The role and regulation of Frizzled receptors in synapse formation

The formation of synapses is crucial for brain function. Secreted Wnt proteins signal through Frizzled and other receptors to regulate synaptogenesis. In particular, Wnt7a promotes synaptogenesis in the hippocampus. The receptor Fz5 mediates Wnt7a-induced presynaptic assembly, but the mechanisms underlying Fz5 regulation are not well understood. How Wnt7a signals at postsynaptic sites is also unknown. Fz7, another receptor binding Wnt7a, is hypothesised to have a role in this process. To address these questions, I used biochemical and cell biology techniques combining in vitro and in vivo approaches. My findings demonstrate that Fz5 and Fz7 have distinct synaptic localisation. Fz5 is absent from dendritic spines - excitatory postsynaptic structures - and is not required for spine development. In contrast, Fz7 localises in spines and is required for Wnt7a-induced spine formation. Our preliminary data suggested that Fz5 is palmitoylated, a post-translational lipid modification that affects protein distribution and function. I demonstrated that all Frizzled receptors can be palmitoylated. Using a palmitoylation-deficient Fz5 receptor, I showed that palmitoylation is required for Fz5 interaction with the scaffold protein Dishevelled, a key component of the Wnt signalosome, but has no impact on Fz5 degradation rate and lateral mobility at the plasma membrane. Palmitoylation-deficient Fz5 exhibits impaired axonal distribution, increased endocytosis and decreased surface levels. Expression of wild-type Fz5 in the hippocampus promotes presynaptic assembly, whereas palmitoylation-deficient Fz5 lacks synaptogenic activity. Palmitoylation is therefore a critical molecular mechanism that underpins Fz5 regulation and function in vivo. These findings demonstrate that two distinct Frizzled receptors act pre- and postsynaptically to promote synaptogenesis, and reveal a previously uncharacterised lipid modification of Frizzled receptors, which is of critical functional importance. This work opens up new avenues to study the role of Frizzled palmitoylation in different biological contexts, from cell fate decisions to neuronal circuit formation and plasticity

MIDDLE MIOCENE OSTRACODS FROM THE SALENTINE PENINSULA

The ostracod faunas of the S. Caterina and S. Maria al Bagno sections (Salentine Peninsula, Apulia) were studied. These sections comprise the lower and middle levels of the Pietra Leccese formationand range collectively from the uppermost Burdigalian or the lower Langhian to the middle Serravallian. Forty-one species, belonging to twenty-seven genera were identified. Nineteen species known previously are illustrated and discussed; six (Carinocythereis messapica n. sp., Celtia multicostata n. sp., Cytherella obesa n. sp., Cytherella polygonalis n. sp., Cytherella salentinensis n. sp. and Cytherelloidea ? rectangularisn. sp.) are described as new, and two are left in open nomenclature. The stratigraphic distribution of a remarkable number ofshelf ostracod species,known previously from the Upper Miocene upwards, includes also part of the Middle Miocene.&nbsp

ALLOSTRATIGRAPHY AND SEISMIC STRATIGRAPHY OF THE MIOCENE SEDIMENTS OF THE SPICCHIAIOLA - POMARANCE AREA, SOUTHERN SIDE OF THE VOLTERRA BASIN (TUSCANY, ITALY)

The objective of this work is to analyze the Miocene depositional units of the southern side of the Volterra Basin (Tuscany, Italy) utilizing outcrop and seismic data and to establish the major events that led to their formation. Four depositional units have been recognized: Unit 1 is characterized by marine sediments of late Serravallian-early Tortonian age; Unit 2 is characterized by fluvio-lacustrine and brackish deposits of late Tortonian-early Messinian age; Unit 3 is characterized by marine deposits of early Messinian age; Unit 4 is characterized by the lacustrine deposits ("Lago-mare" facies) of late Messinian age. The deposition of these four units is associated with an extensional tectonic regime that has been active in Tuscany since the late Tortonian. This regime generated half graben type structures in which deposition occurred. The recognized unconformities between the units are mainly related to uplift as a consequence of the extensional tectonic regime.   &nbsp

NOTE GEOLOGICHE E STRATIGRAFICHE SULL'AREA DI PALMARIGGI (LECCE, PUGLIA)

The geological mapping and the biostratigraphic study of Neogene sediments outcropping near Palmariggi, a small area between Otranto and Maglie (Puglia), have been carried out. Above the dolomitic limestone units of the Cretaceous-Oligocene platform three sedimentary cycles have been recognized, one of Miocene and two of Pliocene age. The first cycle consists of two units: the Pietra leccese and the overlying Calcareniti di Andrano; the second cycle is represented by the Lèuca Formation and the last cycle by the Uggiano la Chiesa Formation. The pre-Neogene units are affected by a folding episode with major structures trending NNW- SSE. A subsequent tectonic event characterized by folds with axial directions interferring with the previous one has been detected in the pre-Neogene units. The latter deformation affects also the Miocene successions. Both the previous deformative episodes control the outcrop distribution of the Neogene sediments, preserved in the low structural sites such as synclinal cores. In the Palmariggi area an extensional tectonics of pre-Pliocene age follows the folding related to the compressive episodes. The normal faults linked to this late extension, show a NNW-SSE trend

S-acylation of the Wnt receptor Frizzled-5 by zDHHC5 controls its cellular localization and synaptogenic activity in the rodent hippocampus

Proper localization of receptors for synaptic organizing factors is crucial for synapse formation. Wnt proteins promote synapse assembly through Frizzled (Fz) receptors. In hippocampal neurons, the surface and synaptic localization of Fz5 is regulated by neuronal activity, but the mechanisms involved remain poorly understood. Here, we report that all Fz receptors can be post-translationally modified by S-acylation and that Fz5 is S-acylated on three C-terminal cysteines by zDHHC5. S-acylation is essential for Fz5 localization to the cell surface, axons, and presynaptic sites. Notably, S-acylation-deficient Fz5 is internalized faster, affecting its association with signalosome components at the cell surface. S-acylation-deficient Fz5 also fails to activate canonical and divergent canonical Wnt pathways. Fz5 S-acylation levels are regulated by the pattern of neuronal activity. In vivo studies demonstrate that S-acylation-deficient Fz5 expression fails to induce presynaptic assembly. Our studies show that S-acylation of Frizzled receptors is a mechanism controlling their localization and function

Characterization of the structure and control of the blood-nerve barrier identifies avenues for therapeutic delivery

The blood barriers of the nervous system protect neural environments but can hinder therapeutic accessibility. The blood-brain barrier (BBB) is well characterized, consisting of endothelial cells with specialized tight junctions and low levels of transcytosis, properties conferred by contacting pericytes and astrocytes. In contrast, the blood-nerve barrier (BNB) of the peripheral nervous system is poorly defined. Here, we characterize the structure of the mammalian BNB, identify the processes that confer barrier function, and demonstrate how the barrier can be opened in response to injury. The homeostatic BNB is leakier than the BBB, which we show is due to higher levels of transcytosis. However, the barrier is reinforced by macrophages that specifically engulf leaked materials, identifying a role for resident macrophages as an important component of the BNB. Finally, we demonstrate the exploitation of these processes to effectively deliver RNA-targeting therapeutics to peripheral nerves, indicating new treatment approaches for nervous system pathologies

Microenvironmental regulation of the IL-23R/IL-23 axis overrides chronic lymphocytic leukemia indolence

Although the progression of chronic lymphocytic leukemia (CLL) requires the cooperation of the microenvironment, the exact cellular and molecular mechanisms involved are still unclear. We investigated the interleukin (IL)-23 receptor (IL-23R)/IL-23 axis and found that circulating cells from early-stage CLL patients with shorter time-to-treatment, but not of those with a more benign course, expressed a defective form of the IL-23R complex lacking the IL-12R beta 1 chain. However, cells from both patient groups expressed the complete IL-23R complex in tissue infiltrates and could be induced to express the IL-12R. 1 chain when cocultured with activated T cells or CD40L(+) cells. CLL cells activated in vitro in this context produced IL-23, a finding that, together with the presence of IL-23 in CLL lymphoid tissues, suggests the existence of an autocrine/paracrine loop inducing CLL cell proliferation. Interference with the IL-23R/IL-23 axis using an anti-IL-23p19 antibody proved effective in controlling disease onset and expansion in xenografted mice, suggesting potential therapeutic strategies

Modeling of GERDA Phase II data

The GERmanium Detector Array (GERDA) experiment at the Gran Sasso underground laboratory (LNGS) of INFN is searching for neutrinoless double-beta ($0\nu\beta\beta$) decay of $^{76}$Ge. The technological challenge of GERDA is to operate in a "background-free" regime in the region of interest (ROI) after analysis cuts for the full 100$\,$kg$\cdot$yr target exposure of the experiment. A careful modeling and decomposition of the full-range energy spectrum is essential to predict the shape and composition of events in the ROI around $Q_{\beta\beta}$ for the $0\nu\beta\beta$ search, to extract a precise measurement of the half-life of the double-beta decay mode with neutrinos ($2\nu\beta\beta$) and in order to identify the location of residual impurities. The latter will permit future experiments to build strategies in order to further lower the background and achieve even better sensitivities. In this article the background decomposition prior to analysis cuts is presented for GERDA Phase II. The background model fit yields a flat spectrum in the ROI with a background index (BI) of $16.04^{+0.78}_{-0.85} \cdot 10^{-3}\,$cts/(kg$\cdot$keV$\cdot$yr) for the enriched BEGe data set and $14.68^{+0.47}_{-0.52} \cdot 10^{-3}\,$cts/(kg$\cdot$keV$\cdot$yr) for the enriched coaxial data set. These values are similar to the one of Gerda Phase I despite a much larger number of detectors and hence radioactive hardware components

Modeling of GERDA Phase II data

The GERmanium Detector Array (Gerda) experiment at the Gran Sasso underground laboratory (LNGS) of INFN is searching for neutrinoless double-beta (0νββ) decay of 76Ge. The technological challenge of Gerda is to operate in a “background-free” regime in the region of interest (ROI) after analysis cuts for the full 100 kg·yr target exposure of the experiment. A careful modeling and decomposition of the full-range energy spectrum is essential to predict the shape and composition of events in the ROI around Qββ for the 0νββ search, to extract a precise measurement of the half-life of the double-beta decay mode with neutrinos (2νββ) and in order to identify the location of residual impurities. The latter will permit future experiments to build strategies in order to further lower the background and achieve even better sensitivities. In this article the background decomposition prior to analysis cuts is presented for Gerda Phase II. The background model fit yields a flat spectrum in the ROI with a background index (BI) of 16.04+0.78−0.85⋅10−3 cts/(keV·kg·yr) for the enriched BEGe data set and 14.68+0.47−0.52⋅10−3 cts/(keV·kg·yr) for the enriched coaxial data set. These values are similar to the one of Phase I despite a much larger number of detectors and hence radioactive hardware components

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements