From the WashU School of Medicine News…
Scientists at Washington University School of Medicine in St. Louis have identified a previously unknown route for cellular fuel delivery, a finding that could shed light on the process of aging and the chronic diseases that often accompany it.
With age, cells gradually lose their ability to take in and process fuel. A cell that can’t fill its fuel tank, so to speak, can’t perform its proper functions. Researchers are interested in finding ways to boost the energy supply of aging cells in an effort to stave off the detrimental effects of the inevitable passage of time.
A key element of any cell’s fuel supply chain is a molecule called nicotinamide adenine dinucleotide (NAD). Past work has shown that NAD levels in tissues throughout the body decrease with age. One way cells manufacture NAD begins with a precursor molecule called nicotinamide mononucleotide (NMN), which is found naturally in foods such as edamame, broccoli, cabbage, cucumber and avocado. But how NMN gets into cells to be processed into NAD has long been a mystery.
In a new study, scientists led by Shin-ichiro Imai, MD, PhD, a professor of developmental biology, have identified a protein responsible for transporting NMN directly into cells, where it can be used for cellular fuel production. Not only does this protein move NMN into cells, it does so rapidly.
The study is published Jan. 7 in the inaugural issue of the journal Nature Metabolism.
Imai and his team long suspected there was a direct route for NMN to get into cells, simply because they had measured the speed with which NMN made the journey from the gut into the bloodstream and then into tissues throughout the body. In mice, that journey happens in a matter of minutes. The researchers felt there wasn’t time for complex biochemical reactions that might convert NMN into another form that could be taken up by cells.
“To achieve such fast uptake of NMN into the tissues, we speculated that there must be a specific NMN transporter that moves NMN directly into cells, even though no one had ever seen such a thing,” Imai said.
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