Summary: New research shows that the taste or smell of food activates specific sensory neurons, which in turn produce an insulin-like factor that can shorten lifespan by suppressing an anti-aging protein.
Source: POSTECH.
Animals detect environmental cues such as temperature and the taste or smell of food using specialized nerve cells called sensory neurons. These neurons do more than relay sensory information: in many organisms, sensory neurons influence aging. The tiny roundworm Caenorhabditis elegans has been a key model for uncovering how sensory perception affects longevity.
Sensory neuron dysfunction has previously been linked to lifespan extension through activation of the FOXO family of transcription factors. FOXO proteins trigger protective gene programs that help repair cellular damage and preserve tissue function. Until now, however, the pathway that connects sensory neurons to systemic control of FOXO activity across an organism has been unclear.
Researchers at Pohang University of Science and Technology (POSTECH), led by Professor Seung-Jae Lee with PhD candidate Murat Artan, proposed that food-related smells or tastes influence sensory neurons to release hormone-like signals that regulate aging. In a study published as the cover article in Genes & Development, the team shows that food cues acting on sensory neurons elevate expression of an insulin-like peptide, INS-6. This sensory neuron–derived INS-6 acts as a neuroendocrine signal that decreases DAF-16/FOXO activity in distant tissues, thereby shortening lifespan.
Using C. elegans as their experimental system, the researchers found that exposure to food-derived cues increases ins-6 expression, and that higher INS-6 levels correlate with reduced activity of DAF-16/FOXO and a shorter life span. Conversely, impairing the activity of the specific sensory neurons that detect food reduced ins-6 expression and allowed FOXO to activate protective gene programs, extending longevity. These findings clarify a mechanistic link between environmental perception and whole-organism aging: sensory neurons convert external cues into hormonal signals that shape systemic aging pathways.
To test whether activation of food-sensing neurons alone is sufficient to drive this effect, the team used optogenetics to selectively stimulate a pair of sensory neurons with blue light. Optogenetic activation raised ins-6 expression and shortened lifespan even in the absence of actual food taste or smell. This experiment demonstrates that direct neural activation triggers the neuroendocrine cascade, identifying the sensory neurons and INS-6 as key mediators that translate sensory input into lifespan modulation.
These results are notable because similar processes are observed across species. In humans, simply perceiving food can raise circulating insulin levels, and many fundamental aging-related pathways are conserved between C. elegans and mammals. The authors therefore suggest that sensory perception and neuroendocrine responses — for example, sensory neuron–driven release of insulin-like factors — may represent an evolutionarily conserved mechanism linking environmental cues to organismal aging.
Source: YunMee Jung – POSTECH
Image Source: This NeuroscienceNews.com image is in the public domain.
Original Research: Abstract for “Food-derived sensory cues modulate longevity via distinct neuroendocrine insulin-like peptides” by Murat Artan, Dae-Eun Jeong, Dongyeop Lee, Young-Il Kim, Heehwa G. Son, Zahabiya Husain, Jinmahn Kim, Ozlem Altintas, Kyuhyung Kim, Joy Alcedo, and Seung-Jae V. Lee in Genes & Development. Published online April 28, 2016.
POSTECH. “Sensory Neurons Modulate Aging Hormone.” NeuroscienceNews. May 26, 2016.
Abstract
Food-derived sensory cues modulate longevity via distinct neuroendocrine insulin-like peptides
Environmental changes affect organismal aging by influencing regulatory systems such as sensory neurons, which have a documented role in lifespan control across species. The mechanisms by which sensory neurons coordinate aging in response to external signals have been unclear. This study demonstrates that a specific subset of sensory neurons in Caenorhabditis elegans shortens life span by selectively increasing the expression of an insulin-like peptide, INS-6. Exposure to food-derived cues or optogenetic activation of these sensory neurons elevates ins-6 expression and shortens life span. INS-6 conveys longevity signals to nonneuronal tissues by reducing the activity of the transcription factor DAF-16/FOXO. Together, these results define a mechanism by which environmental sensory cues regulate aging rates through modulation of distinct sensory neurons and neuroendocrine insulin-like peptides.
“Food-derived sensory cues modulate longevity via distinct neuroendocrine insulin-like peptides” by Murat Artan et al., Genes & Development. Published online April 28, 2016.