en
Scientific article
Open access
English

Head regeneration in wild-type hydra requires de novo neurogenesis

Published inDevelopment, vol. 134, no. 6, p. 1191-1201
Publication date2007
Abstract

Because head regeneration occurs in nerve-free hydra mutants, neurogenesis was regarded as dispensable for this process. Here, in wild-type hydra, we tested the function of the ParaHox gsx homolog gene, cnox-2, which is a specific marker for bipotent neuronal progenitors, expressed in cycling interstitial cells that give rise to apical neurons and gastric nematoblasts (i.e. sensory mechanoreceptor precursors). cnox-2 RNAi silencing leads to a dramatic downregulation of hyZic, prdl-a, gsc and cnASH, whereas hyCOUP-TF is upregulated. cnox-2 indeed acts as an upstream regulator of the neuronal and nematocyte differentiation pathways, as cnox-2(-) hydra display a drastic reduction in apical neurons and gastric nematoblasts, a disorganized apical nervous system and a decreased body size. During head regeneration, the locally restricted de novo neurogenesis that precedes head formation is cnox-2 dependent: cnox-2 expression is induced in neuronal precursors and differentiating neurons that appear in the regenerating tip; cnox-2 RNAi silencing reduces this de novo neurogenesis and delays head formation. Similarly, the disappearance of cnox-2(+) cells in sf-1 mutants also correlates with head regeneration blockade. Hence in wild-type hydra, head regeneration requires the cnox-2 neurogenic function. When neurogenesis is missing, an alternative, slower and less efficient, head developmental program is possibly activated.

Keywords
  • Animals
  • Body Patterning/genetics
  • Cell Differentiation/genetics
  • Cell Proliferation
  • Down-Regulation
  • Gene Expression Regulation, Developmental
  • Head/physiology
  • Homeodomain Proteins/antagonists & inhibitors/genetics/physiology
  • Hydra/genetics/physiology
  • Nervous System/cytology/growth & development
  • RNA Interference
  • Regeneration/genetics
Citation (ISO format)
MILJKOVIC-LICINA, Marijana et al. Head regeneration in wild-type hydra requires de novo neurogenesis. In: Development, 2007, vol. 134, n° 6, p. 1191–1201. doi: 10.1242/dev.02804
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Article (Published version)
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Identifiers
ISSN of the journal0950-1991
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