Influence of Wavy Arteries and Veins on Hemodynamic Characteristics: A Numerical Study.

The present work is focused on the study of hemodynamic characteristics for tortuous arteries/veins. Tortuosity in arteries/veins is defined by introducing waviness in the wall of the tube. Analysis is further extended for bifurcated veins with and without wavy walls. Waviness is defined by two geometric parameters; pitch and depth of the wave. Four different combinations of pitch and depth are studied and compared with a plain straight wall. The present study is carried out numerically by using a computational fluid dynamics tool. Hemodynamics for a steady flow of blood is investigated through pressure, velocity, and wall shear stress distribution. Waviness in the wall of arteries/veins creates a recirculation zone at the crest and trough of the wall. Occurrence of the recirculation zone leads to reduction in velocity which in turn reduces wall shear stress. Variation in the magnitude of the velocity and corresponding wall shear stress at the crest and trough of the wavy wall depends on the pitch and depth of the artery/veins (tube).

Segmentation-Based Fusion of CT and MR Images.

In this paper, a segmentation-based image fusion method is proposed for the fusion of MR and CT images to obtain a high contrast fused image that contains complementary information from both input images. The proposed method uses the fuzzy C-mean method to extract information about the skull from the CT image. This skull information is used to extract soft tissue information from the MR image. Both the skull information and the soft tissue information are then fused using the fusion rule. The efficiency of the proposed method over other state-of-the-art fusion methods is analyzed and compared using qualitative and quantitative analysis methods. Qualitative analysis shows the improvement in the contrast between the bone and the soft tissue using the proposed method over other state-of-the-art methods without introducing any artifacts or distortions. Classical and gradient-based quantitative analysis also show significant improvement in the fused image obtained using the proposed method over the five state-of-the-art methods. The percentage improvement in the standard deviation, average gradient, entropy, spatial frequency, QABF, and LABF of the proposed method over the best value obtained by the five state-of-the-art methods is 27.11%, 12.06%, 23.64%, 11.30%, 5.59%, and 13.70% respectively.

Neuronal nicotinic acetylcholine receptor of the central amygdala modulates the ethanol-induced tolerance to anxiolysis and withdrawal-induced anxiety in male rats.

The nicotine acetylcholinergic receptor (nAchR) in the central nucleus of the amygdala (CeA) is known to modulate anxiety traits as well as ethanol-induced behavioral effects. Therefore, the present study investigated the role of CeA nAChR in the tolerance to ethanol anxiolysis and withdrawal-induced anxiety-related effects in rats on elevated plus maze (EPM). To develop ethanol dependence, rats were given free access to an ethanol-containing liquid diet for 10 days. To assess the development of tolerance, separate groups of rats were challenged with ethanol (2 g/kg, i.p.) on days 1, 3, 5, 7 and 10 during the period of ethanol exposure, followed by an EPM assessment. Moreover, expression of ethanol withdrawal was induced after switching ethanol-dependent rats to a liquid diet on day 11, and withdrawal-induced anxiety-like behavior was noted at different post-withdrawal time points using the EPM test. The ethanol-dependent rats were pretreated with intra-CeA (i.CeA) (bilateral) injections of nicotine (0.25 µg/rat) or mecamylamine (MEC) (5 ng/rat) before the challenge dose of ethanol on subthreshold tolerance on the 5th day or on peak tolerance day, that is, 7th or 10th, and before assessment of postwithdrawal anxiety on the 11th day on EPM. Bilateral i.CeA preadministration of nicotine before the challenge dose of ethanol on days 5, 7 and 10 exhibited enhanced tolerance, while injection of MEC, completely mitigated the tolerance to the ethanol-induced antianxiety effect. On the other hand, ethanol-withdrawn rats pretreated i.CeA with nicotine exacerbated while pretreatment with MEC, alleviated the ethanol withdrawal-induced anxiety on all time points. Thus, the present investigation indicates that stimulation of nAChR in CeA negatively modulates the ethanol-induced chronic behavioral effects on anxiety in rats. It is proposed that nAChR antagonists might be useful in the treatment of alcohol use disorder and ethanol withdrawal-related anxiety-like behavior.

A step closer towards achieving universal health coverage: the role of gender in enrolment in health insurance in India.

BACKGROUND: There is limited understanding of how universal health coverage (UHC) schemes such as publicly-funded health insurance (PFHI) benefit women as compared to men. Many of these schemes are gender-neutral in design but given the existing gender inequalities in many societies, their benefits may not be similar for women and men. We contribute to the evidence by conducting a gender analysis of the enrolment of individuals and households in India's national PFHI scheme, Rashtriya Swasthya Bima Yojana (RSBY). METHODS: We used data from a cross-sectional household survey on RSBY eligible families across eight Indian states and studied different outcome variables at both the individual and household levels to compare enrolment among women and men. We applied multivariate logistic regressions and controlled for several demographic and socio-economic characteristics. RESULTS: At the individual level, the analysis revealed no substantial differences in enrolment between men and women. Only in one state were women more likely to be enrolled in RSBY than men (AOR: 2.66, 95% CI: 1.32-5.38), and this pattern was linked to their status in the household. At the household level, analyses revealed that female-headed households had a higher likelihood to be enrolled (AOR: 1.36, 95% CI: 1.14-1.62), but not necessarily to have all household members enrolled. CONCLUSION: Findings are surprising in light of India's well-documented gender bias, permeating different aspects of society, and are most likely an indication of success in designing a policy that did not favour participation by men above women, by mandating spouse enrolment and securing enrolment of up to five family members. Higher enrolment rates among female-headed households are also an indication of women's preferences for investments in health, in the context of a conducive policy environment. Further analyses are needed to examine if once enrolled, women also make use of the scheme benefits to the same extent as men do. India is called upon to capitalise on the achievements of RSBY and apply them to newer schemes such as PM-JAY.

Central cholinergic transmission affects the compulsive-like behavior of mice in marble-burying test.

The presence of the cholinergic system in the brain areas implicated in the precipitation of obsessive-compulsive behavior (OCB) has been reported but the exact role of the central cholinergic system therein is still unexplored. Therefore, the current study assessed the effect of cholinergic analogs on central administration on the marble-burying behavior (MBB) of mice, a behavior correlated with OCB. The result reveals that the enhancement of central cholinergic transmission in mice achieved by intracerebroventricular (i.c.v.) injection of acetylcholine (0.01 µg) (Subeffective: 0.1 and 0.5 µg), cholinesterase inhibitor, neostigmine (0.1, 0.3, 0.5 µg/mouse) and neuronal nicotinic acetylcholine receptor agonist, nicotine (0.1, 2 µg/mouse) significantly attenuated the number of marbles buried by mice in MBB test without affecting basal locomotor activity. Similarly, central injection of mAChR antagonist, atropine (0.1, 0.5, 5 µg/mouse), nAChR antagonist, mecamylamine (0.1, 0.5, 3 µg/mouse) per se also reduced the MBB in mice, indicative of anti-OCB like effect of all the tested cholinergic mAChR or nAChR agonist and antagonist. Surprisingly, i.c.v. injection of acetylcholine (0.01 µg), and neostigmine (0.1 µg) failed to elicit an anti-OCB-like effect in mice pre-treated (i.c.v.) with atropine (0.1 µg), or mecamylamine (0.1 µg). Thus, the findings of the present investigationdelineate the role of central cholinergic transmission in the compulsive-like behavior of mice probably via mAChR or nAChR stimulation.

Post-translational modifications and their implications in cancer.

Post-translational modifications (PTMs) are crucial regulatory mechanisms that alter the properties of a protein by covalently attaching a modified chemical group to some of its amino acid residues. PTMs modulate essential physiological processes such as signal transduction, metabolism, protein localization, and turnover and have clinical relevance in cancer and age-related pathologies. Majority of proteins undergo post-translational modifications, irrespective of their occurrence in or after protein biosynthesis. Post-translational modifications link to amino acid termini or side chains, causing the protein backbone to get cleaved, spliced, or cyclized, to name a few. These chemical modifications expand the diversity of the proteome and regulate protein activity, structure, locations, functions, and protein-protein interactions (PPIs). This ability to modify the physical and chemical properties and functions of proteins render PTMs vital. To date, over 200 different protein modifications have been reported, owing to advanced detection technologies. Some of these modifications include phosphorylation, glycosylation, methylation, acetylation, and ubiquitination. Here, we discuss about the existing as well as some novel post-translational protein modifications, with their implications in aberrant states, which will help us better understand the modified sites in different proteins and the effect of PTMs on protein functions in core biological processes and progression in cancer.

Evolving Role and Clinical Evidence in the Global Practice of Balloon Pulmonary Angioplasty.

Balloon pulmonary angioplasty (BPA) was first described in 2001 and now has evolved into a class I indication for inoperable or residual chronic thromboembolic pulmonary hypertension. This review article aims to describe evidence from studies performed at various pulmonary hypertension (PH) centers across the globe, to better understand the role of BPA in chronic thromboembolic pulmonary disease with and without PH. Additionally, we hope to highlight innovations and the ever-changing safety and efficacy profile of BPA.

Diaryl ether derivative inhibits GPX4 expression levels to induce ferroptosis in thyroid cancer cells.

Papillary thyroid carcinoma contributes to about 80% of the total thyroid cancer cases. BRAFV600E is a frequently occurring mutation in PTCs. Although several BRAF inhibitors are available, many thyroid cancer patients acquire resistance to BRAF inhibitors. Therefore, new targets and drugs need to be identified as therapies. Ferroptosis is a recently discovered type of cell death, and inhibiting glutathione peroxidase 4 (GPX4) using small molecules was found to trigger ferroptosis. But it is unknown whether inhibiting GPX4 renders thyroid cancer cells susceptible to ferroptosis. To identify novel GPX4 inhibitors, we focused on our previously reported cohort of diaryl ether and dibenzoxepine molecules. In this study, we asked whether diaryl ether and dibenzoxepine derivatives trigger ferroptosis in thyroid cancer cells. To answer this question, we screened diaryl ether and dibenzoxepine derivatives in cell-based assays and performed mechanism of action studies. We found that a diaryl ether derivative, 16 decreased thyroid cell proliferation and triggered ferroptosis by inhibiting GPX4 expression levels. Molecular modeling and dynamics simulations showed that 16 binds to the active site of GPX4. Upon deciphering the mode of 16-induced ferroptosis, we found that 16 treatments decrease mitochondrial polarization and reduce mitochondrial respiration similar to a ferroptosis inducer, RSL3. We conclude that the diaryl ether derivative, 16 inhibits GPX4 expression levels to induce ferroptosis in thyroid cancer cells. Based on our observations, we suggest that 16 can be lead-optimized and developed as a ferroptosis-inducing agent to treat thyroid cancers.

Retinoic acid and evernyl-based menadione-triazole hybrid cooperate to induce differentiation of neuroblastoma cells.

Neuroblastoma arises when immature neural precursor cells do not mature into specialized cells. Although retinoic acid (RA), a pro-differentiation agent, improves the survival of low-grade neuroblastoma, resistance to retinoic acid is found in high-grade neuroblastoma patients. Histone deacetylases (HDAC) inhibitors induce differentiation and arrest the growth of cancer cells; however, HDAC inhibitors are FDA-approved mostly for liquid tumors. Therefore, combining histone deacetylase (HDAC) inhibitors and retinoic acid can be explored as a strategy to trigger the differentiation of neuroblastoma cells and to overcome resistance to retinoic acid. Based on this rationale, in this study, we linked evernyl group and menadione-triazole motifs to synthesize evernyl-based menadione-triazole hybrids and asked if the hybrids cooperate with retinoic acid to trigger the differentiation of neuroblastoma cells. To answer this question, we treated neuroblastoma cells using evernyl-based menadione-triazole hybrids (6a-6i) or RA or both and examined the differentiation of neuroblastoma cells. Among the hybrids, we found that compound 6b inhibits class-I HDAC activity, induces differentiation, and RA co-treatments increase 6b-induced differentiation of neuroblastoma cells. In addition, 6b reduces cell proliferation, induces expression of differentiation-specific microRNAs leading to N-Myc downregulation, and RA co-treatments enhance the 6b-induced effects. We observed that 6b and RA trigger a switch from glycolysis to oxidative phosphorylation, maintain mitochondrial polarization, and increase oxygen consumption rate. We conclude that in evernyl-based menadione-triazole hybrid, 6b cooperates with RA to induce differentiation of neuroblastoma cells. Based on our results, we suggest that combining RA and 6b can be pursued as therapy for neuroblastoma. Schematic representation of RA and 6b in inducing differentiation of neuroblastoma cells.

Periprocedural Complications With Balloon Pulmonary Angioplasty: Analysis of Global Studies.

BACKGROUND: Balloon pulmonary angioplasty (BPA) was introduced as a treatment modality for patients with inoperable, medically refractory chronic thromboembolic pulmonary hypertension decades ago; however, reports of high rates of pulmonary vascular injury have led to considerable refinement in procedural technique. OBJECTIVES: The authors sought to better understand the evolution of BPA procedure-related complications over time. METHODS: The authors conducted a systematic review of original articles published by pulmonary hypertension centers globally and performed a pooled cohort analysis of procedure-related outcomes with BPA. RESULTS: This systematic review identified 26 published articles from 18 countries worldwide from 2013 to 2022. A total of 1,714 patients underwent 7,561 total BPA procedures with an average follow up of 7.3 months. From the first period (2013-2017) to the second period (2018-2022), the cumulative incidence of hemoptysis/vascular injury decreased from 14.1% (474/3,351) to 7.7% (233/3,029) (P < 0.01); lung injury/reperfusion edema decreased from 11.3% (377/3,351) to 1.4% (57/3,943) (P < 0.01); invasive mechanical ventilation decreased from 0.7% (23/3,195) to 0.1% (4/3,062) (P < 0.01); and mortality decreased from 2.0% (13/636) to 0.8% (8/1,071) (P < 0.01). CONCLUSIONS: Procedure-related complications with BPA, including hemoptysis/vascular injury, lung injury/reperfusion edema, mechanical ventilation, and death, were less common in the second period (2018-2022), compared with first period (2013-2017), likely from refinement in patient and lesion selection and procedural technique over time.

A glaucoma-associated OPTN polymorphism, M98K sensitizes retinal cells to endoplasmic reticulum stress and tumour necrosis factor α.

Optineurin/OPTN polymorphism, M98K is associated with normal tension glaucoma in certain populations, and genetic evidence shows its interaction with tumour necrosis factor-alpha (TNFα) polymorphism in causing glaucoma. Endoplasmic reticulum (ER) stress is also associated with glaucoma. We hypothesized that M98K-OPTN may sensitize retinal ganglion cells to various types of stress. To test this hypothesis, stable clones of a retinal cell line, 661W, expressing either wild-type (WT)-OPTN or M98K-OPTN were generated and examined for their survival under various stress conditions. Compared with WT-OPTN expressing cells, M98K-OPTN expressing cells showed significantly lower cell survival and higher activation of caspase-3 and caspase-8 upon treatment with tunicamycin (an inducer of ER stress) or TNFα. Levels of ER stress sensors IRE1α, PERK and ATF6 were significantly higher in M98K-OPTN expressing cells. Tunicamycin treatment resulted in significantly higher induction of ER stress marker CHOP and several other ER stress response genes regulated by IRE1α-XBP1, PERK-ATF4 and ATF6 pathways, in M98K-OPTN expressing cells. Splicing of XBP1 and ATF6 activation was higher in tunicamycin-treated M98K-OPTN expressing cells. Increased levels of PERK and IRE1α proteins in M98K-OPTN expressing cells were dependent on autophagy. Overall, our results show that M98K-OPTN sensitizes retinal cells to TNFα and ER stress-induced cell death. We also show that M98K-OPTN alters ER stress response signalling, which possibly enhances the sensitivity of retinal cells to ER stress. Our results provide support to the hypothesis that M98K-OPTN may cooperate with other genetic or environmental factors to cause retinal ganglion cell death associated with glaucoma.

APC/C CDH1 ubiquitinates STAT3 in mitosis.

STAT3, an oncogene drives tumor growth and is associated with poor prognosis. However, small molecule-based STAT3 inhibitors were unsuccessful in clinics. Recently, STAT3 degraders that ubiquitinate STAT3 were found to elicit long-lasting anti-tumor responses. Thus, triggering STAT3 ubiquitination in cancers is a better strategy than STAT3 inhibition. However, not much is known about the identity of E3-ligases that ubiquitinate STAT3 in cancers. Therefore, to design better therapies to degrade STAT3, we sought to identify E3-ligases that ubiquitinate STAT3 in cancer cells. To answer this question, we determined the cell cycle-dependent ubiquitination of STAT3 in HEK293T cells and examined the link between STAT3 dephosphorylation and ubiquitination. We found that STAT3 is more strongly ubiquitinated in mitosis than in other phases of the cell cycle. We observed that APC/C CDH1 binds and ubiquitinates STAT3 in mitosis. Further, we also found that inhibiting phosphatases decreases STAT3 ubiquitination. We conclude that APC/C CDH1 ubiquitinates STAT3 in mitosis. We suggest that mitosis can be a potential therapeutic window for treating STAT3-activated cancers.

Everyday capabilities were a path to resilience during COVID-19: a case study of five countries.

COVID-19 demanded urgent responses by all countries, with wide variations in the scope and sustainability of those responses. Scholarship on resilience has increasingly emphasized relational considerations such as norms and power and how they influence health systems' responses to evolving challenges. In this study, we explored what influenced countries' national pandemic responses over time considering a country's capacity to test for COVID-19. To identify countries for inclusion, we used daily reports of COVID-19 cases and testing from 184 countries between 21st January 2020 and 31st December 2020. Countries reporting test data consistently and for at least 105 days were included, yielding a sample of 52 countries. We then sampled five countries representing different geographies, income levels and governance structures (Belgium, Ethiopia, India, Israel and Peru) and conducted semi-structured key informant interviews with stakeholders working in, or deeply familiar with, national responses. Across these five countries, we found that existing health systems capacities and political leadership determined how responses unfolded, while emergency plans or pandemic preparedness documents were not fit-for-purpose. While all five countries were successful at reducing COVID-19 infections at a specific moment in the pandemic, political economy factors complicated the ability to sustain responses, with all countries experiencing larger waves of the virus in 2021 or 2022. Our findings emphasize the continued importance of foundational public health and health systems capacities, bolstered by clear leadership and multisectoral coordination functions. Even in settings with high-level political leadership and a strong multisectoral response, informants wished that they-and their country's health system-were more prepared to address the pandemic and maintain an effective response over time. Our findings challenge emergency preparedness as the dominant frame in pandemic preparedness and call for a continued emphasis on health systems strengthening to respond to future health shocks and a pandemic moving to endemic status.

Prohibitin1 maintains mitochondrial quality in isoproterenol-induced cardiac hypertrophy in H9C2 cells.

BACKGROUND INFORMATION: Various types of stress initially induce a state of cardiac hypertrophy (CH) in the heart. But, persistent escalation of cardiac stress leads to progression from an adaptive physiological to a maladaptive pathological state. So, elucidating molecular mechanisms that can attenuate CH is imperative in developing cardiac therapies. Previously, we showed that Prohibitin1 (PHB1) has a protective role in CH-induced oxidative stress. Nevertheless, it is unclear how PHB1, a mitochondrial protein, has a protective role in CH. Therefore, we hypothesized that PHB1 maintains mitochondrial quality in CH. To test this hypothesis, we used Isoproterenol (ISO) to induce CH in H9C2 cells overexpressing PHB1 and elucidated mitochondrial quality control pathways. RESULTS: We found that overexpressing PHB1 attenuates ISO-induced CH and restores mitochondrial morphology in H9C2 cells. In addition, PHB1 blocks the pro-hypertrophic IGF1R/AKT pathway and restores the mitochondrial membrane polarization in ISO-treated cells. We observed that overexpressing PHB1 promotes mitochondrial biogenesis, improves mitochondrial respiratory capacity, and triggers mitophagy. CONCLUSION: We conclude that PHB1 maintains mitochondrial quality in ISO-induced CH in H9C2 cells. SIGNIFICANCE: Based on our results, we suggest that small molecules that induce PHB1 in cardiac cells may prove beneficial in developing cardiac therapies.

Awareness of India's national health insurance scheme (PM-JAY): a cross-sectional study across six states.

The literature suggests that a first barrier towards accessing benefits of health insurance in low- and middle-income countries is lack of awareness of one's benefits. Yet, across settings and emerging schemes, limited scientific evidence is available on levels of awareness and their determinants. To fill this gap, we assessed socio-demographic and economic determinants of beneficiaries' awareness of the Pradhan Mantri Jan Arogya Yojana (PM-JAY), the national health insurance scheme launched in India in 2018, and their awareness of own eligibility. We relied on cross-sectional household (HH) survey data collected in six Indian states between 2019 and 2020. Representative data of HHs eligible for PM-JAY from 11 618 respondents (an adult representative from each surveyed HH) were used. We used descriptive statistics and multivariable logistic regression models to explore the association between awareness of PM-JAY and of one's own eligibility and socio-economic and demographic characteristics. About 62% of respondents were aware of PM-JAY, and among the aware, 78% knew that they were eligible for the scheme. Regression analysis confirmed that older respondents with a higher educational level and salaried jobs were more likely to know about PM-JAY. Awareness was lower among respondents from Meghalaya and Tamil Nadu. Respondents from Other Backward Classes, of wealthier socio-economic status or from Meghalaya or Gujarat were more likely to be aware of their eligibility status. Respondents from Chhattisgarh were less likely to know about their eligibility. Our study confirms that while more than half of the eligible population was aware of PM-JAY, considerable efforts are needed to achieve universal awareness. Socio-economic gradients confirm that the more marginalized are still less aware. We recommend implementing tailored, state-specific information dissemination approaches focusing on knowledge of specific scheme features to empower beneficiaries to demand their entitled services.

COVID-19 vaccine equity and health equity conversations on Twitter.

This study used social network analysis and trending hashtags on Twitter to identify trends related to health and vaccine equity during the Omicron wave. The analysis was conducted using consumer-friendly platforms/tools such as the Healthcare Hashtag Project and NodeXL. The study found that during the Omicron wave, there was a higher volume of tweets related to the more specific hashtag #VaccineEquity, as compared to the more general topic of #HealthEquity. The study also identified the top influencers for these hashtags and how they changed over time. The study proposes a combination of existing tools and approaches, including ontological surveillance and social network analysis, to develop proactive strategies that respond to public opinion in a timely manner. Social network analysis tools could also be useful for healthcare organizations and providers in training their staff involved in social media management to develop better social media communication strategies.

Who Influences Cancer Conversations on Twitter?: A Comparative Surveillance of Cancer Communications.

In this study, we used social network analysis to compare the Twitter social networks of top five cancers in the United States (as ranked by the CDC) to determine the key influencers in cancer-related conversations. We find that organizations and groups geared toward patients that provide patient support, promote cancer awareness, cancer prevention and cancer management comprised up to 40% of influencers. Researchers (24%) and physicians (14%) were also found to be influential participants; the extent of influence varying by each cancer, being as high as 40% research influence for colorectal cancer. Notably, scientific organizations (JAMA, CDC_cancer, AACR) played a key role in conversations about colorectal cancer whereas patient-focused organizations played a greater influencing role in conversations about prostate cancer and skin cancer. This study shows that Twitter data can be a valuable source of cancer surveillance data, and has potential to influence policies, strategies, and research directions around each cancer.

Plk1 regulates mutant IDH1 enzyme activity and mutant IDH2 ubiquitination in mitosis.

Mutations in the metabolic enzymes, IDH1 and IDH2 are frequently found in glioma, chondrosarcoma, and acute myeloid leukemia. In our previous study, we showed that mutant IDH1 and IDH2 proteins levels are high in mitosis, and mutant IDH1 enzyme activity increases in mitosis. In another study, we observed that mutant IDH2 is ubiquitinated in mitosis in an APC/C-dependent manner. To orchestrate mitosis, kinases phosphorylate key proteins and regulate their functions. But it is unknown, whether mitotic kinases regulate mutant IDH1 and IDH2. As IDH1 and IDH2 have 66% sequence identity, thus we hypothesized that a common mitotic kinase(s) may regulate mutant IDH1 and IDH2 in mitosis. To test our hypothesis, we examined mutant IDH1 and IDH2 binding to mitotic kinases and determined their role in regulating mutant IDH1 and IDH2 in mitosis. Here, we observed that Cdk1/Cyclin B1 phosphorylated mutant IDH1 and IDH2 binds Plk1. Conserved Plk1 phosphobinding sites in IDH1 and IDH2 are important for Plk1 binding. We found that Plk1 regulates mutant IDH1 enzyme activity and blocking Plk1 decreases D-2HG, whereas, overexpressing Plk1 increases D-2HG levels. Furthermore, blocking Plk1 decreases mutant IDH2 ubiquitination, whereas, overexpressing Plk1 increases mutant IDH2 ubiquitination in mitosis. We conclude that Plk1 regulates mutant IDH1 enzyme activity and mutant IDH2 ubiquitination in mitosis. Based on our results, we suggest that Plk1 can be a therapeutic target in mutant IDH-linked tumours.

APC/C CDH1 ubiquitinates IDH2 contributing to ROS increase in mitosis.

NADPH is a cofactor used by reactive oxygen species (ROS) scavenging enzymes to block ROS produced in cells. Recently, it was shown that in cancer cells, ROS progressively increases in tune to cell cycle leading to a peak in mitosis. Loss of IDH2 is known to cause severe oxidative stress in cell and mouse models as ROS increases in mitochondria. Therefore, we hypothesized that IDH2, a major NADPH-producing enzyme in mitochondria is ubiquitinated for ROS to increase in mitosis. To test this hypothesis, in cancer cells we examined IDH2 ubiquitination in mitosis and measured the ROS produced. We found that IDH2 is ubiquitinated in mitosis and on inhibiting anaphase-promoting complex/Cyclosome (APC/C) IDH2 was stabilized. Further, we observed that overexpressing APC/C coactivator CDH1 decreased IDH2, whereas depleting CDH1 decreased IDH2 ubiquitination. To understand the link between IDH2 ubiquitination and ROS produced in mitosis, we show that overexpressing mitochondria-targeted-IDH1 decreased ROS by increasing NADPH in IDH2 ubiquitinated cells. We conclude that APC/C CDH1 ubiquitinates IDH2, a major NADPH-producing enzyme in mitochondria contributing to ROS increase in mitosis. Based on our results, we suggest that mitosis can be a therapeutic window in mutant IDH2-linked pathologies.