Gene expression in sheep carotid arteries: major changes with maturational development

Abstract

Background: With development from immature fetus to near-term fetus, newborn, and adult, the cerebral vasculature undergoes a number of fundamental changes. Although the near-term fetus is prepared for a transition from an intra- to extra-uterine existence, this is not necessarily the case with the premature fetus, which is more susceptible to cerebrovascular dysregulation. In this study, we tested the hypothesis that the profound developmental and age-related differences in cerebral blood flow are associated with significant underlying changes in gene expression.

Methods: With the use of oligonucleotide microarray and pathway analysis, we elucidated significant changes in the transcriptome with development in sheep carotid arteries.

Results: As compared with adult, we demonstrate a U-shaped relationship of gene expression in major cerebrovascular network/pathways during early life, e.g., the level of gene expression in the premature fetus and newborn is considerably greater than that of the near-term fetus. Specifically, cell proliferation, growth, and assembly pathway genes were upregulated during early life. In turn, as compared with adult, mitogen-activated protein kinase-extracellular regulated kinase, actin cytoskeleton, and integrin-signaling pathways were downregulated during early life.

Conclusion: In cranial vascular smooth muscle, highly significant changes occur in important cellular and signaling pathways with maturational development.

Figure 1

Functional pathways altered with development. Bar graph demonstrates functional pathways altered with development. N was 4 in each experimental group, and all groups were significantly different compared to adult (P < 0.05). White, black, and grey bars shows comparison of adult with premature fetus, near-term fetus, and newborn, respectively.

Figure 2

Chief canonical pathways altered with development. Significant differences [−log(p-value)] in the (A) ERK-MAPK, (B) IGF1, (C) Ras Homolog Gene Family Member A (RhoA), (D) Integrin, (E) Role of checkpoint (CHK) proteins, and (F) Actin cytoskeleton signaling pathways in the carotid arteries from premature fetus, near-term fetus, and newborn lamb, compared to adult are shown in a line-graph format. N was 4 in each experimental group, and all groups were significantly different compared to adult (P < 0.05).

Figure 3

Real-time PCR validation of microarray analysis. Demonstrates changes in the expression of (A) STMN1, (B) FLNA, and (C) MYLK mRNA levels in the carotid arteries from premature fetus, near-term fetus, and newborn lamb, compared to adult as determined by quantitative real-time PCR analysis. N was 4 in each experimental group, and all groups were significantly different compared to adult (P < 0.05).