Cancer cell migration during metastasis is mediated by a highly polarized cytoskeleton. MARK2 and its invertebrate homolog Par1B are kinases that regulate the microtubule cytoskeleton to mediate ...polarization of neurons in mammals and embryos in invertebrates. However, the role of MARK2 in cancer cell migration is unclear. Using osteosarcoma cells, we found that in addition to its known localizations on microtubules and the plasma membrane, MARK2 also associates with the actomyosin cytoskeleton and focal adhesions. Cells depleted of MARK proteins demonstrated that MARK2 promotes phosphorylation of both myosin II and the myosin phosphatase targeting subunit MYPT1 to synergistically drive myosin II contractility and stress fiber formation in cells. Studies with isolated proteins showed that MARK2 directly phosphorylates myosin II regulatory light chain, while its effects on MYPT1 phosphorylation are indirect. Using a mutant lacking the membrane-binding domain, we found that membrane association is required for focal adhesion targeting of MARK2, where it specifically enhances cell protrusion by promoting FAK phosphorylation and formation of focal adhesions oriented in the direction of migration to mediate directionally persistent cell motility. Together, our results define MARK2 as a master regulator of the actomyosin and microtubule cytoskeletal systems and focal adhesions to mediate directional cancer cell migration.
•MARK2 associates with the actomyosin cytoskeleton•MARK2 promotes phosphorylation of MRLC and MYPT1 to drive contractility•MARK2 associates with focal adhesions via its membrane-binding domain•MARK2 promotes FAK activation and focal adhesion formation and orientation
Pasapera et al. show that the microtubule regulatory and polarity protein MARK2 associates with actomyosin and promotes phosphorylation of myosin II regulatory light chain and MYPT1 to drive contractility. MARK2 also associates with focal adhesions (FAs) and promotes FAK activation and FA formation/orientation to drive directional cell migration.
Common methods for fabrication of polyelectrolyte microcapsules rely on a multi-step process. We propose a single-step approach to generate polyelectrolyte microcapsules with 1-2 μm shells based on ...polyelectrolyte complexation across a water/oil droplet interface and study the effect of parameters controlling the polyelectrolyte complexation on shell thickness.
In eukaryotic cells, the nuclear envelope separates the genomic DNA from the cytoplasmic space and regulates protein trafficking between the two compartments. This barrier is only transiently ...dissolved during mitosis. Here, we found that it also opened at high frequency in migrating mammalian cells during interphase, which allowed nuclear proteins to leak out and cytoplasmic proteins to leak in. This transient opening was caused by nuclear deformation and was rapidly repaired in an ESCRT (endosomal sorting complexes required for transport)–dependent manner. DNA double-strand breaks coincided with nuclear envelope opening events. As a consequence, survival of cells migrating through confining environments depended on efficient nuclear envelope and DNA repair machineries. Nuclear envelope opening in migrating leukocytes could have potentially important consequences for normal and pathological immune responses.
Weather index-based crop insurance is increasingly becoming important as a risk mitigation strategy that farmers may use to mitigate adverse climate shocks and natural disasters encountered during ...farming. While Europe, North America, and Asia account for 20.1%, 55%, and 19.5% of the total agricultural insurance premium worldwide, respectively, Africa accounts for only 0.5% of the world insurance industry. One of the key reasons advanced against the low index insurance participation rate in Africa is the failure to involve farm households at the initial conceptualization and design of pilot initiatives. Therefore, the main purpose of this paper is to design an improved participatory methodology that could help elicit information on the value placed by farm households in Southwestern Burkina Faso on a new weather index-based crop insurance management initiative. A key concept in the improved participatory methodology is that of the willingness to pay (WTP) of farm households for the scheme. Knowledge of the maximum amount that farmers are willing to pay for the scheme can help insurance policy providers and public policy makers to design and put in place measures that sustain index insurance schemes in a developing country context and improve welfare among participating farmers.
Abstract Most methods define a limited number of “target” lesions to be measured and other “non-target” lesions to be evaluated qualitatively. RECIST criteria are the most widely used although other ...criteria have been proposed that are derived from them based on size alone, or size and attenuation. Modified RECIST (mRECIST) criteria only concern hepatocellular carcinoma and only take into account the viable portion (enhanced after injection during the arterial phase). Cheson criteria are more complex as target lesions are defined differently depending on the organ (lymph nodes, liver or spleen, other organs), and involve both CT and PET scans, as well as the clinical examination and bone marrow biopsy.
Background: In metastatic renal cell carcinoma (mRCC), antiangiogenic treatments rarely achieve a reduction of -30% in the sum of longest diameters (SLD) of target lesions required by RECIST for an ...‘objective response’, although they objectively improve progression-free survival (PFS). We sought to determine a threshold for the computed tomography evaluation of these patients’ best reflecting patient outcome.
Patients and methods: In 334 mRCC patients treated with sunitinib, we tested thresholds from -45% to +10%. We classified patients as ‘responders’ when the best relative variation of the sum of longest diameters (ΔSLD) reached the tested threshold and as ‘nonresponders’ otherwise. For each tested threshold, the median PFS of the two groups were compared. Receiver operating characteristic (ROC) analysis was also carried out among the 103 patients that progressed during follow-up. Finally, the ‘optimal’ threshold was retested on an independent cohort of 39 patients.
Results: The ΔSLD threshold of -10% gave the most significant difference. It divided patients into 256 responders and 78 nonresponders (median PFS 11.1 and 5.6 months). The same -10% threshold was found using the ROC analysis. Results were confirmed on the external validation cohort.
Conclusion: A variation of -10% in the SLD accurately and rapidly identifies mRCC patients benefiting from sunitinib.
Objectives
To evaluate whether changes in BOLD signal intensities following hyperoxygenation are related to intrauterine growth restriction (IUGR) in a rat model.
Methods
IUGR was induced in pregnant ...rats by ligating the left vascular uterine pedicle at day 16 of gestation. BOLD MR imaging using a balanced steady-state free-precession (balanced-SSFP) sequence on a 1.5-T system was performed on day 19. Signal intensities (SI) before and after maternal hyperoxygenation were compared in the maternal liver and in control and growth-restricted foetoplacental units (FPUs).
Results
Maternal hyperoxygenation resulted in a significant increase in SI in all regions of interest (
P
< 0.05) in the 18 rats. In the control group, the SI (mean ± SD) increased by 21 % ± 15 in placentas (
n
= 74) and 13 % ± 8.5 in foetuses (
n
= 53). In the IUGR group, the increase was significantly lower: 6.5 % ± 4 in placentas (
n
= 36) and 7 % ± 5.5 in foetuses (
n
= 34) (
P
< 0.05).
Conclusion
BOLD MRI allows non-invasive assessment of the foetoplacental response to maternal hyperoxygenation in the rat and demonstrates its alteration in an IUGR model. This imaging method may provide a useful adjunct for the early diagnosis, evaluation, and management of human IUGR.
Key Points
•
Intra-uterine growth restriction is an important cause of perinatal morbidity and mortality.
•
Blood oxygen level-dependent MRI non-invasively assesses foetoplacental response to maternal hyperoxygenation.
•
In the rat, foetoplacental response to maternal hyperoxygenation is altered in IUGR.
•
Functional MRI may help to assess human IUGR.
Penetratin is a cell penetrating peptide (CPP) that can enter cells by direct translocation through the plasma membrane. The molecular mechanism of this translocation still remains poorly understood. ...Here we provide insights on this mechanism by studying the direct translocation of the peptide across model membranes based on Droplet Interface Bilayers (DIBs), which are bilayers at the interface between two adhering aqueous-in-oil droplets. We first showed with symmetric bilayers made of a mix of 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-(1′-rac-glycerol) (POPG) and 1,2-dioleoyl-sn-glycero-3-phosphocholine (POPC) that the translocation of penetratin required the presence of at least 40% of POPG on both leaflets. Interestingly when replacing POPG with another anionic lipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-l-serine (POPS), translocation was inefficient. To elucidate the lipid partners required at each step of the CPP translocation process, we then investigated the crossing of asymmetric bilayers. We found that POPG on the proximal leaflet and POPS on the distal leaflet allowed penetratin translocation. Translocation was not observed when POPS was on the proximal leaflet and POPG on the distal leaflet or if POPS on the distal leaflet was replaced with POPC. These observations led us to propose a three-step translocation mechanism: (i) peptide recruitment by anionic lipids, (ii) formation of a transient peptide-lipid structure leading to the initiation of translocation which required specifically POPG on the proximal leaflet, (iii) termination of the translocation process favored by a driving force provided by anionic lipids in the distal leaflet.
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•Asymmetric droplet interface bilayers are used to assess penetratin translocation•Penetratin translocation is favored by POPG lipids•POPG is required on the proximal leaflet to initiate translocation•We determine which lipids are necessary for each step of the translocation
Please cite this paper as: Deloison B, Siauve N, Aimot S, Balvay D, Thiam R, Cuenod C, Ville Y, Clement O, Salomon L. SPIO‐enhanced magnetic resonance imaging study of placental perfusion in a rat ...model of intrauterine growth restriction. BJOG 2012;119:626–633.
Objective To assess placental perfusion with magnetic resonance imaging (MRI) and superparamagnetic iron oxide (SPIO) in a rat model of intrauterine growth restriction (IUGR).
Design Experimental animal study.
Setting The study complied with US National Institutes of Health recommendations for animal care.
Population Thirty‐two rats at day 16 of gestation underwent surgical ligation of the left uterine vessel to induce IUGR.
Methods Eighteen rats were examined by MRI 3 days later, after bolus injection of ferucarbotran.
Main outcome measure Signal intensities were measured in the maternal left ventricle and in the placentas of the two horns. Quantitative microcirculation parameters were calculated and compared between the placentas of the two horns.
Results Fifty‐four kinetic curves of placental perfusion were obtained in 11 rats. The mean placental blood flow was significantly lower in the ligated horns than in the normal horns (108.1 versus 159.4 ml/minute/100 ml, p = 0.0004). The mean fractional volume of the maternal vascular placental compartment did not differ significantly between the pathological (42.8%) and normal placentas (39.2%).
Conclusions Placental perfusion, including changes during experimental IUGR, can be measured in rats by using MRI with SPIO. These findings could have implications for human studies of placental microcirculation and for the management of disorders related to placental dysfunction.
Water-in-oil emulsion drops are formed and stabilized with phospholipids which can adhere and form a bilayer. Using microfluidics, adhesive drop pairs are then trapped and submitted to an ac electric ...field. We observe three distinct states as a function of the adhesion energy and the electric field intensity. The pair can be either stable, though slightly deformed, or unzip and separate, or coalesce. The frontiers between the different states directly reflect vesicle detachment forces and electroporation theories. The experimental approach that we propose for probing liquid interface wetting between monolayers allows us to finely tuned the tension in the bilayer and gives access to bilayer unzipping.
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