Session: SSASAS: Breeding and Genetics

370 - The Potential Use of DNA Methylation Patterns from Peripheral Blood Leukocytes as a Surrogate for Stress Axis Tissues in Mature Brahman Cows

Friday, July 16, 2021

5:00 PM – 5:15 PM EST

Location: Kentucky International Convention Center (KICC), M105 & 106

Presenting Author(s)

Emilie C. Baker

PhD Student
Texas A&M University
Elgin, Texas

PDF Slides and Audio

Author(s)

Audrey L. Earnhardt, MS

PhD Student
Texas A&M University; Texas A&M AgriLife Research, College Station
College Station, Texas
KC

Kubra Z. Cilkiz

PhD Student
Texas A&M University
College Station, Texas
BL

Brittni P. Littlejohn

Assistant Professor
University of Arkansas
Fayetteville, Arkansas
HC

Haley C. Collins

PhD Student
Texas A&M University
College Station, Texas
NG

Noushin Ghaffari

Assistant Professor
Prairie View A&M University
Prairie View, Texas
PR

Penny K. Riggs, Ph.D

Associate Professor
Texas A&M University
College Station, Texas
CL

Charles R. Long, Ph.D.

Resident Director
Texas A&M AgriLife Research, Overton
Overton, Texas
TW

Thomas H. Welsh, Jr.

Professor
Texas A&M University; Texas A&M AgriLife Research, College Station
College Station, Texas
RR

Ron D. Randel, Ph.D.

Professor
Texas A&M AgriLife Research, Overton
Overton, Texas
DR

David G. Riley, PhD

Professor
Texas A&M University
College Station, Texas

DNA methylation (DNAm) patterns are tissue specific and aid in tissue specific gene expression changes. The use of DNAm patterns from peripheral blood leukocytes (PBL) as a surrogate for patterns in other tissues is common, especially in longitudinal studies when sampling of tissues is not plausible. Thus, the objective of this study was to investigate the suitability of using DNAm patterns of PBL as a surrogate for the DNAm patterns in neuroendocrine tissues responsible for stress responses and energy metabolism. Samples from the paraventricular region of the hypothalamus, anterior pituitary gland, adrenal cortex, and the adrenal medulla were harvested from 5-yr-old Brahman cows (n = 8) and DNA was extracted from each sample. Methylation was assessed using reduced representation sodium bisulfite sequencing and differentially methylated regions (DMR) between the PBL DNA and tissue DNA were identified using EdgeR from Bioconductor, R. Analysis revealed over 15,000 DMRs located within promoter regions of genes in each tissue, with the majority of the sites having increased methylation in the PBL (Table 1). To further evaluate the use of PBL DNA as a surrogate, Pearson correlation values were calculated for genes (n = 20) pertinent to each respective tissue using the mean methylation of the specific gene in the PBL and in the tissue (Table 2). Three correlations were significant (P ≤ 0.05), two of which were negative. The sizable differences indicate that DNA methylation patterns from PBL do not compare well to patterns from hypothalamic, pituitary, adrenal cortex, and adrenal medulla tissues from 5-yr-old Brahman cows. This is especially the case for the majority of the specific genes examined in this study. Whether DNAm in the surrogate PBL will shift in a direction similar to that of specific tissues of Brahman cows exposed to stressful stimuli during developmental periods remains to be determined.