Diet appears to have an effect on an organism’s physiological condition at all stages of life. Although the metabolic needs of brain development, particularly dendritic and axon growth, are generally recognised, little is known about how different foods impact this process.
The Graduate School of Biostudies at Kyoto University showed that by employing the correct models, researchers may explore the molecular basis of the regulatory systems driving nutrient-dependent neuronal growth.
“One such model is the Drosophila C4da — or class IV dendritic arborization — neuron located in the fruit flies’ larvae,” says lead author Yukako Hattori.
The dendrites of C4da neurons — located between the epidermis and body wall muscles — sense noxious thermal, mechanical, and light stimuli, subsequently transmitting information to the central nervous system to trigger avoidance behaviours.
“The growth of these dendrites is controlled by the environment in unexpected ways and becomes more complex. That is, a poor, low-yeast diet causes hyperarborization of dendrites,” adds first author Yasutetsu Kanaoka.
The scientists discovered that the hyperarborization phenotype was induced by a combined shortage in vitamins, metal ions, and cholesterol, rather than by low quantities of amino acids (typical yeast nutrition).
This deficit causes the body wall muscle to produce more Wingless signalling molecules. Wingless stimulates a protein called Akt, which increases the complex branching of dendrites once it is absorbed by C4da neurons.
“While this excess growth of C4da neurons despite a nutrient-poor environment is counterintuitive, we were further intrigued by those neurons becoming less responsive to the noxious light stimuli,” reflects Tadashi Uemura.
“Our study raises the possibility that nutrient-dependent development of somatosensory neurons plays a role in optimizing a trade-off between searching for high-nutrient foods and escaping from noxious environmental threats.”
Using cell type-specific knockdown systems — an established method to inhibit specific gene functions in a cell-specific manner — the team identified the inter-organ signalling that regulates the hyperarborization phenotype.
“By focusing on the mechanism by which nutritional information is transmitted from the intestine to the muscle, we may unravel the molecular mystery linking food and health.”