Transcriptomic changes between early and mid cyclic bovine corpus luteum.

What is it about?

To unveil novel regulatory mechanisms and gain more comprehensive knowledge of the changes that accompany CL maturation, we analyzed transcriptome data for the bovine CL on early vs mature CL (days 4 and 11, respectively). Based on bioinformatic analyses, the profile of select gene expression in these CL and in isolated luteal cell types (endothelial and steroidogenic) was validated with quantitative real-time PCR (qPCR). The analysis revealed profound differences in networks, pathways and specific genes expressed in CL on days 4 and 11, representing the early, developing gland vs. the mature bovine CL at its plateau phase.s

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Why is it important?

Genes related to the angiogenic process such as NOS3, which maintains dilated vessels and MMP9, matrix degrading enzyme, were higher on day 4. Importantly, our data suggests day 11 CL acquire mechanisms to prevent blood vessel sprouting and promote their maturation by expressing NOTCH4 and JAG1, greatly enriched in luteal endothelial cells. Another endothelial specific gene, CD300LG, was identified here in the CL for the first time. CD300LG is an adhesion molecule enabling lymphocyte migration, its higher levels at mid cycle are expected to support the transmigration of immune cells into the CL at this stage. Together with steroidogenic genes, most of the genes regulating de-novo cholesterol biosynthetic pathway (e.g HMGCS, HMGCR) and cholesterol uptake from plasma (LDLR, APOD and APOE) were upregulated in the mature CL. These findings provide new insight of the processes involved in CL maturation including blood vessel growth and stabilization, leucocyte transmigration as well as progesterone synthesis as the CL matures.