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XB-ART-45398
Int J Dev Biol 2012 Jan 01;565:357-62. doi: 10.1387/ijdb.120009nd.
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Involvement of the eukaryotic initiation factor 6 and kermit2/gipc2 in Xenopus laevis pronephros formation.

Tussellino M , De Marco N , Campanella C , Carotenuto R .


Abstract
The translation initiation factor Eif6 has been implicated as a regulator of ribosome assembly, selective mRNA translation and apoptosis. Many of these activities depend upon the phosphorylation of eif6 Serine 235 by protein kinase C (PKC). Eif6-60S is probably part of the RNA-induced silencing complex (RISC). eif6 over-expression in Xenopus embryos causes aberrant eye development. kermit2/gipc2 morphants have an eye phenotype similar to that of the eif6 overexpressors. Eye formation is regulated by insulin growth factor (IGF) signalling. eif6 interacts with the IGF receptor (IGFR) and kermit2/gipc2, which also binds to igfr. eif6 over-expression in Xenopus causes also the formation of antero-ventral oedema, suggesting a malfunction of the excretory system. Here we evaluated the pronephros phenotype. The oedema grows into the nephrocoel, expanding its boundary and is accompanied by a strong reduction of the pronephros. The three main components of the pronephros are severely impaired in eif6 over-expressors, while are not affected in eif6 morphants. Conversely, gipc2 depletion induces the oedema phenotype and reduction of the pronephros, while gipc2 overexpression does not. p110*, a constitutively active p110 subunit of the PI3 kinase partially recovers the oedema phenotype. We also determined that PKC-dependent phosphorylation of Ser235 in eif6 is not required to produce defective pronephroi. These results indicate that the levels of eif6 are highly regulated during development and instrumental for proper morphogenesis of the pronephros. Moreover, it appears that for proper pronephros development the gipc2 level should be kept within or over the physiological range and that the oedema phenotype is partly due to the inhibition of IGF signalling.

PubMed ID: 22689378
Article link: Int J Dev Biol


Species referenced: Xenopus laevis
Genes referenced: cdh16 clcnkb eif6 gipc1 gipc2 ins kcne1 lhx1 myod1 nphs1 slc5a9
Morpholinos: eif6 MO1 gipc2 MO1


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