Extracellular Research Articles

Long Non-Coding RNAs, Ubiquitin Proteasome System, Collagen Degradation and Preterm Premature Rupture of Membrane

Preterm Premature Rupture of the Fetal Membranes (PPROM) is a reproductive system disorder and a major cause of prematurity. Several major etiologic factors have been linked to PPROM, one of which is the weakness of the amniochorion Extra Cellular Matrix (ECM) caused by collagen degradation. With increasingly deeper research studies on the human genome, rapidly growing evidence has suggested that abnormally expressed non-coding RNAs (ncRNAs) are involved with multiple diseases. Among various ncRNAs, the long non-coding RNAs (lncRNAs) have attracted more attention and were found to correlate with various inflammation-related conditions or diseases. Recent studies demonstrated that lncRNAs might be involved in regulation of the ubiquitin proteasome system (UPS) in PPROM. The UPS is an ATP-dependent enzyme process that targets substrate proteins, tagged with an isopeptide chain composed of covalently linked molecules of ubiquitin, for degradation by the 26S proteasome, and deeply involved in the regulation of most basic cellular processes. Here, we reviewed the UPS system, the collagen in extracellular matrix (ECM), the PPROM as well as lncRNAs. We hypothesize that a novel pathogenic pathway of “infection/inflammation lncRNA, UPS, collagen, membrane rupture” for exploring the molecular pathogenesis of PPROM

Peptide-Assisted Directional Adsorption of Purple Membrane at the Liquid–Solid Interface

We report here an approach of directional adsorption of purple membrane (PM) on liquid–solid interfaces modified by peptide assemblies. Bacteriorhodopsin (bR) is the only protein in PM that can transport protons directionally from the cytoplasmic (CP) side to the extracellular (EC) side to achieve chemical energy for life and growth. Controlled adsorption of PM is critical to exploring novel properties in many areas, such as data storage, biosolar devices, and sensors. Here, we obtained oriented PM adsorption at the liquid–solid interface by modification with de novo peptides. EFM was utilized to distinguish the two sides of PM by measuring the surface potential of PM because of its high resolution in differentiating electrical characteristics. Furthermore, we confirmed the modulating effect by photoelectrical responses under laser irradiation.

Differential dynamics of extracellular and cytoplasmic domains in denatured States of rhodopsin.

Rhodopsin is a model system for understanding membrane protein folding. Recently, conditions that allow maximally denaturing rhodopsin without causing aggregation have been determined, opening the door to the first structural characterization of denatured states of rhodopsin by nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) spectroscopy. One-dimensional 1H NMR spectra confirm a progressive increase in flexibility of resonances in rhodopsin with increasing denaturant concentrations. Two-dimensional 1H–15N HSQC spectra of [15N]-α-lysine-labeled rhodopsin in which signals arise primarily from residues in the cytoplasmic (CP) domain and of [15N]-α,ε-tryptophan-labeled rhodopsin in which signals arise only from transmembrane (TM) and extracellular (EC) residues indicate qualitatively that EC and CP domains may be differentially affected by denaturation. To obtain residue-specific information, particular residues in EC and CP domains were investigated by site-directed spin labeling. EPR spectra of the spin-labeled samples indicate that the EC residues retain more rigidity in the denatured states than the CP residues. These results support the notion of residual structure in denatured states of rhodopsin.

SR-BI/CD36 chimeric receptors define extracellular subdomains of SR-BI critical for cholesterol transport.

High-density lipoproteins (HDLs) are athero-protective, primarily because of their ability to promote cholesterol flux from peripheral tissues to the liver by reverse cholesterol transport (RCT). The delivery of HDL-cholesteryl esters (CE) into cells is mediated by the HDL receptor, scavenger receptor class B type I (SR-BI), a promising target for enhancing whole body cholesterol disposal and preventing cardiovascular disease. A detailed understanding of the structural determinants underlying proper SR-BI/HDL alignment that supports the selective uptake of HDL-CE into cells remains lacking. To this end, we exploited CD36, a class B scavenger receptor with a predicted topology similar to that of SR-BI that binds HDL but is unable to mediate efficient selective uptake of HDL-CE. We generated a series of SR-BI/CD36 chimeric receptors that span the extracellular (EC) domain of SR-BI to delineate regions that are essential for SR-BI’s cholesterol transport functions. All 16 SR-BI/CD36 chimeras were transiently expressed in COS-7 cells, and their plasma membrane localization was confirmed. The majority of SR-BI/CD36 chimeric receptors displayed significant reductions in their ability to (i) bind HDL, (ii) deliver HDL-CE to cells, (iii) mediate efflux of free cholesterol (FC) to HDL, and (iv) redistribute plasma membrane domains of FC. We also demonstrated that changes in SR-BI function were independent of receptor oligomerization. Altogether, we have identified discrete subdomains, particularly in the N-terminal and C-terminal regions of the EC domain of SR-BI, that are critical for productive receptor–ligand interactions and the various cholesterol transport functions of SR-BI.

His166 is the Schiff base proton acceptor in attractant phototaxis receptor sensory rhodopsin I.

Photoactivation of attractant phototaxis receptor sensory rhodopsin I (SRI) in Halobacterium salinarum entails transfer of a proton from the retinylidene chromophore’s Schiff base (SB) to an unidentified acceptor residue on the cytoplasmic half-channel, in sharp contrast to other microbial rhodopsins, including the closely related repellent phototaxis receptor SRII and the outward proton pump bacteriorhodopsin, in which the SB proton acceptor is an aspartate residue salt-bridged to the SB in the extracellular (EC) half-channel. His166 on the cytoplasmic side of the SB in SRI has been implicated in the SB proton transfer reaction by mutation studies, and mutants of His166 result in an inverted SB proton release to the EC as well as inversion of the protein’s normally attractant phototaxis signal to repellent. Here we found by difference Fourier transform infrared spectroscopy the appearance of Fermi-resonant X–H stretch modes in light-minus-dark difference spectra; their assignment with 15N labeling and site-directed mutagenesis demonstrates that His166 is the SB proton acceptor during the photochemical reaction cycle of the wild-type SRI–HtrI complex.

Taurine supplementation reduces blood pressure and prevents endothelial dysfunction and oxidative stress in post-weaning protein-restricted rats.

IntroductionTaurine is a sulfur-containing amino acid that exerts protective effects on vascular function and structure in several models of cardiovascular diseases through its antioxidant and anti-inflammatory properties. Early protein malnutrition reprograms the cardiovascular system and is linked to hypertension in adulthood. This study assessed the effects of taurine supplementation in vascular alterations induced by protein restriction in post-weaning rats.Methods and ResultsWeaned male Wistar rats were fed normal- (12%, NP) or low-protein (6%, LP) diets for 90 days. Half of the NP and LP rats concomitantly received 2.5% taurine supplementation in the drinking water (NPT and LPT, respectively). LP rats showed elevated systolic, diastolic and mean arterial blood pressure versus NP rats; taurine supplementation partially prevented this increase. There was a reduced relaxation response to acetylcholine in isolated thoracic aortic rings from the LP group that was reversed by superoxide dismutase (SOD) or apocynin incubation. Protein expression of p47phox NADPH oxidase subunit was enhanced, whereas extracellular (EC)-SOD and endothelial nitric oxide synthase phosphorylation at Ser 1177 (p-eNOS) were reduced in aortas from LP rats. Furthermore, ROS production was enhanced while acetylcholine-induced NO release was reduced in aortas from the LP group. Taurine supplementation improved the relaxation response to acetylcholine and eNOS-derived NO production, increased EC-SOD and p-eNOS protein expression, as well as reduced ROS generation and p47phox expression in the aortas from LPT rats. LP rats showed an increased aortic wall/lumen ratio and taurine prevented this remodeling through a reduction in wall media thickness.ConclusionOur data indicate a protective role of taurine supplementation on the high blood pressure, endothelial dysfunction and vascular remodeling induced by post-weaning protein restriction. The beneficial vascular effect of taurine was associated with restoration of vascular redox homeostasis and improvement of NO bioavailability.

Herpes simplex virus gE/gI extracellular domains promote axonal transport and spread from neurons to epithelial cells.

Following reactivation from latency, there are two distinct steps in the spread of herpes simplex virus (HSV) from infected neurons to epithelial cells: (i) anterograde axonal transport of virus particles from neuron bodies to axon tips and (ii) exocytosis and spread of extracellular virions across cell junctions into adjacent epithelial cells. The HSV heterodimeric glycoprotein gE/gI is important for anterograde axonal transport, and gE/gI cytoplasmic domains play important roles in sorting of virus particles into axons. However, the roles of the large (∼400-residue) gE/gI extracellular (ET) domains in both axonal transport and neuron-to-epithelial cell spread have not been characterized. Two gE mutants, gE-277 and gE-348, contain small insertions in the gE ET domain, fold normally, form gE/gI heterodimers, and are incorporated into virions. Both gE-277 and gE-348 did not function in anterograde axonal transport; there were markedly reduced numbers of viral capsids and glycoproteins compared with wild-type HSV. The defects in axonal transport were manifest in neuronal cell bodies, involving missorting of HSV capsids before entry into proximal axons. Although there were diminished numbers of mutant gE-348 capsids and glycoproteins in distal axons, there was efficient spread to adjacent epithelial cells, similar to wild-type HSV. In contrast, virus particles produced by HSV gE-277 spread poorly to epithelial cells, despite numbers of virus particles similar to those for HSV gE-348. These results genetically separate the two steps in HSV spread from neurons to epithelial cells and demonstrate that the gE/gI ET domains function in both processes. An essential phase of the life cycle of herpes simplex virus (HSV) and other alphaherpesviruses is the capacity to reactivate from latency and then spread from infected neurons to epithelial tissues. This spread involves at least two steps: (i) anterograde transport to axon tips followed by (ii) exocytosis and extracellular spread from axons to epithelial cells. HSV gE/gI is a glycoprotein that facilitates this virus spread, although by poorly understood mechanisms. Here, we show that the extracellular (ET) domains of gE/gI promote the sorting of viral structural proteins into proximal axons to begin axonal transport. However, the gE/gI ET domains also participate in the extracellular spread from axon tips across cell junctions to epithelial cells. Understanding the molecular mechanisms involved in gE/gI-mediated sorting of virus particles into axons and extracellular spread to adjacent cells is fundamentally important for identifying novel targets to reduce alphaherpesvirus disease.

Differences in Allosteric Communication Pipelines in the Inactive and Active States of a GPCR

G-protein-coupled receptors (GPCRs) are membrane proteins that allosterically transduce the signal of ligand binding in the extracellular (EC) domain to couple to proteins in the intracellular (IC) domain. However, the complete pathway of allosteric communication from the EC to the IC domain, including the role of individual amino acids in the pathway is not known. Using the correlation in torsion angle movements calculated from microseconds-long molecular-dynamics simulations, we elucidated the allosteric pathways in three different conformational states of β2-adrenergic receptor (β2AR): 1), the inverse-agonist-bound inactive state; 2), the agonist-bound intermediate state; and (3), the agonist- and G-protein-bound fully active state. The inactive state is less dynamic compared with the intermediate and active states, showing dense clusters of allosteric pathways (allosteric pipelines) connecting the EC with the IC domain. The allosteric pipelines from the EC domain to the IC domain are weakened in the intermediate state, thus decoupling the EC domain from the IC domain and making the receptor more dynamic compared with the other states. Also, the orthosteric ligand-binding site becomes the initiator region for allosteric communication in the intermediate state. This finding agrees with the paradigm that the nature of the agonist governs the specific signaling state of the receptor. These results provide an understanding of the mechanism of allosteric communication in class A GPCRs. In addition, our analysis shows that mutations that affect the ligand efficacy, but not the binding affinity, are located in the allosteric pipelines. This clarifies the role of such mutations, which has hitherto been unexplained.

Reproducibility of a quantitative cutaneous cytological technique.

Cutaneous cytology is a valuable tool for diagnosis of canine superficial pyoderma. Current published reproducible techniques are semiquantitative. The aim of this study was to evaluate the reproducibility of a quantitative method for skin surface cytology in dogs with superficial pyoderma. Impression smears were collected from five normal dogs and 20 dogs with clinical and cytological evidence of superficial pyoderma. Four investigators evaluated 10 oil immersion fields (OIF) on 25 slides, selecting fields with inflammatory cells, nuclear streaming and or keratinocytes under ×10 magnification. Investigators repeated blinded evaluations of all slides at least twice. For each OIF, polymorphonuclear leukocytes (PMNs), intracellular (IC) cocci, extracellular (EC) cocci, IC rods, EC rods and yeast were quantified. Nuclear streaming was scored as present or absent. For each parameter, within-reader and between-reader agreements were expressed by the intraclass correlation (ICC) value (≤0.20 poor, 0.21-0.40 fair, 0.41-0.60 moderate, 0.61-0.80 good and 0.81-1.00 excellent) or kappa statistic (κ). Reproducible parameters included: PMNs (ICC=0.58), nuclear streaming (ICC=0.68), EC cocci (ICC=0.64) and IC cocci (ICC=0.32). When qualified as present or absent, within-reader κ for IC cocci was 0.71. The method demonstrated 93% sensitivity in identifying dogs with superficial pyoderma and 51% specificity in identifying normal dogs according to established criteria. However, if criteria for normal dogs were limited to the absence of PMNs and IC bacteria, sensitivity of 64% and specificity of 98% were demonstrated. For several parameters, including PMNs, nuclear streaming, EC cocci and IC cocci, a reproducible, quantitative cytological technique was identified.

P-0054 - The Change of Serum HER2 Extra Cellular Domain Concentration Before and After Resection in Operable Gastric Cancer Patients in Japan; Consider Relations with Pathological HER2 Status by IHC and Fish

Introduction: HER2 extra cellular domain (ECD) can be detected in the serum of healthy person, these concentrations are raised in the patients with cancer; this is dependent on tumor HER2 status and tumor burden. In previous reports, serum HER2-ECD status is useful for judgement of efficacy of anti-HER2 therapy in patients with HER2-positive breast cancer. Although, similarly to breast cancer, approximately 20% gastric cancer show HER2 amplification or overexpression and the efficacy of trastuzumab has been reported, we don't have enough date for serum HER2-ECD of gastric cancer patients.

Covalent and Density-Controlled Surface Immobilization of E-Cadherin for Adhesion Force Spectroscopy

E-cadherin is a key cell-cell adhesion molecule but the impact of receptor density and the precise contribution of individual cadherin ectodomains in promoting cell adhesion are only incompletely understood. Investigating these mechanisms would benefit from artificial adhesion substrates carrying different cadherin ectodomains at defined surface density. We therefore developed a quantitative E-cadherin surface immobilization protocol based on the SNAP-tag technique. Extracellular (EC) fragments of E-cadherin fused to the SNAP-tag were covalently bound to self-assembled monolayers (SAM) of thiols carrying benzylguanine (BG) head groups. The adhesive functionality of the different E-cadherin surfaces was then assessed using cell spreading assays and single-cell (SCSF) and single-molecule (SMSF) force spectroscopy. We demonstrate that an E-cadherin construct containing only the first and second outmost EC domain (E1-2) is not sufficient for mediating cell adhesion and yields only low single cadherin-cadherin adhesion forces. In contrast, a construct containing all five EC domains (E1-5) efficiently promotes cell spreading and generates strong single cadherin and cell adhesion forces. By varying the concentration of BG head groups within the SAM we determined a lateral distance of 5–11 nm for optimal E-cadherin functionality. Integrating the results from SCMS and SMSF experiments furthermore demonstrated that the dissolution of E-cadherin adhesion contacts involves a sequential unbinding of individual cadherin receptors rather than the sudden rupture of larger cadherin receptor clusters. Our method of covalent, oriented and density-controlled E-cadherin immobilization thus provides a novel and versatile platform to study molecular mechanisms underlying cadherin-mediated cell adhesion under defined experimental conditions.

3D Blood Pressure Pulse Analyzer로 측정한 맥파 에너지와 산후 부종과의 상관성 연구

Purpose: This study was performed to find correlations between Edema Index and Pulse Energy in early postpartum period. Methods: Fiftynine postpartum women were participated in this study which was conducted with Inbody 720 (Biospace Co. Ltd) and 3D Blood Pressure Pulse Analyzer (3D-MAC). Edema Index (Extra Cellular Water/Total Body Water) calculated after body composition analysis and 3D-MAC result (Pulse Energy) were analysed within a week after delivery. Results: The results were as follows 1. Edema Indexes of the upper, lower limbs, trunk and whole body were associated with each other respectively. 2. Edema Indexes and Right Kwan pulse energy had significant positive correlation. 3. Right Kwan pulse energy showed positive correlations with Left Kwan, Right Chon, Right Cheok. Conclusions: Viscera associated with Postpartum Edema are Spleen, Lung, Liver and Vital Gate. The most important thing is thought to be Spleen.

Cardiac T 1 Imaging

T(1) mapping of the heart has evolved into a valuable tool to evaluate myocardial tissue properties, with or without contrast injection, including assessment of myocardial edema and free water content, extracellular volume (expansion), and most recently cardiomyocyte hypertrophy. The magnetic resonance imaging pulse sequence techniques developed for these applications have had to address at least 2 important considerations for cardiac applications: measure magnetization-inversion recoveries during cardiac motion with sufficient temporal resolution for the shortest expected T(1) values, and, second, obtain these measurements within a time during which a patient can comfortably suspend breathing. So-called Look-Locker techniques, and variants thereof, which all sample multiple points of a magnetization recovery after each magnetization preparation, have therefore become a mainstay in this field. The rapid pace of advances and new findings based on cardiac T(1) mapping for assessment of diffuse fibrosis or myocardial edema show that these techniques enrich the capabilities of magnetic resonance imaging for myocardial tissue profiling, which is arguably unmatched by other cardiac imaging modalities.

High affinity IgE-Fc receptor α and γ subunit interactions.

To explore the relationships between the subunits (α, β and γ) of the high affinity IgE receptor (Fc&RI) and its ability to mediate transmembrane signaling. Experimental study. Department of Molecular Biology and Biotechnology, University of Sheffield, UK, from 2008 to 2009. The approach employed was to create a chimera (human αγγ) using the extracellular (EC) domain of the human high affinity IgE receptor. The alpha subunit (huFc&RIα) of IgE receptor was spliced onto the rodent gamma TM and cytoplasmic domain (CD). This was transfected into the Rat Basophilic Leukemia cell line in order to assess the possibility of selectively activating cells transfected with this single pass construct for antigen induced mediator release. The RBLs cell lines transfected with the huFc&RIα/γ/γ cDNA constructs were assessed for the cell surface expression of the huFc&RIα subunit and the response to the antigenic stimulus by looking for degranulation and intracellular Ca2+ mobilisation. The results obtained showed the absence of huFc&RIα subunit expression on the surface of transfected cells as seen by flowcytometric studies, β-hexosaminidase assays and intracellular calcium mobilisation studies. In the present study the grounds for non-expression of huFc&RIα/γ/γ cDNA remains elusive but may be due to the fact that the human-rodent chimeric receptors are assembled differently than the endogenous rodent receptors as seen in study in which COS 7 cells were transfected with human/rat chimeric complexes.

Quantification of the stiffness and strength of cadherin ectodomain binding with different ions

The stiffness and strength of extracellular (EC) region of cadherin are proposed to be two important mechanical properties both for cadherin as a mechanotransductor and for the formation of cell-cell adhesion. In this study, we quantitatively characterized the stiffness and strength of EC structure when it binds with different types of ions by molecular dynamics simulations. Results show that EC structure exhibits a rod-like shape with high stiffness and strength when it binds with the bivalent ions of calcium or magnesium. However, it switches to a soft and collapsed conformation when it binds with the monovalent ions of sodium or potassium. This study sheds light on the important role of the bivalent ions of calcium in the physiological function of EC.

Mapping Allosteric Communication Pipelines in GPCRs from Microsecond Timescale Molecular Dynamics Simulations

G protein coupled receptors (GPCRs) are 7 transmembrane (TM) helical proteins that signal through effector proteins bound at the intracellular (IC) interface. Agonist binding at the extracellular (EC) domain triggers conformational change at the IC domain leading to receptor activation. However, the mechanism of allosteric communication and the amino acids involved in the pipelines of allosteric communication (allosteric pathways) are not known yet. In this study, we have mapped the allosteric pipelines of communication in β2-adrenergic receptor (β2AR) using microseconds timescale Molecular Dynamics trajectories. Using mutual information in the internal coordinates, we have compared the allosteric pipelines among three β2AR conformations; inverse agonist bound inactive state, agonist bound intermediate state, and agonist and G protein bound active state. Strong allosteric communication along the TM domains stabilize the receptor in the inactive and active conformations. However the agonist bound intermediate state is dynamic showing weakened communication between the EC and IC domains. We have identified the residues that mediate multiple allosteric pipelines as allosteric hubs. These allosteric hubs have also been identified with the mutations that alter the receptor efficacy without altering the ligand binding. The role of such mutations were not previously understood.We have identified the residue networks involved in a continuous communication pipeline from the EC loops to the G protein coupling site. One of the termination points of the activation signal is the engineered Zn2+ binding site at the IC interface, which is a known positive allosteric modulator binding site in β2AR. We have shown how our method in conjunction with MD simulations can identify allosteric pockets which can then be used for screening allosteric drugs in GPCRs.

Mapping Mechanical Properties of the Extra Cellular Matrix Surrounding Cells Cultured in 3D

There is a preponderance of evidence for roles of bulk stromal stiffness in cell regulation, but little is about the mechanical microenvironment. To investigate these roles we culture cells within 3D extracellular matrix (ECM) hydrogels. We implement automated optical tweezers active microrheology (aAMR) to probe extracellular stiffness and map it in the volume surrounding cells. Our aAMR uses optical forces acting on microbeads to measure the complex response function of the ECM surrounding each bead. Hundreds of beads are probed in one hour to map the mechanical landscape and to seek correlations between local stiffness and cell properties such as contractility, signaling and differentiation. For example, we will present our study of primary human aortic smooth muscle cells (AoSMCs) cultured within a collagen hydrogel. We observed a range of stiffness from over 200 Pa to less than 20 Pa, with the stiffer regions near the leading edge of the cell. Such stiffening is consistent with the non-linear stress-strain relationship of natural tissue in which stiffness increases with stretch. After treatment with inhibitors of contractility such as blebbistatin or the ROCK Inhibitor Y-27632, we observed cell relaxation coincident with a distribution of softer values ranging from 100 to ∼10 Pa. Such leading edge contractile force-dependent stiffness is consistent with our earlier findings for primary mesenchymal stem cells and an invasive capillary morphogenesis model, in which only several beads could be measured in one hour due to the notable complexity of performing AMR. In contrast, our aAMR densely measures ECM stiffness, chronically, and is a new research tool for studying the interplay between viscoelastic properties, forces and signaling at the ECM-cell interface.

Exopolysaccharide quantification.

The extracellular (EC) matrix is a key feature of mature P. aeruginosa biofilms. Exopolysaccharides are considered as major components of this biofilm matrix. They include alginate, LPS, glucans, and psl- and pel-dependent products. Here, we describe a method of quantification of the psl-dependent mannose-rich exopolysaccharide, based on the quantification of mannose in carbohydrate-enriched cell-associated extracts and growth media. Mannose is quantified by GC or GC-MS with an internal standard, after acid hydrolysis and conversion into volatile alditol acetates.

Allosteric Modulators Hit the TSH Receptor

The receptor for TSH (TSHR) has captured our interest and imagination since it was first demonstrated to be a major human antigen in autoimmune thyroid disease. The original realization that the immunoglobulin fraction of sera from patients with Graves' disease incorporated unique human autoantibodies to the TSHR led to the unraveling of the great complexity that the TSHR exhibits in comparison with its orthologous partners; the LH and FSH receptors (1, 2). The TSHR is a member of the class A G-protein coupled receptor (GPCR) family with 7 transmembrane regions. The holoreceptor consists of 764 amino acids divided into a large, highly glycosylated, ectodomain of 415 amino acids incorporating 11 leucine rich repeats and which has been crystallized bound to a stimulating TSHR antibody (3). The ectodomain is linked to a distal signal-specific domain, which is a hinge region of 130 amino acids. The hinge region is attached to a transmembrane domain (TMD) of 349 amino acids typical of the GPCR family incorporating 7 transmembrane helices (TMHs) joined by extracellular (ECL) and intracellular (ICL) loops (Figure 1).

EC4, a truncation of soluble N-cadherin, reduces vascular smooth muscle cell apoptosis and markers of atherosclerotic plaque instability

Atherosclerotic plaque instability is precipitated by vascular smooth muscle cell apoptosis in the fibrous cap, weakening it and leading to plaque rupture. We previously showed that reducing smooth muscle cell apoptosis with soluble N-cadherin (SNC) increased features of plaque stability. We have now identified the active site of SNC and examined whether a truncated form containing this site retains the antiapoptotic effect. SNC was mutated to prevent interaction with N-cadherin or fibroblast growth factor receptor (FGFR). Interaction with FGFR in the extracellular (EC) 4 domain of SNC was essential for the antiapoptotic effect. Therefore, we made a truncated form consisting of the EC4 domain. EC4 significantly reduced smooth muscle cell, macrophage, and endothelial cell apoptosis in vitro by ~70%, similar to SNC. Elevation of plasma levels of EC4 in male apolipoprotein E–deficient mice with existing atherosclerosis significantly reduced apoptosis in brachiocephalic artery plaques by ~50%. EC4 reduced plaque size and the incidence of buried fibrous layers and the macrophage:smooth muscle cell ratio (surrogate markers of plaque instability). Interaction of EC4 with FGFR induced potent antiapoptotic signaling in vitro and in vivo. EC4 modulates atherosclerosis in mice demonstrating its therapeutic potential for retarding plaque size and instability.