Disruption of endometrial NELF transcriptional pausing complex impairs early pregnancy

Authors

• SC Hewitt
• W Winuthayanon
• KJ Hamilton
• L Donoghue
• JF Foley
• GW Muse
• JP Lydon
• FJ DeMayo
• K Adelman
• KS Korach

Abstract

Recent studies have linked gene regulation through Pol II pausing and nuclear receptors. Pausing of Pol II during early transcriptional elongation is an important rate limiting step where an engaged transcription complex pauses near a transcription start site (TSS). Previously we performed Pol II ChIP-seq on mouse uterine tissue, revealing promoter proximal enrichment of Pol II at a number of genes relevant to reproductive biology. Here we used a conditional knock-out approach to disrupt the transcriptional pausing complex NELF (Negative Elongation Factor) in uterine cells by deleting the NELF-B subunit using PRcre (NELF-B cKO).. NELF-B cKO were infertile, with smaller implantation sites by 8.5 dpc. Closer examination indicated impaired decidualization of by 7.5-8.5 dpc. Comparable levels of the decidual marker Prl8a2, which exhibits low promoter-proximal enrichment of Pol II in the uterus, is present in WT and NELF-B cKO 7.5 dpc implantation sites. Bmp2, a gene with high promoter-proximal Pol II enrichment, is lower in 7.5 dpc NELF-B cKO uteri than in WT. These finding are consistent with inadequate decidualization. After artificial or in vitro decidualization, WT controls responded as expected, however, NELF-B cKO exhibited minimal uterine decidualization. Overall, these findings indicate that Pol II pausing is not necessary to initiate but is required to maintain pregnancy. Disruption of the NELF complex results in pregnancy loss at a time relevant to decidualization, indicating a crucial role for NELF-mediated transcriptional pausing in endometrial remodeling in response to PR and embryonic initiated signals needed to support full-term pregnancy.

Scientific Focus Area: Molecular Biology and Biochemistry

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