Disruption of CTCF-YY1-dependent looping of the human papillomavirus genome activates differentiation-induced viral oncogene transcription.

The complex life cycle of oncogenic human papillomavirus (HPV) initiates in undifferentiated basal epithelial keratinocytes where expression of the E6 and E7 oncogenes is restricted. Upon epithelial differentiation, E6/E7 transcription is increased through unknown mechanisms to drive cellular proliferation required to support virus replication. We report that the chromatin-organising CCCTC-binding factor (CTCF) promotes the formation of a chromatin loop in the HPV genome that epigenetically represses viral enhancer activity controlling E6/E7 expression. CTCF-dependent looping is dependent on the expression of the CTCF-associated Yin Yang 1 (YY1) transcription factor and polycomb repressor complex (PRC) recruitment, resulting in trimethylation of histone H3 at lysine 27. We show that viral oncogene up-regulation during cellular differentiation results from YY1 down-regulation, disruption of viral genome looping, and a loss of epigenetic repression of viral enhancer activity. Our data therefore reveal a key role for CTCF-YY1-dependent looping in the HPV life cycle and identify a regulatory mechanism that could be disrupted in HPV carcinogenesis

Variability of Female Responses to Conspecific vs. Heterospecific Male Mating Calls in Polygynous Deer: An Open Door to Hybridization?

Males of all polygynous deer species (Cervinae) give conspicuous calls during the reproductive season. The extreme interspecific diversity that characterizes these vocalizations suggests that they play a strong role in species discrimination. However, interbreeding between several species of Cervinae indicates permeable interspecific reproductive barriers. This study examines the contribution of vocal behavior to female species discrimination and mating preferences in two closely related polygynous deer species known to hybridize in the wild after introductions. Specifically, we investigate the reaction of estrous female red deer (Cervus elaphus) to playbacks of red deer vs. sika deer (Cervus nippon) male mating calls, with the prediction that females will prefer conspecific calls. While on average female red deer preferred male red deer roars, two out of twenty females spent more time in close proximity to the speaker broadcasting male sika deer moans. We suggest that this absence of strict vocal preference for species-specific mating calls may contribute to the permeability of pre-zygotic reproductive barriers observed between these species. Our results also highlight the importance of examining inter-individual variation when studying the role of female preferences in species discrimination and intraspecific mate selection

Loss of CTCF-YY1-mediated regulation of human papillomavirus oncogene transcription in HPV-driven disease

Persistent human papillomavirus (HPV) infection is a risk factor for oropharyngeal squamous cell carcinoma (OPSCC). The viral oncogenes E6 and E7 drive cell growth and delay differentiation. Expression of E6/E7 is tightly regulated during the HPV life cycle. In basal keratinocytes, the CCCTC-binding factor (CTCF) binds the HPV18 episome at the E2 open reading frame to mediate the formation of an epigenetically repressed chromatin loop through association with Yin Yang 1 (YY1) bound at the viral enhancer. Following differentiation, depletion in YY1 results in chromatin remodelling and increased transcription. As such, YY1 is a key mediator of differentiation dependent depression of HPV oncogene transcription. Whilst CTCF-YY1-mediated chromatin looping is essential in regulating early gene expression during the HPV life cycle, it is unclear whether this mechanism of transcription control is deregulated during carcinogenesis. Using physiological models of HPV-induced disease and OPSCC cell lines we show a switch in YY1 function from transcriptional repression to transactivation of the HPV early promoter. YY1 enrichment at the viral enhancer becomes significantly increased during disease progression which is coincident with open chromatin and high E6/E7 expression. We show a robust enrichment of active histone modifications histone H3 acetylation (H3K27Ac) and histone H4 methylation (H3K4me3) when YY1 is bound. Following depletion of YY1 we see a significant reduction in E6/E7 expression as a result of reduced chromatin accessibility at the viral enhancer. Interestingly, in the context of transcriptional regulation, CTCF appears to be redundant within OPSCCs where it exerts no effect on E6/E7 transcription. Overall, we describe a mechanism in which YY1 functions to drive the overexpression of E6 and E7 during the progression of HPV-driven oropharyngeal carcinomas

Research data supporting the thesis "Alterations to Host Lipid Metabolism and the Role of PPARγ Following HPV18 Establishment"

Primary human primary foreskin keratinocytes (HFKs) and normal immortalised keratinocytes (NIKs) were transfected with a recircularised human papillomavirus 18 (HPV18) genome to compare the effects of virus establishment upon the host transcriptome

Tiltrotor Aeroacoustic Code (TRAC) Prediction Assessment And Initial Comparisons With Tram Test Data

A prediction sensitivity assessment to inputs and blade modeling is presented for the TiltRotor Aeroacoustic Code (TRAC). For this study, the nonCFD prediction system option in TRAC is used. Here, the comprehensive rotorcraft code, CAMRAD.Mod1, coupled with the high-resolution sectional loads code HIRES, predicts unsteady blade loads to be used in the noise prediction code WOPWOP. The sensitivity of the predicted blade motions, blade airloads, wake geometry, and acoustics is examined with respect to rotor rpm, blade twist and chord, and to blade dynamic modeling. To accomplish this assessment, an interim input-deck for the TRAM test model and an input-deck for a reference test model are utilized in both rigid and elastic modes. Both of these test models are regarded as near scale models of the V-22 proprotor (tiltrotor). With basic TRAC sensitivities established, initial TRAC predictions are compared to results of an extensive test of an isolated model proprotor. The test was that of t..

Initial Stages of Development for an Intersectoral Network on Trans-Affirming Practice to Better Support Sexual Assault Survivors in Ontario

Background: Sexual violence against transgender (trans) persons is a complex public health issue that requires the coordinated effort of multiple sectors to address. A 2017 survey of Sexual Assault Nurse Examiners (SANEs) working within Ontario’s 36 Sexual Assault/Domestic Violence Treatment Centres (SA/DVTCs) revealed a need for training in the provision of trans-affirming care and highlighted a gap in knowledge related to local trans-positive organizations. In response, the successful design, pilot, and evaluation of a curriculum on trans-affirming care for SANEs was completed in 2018. However, there remained a pressing need to connect SANEs with trans-positive service providers across sectors to enhance the provision of care to trans survivors throughout Ontario. Goals and Objectives: To initiate the development a provincial intersectoral network on trans-affirming practice to better support sexual assault survivors by mobilizing knowledge on the new curriculum and connecting SA/DVTCs with local trans-positive community organizations. Approach: Guided by the Lifecycle Model of Network Development, seven regional meetings across the province were facilitated with leaders from SA/DVTCs and local trans-positive organizations. Key insights from meeting activities were transcribed and analyzed. Results: 106 representatives from 96 SA/DVTCs and trans-positive organizations attended a meeting between 7 June and 11 July 2019. 93 organizations expressed interest in being a part of the ongoing development of the network, in addition to 31 organizations unable to attend the meetings. 18 themes related to regional and provincial intersectoral collaboration to address sexual violence against trans communities were identified. Implications: As indicated by high meeting attendance and ongoing interest in developing a network, sexual violence against trans persons is a timely issue relevant to the enhancement of public health policy and practice across sectors. Informed by data gathered across the meetings, we aim to further consolidate the network, including working toward its maturation and sustainability

Research data supporting the thesis "Alterations to Host Lipid Metabolism and the Role of PPARγ Following HPV18 Establishment"

Primary human primary foreskin keratinocytes (HFKs) and normal immortalised keratinocytes (NIKs) were transfected with a recircularised human papillomavirus 18 (HPV18) genome to compare the effects of virus establishment upon the host transcriptome

Disruption of CTCF-YY1-dependent looping of the human papillomavirus genome activates differentiation-induced viral oncogene transcription.

The complex life cycle of oncogenic human papillomavirus (HPV) initiates in undifferentiated basal epithelial keratinocytes where expression of the E6 and E7 oncogenes is restricted. Upon epithelial differentiation, E6/E7 transcription is increased through unknown mechanisms to drive cellular proliferation required to support virus replication. We report that the chromatin-organising CCCTC-binding factor (CTCF) promotes the formation of a chromatin loop in the HPV genome that epigenetically represses viral enhancer activity controlling E6/E7 expression. CTCF-dependent looping is dependent on the expression of the CTCF-associated Yin Yang 1 (YY1) transcription factor and polycomb repressor complex (PRC) recruitment, resulting in trimethylation of histone H3 at lysine 27. We show that viral oncogene up-regulation during cellular differentiation results from YY1 down-regulation, disruption of viral genome looping, and a loss of epigenetic repression of viral enhancer activity. Our data therefore reveal a key role for CTCF-YY1-dependent looping in the HPV life cycle and identify a regulatory mechanism that could be disrupted in HPV carcinogenesis