The smell of food induces a variety of physiological processes in our body. Thus, the production of saliva and digestive enzymes is stimulated before the actual food intake in order to prepare the gastrointestinal tract for the upcoming digestive process. In a healthy organism, this coordination depends on a dynamic balance between formation and degradation of proteins (proteostasis). This plays an important role for recycling of cells and during the aging process. Scientists of the Hoppe lab now succeeded in demonstrating the influence of food odors on proteostasis. The experimental investigations were carried out in the roundworm Caenorhabditis elegans, a fundamental model organism of modern biomedical research. Two of the 358 neurons that form the nematode nervous system are part of the olfactory system and thus, important for odor perception. The researchers were able to uncover the influence of smelling on the physiology of the digestive tract by investigating the recycling of green fluorescent proteins in the intestine. The brighter the green fluorescent signal within the worms the more severe the accumulation of cellular waste; strongly correlating with defective protein degradation. The underlying processes are mediated by the regulatory microRNA molecule mir-71. mir-71 regulates the genetic program of olfactory neurons and, hereafter, degradation processes in the digestive tract. However, if this mechanism is blocked, not only cellular recycling processes are diminished, but also the animals’ lifespan - in other words, roundworms with a non-functional "sense of smell" live much shorter - a strong indication for its physiological significance. This novel mechanism is central for proper processing of odor signals and mediates adjustments in the intestinal cells. "We assume that in this way the organism coordinates food intake and effective degradation", commented first author Dr. Fabian Finger, who was recently awarded with the Klaus Liebrecht Prize of the UoC for his work.
"The impact of odors at the cellular level is a poorly investigated field," says Prof. Thorsten Hoppe. "It is well known that malfunctions in odor perception are associated with neurodegenerative diseases. We will further investigate the influence of the perception of odors on aging-associated disorders such as Alzheimer's or Parkinson's disease. "
Olfaction regulates organismal proteostasis and longevity via microRNA-dependent signalling
Fabian Finger, Franziska Ottens, Alexander Springhorn, Tanja Drexel, Lucie Proksch, Sophia Metz, Luisa Cochella und Thorsten Hoppe
Nature Metabolism, DOI: https://doi.org/10.1038/s42255-019-0033-z
Prof. Thorsten Hoppe
Principal Investigator, CECAD Cologne and Institute for Genetics
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