Next-generation sequencing identifies polyunsaturated fatty acid responsive genes in the juvenile rat cerebellum

Authors: Mehus, Aaron; Dickey, Aaron; Smith, Timothy - Tim; Yeater, Kathleen; Picklo, Matthew

Submitted to: Nutrients
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/20/2019
Publication Date: 2/15/2019
Citation: Mehus, A.A., Dickey, A.M., Smith, T.P., Yeater, K.M., Picklo, M.J. 2019. Next-generation sequencing identifies polyunsaturated fatty acid responsive genes in the juvenile rat cerebellum. Nutrients. https://doi.org/10.3390/nu11020407.
DOI: https://doi.org/10.3390/nu11020407

Interpretive Summary: Childhood undernutrition is a worldwide problem. Several lines of evidence indicate the importance of dietary polyunsaturated fatty acids (PUFA) in proper brain development. In humans, brain accumulation of PUFA begins prenatally and continues until the second year after birth. During this period of infant brain development, PUFAs incorporate into cellular membranes, regulate gene expression, and facilitate growth of brain cells. In animals, antenatal and postnatal juvenile dietary deficiencies in n-3 PUFA are associated with learning, behavioral, and visual impairments. Given the importance of PUFA in juvenile brain health, we wanted to identify the degree to which dietary n-3 PUFA deficiency changes gene expression within the cerebellum, a developing part of the brain that coordinates motor function, of young rats. Our hypothesis was that a diet deficient in n-3 PUFA would result in modifications to juvenile cerebellar gene expression compared to rats with adequate n-3 PUFA in their diets. Using state-of-the-art RNA sequencing (RNAseq) technology, we demonstrated that the expression of Nr4a3, a gene involved with cell protection and learning, was elevated over 2-fold in the cerebellum of juvenile rats eating the n-3 PUFA deficient diet. These data, derived through ARS team research, show that reducing dietary content of n-3 PUFA in young animals is capable of changing brain gene expression in the cerebellum.

Technical Abstract: Dietary n-3 polyunsaturated fatty acids (PUFA) influence postnatal brain growth and development. However, little data exist regarding the impacts of dietary n-3 PUFA in juvenile animals post weaning, a time of rapid growth. We tested the hypothesis that depleting dietary n-3 PUFA would result in modifications to the cerebellar transcriptome of juvenile rats. Three week old male rats (an age that roughly corresponds to an eleven month old child) were fed diets consisting of either a-linolenic acid (ALA; 18:3n-3) sufficient soybean oil (SO) or ALA-deficient, corn oil (CO) for four weeks. Fatty acids (FAs) in the cerebellum were analyzed and revealed a 4-fold increase in n-6 docosapentaenoic acid (DPA; 22:5n-6), an increase in arachidonic acid (AA; 20:4n-6), but no decrease in docosahexaenoic acid (DHA; 22:6n-3), in animals fed CO versus SO. Transcript abundance was then characterized to identify differentially expressed genes (DEGs) between the two diets. Upper quartile (UQ) scaling and transcripts per million (TPM) data normalization identified 100 and 107 DEGs, respectively. Comparison of DEGs from the two normalization methods identified 70 genes that overlapped, with 90% having abundance differences less than 2-fold. Nr4a3, a transcriptional activator that plays roles in neuroprotection and learning, was elevated over 2-fold from the CO diet. These data indicate that expression of Nr4a3 in the juvenile rat cerebellum is responsive to dietary n-3 PUFA but additional studies are needed clarify the neurodevelopmental relationships between n-3 PUFA and Nr4a3 and the resulting impacts.