Thomas L. Kash, Kristen E. Pleil, Catherine A. Marcinkiewcz, Emily G. Lowery-Gionta, Nicole Crowley, Christopher Mazzone, Jonathan Sugam, J. Andrew Hardaway, and Zoe A. McElligottMol. Cells 2015; 38(1): 1-13 https://doi.org/10.14348/molcells.2015.2261
Abstract : Recent technical developments have transformed how neuroscientists can probe brain function. What was once thought to be difficult and perhaps impossible, stimulating a single set of long range inputs among many, is now relatively straight-forward using optogenetic approaches. This has provided an avalanche of data demonstrating causal roles for circuits in a variety of behaviors. However, despite the critical role that neuropeptide signaling plays in the regulation of behavior and physiology of the brain, there have been remarkably few studies demonstrating how peptide release is causally linked to behaviors. This is likely due to both the different time scale by which peptides act on and the modulatory nature of their actions. For example, while glutamate release can effectively transmit information between synapses in milliseconds, peptide release is potentially slower [See the excellent review by Van Den Pol on the time scales and mechanisms of release (
Inji Park, and Hyun-Shik LeeMol. Cells 2015; 38(1): 14-19 https://doi.org/10.14348/molcells.2015.2116
Abstract : Eph receptors and their ligands, ephrins, represent the largest group of the receptor tyrosine kinase (RTK) family, and they mediate numerous developmental processes in a variety of organisms. Ephrins are membrane-bound proteins that are mainly divided into two classes: A class ephrins, which are linked to the membrane by a glycosylphosphatidylinositol (GPI) linkage, and B class ephrins, which are transmembrane ligands. Based on their domain structures and affinities for ligand binding, the Eph receptors are also divided into two groups. Trans-dimerization of Eph receptors with their membrane-tethered ligands regulates cell-cell interactions and initiates bidirectional signaling pathways. These pathways are intimately involved in regulating cytoskeleton dynamics, cell migration, and alterations in cellular dynamics and shapes. The EphBs and ephrinBs are specifically localized and modified to promote higher-order clustering and initiate of bidirectional signaling. In this review, we present an in-depth overview of the structure, mechanisms, cell signaling, and functions of EphB/ephrinB in cell adhesion and migration.
Su-hyun Park, Eun-Ho Jung, Geun-Young Kim, Byung-Chul Kim, Jae Hyang Lim, and Chang-Hoon WooMol. Cells 2015; 38(1): 20-25 https://doi.org/10.14348/molcells.2015.2120
Abstract : TGF-β regulates pleiotropic cellular responses including cell growth, differentiation, migration, apoptosis, extracellular matrix production, and many other biological processes. Although non-Smad signaling pathways are being increasingly reported to play many roles in TGF-β-mediated biological processes, Smads, especially receptor-regulated Smads (R-Smads), still play a central mediatory role in TGF-β signaling for epithelial-mesenchymal transition. Thus, the biological activities of R-Smads are tightly regulated at multiple points. Inhibitory Smad (I-Smad also called Smad7) acts as a critical endogenous negative feedback regulator of Smad-signaling pathways by inhibiting R-Smad phosphorylation and by inducing activated type I TGF-β receptor degradation. Roles played by Smad7 in health and disease are being increasingly reported, but the molecular mechanisms that regulate Smad7 are not well understood. In this study, we show that E3 ubiquitin ligase Itch acts as a positive regulator of TGF-β signaling and of subsequent EMT-related gene expression. Interestingly, the Itch-mediated positive regulation of TGF-β signaling was found to be dependent on Smad7 ubiquitination and its subsequent degradation. Further study revealed Itch acts as an E3 ubiquitin ligase for Smad7 polyubiquitination, and thus, that Itch is an important regulator of Smad7 activity and a positive regulator of TGF-β signaling and of TGF-β-mediated biological processes. Accordingly, the study uncovers a novel regulatory mechanism whereby Smad7 is controlled by Itch.
Hyo-Ji Lee, Keun-Cheol Kim, Jeong A Han, Sun Shim Choi, and Yu-Jin JungMol. Cells 2015; 38(1): 26-32 https://doi.org/10.14348/molcells.2015.2136
Abstract : Toll-like receptors (TLR) 7 and 9 transduce a cellular signal through the MyD88-dependent pathway and induce the production of inflammatory mediators against microbial nucleotide components. The repeated stimulation of TLR4 leads to endotoxin tolerance, but the molecular mechanisms of tolerance induced through the costimulation of individual TLR has not yet been established, although endosomal TLRs share signaling pathways with TLR4. In the present study, mouse macrophages were simultaneously stimulated with the TLR7 agonist, gardiquimod (GDQ), and the TLR9 agonist, CpG ODN 1826, to examine the mechanism and effector functions of macrophage tolerance. Compared with individual stimulation, the costimulation of both TLRs reduced the secretion of TNF-α and IL-6 through the delayed activation of the NF-κB pathway; notably, IL-10 remained unchanged in costimulated macrophages. This tolerance reflected the early induction of suppressor of cytokine signaling-1 (SOCS-1), according to the detection of elevated TNF-α secretion and restored NF-κB signaling in response to the siRNA-mediated abrogation of SOCS-1 signaling. In addition, the restimulation of each TLRs using the same ligand significantly reduced the expression of both TLRs in endosomes. These findings revealed that the costimulation of TLR7 and TLR9 induced macrophage tolerance via SOCS-1, and the restimulation of each receptor or both TLR7 and TLR9 downregulated TLR expression through a negative feedback mechanisms that protects the host from excessive inflammatory responses. Moreover, the insufficient and impaired immune response in chronic viral infection might also reflect the repeated and simultaneous stimulation of those endosomal TLRs.
Ke Xu, A. Francis Stewart, and Andrew C.G. PorterMol. Cells 2015; 38(1): 33-39 https://doi.org/10.14348/molcells.2015.2163
Abstract : The correction of disease-causing mutations by single-strand oligonucleotide-templated DNA repair (ssOR) is an attractive approach to gene therapy, but major improvements in ssOR efficiency and consistency are needed. The mechanism of ssOR is poorly understood but may involve annealing of oligonucleotides to transiently exposed single-stranded regions in the target duplex. In bacteria and yeast it has been shown that ssOR is promoted by expression of Redβ, a single-strand DNA annealing protein from bacteriophage lambda. Here we show that Redβ expression is well tolerated in a human cell line where it consistently promotes ssOR. By use of short interfering RNA, we also show that ssOR is stimulated by the transient depletion of the endogenous DNA mismatch repair protein MSH2. Furthermore, we find that the effects of Redβ expression and MSH2 depletion on ssOR can be combined with a degree of cooperativity. These results suggest that oligonucleotide annealing and mismatch recognition are distinct but interdependent events in ssOR that can be usefully modulated in gene correction strategies.
Hyeong Cheol Park, Shinyoung Lee, Bokyung Park, Wonkyun Choi, Chanmin Kim, Sanghun Lee, Woo Sik Chung, Sang Yeol Lee, Jamal Sabir, Ray A. Bressan, Hans J. Bohnert, Tesfaye Mengiste, and Dae-Jin YunMol. Cells 2015; 38(1): 40-50 https://doi.org/10.14348/molcells.2015.2165
Abstract : In the interaction between plants and pathogens, carbon (C) resources provide energy and C skeletons to maintain, among many functions, the plant immune system. However, variations in C availability on pathogen associated molecular pattern (PAMP) triggered immunity (PTI) have not been systematically examined. Here, three types of starch mutants with enhanced susceptibility to
Juyeon Lee, Jaya Bandyopadhyay, Jin Il Lee, Injeong Cho, Daeho Park, and Jeong Hoon ChoMol. Cells 2015; 38(1): 51-57 https://doi.org/10.14348/molcells.2015.2202
Abstract : The
Cuong Thach Nguyen, Eun-Hye Kim, Truc Thanh Luong, Suhkneung Pyo, and Dong-Kwon RheeMol. Cells 2015; 38(1): 58-64 https://doi.org/10.14348/molcells.2015.2231
Abstract : Activating transcription factor-3 (ATF3) acts as a negative regulator of cytokine production during Gram-negative bacterial infection. A recent study reported that ATF3 provides protection from
Hae-Min Park, Yoon-Woo Kim, Kyoung-Jin Kim, Young June Kim, Yung-Hun Yang, Jang Mi Jin, Young Hwan Kim, Byung-Gee Kim, Hosup Shim, and Yun-Gon KimMol. Cells 2015; 38(1): 65-74 https://doi.org/10.14348/molcells.2015.2240
Abstract : Carbohydrate antigens expressed on pig cells are considered to be major barriers in pig-to-human xenotransplantation. Even after α1,3-galactosyltransferase gene knock-out (GalT-KO) pigs are generated, potential non-Gal antigens are still existed. However, to the best of our knowledge there is no extensive study analyzing N-glycans expressed on the GalT-KO pig tissues or cells. Here, we identified and quantified totally 47 N-glycans from wild-type (WT) and GalT-KO pig fibroblasts using mass spectrometry. First, our results confirmed the absence of galactose-alpha-1,3-galactose (α-Gal) residue in the GalT-KO pig cells. Interestingly, we showed that the level of overall fucosylated
Kabsun Kim, Jung Ha Kim, Inyoung Kim, Jongwon Lee, Semun Seong, Yong-Wook Park, and Nacksung KimMol. Cells 2015; 38(1): 75-80 https://doi.org/10.14348/molcells.2015.2241
Abstract : Osteoclasts are unique cells responsible for the resorption of bone matrix. MicroRNAs (miRNAs) are involved in the regulation of a wide range of physiological processes. Here, we examined the role of miR-26a in RANKL-induced osteoclastogenesis. The expression of miR-26a was up-regulated by RANKL at the late stage of osteoclastogenesis. Ectopic expression of an miR-26a mimic in osteoclast precursor cells attenuated osteoclast formation, actin-ring formation, and bone resorption by suppressing the expression of connective tissue growth factor/CCN family 2 (CTGF/CCN2), which can promote osteoclast formation via up-regulation of dendritic cell-specific transmembrane protein (DC-STAMP). On the other hand, overexpression of miR-26a inhibitor enhanced RANKL-induced osteoclast formation and function as well as CTGF expression. In addition, the inhibitory effect of miR-26a on osteoclast formation and function was prevented by treatment with recombinant CTGF. Collectively, our results suggest that miR-26a modulates osteoclast formation and function through the regulation of CTGF.