Developmental switches and gene regulatory networks in the most completely described animal, the nematode C. elegans

Transcription

1 Developmental switches and gene regulatory networks in the most completely described animal, the nematode. elegans Joel Rothman U Santa Barbara Generating developmental diversity: Symmetry breaking Dr. Joel Rothman, MD Biology, USB (KIP Bio Seminars 10/12/04) 1

2 Asymmetric cell division A B =. elegans genetics complete anatomy and development complete genome (100,258,171 bp) overnight gene knockouts (RNAi) conserved genetic toolkit Dr. Joel Rothman, MD Biology, USB (KIP Bio Seminars 10/12/04) 2

3 . elegans development Sir John Sulston 2002 Nobel Major cell types made by founder cells Dr. Joel Rothman, MD Biology, USB (KIP Bio Seminars 10/12/04) 3

4 he first symmetry break: A/P axis Ant Post Wallenfang, M.R. and Seydoux, G., 2000 stablishing A/P polarity after uenca et al., Develop. 130, 235 (2003) Dr. Joel Rothman, MD Biology, USB (KIP Bio Seminars 10/12/04) 4

5 Asymmetric first division AB P1 Asymmetric cell division = Dr. Joel Rothman, MD Biology, USB (KIP Bio Seminars 10/12/04) 5

6 formation of the. elegans endoderm mesoderm endoderm mesectoderm formation of the. elegans endoderm mesoderm mesectoderm gut Dr. Joel Rothman, MD Biology, USB (KIP Bio Seminars 10/12/04) 6

7 formation of the. elegans mesoderm endoderm mesectoderm pharynx, body muscle, somatic gonad, etc. formation of the. elegans endoderm mesoderm mesectoderm gut Dr. Joel Rothman, MD Biology, USB (KIP Bio Seminars 10/12/04) 7

8 MD-1/2 GAAs specify mesendoderm MD-1,2 maternal zygotic wild type fate fate med(-) (mesectoderm) Mesendoderm development P1 PAL-1 MDs GSK-3 MDs PAL-1 genes genes NDs genes NDs genes Dr. Joel Rothman, MD Biology, USB (KIP Bio Seminars 10/12/04) 8

9 ND-1/3 GAAs specify endoderm MD-1,2 ND-1,3 a p a gastrulation repression of fate wild type end-1/3(-) ND-1/3 specify endoderm MD-1,2 ND-1,3 fate wild type ubiquitous Dr. Joel Rothman, MD Biology, USB (KIP Bio Seminars 10/12/04) 9

10 ND-1/3 specify endoderm MD-1,2 W ND-1,3 L-2,7 ND-1::nR fate Shoichet, S.A., Malik,.H., Rothman, J.H., and Shivdasani, R.A. PNAS 97, 4076 (2000) L-2/7 GAAs control gut differentiation maternal wt MD-1,2 ND-1,3 L-2,7 elt-2/7( 2/7(-) differentiation gut structural proteins, enzymes Dr. Joel Rothman, MD Biology, USB (KIP Bio Seminars 10/12/04) 10

11 zygote properties of endoderm regulatory cascade MD-1,2 specification ND-1,3 L-2,7 differentiation fate zygote properties of endoderm regulatory cascade AB inducer MD-1,2 fate ND-1,3 Features 1. Redundancy (GAAs) 2. cell division cell cycle gastrulation repression of L-2,7 fate 3. dedicated functions Dr. Joel Rothman, MD Biology, USB (KIP Bio Seminars 10/12/04) 11

12 Asymmetric cell division = P2 induces fate P 2 fate fate Dr. Joel Rothman, MD Biology, USB (KIP Bio Seminars 10/12/04) 12

13 specification of and P 2 Wnt, MAPK MDs fate POP-1 rep NDs MDs NDs fate POP-1 act specification of and P 2 Wnt, MAPK MDs POP-1 rep NDs MDs NDs POP-1 act fate fate POP-1 1 HIGH POP-1 1 LOW Dr. Joel Rothman, MD Biology, USB (KIP Bio Seminars 10/12/04) 13

14 recursive POP-1 asymmetry A P High POP-1 Low POP-1 Lin et al. (1998) ell 92, dynamics of POP-1 HIGH LOW Dr. Joel Rothman, MD Biology, USB (KIP Bio Seminars 10/12/04) 14

15 what are the med-1,2 targets? med-1,2 med-1,2 pharynx, body muscle, somatic gonad, etc. intestine MD-1 1 binds a novel target site MD-1 - G A A G A A G A A G end-1 end-3 GAA factor MD-1 A H G A A R A G consensus A A Dr. Joel Rothman, MD Biology, USB (KIP Bio Seminars 10/12/04) 15

16 GAA sites are required for end-1 expression 4 GFP X GFP X GFP genomic search for MD targets query with Wormnhancer: [A A G A A ] [A A G A A ] N Dr. Joel Rothman, MD Biology, USB (KIP Bio Seminars 10/12/04) 16

17 putative MD targets A A G A A A A G A A N gene F F F35H8.7 ceh-20/f313.2 F58G ZK D1.2 ZK177.10, ZK A , B0303.8, 9 product end-1 end-3 wee-1.1 homeobox LAG-2-like Sox family (HMG) R1 unknown -box/unknown oxygen transport bhlh (2) unknown MD sites three classes of candidate MD targets sox-1::gfp hlh-25 ::GFP 2 tbx-35 ::GFP 4 wee-1.1 ::GFP 2 07D1.2 ::GFP 2 Dr. Joel Rothman, MD Biology, USB (KIP Bio Seminars 10/12/04) 17

18 the evolving gene regulatory network MD-1,2 POP-1 sox-1 end-1,3 wee D1.2 sox-1 end-1,3 wee D1.2 -Box bhlh -Box bhlh wnt-dependent repression the evolving gene regulatory network MD-1,2 POP-1 POP-1 sox-1 end-1,3 wee D1.2 -Box bhlh sox-1 end-1,3 wee D1.2 -Box bhlh Dr. Joel Rothman, MD Biology, USB (KIP Bio Seminars 10/12/04) 18

19 Sea urchin regulatory network Rothman Lab Dr. Joel Rothman, MD Biology, USB (KIP Bio Seminars 10/12/04) 19

20 ollaborators. Fukushige and Jim McGhee (algary) R. Shivdasani (Dana Farber) M. Meneghini and B. Bowerman (Oregon) B. Shraiman, Ruadhan O'Flanagan et al. (KIP, USB) Research Group Dr. Joel Rothman, MD Biology, USB (KIP Bio Seminars 10/12/04) 20

21 MDs, POP-1, ND-3, Ls Gina Broitman- Maduro Morris Maduro Keith Strohmaier Farzaneh Masoud Dr. Joel Rothman, MD Biology, USB (KIP Bio Seminars 10/12/04) 21