Transcriptome Analysis of Bovine Oocytes From Distinct Follicle Sizes: Insights From Correlation Network Analysis
MOLECULAR REPRODUCTION AND DEVELOPMENT
Authors: Labrecque, Remi; Fournier, Eric; Sirard, Marc-Andre
Abstract
Follicle size is recognized as a predictor of the potential for the enclosed oocyte to yield an embryo following in vitro maturation and in vitro fertilization. Oocytes from larger follicles are more likely to reach the blastocyst stage than those from smaller follicles. A growing oocyte accumulates all the transcripts needed to ensure development until the maternal embryonic transition, and this accumulation must be completed before the period of transcriptional arrest. Accordingly, the transcriptomes of bovine germinal-vesicle-stage oocytes collected from follicles of increasing sizes (< 3, 3 - 5, > 5 - 8, and > 8mm) were evaluated, using the EmbryoGENE bovine transcriptomic platform (custom Agilent 4 - 44 K), to better understand transcriptional modulation in the oocyte as the follicle becomes larger. Microarray analyses revealed very few differences between oocytes from small follicles (< 3 vs. 3 - 5mm), whereas an important number of differences were detected at the mRNA level between oocytes from larger follicles. Weighted gene correlation network analysis allowed for the identification of several hub genes involved in crucial functions such as transcriptional regulation (TAF2), chromatin remodeling (PPP1CB), energy production (SLC25A31), as well as transport of key molecules within the cell (NAGPA, CYHR1, and SLC3A12). The results presented here thus reinforce the hypothesis that developmental competence acquisition cannot be seen as a simple one-step process, especially in regards to the modulation of mRNA. (C) 2016 Wiley Periodicals, Inc.
Frequent MYC coamplification and DNA hypomethylation of multiple genes on 8q in 8p11-p12-amplified breast carcinomas
ONCOGENESIS
Authors: Parris, T. Z.; Kovacs, A.; Hajizadeh, S.; Nemes, S.; Semaan, M.; Levin, M.; Karlsson, P.; Helou, K.
Abstract
Genetic and epigenetic (DNA methylation, histone modifications, microRNA expression) crosstalk promotes inactivation of tumor suppressor genes or activation of oncogenes by gene loss/hypermethylation or duplications/hypomethylation, respectively. The 8p11-p12 chromosomal region is a hotspot for genomic aberrations (chromosomal rearrangements, amplifications and deletions) in several cancer forms, including breast carcinoma where amplification has been associated with increased proliferation rates and reduced patient survival. Here, an integrative genomics screen (DNA copy number, transcriptional and DNA methylation profiling) performed in 229 primary invasive breast carcinomas identified substantial coamplification of the 8p11-p12 genomic region and the MYC oncogene (8q24.21), as well as aberrant methylation and transcriptional patterns for several genes spanning the 8q12.1-q24.22 genomic region (ENPP2, FABP5, IMPAD1, NDRG1, PLEKHF2, RRM2B, SQLE, TAF2, TATDN1, TRPS1, VPS13B). Taken together, our findings suggest that MYC activity and aberrant DNA methylation may also have a pivotal role in the aggressive tumor phenotype frequently observed in breast carcinomas harboring 8p11-p12 regional amplification.