The DNA damage response mediator MDC1 directly interacts with the anaphase-promoting complex/cyclosome

MDC1 (NFBD1), a mediator of the cellular response to DNA damage, plays an important role in checkpoint activation and DNA repair. Here we identified a cross-talk between the DNA damage response and cell cycle regulation. We discovered that MDC1 binds the anaphase-promoting complex/cyclosome (APC/C), an E3 ubiquitin ligase that controls the cell cycle. The interaction is direct and is mediated by the tandem BRCA1 C-terminal domains of MDC1 and the C terminus of the Cdc27 (APC3) subunit of the APC/C. It requires the phosphorylation of Cdc27 and is enhanced after induction of DNA damage. We show that the tandem BRCA1 C-terminal domains of MDC1, known to directly bind the phosphorylated form of histone H2AX (gamma-H2AX), also bind the APC/C by the same mechanism, as phosphopeptides that correspond to the C termini of gamma-H2AX and Cdc27 competed with each other for the binding to MDC1. Our results reveal a link between the cellular response to DNA damage and cell cycle regulation, suggesting that MDC1, known to have a role in checkpoint regulation, executes part of this role by binding the APC/C.     

Functional UQCRC1 polymorphisms affect promoter activity and body lipid accumulation

Obesity and type 2 diabetes constitute leading public health problems worldwide. Studies have shown that insulin resistance affiliated with these conditions is associated with skeletal muscle lipid accumulation, while the latter is associated with mitochondrial dysfunctions. However, the initiation and regulation of mitochondrial biogenesis rely heavily on approximately 1000 nuclear-encoded mitochondrial regulatory proteins. In this study, we targeted the ubiquinol-cytochrome c reductase core protein I gene, a nuclear-encoded component of mitochondrial complex III, for its association with subcutaneous fat depth (SFD) and skeletal muscle lipid accumulation (SMLA) using cattle as a model. Four promoter polymorphisms were identified and genotyped on approximately 250 Wagyu x Limousin F2 progeny. Statistical analysis revealed that two completely linked polymorphic sites, g.13487C>T and g.13709G>C (r2 = 1), were significantly associated with both SFD (p < 0.01) and SMLA (p < 0.0001). The difference between TTCC and CCGG haplotypes was 0.178 cm for SFD and 0.624 scores for SMLA. Interestingly, the former haplotype produced higher promoter activities than the latter by 43% to 49% in three cell lines (p < 0.05). In addition to Rett syndrome and breast/ovarian cancer observed in other studies, we report evidence for the first time, to our knowledge, that overexpression of ubiquinol-cytochrome c reductase core protein I might affect mitochondrial morphology and/or physiology and lead to development of obesity and related conditions.     

Mechanisms of leukemogenesis induced by bovine leukemia virus: prospects for novel anti-retroviral therapies in human

In 1871, the observation of yellowish nodules in the enlarged spleen of a cow was considered to be the first reported case of bovine leukemia. The etiological agent of this lymphoproliferative disease, bovine leukemia virus (BLV), belongs to the deltaretrovirus genus which also includes the related human T-lymphotropic virus type 1 (HTLV-1). This review summarizes current knowledge of this viral system, which is important as a model for leukemogenesis. Recently, the BLV model has also cast light onto novel prospects for therapies of HTLV induced diseases, for which no satisfactory treatment exists so far.     

Protease-activated receptor-1 (hPar1), a survival factor eliciting tumor progression

Although ample evidence point to the central involvement of protease activated receptor-1 (PAR1) in tumor progression, little is known about the fate of the tumor when hPar1 is being silenced. We observed that hPar1 antisense clones exhibit low PAR1 levels, attenuated cell proliferation and invasion in vitro, and tumor formation in vivo. These clones showed noticeably reduced paxillin phosphorylation compared with the parental A375SM cells, whereas no change in the integrin levels was noticed. Antisense clones injected into the mice resulted in very few and only occasional small tumors, whereas advanced and vascularized tumors were observed in A375SM cells. The antisense-derived tumor sections expressed active caspase-3, increased terminal deoxynucleotidyl transferase-mediated nick-end labeling staining, and a markedly reduced proliferating cell nuclear antigen level compared with A375SM cell-derived tissue sections. Likewise, ablation of the hPar1 gene in a tetracycline-inducible hPar1 system leads to apoptosis in immature blood vessels, whereas mature vessels were unaffected. The activation of PAR1-induced pAkt/protein kinase B abrogated serum-deprived Bim(EL) induction and also markedly inhibited Bax levels. On the other hand, small interfering RNA silencing of the hPar1 gene induced the expression of Bim(EL), a direct substrate of Akt/protein kinase B and also induced expression of active caspase-9 and caspase-3. These results altogether identify PAR1 as a survival factor that protects cells from undergoing apoptosis. We conclude that whereas PAR1 gene expression correlates with tumor progression, its neutralization effectively initiates an apoptotic pathway leading at least in part to significantly reduced tumor formation.     

Asymmetric deceleration of ClpB or Hsp104 ATPase activity unleashes protein-remodeling activity

Two members of the AAA+ superfamily, ClpB and Hsp104, collaborate with Hsp70 and Hsp40 to rescue aggregated proteins. However, the mechanisms that elicit and underlie their protein-remodeling activities remain unclear. We report that for both Hsp104 and ClpB, mixtures of ATP and ATP-gammaS unexpectedly unleash activation, disaggregation and unfolding activities independent of cochaperones. Mutations reveal how remodeling activities are elicited by impaired hydrolysis at individual nucleotide-binding domains. However, for some substrates, mixtures of ATP and ATP-gammaS abolish remodeling, whereas for others, ATP binding without hydrolysis is sufficient. Remodeling of different substrates necessitates a diverse balance of polypeptide 'holding' (which requires ATP binding but not hydrolysis) and unfolding (which requires ATP hydrolysis). We suggest that this versatility in reaction mechanism enables ClpB and Hsp104 to reactivate the entire aggregated proteome after stress and enables Hsp104 to control prion inheritance.     

Finding a common motif of RNA sequences using genetic programming: the GeRNAMo system

We focus on finding a consensus motif of a set of homologous or functionally related RNA molecules. Recent approaches to this problem have been limited to simple motifs, require sequence alignment, and make prior assumptions concerning the data set. We use genetic programming to predict RNA consensus motifs based solely on the data set. Our system -- dubbed GeRNAMo (Genetic programming of RNA Motifs) -- predicts the most common motifs without sequence alignment and is capable of dealing with any motif size. Our program only requires the maximum number of stems in the motif, and if prior knowledge is available the user can specify other attributes of the motif (e.g., the range of the motif's minimum and maximum sizes), thereby increasing both sensitivity and speed. We describe several experiments using either ferritin iron response element (IRE); signal recognition particle (SRP); or microRNA sequences, showing that the most common motif is found repeatedly, and that our system offers substantial advantages over previous methods.     

Chiral separation of aliphatic primary amino alcohols as o‐phthaldialdehyde/mercaptoethanol derivatives on polysaccharide‐based chiral stationary phases

A sensitive chiral high performance liquid chromatography (HPLC) method for the determination of aliphatic primary amino alcohol isomers with o‐phthaldialdehyde/mercaptoethanol precolumn derivatization has been developed and validated. Seven chiral columns were tested in a reversed phase mode. Excellent enantioseparation with the resolution more than 2.0 was achieved on Chiralcel OJ‐3R. The effect of various chromatographic conditions including column temperature, acetonitrile content in the mobile phase, buffer pH, buffer concentration, and buffer type in the mobile phase on the retention and the selectivity was investigated. The final mobile phase consisted of binary mixture of 20mM ammonium formate solution with acetonitrile (75:25; v/v). The analyses were performed at mobile phase flow rate of 1.0 mL/min and the column temperature of 40°C. The fluorescence detection was performed at excitation wavelength of 345 nm and emission wavelength of 450 nm. The developed method was fully validated in terms of linearity, sensitivity, accuracy, precision, intermediate precision, and selectivity according to International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use guidelines using internal normalization procedure. The proposed chiral method was proved to be highly sensitive, simple, and rapid and was successfully applied to the determination of D‐Valinol content in commercially available samples of L‐Valinol.     

Aeroecology meets aviation safety: early warning systems in Europe and the Middle East prevent collisions between birds and aircraft

The aerosphere is utilized by billions of birds, moving for different reasons and from short to great distances spanning tens of thousands of kilometres. The aerosphere, however, is also utilized by aviation which leads to increasing conflicts in and around airfields as well as en‐route. Collisions between birds and aircraft cost billions of euros annually and, in some cases, result in the loss of human lives. Simultaneously, aviation has diverse negative impacts on wildlife. During avian migration, due to the sheer numbers of birds in the air, the risk of bird strikes becomes particularly acute for low‐flying aircraft, especially during military training flights. Over the last few decades, air forces across Europe and the Middle East have been developing solutions that integrate ecological research and aviation policy to reduce mutual negative interactions between birds and aircraft. In this paper we 1) provide a brief overview of the systems currently used in military aviation to monitor bird migration movements in the aerosphere, 2) provide a brief overview of the impact of bird strikes on military low‐level operations, and 3) estimate the effectiveness of migration monitoring systems in bird strike avoidance. We compare systems from the Netherlands, Belgium, Germany, Poland and Israel, which are all areas that Palearctic migrants cross twice a year in huge numbers. We show that the en‐route bird strikes have decreased considerably in countries where avoidance systems have been implemented, and that consequently bird strikes are on average 45% less frequent in countries with implemented avoidance systems in place. We conclude by showing the roles of operational weather radar networks, forecast models and international and interdisciplinary collaboration to create safer skies for aviation and birds.