Poor Maternal Nutrition during Gestation Alters Muscle Gene Expression in Fetal Offspring

Fetal muscle development is a complex process which can be affected by maternal diet. However, the mechanisms by which this occurs are not well known. We hypothesized that fetal development would result in temporal changes of key myogenic regulatory factors, and that under- and over-feeding ewes during gestation would alter the transcriptome profile of fetal muscle tissue. To test this hypothesis, pregnant Western White-faced ewes were individually housed and fed 100% (control-fed, n = 11), 60% (restricted-fed, n = 11), or 140% (over-fed, n = 10) of NRC requirements for TDN beginning at d 30.2 ± 0.2 of gestation. Ewes were euthanized at d 90 (n = 11) and d 135 (n = 10) of gestation, or allowed to undergo parturition and lambs euthanized at within 24 h of birth (n = 11) and male offspring LM tissue was collected (n = 3 to 4 per treatment per time point). Offspring from control-, restricted- and over-fed ewes are referred to as CON, RES and OVER, respectively. RNA was isolated from LM tissue, libraries prepared, and sequenced (Illumina NextSeq500). Data were aligned to the Ovis aries reference annotation using STAR aligner, and differentially expressed genes were identified using Ht-seq and DEseq2. The average number of raw reads was 26,065,509 with 85% mapability to the reference annotation. Main effect of diet was observed [q ≤ 0.05; (RES vs. CON; 2 genes upregulated, 5 genes downregulated), (OVER vs. CON; 3 genes upregulated, 9 genes downregulated), and (OVER vs. RES; 2 genes upregulated, 2 genes downregulated)]. This included genes involved in cell signaling (Endoplasmic reticulum to nucleus signaling 2, SH2 Domain Containing 6), regulation of inflammation (C-C motif chemokine 2 ligand, Pentraxin-related protein) and epigenetic regulation (Histone Deacetylase 10, Histone H1.3). Similarly, a main effect of time (q ≤ 0.05) was observed with significant differences for d 135 vs. d 90 (137 genes upregulated, 172 genes downregulated), birth vs. d 90 (693 genes upregulated, 2378 genes downregulated), and birth vs. d 135 (80 genes upregulated, 291 genes downregulated). No significant interactions of diet by day of gestation were observed (q ≥ 0.2). Pathway analysis using PANTHER determined that genes involved in metabolic, cellular, and developmental processes were most affected over time. In conclusion, poor maternal nutrition may alter offspring muscle development through genes involved in cell signaling, inflammation, and epigenetic regulation.