Membrane phosphoinositides stabilize GPCR-arrestin complexes and offer temporal control of complex assembly and dynamics

SummaryArrestins recognize activated and phosphorylated G protein-coupled receptors (GPCRs) and are responsible for promoting acute desensitization of receptors as well as their endocytosis. As phosphatidylinositols have been shown to bind to components of the endocytic machinery, including arrestins, we examined the role of phosphoinositide (PIP) binding in GPCR-arrestin complexes. Using a PIP-binding-deficient mutant of arrestin we find that GPCRs stratify into two groups based on whether arrestin-PIP-interactions are required for arrestin recruitment to activated receptors. This requirement for arrestin-PIP-interactions depends on receptor phosphorylation, with receptors having more limited phosphorylation requiring arrestin-PIP-binding capacity. In vitro, this arrestin lipid binding functions to stabilize receptor-arrestin complexes and is crucial for promoting a core-engaged state of the complex. In the absence of a bound GPCR, PIP2, but not endosome resident PI(3)P, promotes conformational changes in arrestin that parallel activation, including movement of the finger and gate loops, but without release of the arrestin C-terminus. These results suggest a model for arrestin recruitment that depends on three components that each function to potentiate the conformation of arrestin: the GPCR core, phosphorylated GPCR C-terminus and membrane phosphoinositides. Integration of a phosphoinositide-dependence into arrestin-GPCR complex assembly provides a mechanism for release of arrestin from GPCRs with insufficient phosphorylation, allowing for their rapid recycling, while explaining how GPCRs that form stable complexes with arrestin can remain associated yet switch from desensitized to allowing G protein coupling in endosomes.

Methodological approaches to the formation of professionally oriented english lexical competence in speaking in future specialists of hotel and restaurant business

Methodological approaches to the formation of professionally oriented English lexical competence in speaking in future hotel and restaurant specialists are selected and revealed, and the principles of this process are substantiated. The essence and structure of professionally oriented English lexical competence in speaking of future specialists of hotel and restaurant business are formulated. The preconditions of vocabulary use, including terminological, are considered. It has been found, that the production of oral speech is impossible without the perception and understanding of oral speech by ear. The following approaches are described, which provide methodical and methodological substantiation of the process of formation of professionally oriented English lexical competence in speaking in future specialists of hotel and restaurant business, such as: communicative, interactive, student-centric, sociolinguistic. The peculiarities of formation of professionally oriented English lexical competence in speaking in future specialists of hotel and restaurant business on the basis of the communicative approach are outlined. The educational materials, used in the application of the communicative approach, are investigated. The interactive discourse, which is a type of communicative activity, is considered. The principles, on which this process is based, are analyzed: general methodological principles (situational; communicative activity; communicative value; immersion), specific principles speech clichés, parallel activation of visual and auditory channels of information perception). Recommendations for the optimal combination of classroom learning and extracurricular learning, including independent work with the help of network technologies using video, audio and text materials, are given. Learning outcomes are formulated on the basis of the student-centered approach, attention is focused on students' skills and competencies. On the basis of the sociolinguistic approach, the creation of educational situations for the purpose of reproduction of scenarios of professionally oriented communication of experts of hotel and restaurant business is provided. It is concluded, that the formation of professionally oriented English lexical competence in speaking in future hotel and restaurant professionals on the basis of communicative, interactive, student-centric, sociolinguistic approaches will ensure the effectiveness of this process

Prolonged and distributed processing of facial identity in the human brain

The recognition of facial identity is essential for social interactions. Despite extensive prior fMRI and EEG/MEG research on the neural representations of familiar faces, we know little about the spatio-temporal dynamics of face identity information. Therefore, we applied a novel multimodal approach, by fusioning the neuronal responses recorded in an fMRI and an EEG experiment. We analyzed the neural responses to naturally varying famous faces and traced how face identity emerges over time in different areas of the brain. We found that image invariant face identity information prevails over an extended time period (from 150 to 810 ms after stimulus onset) in the representational geometry of a broadly distributed network of parietal, temporal, and frontal areas with overlapping temporal profiles. These results challenge the current hierarchical models of face perception and suggest instead concerted and parallel activation of multiple nodes in the brain's identity coding network while processing information of familiar faces.

Bumble bee queens activate dopamine production and gene expression in nutritional signaling pathways in the brain

To explore the neuroendocrine mechanisms underlying caste-specific behavior and its evolution from primitive to advanced eusocial bees, the monoamine levels and expression of genes involved in monoamine production and signaling in the brain were compared between the castes of Bombus ignitus. Higher levels of dopamine and its related substances were found in the brains of newly emerged queens than in the brains of emerged workers. The degree of caste differences in B. ignitus was smaller than that reported in Apis mellifera, indicating a link to different social stages in the two species. There was no differential expression in genes involved in dopamine biosynthesis between castes, suggesting that the high dopamine production in queens was not largely influenced by the expression of these genes at emergence, rather it might be influenced by tyrosine supply. Genome-wide analyses of gene expression by RNA-sequencing indicated that a greater number of genes involved in nutrition were actively expressed in the brains of newly emerged queens in comparison to the emerged workers. Some of the expression was confirmed by real-time quantitative PCR. The signaling pathways driven by the expression of these genes may be associated with dopamine signaling or the parallel activation of dopamine production.

A dynamic role for dopamine receptors in the control of mammalian spinal networks

Dopamine is well known to regulate movement through the differential control of direct and indirect pathways in the striatum that express D1 and D2 receptors respectively. The spinal cord also expresses all dopamine receptors; however, how the specific receptors regulate spinal network output in mammals is poorly understood. We explore the receptor-specific mechanisms that underlie dopaminergic control of spinal network output of neonatal mice during changes in spinal network excitability. During spontaneous activity, which is a characteristic of developing spinal networks operating in a low excitability state, we found that dopamine is primarily inhibitory. We uncover an excitatory D1-mediated effect of dopamine on motoneurons and network output that also involves co-activation with D2 receptors. Critically, these excitatory actions require higher concentrations of dopamine; however, analysis of dopamine concentrations of neonates indicates that endogenous levels of spinal dopamine are low. Because endogenous levels of spinal dopamine are low, this excitatory dopaminergic pathway is likely physiologically-silent at this stage in development. In contrast, the inhibitory effect of dopamine, at low physiological concentrations is mediated by parallel activation of D2, D3, D4 and α2 receptors which is reproduced when endogenous dopamine levels are increased by blocking dopamine reuptake and metabolism. We provide evidence in support of dedicated spinal network components that are controlled by excitatory D1 and inhibitory D2 receptors that is reminiscent of the classic dopaminergic indirect and direct pathway within the striatum. These results indicate that network state is an important factor that dictates receptor-specific and therefore dose-dependent control of neuromodulators on spinal network output and advances our understanding of how neuromodulators regulate neural networks under dynamically changing excitability.

Crosstalk between SHH and FGFR Signaling Pathways Controls Tissue Invasion in Medulloblastoma

In the Sonic Hedgehog (SHH) subgroup of medulloblastoma (MB), tumor initiation and progression are in part driven by smoothened (SMO) and fibroblast growth factor (FGF)-receptor (FGFR) signaling, respectively. We investigated the impact of the SMO-FGFR crosstalk on tumor growth and invasiveness in MB. We found that FGFR signaling represses GLI1 expression downstream of activated SMO in the SHH MB line DAOY and induces MKI67, HES1, and BMI1 in DAOY and in the group 3 MB line HD-MBO3. FGFR repression of GLI1 does not affect proliferation or viability, whereas inhibition of FGFR is necessary to release SMO-driven invasiveness. Conversely, SMO activation represses FGFR-driven sustained activation of nuclear ERK. Parallel activation of FGFR and SMO in ex vivo tumor cell-cerebellum slice co-cultures reduced invasion of tumor cells without affecting proliferation. In contrast, treatment of the cells with the SMO antagonist Sonidegib (LDE225) blocked invasion and proliferation in cerebellar slices. Thus, sustained, low-level SMO activation is necessary for proliferation and tissue invasion, whereas acute, pronounced activation of SMO can repress FGFR-driven invasiveness. This suggests that the tumor cell response is dependent on the relative local abundance of the two factors and indicates a paradigm of microenvironmental control of invasion in SHH MB through mutual control of SHH and FGFR signaling.