Abstract
ABSTRACTRad50-interacting protein 1 (Rint1) associates with the DNA damage response protein Rad50 during the transition from the S phase to the G2/M phase and functions in radiation-induced G2 checkpoint control. It has also been demonstrated that Rint1 is essential in vesicle trafficking from the Golgi apparatus to the endoplasmic reticulum (ER) through an interaction with Zeste-White 10 (ZW10). We have isolated a novel interaction between Rint1 and the human papillomavirus 16 (HPV16) transcription and replication factor E2. E2 binds to Rint1 within its ZW10 interaction domain, and we show that in the absence of E2, Rint1 is localized to the ER and associates with ZW10. E2 expression results in a disruption of the Rint1-ZW10 interaction and an accumulation of nuclear Rint1, coincident with a significant reduction in vesicle movement from the ER to the Golgi apparatus. Interestingly, nuclear Rint1 and members of the Mre11/Rad50/Nbs1 (MRN) complex were found in distinct E2 nuclear foci, which peaked during mid-S phase, indicating that the recruitment of Rint1 to E2 foci within the nucleus may also result in the recruitment of this DNA damage-sensing protein complex. We show that exogenous Rint1 expression enhances E2-dependent virus replication. Conversely, the overexpression of a truncated Rint1 protein that retains the E2 binding domain but not the Rad50 binding domain acts as a dominant negative inhibitor of E2-dependent HPV replication. Put together, these experiments demonstrate that the interaction between Rint1 and E2 has an important function in HPV replication.IMPORTANCE HPV infections are an important driver of many epithelial cancers, including those within the anogenital and oropharyngeal tracts. The HPV life cycle is tightly regulated and intimately linked to the differentiation of the epithelial cells that it infects. HPV replication factories formed in the nucleus are locations where viral DNA is copied to support virus persistence and amplification of infection. The recruitment of specific cellular protein complexes to these factories aids efficient and controlled viral replication. We have identified a novel HPV-host interaction that functions in the cellular response to DNA damage and cell cycle control. We show that the HPV E2 protein targets Rad50-interacting protein 1 (Rint1) to facilitate virus genome replication. These findings add to our understanding of how HPV replicates and the host cell pathways that are targeted by HPV to support virus replication. Understanding these pathways will allow further research into novel inhibitors of HPV genome replication.
Highlights
Rad50-interacting protein 1 (Rint1) associates with the DNA damage response protein Rad50 during the transition from the S phase to the G2/M phase and functions in radiation-induced G2 checkpoint control
Attempts to verify this interaction by coimmunoprecipitation of exogenous proteins in human cells were unfruitful due to an apparent instability of Rint1 in the presence of overexpressed ChlR1, we noticed that the coexpression of bovine papillomavirus 1 (BPV1) E2, which targets ChlR1 for the stable maintenance of BPV1 genomes [35, 36], was able to stabilize the Rint1 protein in the presence of exogenously expressed ChlR1
We were able to coimmunoprecipitate the human papillomavirus 16 (HPV16) E2 protein with endogenous Rint1 (Fig. 1C), indicating that this interaction occurs at physiological levels of Rint1 and that the HA epitope tag fused to exogenously expressed Rint1 does not induce binding
Summary
Rad50-interacting protein 1 (Rint1) associates with the DNA damage response protein Rad during the transition from the S phase to the G2/M phase and functions in radiation-induced G2 checkpoint control. We have identified a novel HPV-host interaction that functions in the cellular response to DNA damage and cell cycle control. In the upper layers of the epithelium, E6 and E7 expression levels are attenuated, resulting in host cell differentiation This facilitates late promoter activation and the expression of E1ٙE4, resulting in the amplification of replication, and the virus capsid proteins L1 and L2, required for the packaging of viral genomes. All of these life cycle events are coordinated through numerous virus-host interactions whereby HPV manipulates important cellular networks to support the persistence of infection and efficient life cycle completion. It has been suggested that MRN participates in the ataxia telangiectasiarelated (ATR)-dependent DDR signaling cascade [11]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
