Increased Expression of Bcl11b Leads to Chemoresistance Accompanied by G1 Accumulation

BACKGROUND: The expression of BCL11B was reported in T-cells, neurons and keratinocytes. Aberrations of BCL11B locus leading to abnormal gene transcription were identified in human hematological disorders and corresponding animal models. Recently, the elevated levels of Bcl11b protein have been described in a subset of squameous cell carcinoma cases. Despite the rapidly accumulating knowledge concerning Bcl11b biology, the contribution of this protein to normal or transformed cell homeostasis remains open. METHODOLOGY/PRINCIPAL FINDINGS: Here, by employing an overexpression strategy we revealed formerly unidentified features of Bcl11b. Two different T-cell lines were forced to express BCL11B at levels similar to those observed in primary T-cell leukemias. This resulted in markedly increased resistance to radiomimetic drugs while no influence on death-receptor apoptotic pathway was observed. Apoptosis resistance triggered by BCL11B overexpression was accompanied by a cell cycle delay caused by accumulation of cells at G1. This cell cycle restriction was associated with upregulation of CDKN1C (p57) and CDKN2C (p18) cyclin dependent kinase inhibitors. Moreover, p27 and p130 proteins accumulated and the SKP2 gene encoding a protein of the ubiquitin-binding complex responsible for their degradation was repressed. Furthermore, the expression of the MYCN oncogene was silenced which resulted in significant depletion of the protein in cells expressing high BCL11B levels. Both cell cycle restriction and resistance to DNA-damage-induced apoptosis coincided and required the histone deacetylase binding N-terminal domain of Bcl11b. The sensitivity to genotoxic stress could be restored by the histone deacetylase inhibitor trichostatine A. CONCLUSIONS: The data presented here suggest a potential role of BCL11B in tumor survival and encourage developing Bcl11b-inhibitory approaches as a potential tool to specifically target chemoresistant tumor cells

NK-like homeodomain proteins activate NOTCH3-signaling in leukemic T-cells

<p>Abstract</p> <p>Background</p> <p>Homeodomain proteins control fundamental cellular processes in development and in cancer if deregulated. Three members of the NK-like subfamily of homeobox genes (NKLs), TLX1, TLX3 and NKX2-5, are implicated in T-cell acute lymphoblastic leukemia (T-ALL). They are activated by particular chromosomal aberrations. However, their precise function in leukemogenesis is still unclear. Here we screened further NKLs in 24 T-ALL cell lines and identified the common expression of MSX2. The subsequent aim of this study was to analyze the role of MSX2 in T-cell differentiation which may be disturbed by oncogenic NKLs.</p> <p>Methods</p> <p>Specific gene activity was examined by quantitative real-time PCR, and globally by expression profiling. Proteins were analyzed by western blot, immuno-cytology and immuno-precipitation. For overexpression studies cell lines were transduced by lentiviruses.</p> <p>Results</p> <p>Quantification of MSX2 mRNA in primary hematopoietic cells demonstrated higher levels in CD34+ stem cells as compared to peripheral blood cells and mature CD3+ T-cells. Furthermore, analysis of MSX2 expression levels in T-cell lines after treatment with core thymic factors confirmed their involvement in regulation. These results indicated that MSX2 represents an hematopoietic NKL family member which is downregulated during T-cell development and may functionally substituted by oncogenic NKLs. For functional analysis JURKAT cells were lentivirally transduced, overexpressing either MSX2 or oncogenic TLX1 and NKX2-5, respectively. These cells displayed transcriptional activation of NOTCH3-signaling, including NOTCH3 and HEY1 as analyzed by gene expression profiling and quantitative RT-PCR, and consistently attenuated sensitivity to gamma-secretase inhibitor as analyzed by MTT-assays. Furthermore, in addition to MSX2, both TLX1 and NKX2-5 proteins interacted with NOTCH-pathway repressors, SPEN/MINT/SHARP and TLE1/GRG1, representing a potential mechanism for (de)regulation. Finally, elevated expression of NOTCH3 and HEY1 was detected in primary TLX1/3 positive T-ALL cells corresponding to the cell line data.</p> <p>Conclusion</p> <p>Identification and analysis of MSX2 in hematopoietic cells implicates a modulatory role via NOTCH3-signaling in early T-cell differentiation. Our data suggest that reduction of NOTCH3-signaling by physiological downregulation of MSX2 expression during T-cell development is abrogated by ectopic expression of oncogenic NKLs, substituting MSX2 function.</p

The S phase checkpoint promotes the Smc5/6 complex dependent SUMOylation of Pol2, the catalytic subunit of DNA polymerase ε

Replication fork stalling and accumulation of single-stranded DNA trigger the S phase checkpoint, a signalling cascade that, in budding yeast, leads to the activation of the Rad53 kinase. Rad53 is essential in maintaining cell viability, but its targets of regulation are still partially unknown. Here we show that Rad53 drives the hyper-SUMOylation of Pol2, the catalytic subunit of DNA polymerase ε, principally following replication forks stalling induced by nucleotide depletion. Pol2 is the main target of SUMOylation within the replisome and its modification requires the SUMO-ligase Mms21, a subunit of the Smc5/6 complex. Moreover, the Smc5/6 complex co-purifies with Pol ε, independently of other replisome components. Finally, we map Pol2 SUMOylation to a single site within the N-terminal catalytic domain and identify a SUMO-interacting motif at the C-terminus of Pol2. These data suggest that the S phase checkpoint regulate Pol ε during replication stress through Pol2 SUMOylation and SUMO-binding abilit

Sensitivity of the Cherenkov Telescope Array for probing cosmology and fundamental physics with gamma-ray propagation

The Cherenkov Telescope Array (CTA), the new-generation ground-based observatory for γ astronomy, provides unique capabilities to address significant open questions in astrophysics, cosmology, and fundamental physics. We study some of the salient areas of γ cosmology that can be explored as part of the Key Science Projects of CTA, through simulated observations of active galactic nuclei (AGN) and of their relativistic jets. Observations of AGN with CTA will enable a measurement of γ absorption on the extragalactic background light with a statistical uncertainty below 15% up to a redshift z=2 and to constrain or detect γ halos up to intergalactic-magnetic-field strengths of at least 0.3 pG . Extragalactic observations with CTA also show promising potential to probe physics beyond the Standard Model. The best limits on Lorentz invariance violation from γ astronomy will be improved by a factor of at least two to three. CTA will also probe the parameter space in which axion-like particles could constitute a significant fraction, if not all, of dark matter. We conclude on the synergies between CTA and other upcoming facilities that will foster the growth of γ cosmology.</p

Synthesis, structure and thermal decomposition of tetra(2-pyridyl)pyrazineâI\u3csub\u3e2\u3c/sub\u3e charge-transfer complexes

In both the solid state and in solution, 2,3,5,6-tetrakis(2-€²-pyridyl)pyrazine (tpp) reacts with iodine to form charge-transfer complexes. The solid state process results in the exclusive production of a mono-I2 adduct, 3, while the solution reaction can produce both 3 and a bis-I2 adduct, 4. The X-ray crystal structure of 4 is described and a structure for 3 is proposed based upon spectroscopic evidence and molecular orbital calculations. The thermal decompositions of 3 and 4 proceed by I2 evolution at very different rates and lead to different polymorphs of tpp. The mechanism of this process is described in terms of solid state reaction theory

Objectification of Diagnostic Symptoms in Examination of Nervous System Damage by Static Interactions and Kinematic Parameters of Ankle Joint

Current diagnostics of patients' condition as well as assumed effects of the used medical diagnostic methods are a significant part of every medical treatment. The process of continuous gathering experience and comparing it with current knowledge leads to development of medical sciences and still growing effectiveness in practice. Numerous relations between particular human body systems and their interactions are very important for fast and precise diagnosis. In the paper, evaluation of the effects of neurosurgical procedures expressed as improvement of mechanical parameters of skeleton muscle system have been considered. The approach presented in the paper assumes description of results in terms of common physical units

Effect of terpenoid lactones and azadirachtin on food consumption and growth rate of Colorado potato beetle larvae, Leptinotarsa decemlineata Say

The effect of some terpenoid lactones (monocyclic δ-hydroxy-γ-lactone; bicyclic δ-hydroxy-γ-spirolactone and bicyclic δ-hydroxy-γ-lactone) and azadirachtin on feeding and growth of Leptinotarsa decemlineata Say larvae was studied. Among lactones bicyclic δ-hydroxy-γ-spirolactone showed a strong feeding deterrency. Larvae treated with this compound consumed 0.163 cm² (per larva) of potato leaves during 6 days, whereas control larvae ate 0.892 cm². When lactones were used, a slight increase in body weight was observed. Azadirachtin, in comparison with lactones, much stronger reduced food consumption and growth rate of insects.Zbadano w warunkach laboratoryjnych wpływ wybranych laktonów terpenoidowych i azadirachtyny na żerowanie, wzrost i przeżywalość larw L₁ stonki ziemniaczanej, Leptinotarsa decemlineata Say. W badaniach zastosowano monocykliczny δ-hydroksy-γ-lakton, bicykliczny δ-hydroksy-γ-spirolakton i bicykliczny δ-hydroksy-γ-lakton o skondensowanych pierścieniach – wszystkie w postaci 0,1% roztworów alkoholowych. Preparat NeemAzal-T oparty na azadirachtynie A podano w postaci wodnej zawiesiny (0,1; 0,01 i 0,001% sbcz). Użyto metody ekspozycji na traktowanych liściach ziemniaka. Stwierdzono, że spośród laktonów najsilniejsze właściwości deterentne wykazywał bicykliczny δ-hydroksy-γ-spirolakton. W jego obecności powierzchnia zjadanych liści była redukowana o 80% w porównaniu z kontrolą Pozostałe dwa laktony ograniczały żerowanie owadów o około 50% (nieco silniej bicykliczny δ-hydroksy-γ-lakton). Przy obniżonym żerowaniu obserwowano słabszy przyrost masy ciała larw oraz postępującą śmiertelność. Po 6 dniach hodowli na liściach traktowanych laktonami około 50% owadów było martwych; w próbie kontrolnej śmiertelność wynosiła 6,6%. Azadirachtyna w porównaniu z laktonami była silniejszym antyfidantem. Wśród traktowanych larw obserwowano prawie całkowite zaprzestanie żerowania, brak przyrostu masy ciała oraz wysoką śmiertelność

Ocena metabolizmu kostnego i ryzyka złamań u otyłych mężczyzn

INTRODUCTION: Obesity and metabolic syndrome are increasingly common in the adult population. There is a well- -known relationship between those two conditions and cardiovascular diseases; nonetheless, not much is known about how obesity and metabolic syndrome affect bone metabolism and fracture risk. The study aimed to assess the parameters of bone metabolism, as well as assess their relationship with the risk of fractures in obese men with central obesity and metabolic syndrome, and to compare the obtained results with those of healthy controls. MATERIAL AND METHODS: The study involved 36 obese men (body mass index – BMI ≥ 30) with central obesity (waist circumference – WC ≥ 94) and 10 healthy men as controls, aged 54–77. The FRAX (Fracture Risk Assessment Tool) calculator was used to measure the 10-year fracture risk. The levels of bone metabolism markers osteoprotegerin (OPG), C-terminal telopeptide (CTX1), and fibroblast growth factor 23 (FGF-23) were determined in the patients. RESULTS: The FRAX parameter was significantly lower (p < 0.001) in the obese men when compared to the controls. A significant negative correlation between FRAX and BMI (p < 0.001) was observed in the obese men, but not in the healthy subjects. There was also a negative correlation between FRAX and WC (p < 0.001), again only among the obese subjects. A positive correlation (p < 0.01) between FGF-23 and FRAX was found in the non-obese group. CONCLUSIONS: Obese men have a lower 10-years fracture risk compared to the healthy controls. Additionally, the increased BMI and waist circumference in the obese men were found to be associated with a reduced bone fracture risk, whereas no similar relationship in controls was observed. Moreover, higher FGF-23 levels in the healthy males was correlated with an increased 10-year fracture risk.WSTĘP: Otyłość oraz zespół metaboliczny coraz częściej występują w populacji osób dorosłych. Powszechnie znany jest związek wymienionych zaburzeń ze zwiększonym prawdopodobieństwem wystąpienia chorób układu sercowo-naczyniowego, jednakże mniej oczywisty jest ich wpływ na metabolizm kostny oraz ryzyko złamań. Celem badania była ocena parametrów metabolizmu kostnego, ich związku z ryzykiem złamań u otyłych mężczyzn z otyłością brzuszną oraz zespołem metabolicznym, a także porównanie uzyskanych wyników z wynikami osób zdrowych. MATERIAŁ I METODY: W badaniu wzięło udział 36 otyłych mężczyzn (body mass index – BMI ≥ 30) ze współistniejącą otyłością trzewną (obwód talii – waist circumference – WC ≥ 94) oraz 10 zdrowych mężczyzn z grupy kontrolnej, w wieku 54–77 lat. Do oceny ryzyka złamań zastosowano kalkulator FRAX (Fracture Risk Assessment Tool). U pacjentów oznaczono stężenia markerów metabolizmu kostnego: osteoprotegeryny (OPG), C-końcowego usieciowanego telopeptydu łańcucha kolagenu typu I (CTX1) oraz czynnika wzrostu fibroblastów 23 (fibroblast growth factor 23 – FGF-23). WYNIKI: U osób otyłych FRAX był istotnie niższy (p < 0,001) niż w grupie kontrolnej. Zaobserwowano ujemną korelację między FRAX i BMI (p < 0,001) u otyłych mężczyzn. U zdrowych osób taka korelacja nie wystąpiła. Jedynie u osób otyłych stwierdzono również ujemną korelację między FRAX i WC (p < 0,001). Obecnej w grupie osób zdrowych pozytywnej korelacji (p < 0,01) między FGF-23 i FRAX nie obserwowano u otyłych mężczyzn. WNIOSKI: U otyłych mężczyzn stwierdzono mniejsze 10-letnie ryzyko złamań w porównaniu z osobami zdrowymi. Dodatkowo wykazano, że w grupie pacjentów otyłych większe BMI oraz obwód talii wiązały się z mniejszym ryzykiem złamań kości, natomiast u osób bez otyłości taka zależność nie występowała. Ponadto u zdrowych mężczyzn większe stężenie FGF-23 było skorelowane ze zwiększonym 10-letnim ryzykiem złamań

Synthesis, structure and thermal decomposition of nitrogen-iodine charge-transfer complexes

Dipyridylquinoxaline (dpq), 4-cyanopyridine (4-CNpy), 4,4-€²-bipyridine (4,4-€²-bpy) and quinoxaline form n-†’σ* charge-transfer complexes with iodine (I2), in which the N-·- -·- -·I distance 2.532(3) Ã… for dpq-·I2; 2.543(9) and 2.555(9) Ã… for 4-CNpy-·I2; 2.406(7) Ã… for 4,4-€²-bpy-·2I2; 2.92(1) and 2.95(1) Ã… for quinox-·I2] is shorter than the sum of the van der Waals radii for nitrogen (1.55 Ã…) and iodine (1.98 Ã…). Donation of electron density into the antibonding orbital of iodine weakens the I-I bond resulting in elongation relative to the value observed in elemental iodine (2.715 Ã…). Dpq, 4-CNpy and 4,4-€²-bpy form molecular adducts, while quinoxaline forms a polymeric species in which there are interactions at both ends of the I2 molecule. The type of complex which forms depends on the nucleophilic character of the donor (and its corresponding effect of the I2 molecule) and on the lattice energy of the complex. The strength of the N-·- -·- -·I interaction in each of the reported complexes has been investigated by X-ray crystallographic analysis and vibrational spectroscopy (far-IR). All of the complexes undergo thermal decomposition involving loss of I2, and their lattice energy, as a function of thermal stability, has been explored