The alkylation response protein AidB is localized at the new poles and constriction sites in Brucella abortus

<p>Abstract</p> <p>Background</p> <p><it>Brucella abortus </it>is the etiological agent of a worldwide zoonosis called brucellosis. This alpha-proteobacterium is dividing asymmetrically, and PdhS, an essential histidine kinase, was reported to be an old pole marker.</p> <p>Results</p> <p>We were interested to identify functions that could be recruited to bacterial poles. The <it>Brucella </it>ORFeome, a collection of cloned predicted coding sequences, was placed in fusion with yellow fluorescent protein (YFP) coding sequence and screened for polar localizations in <it>B. abortus</it>. We report that AidB-YFP was systematically localized to the new poles and at constrictions sites in <it>B. abortus</it>, either in culture or inside infected HeLa cells or RAW264.7 macrophages. AidB is an acyl-CoA dehydrogenase (ACAD) homolog, similar to <it>E. coli </it>AidB, an enzyme putatively involved in destroying alkylating agents. Accordingly, a <it>B. abortus aidB </it>mutant is more sensitive than the wild-type strain to the lethality induced by methanesulphonic acid ethyl ester (EMS). The exposure to EMS led to a very low frequency of constriction events, suggesting that cell cycle is blocked during alkylation damage. The localization of AidB-YFP at the new poles and at constriction sites seems to be specific for this ACAD homolog since two other ACAD homologs fused to YFP did not show specific localization. The overexpression of <it>aidB</it>, but not the two other ACAD coding sequences, leads to multiple morphological defects.</p> <p>Conclusions</p> <p>Data reported here suggest that AidB is a marker of new poles and constriction sites, that could be considered as sites of preparation of new poles in the sibling cells originating from cell division. The possible role of AidB in the generation or the function of new poles needs further investigation.</p

G1-arrested newborn cells are the predominant infectious form of the pathogen Brucella abortus

Several intracellular pathogens, such as Brucella abortus, display a biphasic infection process starting with a non-proliferative stage of unclear nature. Here, we study the cell cycle of B. abortus at the single-cell level, in culture and during infection of HeLa cells and macrophages. The localization of segregation and replication loci of the two bacterial chromosomes indicates that, immediately after being engulfed by host-cell endocytic vacuoles, most bacterial cells are newborn. These bacterial cells do not initiate DNA replication for the next 4 to 6 h, indicating a G1 arrest. Moreover, growth is completely stopped during that time, reflecting a global cell cycle block. Growth and DNA replication resume later, although bacteria still reside within endosomal-like compartments. We hypothesize that the predominance of G1-arrested bacteria in the infectious population, and the bacterial cell cycle arrest following internalization, may constitute a widespread strategy among intracellular pathogens to colonize new proliferation niches

PdhS, an Old-Pole-Localized Histidine Kinase, Recruits the Fumarase FumC in Brucella abortus▿ †

The bacterial pathogen Brucella abortus was recently demonstrated to recruit the essential cytoplasmic histidine kinase PdhS to its old pole. Here, we report identification of the fumarase FumC as a specific partner for the N-terminal “sensing” domain of PdhS, using an ORFeome-based yeast two-hybrid screen. We observed that FumC and PdhS colocalize at the old pole of B. abortus, while the other fumarase FumA is not polarly localized. FumC is not required for PdhS localization, and polar FumC localization is not FumA dependent. FumC homologs are not polarly localized in Sinorhizobium meliloti and Caulobacter crescentus, suggesting that polar recruitment of FumC by PdhS is evolutionarily recent

Impact of the relative dose intensity on survival of patients with high‐risk myelodysplastic syndromes treated with Azacitidine

Abstract We performed a retrospective analysis of 93 myelodysplastic syndromes (MDS) patients with intermediate 2 or high‐risk IPSS score to study the impact of Azacitidine (AZA) relative dose intensity (RDI) <80% on the overall survival (OS). There were 51.6% of patients who had full dose and 48.4% had dose reduction or delayed with a RDI <80%. Nineteen patients (20.4%) had RDI <80% before getting objective response. Overall and progression‐free survivals (OS, PFS) probabilities for the whole population were 58% (95% CI: 48‐69) and 47% (95% CI: 38‐58) at 1 year; 35% (95% CI: 26‐47) and 31% (95% CI: 23‐43) at two years, respectively. When analyzing the outcomes according to the response to AZA, median OS was 32 months (range: 26‐55) for responders and 8 months (range: 7‐12) for nonresponders, with a respective 1‐year and 2‐year OS probabilities of 91% vs 28% and 66% vs 6%, respectively (P < 0.001). Interestingly, there was no impact of dose reduction on OS nor on PFS, however, when analyzing the timing of dose reduction as time‐dependent variable, we found that patients who had dose reduction before achieving the objective response, had significantly lower OS (P = 0.02) and PFS (P = 0.01) compared to patients who had dose reduction after achieving the objective response. In multivariate analysis, acute myeloid leukemia with 21%‐30% blasts in BM and poor and very poor karyotype significantly impacted OS, (HR = 2.09, 95% CI: 1.27‐3.44, P = 0.004, and HR = 2.73, 95% CI: 1.6‐4.6, P < 0.001 respectively), as well as PFS (HR = 1.84, 95% CI: 1.07‐3.17, P = 0.028, and HR = 3.03, 95% CI: 1.7‐5.39, P < 0.001, respectively)

Arabidopsis thaliana plant defensin AtPDF1.1 is involved in the plant response to biotic stress

*Previously, it was shown that the Arabidopsis thaliana plant defensins AtPDF1.1 (At1g75830) and AtPDF1.2a (At5g44420) exert in vitro antimicrobial properties and that their corresponding genes are expressed in seeds and induced in leaves upon pathogen attack, respectively. *In this study, the expression profile of both AtPDF1.1 and AtPDF1.2a is analysed in wild-type plants upon different stress-related treatments and the effect of modulation of their expression in transgenic plants is examined in both host and nonhost resistance. *AtPDF1.1, which was originally considered to be seed-specific, is demonstrated to be locally induced in leaves upon fungal attack and exhibits an expression profile distinct from that of AtPDF1.2a, a gene frequently used as marker for the ethylene/jasmonate-mediated signaling pathway. Transgenic plants with modulated AtPDF1.1 or AtPDF1.2a gene expression show no altered phenotype upon Botrytis cinerea inoculation. However, constitutive overexpression of AtPDF1.1 in A. thaliana leads to a reduction in symptoms caused by the nonhost Cercospora beticola causing non-spreading spots on A. thaliana leaves. *These results indicate that AtPDF1.1 and AtPDF1.2a clearly differ regarding their expression profile and functionality in planta. It emphasizes the additional level of complexity and fine-tuning within the highly redundant plant defensin genes in A. thaliana.status: publishe

Influence of growth hormone therapy on the occurrence of a second neoplasm in survivors of childhood cancer

International audienceContext: Growth hormone (GH) deficiency is a common late effect of cranial irradiation. However, concerns have been raised that GH treatment might lead to an increased risk of a second neoplasm (SN). Objective: To study the impact of GH treatment on the risk of SN in a French cohort of survivors of childhood cancer (CCS) treated before 1986. Design and setting: Cohort study and nested case–control study. Participants: Of the 2852 survivors, with a median follow-up of 26 years, 196 had received GH therapy (median delay from cancer diagnosis: 5.5 years). Main outcome measures: Occurrence of SN Results: In total, 374 survivors developed a SN, including 40 who had received GH therapy. In a multivariate analysis, GH treatment did not increase the risk of secondary non-meningioma brain tumors (RR: 0.6, 95% CI: 0.2–1.5, P = 0.3), secondary non-brain cancer (RR: 0.7, 95% CI: 0.4–1.2, P = 0.2), or meningioma (RR: 1.9, 95% CI: 0.9–4, P = 0.09). Nevertheless, we observed a slight non-significant increase in the risk of meningioma with GH duration: 1.6-fold (95% CI: 1.2–3.0) after an exposure of less than 4 years vs 2.3-fold (95% CI: 0.9–5.6) after a longer exposure ( P for trend = 0.07) confirmed by the results of a case–control study. Conclusion: This study confirms the overall safety of GH use in survivors of childhood cancer, which does not increase the risk of a SN. The slight excess in the risk of meningioma in patients with long-term GH treatment is non-significant and could be due to difficulties in adjustment on cranial radiation volume/dose and/or undiagnosed meningioma predisposing conditions

Risk Factors for Small Adult Height in Childhood Cancer Survivors

International audiencePURPOSE Between 10% and 20% of childhood cancer survivors (CCS) experience impaired growth, leading to small adult height (SAH). Our study aimed to quantify risk factors for SAH or growth hormone deficiency among CCS. METHODS The French CCS Study holds data on 7,670 cancer survivors treated before 2001. We analyzed self-administered questionnaire data from 2,965 CCS with clinical, chemo/radiotherapy data from medical records. SAH was defined as an adult height ≤ 2 standard deviation scores of control values obtained from a French population health study. RESULTS After exclusion of 189 CCS treated with growth hormone, 9.2% (254 of 2,776) had a SAH. Being young at the time of cancer treatment (relative risk [RR], 0.91 [95% CI, 0.88 to 0.95] by year of age), small height at diagnosis (≤ 2 standard deviation scores; RR, 6.74 [95% CI, 4.61 to 9.86]), pituitary irradiation (5-20 Gy: RR, 4.24 [95% CI, 1.98 to 9.06]; 20-40 Gy: RR, 10.16 [95% CI, 5.18 to 19.94]; and ≥ 40 Gy: RR, 19.48 [95% CI, 8.73 to 43.48]), having received busulfan (RR, 4.53 [95% CI, 2.10 to 9.77]), or > 300 mg/m 2 of lomustine (300-600 mg/m 2 : RR, 4.21 [95% CI, 1.61 to 11.01] and ≥ 600 mg/m 2 : RR, 9.12 [95% CI, 2.75 to 30.24]) were all independent risk factors for SAH. Irradiation of ≥ 7 vertebrae (≥ 15 Gy on ≥ 90% of their volume) without pituitary irradiation increased the RR of SAH by 4.62 (95% CI, 2.77 to 7.72). If patients had also received pituitary irradiation, this increased the RR by an additional factor of 1.3 to 2.4. CONCLUSION CCS are at a high risk of SAH. CCS treated with radiotherapy, busulfan, or lomustine should be closely monitored for growth, puberty onset, and potential pituitary deficiency

Risk Factors of Subsequent Central Nervous System Tumors after Childhood and Adolescent Cancers: Findings from the French Childhood Cancer Survivor Study

International audienceAbstract Background: Childhood or adolescent cancer survivors are at increased risks of subsequent primary neoplasms (SPN) of the central nervous system (CNS) after cranial irradiation. In a large multicentric cohort, we investigated clinical and therapeutic factors associated with the long-term risk of CNS SPN, and quantified the dose–response relationships. Methods: We selected all CNS SPN cases diagnosed up to 2016 among members of the French Childhood Cancer Survivor Study at least 5 years after first cancer diagnosis in 1946–2000. Four controls per case were randomly selected within the cohort and matched by sex, year of/age at first cancer diagnosis, and follow-up time. On the basis of medical and radiological reports, cumulative radiation doses received to the SPN or matched location were retrospectively estimated using mathematical phantoms. We computed conditional logistic regression models. Results: Meningioma risk significantly increased with higher radiation doses [excess OR per Gy (EOR/Gy) = 1.377; P &lt; 0.001; 86 cases; median latency time = 30 years], after adjustment for reported genetic syndromes and first CNS tumor. It was higher among youngest individuals at first cancer diagnosis, but did not vary with follow-up time. On the opposite, radiation-related glioma risk (EOR/Gy = 0.049; P = 0.11; 47 cases; median latency time = 17 years) decreased over time (P for time effect = 0.05). There was a significant association between meningioma risk and cumulative doses of alkylating agents, but no association with growth hormone therapy. Conclusions: The surveillance of patients with cranial irradiation should continue beyond 30 years after treatment. Impact: The identified risk factors may inform long-term surveillance strategies

The role of irradiated heart and left ventricular volumes in heart failure occurrence after childhood cancer

International audienceBackground: Paediatric cancer survivors have a high risk of developing cardiac diseases, and the most frequent cardiac disease is heart failure (HF). The radiation dose-volume effects in the heart and cardiac substructures have not been explored in childhood cancer survivors (CCS). Therefore, the role of irradiated heart volume in the occurrence of HF among this population remains unclear. The aims of this study were to determine the doses and irradiated volumes of the heart and left ventricle (LV) related to the risk of HF in CCS and to investigate the impact of anthracycline exposure on this risk.Methods and results: A case-control study nested in the French Childhood Cancer Survivors Study cohort. The mean heart and left ventricular doses and volumes indicators were estimated by reconstruction of individual treatments. A total of 239 HF cases and 1042 matched controls were included. The median age of HF diagnosis was 25.1 years. The median volume of the heart that received ≥ 30 Gy was 61.1% for cases and 16.9% for controls. In patients who did not receive anthracycline, the risk of HF was increased 3.6-fold when less than 10% of the LV received ≥ 30 Gy when compared to patients who were not exposed to any cardiac radiation and anthracycline.Conclusions: Small irradiated volumes of the heart or LV were significantly associated with HF risk. To the author's knowledge, this is the first study to report a dose-response relationship based on dose-volume indicators in CCS, which can be translated efficiently into current clinical practice