Next‐generation nutritional screening

Abstract

The biochemical identification of essential vitamins and minerals during the early 20th century led to major public health advances through treatment and prevention of deficiency diseases. Today, we face an epidemic of overnutrition. Chronic metabolic conditions such as obesity and diabetes are responsible for millions of deaths each year and constitute an enormous global health burden. Despite the major influence of diet on this epidemic, nutrition knowledge has not been applied as successfully as for vitamin and mineral deficiency diseases. In addition to vitamins and minerals, the foods we eat contain thousands of biologically active nutritional compounds that are managed at the cellular level by molecular networks which sense the cellular nutritional state and respond to maintain homeostasis. A key hub in these networks, and the focus of this project, is the endoplasmic reticulum (ER), a cellular organelle that is a broad sensor of nutritional and metabolic status. Impaired ER function is implicated in the development of obesity and diabetes, and improvement of ER function is a common therapeutic target that can potentially improve health in many tissues and disease states. Among its many functions, the ER is a major site for metabolism of lipids, a class of nutritional compounds that includes fatty acids and bile acids. Enzymes located on the ER membrane metabolize lipids from the diet, and also synthesize lipids de novo. While lipid synthesis at the ER has been widely studied, little is known about how the ER handles the many lipids from the diet, and how the response of the ER to dietary lipids impacts health. Without new tools to detect how cells sense and respond to nutritional compounds, we are unable to make continued progress in nutrition to reduce chronic metabolic conditions.The aim of this project is to create a novel cellular screening system to detect the effects of nutritional compounds. This project will focus on lipids, as they are rich in diversity and biology, and our lab is well‐equipped to study them. I will begin by curating a small collection of the predominant lipids in the human diet. These lipids are included in an existing collection of 688 lipids that our lab has established in collaboration with the Broad Institute for screening. In order to detect the cellular effects of lipids, I will focus on indicators of ER function. We have developed luminescent cellular reporters for real‐time monitoring of ER function in live cells. I will introduce these reporters into adipocytes, cells that manage systemic nutrient levels through storage and release of lipids. These reporter cells will be integrated into a microfluidic chip the size of a microscope slide. It will contain chambers, where we will seed cells expressing the ER reporters, and channels to flow culture medium and nutritional compounds to the cells. This system will enable high‐throughput screening of dietary lipids, continuous sampling of the culture medium for evaluation of the dynamic response of the ER, and co‐culture of related cell types, such as adipocytes and macrophages, to model cellular interactions.Support or Funding InformationWe acknowledge the generous support of the Sabri Ülker Food Research Foundation, Sabri Ülker Center, and Harvard Training Program in Nutritional Metabolism T32 training grant (4T32HD052961‐10).