The engrailed gene is a segment polarity gene in Drosophila melanogaster that plays several important roles during development. It defines the posterior region of each embryonic parasegment, establishing anterior-posterior polarity. The engrailed gene also helps pattern the brain by defining borders between regions and guiding neuronal axon growth. Comparisons of engrailed DNA and protein sequences across species show it is conserved and related genes can be found in vertebrates as well.

1. Engrailed Gene
Drosophila melanogaster

2. Background
Kim, C. (Artist). (2008). Transcription Factor. Duke University Howard Hughes Undergraduate Programs. Retrieved April 14, 2013, from
http://howardhughes.trinity.duke.edu

3. Arthropod Embryological
Development
• Engrailed acts as a segment-polarity gene in early
embryological development of Drosophila
• It defines polarity along the anterior-posterior axis
– Creates 14 parasegments
• Defines anterior-posterior boundary within each
parasegment
– Engrailed is found in the posterior region of each
parasegment
• Has a role in brain development
– Defines mid-/hindbrain border
– Guides neuronal axons

4. Segment Polarity Gene
• Engrailed gene is a segment polarity gene
• Engrailed Protein
Schmidt, J. W. (Artist). (2004). Fig. 6 Pair rule. Wikimedia Commons.
Retrieved April 14, 2013, from
http://en.wikipedia.org/wiki/Drosophila_embryogenesis#Additional_se
gmentation_genes
Schmidt, J. W. (Artist). (2004). Figure 7.
Reciprocal signaling between Wingless and Hedgehog producing cells.
Wikimedia Commons. Retrieved April 14, 2013, from
http://en.wikipedia.org/wiki/
Drosophila_embryogenesis#Additional_segmentation_genes

5. Anterior-Posterior Axis Patterning in
Drosophila
• One of the main types of genes involved is
segmentation genes, including engrailed
• Embryological stripes are the result of 14
segments with engrailed expressed in the
posterior region of each segment

6. Function
• Brain Development
• Axon guidance
• First known for its role in
arthropod embryological
development
(2001-2002). MedEdCenter. Retrieved April 14, 2013,
from http://www.edoctoronline.com

7. Nucleotide Sequence Analysis
Figure 1. Engrailed Gene DNA Sequence Analysis Comparison Among Fly, Norway Rat, Zebrafish, and Western Clawed Frog.
Florence Corpet. (2013). MultiAlin result page. In MultiAlin. Retrieved April 9, 2013, from http://multalin.toulouse.inra.fr/multalin/cgi-bin/multalin.pl

8. DNA Phylogeny
Figure 2. Phylogenetic Tree of Engrailed Gene.
(2013). Evry, France; Réseau National des. Génopoles. Retrieved April 9, 2013,
from http://phylogeny.fr

9. Protein Sequence Analysis
Figure 3. Engrailed Gene’s Protein Sequence Analysis Comparison of Fly, House Mouse, Human, Norway Rat, Zebrafish, Western Clawed Frog, Purple
Sea-Urchin, Nematode, and Domestic Chicken.
Florence Corpet. (2013). MultiAlin result page. In MultiAlin. Retrieved April 9, 2013, from http://multalin.toulouse.inra.fr/multalin/cgi-bin/multalin.pl

10. Protein Sequence Phylogeny
Figure 4. Phylogenetic Tree of Engrailed Gene’s Protein.
(2013). Evry, France; Réseau National des. Génopoles. Retrieved April 9, 2013, from
http://phylogeny.fr

11. Research
• Kornberg et al.
examined homozygous
engrailed mutants and
heterozygous (mosaic
cell) mutants
– Homozygous died with
fused, abnormal
segments
– Mosaic cell suffer
abnormalities in the
posterior segments
• Hidalgo examined
processes regulated by
engrailed during
morphogenesis of the
fly wing
– Found that engrailed has
more than just a
patterning function

12. Bibliography
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Brody, Thomas B. "Interactive Fly, Drosophila." Interactive Fly, Drosophila. Society for
Developmental Biology, 5 Dec. 1997. Web. 12 Apr. 2013.
Thomas Kornberg, Inga Sidén, Patrick O'Farrell, Michael Simon, The engrailed locus of
drosophila: In situ localization of transcripts reveals compartment-specific expression, Cell,
Volume 40, Issue 1, January 1985, Pages 45-53, ISSN 0092-8674, 10.1016/00928674(85)90307-1. (http://www.sciencedirect.com/science/article/pii/0092867485903071)
(2013). Evry, France; Réseau National des. Génopoles. Retrieved April 9, 2013, from
http://phylogeny.fr
Florence Corpet. (2013). MultiAlin result page. In MultiAlin. Retrieved April 9, 2013, from
http://multalin.toulouse.inra.fr/multalin/cgi-bin/multalin.pl
Kim, C. (Artist). (2008). Transcription Factor. Duke University Howard Hughes Undergraduate
Programs. Retrieved April 14, 2013, from http://howardhughes.trinity.duke.edu
Schmidt, J. W. (Artist). (2004). Fig. 6 Pair rule. Wikimedia Commons. Retrieved April 14, 2013,
from
Schmidt, J. W. (Artist). (2004). Figure 7. Reciprocal signaling between Wingless and
Hedgehog producing cells. Wikimedia Commons. Retrieved April 14, 2013, from
http://en.wikipedia.org/wiki/Drosophila_embryogenesis#Additional_segmentation_genes
(2001-2002). MedEdCenter. Retrieved April 14, 2013, from http://www.edoctoronline.com