Low FoxO expression inDrosophilasomatosensory neurons protects dendrite growth under nutrient restriction

Abstract

17During prolonged nutrient restriction, developing animals redistribute vital nutrients to favor brain 18 growth at the expense of other organs. In Drosophila, such brain sparing relies on a glia-derived growth 19 factor to sustain proliferation of neural stem cells. However, whether other aspects of neural 20 development are also spared under nutrient restriction is unknown. Here we show that dynamically 21 growing somatosensory neurons in the Drosophila peripheral nervous system exhibit organ sparing at 22 the level of arbor growth: Under nutrient stress, sensory dendrites preferentially grow as compared to 23 neighboring non-neural tissues, resulting in dendrite overgrowth. Underlying this neuronal nutrient-24 insensitivity is the lower expression of the stress sensor FoxO in neurons. Consequently, nutrient 25 restriction suppresses Tor signaling less and does not induce autophagy in neurons. Preferential dendrite 26 growth is functional desirable because it results in heightened animal responses to sensory stimuli, 27 indicative of a potential survival advantage under environmental challenges.28

Cell type-specific modulation of healthspan by Forkhead family transcription factors in the nervous system

“…Specifically, our results place neurons alongside differentiated intestinal cells (21) as cell types in which FKH, rather than FOXO, is sufficient to mediate prolongevity effects. Notably, these results are in agreement with other recent studies pointing to the limited expression of FOXO in Drosophila neurons compared with other cell types (54). Our results also place glial cells alongside the fat body (24) and some gut cell populations (20) as Drosophila cell types in which FOXO can mediate similar effects.…”