A ZNRF3-dependent Wnt/ß-catenin signaling gradient is required for adrenal homeostasis.

Spatiotemporal control of Wnt signaling is essential for the development and homeostasis of many tissues. The transmembrane E3 ubiquitin ligases ZNRF3 (zinc and ring finger 3) and RNF43 (ring finger protein 43) antagonize Wnt signaling by promoting degradation of frizzled receptors. ZNRF3 and RNF43 are frequently inactivated in human cancer, but the molecular and therapeutic implications remain unclear. Here, we demonstrate that adrenocortical-specific loss of ZNRF3, but not RNF43, results in adrenal hyperplasia that depends on Porcupine-mediated Wnt ligand secretion. Furthermore, we discovered a Wnt/ß-catenin signaling gradient in the adrenal cortex that is disrupted upon loss of ZNRF3. Unlike ß-catenin gain-of-function models, which induce high Wnt/ß-catenin activation and expansion of the peripheral cortex, ZNRF3 loss triggers activation of moderate-level Wnt/ß-catenin signaling that drives proliferative expansion of only the histologically and functionally distinct inner cortex. Genetically reducing ß-catenin dosage significantly reverses the ZNRF3-deficient phenotype. Thus, homeostatic maintenance of the adrenal cortex is dependent on varying levels of Wnt/ß-catenin activation, which is regulated by ZNRF3.

To let go or not to let go: how ParA can impact the release of the chromosomal anchoring in Caulobacter crescentus.

Chromosomal maintenance is vital for the survival of bacteria. In Caulobacter crescentus, chromosome replication initiates at ori and segregation is delayed until the nearby centromere-like region parS is replicated. Our understanding of how this sequence of events is regulated remains limited. The segregation of parS has been shown to involve multiple steps including polar release from anchoring protein PopZ, slow movement and fast ParA-dependent movement to the opposite cell pole. In this study, we demonstrate that ParA's competing attractions from PopZ and from DNA are critical for segregation of parS. Interfering with this balance of attractions-by expressing a variant ParA-R195E unable to bind DNA and thus favoring interactions exclusively between ParA-PopZ-results in cell death. Our data revealed that ParA-R195E's sole interactions with PopZ obstruct PopZ's ability to release the polar anchoring of parS, resulting in cells with multiple parS loci fixed at one cell pole. We show that the inability to separate and segregate multiple parS loci from the pole is specifically dependent on the interaction between ParA and PopZ. Collectively, our results reveal that the initial steps in chromosome segregation are highly regulated.

Letter of recommendation characteristics associated with interview offer to a vascular surgery residency program.

BACKGROUND: Letters of recommendation (LORs) are considered by program directors (PDs) to be an integral part of the residency application. With the conversion of USMLE Step 1 to a binary pass/fail outcome, LORs will likely have higher important in the application process moving forward. However, their utility in securing an interview for a particular applicant remains undetermined. This study aims to identify the applicant and LOR characteristics associated with an interview invitation. METHODS: Letter writer (n=977) characteristics were abstracted from applications (n=264) to an individual integrated vascular surgery residency program over 2 application cycles. A validated text analysis program, Linguistic Inquiry and Word Count, was used to characterize LOR content. Applicant, letter writer, and LOR characteristics associated with an interview invitation was determined using multivariable analysis. RESULTS: Letter writers were 70.9% vascular surgeons (VS), 23.7% PDs, and 45.4% professors. Applicants offered an interview were more likely to come from a top 50 medical school (35.2% vs 25.8%, p=0.013) and an institution with a home vascular program (45.5% vs 34.1%, p=0.006). Alpha Omega Alpha membership was significantly associated with interview offer (28.4%, p<0.001). A greater proportion of letters from VS was associated with an interview offer (p <0.001) compared with letter writers of other specialties. One or more PD letters was significantly associated with an interview offer (79.55% vs 20.45%, p=0.008), whereas number of letters from APDs was not significantly associated with interview offer. Letters written by away institution faculty were significantly associated with interview offer (75%, p<0.001), whereas nonclinical letters were not. Presence of one or more letters from a chair (57.95% vs 42.05%, p=0.015) or chief (67.05% vs 32.95%, p=0.028) was significantly associated with interview offer. Letters for applicants offered an interview had more references to research and teaching, which were more common in letters written by VS. Letters written by PDs were more likely to use assertive, advertising language in favor of applicants. There were no significant applicant, letter writer, or LOR characteristics associated with a top 20 rank. CONCLUSION: Successful applicants were more likely to have LORs written by VS, PDs, and those of higher academic rank with references to research and teaching.

ParA's Impact beyond Chromosome Segregation in Caulobacter crescentus.

Maintaining proper chromosome inheritance after the completion of each cell cycle is paramount for bacterial survival. Mechanistic details remain incomplete for how bacteria manage to retain complete chromosomes after each cell cycle. In this study, we examined the potential roles of the partitioning protein ParA on chromosomal maintenance that go beyond triggering the onset of chromosome segregation in Caulobacter crescentus. Our data revealed that increasing the levels of ParA result in cells with multiple origins of replication in a DnaA-ATP-dependent manner. This ori supernumerary is retained even when expressing variants of ParA that are deficient in promoting chromosome segregation. Our data suggest that in Caulobacter ParA's impact on replication initiation is likely indirect, possibly through the effect of other cell cycle events. Overall, our data provide new insights into the highly interconnected network that drives the forward progression of the bacterial cell cycle. IMPORTANCE The successful generation of a daughter cell containing a complete copy of the chromosome requires the exquisite coordination of major cell cycle events. Any mistake in this coordination can be lethal, making these processes ideal targets for novel antibiotics. In this study, we focused on the coordination between the onset of chromosome replication, and the partitioning protein ParA. We demonstrate that altering the cellular levels of ParA causes cells to accumulate multiple origins of replication in Caulobacter crescentus. Our work provides important insights into the complex regulation involved in the coordination of the bacterial cell cycle.

Single-Institution Learning Curve for Management of Mega-Fistulae Revision.

BACKGROUND: Mega-fistulae are generalized aneurysmal dilations of a high flow (1500-4000 mL/min) autogenous arteriovenous (AV) access which may result in hemorrhage and/or high-output cardiac failure. Current treatments include ligation, ligation with prosthetic jump graft, and imbrication; however, these may not be suitable for advanced disease, or may result in loss of functioning access, poor cosmesis, or recurrence. We describe our early experience with a technique of complete mega-fistula resection and replacement with an early use prosthetic graft that both maintains existing AV access and eliminates the need for long-term catheter (LTC) placement; including lessons learned. METHODS: A single-center, retrospective review of medical records was conducted from March 2018-February 2021. Outcomes were technical success, LTC use, time to cannulation, and complications. Mega-fistulae were completely resected from the proximal to distal aneurysmal segment, including all pseudoaneurysms, followed by tunneling a prosthetic graft (Propaten later converted to Acuseal; W.L. Gore Assoc.) with an end-to-end anastomosis to the remaining arterial and venous ends of the previous AV access. RESULTS: We had 100% immediate technical success (n=12). Pre-operative long-term catheters were placed in all eight Propaten patients; one was already placed in an Acuseal patient.  Average time to cannulation was six weeks with Propaten and 4.5 days with Acuseal. At 30 days, three Propaten patients developed complications including one instance of skin necrosis, one seroma, and one hematoma. Two Acuseal patients developed complications including one central venous occlusion (CVO) and one graft infection. Of the six patients with long-term follow-up, five continue to use their access, however, two required thrombectomies and central venous angioplasties. One patient required a new contralateral access due to CVO. CONCLUSIONS: Complete mega-fistula resection and replacement with Acuseal graft maintains existing AV access and may eliminate the need for long-term catheter placement. Our early experience with this technique is encouraging, but further follow-up is required to determine the durability of this approach.

A Novel Angiography Scoring System Predicts Improvement After Isolated Common Femoral Endarterectomy With Profundaplasty.

BACKGROUND: Numerous angiography-based peripheral arterial disease classification schemes have been developed to stratify severity of preoperative patient disease, but few studies have correlated angiography-based anatomic classification schemes to postoperative outcomes. This study examined whether a proposed pre-operative angiography scoring system was predictive of outcomes after isolated common femoral endarterectomy with profundaplasty (CFEP). METHODS: A retrospective review was conducted of patients treated with isolated CFEP for claudication and/or rest pain at a single institution from 2016-19. Pre-operative angiograms were assessed quantitatively by 4 blinded surgeons across 3 domains: profunda stenosis, profunda disease length, and outflow disease severity. Table I describes the proposed angiography scoring system. Internal consistency reliability of rater scores was calculated using Cronbach alpha. Outcomes included clinical improvement, further interventions, major amputations, mortality, and mean increase in ankle-brachial index (ABI) at 30 days, and 6 months. McNemar tests, between-group t-tests, Pearson correlations, and linear regression were used. RESULTS: Clinical Outcomes 88% of patients (n = 22) had clinical improvement at 30 days; the remaining 12% of patients (n = 3) required further interventions. One patient (4%) required major amputation between 30 days and 6 months for recurrence of rest pain that had initially resolved after isolated CFEP. There was 0% mortality during the study period. Mean ABI increased by 0.15 ± 0.21 at 30 days, and by 0.06 ± 0.21 at 6 months. Angiography Scoring System Profunda stenosis score was associated with clinical improvement at 6 months (P = 0.04). A profunda stenosis score of ≥2.6 was strongly associated with 6-month clinical improvement (64% of those ≥ 2.6 improved, versus 15% of those <2.6, P = 0.15). Profunda stenosis score was associated with ABI improvement at 30 days (r = 0.73, P = 0.01) and 6 months (r = 0.82, P = 0.007). Profunda disease length score was associated with clinical improvement at 30 days (P = 0.002). 100% of patients with a profunda disease length score of ≥1.5 clinically improved at 30 days, versus 67% of those with <1.5 (P = 0.04). Angiography scores were not found to be associated with further intervention, major amputation, or mortality. Cronbach alpha for profunda stenosis, profunda disease length, and outflow severity scores were 0.90, 0.90, and 0.79, respectively, indicating strong internal consistency. CONCLUSIONS: This institutional angiography scoring system successfully predicts clinical improvement following CFEP.  Higher profunda stenosis and profunda disease length scores were most predictive of operative success within 6 months. Future validation studies will investigate these outcomes in a larger population, and over a longer period.

Steroidogenic differentiation and PKA signaling are programmed by histone methyltransferase EZH2 in the adrenal cortex.

Adrenal cortex steroids are essential for body homeostasis, and adrenal insufficiency is a life-threatening condition. Adrenal endocrine activity is maintained through recruitment of subcapsular progenitor cells that follow a unidirectional differentiation path from zona glomerulosa to zona fasciculata (zF). Here, we show that this unidirectionality is ensured by the histone methyltransferase EZH2. Indeed, we demonstrate that EZH2 maintains adrenal steroidogenic cell differentiation by preventing expression of GATA4 and WT1 that cause abnormal dedifferentiation to a progenitor-like state in Ezh2 KO adrenals. EZH2 further ensures normal cortical differentiation by programming cells for optimal response to adrenocorticotrophic hormone (ACTH)/PKA signaling. This is achieved by repression of phosphodiesterases PDE1B, 3A, and 7A and of PRKAR1B. Consequently, EZH2 ablation results in blunted zF differentiation and primary glucocorticoid insufficiency. These data demonstrate an all-encompassing role for EZH2 in programming steroidogenic cells for optimal response to differentiation signals and in maintaining their differentiated state.

Inhibition of fibronectin polymerization alleviates kidney injury due to ischemia-reperfusion.

Fibrosis is a common feature of chronic kidney disease; however, no clinical therapies effectively target the progression of fibrosis. Inhibition of fibronectin polymerization with the small peptide pUR4 attenuates fibrosis in the liver and heart. Here, we show that pUR4 decreases renal fibrosis and tissue remodeling using a clinically relevant model of kidney injury, unilateral ischemia-reperfusion. This work highlights the benefits of inhibiting matrix polymerization, alone or in conjunction with cell-based therapies, as a novel approach to diminish the maladaptive responses to ischemic kidney injury that lead to chronic renal failure.

EZH2 cooperates with E2F1 to stimulate expression of genes involved in adrenocortical carcinoma aggressiveness.

BACKGROUND: EZH2 is overexpressed and associated with poor prognosis in adrenocortical carcinoma (ACC) and its inhibition reduces growth and aggressiveness of ACC cells in culture. Although EZH2 was identified as the methyltransferase that deposits the repressive H3K27me3 histone mark, it can cooperate with transcription factors to stimulate gene transcription. METHODS: We used bioinformatics approaches on gene expression data from three cohorts of patients and a mouse model of EZH2 ablation, to identify targets and mode of action of EZH2 in ACC. This was followed by ChIP and functional assays to evaluate contribution of identified targets to ACC pathogenesis. RESULTS: We show that EZH2 mostly works as a transcriptional inducer in ACC, through cooperation with the transcription factor E2F1 and identify three positive targets involved in cell cycle regulation and mitosis i.e., RRM2, PTTG1 and ASE1/PRC1. Overexpression of these genes is associated with poor prognosis, suggesting a potential role in acquisition of aggressive ACC features. Pharmacological and siRNA-mediated inhibition of RRM2 blocks cell proliferation, induces apoptosis and inhibits cell migration, suggesting that it may be an interesting target in ACC. CONCLUSIONS: Altogether, these data show an unexpected role of EZH2 and E2F1 in stimulating expression of genes associated with ACC aggressiveness.

Racial disparities in late-stage prostate cancer: a SEER analysis 2005-2015.

INTRODUCTION: To evaluate the impact of prostate cancer screening guidelines on different racial and ethnic populations. MATERIALS AND METHODS: Data was collected from the 2005-2015 Surveillance, Epidemiology, and End Results (SEER) program. Incidence of prostate cancer diagnosis was categorized and analyzed by stage, race/ethnicity, and age group. Appropriate univariate and multivariable statistical analysis was performed. RESULTS: The odds of being diagnosed with regional-stage prostate cancer in 2013-2015 were 1.3 times higher for black men, 1.3 times higher for Asian American/Pacific Islander (AAPI) men, and 1.2 times higher for white men when compared to 2005-2008. The odds of being diagnosed with distant-stage prostate cancer in 2013-2015 were 1.6 times higher for black men, 1.8 times higher for AAPI men, and 2.1 times higher for white men when compared to 2005-2008. In 2005-2008, 2009-2012, and 2013-2015 respectively, the odds of being diagnosed with distant-stage prostate cancer were 1.8 times higher, 1.7 times higher, and 1.4 times higher for black men compared to white men, and 1.5 times higher, 1.5 times higher, and 1.4 times higher for AAPI men compared to white men (all respective p < .001). CONCLUSIONS: The proportion of late-stage prostate cancer has increased significantly in all US males regardless of race and/or ethnicity. From 2013-2015, all men had a higher chance of being diagnosed with regional or distant stage disease compared to years prior. Newly-diagnosed regional-stage disease increased the most over time in AAPI and black men, while distant prostate cancer increased the most over time in white men.

EZH2 is overexpressed in adrenocortical carcinoma and is associated with disease progression.

Adrenal Cortex Carcinoma (ACC) is an aggressive tumour with poor prognosis. Common alterations in patients include constitutive WNT/ß-catenin signalling and overexpression of the growth factor IGF2. However, the combination of both alterations in transgenic mice is not sufficient to trigger malignant tumour progression, suggesting that other alterations are required to allow development of carcinomas. Here, we have conducted a study of publicly available gene expression data from three cohorts of ACC patients to identify relevant alterations. Our data show that the histone methyltransferase EZH2 is overexpressed in ACC in the three cohorts. This overexpression is the result of deregulated P53/RB/E2F pathway activity and is associated with increased proliferation and poorer prognosis in patients. Inhibition of EZH2 by RNA interference or pharmacological treatment with DZNep inhibits cellular growth, wound healing and clonogenic growth and induces apoptosis of H295R cells in culture. Further growth inhibition is obtained when DZNep is combined with mitotane, the gold-standard treatment for ACC. Altogether, these observations suggest that overexpression of EZH2 is associated with aggressive progression and may constitute an interesting therapeutic target in the context of ACC.

ARMC5 mutations in macronodular adrenal hyperplasia with Cushing's syndrome.

BACKGROUND: Corticotropin-independent macronodular adrenal hyperplasia may be an incidental finding or it may be identified during evaluation for Cushing's syndrome. Reports of familial cases and the involvement of both adrenal glands suggest a genetic origin of this condition. METHODS: We genotyped blood and tumor DNA obtained from 33 patients with corticotropin-independent macronodular adrenal hyperplasia (12 men and 21 women who were 30 to 73 years of age), using single-nucleotide polymorphism arrays, microsatellite markers, and whole-genome and Sanger sequencing. The effects of armadillo repeat containing 5 (ARMC5) inactivation and overexpression were tested in cell-culture models. RESULTS: The most frequent somatic chromosome alteration was loss of heterozygosity at 16p (in 8 of 33 patients for whom data were available [24%]). The most frequent mutation identified by means of whole-genome sequencing was in ARMC5, located at 16p11.2. ARMC5 mutations were detected in tumors obtained from 18 of 33 patients (55%). In all cases, both alleles of ARMC5 carried mutations: one germline and the other somatic. In 4 patients with a germline ARMC5 mutation, different nodules from the affected adrenals harbored different secondary ARMC5 alterations. Transcriptome-based classification of corticotropin-independent macronodular adrenal hyperplasia indicated that ARMC5 mutations influenced gene expression, since all cases with mutations clustered together. ARMC5 inactivation decreased steroidogenesis in vitro, and its overexpression altered cell survival. CONCLUSIONS: Some cases of corticotropin-independent macronodular adrenal hyperplasia appear to be genetic, most often with inactivating mutations of ARMC5, a putative tumor-suppressor gene. Genetic testing for this condition, which often has a long and insidious prediagnostic course, might result in earlier identification and better management. (Funded by Agence Nationale de la Recherche and others.).

Boron Trifluoride Gas Adsorption in Metal-Organic Frameworks.

Coordinatively unsaturated metal-organic frameworks (MOFs) were studied for boron trifluoride (BF3) sorption. MOF-74-Mg, MOF-74-Mn, and MOF-74-Co show high initial uptake (below 6.7 × 10-3 bar) with negligible deliverable capacity. The BF3 isotherm of MOF-74-Cu exhibits gradual uptake up to 0.9 bar and has a deliverable gravimetric capacity that is more than 100% higher than activated carbon. Two other Cu2+ MOFs, MOF-505 and HKUST-1, have slightly lower deliverable capacities compared to MOF-74-Cu.

Hygiene strategies to prevent methicillin-resistant Staphylococcus aureus skin and soft tissue infections: a cluster-randomized controlled trial among high-risk military trainees.

BACKGROUND: Effective measures are needed to prevent methicillin-resistant Staphylococcus aureus (MRSA) skin and soft tissue infections (SSTIs) in high-risk community settings. The study objective was to evaluate the effect of personal hygiene-based strategies on rates of overall SSTI and MRSA SSTI. METHODS: We conducted a prospective, field-based, cluster-randomized trial in US Army Infantry trainees from May 2010 through January 2012. There were 3 study groups with incrementally increased education and hygiene-based interventions: standard (S), enhanced standard (ES), and chlorhexidine (CHG). The primary endpoints were incidence of overall SSTI and MRSA SSTI. RESULTS: The study included 30 209 trainees constituting 540 platoons (168 S, 192 ES, and 180 CHG). A total of 1203 (4%) participants developed SSTI, 316 (26%) due to MRSA. The overall SSTI rate was 4.15 (95% confidence interval [CI], 3.77-4.58) per 100 person-cycles. SSTI rates by study group were 3.48 (95% CI, 2.87-4.22) for S, 4.18 (95% CI, 3.56-4.90) for ES, and 4.71 (95% CI, 4.03-5.50) for CHG. The MRSA SSTI rate per 100 person-cycles for all groups was 1.10 (95% CI, .91-1.32). MRSA SSTI rates by study group were 1.0 (95% CI, .70-1.42) for S, 1.29 (95% CI, .98-1.71) for ES, and 0.97 (95% CI, .70-1.36) for CHG. CONCLUSIONS: Personal hygiene and education measures, including once-weekly use of chlorhexidine body wash, did not prevent overall SSTI or MRSA SSTI in a high-risk population of military trainees. CLINICAL TRIALS REGISTRATION: NCT01105767.

Leveraging Policy Solutions for Diabetes Disparities: Suggestions for Improving the National Clinical Care Commission Report's Recommendations for Hispanic/Latino Populations.

In the U.S., Hispanic/Latino populations face increased disparities in both the prevalence and management of type 2 diabetes mellitus (T2DM). This article critically examines the multifaceted nature of T2DM disparities among Hispanic/Latino populations in the U.S. and identifies key factors contributing to T2DM prevalence within these communities, including socioeconomic status, cultural influences, and healthcare access. Utilizing a modified expert consensus procedure, we evaluate the ways in which the National Clinical Care Commission (NCCC) recommendations apply to the Hispanic/Latino community as well as propose recommendations for improved efficacy. Through a comprehensive analysis of government-community health initiatives, food security, environmental exposures, and housing inequalities, we emphasize the need for targeted interventions and health policies to effectively address and dismantle these disparities. Overall, while the National Clinical Care Commission's recommendations provide a valuable framework for the implementation of policies pertaining to diabetes management and prevention in the general population, our analysis suggests that recommendations may be strengthened by considering the unique cultural, social, and economic needs of the Hispanic/Latino population moving forward.

Frequency of Treatment Failure of UTIs in Children With Congenital Urinary Tract Anomalies.

OBJECTIVES: Children with certain congenital anomalies of the kidney and urinary tract and neurogenic bladder (CAKUT/NGB) are at higher risk of treatment failure for urinary tract infections (UTIs) than children with normal genitourinary anatomy, but the literature describing treatment and outcomes is limited. The objectives of this study were to describe the rate of treatment failure in children with CAKUT/NGB and compare duration of antibiotics between those with and without treatment failure. METHODS: Multicenter retrospective cohort of children 0 to 17 years old with CAKUT/NGB who presented to the emergency department with fever or hypothermia and were diagnosed with UTI between 2017 and 2018. The outcome of interest was treatment failure, defined as subsequent emergency department visit or hospitalization for UTI because of the same pathogen within 30 days of the index encounter. Descriptive statistics and univariates analyses were used to compare covariates between groups. RESULTS: Of the 2014 patient encounters identified, 482 were included. Twenty-nine (6.0%) of the 482 included encounters had treatment failure. There was no difference in the mean duration of intravenous antibiotics (3.4 ± 2.5 days, 3.5 ± 2.8 days, P = .87) or total antibiotics between children with and without treatment failure (10.2 ± 3.8 days, 10.8 ± 4.0 days, P = .39) Of note, there was a higher rate of bacteremia in children with treatment failure (P = .04). CONCLUSIONS: In children with CAKUT/NGB and UTI, 6.0% of encounters had treatment failure. Duration of antibiotics was not associated with treatment failure. Larger studies are needed to assess whether bacteremia modifies the risk of treatment failure.

Complete chloroplast genome of the marine red alga Rhodochorton tenue (Rhodochortonaceae, Rhodophyta) from San Juan Island, Washington.

We present the complete chloroplast genome sequence of Rhodochorton tenue from San Juan Island, Washington. The chloroplast genome of R. tenue is 192,037 bp in length, contains 244 genes, and is similar in content to Acrochaetium secundatum. Rhodochorton tenue is genetically distinct from Rhodochorton purpureum from the North Atlantic Ocean.

Structural basis of specificity and cross-reactivity in T cell receptors specific for cytochrome c-I-E(k).

T cells specific for the cytochrome c Ag are widely used to investigate many aspects of TCR specificity and interactions with peptide-MHC, but structural information has long been elusive. In this study, we present structures for the well-studied 2B4 TCR, as well as a naturally occurring variant of the 5c.c7 TCR, 226, which is cross-reactive with more than half of possible substitutions at all three TCR-sensitive residues on the peptide Ag. These structures alone and in complex with peptide-MHC ligands allow us to reassess many prior mutagenesis results. In addition, the structure of 226 bound to one peptide variant, p5E, shows major changes in the CDR3 contacts compared with wild-type, yet the TCR V-region contacts with MHC are conserved. These and other data illustrate the ability of TCRs to accommodate large variations in CDR3 structure and peptide contacts within the constraints of highly conserved TCR-MHC interactions.

To let go or not to let go: how ParA can impact the release of the chromosomal anchoring in Caulobacter crescentus.

Chromosomal maintenance is vital for the survival of bacteria. In Caulobacter crescentus, chromosome replication initiates at ori and segregation is delayed until the nearby centromere-like region parS is replicated. Our understanding of how this sequence of events is regulated remains limited. The segregation of parS has been shown to involve multiple steps including polar release from anchoring protein PopZ, slow movement, and fast ParA-dependent movement to opposite cell pole. In this study, we demonstrate that ParA's competing attractions from PopZ and from DNA are critical for segregation of parS. Interfering with this balance of attractions - by expressing a variant ParA-R195E unable to bind DNA and thus favoring interactions exclusively between ParA-PopZ - results in cell death. Our data revealed that ParA-R195E's sole interactions with PopZ obstruct PopZ's ability to release the polar anchoring of parS resulting in cells with multiple parS loci fixed at one cell pole. We show that the inability to separate and segregate multiple parS loci from the pole is specifically dependent on the interaction between ParA and PopZ. Interfering with interactions between PopZ and the partitioning protein ParB, which is the interaction that anchors parS at the cell pole, does not rescue the ability of cells to separate the fixed parS loci when expressing parA-R195E. Thus, ParA and PopZ appear to have a distinct conversation from ParB yet can impact the release of ParB-parS from the anchoring at the cell pole. Collectively, our results reveal that the initial steps in chromosome segregation are highly regulated.

Identification of gingerenone A as a novel senolytic compound.

Senescent cells accumulate with aging and have been shown to contribute to age-associated diseases and organ dysfunction. Eliminating senescent cells with senolytic drugs has been shown to improve age phenotypes in mouse models and there is some initial evidence that it may improve the health of persons with chronic diseases. In this study, we employed WI-38 human fibroblasts rendered senescent by exposure to ionizing radiation (IR) to screen several plant extracts for their potential senolytic and/or senomorphic activity. Of these, ginger extract (Zingiber officinale Rosc.) selectively caused the death of senescent cells without affecting proliferating cells. Among the major individual components of ginger extract, gingerenone A and 6-shogaol showed promising senolytic properties, with gingerenone A selectively eliminating senescent cells. Similar to the senolytic cocktail dasatinib and quercetin (D+Q), gingerenone A and 6-shogaol elicited an apoptotic program. Additionally, both D+Q and gingerenone A had a pronounced effect on suppressing the senescence-associated secretory phenotype (SASP). Gingerenone A selectively promotes the death of senescent cells with no effect on non-senescent cells and these characteristics strongly support the idea that this natural compound may have therapeutic benefit in diseases characterized by senescent cell accumulation.