We aimed to determine gene expression patterns in the anterior pituitary (AP) of heifers
before and after ovulation via deep sequencing of the transcriptome (RNA-seq) to identify
new genes and clarify important pathways. Heifers were slaughtered on the estrus day
(pre-ovulation; n=5) or 3 days after ovulation (post-ovulation; n=5) for AP collection. We
randomly selected 4 pre-ovulation and 4 post-ovulation APs, and the ribosomal RNA-depleted
poly (A)+RNA were prepared to assemble next-generation sequencing libraries. The bovine
APs expressed 12,769 annotated genes at pre- or post-ovulation. The sum of the reads per
kilobase of exon model per million mapped reads (RPKM) values of all transcriptomes were
599,676 ± 38,913 and 668,209 ± 23,690, and 32.2 ± 2.6% and 44.0 ± 4.4% of these
corresponded to the AP hormones in the APs of pre- and post-ovulation heifers,
respectively. The bovine AP showed differential expression of 396 genes
(P<0.05) in the pre- and post-ovulation APs. The 396 genes included
two G-protein-coupled receptor (GPCR) genes (GPR61 and
GPR153) and those encoding 13 binding proteins. The AP also expressed
259 receptor and other 364 binding proteins. Moreover, ingenuity pathway analysis for the
396 genes revealed (P=2.4 × 10−3) a canonical pathway linking
GPCR to cytoskeleton reorganization, actin polymerization, microtubule growth, and gene
expression. Thus, the present study clarified the novel genes found to be differentially
expressed before and after ovulation and clarified an important pathway in the AP.
Breast cancer is the most frequent tumor in women, and in nearly two-thirds of cases, the tumors express estrogen receptor α (ERα, encoded by ESR1). Here, we performed whole-exome sequencing of 16 breast cancer tissues classified according to ESR1 expression and 12 samples of whole blood, and detected 310 somatic mutations in cancer tissues with high levels of ESR1 expression. Of the somatic mutations validated by a different deep sequencer, a novel nonsense somatic mutation, c.2830 C>T; p.Gln944*, in transcriptional regulator switch-independent 3 family member A (SIN3A) was detected in breast cancer of a patient. Part of the mutant protein localized in the cytoplasm in contrast to the nuclear localization of ERα, and induced a significant increase in ESR1 mRNA. The SIN3A mutation obviously enhanced MCF7 cell proliferation. In tissue sections from the breast cancer patient with the SIN3A c.2830 C>T mutation, cytoplasmic SIN3A localization was detected within the tumor regions where nuclear enlargement was observed. The reduction in SIN3A mRNA correlates with the recurrence of ER-positive breast cancers on Kaplan-Meier plots. These observations reveal that the SIN3A mutation has lost its transcriptional repression function due to its cytoplasmic localization, and that this repression may contribute to the progression of breast cancer.
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