Clinical outcomes following intraoperative pedicle disruption in fibula free flaps.

OBJECTIVES: Iatrogenic injury of the fibula free flap pedicle is rare. Postoperative flap survival and reconstructive outcomes following intraoperative pedicle severance are unknown. This study assesses free flap outcomes following accidental severance of the peroneal vessels. METHODS: Multi-institutional retrospective chart review from 2000 to 2020. RESULTS: Of 2975 harvested fibula free flaps, 26 had a history of pedicle severance during surgical reconstruction. Reasons for intraoperative pedicle severance included transection during muscular dissection 10/26 (39%), accidental severance with the bone saw 12/26 (46%), and other 4/26 (15.6%). The surgeon responsible for pedicle severance included residents 5/26 (19%), fellows 10/26 (39%), attendings 10/26 (39%), and unknown 1/26 (3.9%). The pedicle artery and vein were severed 10/26 (39%), artery 8/26 (31%), and vein 8/26 (31%). Truncated pedicle vessels were used 3/26 (11.7%), intraoperative anastomoses were performed 23/26 (89%). Postoperative revision in the OR within 7 days of surgery was required 6/26 (23%); 4 flaps were salvaged and 2 flaps failed, both arterial thrombosis. Flap failure was attributed to vascular thrombosis. Long-term flap survival and successful reconstructions were reported 24/26 (92%). CONCLUSION: Accidental severance of fibula free flap pedicle vessels can be corrected with intraoperative repair, without affecting long-term flap survival or reconstructive outcomes. Protecting the flap vessels while using the bone saw and during intramuscular dissection prevents accidental severance.

Instructional Models for Course-Based Research Experience (CRE) Teaching.

The course-based research experience (CRE) with its documented educational benefits is increasingly being implemented in science, technology, engineering, and mathematics education. This article reports on a study that was done over a period of 3 years to explicate the instructional processes involved in teaching an undergraduate CRE. One hundred and two instructors from the established and large multi-institutional SEA-PHAGES program were surveyed for their understanding of the aims and practices of CRE teaching. This was followed by large-scale feedback sessions with the cohort of instructors at the annual SEA Faculty Meeting and subsequently with a small focus group of expert CRE instructors. Using a qualitative content analysis approach, the survey data were analyzed for the aims of inquiry instruction and pedagogical practices used to achieve these goals. The results characterize CRE inquiry teaching as involving three instructional models: 1) being a scientist and generating data; 2) teaching procedural knowledge; and 3) fostering project ownership. Each of these models is explicated and visualized in terms of the specific pedagogical practices and their relationships. The models present a complex picture of the ways in which CRE instruction is conducted on a daily basis and can inform instructors and institutions new to CRE teaching.

Multiple Myeloma Presenting as Massive Amyloid Deposition in a Parathyroid Gland Associated with Amyloid Goiter: A Medullary Thyroid Carcinoma Mimic on Intra-operative Frozen Section.

Clinical examples of amyloid deposition in parathyroid glands are exceedingly rare and usually present as an incidental finding in a patient with amyloid goiter. Here, we present the first histologically documented case of parathyroid amyloid deposition that presented as a mass. The patient did not have hyperparathyroidism. The parathyroid gland was submitted for intra-operative frozen section and concern for medullary thyroid carcinoma was raised. An important histologic clue arguing against medullary thyroid carcinoma was the evenly dispersed nature of the amyloid. Histologic perinuclear clearing and parathyroid hormone immunohistochemistry confirmed parathyroid origin on permanent sections. The patient was also found to have associated amyloid goiter. Mass spectrometry of the amyloid showed it to be composed of kappa light chains. On further work-up, the patient was diagnosed with multiple myeloma. Awareness of parathyroid amyloid deposition is important as it is a histologic mimic of medullary thyroid carcinoma, especially on frozen section. Amyloid typing with evaluation for multiple myeloma in any patient with kappa or lambda light chain restriction is also important.

Biomarker and Tumor Responses of Oral Cavity Squamous Cell Carcinoma to Trametinib: A Phase II Neoadjuvant Window-of-Opportunity Clinical Trial.

Purpose: Ras/MEK/ERK pathway activation is common in oral cavity squamous cell carcinoma (OCSCC). We performed a neoadjuvant (preoperative) trial to determine the biomarker and tumor response of OCSCC to MEK inhibition with trametinib.Experimental Design: Patients with stage II-IV OCSCC received trametinib (2 mg/day, minimum 7 days) prior to surgery. Primary tumor specimens were obtained before and after trametinib to evaluate immunohistochemical staining for p-ERK1/2 and CD44, the primary endpoint. Secondary endpoints included changes in clinical tumor measurements and metabolic activity [maximum standardized uptake values (SUVmax) by F-18 fluorodeoxyglucose positron emission tomography/CT), and in tumor downstaging. Drug-related adverse events (AE) and surgical/wound complications were evaluated.Results: Of 20 enrolled patients, 17 (85%) completed the study. Three patients withdrew because of either trametinib-related (n = 2: nausea, duodenal perforation) or unrelated (n = 1: constipation) AEs. The most common AE was rash (9/20 patients, 45%). Seventeen patients underwent surgery. No unexpected surgical/wound complications occurred. Evaluable matched pre- and posttrametinib specimens were available in 15 (88%) of these patients. Reduction in p-ERK1/2 and CD44 expression occurred in 5 (33%) and 2 (13%) patients, respectively. Clinical tumor response by modified World Health Organization criteria was observed in 11 of 17 (65%) evaluable patients (median 46% decrease, range 14%-74%). Partial metabolic response (≥25% reduction in SUVmax) was observed in 6 of 13 (46%) evaluable patients (median 25% decrease, range 6%-52%). Clinical-to-pathologic tumor downstaging occurred in 9 of 17 (53%) evaluable patients.Conclusions: Trametinib resulted in significant reduction in Ras/MEK/ERK pathway activation and in clinical and metabolic tumor responses in patients with OCSCC. Clin Cancer Res; 23(9); 2186-94. ©2016 AACR.

Glycan specificity of neuraminidases determined in microarray format.

Neuraminidases hydrolytically remove sialic acids from glycoconjugates. Neuraminidases are produced by both humans and their pathogens, and function in normal physiology and in pathological events. Identification of neuraminidase substrates is needed to reveal their mechanism of action, but high-throughput methods to determine glycan specificity of neuraminidases are limited. Here we use two glycan labeling reactions to monitor neuraminidase activity toward glycan substrates. While both periodate oxidation and aniline-catalyzed oxime ligation (PAL) and galactose oxidase and aniline-catalyzed oxime ligation (GAL) can be used to monitor neuraminidase activity toward glycans in microtiter plates, only GAL accurately measured neuraminidase activity toward glycans displayed on a commercial glass slide microarray. Using GAL, we confirm known linkage specificities of three pneumococcal neuraminidases and obtain new information about underlying glycan specificity.

Granulomatosis with polyangiitis (Wegener's granulomatosis) causing atlantoaxial instability: a case report.

BACKGROUND CONTEXT: No previous cases of atlantoaxial instability due to granulomatosis with polyangiitis have been reported. PURPOSE: The aim of this study was to report a case of granulomatosis with polyangiitis causing atlantoaxial instability. STUDY DESIGN: This is a case report. PATIENT SAMPLE: A 45-year-old woman participated in this study. OUTCOME MEASURES: The patient's pain and atlantoaxial instability were resolved. METHODS: A 45-year-old Caucasian woman with a large ulcerative lesion in her oropharynx initially presented with chronic sinusitis, pharyngitis, and severe odynophagia. Years after her original symptoms began, she developed neck pain radiating into her upper trapezial region and shoulders. RESULTS: Atlantoaxial fusion was performed on the patient, resolving her neck, upper trapezial, and shoulder pain. She was diagnosed with granulomatosis with polyangiitis (formerly Wegener's granulomatosis) and treated with cyclophosphamide. CONCLUSIONS: Granulomatosis with polyangiitis should be part of the working differential diagnosis for non-traumatic cervical spine injury. The atlantoaxial instability can be managed with stabilization, and the disease process itself can be treated with cyclophosphamide.

Lower Trapezius Flap for Reconstruction of Posterior Scalp and Neck Defects after Complex Occipital-Cervical Surgeries.

Objectives To review the indications, techniques, and outcomes for a series of patients in whom the lower trapezius flaps was used for repair of complex posterior scalp and neck defects after posterior occipital-cervical surgeries. Design Retrospective case series. Setting Tertiary academic hospital. Participants A retrospective review of cases that required complex occipital-cervical repair was performed to identify patients who underwent reconstruction using the lower trapezius flap. Data collected included demographics, clinical presentations, surgical anatomy, operative techniques, and outcomes with review of the pertinent literature. Outcomes Nine patients who underwent reconstruction using the lower trapezius flap were identified. Prior surgical interventions included five complex tumor resections, two patients with multiple instrumented cervical spine surgeries, one patient with a craniotomy for attempted extracranial to intracranial arterial bypass for a basilar aneurysm repair, and a posterior occipital-cervical decompression after trauma. During the median follow-up period of 7 months, all nine single-stage reconstructions resulted in successful healing without major surgical complications. Conclusion Lower trapezius island flaps provide a reliable option for the reconstruction of complex scalp and neck defects that develop after complex occipital-cervical surgeries.

Long-term Functional Outcomes of Total Glossectomy With or Without Total Laryngectomy.

IMPORTANCE: The optimal reconstruction of total glossectomy defects with or without total laryngectomy is controversial. Various pedicled and free tissue flaps have been advocated, but long-term data on functional outcomes are not available to date. OBJECTIVES: To compare various total glossectomy defect reconstructive techniques used by multiple institutions and to identify factors that may lead to improved long-term speech and swallowing function. DESIGN, SETTING, AND PARTICIPANTS: A multi-institutional, retrospective review of electronic medical records of patients undergoing total glossectomy at 8 participating institutions between June 1, 2001, and June 30, 2011, who had a minimal survival of 2 years. INTERVENTION: Total glossectomy with or without total laryngectomy. MAIN OUTCOMES AND MEASURES: Demographic and surgical factors were compiled and correlated with speech and swallowing outcomes. RESULTS: At the time of the last follow-up, 45% (25 of 55) of patients did not have a gastrostomy tube, and 76% (42 of 55) retained the ability to verbally communicate. Overall, 75% (41 of 55) of patients were tolerating at least minimal nutritional oral intake. Feeding tube dependence was not associated with laryngeal preservation or the reconstructive techniques used, including flap suspension, flap innervation, or type of flap used. Laryngeal preservation was associated with favorable speech outcomes, such as the retained ability to verbally communicate in 97% of those not undergoing total laryngectomy (35 of 36 patients) vs 44% (7 of 16) in those undergoing total laryngectomy (P < .001), as well as those not undergoing total laryngectomy achieving some or all intelligible speech in 85% (29 of 34 patients) compared with 31% (4 of 13) undergoing total laryngectomy achieving the same intelligibility (P < .001). CONCLUSIONS AND RELEVANCE: In patients with total glossectomy, feeding tube dependence was not associated with laryngeal preservation or the reconstructive technique, including flap innervation and type of flap used. Laryngeal preservation was associated with favorable speech outcomes such as the retained ability to verbally communicate and higher levels of speech intelligibility.

Atlantoaxial subluxation and nasopharyngeal necrosis complicating suspected granulomatosis with polyangiitis.

Granulomatosis polyangiitis (GPA, formerly Wegener granulomatosis) is a vasculitis that typically involves the upper respiratory tract, lungs, and kidneys. The 2 established methods to confirm a suspicion of GPA are the antineutrophil cytoplasmic antibody (ANCA) test and biopsy. However, ANCA-negative cases have been known to occur, and it can be difficult to find biopsy evidence of granulomatous disease.We report a case of suspected granulomatosis with polyangiitis limited to the nasopharynx. With a negative ANCA and no histological evidence, our diagnosis was founded on the exclusion of other diagnoses and the response to cyclophosphamide therapy. This case is unique because the patient's lesion resulted in atlantoaxial instability, which required a posterior spinal fusion at C1-C2. This is the first reported case of suspected GPA producing damage to the cervical spine and threatening the spinal cord.

Nab-paclitaxel-based compared to docetaxel-based induction chemotherapy regimens for locally advanced squamous cell carcinoma of the head and neck.

We previously reported that nab-paclitaxel-based induction chemotherapy (IC) and concurrent chemoradiotherapy resulted in low relapse rates (13%) and excellent survival in head and neck squamous cell carcinoma (HNSCC). We compare the disease-specific survival (DSS) and overall survival (OS) between patients given nab-paclitaxel, cisplatin, and fluorouracil with cetuximab (APF-C) and historical controls given docetaxel, cisplatin, and fluorouracil with cetuximab (TPF-C). Patients with locally advanced HNSCC were treated with APF-C (n = 30) or TPF-C (n = 38). After 3 cycles of IC, patients were scheduled to receive cisplatin concurrent with definitive radiotherapy. T and N classification and smoking history were similar between the two groups and within p16-positive and p16-negative subsets. The median duration of follow-up for living patients in the APF-C group was 43.5 (range: 30-58) months versus 52 (range: 13-84) months for TPF-C. The 2-year DSS for patients treated with APF-C was 96.7% [95% Confidence Interval (CI): 85.2%, 99.8%] and with TPF-C was 77.6% (CI: 62.6%, 89.7%) (P = 0.0004). Disease progression that resulted in death was more frequent in the TPF-C group (39%) compared with the APF-C group (3%) when adjusted for competing risks of death from other causes (Gray's test, P = 0.0004). In p16 positive OPSCC, the 2-year DSS for APF-C was 100% and for TPF-C was 74.6% (CI: 47.4%, 94.6%) (P = 0.0019) and the 2-year OS for APF-C was 94.1% (CI: 65.0%, 99.2%) and for TPF-C was 74.6% (CI: 39.8%, 91.1%) (P = 0.013). In p16 negative HNSCC, the 2-year DSS for APF-C was 91.7% (CI: 67.6%, 99.6%) and for TPF-C was 82.6% (CI: 64.4%, 94.8%) (P = 0.092). A 2-year DSS and OS were significantly better with a nab-paclitaxel-based IC regimen (APF-C) compared to a docetaxel-based IC regimen (TPF-C) in p16-positive OPSCC.

Pre-radiotherapy feeding tube identifies a poor prognostic subset of postoperative p16 positive oropharyngeal carcinoma patients.

BACKGROUND: This study explores variables associated with poor prognosis in postoperative p16 positive oropharyngeal squamous cell carcinoma (OPSCC) patients undergoing adjuvant radiotherapy or chemoradiotherapy. Specifically, analysis was done related to timing of feeding tube insertion relative to radiotherapy. METHODS: From 1997-2009, of 376 consecutive patients with OPSCC, 220 received adjuvant IMRT, and 97 were p16 positive and eligible. Of these, 23 had feeding tube placement before IMRT (B-FT), 32 during/after IMRT (DA-FT), and 42 had no feeding tube (NO-FT). Feeding tubes were not placed prophylactically. These three groups were analyzed for differential tumor, patient, treatment, and feeding tube characteristics, as well as differences in overall survival (OS), disease free survival (DFS), and distant metastasis free survival (DMFS). RESULTS: Pre-RT FT insertion was associated with higher tumor size and depth, T (but not N) and overall stage, comorbidities, presence of chemotherapy, and less use of transoral laser microsurgery/transoral bovie. Additionally, time from surgery to IMRT completion was also statistically longer in the B-FT group. The feeding tube was permanent in 52% of patients in the B-FT group versus 16% in the DA-FT group (p = 0.0075). The 5-year OS for the NO-FT, DA-FT, and B-FT groups was 90%, 86%, and 50%, respectively. The 5-year DFS for the NO-FT, DA-FT, and B-FT groups was 87.6%, 83.6%, and 42.7%, respectively. Multivariate analysis showed that for OS and DFS, feeding tube placement timing and smoking history were statistically significant. CONCLUSION: Due to the poor prognosis of early FT insertion, the presence of FTs at time of radiotherapy consultation can be used as an alternate marker to identify a subset of p16 positive OPSCC patients that have a poor prognosis.

Reconstruction of composite oral cavity defects with temporalis flaps after prior treatment.

BACKGROUND: Reconstruction of composite oral cavity defects in the setting of prior surgery and radiotherapy presents a significant challenge. Although free tissue transfer has shown success in such situations, it is not without considerable risk. Regional pedicled flaps may provide a more suitable alternative. In certain patients, however, severe soft tissue fibrosis makes more conventional regional flaps impractical or impossible. In these situations, temporalis flaps (temporalis muscle and temporoparietal fascia flaps) are versatile options for coverage of complex defects. OBJECTIVE: To report our experience using pedicled temporalis flaps for reconstruction of composite oral cavity defects in patients with significant co-morbidities and prior treatment. METHODS: Three patients were identified and their medical records were reviewed. Their clinical courses and functional outcomes are described. We include a discussion of the operative technique and relevant literature. RESULTS: All patients had previously undergone extensive treatment. One patient needed reconstruction after resection of a third head and neck malignancy and two patients presented for treatment of osteoradionecrosis. A temporalis muscle flap was used to reconstruct composite oral cavity defects in two patients and a combined temporalis muscle and temporoparietal fascia flap was used for independent defects in one patient. All flaps survived. Functional status and pain improved or stabilized in all patients. There were no major or minor complications. CONCLUSION: In previously treated fields, where more conventional flaps are impractical, temporalis flaps are a suitable alternative to achieve a stable healing wound and prevent worsening of functional status.

Locoregional and free flap reconstruction of the lateral skull base.

Lateral temporal bone reconstruction after ablative surgery for malignancy, chronic infection, osteoradionecrosis, or trauma presents a challenge for the reconstructive surgeon. This complexity is due to the 3D nature of the region, potential dural exposure, and the possible need for external surface repair. Successful reconstruction therefore requires achieving separation of the dura, obliteration of volume defect, and external cutaneous repair. There is significant institutional bias on the best method of reconstruction of these defects. In this review, the advantages and disadvantages of reconstructive options will be discussed as well as the potential pitfalls and complications.

Phosphorylation of Merkel cell polyomavirus large tumor antigen at serine 816 by ATM kinase induces apoptosis in host cells.

Merkel cell carcinoma is a highly aggressive form of skin cancer. Merkel cell polyomavirus (MCV) infection and DNA integration into the host genome correlate with 80% of all Merkel cell carcinoma cases. Integration of the MCV genome frequently results in mutations in the large tumor antigen (LT), leading to expression of a truncated LT that retains pRB binding but with a deletion of the C-terminal domain. Studies from our laboratory and others have shown that the MCV LT C-terminal helicase domain contains growth-inhibiting properties. Additionally, we have shown that host DNA damage response factors are recruited to viral replication centers. In this study, we identified a novel MCV LT phosphorylation site at Ser-816 in the C-terminal domain. We demonstrate that activation of the ATM pathway stimulated MCV LT phosphorylation at Ser-816, whereas inhibition of ATM kinase activity prevented LT phosphorylation at this site. In vitro phosphorylation experiments confirmed that ATM kinase is responsible for phosphorylating MCV LT at Ser-816. Finally, we show that ATM kinase-mediated MCV LT Ser-816 phosphorylation may contribute to the anti-tumorigenic properties of the MCV LT C-terminal domain.

Patients undergoing total laryngectomy: an at-risk population for 30-day unplanned readmission.

IMPORTANCE: Patients undergoing total laryngectomy are at high risk for hospital readmission. Hospital readmissions are increasingly scrutinized because they are used as a metric of quality care and are subject to financial penalties. OBJECTIVE: To determine the rate of, reasons for, and risk factors that predict 30-day unplanned readmission for patients undergoing total laryngectomy. DESIGN, SETTING, AND PATIENTS: Retrospective cohort study at a single academic tertiary referral medical center. The study population comprised 155 patients who underwent total laryngectomy with or without flap closure between January 2007 and December 2012 as either a primary treatment or salvage treatment for prior nonsurgical management. INTERVENTIONS: Total laryngectomy. MAIN OUTCOMES AND MEASURES: Rate of 30-day unplanned readmission, readmission diagnoses, and risk factors for unplanned readmission. Univariable and multivariable logistic regression were performed to identify risk factors for unplanned readmission within 30 days of discharge. RESULTS: The 30-day unplanned readmission rate for patients following discharge after total laryngectomy was 26.5% (41 of 155). The most common readmission diagnoses were pharyngocutaneous fistula (27% of readmissions; n = 11) and stomal cellulitis (16% of readmissions; n = 7). The median time to unplanned readmission was 7 days. Thirty-four percent of readmissions (14 of 41) occurred within 3 days of discharge. Significant predictors of 30-day unplanned readmission on multivariable analysis were postoperative complication after discharge (odds ratio [OR], 11.50; 95% CI, 4.10-32.28), visit to the emergency department within 30 days after discharge (OR, 5.25; 95% CI, 1.84-14.99), salvage total laryngectomy (OR, 3.52; 95% CI, 1.56-13.12), and chyle fistula during the index hospitalization (OR, 5.25; 95% CI, 0.86-29.92). The discriminative ability of the model to predict unplanned readmission, as measured by the C statistic, was 0.88. CONCLUSIONS AND RELEVANCE: Patients undergoing total laryngectomy are an at-risk patient population with a high rate of unplanned readmission within 30 days of discharge. By identifying the risk factors that predict 30-day unplanned readmission, these data can be used to design and implement quality-improvement interventions to decrease readmissions.

Phosphorylation of large T antigen regulates merkel cell polyomavirus replication.

Merkel Cell Polyomavirus (MCPyV) was recently discovered as a novel human polyomavirus that is associated with ~80% of Merkel Cell Carcinomas. The Large Tumor antigen (LT) is an early viral protein which has a variety of functions, including manipulation of the cell cycle and initiating viral DNA replication. Phosphorylation plays a critical regulatory role for polyomavirus LT proteins, but no investigation of MCPyV LT phosphorylation has been performed to date. In this report mass spectrometry analysis reveals three unique phosphorylation sites: T271, T297 and T299. In vivo replication assays confirm that phosphorylation of T271 does not play a role in viral replication, while modification at T297 and T299 have dramatic and opposing effects on LT's ability to initiate replication from the viral origin. We test these mutants for their ability to bind, unwind, and act as a functional helicase at the viral origin. These studies provide a framework for understanding how phosphorylation of LT may dynamically regulate viral replication. Although the natural host cell of MCPyV has not yet been established, this work provides a foundation for understanding how LT activity is regulated and provides tools for better exploring this regulation in both natural host cells and Merkel cells.

Increased reward in ankle robotics training enhances motor control and cortical efficiency in stroke.

Robotics is rapidly emerging as a viable approach to enhance motor recovery after disabling stroke. Current principles of cognitive motor learning recognize a positive relationship between reward and motor learning. Yet no prior studies have established explicitly whether reward improves the rate or efficacy of robotics-assisted rehabilitation or produces neurophysiologic adaptations associated with motor learning. We conducted a 3 wk, 9-session clinical pilot with 10 people with chronic hemiparetic stroke, randomly assigned to train with an impedance-controlled ankle robot (anklebot) under either high reward (HR) or low reward conditions. The 1 h training sessions entailed playing a seated video game by moving the paretic ankle to hit moving onscreen targets with the anklebot only providing assistance as needed. Assessments included paretic ankle motor control, learning curves, electroencephalograpy (EEG) coherence and spectral power during unassisted trials, and gait function. While both groups exhibited changes in EEG, the HR group had faster learning curves (p = 0.05), smoother movements (p

Association of a peptoid ligand with the apical loop of pri-miR-21 inhibits cleavage by Drosha.

We have found a small molecule that specifically inhibits cleavage of a precursor to the oncogenic miRNA, miR-21, by the microprocessor complex of Drosha and DGCR8. We identified novel ligands for the apical loop of this precursor from a screen of 14,024 N-substituted oligoglycines (peptoids) in a microarray format. Eight distinct compounds with specific affinity were obtained, three having affinities for the targeted loop in the low micromolar range and greater than 15-fold discrimination against a closely related hairpin. One of these compounds completely inhibits microprocessor cleavage of a miR-21 primary transcript at concentrations at which cleavage of another miRNA primary transcript, pri-miR-16, is little affected. The apical loop of pri-miR-21, placed in the context of pri-miR-16, is sufficient for inhibition of microprocessor cleavage by the peptoid. This compound also inhibits cleavage of pri-miR-21 containing the pri-miR-16 apical loop, suggesting an additional site of association within pri-miR-21. The reported peptoid is the first example of a small molecule that inhibits microprocessor cleavage by binding to the apical loop of a pri-miRNA.

Brd4-mediated nuclear retention of the papillomavirus E2 protein contributes to its stabilization in host cells.

Papillomavirus E2 is a multifunctional viral protein that regulates many aspects of the viral life cycle including viral episome maintenance, transcriptional activation, and repression. E2 is degraded by the ubiquitin-proteasome pathway. Cellular bromodomain protein Brd4 has been implicated in the stabilization of the E2 protein. E2 normally shuttles between the cytoplasm and the nucleus. In this study, we demonstrate that E2 ubiquitylation mostly occurs in the cytoplasm. We also find that the interaction with Brd4 promotes nuclear retention of papillomavirus E2 proteins and contributes to their stabilization in the nucleus. Compared to wild type E2 proteins, nuclear-localization-defective mutants are rapidly degraded by the ubiquitin-proteasome pathway; however, co-expression of Brd4 redirects these mutants into the nucleus and significantly increases their stability. We further demonstrate that tethering E2 proteins to chromatin as either double-bromodomain fusion proteins or histone 2B (H2B) fusion proteins significantly stabilizes the E2 proteins. Our studies suggest that chromatin recruitment of the E2 protein via interaction with Brd4 prevents E2 ubiquitylation and proteasomal degradation in the cytoplasm, leading to its stabilization in the nucleus. These studies bring new insights for understanding Brd4-mediated E2 stabilization, and provide an additional mechanism by which the chromatin-associated Brd4 regulates E2 functions.