Most neurological and neurodevelopmental disorders are sex-biased in incidence or severity. To understand why one sex may be vulnerable to a disease, it is important to understand brain development in both sexes. Mood, cognition, and other processes are regulated by estrogen receptor (ER) ? neurons. Female have increased number of ER? neurons in the hypothalamus, compared to males. This is an example of a sex difference in neurochemical phenotype, the most common type of sex difference in the brain. Despite this, little is known on the mechanisms controlling their development. Our research suggests that epigenetic mechanisms underlie sex differences in neurochemical phenotype that may contribute to sex biases in disease. Inhibiting DNA methylation in the brains of newborn mice reduces sex differences in ER? in the preoptic area (POA) and the ventrolateral area of the ventromedial hypothalamus (VMHvl) at weaning. We recently reported that DNA methyltransferases (Dnmts; which add methyl marks) and ten eleven translocases (Tets; which remove methyl marks), peak shortly after birth in both sexes in the hypothalamus. Additionally, females have higher expression of Dnmts, while males have higher expression of Tets during this period. This suggests that DNA methylation and hydroxymethylation are dynamic and sex- biased during neonatal brain development. Interestingly, both sexes have an equally high number of ER? cells in the VMHvl at birth, but only in males, it decreases 50% by weaning. This proposal will test the hypothesis that ER? cells in males, but not females, accumulate DNA methylation marks during postnatal development which establishes the sex difference. The F99 phase will test 1) whether sub-populations of ER? cells with functional roles are sensitive to neonatal inhibition of DNA methylation using single-molecule fluorescent in situ hybridization and 2) whether specific sub-populations down-regulate ER? expression across development (Aim 2a). Lastly, using methylated and hydroxymethylated DNA immunoprecipitation sequencing, it will test the hypotheses that there are global sex differences and developmental changes in the epigenome, and specifically, that the ER? promoter in males has increased levels of DNA methylation compared to females (Aim 2b). The proposed study will help the candidate, Laura Cortes, achieve her goal of becoming a tenure-track professor at an R1 institution. This proposal will provide training in cutting-edge techniques, such as sm-FISH and epigenomic sequencing, to investigate how DNA methylation regulates neurochemical phenotype in both sexes. The Neuroscience Institute at Georgia State University is an ideal environment given the 1) access to the expertise of reputed neuroendocrinologists and state-of-the-art tools, 2) collaborative intra-departmental and inter-institutional atmosphere, and 3) the plethora of career development opportunities. Completion of the training plan described in this proposal will ensure the development of a well-rounded and successful scientist capable of transitioning into an independent investigator.

Public Health Relevance

The last stages of neuronal development involve specialization into specific cell ?fates?, and a current goal in neuroscience is to understand what leads to cell diversity. This proposal will examine the role of DNA methylation in sexual differentiation of neurochemical phenotype providing a potential mechanism by which cell identity is determined in the male and female brain. This work will contribute to understanding brain development in both sexes, an important endeavor given that many developmental and neuropsychiatric disorders are sex-biased.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Project #
1F99NS120531-01
Application #
10148128
Study Section
Special Emphasis Panel (ZNS1)
Program Officer
Jones, Michelle
Project Start
2020-12-15
Project End
2022-07-30
Budget Start
2020-12-15
Budget End
Support Year
1
Fiscal Year
2021
Total Cost
Indirect Cost
Name
Georgia State University
Department
Neurosciences
Type
Schools of Arts and Sciences
DUNS #
837322494
City
Atlanta
State
GA
Country
United States
Zip Code
30302