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Loss of neurogenesis in aging Hydra

Fisher, Kathleen
Austad, Steven
Published in Developmental Neurobiology. 2019
Abstract In Hydra the nervous system is composed of neurons and mechano‐sensory cells that differentiate from interstitial stem cells, which also provide gland cells and germ cells. The adult nervous system is actively maintained through continuous de novo neurogenesis that occurs at two distinct paces, slow in intact animals and fast in regenerating ones. Surprisingly Hydra vulgaris survive the elimination of cycling interstitial cells and the subsequent loss of neurogenesis if force‐fed. By contrast, H. oligactis animals exposed to cold temperature undergo gametogenesis and a concomitant progressive loss of neurogenesis. In the cold‐sensitive strain Ho_CS, this loss irreversibly leads to aging and animal death. Within four weeks, Ho_CS animals lose their contractility, feeding response and reaction to light. Meanwhile, two positive regulators of neurogenesis, the homeoprotein prdl‐a and the neuropeptide Hym‐355, are no longer expressed, while the “old” RFamide‐expressing neurons persist. A comparative transcriptomic analysis performed in cold‐sensitive and cold‐resistant strains confirms the down‐regulation of classical neuronal markers during aging but also shows the up‐regulation of putative regulators of neurotransmission and neurogenesis such as AHR, FGFR, FoxJ3, Fral2, Jagged, Meis1, Notch, Otx1, TCF15. The switch of Fral2 expression from neurons to germ cells suggests that in aging animals, the neurogenic program active in interstitial stem cells is re‐routed to germ cells, preventing de novo neurogenesis and impacting animal survival.
Keywords Hydra nervous systemInterstitial stem cellsAdult de novo neurogenesisGametogenesisAgingHomeoprotein prdl-aNeuropeptide Hym-355Evolution of neurogenesis
PMID: 30912256
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Projects FNS: 31003A_149630, 31003_169930
NIH R01AG037962
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TOMCZYK, Szymon et al. Loss of neurogenesis in aging Hydra. In: Developmental Neurobiology, 2019. doi: 10.1002/dneu.22676 https://archive-ouverte.unige.ch/unige:115742

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Deposited on : 2019-04-04

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