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

Reference	BB/N017544/1
Principal Investigator / Supervisor	Dr Alasdair MacKenzie
Co-Investigators / Co-Supervisors	Dr Scott Davidson, Professor Mirela Delibegovic, Dr Chris Murgatroyd
Institution	University of Aberdeen
Department	Sch of Medicine, Medical Sci & Nutrition
Funding type	Research
Value (£)	418,914
Status	Completed
Type	Research Grant
Start date	07/11/2016
End date	06/11/2019
Duration	36 months

Abstract

We will determine the effects of genetics and epigenetics on the mechanisms that control galanin gene (GAL) expression in the paraventricular nucleus (PVN) where galanin controls fat and alcohol intake. Excess fat and alcohol contribute to obesity that is a risk factor in diabetes and cardiovascular disease. Alcohol abuse is also linked to cirrhosis and pancreatitis. We need to know; 1. What happens to the expression of galanin and fat and alcohol intake when you remove the regulatory elements that control GAL expression in PVN. 2. What are the effects of genetic variation on these regulatory elements and in fat and alcohol intake. 3. How are these regulatory elements affected by epigenetic modification as a result of early life stress. We identified a regulatory element (GAL5.1) that is active in GAL expressing cells of the PVN. Polymorphisms within GAL5.1, associated with alcohol abuse, have a significant effect on its activity. Early life stress was shown to increase GAL mRNA in the PVN and led to changes in GAL5.1 methylation. We hypothesise that GAL5.1 is important in the regulation of GAL in the PVN and that polymorphisms and epigenetic modification influence the expression of GAL that, in turn, influence fat and alcohol intake. We have used CRISPr technologies to knock out GAL5.1 from the mouse genome and will use GAL mRNA expression analysis and fat/alcohol intake tests to determine the effects of GAL5.1 deletion. Humanisation of GAL5.1 in mice using CRISPr technologies to reproduce both human polymorphisms will permit a comparison of alleles on GAL expression and alcohol/fat intake. Humanisation will also permit an analysis of the effects of early life stress on the methylation of the human GAL5.1 in-vivo whose CpG content and distribution differs from mouse. The unique studies described in this proposal will revolutionise our understanding of the roles of gene regulation in nutrition and will have important ramifications for obesity research.

Summary

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.

Impact Summary

Our research will contribute fundamental new knowledge relating to the mechanisms regulating fat and alcohol intake with a range of potential beneficiaries in the academic, commercial and public sectors. To maximise engagement with these stakeholders and deliver the widest possible impact from our findings, we will pursue the following specific objectives: 1: Impact through training. The current proposal will permit the further training of a highly skilled and motivated post-doctoral scientist; Scott Davidson, in the role of genetics and epigenetics in the control of fat/alcohol intake. Dr. Davidson will receive training in new and powerful technologies such as CAS9/CRISPr genome editing, that Dr. MacKenzie has adopted and mastered in Aberdeen, epigenetic analysis of early life stress, genomics, mRNA expression analysis and in-vivo physiological and metabolic studies. This training will allow Dr. Davidson to eventually progress as an independent researcher within the UK. 2: Expansion of current public engagement activities. An immediate impact of this project is its opportunity to raise public awareness and understanding of the role of gene regulation in the control of appetite and nutrient selection. Additionally, engaging with school children is vital, not only for educating in the benefits of a healthy diet and the role of genetics and environment in its control but also for inspiring the next generation of researchers in nutrition. Throughout the project, we will engage with the public in the following ways: (a)To maximise the availability of our research, we will publish the results from this project in high-impact journals with Open Access Compliant policies. We will also promote the findings of our studies on our respective University web pages and in the national and international press. (b)We will continue to make use of the University of Aberdeen Press Office, as well as the BBSRC media services, to disseminate our findings as widely as possible to the general public. (c)At least once a year we will continue our outreach activities with school children . (d)Once a year we will engage the public through public seminars and science festivals. (e)We will continue to use the University of Aberdeen Public Engagement with Science Unit (PERU) to keep us updated on additional public engagement opportunities to expand our current activities. 3: Establish formal links with clinical science . Our published work the identification of functional variation within the GAL5.1 enhancer has inspired at least two major patient based association analysis that established a significant association between GAL5.1 haplotypes and increased alcohol consumption in certain populations. We will continue to engage the clinical community by; (i) Publishing our results in a timely manner and continuing to chair and deliver presentations at national and international conferences attended by both scientists and clinicians. (ii) Seek formal collaborations with clinicians to explore potential clinical applications of the planned research. 4: Commercial exploitation of research outcomes. We have had success in collaborating with industrial partners as reflected by our current partnership with GW Pharmaceuticals. We will continue to seek further industrial collaborations and have organised meetings with representatives from Eli Lilly, Alder pharmaceuticals and Pharmnovo who I have invited to speak at Neuropeptides-2015 (a conference organised by AM in Sept 2015) and who have an interest in discussing the implications of genetic and epigenetic variation on appetite and patient drug responses. We will also seek assistance of University bodies such as the Kosterlitz Centre to seek further links with academic and industrial partners. We will also work with the Research and Innovation Department at The University of Aberdeen who will review opportunities for commercialisation throughout the project.

Committee	Research Committee A (Animal disease, health and welfare)
Research Topics	Diet and Health, Neuroscience and Behaviour
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	X – not Funded via a specific Funding Scheme

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