Female- and male-specific signals of quality in the barn owl

Most bird studies of female signalling have been confined to species in which females display a male-ornament in a vestigial form. However, a great deal of benefit may be gained from considering phenotypic traits that are specific to females. This is because (1) sex-specific traits may signal sex-specific qualities and (2) females may develop a male-ornament not because they are selected to do so, but because fathers transmit to daughters the underlying genes for its expression (genetic correlation between the sexes). We investigated these two propositions in the barn owl Tyto alba, a species in which male plumage is lighter in colour and less marked with black spots than that of females. Firstly, we present published evidence that female plumage spottiness reflects parasite resistance ability. We also show that male plumage coloration is correlated with reproductive success, male feeding rate and heart mass. Secondly, cross-fostering experiments demonstrate that plumage coloration and spottiness are genetically correlated between the sexes. This implies that if a given trait value is selected in one sex, the other sex will indirectly evolve towards a similar value. This prediction is supported by the observation that female plumage coloration and spottiness resembled that of males, in comparisons at the level of Tyto alba alba populations, Tyto alba subspecies and Tyto species. Our results therefore support the hypothesis that sex-specific traits signal sex-specific qualities and that a gene for a sex-specific trait can be expressed in the other sex as the consequence of a genetic correlation between the sexes.

Protease-activated receptor 2 signalling promotes dendritic cell antigen transport and T-cell activation in vivo.

Deficiency of protease-activated receptor-2 (PAR2) modulates inflammation in several models of inflammatory and autoimmune disease, although the underlying mechanism(s) are not understood. PAR2 is expressed on endothelial and immune cells, and is implicated in dendritic cell (DC) differentiation. We investigated in vivo the impact of PAR2 activation on DCs and T cells in PAR2 wild-type (WT) and knockout (KO) mice using a specific PAR2 agonist peptide (AP2). PAR2 activation significantly increased the frequency of mature CD11c(high) DCs in draining lymph nodes 24 hr after AP2 administration. Furthermore, these DCs exhibited increased expression of major histocompatibility complex (MHC) class II and CD86. A significant increase in activated (CD44(+) CD62(-)) CD4(+) and CD8(+) T-cell frequencies was also observed in draining lymph nodes 48 hr after AP2 injection. No detectable change in DC or T-cell activation profiles was observed in the spleen. The influence of PAR2 signalling on antigen transport to draining lymph nodes was assessed in the context of delayed-type hypersensitivity. PAR2 WT mice that were sensitized by skin-painting with fluorescein isothiocyanate (FITC) to induce delayed-type hypersensitivity possessed elevated proportion of FITC(+) DCs in draining lymph nodes 24 hr after FITC painting when compared with PAR2 KO mice (0.95% versus 0.47% of total lymph node cells). Collectively, these results demonstrate that PAR2 signalling promotes DC trafficking to the lymph nodes and subsequent T-cell activation, and thus provides an explanation for the pro-inflammatory effect of PAR2 in animal models of inflammation.

Serum and CSF levels of neuron-specific enolase (NSE) in cardiac surgery with cardiopulmonary bypass: a marker of brain injury?

We investigated whether neuron-specific enolase (NSE) in serum or cerebrospinal fluid (CSF) reflects subtle or manifest brain injury in children undergoing cardiac surgery using cardiopulmonary bypass (CPB). NSE was measured in serum (s-NSE) before, and up to, 102 h after surgery in 27 children undergoing cardiac surgery with CPB. In 11 children, CSF-NSE was also measured 48 or 66 h post-surgery. As erythrocytes contain NSE, hemoglobin concentration in the samples was determined spectrophotometrically at 550 nm (cut-off limit: absorbance 0.4 = 560 mg/l) in 14 children and in a further 13 children by spectroscopic multicomponent analysis (cut-off limit 5 micromol/l = 80 mg/l). One hundred and one of 214 post-operative serum samples (47%) had to be discarded because of hemolysis (18% spectrophotometrically at 550 nm and 88% with spectroscopic multicomponent analysis). On the first and second post-operative day, the median s-NSE values were significantly higher when compared with samples taken after 54 h or longer (P = 0.008 and P = 0.002). All CSF-NSE levels were within the normal range and below the s-NSE measured in the same patient. Although in our study elevated s-NSE seems to indicate brain injury in CPB-surgery, the low concentration of NSE in the post-operative CSF of 11 children puts the neuronal origin of s-NSE in question. NSE from other non-neuronal tissues probably contributes to the elevated s-NSE. Additionally, normal post-operative CSF-NSE values in two children with post-operative neurological sequelae might question the predictive value of CSF-NSE with regard to brain injury.

Neurochemical profile of the developing mouse cortex determined by in vivo 1H NMR spectroscopy at 14.1 T and the effect of recurrent anaesthesia.

The neurochemical profile of the cortex develops in a region and time specific manner, which can be distorted by psychiatric and other neurological pathologies. Pre-clinical studies often involve experimental mouse models. In this study, we determined the neurochemical profile of C57BL/6 mice in a longitudinal study design to provide a reference frame for the normal developing mouse cortex. Using in vivo proton NMR spectroscopy at 14 T, we measured the concentrations of 18 metabolites in the anterior and posterior cortex on postnatal days (P) 10, 20, 30, 60 and 90. Cortical development was marked by alterations of highly concentrated metabolites, such as N-acetylaspartate, glutamate, taurine and creatine. Regional specificity was represented by early variations in the concentration of glutamine, aspartate and choline. In adult animals, regional concentration differences were found for N-acetylaspartate, creatine and myo-inositol. In this study, animals were exposed to recurrent isoflurane anaesthesia. Additional experiments showed that the latter was devoid of major effects on behaviour or cortical neurochemical profile. In conclusion, the high sensitivity and reproducibility of the measurements achieved at 14 T allowed us to identify developmental variations of cortical areas within the mouse cortex.

Improving binding affinity and stability of peptide ligands by substituting glycines with D-amino acids.

Improving the binding affinity and/or stability of peptide ligands often requires testing of large numbers of variants to identify beneficial mutations. Herein we propose a type of mutation that promises a high success rate. In a bicyclic peptide inhibitor of the cancer-related protease urokinase-type plasminogen activator (uPA), we observed a glycine residue that has a positive ϕ dihedral angle when bound to the target. We hypothesized that replacing it with a D-amino acid, which favors positive ϕ angles, could enhance the binding affinity and/or proteolytic resistance. Mutation of this specific glycine to D-serine in the bicyclic peptide indeed improved inhibitory activity (1.75-fold) and stability (fourfold). X-ray-structure analysis of the inhibitors in complex with uPA showed that the peptide backbone conformation was conserved. Analysis of known cyclic peptide ligands showed that glycine is one of the most frequent amino acids, and that glycines with positive ϕ angles are found in many protein-bound peptides. These results suggest that the glycine-to-D-amino acid mutagenesis strategy could be broadly applied.

In vivo quantification of neuro-glial metabolism and glial glutamate concentration using 1H-[13C] MRS at 14.1T.

Astrocytes have recently become a major center of interest in neurochemistry with the discoveries on their major role in brain energy metabolism. An interesting way to probe this glial contribution is given by in vivo (13) C NMR spectroscopy coupled with the infusion labeled glial-specific substrate, such as acetate. In this study, we infused alpha-chloralose anesthetized rats with [2-(13) C]acetate and followed the dynamics of the fractional enrichment (FE) in the positions C4 and C3 of glutamate and glutamine with high sensitivity, using (1) H-[(13) C] magnetic resonance spectroscopy (MRS) at 14.1T. Applying a two-compartment mathematical model to the measured time courses yielded a glial tricarboxylic acid (TCA) cycle rate (Vg ) of 0.27 ± 0.02 μmol/g/min and a glutamatergic neurotransmission rate (VNT ) of 0.15 ± 0.01 μmol/g/min. Glial oxidative ATP metabolism thus accounts for 38% of total oxidative metabolism measured by NMR. Pyruvate carboxylase (VPC ) was 0.09 ± 0.01 μmol/g/min, corresponding to 37% of the glial glutamine synthesis rate. The glial and neuronal transmitochondrial fluxes (Vx (g) and Vx (n) ) were of the same order of magnitude as the respective TCA cycle fluxes. In addition, we estimated a glial glutamate pool size of 0.6 ± 0.1 μmol/g. The effect of spectral data quality on the fluxes estimates was analyzed by Monte Carlo simulations. In this (13) C-acetate labeling study, we propose a refined two-compartment analysis of brain energy metabolism based on (13) C turnover curves of acetate, glutamate and glutamine measured with state of the art in vivo dynamic MRS at high magnetic field in rats, enabling a deeper understanding of the specific role of glial cells in brain oxidative metabolism. In addition, the robustness of the metabolic fluxes determination relative to MRS data quality was carefully studied.

Role of the epithelial sodium channel (ENaC) and its positive regulator, the channel-activating protease 1 (CAP1) in skin

Summary: The mammalian epidermis is a pluristratified epithelium composed of 90% keratinocytes, and its main function is to serve as barrier for the body. The epithelial sodium channel (ENaC), formed by three homologous subunits α, β and γ is found in a variety of epithelia including epidermis. Previous studies showed that ENaC modulates different aspects of epidermal differentiation, such as synthesis of differentiation-specific proteins and lipid secretion. ENaC plays also a critical role in sodium homeostasis of renal and pulmonary epithelia, and its activity is thereby well controlled by hormones and non-hormonal factors, such as the serine protease CAP1 (channel-activating protease 1), also termed prostasin encoded by Prss8 gene. Serine proteases are proteolytic enzymes involved in numerous physiological and pathological processes in the epidermis. In order to evaluate the role of β and γENaC in epidermis, we analyzed the skin phenotype of β and γENaC null mutant (βENaC-/- and γENaC-/-) mice in comparison with the phenotype of αENaC-deficient mice. Furthermore, keratin14-specific CAP1-deficient mice (Prss8lox/Δ /K14-Cre) were generated in order to unveil the role of the serine protease CAP1 in epidermal development and function. This study reveals that the skin phenotype of βENaC and γENaC null mutant mice is less severe than the one of αENaC-deficient mice. However, all these mice present a common premature lipid secretion in the mid-granular layer of the epidermis. Further, the composition of the lipids of the stratum corneum in αENaC-deficient mice is strongly altered, suggesting that epidermal barrier function is compromised. K14-specific CAP1-deficient newborn mice are born at the expected Mendelian ratio, but die soon after birth, showing that CAP1 is required for postnatal survival. The epidermis of these mice exhibits striking malformations of the stratum corneum showing hyperkeratosis. These defects seriously affect both inward and outward epidermal barrier function, leading to rapid and fatal dehydration. As in αENaC-deficient mice, the lipid composition of the stratum corneum of K14-specific CAP1-deficient mice is disturbed. Furthermore, lack of CAP1 leads to the selective loss of filaggrin monomers, important for keratins aggregation and skin moisturization, and to an increased of aberrant profilaggrin precursors. In conclusion, both ENaC and CAP1 expression in the epidermis are crucial for keratinocyte differentiation processes and/or barrier function. Since the abnormalities in K14-specific CAP1-deficient mice resemble key features of human skin ichthyosis, in particular Harlequin ichthyosis, the study of ENaC and CAP1 mutant mice might allow new insights into mechanisms underlying skin diseases. Résumé: L'épiderme des mammifères est un épithélium pluristratifié, protégeant le corps contre les perturbations extérieures et la déshydratation. Le canal épithélial à sodium (ENaC), formé de trois sous-unités α, β et γ, est exprimé dans de nombreux épithélia, comme l'épiderme. Des études ont montré que l'absence de la sous-unité αENaC modulait différents aspects de la différenciation des kératinocytes de l'épiderme, comme la synthèse de protéines spécifiques ou la sécrétion de lipides dans la couche granulaire de l'épiderme. ENaC joue également un rôle crucial dans l'homéostasie du sodium dans les épithélia électriquement étanches, comme l'épithélium rénal ou pulmonaire. L'activité de ENaC est par conséquent finement régulée, en partie par des hormones, mais aussi par des facteurs non-hormonaux, telle que la sérine protéase CAP1 (« channel-activating protease 1 >>) (nommée également prostasine et codée par le gène Prss8). Le but de ce travail a donc été d'étudier le rôle des sous-unités β et γENaC dans l'épiderme en comparaison avec celui de la sous-unité α en utilisant des souris mutantes βENaC-/- et γENaC-/-. Dans un deuxième temps, le phénotype d'une souris chez qui CAP1 a été spécifiquement invalidé dans l'épiderme (Prsslox/Δ/K14-Cre) a été analysé, dans le but de mettre en évidence le rôle de cette protéase dans l'épiderme. Comme déjà montré pour les souris αENaC-/-, la sécrétion des lipides dans la couche granulaire de l'épiderme des souris βENaC-/- et γENaC-/- est prématurée. Cependant, l'hyperplasie et l'expression anormale des protéines marqueurs de la différenciation présents chez les souris αENaC-/- n'ont pas été observés dans l'épiderme des souris βENaC-/- et γENaC-/-. La composition lipidique de la couche cornée des souris αENaC-/- est fortement altérée suggérant que la fonction de barrière de l'épiderme de ces souris est compromise. Les souris mutantes CAP1 ont quant à elles révélé des malformations sévères de leur couche cornée, affectant la fonction de barrière de leur épiderme et conduisant à la mort de ces souris par déshydratation quelques jours après leur naissance. De plus, la composition en lipides de la couche cornée ainsi que la taille des cellules cornées, les cornéocytes, de ces souris sont modifiées par rapport aux souris contrôles. L'invalidation de la protéine CAP1 dans l'épiderme conduit aussi à la perte de la filaggrine, une protéine cruciale pour l'agrégation des kératines dans la couche cornée et le maintien du niveau d'hydratation de la peau, et à l'accumulation de ses précurseurs. En conclusion, l'expression de ENaC et de CAP1 est cruciale pour la différenciation de l'épiderme et/ou sa fonction de barrière. De plus, le phénotype des souris mutantes CAP1 présente des caractéristiques qui ressemblent à celles observées dans certaines pathologies humaines cutanées, comme l'ichthyose d'Harlequin. L'étude des souris mutantes ENaC et CAP1 pourrait donc apporter de nouvelles connaissances dans les mécanismes impliqués dans l'ichthyose d'Harlequin ou d'autres maladies de la peau chez l'homme. Résumé tout public: La peau est le plus grand organe vital du corps humain. Sa fonction principale est de protéger le corps comme une barrière, contre les agressions extérieures et la déshydratation. De nombreuses maladies de la peau résultent d'une perte de fonction de cette barrière. Bien que les pathologies cutanées soient très bien décrites, leur cause génétique n'est en général pas encore connue. La souris est alors un modèle de choix pour la recherche fondamentale. En effet, grâce aux progrès récents de la science, le génome de la souris peut aujourd'hui être modifié dans le but d'étudier le rôle de nombreuses protéines. Dans différents organes, comme le rein et le poumon, le canal épithélial à sodium (ENaC), composé de trois sous-unités protéiques homologues (α, β, et γ), joue un rôle essentiel dans la réabsorption du sodium. L'activité de ENaC est régulée par de nombreux facteurs hormonaux et non-hormonaux, telle que la protéase CAP1 (« channel-activating protease 1 »). L'invalidation de la sous-unité αENaC chez la souris a permis de montrer que dans la peau, le canal ENaC est impliqué dans la différenciation des cellules de l'épiderme et la croissance des poils. Durant ce travail, le phénotype des souris chez qui la protéine βENaC, γENaC ou CAP1 a été invalidée (souris mutantes), a été étudié dans le but de mieux comprendre le rôle des sous-unités du canal ENaC et de son régulateur CAP1 dans la peau. Les résultats de ce projet ont montré que les souris mutantes βENaC et γENaC présentent un épiderme anormal avec une synthèse prématurée de lipides dans la couche granulaire, suggérant l'implication de ENaC dans la fonction de barrière de la peau. De plus, quand CAP1 est invalidé de manière totale chez les souris, le développement embryonnaire est perturbé et ces souris meurent avant la naissance. CAP1 a donc été invalidé spécifiquement dans l'épiderme des souris. Ces souris mutantes « épiderme-spécifique » naissent normalement, mais meurent peu après la naissance de déshydratation. La couche superficielle de l'épiderme, appelée couche cornée, de ces souris est malformée et ne confère plus à la peau sa fonction de barrière. De plus, les composants de la couche cornée, les cellules cornées entourées de lipides, sont sévèrement altérés. Le phénotype de ces souris ressemble aux caractéristiques présentes chez les patients atteints d'ichthyoses, en particulier l'ichthyose d'Harlequin. En conclusion, le canal ENaC ainsi que son régulateur CAP1 jouent un rôle clé dans les processus de différenciation de l'épiderme et/ou de sa fonction de barrière. De plus, les souris mutantes pour CAP1 et ENaC se révéleront peut-être comme des modèles appropriés dans l'étude de l'ichthyose d'Harlequin ou d'autres maladies cutanées.

Absolute height-specific thresholds to identify elevated blood pressure in children.

OBJECTIVE: : Identification of children with elevated blood pressure (BP) is difficult because of the multiple sex, age, and height-specific thresholds to define elevated BP. We propose a simple set of absolute height-specific BP thresholds and evaluate their performance to identify children with elevated BP in two different populations. METHODS: : Using the 95th sex, age, and relative-height BP US thresholds to define elevated BP in children (standard criteria), we derived a set of (non sex- and non age-specific) absolute height-specific BP thresholds for 11 height categories by 10 cm increments. Using data from large school-based surveys conducted in Switzerland (N = 5207; 2621 boys, 2586 girls; age range: 10.1-14.9 years) and in the Seychelles (N = 25 759; 13 048 boys, 12 711 girls; age range: 4.4-18.8 years), we evaluated the performance of these height-specific thresholds to identify children with elevated BP. We also derived sex-specific absolute height-specific BP thresholds and compared their performance. RESULTS: : In the Swiss and the Seychelles surveys, the prevalence of elevated BP (standard criteria) was 11.4 and 9.1%, respectively. The height-specific thresholds to identify elevated BP had a sensitivity of 80 and 84%, a specificity of 99 and 99%, a positive predictive value of 92 and 91%, and a negative predictive value of 97 and 98%, respectively. Performance of sex-specific absolute height-specific BP thresholds was similar. CONCLUSION: : A simple table of height-specific BP thresholds allowed identifying children with elevated BP with high sensitivity and excellent specificity.

Association of socioeconomic status with overall and cause specific mortality in the republic of seychelles : results from a cohort study in the african region

BACKGROUND: Low socioeconomic status (SES) is consistently associated with higher mortality in high income countries. Only few studies have assessed this association in low and middle income countries, mainly because of sparse reliable mortality data. This study explores SES differences in overall and cause-specific mortality in the Seychelles, a rapidly developing small island state in the African region. METHODS: All deaths have been medically certified over more than two decades. SES and other lifestyle-related risk factors were assessed in a total of 3246 participants from three independent population-based surveys conducted in 1989, 1994 and 2004. Vital status was ascertained using linkage with vital statistics. Occupational position was the indicator of SES used in this study and was assessed with the same questions in the three surveys. RESULTS: During a mean follow-up of 15.0 years (range 0-23 years), 523 participants died (overall mortality rate 10.8 per 1000 person-years). The main causes of death were cardiovascular disease (CVD) (219 deaths) and cancer (142 deaths). Participants in the low SES group had a higher mortality risk for overall (HR = 1.80; 95% CI: 1.24-2.62), CVD (HR = 1.95; 1.04-3.65) and non-cancer/non-CVD (HR = 2.14; 1.10-4.16) mortality compared to participants in the high SES group. Cancer mortality also tended to be patterned by SES (HR = 1.44; 0.76-2.75). Major lifestyle-related risk factors (smoking, heavy drinking, obesity, diabetes, hypertension, hypercholesterolemia) explained a small proportion of the associations between low SES and all-cause, CVD, and non-cancer/non-CVD mortality. CONCLUSIONS: In this population-based study assessing social inequalities in mortality in a country of the African region, low SES (as measured by occupational position) was strongly associated with overall, CVD and non-cancer/non-CVD mortality. Our findings support the view that the burden of non-communicable diseases may disproportionally affect people with low SES in low and middle income countries.

Decreased specific CD8+ T cell cross-reactivity of antigen recognition following vaccination with Melan-A peptide.

The aim of T cell vaccines is the expansion of antigen-specific T cells able to confer immune protection against pathogens or tumors. Although increase in absolute cell numbers, effector functions and TCR repertoire of vaccine-induced T cells are often evaluated, their reactivity for the cognate antigen versus their cross-reactive potential is rarely considered. In fact, little information is available regarding the influence of vaccines on T cell fine specificity of antigen recognition despite the impact that this feature may have in protective immunity. To shed light on the cross-reactive potential of vaccine-induced cells, we analyzed the reactivity of CD8(+) T cells following vaccination of HLA-A2(+) melanoma patients with Melan-A peptide, incomplete Freund's adjuvant and CpG-oligodeoxynucleotide adjuvant, which was shown to induce strong expansion of Melan-A-reactive CD8(+) T cells in vivo. A collection of predicted Melan-A cross-reactive peptides, identified from a combinatorial peptide library, was used to probe functional antigen recognition of PBMC ex vivo and Melan-A-reactive CD8(+) T cell clones. While Melan-A-reactive CD8(+) T cells prior to vaccination are usually constituted of widely cross-reactive naive cells, we show that peptide vaccination resulted in expansion of memory T cells displaying a reactivity predominantly restricted to the antigen of interest. Importantly, these cells are tumor-reactive.

Determinants for membrane association of the hepatitis C virus NS2 protease domain.

Hepatitis C virus (HCV) nonstructural protein 2 (NS2) is required for HCV polyprotein processing and particle assembly. It comprises an N-terminal membrane domain and a C-terminal, cytosolically oriented protease domain. Here, we demonstrate that the NS2 protease domain itself associates with cellular membranes. A single charged residue in the second α-helix of the NS2 protease domain is required for proper membrane association, NS2 protein stability, and efficient HCV polyprotein processing.

Neurochemical profile of the mouse hypothalamus using in vivo 1H MRS at 14.1T.

The hypothalamus plays an essential role in the central nervous system of mammals by among others regulating glucose homeostasis, food intake, temperature, and to some extent blood pressure. Assessments of hypothalamic metabolism using, e.g. (1)H MRS in mouse models can provide important insights into its function. To date, direct in vivo (1)H MRS measurements of hypothalamus have not been reported. Here, we report that in vivo single voxel measurements of mouse hypothalamus are feasible using (1)H MRS at 14.1T. Localized (1)H MR spectra from hypothalamus were obtained unilaterally (2-2.2 microL, VOI) and bilaterally (4-4.4 microL) with a quality comparable to that of hippocampus (3-3.5 microL). Using LCModel, a neurochemical profile consisting of 21 metabolites was quantified for both hypothalamus and hippocampus with most of the Cramér-Rao lower bounds within 20%. Relative to the hippocampus, the hypothalamus was characterized by high gamma-aminobutryric acid and myo-inositol, and low taurine concentrations. When studying transgenic mice with no glucose transporter isoform 8 expressed, small metabolic changes were observed, yet glucose homeostasis was well maintained. We conclude that a specific neurochemical profile of mouse hypothalamus can be measured by (1)H MRS which will allow identifying and following metabolic alterations longitudinally in the hypothalamus of genetic modified models.

Content-specific gender differences in emotion ratings from early to late adulthood.

The investigation of gender differences in emotion has attracted much attention given the potential ramifications on our understanding of sexual differences in disorders involving emotion dysregulation. Yet, research on content-specific gender differences across adulthood in emotional responding is lacking. The aims of the present study were twofold. First, we sought to investigate to what extent gender differences in the self-reported emotional experience are content specific. Second, we sought to determine whether gender differences are stable across the adult lifespan. We assessed valence and arousal ratings of 14 picture series, each of a different content, in 94 men and 118 women aged 20 to 81. Compared to women, men reacted more positively to erotic images, whereas women rated low-arousing pleasant family scenes and landscapes as particularly positive. Women displayed a disposition to respond with greater defensive activation (i.e., more negative valence and higher arousal), in particular to the most arousing unpleasant contents. Importantly, significant interactions between gender and age were not found for any single content. This study makes a novel contribution by showing that gender differences in the affective experiences in response to different contents persist across the adult lifespan. These findings support the "stability hypothesis" of gender differences across age.

The E3 ubiquitin ligase Itch regulates sorting nexin 9 through an unconventional substrate recognition domain.

The level of intracellular proteins is mainly regulated through modifications by ubiquitin ligases that target them for degradation. Members of the NEDD4 family of E3 ubiquitin ligases, such as Itch (atrophin-1 interacting protein 4), possess up to four WW domains for specific association with PY motif-containing substrates. We have identified sorting nexin 9 (SNX9), a protein involved in endocytic processes, as a new substrate of Itch. Itch ubiquitylates SNX9 and regulates intracellular SNX9 levels. Using truncated proteins, we found that the interaction with SNX9 is mediated by the proline-rich domain (PRD) of Itch, a domain distinct from the conventional WW recognition domain, and the SH3 domain of SNX9. Interaction with the PRD of Itch is essential for SNX9 ubiquitylation and degradation. Furthermore, this effect is specific for Itch, as NEDD4, a related PRD-containing E3 ligase, does not bind SNX9. SNX18, a second member of the SNX family containing an SH3 domain, was also found to bind to Itch. Our results indicate that the pool of substrates of NEDD4 family E3 ubiquitin ligases extends beyond proteins containing PY motifs.

The channel-activating protease CAP1/Prss8 is required for placental labyrinth maturation.

The serine protease CAP1/Prss8 is crucial for skin barrier function, lung alveolar fluid clearance and has been unveiled as diagnostic marker for specific cancer types. Here, we show that a constitutive knockout of CAP1/Prss8 leads to embryonic lethality. These embryos presented no specific defects, but it is during this period, and in particular at E13.5, that wildtype placentas show an increased expression of CAP1/Prss8, thus suggesting a placental defect in the knockout situation. The placentas of knockout embryos exhibited significantly reduced vascular development and incomplete cellular maturation. In contrary, epiblast-specific deletion of CAP1/Prss8 allowed development until birth. These CAP1/Prss8-deficient newborns presented abnormal epidermis, and died soon after birth due to impaired skin function. We thus conclude that a late placental insufficiency might be the primary cause of embryonic lethality in CAP1/Prss8 knockouts. This study highlights a novel and crucial role for CAP1/Prss8 in placental development and function.