Early Successful Experiences of Surgical Conversion of Endoscopic Gastric Plication to Roux-en-Y Gastric Bypass

BACKGROUND

The primary obesity surgery endoluminal (POSE) procedure is an innovative incision-less endoscopic bariatric procedure that is increasingly used. However, variable weight loss response and recurrence post-endoscopic bariatric procedures have at times necessitated laparoscopic bariatric conversion. The safety and approach of conversion to laparoscopic sleeve gastrectomy (LSG) or Roux-en-Y gastric bypass (RYGB), however, have been an active point of discussion within revisional bariatric surgery.

METHODS

This retrospective review of four consecutive patients is the largest description of medium-term postoperative outcomes and technical highlights of a laparoscopic conversion of POSE to RYGB. Chart review was completed to evaluate patients' post-POSE clinical course and perioperative outcomes after surgical conversion.

RESULTS

Early data suggests varied weight loss trajectory with POSE and marked improvement in weight response after surgical conversion. Qualitative review reveals successful single-staged conversions contrary to previous smaller case series describing staged conversions involving endoscopic removal of plications followed by RYGB. Review additionally reveals key perioperative considerations for successful conversions to include intraoperative endoscopy, upper gastrointestinal fluoroscopic studies, and at times computed tomography. The latter study and laparoscopic view of the post-POSE stomach challenge the prior notion that distal POSE allows for easy revision to LSG.

CONCLUSIONS

Our case series underscores the complex multifactorial nature of metabolic disease and the increasing importance of a conscientious approach to conversion bariatric surgery as the adoption of POSE and the bariatric patient population continues to grow.

The SAGES MASTERS program bariatric surgery pathway selects 10 seminal publications on revisional bariatrics

BACKGROUND

The Society of American Gastrointestinal and Endoscopic Surgeons (SAGES) Masters Program designated bariatric surgery as a clinical pathway. Among the tiers of the Masters Program, revisional bariatric surgery is the highest tier of "mastery" within the pathway. This article presents the top 10 seminal studies representing the current landscape of revisional bariatrics.

METHODS

The literature was systematically searched and seminal articles designated by consensus agreement of the SAGES Metabolic and Bariatric Surgery committee using multiple criteria, including impact on the field, citation frequency, and expert opinion. Articles were reviewed by committee members and presented in summarized fashion.

RESULTS

The top 10 papers are presented in grouped thematic categories covering the early evolution of revisional bariatrics, changing criteria for reoperative bariatric surgery, divergence of revision versus conversion bariatric surgery, and recent technologic innovations in revisional bariatric surgery. Each summary is presented with expert appraisal and commentary.

CONCLUSION

These seminal papers represent a snapshot of the dynamic field of revisional bariatric surgery and emphasize the need to not only remain current with contemporary trends but also keep a patient-oriented perspective on patient and intervention selection for optimal success.

Esophageal and gastric malignancies after bariatric surgery: a retrospective global study

BACKGROUND

Bariatric surgery can influence the presentation, diagnosis, and management of gastrointestinal cancers. Esophagogastric (EG) malignancies in patients who have had a prior bariatric procedure have not been fully characterized.

OBJECTIVE

To characterize EG malignancies after bariatric procedures.

SETTING

University Hospital, United Kingdom.

METHODS

We performed a retrospective, multicenter observational study of patients with EG malignancies after bariatric surgery to characterize this condition.

RESULTS

This study includes 170 patients from 75 centers in 25 countries who underwent bariatric procedures between 1985 and 2020. At the time of the bariatric procedure, the mean age was 50.2 ± 10 years, and the mean weight 128.8 ± 28.9 kg. Women composed 57.3% (n = 98) of the population. Most (n = 64) patients underwent a Roux-en-Y gastric bypass (RYGB) followed by adjustable gastric band (AGB; n = 46) and sleeve gastrectomy (SG; n = 43). Time to cancer diagnosis after bariatric surgery was 9.5 ± 7.4 years, and mean weight at diagnosis was 87.4 ± 21.9 kg. The time lag was 5.9 ± 4.1 years after SG compared to 9.4 ± 7.1 years after RYGB and 10.5 ± 5.7 years after AGB. One third of patients presented with metastatic disease. The majority of tumors were adenocarcinoma (82.9%). Approximately 1 in 5 patients underwent palliative treatment from the outset. Time from diagnosis to mortality was under 1 year for most patients who died over the intervening period.

CONCLUSION

The Oesophago-Gastric Malignancies After Obesity/Bariatric Surgery study presents the largest series to date of patients developing EG malignancies after bariatric surgery and attempts to characterize this condition.

Robotic versus laparoscopic median arcuate ligament (MAL) release: a retrospective comparative study

BACKGROUND

Multiple retrospective studies have demonstrated the safety and feasibility of laparoscopic median arcuate ligament division with celiac neurolysis for the definitive management of median arcuate ligament syndrome (MALS). This study queries the clinical equipoise of robotic (RMALR) versus laparoscopic MAL release (LMALR) at a high-volume center.

METHODS

A retrospective analysis of consecutive 26 RMALR and 24 LMALR between March 2018 and August 2019 by a single surgeon at a quaternary academic institution was completed. Primary endpoint was postoperative decrease in celiac trunk expiratory peak systolic velocities (PSVs) measured by mesenteric duplex ultrasonography. Secondary outcomes included reported improvement in MALS-related clinical symptoms, distribution of first assistant seniority level, and involvement of second assistants in RMALR versus LMALR.

RESULTS

Mean operative times for LMALR and RMALR were 86 and 134 min, respectively (p < 0.0001). There were no open conversions and mean length of hospital stay was 1 day for both cohorts. Both groups provided an equally effective decrease in postoperative peak systolic velocities (PSVs) (LMALR p = 0.0011; RMALR p = 0.0022; LMALR vs. RMALR p = 0.7772). While RMALR had significantly higher reduction of chronic abdominal pain postoperatively, there were no significant differences in other postoperative symptom relief between groups. However, RMALR patients reported significant relief of postprandial abdominal pain (p < 0.0001) and chronic nausea (p = 0.0002). RMALR had significantly more junior first assistants (p = 0.0001) and less frequently required second assistants compared to LMALR (p = 0.0381).

CONCLUSIONS

In this study comparing RMALR to LMALR, postoperative chronic abdominal pain relief was significantly less in the former while other outcomes were equivalent. In comparison with LMALR, RMALR cases were associated with more junior first assistants, fewer second assistants, and longer operative times. Both approaches are safe and feasible for well-selected patients in experienced centers.

Bariatric Surgery is Safe for Patients After Recovery from COVID-19

BACKGROUND

Studies of patients who have undergone surgery while infected with COVID-19 have shown increased risks for adverse outcomes in both pulmonary complications and mortality. It has become clear that the risk of complications from perioperative COVID-19 infection must be weighed against the risk from delayed surgical treatment. Studies have also shown that prior bariatric surgery conveys protection against mortality from COVID-19 and that obesity is the biggest risk factor for mortality from COVID-19 infection in adults under 45 years of age. Studies in patients who have fully recovered from COVID-19 and underwent elective surgery have not become widely available yet.

OBJECTIVES

This multi-institutional case series is presented to highlight patients who developed COVID-19, fully recovered, and subsequently underwent elective bariatric surgery with 30-day outcomes available.

SETTING

Nine bariatric surgery centers located across the United States.

METHODS

This multicenter case series is a retrospective chart review of patients who developed COVID-19, recovered, and subsequently underwent bariatric surgery. Fifty-three patients are included, and 30-day morbidity and mortality were analyzed.

RESULTS

Thirty-day complications included esophageal spasm, dehydration, and ileus. There were no cardiovascular, venous thromboembolism (VTE) or respiratory events reported. There were no 30- day mortalities.

CONCLUSIONS

Bariatric surgery has been safely performed in patients who made a full recovery from COVID-19 without increased complications due to cardiovascular, pulmonary, venous thromboembolism, or increased mortality rates.

TLE4 Is a Critical Mediator of Osteoblast and Runx2-Dependent Bone Development

Healthy bone homeostasis hinges upon a delicate balance and regulation of multiple processes that contribute to bone development and metabolism. While examining hematopoietic regulation by Tle4, we have uncovered a previously unappreciated role of Tle4 on bone calcification using a novel Tle4 null mouse model. Given the significance of osteoblasts in both hematopoiesis and bone development, this study investigated how loss of Tle4 affects osteoblast function. We used dynamic bone formation parameters and microCT to characterize the adverse effects of Tle4 loss on bone development. We further demonstrated loss of Tle4 impacts expression of several key osteoblastogenic genes, including Runx2, Oc, and Ap, pointing toward a potential novel mechanism for Tle4-dependent regulation of mammalian bone development in collaboration with the RUNX family members.

Efficacy of Virtual Case-Based General Surgery Clerkship Curriculum During COVID-19 Distancing

OBJECTIVE

The COVID-19 pandemic created a paradigm shift in medical education with a reliance upon alternative teaching methods to deliver meaningful surgery clerkship content. This study examines the efficacy of a novel, case-based virtual surgery clerkship curriculum to determine its impact on student experience during quarantine.

STUDY DESIGN

Sixteen third-year medical students enrolled in the General Surgery clerkship between April through June 2020 during COVID-19 distancing at a quaternary medical center (Cleveland Clinic, Cleveland, OH) participated in this study. Course surveys, including a 10-question curriculum-based multiple-choice assessment, were administered before and after the clerkship. Analyses include student self-perception of readiness to see a surgical consult independently, students' interest in pursuing a General Surgery residency, and improvement of surgical knowledge.

RESULTS AND CONCLUSION

On a 5-point Likert scale, students felt significantly more assured in their ability to independently assess a surgical consult by the end of the course. Five (31%) students reported an influence of the curriculum on their personal interest in a career in General Surgery. Mean scores on the curriculum-based knowledge assessment increased. These findings highlight that a virtual platform can be a reliable alternative adjunct that delivers surgical content and positively impacts student experience.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s40670-020-01126-5.

Beyond Medical Knowledge and Patient Care: A Program Director's Perspective for the Role of General Surgery Subinternships

OBJECTIVE

Established primary goals of general surgery subinternships are improvement in patient care and medical knowledge. However, the secondary gains such as obtaining recommendation letters and forming relationships are apparent but poorly defined. We sought the opinion of general surgery program directors (PDs) on the secondary purposes of subinternships. Our aim is to aide mentors and students to optimize the subinternship experience relative to the residency application process.

DESIGN

A survey was administered in July 2019. This questionnaire consisted of 11 items and was broken down into 3 sections: demographics, PD perspective on the secondary goals of a general surgery subinternship, and the role of general surgery subinternships on the students' residency application.

SETTING

An online, national survey through the Association for Program Directors listserv.

PARTICIPANTS

United States general surgery PDs affiliated with the Association for Program Directors listserv.

RESULTS

Sixty-one PDs completed the survey from 42 (69%) academic and 14 (23%) community programs. The majority of PDs (n = 33, 54%) reported that assessment of a subintern's suitability for their residency was the most important secondary purpose. Furthermore, PDs (n = 24, 39%) valued a letter of recommendation from faculty the student worked with during a subinternship as the most important criteria in the interview selection process. Away rotations were perceived as of equal value to subinternships completed at the student's home institution. Overall, PD opinions were similar at academic and community programs.

CONCLUSIONS

Our study suggests subinternships significantly impact a student's application to general surgery residency, clarifying a secondary role for these rotations. Subinternships are important for PDs to assess a student for ranking at their program. All students should pursue a letter of recommendation from subinternship faculty, when possible, as they can heavily influence the interview selection process. Away rotations should only be recommended for those students who need to strengthen their application.

Effect modification of resident autonomy and seniority on perioperative outcomes in laparoscopic cholecystectomy

BACKGROUND

Resident operative involvement is an integral aspect of general surgery residency training. However, current data examining the effect of resident autonomy on perioperative outcomes remain limited.

METHODS

Patient and operator-specific data were collected from 344 adult laparoscopic cholecystectomies at a tertiary academic institution and its regional affiliates between 2018 and 2019. Multivariate modeling compared postoperative outcomes between cases completed with or without resident involvement and its effect modification by resident seniority and autonomy per Zwisch scale. Outcomes include 30-day postoperative complications, hospital readmission rate, and operative time.

RESULTS

Multivariate analysis revealed resident involvement in laparoscopic cholecystectomy did not significantly change odds of 30-day postoperative complications (OR 2.52, p = 0.185, 95% CI 0.64-9.92) or hospital readmission (OR 1.61, p = 0.538, 95% CI 0.36-7.23). Operative time is significantly increased compared to faculty-only cases (IRR 1.37, p < 0.001, 95% CI 1.26-1.48). While accounting for case difficulty and resident performance evaluated by SIMPL criteria, stratification by resident autonomy measured by Zwisch scale or seniority reveal no effect modification on 30-day postoperative complications, readmissions, or operative time. The effect of resident involvement on longer relative rates of operative time loses its significance in supervision-only cases (IRR 1.18, p = 0.069, 95% CI 0.99-1.41).

CONCLUSION

While resident involvement and autonomy are associated with significantly longer operative times in laparoscopic cholecystectomy, their lack of significant effect on postoperative outcomes argues strongly for continued resident involvement and supervised operative independence.

Polyamine patterns in plasma of patients with systemic lupus erythematosus and fever

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease with various clinical manifestations and serologic markers. In this study, we analyzed nine polyamine (PA) profiles of plasma from patients with SLE and healthy controls (HCs), and the relationship between the PA profiles and disease activity. PA alterations in plasma of 44 patients with SLE and fever were investigated using gas chromatography mass spectrometry (GC-MS) in selected ion monitoring mode using N-ethoxycarbonyl/ N-pentafluoropropionyl derivatives, and compared with those of 43 HCs. Patients with SLE and HCs showed differences in five of nine PA profiles. Among five changed PA levels, four PAs, namely N¹-acetylcadaverine, spermidine, N¹-acetylspermidine, and spermine, were dramatically decreased. However, the level of cadaverine was increased in patients with SLE. In the partial correlation with PA profiles and disease activity markers of SLE, several disease activity markers and nutritional markers were correlated with cadaverine, spermidine, and N ⁸-acetylspermidine. Thus, our results provide a comprehensive understanding of the relationship between PA metabolomics and disease activity markers in patients with SLE.

TLE4 regulation of wnt-mediated inflammation underlies its role as a tumor suppressor in myeloid leukemia

The presence of AML1-ETO (RUNX1-CBF2T1), a fusion oncoprotein resulting from a t(8;21) chromosomal translocation, has been implicated as a necessary but insufficient event in the development of a subset of acute myeloid leukemias (AML). While AML1-ETO prolongs survival and inhibits differentiation of hematopoietic stem cells (HSC), other contributory events are needed for cell proliferation and leukemogenesis. We have postulated that specific tumor suppressor genes keep the leukemic potential of AML1-ETO in check. In studying del(9q), one of the most common concomitant chromosomal abnormalities with t(8;21), we identified the loss of an apparent tumor suppressor, TLE4, that appears to cooperate with AML1-ETO to confer a leukemic phenotype. This study sought to identify the molecular basis of this cooperation. We show that the loss of TLE4 confers proliferative advantage to leukemic cells, simultaneous with an upregulation of a pro- inflammatory signature mediated through aberrant increases in Wnt signaling activity. We further demonstrate that inhibition of cyclooxygenase (COX) activity partly reverses the pro-leukemic phenotype due to TLE4 knockdown, pointing towards a novel therapeutic approach for myeloid leukemia.

The corepressor Tle4 is a novel regulator of murine hematopoiesis and bone development

Hematopoiesis is a complex process that relies on various cell types, signaling pathways, transcription factors and a specific niche. The integration of these various components is of critical importance to normal blood development, as deregulation of these may lead to bone marrow failure or malignancy. Tle4, a transcriptional corepressor, acts as a tumor suppressor gene in a subset of acute myeloid leukemia, yet little is known about its function in normal and malignant hematopoiesis or in mammalian development. We report here that Tle4 knockout mice are runted and die at around four weeks with defects in bone development and BM aplasia. By two weeks of age, Tle4 knockout mice exhibit leukocytopenia, B cell lymphopenia, and significant reductions in hematopoietic stem and progenitor cells. Tle4 deficient hematopoietic stem cells are intrinsically defective in B lymphopoiesis and exhaust upon stress, such as serial transplantation. In the absence of Tle4 there is a profound decrease in bone mineralization. In addition, Tle4 knockout stromal cells are defective at maintaining wild-type hematopoietic stem cell function in vitro. In summary, we illustrate a novel and essential role for Tle4 in the extrinsic and intrinsic regulation of hematopoiesis and in bone development.

Highly optimized DNA vaccine targeting human telomerase reverse transcriptase stimulates potent antitumor immunity

High levels of human telomerase reverse transcriptase (hTERT) are detected in more than 85% of human cancers. Immunologic analysis supports that hTERT is a widely applicable target recognized by T cells and can be potentially studied as a broad cancer immunotherapeutic, or a unique line of defense against tumor recurrence. There remains an urgent need to develop more potent hTERT vaccines. Here, a synthetic highly optimized full-length hTERT DNA vaccine (phTERT) was designed and the induced immunity was examined in mice and non-human primates (NHP). When delivered by electroporation, phTERT elicited strong, broad hTERT-specific CD8 T-cell responses including induction of T cells expressing CD107a, IFN-γ, and TNF-α in mice. The ability of phTERT to overcome tolerance was evaluated in an NHP model, whose TERT is 96% homologous to that of hTERT. Immunized monkeys exhibited robust [average 1,834 spot forming unit (SFU)/10(6) peripheral blood mononuclear cells (PBMC)], diverse (multiple immunodominant epitopes) IFN-γ responses and antigen-specific perforin release (average 332 SFU/10(6) PBMCs), suggesting that phTERT breaks tolerance and induces potent cytotoxic responses in this human-relevant model. Moreover, in an HPV16-associated tumor model, vaccination of phTERT slows tumor growth and improves survival rate in both prophylactic and therapeutic studies. Finally, in vivo cytotoxicity assay confirmed that phTERT-induced CD8 T cells exhibited specific cytotoxic T lymphocyte (CTL) activity, capable of eliminating hTERT-pulsed target cells. These findings support that this synthetic electroporation-delivered DNA phTERT may have a role as a broad therapeutic cancer vaccine candidate.

Induction of robust cellular immunity against HPV6 and HPV11 in mice by DNA vaccine encoding for E6/E7 antigen

Due to the strong relationship between the Human Papillomavirus (HPV) "high-risk" subtypes and cervical cancers, most HPV-related studies have been focusing on the "high-risk" HPV subtypes 16 and 18. However, it has been suggested that the "low-risk" subtypes of HPV, HPV6 and HPV11, are the major cause of recurrent respiratory papillomatosis and genital warts. In addition, HPV 6 and 11 are also associated with otolaryngologic malignancies, carcinoma of the lung, tonsil, larynx and low-grade cervical lesions. Therefore, development of HPV therapeutic vaccines targeting on subtypes 6 and 11 E6 or E7 are in great need. In this report, we describe two novel engineered DNA vaccines that encode HPV 6 and 11 consensus E6/E7 fusion proteins (p6E6E7 and p11E6E7) by utilizing a multi-phase strategy. Briefly, after generating consensus sequences, several modifications were performed to increase the expression of both constructs, including codon/RNA optimization, addition of a Kozak sequence and a highly efficient leader sequence. An endoproteolytic cleavage site was also introduced between E6 and E7 protein for proper protein folding and for better CTL processing. The expressions of both constructs were confirmed by western blot analysis and immunofluorescence assay. Vaccination with these DNA vaccines could elicit robust cellular immune responses. The epitope mapping assay was performed to further characterize the cellular immune responses induced by p6E6E7 and p11E6E7. The HPV 6 and 11 E6 or E7-specific immunodominant and subdominant epitopes were verified, respectively. The intracellular cytokine staining revealed that the magnitude of IFN-γ and TNF-α secretion in antigen-specific CD8(+) cells was significantly enhanced, indicating that the immune responses elicited by p6E6E7 and p11E6E7 was heavily skewed toward driving CD8(+) T cells. Such DNA immunogens are interesting candidates for further studies on HPV 6 and 11-associated diseases.

Clinical applications of DNA vaccines: current progress

It was discovered almost 20 years ago that plasmid DNA, when injected into the skin or muscle of mice, could induce immune responses to encoded antigens. Since that time, there has since been much progress in understanding the basic biology behind this deceptively simple vaccine platform and much technological advancement to enhance immune potency. Among these advancements are improved formulations and improved physical methods of delivery, which increase the uptake of vaccine plasmids by cells; optimization of vaccine vectors and encoded antigens; and the development of novel formulations and adjuvants to augment and direct the host immune response. The ability of the current, or second-generation, DNA vaccines to induce more-potent cellular and humoral responses opens up this platform to be examined in both preventative and therapeutic arenas. This review focuses on these advances and discusses both preventive and immunotherapeutic clinical applications.

MOM-4, a MAP kinase kinase kinase-related protein, activates WRM-1/LIT-1 kinase to transduce anterior/posterior polarity signals in C. elegans

In C. elegans, a Wnt/WG-like signaling pathway down-regulates the TCF/LEF-related protein, POP-1, to specify posterior cell fates. Effectors of this signaling pathway include a beta-catenin homolog, WRM-1, and a conserved protein kinase, LIT-1. WRM-1 and LIT-1 form a kinase complex that can directly phosphorylate POP-1, but how signaling activates WRM-1/LIT-1 kinase is not yet known. Here we show that mom-4, a genetically defined effector of polarity signaling, encodes a MAP kinase kinase kinase-related protein that stimulates the WRM-1/LIT-1-dependent phosphorylation of POP-1. LIT-1 kinase activity requires a conserved residue analogous to an activating phosphorylation site in other kinases, including MAP kinases. These findings suggest that anterior/posterior polarity signaling in C. elegans may involve a MAP kinase-like signaling mechanism.

WRM-1 activates the LIT-1 protein kinase to transduce anterior/posterior polarity signals in C. elegans

During C. elegans development, Wnt/WG signaling is required for differences in cell fate between sister cells born from anterior/posterior divisions. A beta-catenin-related gene, wrm-1, and the lit-1 gene are effectors of this signaling pathway and appear to downregulate the activity of POP-1, a TCF/LEF-related protein, in posterior daughter cells. We show here that lit-1 encodes a serine/threonine protein kinase homolog related to the Drosophila tissue polarity protein Nemo. We demonstrate that the WRM-1 protein binds to LIT-1 in vivo and that WRM-1 can activate the LIT-1 protein kinase when coexpressed in vertebrate tissue culture cells. This activation leads to phosphorylation of POP-1 and to apparent changes in its subcellular localization. Our findings provide evidence for novel regulatory avenues for an evolutionarily conserved Wnt/WG signaling pathway.

Transcriptional repression by the Caenorhabditis elegans germ-line protein PIE-1

In the early Caenorhabditis elegans embryo, maternally expressed PIE-1 protein is required in germ-line blastomeres to inhibit somatic differentiation, maintain an absence of mRNA transcription, and block phosphorylation of the RNA polymerase II large subunit (Pol II) carboxy-terminal domain (CTD). We have determined that PIE-1 can function as a transcriptional repressor in cell culture assays. By fusing PIE-1 sequences to the yeast GAL4 DNA-binding domain, we have identified a PIE-1 repression domain that appears to inhibit the transcriptional machinery directly. A sequence element that is required for this repressor activity is similar to the Pol II CTD heptapeptide repeat, suggesting that the PIE-1 repression domain might target a protein complex that can bind the CTD. An alteration of this sequence element that blocks repression also impairs the ability of a transgene to rescue a pie-1 mutation, suggesting that this repressor activity may be important for PIE-1 function in vivo.

Transcription factor AP-2 controls transcription of the human transforming growth factor-alpha gene

The epidermal growth factor receptor is vital for normal development and plays a role in oncogenesis. The level of activation of this receptor by transforming growth factor-alpha (TGF-alpha) is controlled, in part, by the rate of transcription of the TGF-alpha gene. In the characterization of the proximal TGF-alpha promoter by DNase I footprinting, a 43-base pair element (-88 to -130 relative to the transcription start site), designated TalphaRE I, was found that was specifically protected by nuclear proteins from human mammary carcinoma MDA468 cells. TalphaRE I was essential for the maximal expression of the TGF-alpha gene as indicated by deletion and mutagenesis analyses. TalphaRE I consists of two cis-acting elements, a proximal regulatory element (PRE, -89 to -103) and a distal regulatory element (DRE, -121 to -128). Both elements were able to form specific complexes with protein from MDA468 cell nuclear extracts and are necessary for the full activity of the entire 1.1-kilobase pair TGF-alpha promoter. Competition and antibody studies determined that the DRE contains a binding site for the transcription factor AP-2, while the protein that binds to the PRE has yet to be identified. When linked upstream to the heterologous herpes simplex thymidine kinase promoter, the TalphaRE I enhanced transcription up to 11-fold in MDA468 cells. Cotransfection of an AP-2 expression vector was able to activate transcription from the TalphaREI-TK construct in a DRE-dependent manner. These results further our understanding of how TGF-alpha transcription is regulated.

Identification of subunits of the anaphase-promoting complex of Saccharomyces cerevisiae

Entry into anaphase and proteolysis of B-type cyclins depend on a complex containing the tetratricopeptide repeat proteins Cdc16p, Cdc23p, and Cdc27p. This particle, called the anaphase-promoting complex (APC) or cyclosome, functions as a cell cycle-regulated ubiquitin-protein ligase. Two additional subunits of the budding yeast APC were identified: The largest subunit, encoded by the APC1 gene, is conserved between fungi and vertebrates and shows similarity to BIMEp from Aspergillus nidulans. A small heat-inducible subunit is encoded by the CDC26 gene. The yeast APC is a 36S particle that contains at least seven different proteins.

Asymmetric accumulation of Ash1p in postanaphase nuclei depends on a myosin and restricts yeast mating-type switching to mother cells

Cell division in haploid yeast gives rise to a "mother" cell capable of mating-type switching and a "daughter" cell that is not. Switching is initiated by the HO endonuclease, whose gene is only transcribed in cells that have previously given birth to a bud (mother cells). HO expression depends on a minimyosin, She1p/Myo4p, which accumulates preferentially in growing buds. We describe a gene, ASH1, that is necessary to repress HO in daughters. ASH1 encodes a zinc finger protein whose preferential accumulation in daughter cell nuclei at the end of anaphase depends on She1p/Myo4p. The greater abundance of Ash1p in daughter cells is responsible for restricting HO expression to mother cells.

p53 stimulates transcription from the human transforming growth factor alpha promoter: a potential growth-stimulatory role for p53

Physical and chemical agents can damage the genome. Part of the protective response to this damage is the increased expression of p53. p53, a transcription factor, controls the expression of genes, leading to cell cycle arrest and apoptosis. Another protective mechanism is the proliferative response required to replace the damaged cells. This proliferation is likely to be signaled by growth factors. In this communication, we show that the transforming growth factor alpha (TGF-alpha) gene is a direct target for p53-mediated transcriptional activation. In a stable cell line containing an inducible p53 construct, p53 induction leads to a threefold accumulation of the native TGF-alpha mRNA. IN cotransfection assays using a TGF-alpha promoter reporter construct, we show that expression of wild-type but not mutant p53 increases transcriptional activity of the TGF-alpha promoter by approximately 2.5-fold. In vitro, wild-type p53 binds to a consensus binding site found in the proximal portion of the promoter, and this sequence is necessary for the p53 transcriptional response. Furthermore, this element confers p53 induction to the otherwise nonresponsive adenovirus major late promoter. In addition to these results, we found that the TGF-alpha promoter contains a nonconsensus but functional TATA box-binding protein-binding site approximately 30 bp upstream of the transcription start site. Although p53 can repress transcription from promoters containing a TATA box, the nonconsensus TGF-alpha TATA motif is resistant to this effect. On the basis of these results, we propose that p53 may play a dual role, which includes both the elimination of irreparably genetically damage cells and the proliferative response necessary for their replacement, in the response to physical-chemical damage.

Identification and characterization of the human transforming growth factor-alpha initiator

Eukaryotic transcription requires promoter proximal elements. For class II promoters, two such elements are the TATA box and the initiator. The promoter for the human transforming growth factor-alpha (TGF alpha) gene has been shown to lack a TATA box, yet initiate transcription at a unique site. We have identified an approximately 13-basepair sequence between -5 and +8 as a new promoter element. We call this element the TGF alpha initiator based on the following observations: 1) it is located at the transcription initiation site; 2) the promoter activity is largely reduced by either deletion or mutation of the element; and 3) mutations result in initiation upstream of the authentic start site; the TGF alpha initiator directs site-specific initiation. An electrophoretic mobility shift assay demonstrated that a protein(s) in nuclear extracts forms complexes with the TGF alpha initiator. This interaction is sequence specific and depends on nucleotides that are critical for the promoter activity in vivo. Two polypeptides, 105 and 95 kilodaltons, were detected by Southwestern blot analysis on the basis that they specifically interact with the TGF alpha initiator. The larger polypeptide, TIBP-1, was subsequently purified by a matrix-immobilized TGF alpha initiator sequence and was shown to possess the TGF alpha initiator-specific mobility shift activity and an ability to interact with the initiator when immobilized on a membrane. In summary, we identified and characterized the TGF alpha initiator, a proximal element that is important for the accurate transcription of the TGF alpha gene, and the 105-kilodalton protein that interacts with this element.(ABSTRACT TRUNCATED AT 250 WORDS)

5-Azacytidine treatment of HA-A melanoma cells induces Sp1 activity and concomitant transforming growth factor alpha expression

Evidence indicates DNA methylation as a part of the regulatory machinery controlling mammalian gene expression. The human melanoma cell line HA-A expresses low levels of transforming growth factor alpha (TGF-alpha). TGF-alpha mRNA accumulated, however, in response to DNA demethylation induced by a nucleoside analog, 5-azacytidine (5-azaC). The importance of DNA methylation in the TGF-alpha promoter region was examined by a transient transfection assay with luciferase reporter plasmids containing a portion of the TGF-alpha promoter. 5-azaC treatment of HA-A cells before the transfection caused a significant increase in the luciferase activity. Since input plasmids were confirmed to remain unmethylated, DNA demethylation of the TGF-alpha promoter itself does not account for the observed increase in TGF-alpha mRNA. Using an electrophoretic mobility shift assay, enhanced formation of protein-TGF-alpha promoter complex was detected in response to 5-azaC treatment. This 5-azaC-induced complex was shown to contain the transcription factor Sp1 by the following criteria: the protein-DNA complex formed on the TGF-alpha promoter contained immunoreactive Sp1; the mobility of the complex in an electrophoretic mobility shift assay was similar to that formed by recombinant Sp1; and DNase I footprinting analysis demonstrated that the 5-azaC-induced complex produced a footprint on the TGF-alpha promoter identical to that of authentic Sp1. These observations suggest that 5-azaC induces TGF-alpha expression by augmenting the Sp1 activity. However, neither the Sp1 mRNA nor its protein was induced by 5-azaC. These results suggest that in HA-A cells, TGF-alpha expression is down-modulated by DNA methylation. In addition, this process may involve the specific regulation of Sp1 activity without altering the amount of the transcription factor.

Transcriptional regulation of the human transforming growth factor-alpha gene

We and others have previously reported that transforming growth factor-alpha (TGF alpha) expression is hormonally responsive and its expression is coregulated with that of its receptor [the epidermal growth factor (EGF) receptor]. The 5'-flanking region of the TGF alpha gene was characterized to determine whether it could confer hormone responsiveness to a reporter gene (luciferase) in human mammary carcinoma cells (MDA468). This segment of the gene is GC rich and contains an element strikingly similar to the core element of the EGF receptor gene that has been shown to mediate both basal and hormone-stimulated expression of the EGF receptor. We now report that a 313-basepair (bp) proximal element of the TGF alpha 5'-flanking region (-373 to -59 relative to the TGF alpha translation start codon) is capable of conferring responses to phorbol ester and EGF. This gene segment does not contain the EGF receptor gene homolog or potential AP-2-binding sites, suggesting that these elements are not necessary for basal and EGF- or phorbol ester-responsive TGF alpha gene expression. This 313-bp proximal element also confers proper transcriptional initiation to the chimeric TGF alpha-luciferase reporter construct, indicating it is the TGF alpha promoter. A 1.1-kilobase segment of the TGF alpha 5'-flanking region also confers retinoic acid, thyroid hormone, and glucocorticoid responsiveness despite the absence of recognizable steroid hormone receptor-binding sites. These hormones stimulate reporter expression 1.5- to 2-fold in a dose-dependent manner. Extension of the 5'-flanking region to -3500 results in marked suppression of reporter gene expression. These results indicate that the TGF alpha gene 5'-flanking sequence contains the elements responsible for hormonal responsiveness of this gene and that these elements are distinct from those that regulate the expression of the EGF receptor gene.