SYNTHESIS AND X-RAY CRYSTAL-STRUCTURE OF A MONOPENTAMETHYLCYCLOPENTADIENYL DERIVATIVE OF GADOLINIUM (NA(MU-2-THF)[(C5ME5)GD(THF)]2(MU-2-CL)3(MU-3-CL)2)2.6THF

The reaction of GdCl3 with 1 equiv of NaC5Me5 generates a neutral complex C5Me5GdCl2(THF)3 and a novel complex {Na(mu-2-THF)[(C5Me5)Gd(THF)]2(mu-2-Cl)3(mu-3-Cl)2}2.6THF whixh recrystallizes from THF in triclinic, the space group P1BAR with unit cell dimentions of a 12.183(4), b 13.638(6), c 17.883(7) angstrom, alpha-110.38(3), beta-94.04(3), gamma-99.44(3)-degrees, V 2721.20 angstrom-3 and D(calc) 1.43 g cm-3 for Z = 1. Least-squares refinement of 2170 observed reflections led to a final R value of 0.047. The title complex consists of two Na(mu-2-THF)[(C5Me5)Gd(THF)]2(mu-3-Cl)3(mu-3-Cl)2 units bridged together via two mu-2-THF to Na coordination. Each Gd ion is surrounded by one C5Me5 ligand, two mu-3-Cl, two mu-2-Cl and one THF in a distorted octahedral arrangement with average Gd-C(ring) 2.686(33), Gd-mu-2-Cl 2.724(7), Gd-mu-3-Cl 2.832(8) and Gd-O 2.407(11) angstrom. The sodium ion coordinates to two bridging THF, two mu-2-Cl and two mu-3-Cl to form a distorted octahedron with average Na-mu-2-O, Na-mu-2-Cl and Na-mu-3-Cl of 2.411(21), 2.807(15) and 2.845(12) angstrom, respectively.

Functional biosynthesis of an allophycocyan beta subunit in Escherichia coli

Allophycocyanin is a phycobiliprotein with various biological and pharmacological properties. An expression vector was constructed using CpeS as the bilin lyase for the allophycocyanin beta subunit, resulting in overexpression of a fluorescent allophycocyanin beta-subunit in Escherichia coli. A high-density cell culture was developed using a continuous feeding strategy. After 16 h of culture, the dry cell density reached 21.4 g 1(-1), the expression of the allophycocyanin beta-subunit was 0.86 g l(-1) broth, and the relative chromoprotein yield was 81.4%. The recombinant protein showed spectral features similar to native allophycocyanin, which provide an efficient methodology for large-scale production of this valuable fluorescent protein. (C) 2008, The Society for Biotechnology, Japan. All rights reserved.

Cloning and characterization of beta-carotene ketolase gene promoter in Haematococcus pluvialis

The unicellular green alga Haematococcus pluvialis accumulates a highly valuable ketocarotenoid, astaxanthin, under various environmental stresses. beta-carotene ketolase (BKT) plays a key role in astaxanthin biosynthesis in H. pluvialis. In this paper, an approximate 700 bp 5'-flanking region of the bkt gene containing a putative promoter was cloned through walking upstream. The results of the sequence analysis showed that this bkt 5'-flanking region might have cis-acting elements such as sterol regulatory element (SRE-1)-like motifs, the C-repeat/dehydration responsive element (DRE) and al-3 proximal element (APE)-like motifs, except for typical TATA and CCAAT boxes. The results of the P-galactosidase assay and the transient expression of lacZ driven by a series of sequential deletions revealed that a minimal promoter-like region might exist from -630 to -408 bp, and the highest promoter activity was observed to span the positions from -630 to -308 bp. The results of the site-directed mutagenesis of a C-repeat/DRE and two APE-like motifs in a promoter-like region (-630 to -308 bp) suggested that two APE-like motifs might be essential for transcriptional control of the bkt gene.

Molecular cloning and expression of interleukin 1beta (IL-1 beta) from red seabream (Pagrus major)

The interleukin 1beta (IL-1beta) cDNA was cloned from the red seabream (Pagrus major) by homology cloning strategy. A cDNA fragment was amplified by PCR using two degenerated primers, which were designed according to the conserved regions of other known IL-1beta sequences, and elongated by 3' ends and 5' ends RACE PCR to get the full length coding sequence of red seabream IL-1beta (RS IL-1beta). The sequence contained 1252 nucleotides that included a 5' untranslated region (UTR) of 84 bp, a 3' UTR of 410 bp and an open reading frame (ORF) of 759 nucleotides which could be translated into a putative peptide of 253 amino acids with molecular weight of 28.6 kD and putative isoelectric point pI of 5.29. The deduced peptide contained two potential N-glycosylation sites and an identifiable IL1 family signature, but lacked the signal peptide and the clear ICE cut site, which were common in other nonmammalian IL-1beta genes. The RS IL-1beta had the highest homology with piscine IL-1beta according to phylogenetic tree analysis. The transcript expression was detected in blood, brain, gill, heart, head kidney, kidney, liver, muscle and spleen in the pathogen challenged and healthy red seabream by RTPCR. Results showed that the RS IL-1beta mRNA was constitutively expressed in most of the tissues both in stimulated and un-stimulated fish, and the expression could be enhanced by pathogen challenging.

The recombination and expression of the allophycocyanin beta subunit gene in the chloroplast of Chlamydomonas reinhardtii

A Chlamydomonas reinhardtii (C. reinhardtii) chloroplast expression vector, papc-B, containing the apc-B gene that encodes the beta subunit of the light-harvesting antenna protein allophycocyanin (APC) of cyanobacteria, was constructed and transferred to the chloroplast genome of C. reinhardtii by the biolistic method. The transformants were identified by Southern blot, Western blot and ELISA assays after selection on resistant medium. The recombinant APC beta subunit was expressed in the C. reinhardtii chloroplast and accounted for up to 2-3% (w/w) of the total soluble protein (TSP), suggesting a promising prospect of using C. reinhardtii chloroplasts to produce functional plant-derived proteins.

Antimicrobial screening and active compound isolation from marine bacterium NJ6-3-1 associated with the sponge Hymeniacidon perleve

Twenty-nine marine bacterial strains were isolated from the sponge Hymeniacidon perleve at Nanji island, and antimicrobial screening showed that eight strains inhibited the growth of terrestrial microorganisms. The strain NJ6-3-1 with wide antimicrobial spectrum was identified as Pseudoalteromonas piscicida based on its 16S rRNA sequence analysis. The major antimicrobial metabolite, isolated through bioassay-guide fractionation of TLC bioautography overlay assay, was identified as norharman (a beta-carboline alkaloid) by EI-MS and NMR.

Crystal structure and DFT studies of a triazole derivative: 4-(2-hydrobenzylideneamino)-3-(1,2,4-triazol-4-yl-methyl) 1H-1,2,4-triazole-5 (4H)-thione

A novel triazole derivative 4-(2-hydrobenzylideneamino)-3-(1, 2, 4-triazol-4-ylmethyl)-1H-1, 2, 4-triazole-5 (4H)-thione(1) was synthesized and characterized using elemental analysis, MR, and H-1 NMR, and its crystal structure was determined via X-ray single crystal diffraction analysis. Crystal data: monoclinic, P2 (1)/c, a = 0.83335 (9) nm, b = 1. 49777 (16) run, c = 1. 14724 (12) nm, beta = 107. 990 (2)degrees, D = 1. 470 Mg/m(3), and Z = 4. The geometries and the vibrational frequencies were determined using the density functional theory(DFT) method at the B3LYP/6-31G* level. To demonstrate the accuracy of the reaction route of compound 1, one of the important intermediates was also tested using the same method. The structural parameters of the two compounds calculated using the DFT study are close to those of the crystals, and the harmonic vibrations of the two compounds computed via the DFT method are in good agreement with those in the observed IR spectral data. The thermodynamic properties of the title compound were calculated, and the compound shows a good structural stability at normal temperature. The test results of biological activities show that it has a certain bactericidal ability.

去甲肾上腺素参与吗啡神经适应性改变的中枢机制

That relapse still exists even after prolonged withdrawal is a difficult issue in the medical cure of drug addiction. Neuro-adaptation induced by prolonged exposure to addictive drugs is the neural mechanisms of both compulsive drug seeking and relapse.Neuro-adaptation caused by addictive drugs increases the individuals’ response to drugs and on the other hand, it reduces the response to natural reward in withdrawn individuals.There must be common neural mechanisms between the co-existing phenomena, and there must also be unique neural mechanisms in the drugs.To reveal the neuro-adaptation arising in the process from random, controllable drug-use to uncontrollable compulsive drug seeking is of great significance both theoretically and practically.Based on the above hypothesis, in order to reveal the function of alpha adrenergic receptor in compulsive drug-seeking motivation during the process of drug addiction, using sensitization of morphine-induced psychomotor activity as behavioral model, through the method of behavioral pharmacology, the neural mechanisms of alpha adrenergic receptor’s involvement in the process of addiction has been studied.The adjustment function caused by alpha receptors in medial prefrontal cortex and nucleus accumbens to morphine-induced psychomotor activity has been compared in the period of first use of drugs and in repetitive-use period. Furthermore, the effect on novelty seeking caused by alpha-receptors in relevant brain areas has also been compared. Major results are as follow: 1 After prolonged morphine exposure, rats’ response to morphine-induced psychomotor activity is strengthened and response to novel object induced reward weakened. 2 Injection of prazosin in medial prefrontal cortex will block morphine-induced psychomotor activity of naïve rats, however, it will not block that of morphine-withdrawn rats, but it will block the novelty seeking behavior of morphine-withdrawn rats. 3 Injection of clonidine in medial prefrontal cortex will block morphine-induced psychomotor effect of both naïve rats and morphine-withdrawn rats, and will block the novelty seeking behavior of morphine-withdrawn rats. 4 Injection of prazosin in nucleus accumbens will not affect the morphine-induced psychomotor effect of either naïve rats or morphine-withdrawn rats, nor will it affect the novelty seeking behavior of morphine-withdrawn rats. 5 Injection of clonidine in nucleus accumbens will block morphine-induced psychomotor effect of naïve rats, however, it will not block that of morphine-withdrawn rats, nor will it affect the novelty seeking behavior of morphine-withdrawn rats. These results show: 1 The weakening of the function of alpha1 receptors in medial prefrontal cortex and alpha2 receptors in nucleus accumbens caused by repetitive exposure to morphine is probably the cause of compulsive drug-seeking activity. 2 Blocking alpha1 receptors in medial prefrontal cortex accelerates the loss of interest in natural reward after morphine withdrawal. 3 Blocking alpha2 receptors in medial prefrontal cortex not only restrains drug-seeking motivation, but also blocks the individual’s seeking motivation for novelty stimulus, which suggests that, while selecting medicine for curing addiction, it should be considered to reduce the influence on natural reward as much as possible and to avoid major side-effect.

Exploitation of Ebola Virus VP35 Protein to identify new drugs counteracting its type I IFN antagonism

Ebolaviruses (EBOVs) are among the most virulent and deadly pathogens ever known, causing fulminant haemorrhagic fevers in humans and non-human primates. The 2014 outbreak of Ebola virus disease (EVD) in West Africa has claimed more lives than all previous EVD outbreaks combined. The EBOV high mortality rates have been related to the virus-induced impairment of the host innate immunity reaction due to two virus-coded proteins, VP24 and VP35. EBOV VP35 is a multifunctional protein, it is essential for viral replication as a component of the viral RNA polymerase and it also participates in nucleocapsid assembly. Early during EBOV infection, alpha-beta interferon (IFN-α/β) production would be triggered upon recognition of viral dsRNA products by cytoplasmic retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs). However, this recognition is efficiently prevented by the double-stranded RNA (dsRNA) binding activity of the EBOV VP35 protein, which hides RLRs binding sites on the dsRNA phosphate backbone as well the 5’-triphosphate (5’-ppp) dsRNA ends to RIG-I recognition. In addition to dsRNA binding and sequestration, EBOV VP35 inhibits IFN-α/β production preventing the activation of the IFN regulatory factor 3 (IRF-3) by direct interaction with cellular proteins. Previous studies demonstrated that single amino acid changes in the VP35 dsRNA binding domain reduce EBOV virulence, indicating that VP35 is an attractive target for antiviral drugs development. Within this context, here we report the establishment of a novel method to characterize the EBOV VP35 inhibitory function of the dsRNA-dependent RIG-I-mediated IFN-β signaling pathway in a BLS2 cell culture setting. In such system, a plasmid containing the promoter region of IFN-β gene linked with a luciferase reporter gene was transfected, together with a EBOV VP35 mammalian expression plasmid, into the IFN-sensitive A549 cell line, and the IFN-induction was stimulated through dsRNA transfection. Through alanine scanning mutational studies with biochemical, cellular and computational methods we highlighted the importance of some VP35 residues involved in dsRNA end-capping binding, such as R312, K282 and R322, that may serve as target for the development of small-molecule inhibitors against EBOV. Furthermore, we identified a synthetic compound that increased IFN-induction only under antiviral response stimulation and subverted VP35 inhibition, proving to be very attractive for the development of an antiviral drug. In conclusion, our results provide the establishment of a new assay as a straightforward tool for the screening of antiviral compounds that target i) dsRNA-VP35 or cellular protein-VP35 interaction and ii) dsRNA-dependent RIG-I-mediated IFN signaling pathway, in order to potentiate the IFN response against VP35 inhibition, setting the bases for further drug development.

Synthesis and reactivity of alpha-thio-beta-chloroacrylamides and alpha-thio-beta-chloroenones

Development of novel synthetic methodology for selective transformation of organic compounds is a central element underpinning organic synthesis with control of chemo-, regio- and stereoselectivity a very high priority. Reactions which can be conducted under mild reaction conditions and, ideally in an environmentally attractive manner, are particularly advantageous. The principal objective of this thesis was to explore the synthesis, reactivity and synthetic utility of a series of α,β-thio-β-chloroenones. The stereochemical features of these transformations and the potential of this novel series of compounds in the synthesis of bioactive compounds were of particular interest. In exploring the reactivity of these compounds, the key transformations included nucleophilic additions and Stille cross-coupling at the β-carbon. Chapter 1 reviews the literature relevant to the research conducted, and focuses in particular on the synthesis of β-chloroenones and related unsaturated carbonyl compounds. The synthesis of chalcone compounds from various precursors is also discussed, with particular emphasis on the use of palladium cross-coupling reactions in the preparation of these compounds. The biological activity of chalcones is also summarised in this chapter. The second chapter delineates the stereoselective synthesis of the novel α-thio-β-chloroenones from the corresponding α-thioketones in a multistep reaction cascade initiated by a NCS-mediated chlorination. A range of both alkyl and aryl β-chloroenones were prepared in this work and the oxidation of these compounds to the corresponding sulfoxides and sulfones is also outlined. The electrophilicity of the β-carbon of the enones was examined in nucleophilic addition/substitution reactions with successful access to a variety of synthetically useful novel adducts including acetals and enaminoketones. Investigation of the synthetic potential of the Stille cross-coupling reaction with the novel α-thio-β-chloroenones was explored and provided an efficient route for the synthesis of a novel series of chalcones. Most importantly this new methodology provided a new and synthetically powerful approach for carbon-carbon bond formation at the β-carbon under mild neutral conditions. A preliminary investigation into the use of these β-chloroenones as dienophiles in Diels-Alder cycloaddition reactions is also discussed in this chapter. Chapter 2 also reports the nucleophilic addition of N, O, S and C nucleophiles to previously described β-chloroacrylamides and their corresponding sulfoxide derivatives. This work builds on previous research carried out in this programme and the reactivity of these β-chloroacrylamides at the sulfide and sulfoxide level is compared. Comparison of the reactivity of the β-chloroacrylamides, in nucleophilic substitution and Stille-coupling, with that of the novel β-chloroenones is of interest. Finally, the biological activity of both the β-chloroenones and the β-chloroacrylamides in terms of cytotoxicity is summarised in Chapter 2. The final chapter, Chapter 3, details the full experimental procedures, including spectroscopic and analytical data for the compounds prepared during this research.

Akt signal transduction dysfunction in the 3xTg-AD mouse model of Alzheimer's disease

Alzheimer’s disease (AD) is an incurable neurodegenerative disorder, accounting for over 60% of all cases of dementia. The primary risk factor for AD is age, however several genetic and environmental factors are also involved. The pathological characteristics of AD include extracellular deposition of the beta-amyloid peptide (Aβ) and intraneuronal accumulation of neurofibrillary tangles (NFTs) made of aggregated paired helical filaments (PHFs) of the hyperphosphorylated tau protein, along with synaptic loss and neuronal death. There are numerous biochemical mechanisms involved in AD pathogenesis, however the reigning hypothesis points to toxic oligomeric Aβ species as the primary causative factor in a cascade of events leading to neuronal stress and dyshomeostasis that initiate abnormal regulation of tau. The insulin and IGF-1 receptors (IR, IGF-1R) are the primary activators of PI3- K/Akt through which they regulate cell growth, development, glucose metabolism, and learning and memory. Work in our lab and others shows increased Akt activity and phosphorylation of its downstream targets in AD brain, along with insulin and insulin-like growth factor-1 signalling (IIS) dysfunction. This is supported by studies of AD models in vivo and in vitro. Our group and others hypothesise that Aβ activates Akt through IIS to initiate a negative feedback mechanism that desensitises neurons to insulin/IGF-1, and sustains activation of Akt. In this study the functions of endogenous Akt, IR, and the insulin receptor substrate (IRS-1) were examined in relationship to Aβ and tau pathology in the 3xTg-AD mouse model, which contains three mutant human transgenes associated with familial AD or dementia. The 3xTg-AD mouse develops Aβ and tau pathology in a spatiotemporal manner that best recapitulates the progression of AD in human brain. Western blotting and immunofluorescent microscopy techniques were utilised in vivo and in vitro, to examine the relationship between IIS, Akt, and AD pathology. I first characterised in detail AD pathology in 3xTg-AD mice, where an age-related accumulation of intraneuronal Aβ and tau was observed in the hippocampal formation, amygdala, and entorhinal cortex, and at late stages (18 months), extracellular amyloid plaques and NFTs, primarily in the subiculum and the CA1 layer of the hippocampal formation. Increased activity of Akt, detected with antibody to phosphoSer473-Akt, was increased in 3xTg-AD mice compared to age-matched non-transgenic mice (non-Tg), and in direct correlation to the accumulation of Aβ and tau in neuronal somatodendritic compartments. Akt phosphorylates tau at residue Ser214 within a highly specific consensus sequence for Akt phosphorylation, and phosphoSer214-tau strongly decreases microtubule (MT) stabilisation by preventing tau-MT binding. PhosphoSer214-tau increased concomitantly with this in the same age-related and region-specific fashion. Polarisation of tau phosphorylation was observed, where PHF-1 (tauSer396/404) and phosphoSer214-tau both appeared early in 3xTg-AD mice in distinct neuronal compartments: PHF-1 in axons, and phosphoSer214-tau in neuronal soma and dendrites. At 18 months, phosphoSer214-tau strongly colocalised with NFTs positive for the PHF- 1 and AT8 (tauSer202/Thr205) phosphoepitopes. IR was decreased with age in 3xTg-AD brain and in comparison to age-matched non-Tg, and this was specific for brain regions containing Aβ, tau, and hyperactive Akt. IRS-1 was similarly decreased, and both proteins showed altered subcellular distribution. Phosphorylation of IRS-1Ser312 is a strong indicator of IIS dysfunction and insulin resistance, and was increased in 3xTg-AD mice with age and in relation to pathology. Of particular note was our observation that abberant IIS and Akt signalling in 3xTg-AD brain related to Aβ and tau pathology on a gross anatomical level, and specifically localised to the brain regions and circuitry of the perforant path. Finally, I conducted a preliminary study of the effects of synthetic Aβ oligomers on embryonic rat hippocampus neuronal cultures to support these results and those in the literature. Taken together, these novel findings provide evidence for IIS and Akt signal transduction dysfunction as the missing link between Aβ and tau pathogenesis, and contribute to the overall understanding of the biochemical mechanisms of AD.

An investigation into the role of Bcl-3 in toll-like receptor signalling

Through the recognition of potentially harmful stimuli, Toll-like receptors (TLRs) initiate the innate immune response and induce the expression of hundreds of immune and pro-inflammatory genes. TLRs are critical in mounting a defence against invading pathogens however, strict control of TLR signalling is vital to prevent host damage from excessive or prolonged immune activation. In this thesis the role of the IκB protein Bcl (B-cell lymphoma)-3 in the regulation of TLR signalling is investigated. Bcl3-/- mice and cells are hyper responsive to TLR stimulation and are defective in LPS tolerance. Bcl-3 interacts with and blocks the ubiquitination of homodimers of the NF-κB subunit, p50. Through stabilisation of inhibitory p50 homodimers, Bcl-3 negatively regulates NF-κB dependent inflammatory gene transcription following TLR activation. Firstly, we investigated the nature of the interaction between Bcl-3 and p50 and using peptide array technology. Key amino acids required for the formation of the p50:Bcl-3 immunosuppressor complex were identified. Furthermore, we demonstrate for the first time that interaction between Bcl-3 and p50 is necessary and sufficient for the anti-inflammatory properties of Bcl-3. Using the data generated from peptide array analysis we then generated cell permeable peptides designed to mimic Bcl-3 function and stabilise p50 homodimers. These Bcl-3 derived peptides are potent inhibitors of NF-κB dependent transcription activity in vitro and provide a solid basis for the development of novel gene-specific approaches in the treatment of inflammatory diseases. Secondly, we demonstrate that Bcl-3 mediated regulation of TLR signalling is not limited to NF-κB and identify the MAK3K Tumour Progression Locus (Tpl)-2 as a new binding partner of Bcl-3. Our data establishes role for Bcl-3 as a negative regulator of the MAPK-ERK pathway.

Short-lived alpha-helical intermediates in the folding of beta-sheet proteins.

Several lines of evidence point strongly toward the importance of highly alpha-helical intermediates in the folding of all globular proteins, regardless of their native structure. However, experimental refolding studies demonstrate no observable alpha-helical intermediate during refolding of some beta-sheet proteins and have dampened enthusiasm for this model of protein folding. In this study, beta-sheet proteins were hypothesized to have potential to form amphiphilic helices at a period of <3.6 residues/turn that matches or exceeds the potential at 3.6 residues/turn. Hypothetically, such potential is the basis for an effective and unidirectional mechanism by which highly alpha-helical intermediates might be rapidly disassembled during folding and potentially accounts for the difficulty in detecting highly alpha-helical intermediates during the folding of some proteins. The presence of this potential was confirmed, indicating that a model entailing ubiquitous formation of alpha-helical intermediates during the folding of globular proteins predicts previously unrecognized features of primary structure. Further, the folding of fatty acid binding protein, a predominantly beta-sheet protein that exhibits no apparent highly alpha-helical intermediate during folding, was dramatically accelerated by 2,2,2-trifluoroethanol, a solvent that stabilizes alpha-helical structure. This observation suggests that formation of an alpha-helix can be a rate-limiting step during folding of a predominantly beta-sheet protein and further supports the role of highly alpha-helical intermediates in the folding of all globular proteins.

The dopamine metabolite 3-methoxytyramine is a neuromodulator.

Dopamine (3-hydroxytyramine) is a well-known catecholamine neurotransmitter involved in multiple physiological functions including movement control. Here we report that the major extracellular metabolite of dopamine, 3-methoxytyramine (3-MT), can induce behavioral effects in a dopamine-independent manner and these effects are partially mediated by the trace amine associated receptor 1 (TAAR1). Unbiased in vivo screening of putative trace amine receptor ligands for potential effects on the movement control revealed that 3-MT infused in the brain is able to induce a complex set of abnormal involuntary movements in mice acutely depleted of dopamine. In normal mice, the central administration of 3-MT caused a temporary mild hyperactivity with a concomitant set of abnormal movements. Furthermore, 3-MT induced significant ERK and CREB phosphorylation in the mouse striatum, signaling events generally related to PKA-mediated cAMP accumulation. In mice lacking TAAR1, both behavioral and signaling effects of 3-MT were partially attenuated, consistent with the ability of 3-MT to activate TAAR1 receptors and cause cAMP accumulation as well as ERK and CREB phosphorylation in cellular assays. Thus, 3-MT is not just an inactive metabolite of DA, but a novel neuromodulator that in certain situations may be involved in movement control. Further characterization of the physiological functions mediated by 3-MT may advance understanding of the pathophysiology and pharmacology of brain disorders involving abnormal dopaminergic transmission, such as Parkinson's disease, dyskinesia and schizophrenia.

Beta-arrestins regulate atherosclerosis and neointimal hyperplasia by controlling smooth muscle cell proliferation and migration.

Atherosclerosis and arterial injury-induced neointimal hyperplasia involve medial smooth muscle cell (SMC) proliferation and migration into the arterial intima. Because many 7-transmembrane and growth factor receptors promote atherosclerosis, we hypothesized that the multifunctional adaptor proteins beta-arrestin1 and -2 might regulate this pathological process. Deficiency of beta-arrestin2 in ldlr(-/-) mice reduced aortic atherosclerosis by 40% and decreased the prevalence of atheroma SMCs by 35%, suggesting that beta-arrestin2 promotes atherosclerosis through effects on SMCs. To test this potential atherogenic mechanism more specifically, we performed carotid endothelial denudation in congenic wild-type, beta-arrestin1(-/-), and beta-arrestin2(-/-) mice. Neointimal hyperplasia was enhanced in beta-arrestin1(-/-) mice, and diminished in beta-arrestin2(-/-) mice. Neointimal cells expressed SMC markers and did not derive from bone marrow progenitors, as demonstrated by bone marrow transplantation with green fluorescent protein-transgenic cells. Moreover, the reduction in neointimal hyperplasia seen in beta-arrestin2(-/-) mice was not altered by transplantation with either wild-type or beta-arrestin2(-/-) bone marrow cells. After carotid injury, medial SMC extracellular signal-regulated kinase activation and proliferation were increased in beta-arrestin1(-/-) and decreased in beta-arrestin2(-/-) mice. Concordantly, thymidine incorporation and extracellular signal-regulated kinase activation and migration evoked by 7-transmembrane receptors were greater than wild type in beta-arrestin1(-/-) SMCs and less in beta-arrestin2(-/-) SMCs. Proliferation was less than wild type in beta-arrestin2(-/-) SMCs but not in beta-arrestin2(-/-) endothelial cells. We conclude that beta-arrestin2 aggravates atherosclerosis through mechanisms involving SMC proliferation and migration and that these SMC activities are regulated reciprocally by beta-arrestin2 and beta-arrestin1. These findings identify inhibition of beta-arrestin2 as a novel therapeutic strategy for combating atherosclerosis and arterial restenosis after angioplasty.