Regulation of NF-κB signaling by caspases and MALT1 paracaspase

Caspases are intracellular proteases that are best known for their function in apoptosis signaling. It has become evident that many caspases also function in other signaling pathways that propagate cell proliferation and inflammation, but studies on the inflammatory function of caspases have mainly been limited to caspase-1-mediated cytokine processing. Emerging evidence, however, indicates an important contribution of caspases as mediators or regulators of nuclear factor-κB (NF-κB) signaling, which plays a key role in inflammation and immunity. Much still needs to be learned about the mechanisms that govern the activation and regulation of NF-κB by caspases, and this review provides an update of this area. Whereas apoptosis signaling is dependent on the catalytic activity of caspases, they mainly act as scaffolding platforms for other signaling proteins in the case of NF-κB signaling. Caspase proteolytic activity, however, counteracts the pro-survival function of NF-κB by cleaving specific signaling molecules. A striking exception is the paracaspase mucosa-associated lymphoid tissue 1 (MALT1), whose adaptor and proteolytic activity are both needed to initiate a full blown NF-κB response in antigen-stimulated lymphocytes. Understanding the role of caspases and MALT1 in the regulation of NF-κB signaling is of high interest for therapeutic immunomodulation.     

RhoA is dispensable for skin development, but crucial for contraction and directed migration of keratinocytes

RhoA is a small guanosine-5'-triphosphatase (GTPase) suggested to be essential for cytokinesis, stress fiber formation, and epithelial cell-cell contacts. In skin, loss of RhoA was suggested to underlie pemphigus skin blistering. To analyze RhoA function in vivo, we generated mice with a keratinocyte-restricted deletion of the RhoA gene. Despite a severe reduction of cofilin and myosin light chain (MLC) phosphorylation, these mice showed normal skin development. Primary RhoA-null keratinocytes, however, displayed an increased percentage of multinucleated cells, defective maturation of cell-cell contacts. Furthermore we observed increased cell spreading due to impaired RhoA-ROCK (Rho-associated protein kinase)-MLC phosphatase-MLC-mediated cell contraction, independent of Rac1. Rho-inhibiting toxins further increased multinucleation of RhoA-null cells but had no significant effect on spreading, suggesting that RhoB and RhoC have partially overlapping functions with RhoA. Loss of RhoA decreased directed cell migration in vitro caused by reduced migration speed and directional persistence. These defects were not related to the decreased cell contraction and were independent of ROCK, as ROCK inhibition by Y27632 increased directed migration of both control and RhoA-null keratinocytes. Our data indicate a crucial role for RhoA and contraction in regulating cell spreading and a contraction-independent function of RhoA in keratinocyte migration. In addition, our data show that RhoA is dispensable for skin development.     

Sounds Scary? Lack of Habituation following the Presentation of Novel Sounds

Background

Animals typically show less habituation to biologically meaningful sounds than to novel signals. We might therefore expect that acoustic deterrents should be based on natural sounds.

Methodology

We investigated responses by western grey kangaroos (Macropus fulignosus) towards playback of natural sounds (alarm foot stomps and Australian raven (Corvus coronoides) calls) and artificial sounds (faux snake hiss and bull whip crack). We then increased rate of presentation to examine whether animals would habituate. Finally, we varied frequency of playback to investigate optimal rates of delivery.

Principal Findings

Nine behaviors clustered into five Principal Components. PC factors 1 and 2 (animals alert or looking, or hopping and moving out of area) accounted for 36% of variance. PC factor 3 (eating cessation, taking flight, movement out of area) accounted for 13% of variance. Factors 4 and 5 (relaxing, grooming and walking; 12 and 11% of variation, respectively) discontinued upon playback. The whip crack was most evocative; eating was reduced from 75% of time spent prior to playback to 6% following playback (post alarm stomp: 32%, raven call: 49%, hiss: 75%). Additionally, 24% of individuals took flight and moved out of area (50 m radius) in response to the whip crack (foot stomp: 0%, raven call: 8% and 4%, hiss: 6%). Increasing rate of presentation (12x/min ×2 min) caused 71% of animals to move out of the area.

Conclusions/Significance

The bull whip crack, an artificial sound, was as effective as the alarm stomp at eliciting aversive behaviors. Kangaroos did not fully habituate despite hearing the signal up to 20x/min. Highest rates of playback did not elicit the greatest responses, suggesting that ‘more is not always better’. Ultimately, by utilizing both artificial and biological sounds, predictability may be masked or offset, so that habituation is delayed and more effective deterrents may be produced.     

Fish consumption measured during pregnancy and risk of cardiovascular diseases later in life: an observational prospective study

Previous studies have indicated a protective effect of long chain n-3 PUFAs against cardiovascular disease; however, the overall evidence remains uncertain, and there is a general lack of knowledge in the field of cardiovascular epidemiology in women. Therefore, the objective of this study was to explore the association between fish intake and cardiovascular disease among 7429 women from a prospective pregnancy cohort in Aarhus, Denmark, who were followed for 12-17 years. Exposure information derived from a questionnaire sent to the women in gestation week 16, and daily fish consumption was quantified based on assumptions of standard portion sizes and food tables. Information on admissions to hospital was obtained from the Danish National Patient Registry and diagnoses of hypertensive, cerebrovascular and ischaemic heart disease were used to define the outcome: cardiovascular disease. During the follow-up period 263 events of cardiovascular disease were identified. Overall, there was no association between cardiovascular disease and fish intake, confidence intervals for effect estimates in the different fish intake groups were wide, overlapped and for all but one they encompassed unity. Restricting the analysis to women who had reported the same fish intake in a questionnaire in gestation week 30 did not alter these findings. In conclusion, our data from a prospective cohort of relatively young and initially healthy women from Aarhus linked with information from registries could not substantiate a protective effect of fish intake against cardiovascular disease.     

Genetic differentiation of the Western Capercaillie highlights the importance of South-eastern Europe for understanding the species phylogeography

The Western Capercaillie (Tetrao urogallus L.) is a grouse species of open boreal or high altitude forests of Eurasia. It is endangered throughout most mountain range habitat areas in Europe. Two major genetically identifiable lineages of Western Capercaillie have been described to date: the southern lineage at the species' southernmost range of distribution in Europe, and the boreal lineage. We address the question of genetic differentiation of capercaillie populations from the Rhodope and Rila Mountains in Bulgaria, across the Dinaric Mountains to the Slovenian Alps. The two lineages' contact zone and resulting conservation strategies in this so-far understudied area of distribution have not been previously determined. The results of analysis of mitochondrial DNA control region sequences of 319 samples from the studied populations show that Alpine populations were composed exclusively of boreal lineage; Dinaric populations of both, but predominantly (96%) of boreal lineage; and Rhodope-Rila populations predominantly (>90%) of southern lineage individuals. The Bulgarian mountains were identified as the core area of the southern lineage, and the Dinaric Mountains as the western contact zone between both lineages in the Balkans. Bulgarian populations appeared genetically distinct from Alpine and Dinaric populations and exhibited characteristics of a long-term stationary population, suggesting that they should be considered as a glacial relict and probably a distinct subspecies. Although all of the studied populations suffered a decline in the past, the significantly lower level of genetic diversity when compared with the neighbouring Alpine and Bulgarian populations suggests that the isolated Dinaric capercaillie is particularly vulnerable to continuing population decline. The results are discussed in the context of conservation of the species in the Balkans, its principal threats and legal protection status. Potential conservation strategies should consider the existence of the two lineages and their vulnerable Dinaric contact zone and support the specificities of the populations.     

Die gegenseitige Wirkung genotypischer Faktoren

Ohne Zusammenfassung     

Pharmacological and neurochemical characterization of the involvement of hippocampal adrenoreceptor subtypes in the modulation of acute limbic seizures

Noradrenaline exerts inhibitory effects on seizure susceptibility. Subtype selective agonists and antagonists were used to identify the anticonvulsant hippocampal adrenoreceptors. Intrahippocampal dialysis was used for administration of all compounds, including pilocarpine for limbic seizure induction, and as the neurotransmitter sampling tool. The noradrenaline reuptake inhibitor maprotiline mediated anticonvulsant effects, associated with dose-dependent increases in extracellular hippocampal noradrenaline, dopamine and GABA levels. At high concentrations, maprotiline produced proconvulsant effects associated with high levels of noradrenaline, dopamine and glutamate. Maprotiline's anticonvulsant effect was blocked by administration of either a selective α(2) - and β(2) -antagonist. α(2) -Antagonist administration with maprotiline was associated with a further increase in noradrenaline and dopamine from maprotiline alone; whereas β(2) -antagonist administered with maprotiline inhibited the dopamine increases produced by maprotiline. α(1A) -Antagonism blocked the GABA-ergic but not the anticonvulsive effect of maprotiline. These results were confirmed as combined but not separate α(2) - and β(2) -adrenoreceptor stimulation, using selective agonists, inhibited limbic seizures. Interestingly, α(1A) -receptor stimulation and α(1D) -antagonism alone also inhibited seizures associated with respectively significant hippocampal GABA increases and glutamate decreases. The main findings of this study are that (i) increased hippocampal noradrenergic neurotransmission inhibits limbic seizures via combined α(2) - and β(2) -receptor activation and (ii) α(1A) - and α(1D) -adrenoreceptors mediate opposite effects on hippocampal excitability.     

Analysis of posttranslational modifications of proteins by tandem mass spectrometry

Protein activity and turnover is tightly and dynamically regulated in living cells. Whereas the three-dimensional protein structure is predominantly determined by the amino acid sequence, posttranslational modification (PTM) of proteins modulates their molecular function and the spatial-temporal distribution in cells and tissues. Most PTMs can be detected by protein and peptide analysis by mass spectrometry (MS), either as a mass increment or a mass deficit relative to the nascent unmodified protein. Tandem mass spectrometry (MS/MS) provides a series of analytical features that are highly useful for the characterization of modified proteins via amino acid sequencing and specific detection of posttranslationally modified amino acid residues. Large-scale, quantitative analysis of proteins by MS/MS is beginning to reveal novel patterns and functions of PTMs in cellular signaling networks and biomolecular structures.