Zerknüllt Explained

Uniprot:P09089
Organism:Drosophila melanogaster
Zerknüllt 1
Symbol:zen
Uniprot:P09090
Organism:Drosophila melanogaster
Zerknüllt 2
Symbol:zen2

Zerknüllt (zen, German for "crumpled") is a gene in the Antennapedia complex of Drosophila (fruit flies) and other insects, where it operates very differently from the canonical Hox genes in the same gene cluster. Comparison of Hox genes between species showed that the Zerknüllt gene evolved from one of the standard Hox genes (the 'paralogy group 3' Hox gene) in insects through accumulating many amino acid changes, changing expression pattern, losing ancestral function and gaining a new function.[1] [2]

Zerknüllt codes for a homeoprotein regulates aspects of early embryogenesis in insects. Unlike the canonical Hox genes which are expressed in precise zones along the anteroposterior (head to tail) body axis, zerknüllt expression is restricted along the dorsoventral (back to belly) body axis. Expression of Zerknüllt is repressed in the ventral part of the embryo by a protein called Dorsal, and activated in the dorsal part of the embryo by the TGF beta signaling pathway.[3] The cells which activate the Zerknüllt develop into extraembryonic tissues which surround the developing insect embryo.[4]

Zerknüllt has been found to undergo a number of gene duplications in certain insect lineages. For example, in the beetle Tribolium castaneum zen duplicated to yield zen and zen2; in many flies, including Drosophila, zen duplicated to give zen, zen2 and the even more divergent Bicoid gene.[5] [6] Large expansions of zen through gene duplication have also been observed within Lepidoptera. In this group, zen has duplicated at least four times resulting in the emergence of the additional divergent 'Special homeobox' (Shx) genes, named ShxA, ShxB, ShxC and ShxD.[7] The original zen gene is still present. In some lepidopteran species, such as the Domesticated Silkmoth Bombyx mori, even greater numbers of duplications of zen occurred, with 12 Shx loci annotated along with zen.[8]

See also

Notes and References

  1. Falciani F, Hausdorf B, Schröder R, Akam M, Tautz D, Denell R, Brown S . Class 3 Hox genes in insects and the origin of zen . Proceedings of the National Academy of Sciences of the United States of America . 93 . 16 . 8479–84 . August 1996 . 8710895 . 10.1073/pnas.93.16.8479 . 38697 . 1996PNAS...93.8479F . free .
  2. Panfilio KA, Liu PZ, Akam M, Kaufman TC . Oncopeltus fasciatus zen is essential for serosal tissue function in katatrepsis . Developmental Biology . 292 . 1 . 226–43 . April 2006 . 16460723 . 10.1016/j.ydbio.2005.12.028 . free .
  3. Rushlow C, Colosimo PF, Lin MC, Xu M, Kirov N . Transcriptional regulation of the Drosophila gene zen by competing Smad and Brinker inputs . Genes & Development . 15 . 3 . 340–51 . February 2001 . 11159914 . 10.1101/gad.861401 . 312624 . free .
  4. Rushlow C, Frasch M, Doyle H, Levine M . Maternal regulation of zerknüllt: a homoeobox gene controlling differentiation of dorsal tissues in Drosophila . Nature . 330 . 6148 . 583–6 . December 1987 . 2891036 . 10.1038/330583a0 . 1987Natur.330..583R . 4334188 .
  5. Brown SJ, Fellers JP, Shippy TD, Richardson EA, Maxwell M, Stuart JJ, Denell RE . Sequence of the Tribolium castaneum homeotic complex: the region corresponding to the Drosophila melanogaster antennapedia complex . Genetics . 160 . 3 . 1067–74 . March 2002 . 10.1093/genetics/160.3.1067 . 11901122 . 1462024 .
  6. Negre B, Casillas S, Suzanne M, Sánchez-Herrero E, Akam M, Nefedov M, Barbadilla A, de Jong P, Ruiz A . 6 . Conservation of regulatory sequences and gene expression patterns in the disintegrating Drosophila Hox gene complex . Genome Research . 15 . 5 . 692–700 . May 2005 . 15867430 . 10.1101/gr.3468605 . 1088297 . free .
  7. Ferguson L, Marlétaz F, Carter JM, Taylor WR, Gibbs M, Breuker CJ, Holland PW . Ancient expansion of the hox cluster in lepidoptera generated four homeobox genes implicated in extra-embryonic tissue formation . PLOS Genetics . 10 . 10 . e1004698 . October 2014 . 25340822 . 10.1371/journal.pgen.1004698 . 4207634 . free .
  8. Chai CL, Zhang Z, Huang FF, Wang XY, Yu QY, Liu BB, Tian T, Xia QY, Lu C, Xiang ZH . 6 . A genomewide survey of homeobox genes and identification of novel structure of the Hox cluster in the silkworm, Bombyx mori . Insect Biochemistry and Molecular Biology . 38 . 12 . 1111–20 . December 2008 . 19280701 . 10.1016/j.ibmb.2008.06.008 . Special Issue on the Silkworm Genome .

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