Talk:Zone of polarizing activity

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ZPA and hedgehog

It looks like someone has altered hedgehog to Sonic Hedgehog in this article. KathyfromNC (talk) 17:49, 2 July 2016 (UTC)[reply]

No I'm wrong. The gene is hedgehog for flies and sonic hedgehog for chickens. KathyfromNC (talk) 17:55, 2 July 2016 (UTC)[reply]

Removed content

Formation

Re-entered removed text - needs proper formatting before re-adding. Also to note only one link is necessary. --Iztwoz (talk) 11:49, 31 January 2018 (UTC)[reply]

The Hox genes, which define features along the anterior-posterior axis of a developing organism, dictate at which points along the axis that limb buds will form.[1] Though limbs emerge at different locations in different species, their positions always correlate with the level of Hox gene expression along the anterior-posterior axis.[1] All limb buds must rely on other signaling factors to obtain their forelimb or hindlimb identity as well; Hox gene expression influences expression of T-box proteins that, in turn, dictate limb identity for certain organisms.[2]

In turn, the activation of T-box proteins activates signaling cascades that involve the Wnt signaling pathway and FGF signals.[2] Before limb development begins, T-box proteins initiate FGF10 expression in the proliferating mesenchymal cells of the lateral plate mesoderm, which form the limb bud mesoderm.[2] WNT2B and WNT8C stabilize this FGF10 expression in the forelimb and hindlimb, respectively.[3][4] This FGF10 expression stimulates WNT3 expression in the above ectodermal cells – resulting in formation of the apical ectodermal ridge (AER) as well as inducing FGF8 expression.[5] The FGF8 secreted by the AER acts to keep the cells of the limb mesenchyme in a mitotically active state and sustains their production of FGF10.[5] This positive feedback loop between the limb mesenchymal cells and the AER maintains the continued growth and development of the entire limb.[6] In addition to limb outgrowth, AER leads to the formation of the ZPA.[2]

References

  1. ^ a b Iimura, T; Pourquié, O (2007). "Hox genes in time and space during vertebrate body formation". Development, Growth & Differentiation. 49 (4): 265–75. doi:10.1111/j.1440-169X.2007.00928.x. PMID 17501904.
  2. ^ a b c d Tickle2015
  3. ^ Ng, J. K; Kawakami, Y; Büscher, D; Raya, A; Itoh, T; Koth, C. M; Rodríguez Esteban, C; Rodríguez-León, J; Garrity, D. M; Fishman, M. C; Izpisúa Belmonte, J. C (2002). "The limb identity gene Tbx5 promotes limb initiation by interacting with Wnt2b and Fgf10". Development (Cambridge, England). 129 (22): 5161–70. PMID 12399308.
  4. ^ Kawakami, Y; Capdevila, J; Büscher, D; Itoh, T; Rodríguez Esteban, C; Izpisúa Belmonte, J. C (2001). "WNT signals control FGF-dependent limb initiation and AER induction in the chick embryo". Cell. 104 (6): 891–900. PMID 11290326.
  5. ^ a b Ohuchi, H; Nakagawa, T; Yamamoto, A; Araga, A; Ohata, T; Ishimaru, Y; Yoshioka, H; Kuwana, T; Nohno, T; Yamasaki, M; Itoh, N; Noji, S (1997). "The mesenchymal factor, FGF10, initiates and maintains the outgrowth of the chick limb bud through interaction with FGF8, an apical ectodermal factor". Development (Cambridge, England). 124 (11): 2235–44. PMID 9187149.
  6. ^ Rodriguez-Esteban, C; Tsukui, T; Yonei, S; Magallon, J; Tamura, K; Izpisua Belmonte, J. C (1999). "The T-box genes Tbx4 and Tbx5 regulate limb outgrowth and identity". Nature. 398 (6730): 814–8. Bibcode:1999Natur.398..814R. doi:10.1038/19769. PMID 10235264.
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