Genes Regulated By Hox Proteins
Hox genes act at many levels within developmental gene hierarchies: at the "executive" level they regulate genes that in turn regulate large networks of other genes (like the gene pathway that forms an appendage). They also directly regulate what are called realisator genes or effector genes that act at the bottom of such hierarchies to ultimately form the tissues, structures, and organs of each segment. Segmentation involves such processes as morphogenesis (differentiation of precursor cells into their terminal specialized cells), the tight association of groups of cells with similar fates, the sculpting of structures and segment boundaries via programmed cell death, and the movement of cells from where they are first born to where they will ultimately function, so it is not surprising that the target genes of Hox genes promote cell division, cell adhesion, apoptosis, and cell migration.
Organism | Target gene | Normal function of target gene | Regulated by |
---|---|---|---|
Drosophila | distal-less | activates gene pathway for limb formation | ULTRABITHORAX
(represses distal-less) |
distal-less | activates gene pathway for limb formation | ABDOMINAL-A
(represses distal-less) |
|
decapentaplegic | triggers cell shape changes in the gut that are
required for normal visceral morphology |
ULTRABITHORAX
(activates decapentaplegic) |
|
reaper | Apoptosis: localized cell death creates the segmental
boundary between the maxilla and mandible of the head |
DEFORMED
(activates reaper) |
|
dapentaplegic | prevents the above cell changes in more posterior
positions |
ABDOMINAL-B
(repress decapentaplegic) |
|
Mouse | EphA7 | Cell adhesion: causes tight association of cells in
distal limb that will form digit, carpal and tarsal bones |
HOX-A13
(activates EphA7) |
Cdkn1a | Cell cycle: differentiation of myelomonocyte cells into
monocytes (white blood cells), with cell cycle arrest |
Hox-A10
(activates Cdkn1a) |
Read more about this topic: Hox Gene
Famous quotes containing the words genes, regulated and/or proteins:
“Whether you want it or not,
your genes have a political past,
your skin a political tone.
your eyes a political color.
...
you walk with political steps
on political ground.”
—Wislawa Szymborska (b. 1923)
“Accidents will occur in the best regulated families; and in families not regulated by that pervading influence which sanctifies while it enhances theaI would say, in short, by the influence of Woman, in the lofty character of Wife, they may be expected with confidence, and must be borne with philosophy.”
—Charles Dickens (18121870)
“Civilization means food and literature all round. Beefsteaks and fiction magazines for all. First-class proteins for the body, fourth-class love-stories for the spirit.”
—Aldous Huxley (18941963)