The CDK4/6 inhibitor Palbociclib synergizes with ATRA to induce differentiation in AML.

Differentiation therapy based on ATRA almost cured acute promyelocytic leukemia (APL). However, it is disappointing that ATRA is not effective against other acute myeloid leukemia (AML) subtypes. Developing new and effective anti-AML therapies that promote leukemia differentiation is necessary. The CDK4/6-cyclin D pathway is a key initiator of the G1/S phase transition, which determines cell fate. Herein, we investigated whether the CDK4/6 inhibitor palbociclib would synergize with ATRA to promote leukemia differentiation in vitro and in vivo. Our findings revealed that CDK4/6-cyclin D pathway genes were aberrantly expressed in AML, and we observed that palbociclib sensitized AML cells to ATRA-induced morphologic, biochemical, and functional changes indicative of myeloid differentiation. The combination of palbociclib and ATRA attenuated AML cell expansion in vivo. These enhanced differentiation effects may be associated with the regulation of transcription factors, including RARα, E2F1, and STAT1. Overall, our findings demonstrate that CDK4/6 inhibition sensitizes AML cells to ATRA and could guide the development of novel therapeutic strategies for AML patients.

Facile Construction of Benzo[d][1,3]oxazocine: Reductive Radical Dearomatization of N-Alkyl Quinoline Quaternary Ammonium Salts.

Reductive radical dearomatization N-alkyl quinoline quaternary ammonium salts to synthesize structurally complex and challenging polysubstituted benzo[d][1,3]oxazocines was first reported. The mechanism showed various allyl alcohols can be converted into alkyl radicals under reduction conditions of iron/silane. These radicals then nucleophilically attack the C4 site of N-alkyl quinoline quaternary ammonium salts, and intramolecular cyclization of the resulting intermediate generates the target product. This method not only produced a series of novel polysubstituted benzo[d][1,3]oxazocines but also prepared polycyclic benzo[d][1,3]oxazocines. Finally, this strategy made up for the lack of reductive radical reports on N-alkylquinolinium salts and also had the advantages of mild reaction conditions, wide substrate range, and novel product structure.

Genome-wide identification of the melon (Cucumis melo L.) response regulator gene family and functional analysis of CmRR6 and CmPRR3 in response to cold stress.

The response regulator (RR) gene family play crucial roles in cytokinin signal transduction, plant development, and resistance to abiotic stress. However, there are no reports on the identification and functional characterization of RR genes in melon. In this study, a total of 18 CmRRs were identified and classified into type A, type B, and clock PRRs, based on phylogenetic analysis. Most of the CmRRs displayed tissue-specific expression patterns, and some were induced by cold stress according to two RNA-seq datasets. The expression patterns of CmRR2/6/11/15 and CmPRR2/3 under cold treatment were confirmed by qRT-PCR. Subcellular localization assays indicated that CmRR6 and CmPRR3 were primarily localized in the nucleus and chloroplast. Furthermore, when either CmRR6 or CmPRR3 were silenced using tobacco ringspot virus (TRSV), the cold tolerance of the virus-induced gene silencing (VIGS) melon plants were significantly enhanced, as evidenced by measurements of chlorophyll fluorescence, ion leakage, reactive oxygen, proline, and malondialdehyde levels. Additionally, the expression levels of CmCBF1, CmCBF2, and CmCBF3 were significantly increased in CmRR6-silenced and CmPRR3-silenced plants under cold treatment. Our findings suggest that CmRRs contribute to cold stress responses and provide new insights for further pursuing the molecular mechanisms underlying CmRRs-mediated cold tolerance in melon.

Access to 5-Methyl-5H-naphtho[2,3-c]carbazole-8,13-dione Derivatives via Copper-Catalyzed Intramolecular Isomerization.

Carbazole-fused quinones are important compounds for their potential pharmacological activities and photophysical properties. Here, a novel copper-catalyzed intramolecular isomerization process to access a new class of naphtho[2,3-c]carbazole-8,13-dione derivatives via a furan isomerization/γ-H elimination and ß-C elimination/6π-electrocyclization/aromatization cascade is reported. Furthermore, the preliminary photophysical properties of the functional 5-methyl-5H-naphtho[2,3-c]carbazole-8,13-dione derivatives have been studied.

An Intrabody against B-Cell Receptor-Associated Protein 31 (BAP31) Suppresses the Glycosylation of the Epithelial Cell-Adhesion Molecule (EpCAM) via Affecting the Formation of the Sec61-Translocon-Associated Protein (TRAP) Complex.

The epithelial cell-adhesion molecule (EpCAM) is hyperglycosylated in carcinoma tissue and the oncogenic function of EpCAM primarily depends on the degree of glycosylation. Inhibiting EpCAM glycosylation is expected to have an inhibitory effect on cancer. We analyzed the relationship of BAP31 with 84 kinds of tumor-associated antigens and found that BAP31 is positively correlated with the protein level of EpCAM. Triple mutations of EpCAM N76/111/198A, which are no longer modified by glycosylation, were constructed to determine whether BAP31 has an effect on the glycosylation of EpCAM. Plasmids containing different C-termini of BAP31 were constructed to identify the regions of BAP31 that affects EpCAM glycosylation. Antibodies against BAP31 (165-205) were screened from a human phage single-domain antibody library and the effect of the antibody (VH-F12) on EpCAM glycosylation and anticancer was investigated. BAP31 increases protein levels of EpCAM by promoting its glycosylation. The amino acid region from 165 to 205 in BAP31 plays an important role in regulating the glycosylation of EpCAM. The antibody VH-F12 significantly inhibited glycosylation of EpCAM which, subsequently, reduced the adhesion of gastric cancer cells, inducing cytotoxic autophagy, inhibiting the AKT-PI3K-mTOR signaling pathway, and, finally, resulting in proliferation inhibition both in vitro and in vivo. Finally, we clarified that BAP31 plays a key role in promoting N-glycosylation of EpCAM by affecting the Sec61 translocation channels. Altogether, these data implied that BAP31 regulates the N-glycosylation of EpCAM and may represent a potential therapeutic target for cancer therapy.

Underwater Target Detection Based on Parallel High-Resolution Networks.

A parallel high-resolution underwater target detection network is proposed to address the problems of complex underwater scenes and limited target feature extraction capability. First, a high-resolution network (HRNet), a lighter high-resolution human posture estimation network, is used to improve the target feature representation and effectively reduce the semantic information lost in the image during sampling. Then, the attention module (A-CBAM) is improved to capture complex feature distributions by modeling the two-dimensional space in the activation function stage through the introduction of the flexible rectified linear units (FReLU) activation function to achieve pixel-level spatial information modeling capability. Feature enhancement in the spatial and channel dimensions is performed to improve understanding of fuzzy targets and small target objects and to better capture irregular and detailed object layouts. Finally, a receptive field augmentation module (RFAM) is constructed to obtain sufficient semantic information and rich detail information to further enhance the robustness and discrimination of features and improve the detection capability of the model for multi-scale underwater targets. Experimental results show that the method achieves 81.17%, 77.02%, and 82.9% mean average precision (mAP) on three publicly available datasets, specifically underwater robot professional contest (URPC2020, URPC2018) and pattern analysis, statistical modeling, and computational learning visual object classes (PASCAL VOC2007), respectively, demonstrating the effectiveness of the proposed network.

Clinical implications of aberrant PD-1 expression for acute leukemia prognosis.

BACKGROUND: Acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) are the most common types of leukemia in adults with an overall poor prognosis. PD-1 alone or combined with other immune checkpoint blockade is a promising research direction for the treatment of acute leukemia (AL) patients. However, clinical Implications of aberrant PD-1 expression in peripheral CD4+ and CD8+ T lymphocytes of AML and ALL patients in assessing the prognosis of diseases, remains inconclusive. METHODS: In the present study, we used flow cytometry to evaluate PD-1 expression on the surface of CD4+ and CD8+ T lymphocytes in the peripheral circulation of AML and ALL patients and its clinical significance. A total of 53 AML patients, 44 ALL patients and 28 healthy controls were enrolled in this study and peripheral blood specimens were detected by flow cytometry. RESULTS: Our results indicated that percentages of CD4+ PD1+ and CD8+ PD1+ T lymphocytes in newly diagnosed and non-remission groups were significantly higher than healthy control both in AML and ALL patients. The high level of CD4+ PD1+ and CD8+ PD1+ T lymphocytes were respectively poor prognostic indicators of AML patients and ALL patients but had no significant correlation with most common clinical risks. CONCLUSIONS: Our findings show that aberrant PD-1 expression correlates with the prognosis of AL patient and may thus serve as poor prognostic indicators. Immunotherapy using PD-1 inhibitors may be a promising strategy for AML and ALL patients with peripheral circulating CD4+ PD1+ and CD8+ PD1+ T lymphocytes positively expressed, respectively.

Knockdown of BAP31 Downregulates Galectin-3 to Inhibit the Wnt/ß-Catenin Signaling Pathway to Modulate 5-FU Chemosensitivity and Cancer Stemness in Colorectal Cancer.

Increased stemness is causally linked to the development of chemoresistance in cancers. B-cell receptor-associated protein 31 (BAP31) has been identified to play an oncogenic role in many types of cancer. However, the role of BAP31 in 5-fluorouracil (5-FU) chemosensitivity and stemness of colorectal cancer (CRC) is still unknown. The aim of this study was to investigate the biological function and molecular mechanism of BAP31 in regulating 5-FU chemosensitivity and stemness. The correlation between BAP31 expression and 5-FU chemosensitivity was examined using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide and colony formation assays. Cancer stemness was analyzed using tumor sphere formation and Western blot assays. Western blot and immunofluorescence analyses of the knockdown cell lines were performed to explore the possible mechanisms. Finally, we investigated the function of BAP31 by constructing xenograft nude mouse models in vivo. In this study, we demonstrated that BAP31 was increased in CRC cells, and knockdown of BAP31 reduced the half maximal inhibitory concentration (IC50) of 5-FU, while this effect was reversed by overexpression of BAP31. In addition, knockdown of BAP31 substantially reduced the stemness of CRC cells in vitro. Consistently, knockdown of BAP31 significantly suppressed the tumorigenicity and stemness of CRC in vivo. The functional study further suggested that knockdown of BAP31 downregulated galectin-3 to inhibit the accumulation of ß-catenin, which in turn repressed the transcription of downstream target genes (c-MYC, SOX2) of the Wnt/ß-catenin signaling pathway. Knockdown of BAP31 reduced stemness by inhibiting the Wnt/ß-catenin signaling pathway to increase 5-FU chemosensitivity. Importantly, intrabodies against BAP31 suppressed tumor growth and enhanced the antitumor effects of 5-FU in vivo. Therefore, using intrabodies against BAP31 may be a strategy for improving the antitumor effect of 5-FU in CRC.

Hybridized Triboelectric-Electromagnetic Aeolian Vibration Generator as a Self-Powered System for Efficient Vibration Energy Harvesting and Vibration Online Monitoring of Transmission Lines.

In this work, based on the triboelectric-electromagnetic working principle, a comprehensive strategy appropriately hybridizes a multilayered elastic structure TENG (ME-TENG) and a double-electromagnetic generator (EMG) for efficient aeolian vibration energy harvesting and vibration state monitoring. The ME-TENG with the feature of elasticity is integrated with a movable plate embedded with a magnet as the counterweight, which acts as a spring-like mass system in response to external vibration excitation, making the inseparable integrity of the TENG and EMG. The basic hybridized triboelectric-electromagnetic aeolian vibration generator (HAVG) consisting of ME-TENG and double-EMGs in terms of structural parameters and response characteristics is first optimized and discussed, thereby the efficient vibration energy harvesting and effective vibration state response can be further improved through the mutual complementarity of TENG and EMG. Furthermore, the self-powered capacity of the HAVG in terms of LED arrays and a wireless ambient temperature and humidity monitoring system is verified through the hybrid charging strategy of TENG and EMG modules and the combination of HVAG and energy management circuits, benefiting from the sophisticated-designed structure and excellent output performance of the HAVG. Importantly, a self-powered aeolian vibration monitoring system is established and demonstrated for vibration-state sensing and abnormal vibration alarm. This work demonstrates a novel strategy for energy harvesting and state sensing of overhead transmission line aeolian vibration, which not only reveals TENG-EMG promising potential for energy harvesting for aeolian vibration, but also provides valuable guidance for the construction of a self-powered online-monitoring system for transmission lines.

Identification of candidate genes that regulate the trade-off between seedling cold tolerance and fruit quality in melon (Cucumis melo L.).

Trade-offs between survival and growth are widely observed in plants. Melon is an annual, trailing herb that produces economically valuable fruits that are traditionally cultivated in early spring in China. Melon seedlings are sensitive to low temperatures, and thus usually suffer from cold stress during the early growth period. However, little is known about the mechanism behind the trade-offs between seedling cold tolerance and fruit quality in melon. In this study, a total of 31 primary metabolites were detected from the mature fruits of eight melon lines that differ with respect to seedling cold tolerance; these included 12 amino acids, 10 organic acids, and 9 soluble sugars. Our results showed that concentrations of most of the primary metabolites in the cold-resistant melons were generally lower than in the cold-sensitive melons; the greatest difference in metabolite levels was observed between the cold-resistant line H581 and the moderately cold-resistant line HH09. The metabolite and transcriptome data for these two lines were then subjected to weighted correlation network analysis, resulting in the identification of five key candidate genes underlying the balancing between seedling cold tolerance and fruit quality. Among these genes, CmEAF7 might play multiple roles in regulating chloroplast development, photosynthesis, and the ABA pathway. Furthermore, multi-method functional analysis showed that CmEAF7 can certainly improve both seedling cold tolerance and fruit quality in melon. Our study identified an agriculturally important gene, CmEAF7, and provides a new insight into breeding methods to develop melon cultivars with seedling cold tolerance and high fruit quality.

Copper(I)-Mediated Divergent Synthesis of Pyrroquinone Derivatives and 2-Halo-3-amino-1,4-quinones.

A divergent transformation of 2-amino-1,4-quinones for the synthesis of pyrroquinone derivatives and 2-halo-3-amino-1,4-quinones was disclosed. The mechanistic study showed that both the tandem cyclization and halogenation involved a Cu(I)-catalyzed oxidative radical process. This protocol not only constructed a series of novel pyrroquinone derivatives with high atom economy but also provided a new method of halogenation via directed C(sp2)-H functionalization with CuX (X = I, Br, Cl) serving as the X (X = I, Br, Cl) source.

Long-term sciatic nerve block led by a supramolecular arrangement of self-delivery local anesthetic nano systems.

Classical local anesthetics are unsuitable to treat regional pain lasting several days due to their limited duration and systemic toxicity. Self-delivery nano systems without excipients were designed for long-term sensory blocks. 1a self-assembled into different vehicles with different fractions of intermolecular π-π stacking, transported itself into nerve cells, and released single molecules slowly to achieve long-term duration for rats' sciatic nerve block for 11.6 h in water, 12.1 h in water with CO2 and 3.4 h in NS (normal saline). After the counter ions were changed to SO42-, 1e can self-assemble into vesicles and prolong the duration to 43.2 h, which was much longer than the 3.8 h led by (s)-bupivacaine hydrocloride (0.75%). This was mainly caused by the enhancement of self-release and counter ion exchange inside nerve cells, which were affected by the gemini surfactant structure, pKa of the counter ions and π-π stacking interactions.

Caged Luciferase Inhibitor-Based Bioluminescence Switching Strategy Enables Efficient Detection of Serum APN Activity and the Identification of Its Roles in Metastasis of Non-Small Cell Lung Cancer.

Bioluminogenic probes emerged as powerful tools for imaging and analysis of various bioanalyses, but traditional approaches would be limited to the low sensitivity during determine the low activity of protease in clinical specimens. Herein, we proposed a caged luciferase inhibitor-based bioluminescence-switching strategy (CLIBS) by using a cleavable luciferase inhibitor to modulate the activity of luciferase reporter to amplify the detective signals, which led to the enhancement of detection sensitivity, and enabled the determination of circulating Aminopeptidase N (APN) activity in thousands of times diluted serum. By applying the CLIBS to serum samples in non-small cell lung cancer (NSCLC) patients from two clinical cohorts, we revealed that, for the first time, higher circulating APN activities but not its concentration, were associated with more NSCLC metastasis or higher metastasis stages by subsequent clinical analysis, and can serve as an independent factor for forecasting NSCLC patients' risk of metastasis.

The BAP31/miR-181a-5p/RECK axis promotes angiogenesis in colorectal cancer via fibroblast activation.

Background: B-cell receptor-associated protein 31 (BAP31) has been recognized as a tumor-associated protein and has largely been shown to promote metastasis in a variety of cancers. Cancer metastasis arises through multistep pathways, and the induction of angiogenesis is shown to be a rate-limiting step in the process of tumor metastasis. Methods and results: This study explored the effect of BAP31 on colorectal cancer (CRC) angiogenesis by regulating the tumor microenvironment. First, exosomes from BAP31-regulated CRCs affected the transition of normal fibroblasts to proangiogenic cancer-associated fibroblasts (CAFs) in vivo and in vitro. Next, microRNA sequencing was performed to analyze the microRNA expression profile of exosomes secreted from BAP31- overexpressing CRCs. The results indicated that the expression of BAP31 in CRCs significantly altered the levels of exosomal microRNAs, such as miR-181a- 5p. Meanwhile, an in vitro tube formation assay showed that fibroblasts with high levels of miR-181a-5p significantly promoted endothelial cell angiogenesis. Critically, we first identified that miR-181a-5p directly targeted the 3'-untranslated region (3'UTR) of reversion-inducing cysteine-rich protein with kazal motifs (RECK) using the dual-luciferase activity assay, which drove fibroblast transformation into proangiogenic CAFs by upregulating matrix metalloproteinase-9 (MMP-9) and phosphorylation of mothers against decapentaplegic homolog 2/Mothers against decapentaplegic homolog 3 (Smad2/3). Conclusion: Exosomes from BAP31-overexpressing/BAP31-knockdown CRCs are found to manipulate the transition of fibroblasts into proangiogenic CAFs by the miR-181a-5p/RECK axis.

B(C6F5)3-Catalyzed [4 + 2] Cyclization Strategy: Synthesis and Photophysical Properties of 5H-Naphtho[2,3-c]carbazole-8,13-dione Derivatives.

In this paper, a series of novel carbazolequinones were efficiently obtained by a B(C6F5)3-catalyzed [4 + 2] cyclization reaction. This protocol not only had a simple operation, broad substrate range, and high atomic economy, but also had a low catalyst loading and avoided using metal catalysts. In addition, we constructed diverse new carbazole-fused compounds under different reduction conditions. The results of photophysical characterization showed that the structure of carbazole-fused derivatives had a significant impact on the fluorescence properties.

Palbociclib enhances the effect of doxorubicin-induced apoptosis in activated B-cell-like diffuse large B-cell lymphoma cells.

Diffuse large B-cell lymphoma (DLBCL) is the most common non-Hodgkin lymphoma around the world. While R-CHOP has significantly improved patient outcomes, a subset of patients still has poor outcome. Here, the oncogenic roles of cyclin dependent kinase 4/6 (CDK4/6)-Cyclin D (CCND) signaling axis in DLBCL and its potential mechanism were investigated to explore the possibility of targeting CDK4/6-CCND signaling axis for DLBCL therapy. The transcription levels, functional enrichment analysis, mutation analysis, and prognostic values were performed via the Oncomine, GEPIA, UALCAN, cBioPortal, and Metascape and GenomicScape databases. Expression of CDK4/6-CCND signaling axis in DLBCL patients and DLBCL cell lines was evaluated by qRT-PCR. Additionally, the impact of CDK4/6-CCND signaling axis on cell viability and apoptosis in DLBCL cell lines were evaluated in vitro . The transcription levels of CDK4/6-CCND signaling were increased in DLBCL patients. Meanwhile, in Gene Expression Omnibus dataset, the expression of CDK4 and CCND2 was higher in ABC-DLBCL, whereas the expression of CCND1 and CCND3 was higher in GCB-DLBCL. Moreover, according to the results of qRT-PCR, the expression of CDK4/6-CCND signaling axis in ABC-DLBCL cell line is higher than that in GCB-DLBCL cell lines. Prognostic analysis indicated that upregulation of CDK4, CCND2, and CCND3 was significantly associated with poor survival. Cell function experiments showed that palbociclib could enhance the apoptosis-promoting and cell viability-inhibiting effects of doxorubicin on ABC-DLBCL (SU-DHL-2) cells. Doxorubicin accumulation experiment showed that palbociclib promoted doxorubicin accumulation in ABC-DLBCL cells. Additionally, Western blot analysis demonstrated that palbociclib prevented antiapoptotic protein BCL2 expression in ABC-DLBCL cell line. Our study provides novel insights into targeted therapies for ABC-DLBCL patients.

Gut-derived fungemia due to Kodamaea ohmeri combined with invasive pulmonary aspergillosis: a case report.

BACKGROUND: Kodamaea ohmeri is a rare pathogen with high mortality and is found among blood samples in a considerable proportion; however, gastrointestinal infection of K. ohmeri is extremely rare. Invasive pulmonary aspergillosis is also an uncommon fungal; these two fungal infections reported concomitantly are unprecedented. CASE PRESENTATION: We described a case of a 37-year-old male who got infected with K. ohmeri and invasive pulmonary aspergillosis. We used the mass spectrometry and histopathology to identify these two fungal infections separately. For the treatment of K. ohmeri, we chose caspofungin. As for invasive pulmonary aspergillosis, we used voriconazole, amphotericin B, and then surgery. The patient was treated successfully through the collaboration of multiple disciplines. CONCLUSIONS: We speculate that the destruction of the intestinal mucosa barrier can make the intestine one of the ways for certain fungi to infect the human body.

B(C6F5)3-catalyzed oxidation of α-diazoesters using DMF and molecular oxygen as oxygen sources.

A metal-free catalytic oxidation of α-diazoesters via a green environmental-friendly route was developed. The α-diazoesters were converted to α-ketoesters using DMF and molecular oxygen as oxygen sources and B(C6F5)3 as the catalyst, without any additives. This protocol has a broad adaptability of substrates and good compatibility with a range of functional groups, and it offers new insight into reactions catalyzed by B(C6F5)3.

Elevated circulating myeloid-derived suppressor cells associated with poor prognosis in B-cell non-Hodgkin's lymphoma patients.

INTRODUCTION: Myeloid-derived suppressor cells (MDSCs) are a heterogeneous cell population with the ability to suppress immune responses. MDSCs usually cluster in cancer, inflammation, and autoimmune diseases. Although there have been some studies on MDSCs in non-Hodgkin lymphoma (NHL), the correlation between the peripheral levels of MDSCs in patients with various subtypes of B cell NHL and clinical features and prognosis remains inconclusive. This study aimed at the issue. METHODS: 101 patients with B cell NHL and 15 age-matched healthy controls were included in this study. Flow cytometric detection of monocytic-MDSCs (M-MDSCs) and granulocytic-MDSCs (G-MDSCs) was done. RESULTS: In this study, we found that counts of circulating M-MDSCs and G-MDSCs were significantly increased in different clinical statuses of B-NHL patients compared to healthy controls. Similarly, a significant increase in the levels of M-MDSCs and G-MDSCs was found among the diverse types of B-NHL compared with healthy donors. Stratification studies indicated MDSCs expansion was closely associated with disease progression (tumor stage, LDH levels and B syndromes). Moreover, the overall survival time of patients with G-MDSCs (%) ≥ 98.70% was shorter than patients with G-MDSCs (%) < 98.70% in newly diagnosed B-NHL subgroup, meanwhile, there was a significant difference in survival of patients with M-MDSCs (%) ≥ 7.19% compared to patients with M-MDSCs (%) < 7.19% in relapsed B-NHL subgroup. CONCLUSION: Our results suggested that M-MDSCs and G-MDSCs may be a potential and efficient index to evaluate the prognosis of B-NHL patients.

Frameshifting at collided ribosomes is modulated by elongation factor eEF3 and by integrated stress response regulators Gcn1 and Gcn20.

Ribosome stalls can result in ribosome collisions that elicit quality control responses, one function of which is to prevent ribosome frameshifting, an activity that entails the interaction of the conserved yeast protein Mbf1 with uS3 on colliding ribosomes. However, the full spectrum of factors that mediate frameshifting during ribosome collisions is unknown. To delineate such factors in the yeast Saccharomyces cerevisiae, we used genetic selections for mutants that affect frameshifting from a known ribosome stall site, CGA codon repeats. We show that the general translation elongation factor eEF3 and the integrated stress response (ISR) pathway components Gcn1 and Gcn20 modulate frameshifting in opposing manners. We found a mutant form of eEF3 that specifically suppressed frameshifting, but not translation inhibition by CGA codons. Thus, we infer that frameshifting at collided ribosomes requires eEF3, which facilitates tRNA-mRNA translocation and E-site tRNA release in yeast and other single cell organisms. In contrast, we found that removal of either Gcn1 or Gcn20, which bind collided ribosomes with Mbf1, increased frameshifting. Thus, we conclude that frameshifting is suppressed by Gcn1 and Gcn20, although these effects are not mediated primarily through activation of the ISR. Furthermore, we examined the relationship between eEF3-mediated frameshifting and other quality control mechanisms, finding that Mbf1 requires either Hel2 or Gcn1 to suppress frameshifting with wild-type eEF3. Thus, these results provide evidence of a direct link between translation elongation and frameshifting at collided ribosomes, as well as evidence that frameshifting is constrained by quality control mechanisms that act on collided ribosomes.