Genomic profiling of bovine corpus luteum maturation

Abstract

To unveil novel global changes associated with corpus luteum (CL) maturation, we analyzed transcriptome data for the bovine CL on days 4 and 11, representing the developing vs. mature gland. Our analyses revealed 681 differentially expressed genes (363 and 318 on day 4 and 11, respectively), with ≥2 fold change and FDR of <5%. Different gene ontology (GO) categories were represented prominently in transcriptome data at these stages (e.g. days 4: cell cycle, chromosome, DNA metabolic process and replication and on day 11: immune response; lipid metabolic process and complement activation). Based on bioinformatic analyses, select genes expression in day 4 and 11 CL was validated with quantitative real-time PCR. Cell specific expression was also determined in enriched luteal endothelial and steroidogenic cells. 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.

Systematic Identification of Housekeeping Genes Possibly Used as References in Caenorhabditis elegans by Large-Scale Data Integration

“…Additionally, our results strongly support that rpl-33 and rps-26 are stable and reliable reference genes in microarray data. Likely, rps-26 has been widely used as a reference gene to normalize gene expression in Homo sapiens [76], Bovine corpus [77], Monotropa hypopitys [78], and Millerozyma (Pichia) farinose [79]. Housekeeping genes rps-2 and rps-4 were also identified as stable reference genes in RNA-seq data of C. elegans.…”

Inflammation and angiogenesis in the corpus luteum

“…18 New vessels are developed from preexisting ones, which make the CL grow rapidly and endocrine function also develops rapidly. [19][20][21] There are a series of essential morphological and biochemical changes that are induced by the rapid increase in luteinizing hormone. 22 The basement membrane divides the CL into two layers: a thecal layer and granulosa cell layer.…”

“…The development of the CL is accompanied by rapid angiogenesis, the rate of which even rivals the rates of vascular formation in the fastest growing tumors . New vessels are developed from preexisting ones, which make the CL grow rapidly and endocrine function also develops rapidly . There are a series of essential morphological and biochemical changes that are induced by the rapid increase in luteinizing hormone .…”

Applications of large-scale molecular profiling techniques to the study of the corpus luteum

“…Overall, these and other studies demonstrate that chemokines and cytokines appear to be key regulators of both luteal regression and luteal survival during pregnancy. Kfir et al, 2018;2 Goravanahally et al, 2009;3 Mondal et al, 2011;4 Fatima et al, 2012;5 Romereim et al, 2017;6 Baddela et al, 2018;7 Talbott et al, 2017;8 Shah et al, 2014;9 Ochoa et al, 2018. The advent of RNAseq provided more sensitive and more accurate detection of mRNA, allowing for more comprehensive studies of the luteal transcriptome, and providing the opportunity to reveal potentially important transcripts that were previously unrecognized. In a recent RNAseq study comparing transcript abundance in bovine CL of day 17 of the estrous cycle and day 17 of pregnancy, 144 differentially abundant mRNA were reported and immune signaling pathways were among those predicted to be modulated in early pregnancy, as well as novel potential regulators of luteal rescue, including PPAR signaling and PDGF signaling (Hughes et al, 2018; Penn State University, Center for Reproductive Biology and Health, University Park, PA USA; unpublished data) Moore et al (2016) used RNAseq to determine if CL and endometria of cattle of low or high genetic merit for fertility contained differentially abundant mRNA.…”