Mitogen activated protein kinases (MAPKs) have a docking groove that interacts with linear motifs in binding partners. To determine the structural basis of binding specificity between MAPKs and docking motifs, we quantitatively analyzed the ability of fifteen linear motifs from diverse MAPK partners to bind to c-Jun N-terminal kinase 1 (JNK1), p38α and extracellular signal-regulated kinase 2 (ERK2). Classical docking motifs mediated highly specific binding only to JNK1, and only motifs with a sequence pattern distinct from the classical MAPK binding docking motif consensus could differentiate between the topographically similar docking grooves of ERK and p38. We also solved the crystal structures for four MAPK-docking peptide complexes that represented JNK-specific, ERK-specific or ERK-and p38-selective binding modes. These structures revealed that the regions located in between consensus positions in the docking motifs showed conformational diversity. Although the consensus positions in the docking motifs served as anchor points that bound to common MAPK surface features and mostly contributed to docking in a non-discriminatory fashion, specificity was determined mainly by the conformation of the intervening region between the anchor points. These insights enabled us to successfully design peptides with tailored MAPK binding profiles by rationally changing the length and amino acid composition of docking motif regions located between anchor points. We present a coherent structural model underlying MAPK docking specificity that reveals how short linear motifs

Meiotic crossover formation involves the repair of programmed DNA double-strand breaks (DSBs) and synaptonemal complex (SC) formation. Completion of these processes must precede the meiotic divisions in order to avoid chromosome abnormalities in gametes. Enduring key questions in meiosis have been how meiotic progression and crossover formation are coordinated, whether inappropriate asynapsis is monitored, and whether asynapsis elicits prophase arrest via mechanisms that are distinct from the surveillance of unrepaired DNA DSBs. We disrupted the meiosis-specific mouse HORMAD2 (Hop1, Rev7, and Mad2 domain 2) protein, which preferentially associates with unsynapsed chromosome axes. We show that HORMAD2 is required for the accumulation of the checkpoint kinase ATR along unsynapsed axes, but not at DNA DSBs or on DNA DSBassociated chromatin loops. Consistent with the hypothesis that ATR activity on chromatin plays important roles in the quality control of meiotic prophase, HORMAD2 is required for the elimination of the asynaptic Spo11 -/-, but not the asynaptic and DSB repair-defective Dmc1 -/-oocytes. Our observations strongly suggest that HORMAD2-dependent recruitment of ATR to unsynapsed chromosome axes constitutes a mechanism for the surveillance of asynapsis. Thus, we provide convincing evidence for the existence of a distinct asynapsis surveillance mechanism that safeguards the ploidy of the mammalian germline.[Keywords: asynapsis surveillance; meiotic prophase checkpoint; ATR; HORMA domain; meiosis; aneuploidy] Supplemental material is available for this article. Received January 30, 2012; revised version accepted March 19, 2012. Orderly chromosome segregation during the first meiotic division requires that homologous maternal and paternal chromosomes (called homologs) become physically linked, thereby forming so-called bivalents during the first meiotic prophase (Page and Hawley 2003). In most organisms, including mammals, meiotic recombination generates reciprocal exchanges, called crossovers (COs), between homologous DNA sequences. Interhomolog COs and sister chromatid cohesion together form the basis of the physical linkages, called chiasmata, that connect pairs of homologs during the first meiotic metaphase. Therefore, at least one CO must form between each pair of homologs to ensure correct segregation during the first meiotic division.CO formation requires that homologs find each other. To achieve this, double-strand breaks (DSBs) are actively introduced into the genome at the beginning of prophase by the SPO11 enzyme (Keeney et al. 1997;Baudat et al. 2000;Romanienko and Camerini-Otero 2000). This is followed by the resection of DSB ends, which creates 39 ssDNA overhangs (Neale et al. 2005). The RAD51 and DMC1 recombinases bind single-stranded DSB ends and assist homology search through promoting strand invasion of resected DSB ends into homologous DNA sequences (Baudat and de Massy 2007). Several DSB ends work in parallel on each pair of homologs to ensure alignment along the full lengths of homolo...

This study reveals apelin as a novel angiogenic factor in human NSCLC. Moreover, it also provides the first evidence for a direct association of apelin expression with clinical outcome in a human cancer.

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Disturbance of rapid eye movement (REM) sleep appears early in both patients with Huntington's disease (HD) and mouse models of HD. Selective serotonin reuptake inhibitors are widely prescribed for patients with HD, and are also known to suppress REM sleep in healthy subjects. To test whether selective serotonin reuptake inhibitors can correct abnormal REM sleep and sleep-dependent brain oscillations in HD mice, we treated wild-type and symptomatic R6/2 mice acutely with vehicle and paroxetine (5, 10, and 20 mg/kg). In addition, we treated a group of R6/2 mice chronically with vehicle or paroxetine (20 mg/kg/day) for 8 weeks, with treatment starting before the onset of overt motor symptoms. During and after treatment, we recorded electroencephalo-gram/electromyogram from the mice. We found that both acute and chronic paroxetine treatment normalized REM sleep in R6/2 mice. However, only chronic paroxetine treatment prevented the emergence of abnormal low-gamma (25-45 Hz) electroencephalogram oscillations in R6/2 mice, an effect that persisted for at least 2 weeks after treatment stopped. Chronic paroxetine treatment also normalized REM sleep theta rhythm in R6/2 mice, but, interestingly, this effect was restricted to the treatment period. By contrast, acute paroxetine treatment slowed REM sleep theta rhythm in WT mice but had no effect on abnormal theta or low-gamma oscillations in R6/2 mice. Our data show that paroxetine treatment, when initiated before the onset of symptoms, corrects both REM sleep disturbances and abnormal brain oscillations, suggesting a possible mechanistic link between early disruption of REM sleep and the subsequent abnormal brain activity in HD mice.

OBJECTIVE:To determine whether the anorexigenic peptide, nesfatin-1 affects energy expenditure, and to follow the time course of its effects. DESIGN: Food intake duration, core body temperature, locomotor activity and heart rate of rats were measured by telemetry for 48 h after a single intracerebroventricular injection of 25 or 100 pmol nesfatin-1 applied in the dark or the light phase of the day. Body weight, food and water intake changes were measured daily. Furthermore, cold-responsive nesfatin-1/NUCB2 neurons were mapped in the brain. RESULTS: Nesfatin-1 reduced duration of nocturnal food intake for 2 days independently of circadian time injected, and raised body temperature immediately, or with little delay depending on the dose and circadian time applied. The body temperature remained higher during the next light phases of the 48 h observation period, and the circadian curve of temperature flattened. After light phase application, the heart rate was elevated transiently. Locomotion did not change. Daily food and water intake, as well as body weight measurements point to a potential decrease in all parameters on the first day and some degree of compensation on the second day. Cold-activated (Fos positive) nesfatin-1/NUCB2 neurones have been revealed in several brain nuclei involved in cold adaptation. Nesfatin-1 co-localised with prepro-thyrotropin-releasing hormone in cold responsive neurones of the hypothalamic paraventricular nucleus, and in neurones of the nucleus raphe pallidus and obscurus that are premotor neurones regulating brown adipose tissue thermogenesis and skin blood flow. CONCLUSION: Nesfatin-1 has a remarkably prolonged effect on food intake and body temperature. Time course of nesfatin-1's effects may be varied depending on the time applied. Many of the nesfatin-1/NUCB2 neurones are cold sensitive, and are positioned in key centres of thermoregulation. Nesfatin-1 regulates energy expenditure a far more potent way than it was recognised before making it a preferable candidate anti-obesity drug.

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