Origens evolucionárias dos genes de controle dos cristalinos Pax6

sexta-feira, setembro 01, 2017

Evolutionary Origins of Pax6 Control of Crystallin Genes 

Ales Cvekl Yilin Zhao Rebecca McGreal Qing Xie Xun Gu Deyou Zheng

Genome Biology and Evolution, Volume 9, Issue 8, 1 August 2017, Pages 2075–2092, https://doi.org/10.1093/gbe/evx153

Published: 16 August 2017 Article history

Accepted: 14 August 2017

Source/Fonte: Osaka University


The birth of novel genes, including their cell-specific transcriptional control, is a major source of evolutionary innovation. The lens-preferred proteins, crystallins (vertebrates: α- and β/γ-crystallins), provide a gateway to study eye evolution. Diversity of crystallins was thought to originate from convergent evolution through multiple, independent formation of Pax6/PaxB-binding sites within the promoters of genes able to act as crystallins. Here, we propose that αB-crystallin arose from a duplication of small heat shock protein (Hspb1-like) gene accompanied by Pax6-site and heat shock element (HSE) formation, followed by another duplication to generate the αA-crystallin gene in which HSE was converted into another Pax6-binding site. The founding β/γ-crystallin gene arose from the ancestral Hspb1-like gene promoter inserted into a Ca2+-binding protein coding region, early in the cephalochordate/tunicate lineage. Likewise, an ancestral aldehyde dehydrogenase (Aldh) gene, through multiple gene duplications, expanded into a multigene family, with specific genes expressed in invertebrate lenses (Ω-crystallin/Aldh1a9) and both vertebrate lenses (η-crystallin/Aldh1a7 and Aldh3a1) and corneas (Aldh3a1). Collectively, the present data reconstruct the evolution of diverse crystallin gene families.

aldehyde dehydrogenase, crystallin, eye evolution, heat shock responsive element, lens, Pax6, small heat shock protein

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