Activities of the protein kinases STK, PI3K, MEK, and ERK are required for the development of the head organizer in Hydra magnipapillata

Arvizu, Fernando; Aguilera, A.; Salgado, Luis M.

doi:10.1111/j.1432-0436.2006.00078.x

Cited by 17 publications

(17 citation statements)

References 33 publications

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“…Both showed that activation of STK (Cardenas et al 2000;Cardenas and Salgado 2003;Manuel et al 2006;Arvizu et al 2006), GSK3 (Broun et al 2005), PKC, Pi3K, ERK 1-2 (Manuel et al 2006;Arvizu et al 2006), MAPK and RSK (Kaloulis et al 2004;Chera et al 2011) are indeed necessary over the first hours following bisection (see…”

Section: Activation Of Stk Pi3k Erk and Mapk Pathways During Head Bmentioning

confidence: 99%

“…The study of these kinases allowed the group of Luis Salgado to investigate two interesting aspects of head organizing activities in Hydra : The first question was to discriminate between the formation and the maintenance phases of the head organizer during regeneration: the STK, Pi3K, ERK 1-2 and MAPK pathways are clearly involved in the formation of the head organizer and not for the maintenance of its activity as when these inhibitors are given several hours after bisection, they loose their inhibitory effect, proving that when organizer activity is set up, the activity of these kinases is no longer necessary (Arvizu et al 2006). Indeed after decapitation Apigenin, LY294002 and PD98059 that inhibit ERK 1-2, PI3K and MEK respectively need to be added within the first 6 hours to show an effect on head regeneration (Manuel et al 2006;Arvizu et al 2006).…”

Section: % Inhibited After Decapitationmentioning

confidence: 99%

“…Indeed after decapitation Apigenin, LY294002 and PD98059 that inhibit ERK 1-2, PI3K and MEK respectively need to be added within the first 6 hours to show an effect on head regeneration (Manuel et al 2006;Arvizu et al 2006). Similarly a short pulse of U0126 given for 90 minutes before and after mid-gastric bisection suffice to inhibit injury-induced apoptosis, phosphorylation of the CREB transcription factor and head regeneration (Kaloulis et al 2004;Chera et al 2011).…”

Section: % Inhibited After Decapitationmentioning

confidence: 99%

“…By contrast after decapitation (80% body length) head injuryinduced apoptosis and apoptosis-induced compensatory proliferation are not observed (Galliot and Chera 2010) and Wnt3 seems to be directly upregulated in the epithelial cells (Lengfeld et al 2009). Among the pharmacological inhibitors that affect the early phase of head regeneration but not foot regeneration (see Table-2), only U0126 was tested after mid-gastric bisection (Cardenas and Salgado 2003;Kaloulis et al 2004;Arvizu et al 2006;Manuel et al 2006;Chera et al 2011). …”

Section: % Inhibited After Decapitationmentioning

confidence: 99%

“…When heads from intact animals treated for 48 hours were grafted, a fully efficient organizer activity was recorded, similar to that obtained with heads from untreated polyps, indicating that exposure to a single kinase inhibitor does not affect the organizer activity in homeostatic conditions. By contrast when the apical tips of decapitated polyps exposed to one or the other kinase inhibitors for 48 hours were grafted, the organizer activity was totally missing, demonstrating that the STK, Pi3K, ERK 1-2 and MEK kinases are necessary for the formation of the head organizer after decapitation (Arvizu et al 2006). However in most of these studies, the role of these signaling pathways was investigated exclusively after decapitation and not after mid-gastric bisection (Table 2).…”

Section: % Inhibited After Decapitationmentioning

confidence: 99%

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Injury-induced asymmetric cell death as a driving force for head regeneration in Hydra

Galliot

2012

Dev Genes Evol

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The freshwater Hydra polyp provides a unique model system to decipher the mechanisms underlying adult regeneration. Indeed a single cut initiates two distinct regenerative processes, foot regeneration on one side, head regeneration on the other side, the latter relying on the rapid formation of a local head organizer. Two aspects are discussed here, the asymmetric cellular remodeling induced by mid-gastric bisection and the signaling events that trigger head organizer formation. In head-regenerating tips (but not in foot ones) a wave of cell death takes place immediately, leading the apoptotic cells to transiently release Wnt3 and activate the β-catenin pathway in the neighboring cycling cells to push them through mitosis. This process, which mimics the apoptosis-induced compensatory proliferation process deciphered in Drosophila larvae regenerating their discs likely corresponds to an evolutionarily-conserved mechanism, also at work in Xenopus tadpoles regenerating their tale or mice regenerating their skin or liver. How is this process generated in Hydra? Several studies pointed to the necessary activation of the ERK 1-2 and MAPK pathways during early head regeneration and indeed ERK 1-2 inhibition or RSK, CREB, CBP knockdown prevent injury-induced apoptosis and head regeneration. The current scenario involves an asymmetric activation of the MAPK/CREB pathway to trigger injury-induced apoptosis in the interstitial cells, and, in the epithelial cells a CREB/CBP-dependent transcriptional activation of early genes essential for head organizing activity as wnt3, HyBra1, prdl-a. The question now is how bisection in the rather uniform central region of the polyp can generate this immediately asymmetric signaling.

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