Determining the effects of genetic variation and early life stress on the regulation of the galanin gene in fat and alcohol selection.

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Overindulgence in high calorie nutrients, which include fat and alcohol, has had a major effect on the health of the UK population where 67% of males and 57% of females are classed as overweight. Because obesity is linked to type 2 diabetes and cardiovascular disease we need to find the causes of this calorie overconsumption and a major source of the calories consumed by the UK population come in the form of fat and alcohol. In addition to cardiovascular disease and cancer, excessive alcohol consumption is also linked to liver cirrhosis and pancreatitis. Many of us are susceptible to over consume fat and alcohol as a result of differences in our DNA but there is also evidence that environmental factors such as early life stress also play a role. However, we still know very little about the mechanisms that influence our intake of fat and alcohol and how these mechanisms are affected by genetic variation and environment. Important clues have emerged. For example, a small neuropeptide, called galanin is expressed in a region of the brain called the hypothalamus that controls fat and alcohol intake. Removal of the gene which encodes galanin reduces fat and alcohol intake and decreases weight gain. A critical aspect of the function of galanin is that it should be expressed in the correct cells, in the correct amount and in response to the correct stimuli. However, nothing was known about the mechanisms controlling the production of galanin in the hypothalamus or how differences in the regions of DNA that control this expression might affect fat and alcohol intake. We first discovered a DNA switch sequence that was an excellent candidate for the undiscovered switch sequence that controls galanin in the hypothalamus. We then found that sequence changes within this switch that exist within the human population, and were linked to alcohol abuse, increased the strength of this switch in the hypothalamus. We also found epigenetic changes within the switch, called DNA methylation, that were altered by stress and seemed to also change the strength of the switch. We hypothesise that these sequence changes and methylation changes within the GAL gene switch work together to alter the production of galanin in the hypothalamus and to influence fat and alcohol intake. To address this hypothesis we used a remarkable new method called CRISPr genome editing to quickly and efficiently delete the switch from the genome. We will initially determine the effects of removing the switch on galanin production in the hypothalamus and determine its effects on fat and alcohol selection. We will use CRISPr technology again to reproduce known human sequence changes within the switch (a process known as humanisation) to model their effects on galanin production and fat and alcohol intake. We will then use these "humanised" models to determine the effects of early life stress on the methylation of the switch sequence and how this methylation affects its function. Using this revolutionary CRISPr technology we will determine how changes that occur naturally in the human population, as a result of genetics or environment, affect our fat and alcohol intake. Considering the huge problem of obesity and excessive alcohol intake in our society these studies will open avenues for not only understanding the role of genetics and environment in excess fat and alcohol intake but will also provide novel opportunities for reducing susceptibility to obesity by controlling excess calorie intake in the human population.