Dosage Compensation and Gene Expression of the X Chromosome in Sheep. Issue 1 (1st January 2019)

• Record Type: Journal Article
• Authors: Duan, Jingyue (Ellie); Flock, Kaleigh; Jue, Nathanial; Zhang, Mingyuan; Jones, Amanda; Seesi, Sahar Al; Mandoiu, Ion; Pillai, Sambhu; Hoffman, Maria; O'Neill, Rachel; Zinn, Steven; Govoni, Kristen; Reed, Sarah; Jiang, Hesheng; Jiang, Zongliang (Carl); Tian, Xiuchun (Cindy)
• Is Part Of: G3. Volume 9:Issue 1(2019)
• Page Start: 305
• Page End: 314
• Publication Date: 2019-01-01
• Subjects: Ohno's hypothesis -- X chromosome upregulation -- Maternal nutrition -- Ovine; Genetics -- Research -- Periodicals; Genomics -- Periodicals; Genetics; Genomics; Genes; Genetics -- Research; Genomics; Electronic journals; Periodical; Periodicals; Fulltext; Internet Resources; Periodicals; 572.8
• DOI: 10.1534/g3.118.200815
• Languages: English
• ISSNs: 2160-1836

Abstract

Abstract: Ohno's hypothesis predicts that the expression of the single X chromosome in males needs compensatory upregulation to balance its dosage with that of the diploid autosomes. Additionally, X chromosome inactivation ensures that quadruple expression of the two X chromosomes is avoided in females. These mechanisms have been actively studied in mice and humans but lag behind in domestic species. Using RNA sequencing data, we analyzed the X chromosome upregulation in sheep fetal tissues from day 135 of gestation under control, over or restricted maternal diets (100%, 140% and 60% of National Research Council Total Digestible Nutrients), and in conceptuses, juvenile, and adult somatic tissues. By computing the mean expression ratio of all X-linked genes to all autosomal genes (X:A), we found that all samples displayed some levels of X chromosome upregulation. The degrees of X upregulation were not significant (P-value = 0.74) between ovine females and males in the same somatic tissues. Brain, however, displayed complete X upregulation. Interestingly, the male and female reproduction-related tissues exhibited divergent X dosage upregulation. Moreover, expression upregulation of the X chromosome in fetal tissues was not affected by maternal diets. Maternal nutrition, however, did change expression levels of several X-linked genes, such as sex determination genes SOX3 and NR0B1 . In summary, our results showed that X chromosome upregulation occurred in nearly all sheep somatic tissues analyzed, thus support Ohno's hypothesis in a new species. However, the levels of upregulation differed by different subgroups of genes such as those that are house-keeping and "dosage-sensitive".