Matrix rigidity regulates spatiotemporal dynamics of Cdc42 activity and vacuole formation kinetics of endothelial colony forming cells

Recent evidence has shown that endothelial colony forming cells (ECFCs) may serve as a cell therapy for improving blood vessel formation in subjects with vascular injury, largely due to their robust vasculogenic potential. The Rho family GTPase Cdc42 is known to play a primary role in this vasculogenesis process, but little is known about how extracellular matrix (ECM) rigidity affects Cdc42 activity during the process. In this study, we addressed two questions: Does matrix rigidity affect Cdc42 activity in ECFC undergoing early vacuole formation? How is the spatiotemporal activation of Cdc42 related to ECFC vacuole formation? A fluorescence resonance energy transfer (FRET)-based Cdc42 biosensor was used to examine the effects of the rigidity of three-dimensional (3D) collagen matrices on spatiotemporal activity of Cdc42 in ECFCs. Collagen matrix stiffness was modulated by varying the collagen concentration and therefore fibril density. The results showed that soft (150 Pa) matrices induced an increased level of Cdc42 activity compared to stiff (1 kPa) matrices. Time-course imaging and colocalization analysis of Cdc42 activity and vacuole formation revealed that Cdc42 activity was colocalized to the periphery of cytoplasmic vacuoles. Moreover, soft matrices generated faster and larger vacuoles than stiff matrices. The matrix-driven vacuole formation was enhanced by a constitutively active Cdc42 mutant, but significantly inhibited by a dominant-negative Cdc42 mutant. Collectively, the results suggest that matrix rigidity is a strong regulator of Cdc42 activity and vacuole formation kinetics, and that enhanced activity of Cdc42 is an important step in early vacuole formation in ECFCs

Controlled access to a heterometallic N-heterocyclic carbene helicate

10.1039/c4cc08270bChemical Communications5171248-125

Determining the Electron-Donating Properties of Bidentate Ligands by ¹³C NMR Spectroscopy

A series of 15 mononuclear complexes [PdBr­(^<i>i</i>Pr₂-bimy)­(L₂)]­PF₆ (<b>1</b>–<b>15</b>) (^<i>i</i>Pr₂-bimy = 1,3-diisopropylbenzimidazolin-2-ylidene, L₂ = aromatic 1,2-diimines, diazabutadienes, or methylene-, ethylene- and propylene-bridged di-N-heterocyclic carbenes) and two dicarbene-bridged, dinuclear complexes [Pd₂Br₄(^<i>i</i>Pr₂-bimy)₂(diNHC)] (<b>16</b> and <b>17</b>) were synthesized and characterized by multinuclear NMR spectroscopy, electrospray ionization mass spectrometry, and in some cases X-ray diffraction analysis. The influence of the 15 bidentate ligands L₂ on the ¹³C_carbene signals of the ^<i>i</i>Pr₂-bimy reporter ligand in the chelate complexes was studied, on the basis of which a facile methodology for the donor strength determination of bidentate ligands was developed

Structural Entropy of the Stochastic Block Models

With the rapid expansion of graphs and networks and the growing magnitude of data from all areas of science, effective treatment and compression schemes of context-dependent data is extremely desirable. A particularly interesting direction is to compress the data while keeping the “structural information” only and ignoring the concrete labelings. Under this direction, Choi and Szpankowski introduced the structures (unlabeled graphs) which allowed them to compute the structural entropy of the Erdős–Rényi random graph model. Moreover, they also provided an asymptotically optimal compression algorithm that (asymptotically) achieves this entropy limit and runs in expectation in linear time. In this paper, we consider the stochastic block models with an arbitrary number of parts. Indeed, we define a partitioned structural entropy for stochastic block models, which generalizes the structural entropy for unlabeled graphs and encodes the partition information as well. We then compute the partitioned structural entropy of the stochastic block models, and provide a compression scheme that asymptotically achieves this entropy limit

Prediction method of favorable positions of transporting oil and gas capacity configuration in different periods of faults

The development and evaluation of the transport capacity of oil and gas determine the location of the associated fractures based on the analysis of its ability to transport oil and gas and finding favorable locations in different periods of the faults. This paper also explored the distribution of oil and gas in different positions near the lower generation and upper reservoir faults in the petroliferous basin, while locations of the faults’ convex ridges with stronger oil and gas transporting ability are also determined and evaluated. A set of prediction methods in determining favorable locations for oil and gas transport capacity configured in different periods of fault are established and applied in different periods of the F3 fault in the Daliuquan area, Langgu Sag, Jizhong Depression, Bohai Bay Basin. The results of these two evaluations indicate that the development position of associated fractures of the F3 fault with strong oil and gas transport capacity was distributed primarily in the eastern part of the area. Sections of the convex ridge with stronger oil and gas transport capacity, on the other hand, are mainly distributed in the western, middle, and eastern faults. The favorable location of transporting oil and gas ability configuration of the F3 fault in different periods is distributed mainly in the east of the F3 fault, where oil and gas generated by the source rock of the Sha 4 Member (Es4) migrate and accumulate to the middle and lower sections of the Sha 3 Member (Es31−2) through the developmental position of associated fractures and convex ridges

A Novel Bone Gelatin Prepared by Enzymatic Catalysis with High Crosslinking Activity of MTGase for Gelatinization Properties of Minced Pork

A novel gelatin prepared by enzymatic catalysis (type-E bone gelatin) was developed in our group. In this study, the high crosslinking activity of type-E bone gelatin with microbial transglutaminase (MTGase) was found and further used for the gelatinization properties of minced pork. The results showed that the contents of lysine and glutamine in type-E bone gelatin were higher than that of traditional gelatin prepared by acid (type-A gelatin) and alkali (type-B gelatin) methods, which are as action sites for MTGase. The crosslinking degree (79%) of type-E was approximately 4.9 times that of type-A and 5.6 times that of type-B at 1.44 U/g MTGase. Moreover, the type-E gel showed thermal irreversibility when the MTGase concentration was higher than 0.90 U/g due to high crosslinking activity. For minced pork gel, the water-holding capacity and texture properties of minced pork modified with type-E bone gelatin crosslinked by MTGase were improved and cooking loss was significantly reduced

Template-Directed Synthesis of Palladium(II) Sulfonate-NHC Complexes and Catalytic Studies in Aqueous Mizoroki–Heck Reactions

Oxidation of easily accessible thiolato-functionalized dinuclear Pd­(II) NHC complexes <b>1</b>–<b>3</b> by Oxone gave rise to sulfonate-NHC complexes <b>4</b>–<b>6</b>. This represents the first template-directed approach to NHC complexes bearing sulfonate functions, where the sulfur atoms undergo a six-electron oxidation, changing their oxidation states from −II to +IV. The catalytic activities of water-soluble <b>4</b>–<b>6</b> were also tested in aqueous Mizoroki–Heck reactions

Template-Directed Synthesis of Palladium(II) Sulfonate-NHC Complexes and Catalytic Studies in Aqueous Mizoroki–Heck Reactions

Oxidation of easily accessible thiolato-functionalized dinuclear Pd­(II) NHC complexes <b>1</b>–<b>3</b> by Oxone gave rise to sulfonate-NHC complexes <b>4</b>–<b>6</b>. This represents the first template-directed approach to NHC complexes bearing sulfonate functions, where the sulfur atoms undergo a six-electron oxidation, changing their oxidation states from −II to +IV. The catalytic activities of water-soluble <b>4</b>–<b>6</b> were also tested in aqueous Mizoroki–Heck reactions

Subcellular domain-dependent molecular hierarchy of SFK and FAK in mechanotransduction and cytokine signaling

Focal adhesion kinase (FAK) and Src family kinases (SFK) are known to play critical roles in mechanotransduction and other crucial cell functions. Recent reports indicate that they reside in different microdomains of the plasma membrane. However, little is known about their subcellular domain-dependent roles and responses to extracellular stimuli. Here, we employed fluorescence resonance energy transfer (FRET)-based biosensors in conjunction with collagen-coupled agarose gels to detect subcellular activities of SFK and FAK in three-dimensional (3D) settings. We observed that SFK and FAK in the lipid rafts and nonrafts are differently regulated by fluid flow and pro-inflammatory cytokines. Inhibition of FAK in the lipid rafts blocked SFK response to fluid flow, while inhibition of SFK in the non-rafts blocked FAK activation by the cytokines. Ex-vivo FRET imaging of mouse cartilage explants showed that intermediate level of interstitial fluid flow selectively decreased cytokine-induced SFK/FAK activation. These findings suggest that SFK and FAK exert distinctive molecular hierarchy depending on their subcellular location and extracellular stimuli

Bis(functionalized NHC) Palladium(II) Complexes via a Postmodification Approach

A series of 20 bis­(functionalized NHC) Pd­(II) complexes have been conveniently synthesized through postmodification reactions of the common parent NHC complexes <i>trans</i>-[PdBr₂(C₃Br-bimy)₂] (<b>1a)</b> and <i>trans</i>-[PdBr₂(C₃Br-imy)₂] (<b>1b</b>) (C₃Br-bimy = 1-benzyl-3-(3-bromopropyl)­benzimidazolin-2-ylidene and C₃Br-imy = 1-benzyl-3-(3-bromopropyl)­imidazolin-2-ylidene) with an <i>N</i>-C₃Br tether. Depending on the nature of the nucleophiles added, competing bromido ligand displacements also occurred. In comparison to the conventional access to functionalized NHC complexes, which involves metalation of individually prefunctionalized azolium salts, this highly modular method proves more effective in cost and time savings. The tetraalkylammonium-functionalized complex <i>trans</i>-[PdBr₂(C₃NEt₃-bimy)₂]­Br₂ (<b>14</b>) as a product of the second-generation postmodification of complex <b>1a</b> was also tested for its catalytic activity in Mizoroki–Heck coupling reactions to study and model the effect of a catalytic amount of ammonium salt additive in Pd-catalyzed C–C coupling reactions. The ammonium functionalities in this complex exhibit a positive effect on the catalysis in comparison to its parent complexes