Mechanotransduction of mitochondrial AMPK and its distinct role in flow-induced breast cancer cell migration

The biophysical microenvironment of the tumor site has significant impact on breast cancer progression and metastasis. The importance of altered mechanotransduction in cancerous tissue has been documented, yet its role in the regulation of cellular metabolism and the potential link between cellular energy and cell migration remain poorly understood. In this study, we investigated the role of mechanotransduction in AMP-activated protein kinase (AMPK) activation in breast cancer cells in response to interstitial fluid flow (IFF). Additionally, we explored the involvement of AMPK in breast cancer cell migration. IFF was applied to the 3D cell-matrix construct. The subcellular signaling activity of Src, FAK, and AMPK was visualized in real-time using fluorescent resonance energy transfer (FRET). We observed that breast cancer cells (MDA-MB-231) are more sensitive to IFF than normal epithelial cells (MCF-10A). AMPK was activated at the mitochondria of MDA-MB-231 cells by IFF, but not in other subcellular compartments (i.e., cytosol, plasma membrane, and nucleus). The inhibition of FAK or Src abolished flow-induced AMPK activation in the mitochondria of MDA-MB-231 cells. We also observed that global AMPK activation reduced MDA-MB-231 cell migration. Interestingly, specific AMPK inhibition in the mitochondria reduced cell migration and blocked flow-induced cell migration. Our results suggest the linkage of FAK/Src and mitochondria-specific AMPK in mechanotransduction and the differential role of AMPK in breast cancer cell migration depending on its subcellular compartment-specific activation

Tetra­ethyl­ammonium bicarbonate trihydrate

In the title compound, C8H20N+·CHO3 −·3H2O, the bicarbon­ate anion, which has a small mean deviation from the plane of 0.0014 Å, fully utilises its three O and one H atom to form various O—H⋯O hydrogen bonds with the three water mol­ecules in the asymmetric unit, generating a hydrogen-bonded layer, which extends along (10). The tetra­ethyl­ammonium cations, as the guest species, are accommodated between every two neighboring layers, constructing a sandwich-like structure with an inter­layer distance of 7.28 Å

Organizational Network Evolution and Governance Strategies in Megaprojects

The organization is the key factor for megaprojects in which thousands of connections and relations intertwine and influence the project performance. However, organizational evolution in megaprojects has not been fully studied. This study investigates the evolution of the organizational network of a megaproject in China using social network analysis (SNA), and then proposes corresponding governance strategies. The result shows that megaproject organizations evolve towards more connected networks but are differentiated for various investors. For government invested projects, the organizational network is well connected, cooperative, yet unstable and require strategic long-term governance policies; for private invested projects, the network is stable, but collaboration among participants is low, which indicates a need to establish collaborative governance structures. The result complements the organizational evolution theory for megaprojects and offers effective strategies for governing megaproject organizations. This study also helps practitioners better understand the nature and characteristics of megaproject organizations.

A novel carboxyl-terminal protease derived from <em>Paenibacillus lautus</em> CHN26 exhibiting high activities at multiple sites of substrates

BACKGROUND: Carboxyl-terminal protease (CtpA) plays essential functions in posttranslational protein processing in prokaryotic and eukaryotic cells. To date, only a few bacterial ctpA genes have been characterized. Here we cloned and characterized a novel CtpA. The encoding gene, ctpAp (ctpA of Paenibacillus lautus), was derived from P. lautus CHN26, a Gram-positive bacterium isolated by functional screening. Recombinant protein was obtained from protein over-expression in Escherichia coli and the biochemical properties of the enzyme were investigated. RESULTS: Screening of environmental sediment samples with a skim milk-containing medium led to the isolation of a P. lautus CHN26 strain that exhibited a high proteolytic activity. A gene encoding a carboxyl-terminal protease (ctpAp) was cloned from the isolate and characterized. The deduced mature protein contains 466 aa with a calculated molecular mass of 51.94 kDa, displaying 29-38% amino acid sequence identity to characterized bacterial CtpA enzymes. CtpAp contains an unusual catalytic dyad (Ser(309)-Lys(334)) and a PDZ substrate-binding motif, characteristic for carboxyl-terminal proteases. CtpAp was expressed as a recombinant protein and characterized. The purified enzyme showed an endopeptidase activity, which effectively cleaved α S1- and β- casein substrates at carboxyl-terminus as well as at multiple internal sites. Furthermore, CtpAp exhibited a high activity at room temperature and strong tolerance to conventional protease inhibitors, demonstrating that CtpAp is a novel endopeptidase. CONCLUSIONS: Our work on CtpA represents the first investigation of a member of Family II CtpA enzymes. The gene was derived from a newly isolated P. lautus CHN26 strain exhibiting a high protease activity in the skim milk assay. We have demonstrated that CtpAp is a novel endopeptidase with distinct cleavage specificities, showing a strong potential in biotechnology and industry applications

Fabrication of porous Al2O3-based ceramics using combustion synthesized powders

Porous Al2O3-based ceramics were fabricated from powders synthesized via a solution combustion process using starch and urea as fuels. Effects of the relative fuel-to-oxidant ratio (φe = 1.4, 1.6, 1.8 and 2.0, respectively) on open porosity, pore size distribution and flexural strength of the as-prepared porous Al2O3-based ceramics were investigated. Experimental results revealed that the densification ability of the as-synthesized powders increased significantly as φe increased, and open porosity, pore size distribution and flexural strength of the porous ceramics exhibited remarkable dependence on the densification ability of the powders instead of the weight fraction of the charred organic residuals in the powders. SEM micrographs disclosed that the porous ceramics from the precursors with φe = 1.8 or 2.0 exhibited significantly homogenous microstructures including pore size and pore distribution

Tetra­ethyl­ammonium 4-hy­droxy­benzoate monohydrate

In the title compound, C8H20N+·C7H5O3 −·H2O, the carboxyl­ate group is slightly out of the plane of the parent benzene ring, the C—C—C—O torsion angles being 2.3 (2) and 2.0 (2)°. The carboxyl­ate group and the hy­droxy group form O—H⋯O hydrogen bonds, generating a head-to-tail chain along the b axis. Neighbouring hydrogen-bonded chains are linked by the water mol­ecule, generating two independent O—H⋯O donor hydrogen bonds. The carboxyl­ate group thus constructs a hydrogen-bonded host layer parallel to (10). The tetra­ethyl­ammonium cation is contained between these layers, forming a sandwich-like structure with an approximate inter­layer distance of 10.03 Å