engrailed is a gene involved in many aspects of multicellular development. First known for its role in arthropod embryological development, working in consort with the Hox genes, engrailed has been found to be important in other areas of development. It has also been found to direct development in other taxa, for example: humans.
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Protein
engrailed (en) encodes the homeodomain-containing transcription factor protein Engrailed. Homologous Engrailed proteins are found in a diversity of organisms. When expressed in the ectoderm, engrailed is involved in the production of skeletal material.[1] engrailed, or genes with very similar sequences, are found in all bilaterian animals.[1] It has been observed to express in the repeated units of arthropods, molluscs, onychophora, annelids, echinoderms and amphioxus.[1] However its ancestral role is probably not in controlling segmentation, but rather in the production of armour - which has been secondarily lost in many lineages.[1]
Arthropods
In the model organism Drosophila melanogaster engrailed acts as a segment-polarity gene in early embryonic development. It is initially expressed in stage 10-11 of development in 14 isolated bands of cells along the embryo's anterior-posterior axis. The cells expressing engrailed define the anterior most region of each parasegment. Once proper segments form, engrailed expressing cells are found in the posterior-most region of each segment.[2]
engrailed homologs have also been found in many other arthropod species including: grasshoppers, milkweed bugs, centipedes, beetles, and others.
However, the ancestral role of engrailed was not in marking segmentation: it does not fulfill this role in Onychophora.[1]
Molluscs
In molluscs, engrailed is associated with shell formation, but is also expressed in organs of shell-less cephalopods including the tentacles and funnel.[3]
Neurological Development
engrailed plays a number of crucial roles in brain development across many species. Some of these include determining the hindbrain/midbrain border and aiding in neuronal axon guidance.[4]
References
- ^ a b c d e Jacobs, D. K. (2000). "Molluscan engrailed expression, serial organization, and shell evolution". Evolution & Development 2: 340–347. doi:.
- ^ Sanson, B. (2001). Generating patterns from fields of cells. EMBO reports 2(12):1083-1088
- ^ doi:10.1007/s00427-007-0147-2
This citation will be automatically completed in the next few minutes. You can jump the queue or expand by hand - ^ Morgan, R (2006). Engrailed: Complexity and economy of a multi-functional transcription factor. FEBS Letters 580(11):2531-3
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