancy  despite  tendency  of  regulatory  regions  to  “turn  over”  

Yong  Cheng  et  al.,  Snyder,  Hardison,  Pennacchio  labs  (2014)  .  Principles  of  Regulatory  Informa0on  Conserva0on  Revealed  by  Comparing  Mouse  and  Human  Transcrip0on  Factor  Binding  Profiles.  Nature  10/29/15

10/29/15

9

GATA  factor  

Tissue  

Erythroid,  Megakaryocyte  

T-­‐lymphocytes   Heart   Brain   Vasculature   Liver   Pancreas   Lung   Intes/ne   Ovary   Tes/s  

GATA1   +  GATA2   +   +   +  GATA3   +   +   +  GATA4   +   +   +   +   +  GATA5   +  GATA6   +   +   +   +   +   +   +  FOG1   +  FOG2   +   +   +   +  

Enhancers  predicted  by  conserved  GATA1  binding  are  ac0ve  in  0ssues  with  paralogous  GATA  factors  

Hypothesis:  The  same  GATA  factor-­‐dependent  enhancer  is  used  in  erythroid  (GATA1),  heart  (GATA4)  and  brain  (GATA3)  for  different  targets.   17 10/29/15

Non-­‐erythroid  func0on  of  GATA1-­‐bound  sites  could  result  from  binding  of  paralogs  (e.g.  GATA4)  to  same  site  in  other  0ssues  

10/29/15 18

Window Positionchr3:

Mouse Dec. 2011 (GRCm38/mm10) chr3:84,438,567-84,482,797 (44,231 bp)84,445,000 84,450,000 84,455,000 84,460,000 84,465,000 84,470,000 84,475,000 84,480,000

Fhdc1Fhdc1

Fhdc1

GSM746581_2_Gata1.bw

226 -

0 _

GSM1151146_Gata1.bw

74 -

0 _

GSM558904_Gata4.bw

181 -

0 _

GSM558909_Ep300.bw

49 -

0 _

ERY  GATA1  

ERY  GATA1  

Heart  GATA4  

Heart  EP300  

Gocgens,  CODEX      hcp://codex.stemcells.cam.ac.uk  

10/29/15

10

GAIN-­‐OF-­‐FUNCTION  ENHANCER  ASSAYS  

10/29/15 19

TF  OCCUPANCY  IS  A  GOOD  PREDICTOR  OF  ERYTHROID  ENHANCERS:  TAL1  

Nergiz  Dogan  

10/29/15 20

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11

TAL1  +  GATA1  =  induc0on  

10/29/15 21

Tripic  et  al  (2009)  Blood  113:  2191      Cheng  et  al  (2009)  Genome  Res.  19:  2172    Wu  et  al  (2011)  Genome  Res.  21:  1659  

Epigene0c  signatures  can  predict  enhancers  with  high  accuracy  

10/29/15 22 Dogan  et  al  (2015)  Epigene/cs  &  Chroma/n  8:  16  

10/29/15

12

What  dis0nguishes  enhancer  ac0ve  vs  inac0ve  TAL1  OSs?  

Scalechr18:

1 kb mm932,701,500 32,702,000 32,702,500 32,703,000

TAL1_2105

150 _

1 _

Scalechr1:

1 kb mm9135,722,000 135,722,500 135,723,000

TAL1_201

150 _

1 _

6.27

0.39

Fold  change  in    ac0vity  ChIP-­‐seq  signals  of  TAL1  peaks  

10/29/15 23 Dogan et al. (2015) Epigenentics & Chromatin 8: 16.

Clusters  of  feature  combina0ons  contribute  differen0ally  to  measured  enhancement  

10/29/15 24

Dogan et al. (2015) Epigenentics & Chromatin 8: 16.

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13

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TF  occupancy:  frequently  ac0ve  as  enhancers  HMs  without  TFs:  rarely  ac0ve  as  enhancers  

Dogan  et  al.  (2015)  Epigene/cs  &  Chroma/n  8:  16.  

n=  273  

INTEGRATIVE  ANALYSES  ENCODE  consor0um  

10/29/15 26

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14

“Paint”  genomic  regions  by  dominant  histone  modifica0ons:  mul0variate  HMM  

10/29/15 27 Ernst and Kellis (2010) Nature Biotechnology 28: 817… Wu et al. 2011 Genome Res 21: 1659-1671

Integrate  features  using  mul0variate  segmenta0ons  

10/29/15 28 M. Hoffman, J. Ernst et al. 2013. Integrative segmentations of function-associated marks. Nucleic Acids Res.

10/29/15

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Enhancer  predicted  from  HMM  segmenta0on  based  on  histone  modifica0ons  

10/29/15 29

ENCODE  Project  Consor0um:  Combined  segmenta0on  results  from  chromHMM  (Ernst  et  al)  and  Segway  (Hoffman  et  al)  to  generate  25-­‐state  models  from  histone  modifica0ons  and  other  epigene0c  features.    Use  state  with  enhancer-­‐associated  state  to  predict  CRMs.  Test  in  mice  and  fish.  

ENCODE  Project  Consor0um  (2012)  Nature  

DNase  HSs  

Accurate  predic0ons  of  enhancers  

10/29/15 30

Transient transgenic mouse embryo

Circulating erythrocytes with GFP in transgenic Medaka fish

ENCODE  Project  Consor0um  (2012)  Nature  

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MASSIVELY  PARALLEL  ENHANCER  ASSAYS  

S0ll  use  the  genomics  and  epigenomics,  but  ramp  up  the  scale  of  assays  

10/29/15 31

CRE-­‐seq  

10/29/15 32

Kwasnieski,  J.C.  et  al.  (B.A.  Cohen)  2012.  PNAS  USA  109:19498–19503  

Similar  assays  from  Shendure  and  Mikkelson  groups  

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17

CRE-­‐seq:  For  DNA  segments  with  CBX  binding  site  mo0fs,  occupancy  by  CBX  correlates  with  enhancer  ac0vity  

10/29/15 33

White,  Myers,  Corbo,  Cohen  (2013).  PNAS  USA  110:11952-­‐11957  

Reproducible expression measurements show differences in expression by segmentation class.

Kwasnieski J C et al. Genome Res. 2014;24:1595-1602

© 2014 Kwasnieski et al.; Published by Cold Spring Harbor Laboratory Press 10/29/15 34

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Frac0on  of  “predic0ons”  that  are  ac0ve  in  CRE-­‐seq  

10/29/15 35

Kwasnieski J C et al. Genome Res. 2014;24:1595-1602

Combina0on:  STARR-­‐seq  of  predicted  CRMs  

10/29/15 36

Feng  Yue  with  Mouse  ENCODE  (2014).  Nature  

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19

MACHINE  LEARNING  APPROACHES  TO  FINDING  CRMS  

10/29/15 37

EnhancerFinder  integrates  diverse  datasets  to  predict  developmental  enhancers  

10/29/15 38 Erwin  et  al  (K.  Pollard)  2014.  PLoS  Comp  Biol  10:  e1003677    

mo0fs  

constraint  epigene0c  1  

epigene0c  2  epigene0c  3  

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EnhancerFinder:  Two  stage  predic0ons  

10/29/15 39 Erwin  et  al  (K.  Pollard)  2014.  PLoS  Comp  Biol  10:  e1003677    

Single  marks  work,  but  integra0on  improves  predic0on  

10/29/15 40 Erwin  et  al  (K.  Pollard)  2014.  PLoS  Comp  Biol  10:  e1003677    

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Examples  of  successful  enhancer  predic0ons  

10/29/15 41 Erwin  et  al  (K.  Pollard)  2014.  PLoS  Comp  Biol  10:  e1003677    

DIRECT  SELECTION  FOR  ACTIVITY  TO  FIND  ENHANCERS  

Forget  the  genomics  and  bioinforma0cs  …  

10/29/15 42

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STARR-­‐seq:  Self-­‐transcribing  ac0ve  regulatory  region  sequencing  

10/29/15 43

Arnold  et  al  (A.  Stark)  2013.  Science    339:  1074-­‐1077    

Other  methods  of  screening  for  enhancer  ac0vity  on  a  large  scale  

10/29/15 44

Murtha,  M.  et  al.  Nat.  Methods  11,  (2014).    Dickel,  D.E.  et  al.  Nat.  Methods  11,  (2014).  Hardison,  R.C.  Nat.  Methods  11,  News&Views  (2014).  

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LOSS-­‐OF-­‐FUNCTION  ENHANCER  ASSAYS  

10/29/15 45

Exploi0ng  nature’s  variants  for  novel  avenues  to  therapy  

10/29/15 46 Hardison  and  Blobel  (2013)  Science  342:  206;  commen0ng  on  ar0cle  by  Bauer  et  al.  same  issue  

10/29/15

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CRISPR-­‐Cas9  to  engineer  close  to  satura0on  mutagenesis  

10/29/15 47

Canver  et  al.  …  Zhang,  Orkin,  Bauer  (2015)  BCL11A  enhancer  dissec0on  by  Cas9-­‐mediated  in  situ  satura0ng  mutagenesis.  Nature,  published  online  Sept  16  

Find  region  of  candidate  enhancer  that  is  needed  for  ac0vity  

10/29/15 48

Canver  et  al.  …  Zhang,  Orkin,  Bauer  (2015)  Nature,  published  online  Sept  16  

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Fine  mapping  of  “Achilles  heel”  of  enhancer  

10/29/15 49 Canver  et  al.  …  Zhang,  Orkin,  Bauer  (2015)  Nature,  published  online  Sept  16  

Highly  constrained  noncoding  sequences  are  frequently  0ssue-­‐specific  enhancers  

Pennacchio et al. (2006) Nature 444: 499-502 10/29/15 50

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Implications of enhancer activities in highly constrained sequences

• Non-­‐coding  regions  that  are  conserved  at  an  unusually  high  level  are  highly  enriched  in  enhancers  located  near  developmental  genes  

• We  should  be  able  to  predict  many  enhancer  regions  based  on  strong  sequence  constraint  

Assump/on:    These  regions  are  sequence  constrained  because  of  func/onal  constraint  

Slides  edited  from:  Jonathan  McGovern  

BMMB  541  4/30/09  

 10/29/15 51

Dele/on  of  Ultraconserved  Elements  Yields  Viable  Mice  

Nadav  Ahituv,  Yiwen  Zhu,  Amy  Holt,  Veena  Afzal,  Len  A.  Pennacchio  and  Edward  Rubin  

PLoS  Biology,  September  2007  

But…

10/29/15 52

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Selection of Ultraconserved Enhancers KO PHENOTYPE KO PHENOTYPE

• Dmrt1:  Male  sexual  development  abnormali0es  

 

 

• Pax6:    Eye  defects,  lethality,  CNS,  craniofacial,  pituitary  and  pancrea0c  abnormali0es    

• DNA  polymerase:    Assumed  Lethal  

• ATP11C:  Assumed  Lethal    

• Dmrt3:    Male  sexual  development  abnormali0es,  lethal  due  to  dental  malforma0on        • WT1:    Wilms  tumor,  kidney  defects,  lethality,  mesothelium  defects,  heart/lung  malforma0on  

• ARX:    Lethality,  male  sexual  development  abnormali0es,  small  brain  

• Sox3:    Abnormal  sexual  development  and  pituitary  func0on,  mental  retarda0on  in  humans  10/29/15 53

Successful Knock-Out KO PHENOTYPE KO PHENOTYPE

• Dmrt1:  Male  sexual  development  abnormali0es  

 

 

• Pax6:    Eye  defects,  lethality,  CNS,  craniofacial,  pituitary  and  pancrea0c  abnormali0es    

• DNA  polymerase:    Assumed  Lethal  

• ATP11C:  Assumed  Lethal    

• Dmrt3:    Male  sexual  development  abnormali0es,  lethal  due  to  dental  malforma0on        • WT1:    Wilms  tumor,  kidney  defects,  lethality,  mesothelium  defects,  heart/lung  malforma0on  

• ARX:    Lethality,  male  sexual  development  abnormali0es,  small  brain  

• Sox3:    Abnormal  sexual  development  and  pituitary  func0on,  mental  retarda0on  in  humans  10/29/15 54

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Results •  uc248  knockout  :    

-­‐Expected  Phenotype:    Male  reproduc0ve  abnormality,  severe  dental  malforma0on  -­‐Observed  Phenotype:    Normal  reproduc0ve  capability  (Table  4),  normal  den00on  

•  uc467  knockout:  -­‐Expected  Phenotype:    Perinatal  mortality,  small  brain,  male  sexual  reproduc0ve  abnormality  -­‐Observed  Phenotype:    Normal  brain,  normal  reproduc0ve  capability  (Table  4),  normal  survival  (Table  2)  

•  uc329  knockout:  -­‐Expected  Phenotype:    Wilms  tumor,  WAGR  syndrome,  other  kidney  abnormality,  eye  abnormali0es  -­‐Observed  Phenotype:    ~2%  unilateral  renal  agenesis  (compare  to  0.5%  in  wt),  normal  eyes    

Table  2  (Expect  1:2:1  Ra0o)  

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•  Loss of highly conserved regulatory regions leads to insignificant (if any) phenotype

•  Maybe there is phenotype outside lab or over time •  Regulatory element redundancy probable •  The idea that highly conserved non-coding regions are

hotspots for developmental enhancers is not being challenged but it raises the question…

What prevents sequence change?

Summary #2

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Deep  phenotyping  can  reveal  defects  from  enhancer  dele0ons  

10/29/15 57 Acanasio  et  al…Pennacchio,  Visel  (2013)  Science  342:1241006    

Predict  cranio-­‐facial  enhancers  by  P300  ChIP-­‐seq.  Delete  candidate  enhancers.  Look  for  phenotypes  by  morphome0c  analysis.    

Genomics  of  Gene  Regula0on:  Predic0ng  and  tes0ng  CRMs  

•  Conserva0on  and  pacerns  of  alignments  in  noncoding  regions  can  be  used  to  predict  CRMs  –  Miss  lineage  specific  func0ons,  turnover  

•  Biochemical  features  associated  with  cis-­‐regulatory  modules  can  be  used  to  predict  CRMs  –  May  over-­‐call  CRMs  –  TF  occupancy  alone  does  not  necessarily  mean  that  the  DNA  is  ac0vely  

involved  in  regula0on.  •  Start  with  epigene0c  features,  and  use  evolu0onary  pacerns  to  

discern  history  and  predict  func0ons  –  Some  genes  have  conserved  expression  pacerns,  others  differ  between  

species  –  Conserva0on  of  TF  occupancy:  Pleiotropic  func0ons,  core  func0ons  –  Lineage-­‐specific  TF  occupancy:  Adap0ve  func0ons  –  Sequence  conserved  but  func0on  co-­‐opted  (exapted)  to  different  

func0on  in  one  species  

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Genomics  of  Gene  Regula0on:  Integra0on  and  Assays  

•  Individual  features  can  be  good  predictors,  but  they  tend  to  point  to  similar  regions    –  EP300,  0ssue-­‐specific  TFs,  H3K4me1,  H3K27ac  –  Simple  intersec0ons  do  not  increase  power  very  much  

•  Integra0on  of  features  by  unsupervised  machine-­‐learning  can  reveal  frequently  occurring  (and  important)  states  

•  Supervised  machine-­‐learning  (e.g.  EnhancerFinder)  does  a  good  job  of  finding  the  enhancers  it  was  trained  to  find:  developmental  enhancers  

•  Significant  progress  in  ramping  up  the  scale  of  gain-­‐of-­‐func0on  assays  for  enhancers  

•  Loss-­‐of-­‐func0on  assays  can  be  defini0ve  –  Facilitated  by  new  genome  edi0ng  technology  (CRISPR-­‐Cas9)  –  Some0mes  show  no  phenotype  for  strong  gain-­‐of-­‐func0on  enhancers  

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