SALM4 suppresses excitatory synapse development by cis-inhibiting trans-synaptic SALM3-LAR adhesion

Synaptic adhesion molecules regulate various aspects of synapse development, function and plasticity. These functions mainly involve trans-synaptic interactions and positive regulations, whereas cis-interactions and negative regulation are less understood. Here we report that SALM4, a member of the SALM/Lrfn family of synaptic adhesion molecules, suppresses excitatory synapse development through cis inhibition of SALM3, another SALM family protein with synaptogenic activity. Salm4-mutant (Salm4) mice show increased excitatory synapse numbers in the hippocampus. SALM4 cis-interacts with SALM3, inhibits trans-synaptic SALM3 interaction with presynaptic LAR family receptor tyrosine phosphatases and suppresses SALM3-dependent presynaptic differentiation. Importantly, deletion of Salm3 in Salm4 mice (Salm3, Salm4) normalizes the increased excitatory synapse number. These results suggest that SALM4 negatively regulates excitatory synapses via cis inhibition of the trans-synaptic SALM3-LAR adhesion. © The Author(s) 2016110101sciescopu

Calsyntenin-3 Interacts With Both α- And β-Neurexins in the Regulation of Excitatory Synaptic Innervation in Specific Schaffer Collateral Pathways

Calsyntenin-3 (Clstn3) is a postsynaptic adhesion molecule that induces presynaptic differentiation via presynaptic neurexins (Nrxns), but whether Nrxns directly bind to Clstn3 has been a matter of debate. Here, using LC-MS/MS-based protein analysis, confocal microscopy, RNAscope assays, and electrophysiological recordings, we show that β-Nrxns directly interact via their LNS domain with Clstn3 and Clstn3 cadherin domains. Expression of splice site 4 (SS4) insert-positive β-Nrxn variants, but not insert-negative variants, reversed the impaired Clstn3 synaptogenic activity observed in Nrxn-deficient neurons. Consistently, Clstn3 selectively formed complexes with SS4-positive Nrxns in vivo Neuron-specific Clstn3 deletion caused significant reductions in number of excitatory synaptic inputs. Moreover, expression of Clstn3 cadherin domains in CA1 neurons of Clstn3 conditional knockout mice rescued structural deficits in excitatory synapses, especially within the stratum radiatum layer. Collectively, our results suggest that Clstn3 links to SS4-positive Nrxns to induce presynaptic differentiation and orchestrate excitatory synapse development in specific hippocampal neural circuits, including Schaffer collateral afferents. © 2020 Kim et al.1

LRRTM3 Regulates Excitatory Synapse Development through Alternative Splicing and Neurexin Binding

The four members of the LRRTM family (LRRTM1-4) are postsynaptic adhesion molecules essential for excitatory synapse development. They have also been implicated in neuropsychiatric diseases. Here, we focus on LRRTM3, showing that two distinct LRRTM3 variants generated by alternative splicing regulate LRRTM3 interaction with PSD-95, but not its excitatory synapse-promoting activity. Overexpression of either LRRTM3 variant increased excitatory synapse density in dentate gyrus (DG) granule neurons, whereas LRRTM3 knockdown decreased it. LRRTM3 also controlled activity-regulated AMPA receptor surface expression in an alternative splicing-dependent manner. Furthermore, Lrrtm3-knockout mice displayed specific alterations in excitatory synapse density, excitatory synaptic transmission and excitability in DG granule neurons but not in CA1 pyramidal neurons. Lastly, LRRTM3 required only specific splice variants of presynaptic neurexins for their synaptogenic activity. Collectively, our data highlight alternative splicing and differential presynaptic ligand utilization in the regulation of LRRTMs, revealing key regulatory mechanisms for excitatory synapse development.Peer reviewe

Understanding and Controlling Nanoscale Morphology in Self-Assembled Semiconducting Materials

Self-assembled semiconducting materials have been rapidly developed for a range of applications. This work aims to control the morphology of nanostructured semiconductors to understand how their functions arise from the structural properties. The first part of this dissertation focuses on the formation of a bulk-heterojunction (BHJ) in the active layer of organic photovoltaics (OPV). A BHJ is a bicontinuous interpenetrating network of organic components. The phase separation of the electron donor and the acceptor is required to achieve a BHJ structure in the nanostructured morphology, which promotes an efficient charge transportation. The use of solvent additive is one of the strategies to control the spontaneous phase separation during the film formation. Low vapor pressure solvent additives are introduced to a polymer casting solution in a sequentially processed OPV system, to study the swelling effect on the phase separation. In particular, the change in crystallinity and vertical mixing will be intensively studied upon polymer swelling. As another strategy, we introduce a molecular structure change to fullerene derivatives. A small structural variation leads to a large enough contrast of their surface energy, which is attributed to different vertical phase separation in the active layer. It eventually allows us to examine photovoltaic performance and device physics.In the second part, mesoporous inorganic films are investigated by preparation from a nanocrystal solution or sol-gel precursors for solar energy applications. Mesoporous nanocrystal-based titania is synthesized for inorganic/organic hybrid solar cells. The effect of surface modification is examined by anchoring a fullerene derivative on to titania surface. 3D interconnected mesoporous tantalum nitride films are prepared via sol-gel method as photoanodes in solar water splitting. The simple synthetic method using polymer template enables us to successfully prepare nitride films with excellent pore periodicity. The porous tantalum nitride film is examined with photoelectrochemical measurement to investigate the correlation between nanostructuring and photocatalytic activity. For the final part of this dissertation, porous cobalt ferrite and cadmium sulfide films are studied using ellipsometric porosimetry. Understanding the nature of their pores allows us to tune the intrinsic properties of the materials or prove the newly designed synthetic method

A Study on the Network Effectiveness of Sustainable K-Fashion and Beauty Creator Media (Social Media) in the Digital Era

With the convergence of various media in the digital era, the influence of Korean fashion/beauty on popular culture is growing rapidly. This study examines the sustainable relationship between the content and community characteristics of Korean fashion/beauty creator media, the associated social exchange relationships, and the effectiveness of the network among international consumers. In total, 614 international consumers who had made Korean fashion product purchases, viewed Korean fashion creator media, and shared information related to Korean fashion at least once were selected as a sample. Frequency analysis, reliability and validity analysis, measurement model analysis, and path analysis were conducted using SPSS and AMOS. The results showed that, first, content uniqueness had a significant effect on perceived similarity, although content continuity did not. In addition, content uniqueness and content continuity both had a significant effect on emotional expectations. Second, community scalability and community cohesion both had a significant effect on perceived similarity, and community scalability and community cohesion had a significant effect on emotional expectations. Third, perceived similarity had a significant effect on both emotional expectation consciousness and parasocial interaction, and emotional expectation consciousness had a significant effect on parasocial interaction. Finally, parasocial interaction had a significant effect on fad-like behavior. Through this, this study expanded the scope of academic research by linking the contents and community characteristics of Korean fashion/beauty creator media with research problems in the field of social exchange from the perspective of network effectiveness. Integrating this with the existing studies on consumer acceptance of Hallyu culture is expected to lead to the development of a more descriptive theoretical model for the formation of attitudes and purchase intentions toward Korean fashion/beauty products

Glycosylation and behavioral symptoms in neurological disorders

Glycosylation, the addition of glycans or carbohydrates to proteins, lipids, or other glycans, is a complex post-translational modification that plays a crucial role in cellular function. It is estimated that at least half of all mammalian proteins undergo glycosylation, underscoring its importance in the functioning of cells. This is reflected in the fact that a significant portion of the human genome, around 2%, is devoted to encoding enzymes involved in glycosylation. Changes in glycosylation have been linked to various neurological disorders, including Alzheimer’s disease, Parkinson’s disease, autism spectrum disorder, and schizophrenia. Despite its widespread occurrence, the role of glycosylation in the central nervous system remains largely unknown, particularly with regard to its impact on behavioral abnormalities in brain diseases. This review focuses on examining the role of three types of glycosylation: N-glycosylation, O-glycosylation, and O-GlcNAcylation, in the manifestation of behavioral and neurological symptoms in neurodevelopmental, neurodegenerative, and neuropsychiatric disorders. © 2023, The Author(s).11Nsciescopu

The Health Status of Informal Waste Collectors in Korea

Background: A broad, holistic approach was performed among informal waste collectors (IWCs) in Korea to understand their complex multidimensional health and safety problems. Methods: In the quantitative study, a survey of IWCs was conducted at four junk shops in Gangbuk-gu, Seoul, and survey data were used to calculate age-standardized prevalence rates based on comparisons with the general population in Korea. A qualitative study was also performed to provide more details on IWCs’ occupational and musculoskeletal injuries and depression. Results: In the quantitative study, the age-standardized prevalence rate (aSPR) of occupational injury was higher than that of the general standard population (aSPR: 10.42, 95% confidence interval (CI) 5.19–18.64) and that of blue-collar workers (aSPR: 4.65, 95% CI 2.32–8.32). Regarding musculoskeletal problems, compared to employed populations, the aSPRs of shoulder pain (aSPR: 2.63, 95% CI 1.60–4.06), wrist pain (aSPR: 3.33, 95% CI 1.33–6.86), knee pain (aSPR: 1.51, 95% CI 1.01–2.17), and ankle pain (aSPR: 3.54, 95% CI 1.14–8.26) were higher. Regarding psychological problems, depression (aSPR: 2.55, 95% CI 1.27–4.56) and suicidal or self-harm ideation (aSPR: 2.09, 95% CI 1.11–3.58) were higher compared to general populations. Through the qualitative study and case study on muscular problems, more details on the work environment problems of IWCs were obtained. Conclusions: IWCs are exposed to various occupational hazards and lack proper protection. They show a high prevalence of occupational injury, musculoskeletal disease, and depression

A quantitative analysis of spontaneous alternation behaviors on a Y-maze reveals adverse effects of acute social isolation on spatial working memory

Abstract Animals tend to alternate between different choices, which requires the ability to remember recent choices. The Y-maze spontaneous alternation test is widely used in various animal models for assessing short-term memory, and its precise evaluation depends upon the accurate determination of the arm visit sequence. However, an objective method for defining arm visits is lacking owing to uncertainty regarding the extent to which an animal must go into the arm to be considered visited. Here, we conducted quantitative analyses on mice behavior in the Y-maze while systematically varying the arm visit threshold and assessed the effect of acute social isolation on spatial working memory. Our results revealed that 24-h social isolation significantly reduced spontaneous alternation rate when the arm threshold was set at the distal part of the arm. Furthermore, the memory of the recently visited arms faded away faster in the socially isolated mice. However, other behavioral factors were comparable to those of the group-housed mice, indicating a specific impairment of short-term memory. Our findings suggest that the location of arm visit threshold is critical for the precise evaluation of short-term memory, and our study provides a method for comprehensively and systematically assessing spontaneous alternation behavior in the Y-maze

A Room-Temperature, Solution Phase Method for the Synthesis of Mesoporous Metal Chalcogenide Nanocrystal-Based Thin Films with Precisely Controlled Grain Sizes

Block copolymer templating of ligand-stripped nanocrystals followed by thermal degradation of the polymer template is a robust method that has been applied in making a variety of mesoporous nanocrystal-based films. However, the use of thermal processing to remove the polymer template can have detrimental effects on other material properties such as grain size and crystal structure that affect size-dependent properties such as the band gap. Here we present a new method for forming mesoporous films of cadmium and lead chalcogenide nanocrystals that avoids thermal processing. In our method, nanocrystals are first assembled with a diblock copolymer template. The resulting films are then soaked in a solution of a small molecule cross-linking agent to lock the nanocrystals into the structure. Finally, the polymer template is gently dissolved out of the film, leaving behind a porous film of nanocrystals. These films show disordered but homogeneous porosity, quantified by electron microscopy and ellipsometric porosimetry. Importantly, both X-ray diffraction and optical absorption spectroscopy indicate that the initial nanocrystal size is fully preserved in the final porous structure. This new synthetic method has exciting potential as a building block for composite structures where precise control of quantum confinement effects is needed