Gene regulation in Drosophila melanogaster

Genetic studiesOne of the best understood developmental systems13,600 genes

Axis determinationSignaling pathwayTranscriptional and translational regulation

The genetics of axis specification in Drosophila

Chang-Gung UniversityDr. Li-Mei Pai

The Chapter 9 of Developmental Biology by Scott Gilbert, 7th edition

Targeted ectopic expression of the Eyeless gene--induce eyes to develop in locations such as legs and antennae

Closely related genes initiate the development program for the same organ in animals separate by 500 million years of evolution

Life cycle of Drosophila 4 stages: embryo, larva, pupa, adult

Culture condition: 250C and 60% humidity

Science, 297, 2270-2275, 2002

Comparison of Larval and Adult Segmentation in Drosophila

Body patterning of fly

One cell to an organism

Laser Confocal Micrographs of Stained Chromatin Showing Superficial Cleavage in a Drosophila Embryo

Early development of Drosophila

Rapid division8 mins/division9 divisions

13 divisions

Single cell

asynchronous

Formation of the Cellular Blastoderm in Drosophila

Transgenic flies

One single epithelial layer –all tissuesMesoderm—muscle, connective tissuesEndoderm---midgut (foregut and hidgut-Ectoderm)Ectoderm---nervous tissue and epidermis

Gastrulation

Figure 9.5(1) Gastrulation in Drosophila

Figure 9.5(2) Gastrulation in Drosophila

Germ band extention

Figure 9.5(3) Gastrulation in Drosophila

Germ band retraction

The sequential expression of different sets of genes establishes the body plan along the anterior-posterior axis

Localized mRNA and ProteinsTranslated after fertilization—

Positional information to activate zygotic genes

parasegment

Pattern in the segment

Segment identities

Temporal sequence

The sequential expression of different sets of genes establishes the body plan along the anterior-posterior axis

The sequential expression of different sets of genes establishes the body plan along the anterior-posterior axis

Maternal effect genes—( do not damage mother)preformed mRNA and proteins in the egg

Zygotic genes—embryo nuclei

Three classes of mutants affect the anterior, posterior, and terminal development

head and thoracic

abdominal

acron and telson

Polarization of the body axes during oogenesis

each egg chamber: 3 types of cellsOocyte with nucleus (germinal vesicle-GV)Connected to 15 nurse cells }---germ-lineSurrounded by a monolayer of about 1000 somatic follicle cells

Polarization of the body axes during oogenesis

Polarization of the body axes during oogenesis

Three independent Genetic Pathways Interact to Form theAnterior-Posterior Axis of the Drosophila Embryo

Three independent Genetic Pathways Interact to Form the Anterior-Posterior Axis of the Drosophila Embryo

Specifying the Anterior-Posterior Axis of the Drosophila Embryo During Oogenesis

Specifying the Anterior-Posterior Axis of the Drosophila Embryo During Oogenesis

Protein kinase A orients the microtubules

Gradient of Bicoid Protein in the Early Drosophila Embryo

bicoid mRNA in the anterior tip of the embryo3’ untranslated regionExuperantia and Swallow proteins link bicoid to dynein ATPasesFertilization-receives a longer polyadenylate tail-trnaslated

Gradient of Bicoid Protein in the Early Drosophila Embryo

concentrated in the nuclei

Experiments Demonstrating that the bicoid Gene Encodes the Morphogen Responsible for Head Structures in Drosophila

Gradient of Caudal Protein in the Syncitial Blastoderm of aWild-type Drosophila Embryo

Activates genes responsible for the invagination of the midgutBicoid binds to its 3’UTR and prevents its translation

Anterior-Posterior Pattern Generation by the DrosophilaMaternal Effect Genes

Control of hunchback mRNA Translation by Nanos Protein

Anterior-Posterior Pattern Generation by the DrosophilaMaternal Effect Genes

Bicoid stimulates hunchback transcription

All transcription factors

maternal

zygotic

Formation of the Unsegmented Extremities by torso Signaling

torso-receptor tyrosine kinaseDistinction A/P is bicoid

Groucho –transcriptional inhibitortailless, huckebein

Model of Drosophila Anterior-Posterior Pattern Formation

Maternal effect genes

Zygotic genesSyncytial blastoderm

Cellular blastoderm

Conversion of Maternal Protein Gradients into Zygotic Gap Gene Expression

Transcription factor

Conversion of Maternal Protein Gradients into Zygotic Gap Gene Expression

Model of Drosophila Anterior-Posterior Pattern Formation

Maternal effect genes

Zygotic genesSyncytial blastoderm

Cellular blastoderm

Specific Promoter Regions of the even-skipped (eve) Gene Control Specific Transcription Bands in the Embryo

Division cycle 13

the 2nd parasegmentthe expression of eve

Bicoid and hb activate eveKruppel and giant repress eve

Hypothesis for the formation of the Second Stripe of Transcription from the even-skipped Gene

Hypothesis for the Formation of the Second Stripe of Transcriptionfrom the even-skipped Gene

6 sites

3 sites5 sites

3 sites

Cis-regulatory enhancer elementsTrans-regulatory gap gene proteins

Model for the Transcription of the Segment Polarity Genesengrailed and wingless (wg)

Reinforce the PSCell-cell signaling

Model for the Transcription of the Segment Polarity Genesengrailed and wingless (wg)

Model for the Transcription of the Segment Polarity Genesengrailed and wingless (wg)

gradients

Homeotic Gene Expression in Drosophila

thoracic

head

3rd thoracic

abdomen

Homeotic complex

A Four-winged Fruit Fly Constructed by Putting Together Three Mutations in cis Regulators of the Ultrabithorax Gene

Homeotic mutants

Ultrabithorax gene is deletedT3 to T2 transformation

Effect of Mutations Affecting the Distribution of the Dorsal Protein

Translocation of Dorsal Protein into Ventral, but not Lateral or Dorsal, Nuclei

The Generation of Dorsal-Ventral Polarity in Drosophila

Conserved Pathway for Regulating Nuclear Transport of TranscriptionFactors in Drosophila and Mammals

Zygotic genes pattern the early embryoDorsal protein activates twist and snail represses dpp,zen, tolloid

Rhomboid----neuroectodermRepressed by snail (not most ventral)

Binding sites for dorsal protein in their regulatory regions

Model for the subdivision of the dorso-ventral axis into different regions by the gradient in nuclear dorsal protein

Patterns of Gene Expression During Drosophila Mesoderm Development

Eileen E. M. Furlong, Erik C. Andersen, Brian Null,Kevin P. White, Matthew P. ScottScience, 293, 1629, 2001

Goals of ExperimentsSuggestions, opinions

Subdivision of the Dorsal-Ventral Axis by the Gradient ofDorsal Protein in the Nuclei

TABLE 1. Cancer-related genes in Drosophila melanogaster

Fly genes homologous to mammalian oncogenes

Fly genesarmadilloD. AblD. AktaurorahomothoraxDcblDcrkcicyclin DRasD.retsmoothened smoSrc42A, Src64Bstringtrithorax ALL-1D.TCFtorpedo

Mammalian gene or productb-cateninc-ablAktaurora 1, aurora 2, AIM-1 Meis1c-cblc-crkGli1, Gli2, Gli3cyclin D/ PRAD1RasretSmoc-srccdc25All1TCFc-erbB-2

TABLE 1. Cancer-related genes in Drosophila melanogaster

Fly genes homologous to mammalian tumor suppressor genes

Fly genesD-APCcaudalfrazzledgigashaywireklumpfussmedeamei-41MerlinD.NF1patchedPP2A-29BD.PTEND.p16RbfspellcheckerD.XpaD.XPD

Mammalian gene or productAPCCDX2DCCTSC2ERCC3WT-1DPC4ATMNF2NF1ptchPPP2RIBPTEN/ MMACp16(INK4a)/ MTS1pRBhMSH2XPAXPD/ERCC2

FLP(flippase)/FRT(target site) system-mitotic recombination

Large tumor suppressor (Lats), human gene rescue fly mutant

Climbing test: Negative geotactic response, monitor aging-related changes

A30P—day 23 to 45

elav-GAL4/

UAS--synuclein

Premature loss of climbing abilityIn -synuclein transgenic flies

A Drosophila model of Parkinson’s disease Nature(2000) , 404, 394-398

Retinal degeneration

Exam retinal pseudopupil: sensitive to disruption in the normal architecture

Generation of second site modifiers and pharmacological manipulations to modify this degeneration

Gmr-GAL4/+ Gmr-GAL4/+UAS-wt -synuclein

Steroid Control of Longevity in Drosophila melanogaster

Anne F. Simon, Cindy Shih, Antha Mack, Seymour Benzer*

Science, Vol. 299, P1407-1410, 2003

Extension of lifespan in an ecdysone receptor heterozygous mutant

Information : a. Books

The making of a fly (Peter Lawrence; Blackwell Scientific, 1992). The development of Drosophila melanogaster (ed. Bate & Martinez-Arias; Cold Spring Harbor Press, 1993) Fly pushing: The Theory and Practice in Drosophila genetics (Ralph Greenspan ; Cold Spring Harbor Press, 1997)

Drosophila: A practical approach (ed. DB Roberts; IRL Press, 1998).

Drosophila Protocols (ed. Sullivan, Ashburner, and Hawley; Cold Spring Harbor Press, 2000)

The genome of Drosophila melanogaster (by Dan L. Lindsley and Georgianna G. Zimm; Academia Press,1992)

b. The Flybase

http://flybase.bio.indiana.edu http://flybase.nhri.org.tw http://www.bdgp.org/ http://homophila.sdsc.edu/