Arhgef16, a novel Elmo1 binding partner, promotes clearance of apoptotic cells via RhoG-dependent Rac1 activation

AbstractElmo is an evolutionarily conserved mammalian ortholog of Caenorhabditis elegans CED-12 with proposed roles during the removal of apoptotic cells, cell migration, neurite outgrowth, and myoblast fusion (Katoh and Negishi (2003) [1], Park and Tosello (2007) [2], Grimsley et al. (2004) [3], Hamoud et al. (2014) [4]). Elmo mediates these cellular processes by interacting with various proteins located in the plasma membrane, cytoplasm and nucleus, and by modulating their activities although it has no intrinsic catalytic activity (Park and Tosello (2007) [2], Hamoud et al. (2014) [4], Li et al. (2013) [5], Margaron, Fradet and Cote (2013) [6], and Mauldin et al. (2013)[7]). Because there are a limited number of proteins known to interact with Elmo, we performed a yeast two-hybrid screen using Elmo1 as bait to identify Elmo1-interacting proteins and to evaluate their mode of regulation. Arhgef16 was one of the proteins identified through the screen and subsequent analyses revealed that Arhgef16 interacted with Elmo1 in mammalian cells as well. Expression of Arhgef16 in phagocytes promoted engulfment of apoptotic cells, and engulfment mediated by Arhgef16 increased synergistically in the presence of Elmo1 but was abrogated in the absence of Elmo1. In addition, Arhgef16-mediated removal of apoptotic cells was dependent on RhoG, but independent of Dock1. Taken together, this study suggests that the newly identified Elmo1-interacting protein, Arhgef16, functions synergistically with Elmo1 to promote clearance of apoptotic cells in a RhoG-dependent and Dock1-independent manner

m6A mRNA demethylase FTO regulates melanoma tumorigenicity and response to anti-PD-1 blockade

Melanoma is one of the most deadly and therapy-resistant cancers. Here we show that N6-methyladenosine (m6A) mRNA demethylation by fat mass and obesity-associated protein (FTO) increases melanoma growth and decreases response to anti-PD-1 blockade immunotherapy. FTO level is increased in human melanoma and enhances melanoma tumorigenesis in mice. FTO is induced by metabolic starvation stress through the autophagy and NF-κB pathway. Knockdown of FTO increases m6A methylation in the critical protumorigenic melanoma cell-intrinsic genes including PD-1 (PDCD1), CXCR4, and SOX10, leading to increased RNA decay through the m6A reader YTHDF2. Knockdown of FTO sensitizes melanoma cells to interferon gamma (IFNγ) and sensitizes melanoma to anti-PD-1 treatment in mice, depending on adaptive immunity. Our findings demonstrate a crucial role of FTO as an m6A demethylase in promoting melanoma tumorigenesis and anti-PD-1 resistance, and suggest that the combination of FTO inhibition with anti-PD-1 blockade may reduce the resistance to immunotherapy in melanoma. © 2019, The Author(s)

CVD-grown monolayer MoS2 in bioabsorbable electronics and biosensors

Transient electronics entails the capability of electronic components to dissolve or reabsorb in a controlled manner when used in biomedical implants. Here, the authors perform a systematic study of the processes of hydrolysis, bioabsorption, cytotoxicity and immunological biocompatibility of monolayer MoS2

Regeneration of a full-thickness defect of rotator cuff tendon with freshly thawed umbilical cord-derived mesenchymal stem cells in a rat model

Background It is difficult to immediately use mesenchymal stem cells (MSCs) for the patient with rotator cuff disease because isolation and culture time are required. Thus, the MSCs would be prepared in advanced in cryopreserved condition for an off-the-shelf usage in clinic. This study investigated the efficacy of freshly thawed MSCs on the regeneration of a full-thickness tendon defect (FTD) of rotator cuff tendon in a rat model. Methods We evaluated morphology, viability, and proliferation of cultured umbilical cord-derived MSCs (C-UC MSCs) and freshly thawed umbilical cord-derived MSCs (T-UC MSCs) at passage 10 in vitro. In animal experiments, we created a FTD in the supraspinatus of rats and injected the injured tendon with saline, cryopreserved agent (CPA; control), C-UC MSCs, and T-UC MSCs, respectively. Two and 4 weeks later, macroscopic, histological, biomechanical, and cell trafficking were evaluated. T test and ANOVA were used with SPSS. Differences with p < .05 were considered statistically significant. Results T-UC MSCs had fibroblast-like morphology and showed greater than 97% viability and stable proliferation comparable to the C-UC MSCs at passage 10. In animal experiments, compared with the control group, the macroscopic appearance of the T-UC MSCs was more recovered at 2 and 4 weeks such as inflammation, defect size, neighboring tendon, swelling/redness, the connecting surrounding tissue and slidability. Histologically, the nuclear aspect ratio, orientation angle of fibroblasts, collagen organization, and fiber coherence were improved by 33.33%, 42.75%, 1.86-fold, and 1.99-fold at 4 weeks, and GAG-rich area decreased by 88.13% and 94.70% at 2 and 4 weeks respectively. Further, the T-UC MSCs showed enhanced ultimate failure load by 1.55- and 1.25-fold compared with the control group at both 2 and 4 weeks. All the improved values of T-UC MSCs were comparable to those of C-UC MSCs. Moreover, T-UC MSCs remained 8.77% at 4 weeks after injury, and there was no significant difference between C-UC MSCs and T-UC MSCs. Conclusions The morphology, viability, and proliferation of T-UC MSCs were comparable to those of C-UC MSCs. Treatment with T-UC MSCs could induce tendon regeneration of FTD at the macroscopic, histological, and biomechanical levels comparable to treatment with C-UC MSCs.This study was supported by a grant (NRF-2015M3A9E6028412) of the Bio & Medical Technology Development Program and a grant (NRF2017R1A2B2010995) awarded by the Basic Science Research Program of the National Research Foundation of Korea

CD160 serves as a negative regulator of NKT cells in acute hepatic injury

[EN] CD160 and BTLA both bind to herpes virus entry mediator. Although a negative regulatory function of BTLA in natural killer T (NKT) cell activation has been reported, whether CD160 is also involved is unclear. By analyzing CD160−/− mice and mixed bone marrow chimeras, we show that CD160 is not essential for NKT cell development. However, CD160−/− mice exhibit severe liver injury after in vivo challenge with α-galactosylceramide (α-GalCer). Moreover, CD160−/− mice are more susceptible to Concanavalin A challenge, and display elevated serum AST and ALT levels, hyperactivation of NKT cells, and enhanced IFN-γ, TNF, and IL-4 production. Lastly, inhibition of BTLA by anti-BTLA mAb aggravates α-GalCer-induced hepatic injury in CD160−/− mice, suggesting that both CD160 and BTLA serve as non-overlapping negative regulators of NKT cells. Our data thus implicate CD160 as a co-inhibitory receptor that delivers antigen-dependent signals in NKT cells to dampen cytokine production during early innate immune activationSIWe thank the NIH Tetramer Core Facility for providing PBS 57 ligand loaded CD1d Tetramers. Further, we thank the staffs of Gyerim Experimental Animal Resource Center for animal care and technical assistance. K.-M. Lee was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT, and Future planning (NRF-2016M3A9B6948342, NRF- 2017R1A2B3004828, and NRF-2018M3A9D3079288). S.-J. Kim was supported by the Korea Health Industry Development Institute (KHIDI-HI14C2640) grant funded by Korea Government. S.-J. Ha was supported by a grant from the NRF (NRF- 2018R1A2A1A05076997). T.-J. Kim was additionally supported by a grant from the NRF (NRF-2016R1A6A3A04009698

Prospective analysis of video head impulse tests in patients with acute posterior circulation stroke

BackgroundVideo head impulse tests (vHITs), assessing the vestibulo-ocular reflex (VOR), may be helpful in the differential diagnosis of acute dizziness. We aimed to investigate vHITs in patients with acute posterior circulation stroke (PCS) to examine whether these findings could exhibit significant abnormalities based on lesion locations, and to evaluate diagnostic value of vHIT in differentiating dizziness between PCS and vestibular neuritis (VN).MethodsWe prospectively recruited consecutive 80 patients with acute PCS and analyzed vHIT findings according to the presence of dorsal brainstem stroke (DBS). We also compared vHIT findings between PCS patients with dizziness and a previously studied VN group (n = 29). Receiver operating characteristic (ROC) analysis was performed to assess the performance of VOR gain and its asymmetry in distinguishing dizziness between PCS and VN.ResultsPatients with PCS underwent vHIT within a median of 2 days from stroke onset. Mean horizontal VOR gain was 0.97, and there was no significant difference between PCS patients with DBS (n = 15) and without (n = 65). None exhibited pathologic overt corrective saccades. When comparing the PCS group with dizziness (n = 40) to the VN group (n = 29), patients with VN demonstrated significantly lower mean VOR gains in the ipsilesional horizontal canals (1.00 vs. 0.57, p &lt; 0.001). VOR gain and their asymmetry effectively differentiated dizziness in the PCS from VN groups, with an area under the ROC curve of 0.86 (95% CI 0.74–0.98) and 0.91 (95% CI 0.83–0.99, p &lt; 0.001), respectively.ConclusionSignificantly abnormal vHIT results were rare in patients with acute PCS, even in the presence of DBS. Moreover, vHIT effectively differentiated dizziness between PCS and VN, highlighting its potential for aiding differential diagnosis of acute dizziness

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

Applying cultural evolutionary theory to the technological transition during the Late Pleistocene in Korea

Thesis (Ph.D.)--University of Washington, 2023The cultural-technological transition in stone artifacts from the Middle to Upper Paleolithic during the Late Pleistocene is considered as one of the major revolutions in the prehistory of humankind, along with the appearance of modern humans. The new technologies include introduction of blade and bladelets, a high degree of morphological standardization in tool types, exploitation of bone, antler, and ivory as raw materials for tools, systematic use of grinding and pounding stone tools, and extensive use of bows and arrows. One of the explanations for this transition is to connect the technological change to hunter-gatherers’ subsistence strategies using a theoretical framework derived from cultural evolution theory. The evolutionary approach enables us to understand human behaviors by linking material evidence and socio-environmental dynamics. In this research, I explore the technological transition from the Early to Late Paleolithic in Korea represented by the appearance of stemmed points through evolutionary concepts including human behavioral ecology (HBE) and cultural transmission (CT). I also examined different likely uses of stemmed points by measuring tip cross-sectional area (TCSA). The previous studies have primarily discussed the origin and route of stemmed points and blades while my research focuses more on related human behaviors and decision-making processes. I raised three questions to address cultural and environmental roles in the technological transition: what changes in foragers’ landscape use and mobility were associated with the introduction of new tools? What were stemmed points used for? And what was the dominant mode of cultural transmission during the time of technological innovation in the Korean Late Paleolithic? My approach to answer these questions is combined with traditional theoretical frameworks and novel methods for testing hypotheses. As an answer to the first question, I hypothesized that stemmed points enabled foragers to survive in more marginal and extreme environments based on HBE. I applied quantitative analyses of artifact volumetric density, retouch frequency, composition of toolkits, and artifact raw materials. I explore environmental and demographic contexts by applying paleoclimate simulations and summed probability distribution models. My results show that forager groups using stemmed points may have been associated with occupation of marginal or extreme environments, represented by higher altitude and decreased temperature. I raised the second question to understand the possible role of stemmed points played related during the technological transition. Using the metric called tip cross-sectional area (TCSA), I was able to discriminate between different likely use classes of projectile points such as stabbing spears or poisoned arrow tips. I also explored the temporal and spatial patterns of TCSA values of stemmed points. My results show the multiple likely uses of stemmed points in a site, which indicate people might use them as multi-functional tools, with many likely designed for javelin and stabbing spear tips. I applied the CT framework to examine the process and social context of the technological transition and address the third question. I built two models that describe the transition process based on guided variation and indirect bias and tested them through computing coefficients of variation (CV), and correlation coefficients. The results show high variation and low correlation between morphological attributes on stemmed points, indicating the guided variation as the dominant mode of cultural transmission. Combining all results, my dissertation research concludes that stemmed points were introduced to maximize the landscape use during the Late Pleistocene and the shape and usage of the tools were adjusted depending on the local environment. In addition to achieving research goals, this dissertation demonstrates how to apply theoretical frameworks and test hypotheses by applying noble quantitative methodologies. My research pursues an open science approach by enabling maximum access to research data, analysis processes, and final results to promote research transparency to promote reproducibility. I expect to see that my approaches will be adopted in future research about technological transition and cultural evolution

Cultural Transmission and the Social Contexts of Technological Transitions during the Late Paleolithic of Korea

The onset of the Late Paleolithic period in Korea, represented by the appearance of stemmed points and blades, was a key event in the dispersal of modern humans in Northeast Asia. Previous studies have mainly focused on possible origin locations of these new technologies. The specific cultural processes of the appearance of stemmed points and blades have rarely been considered. We explore these cultural processes by applying a cultural transmission framework to investigate the social contexts of the emergence of these new technologies. Our main question is: what was the dominant mode of cultural transmission during this time of technological innovation in the Korean Late Paleolithic? Following Bettinger and Eerkens (1999), we evaluated models of guided variation and indirect bias using data from Korean assemblages containing stemmed points. To evaluate these models and understand the transmission processes, we computed correlation coefficients and coefficients of variation (CV). We found that information about the new technology was likely transmitted via guided variation with small contribution from indirect bias. Some attributes, including length and width, were transmitted with less variation while other attributes have more variation. Our results suggest that the dominant mode of cultural transmission for the earliest stemmed points was guided variation. A slight shift in the social context of transmission towards indirect bias was observed in the later chronological phase. We assume that individuals or groups developed stemmed points by experimenting with existing blade technologies and then copied crucial parts of a successful model to ensure the quality to optimize tool usage. As a result, the shape of stemmed points became more standardized among their social groups