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- Moretti, Rocco, et al.
(author)
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Community-wide evaluation of methods for predicting the effect of mutations on protein-protein interactions
- 2013
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In: Proteins. - : Wiley. - 0887-3585 .- 1097-0134. ; 81:11, s. 1980-1987
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Journal article (peer-reviewed)abstract
- Community-wide blind prediction experiments such as CAPRI and CASP provide an objective measure of the current state of predictive methodology. Here we describe a community-wide assessment of methods to predict the effects of mutations on protein-protein interactions. Twenty-two groups predicted the effects of comprehensive saturation mutagenesis for two designed influenza hemagglutinin binders and the results were compared with experimental yeast display enrichment data obtained using deep sequencing. The most successful methods explicitly considered the effects of mutation on monomer stability in addition to binding affinity, carried out explicit side-chain sampling and backbone relaxation, evaluated packing, electrostatic, and solvation effects, and correctly identified around a third of the beneficial mutations. Much room for improvement remains for even the best techniques, and large-scale fitness landscapes should continue to provide an excellent test bed for continued evaluation of both existing and new prediction methodologies. Proteins 2013; 81:1980-1987.
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- Ghavami, Saeid, et al.
(author)
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Autophagy regulates trans fatty acid-mediated apoptosis in primary cardiac myofibroblasts.
- 2012
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In: Biochimica et Biophysica Acta. Molecular Cell Research. - : Elsevier BV. - 0167-4889 .- 1879-2596. ; 1823:12, s. 2274-2286
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Journal article (peer-reviewed)abstract
- Trans fats are not a homogeneous group of molecules and less is known about the cellular effects of individual members of the group. Vaccenic acid (VA) and elaidic acid (EA) are the predominant trans monoenes in ruminant fats and vegetable oil, respectively. Here, we investigated the mechanism of cell death induced by VA and EA on primary rat ventricular myofibroblasts (rVF). The MTT assay demonstrated that both VA and EA (200μM, 0-72h) reduced cell viability in rVF (P<0.001). The FACS assay confirmed that both VA and EA induced apoptosis in rVF, and this was concomitant with elevation in cleaved caspase-9, -3 and -7, but not caspase-8. VA and EA decreased the expression ratio of Bcl2:Bax, induced Bax translocation to mitochondria and decrease in mitochondrial membrane potential (Δψ). BAX and BAX/BAK silencing in mouse embryonic fibroblasts (MEF) inhibited VA and EA-induced cell death compared to the corresponding wild type cells. Transmission electron microscopy revealed that VA and EA also induced macroautophagosome formation in rVF, and immunoblot analysis confirmed the induction of several autophagy markers: LC3-β lipidation, Atg5-12 accumulation, and increased beclin-1. Finally, deletion of autophagy genes, ATG3 and ATG5 significantly inhibited VA and EA-induced cell death (P<0.001). Our findings show for the first time that trans fat acid (TFA) induces simultaneous apoptosis and autophagy in rVF. Furthermore, TFA-induced autophagy is required for this pro-apoptotic effect. Further studies to address the effect of TFA on the heart may reveal significant translational value for prevention of TFA-linked heart disease.
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- Schriefl, A. J., et al.
(author)
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Remodeling of Intramural Thrombus and Collagen in an Ang-II Infusion ApoE-/- Model of Dissecting Aortic Aneurysms
- 2012
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In: Thrombosis Research. - : Elsevier BV. - 0049-3848 .- 1879-2472. ; 130:3, s. E139-E146
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Journal article (peer-reviewed)abstract
- Fibrillar collagen endows the normal aortic wall with significant stiffness and strength and similarly plays important roles in many disease processes. For example, because of the marked loss of elastic fibers and functional smooth cells in aortic aneurysms, collagen plays a particularly important role in controlling the dilatation of these lesions and governing their rupture potential. Recent findings suggest further that collagen remodeling may also be fundamental to the intramural healing of arterial or aneurysmal dissections. To explore this possibility further, we identified and correlated regions of intramural thrombus and newly synthesized fibrillar collagen in a well-established mouse model of dissecting aortic aneurysms. Our findings suggest that intramural thrombus that is isolated from free-flowing blood creates a permissive environment for the synthesis of fibrillar collagen that, albeit initially less dense and organized, could protect that region of the dissected wall from subsequent expansion of the dissection or rupture. Moreover, alpha-smooth muscle actin positive cells appeared to be responsible for the newly produced collagen, which co-localized with significant production of glycosaminoglycans.
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- D'Andrea, S. D., et al.
(author)
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Understanding global secondary organic aerosol amount and size-resolved condensational behavior
- 2013
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In: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 13:22, s. 11519-11534
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Journal article (peer-reviewed)abstract
- Recent research has shown that secondary organic aerosols (SOA) are major contributors to ultrafine particle growth to climatically relevant sizes, increasing global cloud condensation nuclei (CCN) concentrations within the continental boundary layer (BL). However, there are three recent developments regarding the condensation of SOA that lead to uncertainties in the contribution of SOA to particle growth and CCN concentrations: (1) while many global models contain only biogenic sources of SOA (with annual production rates generally 10-30 Tg yr(-1)), recent studies have shown that an additional source of SOA around 100 Tg yr(-1) correlated with anthropogenic carbon monoxide (CO) emissions may be required to match measurements. (2) Many models treat SOA solely as semi-volatile, which leads to condensation of SOA proportional to the aerosol mass distribution; however, recent closure studies with field measurements show nucleation mode growth can be captured only if it is assumed that a significant fraction of SOA condenses proportional to the Fuchs-corrected aerosol surface area. This suggests a very low volatility of the condensing vapors. (3) Other recent studies of particle growth show that SOA con-densation at sizes smaller than 10 nm and that size-dependent growth rate parameterizations (GRP) are needed to match measurements. We explore the significance of these three findings using GEOS-Chem-TOMAS global aerosol microphysics model and observations of aerosol size distributions around the globe. The change in the concentration of particles of size D-p > 40 nm (N40) within the BL assuming surface-area condensation compared to mass-distribution net condensation yielded a global increase of 11% but exceeded 100% in biogenically active regions. The percent change in N40 within the BL with the inclusion of the additional 100 Tg SOAyr(-1) compared to the base simulation solely with biogenic SOA emissions (19 Tg yr-1) both using surface area condensation yielded a global increase of 13.7 %, but exceeded 50% in regions with large CO emissions. The inclusion of two different GRPs in the additional-SOA case both yielded a global increase in N40 of < 1 %, however exceeded 5% in some locations in the most extreme case. All of the model simulations were compared to measured data obtained from diverse locations around the globe and the results confirmed a decrease in the model-measurement bias and improved slope for comparing modeled to measured CCN number concentration when non-volatile SOA was assumed and the extra SOA was included.
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