scholarly journals Symmetry Breaking and Emergence of Directional Flows in Minimal Actomyosin Cortices

Cells ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 1432 ◽  
Author(s):  
Sven K. Vogel ◽  
Christian Wölfer ◽  
Diego A. Ramirez-Diaz ◽  
Robert J. Flassig ◽  
Kai Sundmacher ◽  
...  
Keyword(s):  
Symmetry Breaking ◽  
Large Scale ◽  
Scale Up ◽  
Feedback Mechanism ◽  
Model Systems ◽  
Spatial Confinement ◽  
Emulsion Droplets ◽  
Directional Motion ◽  
Spontaneous Contractions

Cortical actomyosin flows, among other mechanisms, scale up spontaneous symmetry breaking and thus play pivotal roles in cell differentiation, division, and motility. According to many model systems, myosin motor-induced local contractions of initially isotropic actomyosin cortices are nucleation points for generating cortical flows. However, the positive feedback mechanisms by which spontaneous contractions can be amplified towards large-scale directed flows remain mostly speculative. To investigate such a process on spherical surfaces, we reconstituted and confined initially isotropic minimal actomyosin cortices to the interfaces of emulsion droplets. The presence of ATP leads to myosin-induced local contractions that self-organize and amplify into directed large-scale actomyosin flows. By combining our experiments with theory, we found that the feedback mechanism leading to a coordinated directional motion of actomyosin clusters can be described as asymmetric cluster vibrations, caused by intrinsic non-isotropic ATP consumption with spatial confinement. We identified fingerprints of vibrational states as the basis of directed motions by tracking individual actomyosin clusters. These vibrations may represent a generic key driver of directed actomyosin flows under spatial confinement in vitro and in living systems.

scholarly journals Symmetry Breaking and Emergence of Directional Flows in Minimal Actomyosin Cortices

2020 ◽  
Author(s):  
Sven K. Vogel ◽  
Christian Wölfer ◽  
Diego A. Ramirez-Diaz ◽  
Robert J. Flassig ◽  
Kai Sundmacher ◽  
...  
Keyword(s):  
Symmetry Breaking ◽  
Large Scale ◽  
Scale Up ◽  
Feedback Mechanism ◽  
Model Systems ◽  
Spatial Confinement ◽  
Emulsion Droplets ◽  
Directional Motion ◽  
Spontaneous Contractions

Cortical actomyosin flows, among other mechanisms, scale up spontaneous symmetry breaking and thus play pivotal roles in cell differentiation, division, and motility. According to many model systems, myosin motor-induced local contractions of initially isotropic actomyosin cortices are nucleation points for generating cortical flows. However, the positive feedback mechanisms by which spontaneous contractions can be amplified towards large-scale directed flows remain mostly speculative. To investigate such a process on spherical surfaces, we reconstituted and confined initially isotropic minimal actomyosin cortices to the interfaces of emulsion droplets. The presence of ATP leads to myosin-induced local contractions that self-organize and amplify into directed, large-scale actomyosin flows. By combining our experiments with theory, we found that the feedback mechanism leading to a coordinated, directional motion of actomyosin clusters can be described as asymmetric cluster vibrations, caused by intrinsic non-isotropic ATP consumption, in conjunction with spatial confinement. By tracking individual actomyosin clusters, we identified fingerprints of vibrational states as the basis of directed motions. These vibrations may represent a generic key driver of directed actomyosin flows under spatial confinement in vitro and in living systems.

scholarly journals Emergence of Directional Actomyosin Flows from Active Matter Vibrations

2018 ◽  
Author(s):  
Sven K. Vogel ◽  
Christian Wölfer ◽  
Diego A. Ramirez-Diaz ◽  
Robert J. Flassig ◽  
Kai Sundmacher ◽  
...  
Keyword(s):  
Large Scale ◽  
Model Systems ◽  
Living Systems ◽  
Vibrational States ◽  
Spatial Confinement ◽  
Emulsion Droplets ◽  
Directional Motion ◽  
Key Driver ◽  
Local Motor

AbstractCortical actomyosin flows play pivotal roles in cell motility, cell division and animal morphogenesis. According to many model systems, myosin motor induced local contractions are key for generating cortical flows. However, the original mechanism how large-scale directed flows emerge from local motor activity in an apparently isotropic cortex is unknown. We reconstituted and confined minimal actomyosin cortices to the interfaces of emulsion droplets. The presence of ATP leads to myosin-induced cortical contractions that self-organize into directed flow-like actomyosin motions. By combining our experiments with theory, we found that the large-scale directional motion of actomyosin clusters emerges from individual asymmetric cluster vibrations, caused by intrinsic non-isotropic ATP consumption, in conjunction with spherical confinement. By tracking individual actomyosin clusters, we identified fingerprints of vibrational states as the basis of directed motions. These vibrations may represent a generic key driver of directed actomyosin flows under spatial confinement in vitro and in living systems.

scholarly journals Unbiased in vivo preclinical evaluation of anticancer drugs identifies effective therapy for the treatment of pancreatic adenocarcinoma

2020 ◽  
Vol 117 (48) ◽  
pp. 30670-30678
Author(s):  
Olivera Grbovic-Huezo ◽  
Kenneth L. Pitter ◽  
Nicolas Lecomte ◽  
Joseph Saglimbeni ◽  
Gokce Askan ◽  
...  
Keyword(s):  
Large Scale ◽  
Single Agent ◽  
Model Systems ◽  
Ductal Adenocarcinoma ◽  
In Vivo Model ◽  
Cancer Therapies ◽  
Hsp90 Inhibition ◽  
Dismal Prognosis

Pancreatic ductal adenocarcinoma (PDAC) is typically diagnosed at an advanced stage, which limits surgical options and portends a dismal prognosis. Current oncologic PDAC therapies confer marginal benefit and, thus, a significant unmet clinical need exists for new therapeutic strategies. To identify effective PDAC therapies, we leveraged a syngeneic orthotopic PDAC transplant mouse model to perform a large-scale, in vivo screen of 16 single-agent and 41 two-drug targeted therapy combinations in mice. Among 57 drug conditions screened, combined inhibition of heat shock protein (Hsp)-90 and MEK was found to produce robust suppression of tumor growth, leading to an 80% increase in the survival of PDAC-bearing mice with no significant toxicity. Mechanistically, we observed that single-agent MEK inhibition led to compensatory activation of resistance pathways, including components of the PI3K/AKT/mTOR signaling axis, which was overcome with the addition of HSP90 inhibition. The combination of HSP90(i) + MEK(i) was also active in vitro in established human PDAC cell lines and in vivo in patient-derived organoid PDAC transplant models. These findings encourage the clinical development of HSP90(i) + MEK(i) combination therapy and highlight the power of clinically relevant in vivo model systems for identifying cancer therapies.

Preparative chromatographic purification of cyclosporine metabolites

1993 ◽  
Vol 39 (3) ◽  
pp. 457-466 ◽  
Author(s):  
C A Brooks ◽  
S M Cramer ◽  
T G Rosano
Keyword(s):  
Animal Studies ◽  
Large Scale ◽  
Scale Up ◽  
Reversed Phase ◽  
Preparative Scale ◽  
Primary Metabolites ◽  
Rapid Processing ◽  
Adsorption Desorption ◽  
Elution Chromatography

Abstract Polar and primary metabolites of cyclosporin A (CsA) have successfully been isolated by a novel separation protocol. An efficient, easy-to-scale-up chromatographic adsorption/desorption operation recovers polar and primary CsA metabolite pools from large volumes of urine; purified CsA metabolites are subsequently obtained by high-resolution preparative elution chromatography of the semipurified metabolite pools. Separations performed on a semipreparative scale [with a 250 x 9.4 mm (i.d.) reversed-phase HPLC column] yielded microgram quantities of CsA metabolites at > 97% purity, as determined by fast atom bombardment mass spectrometry. These separations also yielded two previously unreported CsA metabolites, similar to AM1A but with an additional hydroxylation. The yield of metabolites was increased to several milligrams by performing the separations with a preparative-scale [250 x 21.2 mm (i.d.)] reversed-phase column. The production rate of purified primary CsA metabolites was greatly increased by performing the separation with the preparative-scale column under conditions of severe mass overloading. In a single chromatographic run, we successfully isolated 11.0 and 5.0 mg of AM1 and AM1c, respectively, at a purity of > 97%. As expected, this increase in the yield of purified metabolites was accompanied by a decrease in the overall recovery. This separation scheme enables the rapid processing of large volumes of urine for isolation of the milligram quantities of CsA metabolites necessary to assess their biological activity. The procedure is applicable to small- or large-scale metabolite isolation and provides a ready source of purified metabolites for in vitro and whole-animal studies.

Detection of risk of cancer to man

1979 ◽  
Vol 205 (1158) ◽  
pp. 111-120 ◽  
Keyword(s):  
Large Scale ◽  
Human Cancer ◽  
Environmental Pollutants ◽  
Model Systems ◽  
Fourth Power ◽  
Percentage Increase ◽  
Direct Estimate ◽  
Human Carcinogenesis ◽  
Risk Of Cancer

Epidemiology can pick out large-scale determinants of human cancer, such as smoking. Also, epidemiology can pick out carcinogens such as asbestos to which groups of perhaps a few hundred or a few thousand workers have been heavily exposed for decades. However, if highly exposed groups cannot be studied then epidemiology cannot recognize carcinogens which, although perhaps widely distributed, produce only a small percentage increase in particular cancers. Almost all of the environmental pollutants that can affect human cancer incidence will do so only to a very minor extent, at the levels to which we are currently exposed. For this reason, and also because it is often difficult to define an exposed and an unexposed group which do not differ in other ways as well, it will almost always be impossible to do anything epidemiologically except to set a very crude upper limit on their likely hazards. The only way, therefore, to get any direct estimate of these hazards is by laboratory studies of the effects of high doses on various model systems. For this and for other reasons, it would be highly desirable to have good laboratory models for human carcinogenesis. The characteristics required of satisfactory laboratory systems are reviewed, and it is argued that systematic errors may arise unless one studies epithelial cells from large, long-lived species under conditions of chronic, low-dose exposure to noxious test agents in conjunction with standard chronic doses of agents which may be synergistic with the test agents. (Carcinogenic mutagens may be synergistic with carcinogenic non-mutagens.) For reasons of expense and speed, such studies must be done in vitro . If such in-vitro systems can be developed, either by using tissue explants or cell cultures, an important criterion which they will have to satisfy to be trusted will be that under chronic exposure the rate of transformation should be proportional to something like the fourth power of exposure duration. This paper chiefly reviews the reasons for choosing these specifications for a trustworthy in-vitro model for human carcinogenesis.

scholarly journals A protein microarray-based in vitro transglutaminase assay platform for epitope mapping and peptide discovery

2021 ◽  
Author(s):  
Chen Liu
Keyword(s):  
Large Scale ◽  
Matrix Protein ◽  
Tissue Transglutaminase ◽  
Protein Microarray ◽  
Scale Up ◽  
Alpha Synuclein ◽  
Extracellular Matrix Protein ◽  
Dependent Manner ◽  
Scanning Method

Transglutaminases (TGs) are a family of crosslinking enzymes catalyzing the formation of intra- and inter-molecular glutamine-lysine isopeptide bonds in a calcium dependent manner. Activation of transglutaminases is pathogenically associated with severe human diseases including neurodegenerations, cardiovascular diseases, and autoimmune diseases. Although continuous efforts determining the enzymes substrate preference have been witnessed, a high-throughput assay platform with the omic efficiency is still missing for the global identification of substrate-specific TG modification sites. In this study we report a protein microarray-based in vitro TG assay platform for rapid and large-scale (up to 30000 reactions per chip) determination of the glutamine (Q)-bearing TG modification motifs. With this platform we identified the Q16 in superoxide dismutase 1 and Q109 in alpha-synuclein as the modification sites for tissue transglutaminase (TG2), the most ubiquitous member of the enzyme family. Of particular interest, we found a close match between the modification motif and published vaccine epitope sequence in alpha-synuclein. Our data collectively suggest the glutamine and its follow-up five residues on the C terminal compose a minimal determinant motif for TG2 modification. To screen for site-specific interfering peptides and assist gene editing-based protein engineering, we developed an onchip amino-acid scanning method for the optimization of TG2 modification motifs. Using this approach we optimized the TG2 modification motif QQIV in the extracellular matrix protein fibronectin and obtained 14 variants with significantly higher TG2 reactivity that might serve as the competitive inhibitor peptides and 1 with lower reactivity. We further confirmed the efficacy of this approach using 12-mer peptides, the longest ones that could be synthesized on the chip. Taken together, our synthetic assay platform will be able to not only deliver a precise epitope blueprint for personalized immunotherapy and vaccination but also provide proof-of-concept and directional studies for TG-based peptide discovery and protein design.

scholarly journals C-STEM: ENGINEERING NICHE-LIKE MICRO-COMPARTMENTS FOR OPTIMAL AND SCALE-INDEPENDENT EXPANSION OF HUMAN PLURIPOTENT STEM CELLS IN BIOREACTORS

2021 ◽  
Author(s):  
Philippe J.R. Cohen ◽  
Elisa Luquet ◽  
Justine Pletenka ◽  
Andrea Leonard ◽  
Elise Warter ◽  
...  
Keyword(s):  
Stem Cells ◽  
Pluripotent Stem Cells ◽  
Large Scale ◽  
Scale Up ◽  
Three Dimensional ◽  
Culture Conditions ◽  
Human Pluripotent Stem Cells ◽  
Cell Therapies ◽  
Cellular Source

Human pluripotent stem cells (hPSCs) have emerged as the most promising cellular source for cell therapies. To overcome scale up limitations of classical 2D culture systems, suspension cultures have been developed to meet the need of large-scale culture in regenerative medicine. Despite constant improvements, current protocols relying on the generation of micro-carriers or cell aggregates only achieve moderate amplification performance. Here, guided by reports showing that hPSCs can self-organize in vitro into cysts reminiscent of the epiblast stage in embryo development, we developed a physio-mimetic approach for hPSC culture. We engineered stem cell niche microenvironments inside microfluidics-assisted core-shell microcapsules. We demonstrate that lumenized three-dimensional colonies maximize viability and expansion rates while maintaining pluripotency. By optimizing capsule size and culture conditions, we scale-up this method to industrial scale stirred tank bioreactors and achieve an unprecedented hPSC amplification rate of 282-fold in 6.5 days.

PABPN1L assemble into “ring-like” aggregates in the cytoplasm of MII oocytes and is associated with female infertility†

2021 ◽  
Author(s):  
Ying Wang ◽  
Tianhao Feng ◽  
Mingcong Zhu ◽  
Xiaodan Shi ◽  
Zerui Wang ◽  
...  
Keyword(s):  
Embryonic Development ◽  
Mouse Model ◽  
Genetic Marker ◽  
Large Scale ◽  
Scale Up ◽  
Mrna Degradation ◽  
Female Infertility ◽  
Rna Seq ◽  
Maternal Mrna

Abstract Infertility affects 10% - 15% of families worldwide. However, the pathogenesis of female infertility caused by abnormal early embryonic development is not clear. A resent study showed that PABPN1L recruited BTG4 to mRNA 3′-poly(A) tails and was essential for maternal mRNA degradation. Here, we generated an PABPN1L-antibody and found “ring-like” PABPN1L aggregates in the cytoplasm of MII oocytes. PABPN1L-EGFP proteins spontaneously formed“ring-like” aggregates in vitro. This phenomenon is similar with CCR4–NOT catalytic subunit, CNOT7, when it starts deadenylation process in vitro. We constructed two mouse model (Pabpn1l  −/− and Pabpn1l  tm1a/tm1a) simulating the intron1-exon2 abnormality of human PABPN1L and found that the female was sterile and the male was fertile. Using RNA-Seq, we observed a large-scale up-regulation of RNA in zygotes derived from Pabpn1l−/− MII oocytes. We found that 9222 genes were up-regulated instead of being degraded in the Pabpn1l-♀/+♂zygote. Both the Btg4 and Cnot61 genes are necessary for the deadenylation process and Pabpn1l  −/− resembled both the Btg4 and Cnot6l knockouts, where 71.2% genes stabilized in the Btg4-♀/+♂ zygote and 84.2% genes stabilized in the Cnot6l-♀/+♂zygote were also stabilized in Pabpn1l-♀/+♂ zygote. BTG4/CNOT7/CNOT6L was partially co-located with PABPN1L in MII oocytes. The above results suggest that PABPN1L is widely associated with CCR4–NOT-mediated maternal mRNA degradation and PABPN1L variants on intron1-exon2 could be a genetic marker of female infertility. Summary sentence. “Ring-like” PABPN1L aggregates was found in the cytoplasm of MII oocytes and in vitro; intron1-exon2 abnormality of Pabpn1l leads female sterile in mice.

scholarly journals Recent progress in translational engineered in vitro models of the central nervous system

Brain ◽  
2020 ◽  
Vol 143 (11) ◽  
pp. 3181-3213 ◽  
Author(s):  
Polyxeni Nikolakopoulou ◽  
Rossana Rauti ◽  
Dimitrios Voulgaris ◽  
Iftach Shlomy ◽  
Ben M Maoz ◽  
...  
Keyword(s):  
Large Scale ◽  
Induced Pluripotent Stem Cell ◽  
In Vitro Models ◽  
Model Systems ◽  
Success Rates ◽  
Recent Developments ◽  
Practical Guidelines ◽  
Organ On A Chip ◽  
Induced Pluripotent

Abstract The complexity of the human brain poses a substantial challenge for the development of models of the CNS. Current animal models lack many essential human characteristics (in addition to raising operational challenges and ethical concerns), and conventional in vitro models, in turn, are limited in their capacity to provide information regarding many functional and systemic responses. Indeed, these challenges may underlie the notoriously low success rates of CNS drug development efforts. During the past 5 years, there has been a leap in the complexity and functionality of in vitro systems of the CNS, which have the potential to overcome many of the limitations of traditional model systems. The availability of human-derived induced pluripotent stem cell technology has further increased the translational potential of these systems. Yet, the adoption of state-of-the-art in vitro platforms within the CNS research community is limited. This may be attributable to the high costs or the immaturity of the systems. Nevertheless, the costs of fabrication have decreased, and there are tremendous ongoing efforts to improve the quality of cell differentiation. Herein, we aim to raise awareness of the capabilities and accessibility of advanced in vitro CNS technologies. We provide an overview of some of the main recent developments (since 2015) in in vitro CNS models. In particular, we focus on engineered in vitro models based on cell culture systems combined with microfluidic platforms (e.g. ‘organ-on-a-chip’ systems). We delve into the fundamental principles underlying these systems and review several applications of these platforms for the study of the CNS in health and disease. Our discussion further addresses the challenges that hinder the implementation of advanced in vitro platforms in personalized medicine or in large-scale industrial settings, and outlines the existing differentiation protocols and industrial cell sources. We conclude by providing practical guidelines for laboratories that are considering adopting organ-on-a-chip technologies.

scholarly journals Symmetry breaking in reconstituted actin cortices

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Enas Abu Shah ◽  
Kinneret Keren
Keyword(s):  
Symmetry Breaking ◽  
Break Symmetry ◽  
Model Systems ◽  
Cortical Actin ◽  
Artificial System ◽  
Actin Cortex ◽  
The Rich ◽  
Oil Emulsions

The actin cortex plays a pivotal role in cell division, in generating and maintaining cell polarity and in motility. In all these contexts, the cortical network has to break symmetry to generate polar cytoskeletal dynamics. Despite extensive research, the mechanisms responsible for regulating cortical dynamics in vivo and inducing symmetry breaking are still unclear. Here we introduce a reconstituted system that self-organizes into dynamic actin cortices at the inner interface of water-in-oil emulsions. This artificial system undergoes spontaneous symmetry breaking, driven by myosin-induced cortical actin flows, which appears remarkably similar to the initial polarization of the embryo in many species. Our in vitro model system recapitulates the rich dynamics of actin cortices in vivo, revealing the basic biophysical and biochemical requirements for cortex formation and symmetry breaking. Moreover, this synthetic system paves the way for further exploration of artificial cells towards the realization of minimal model systems that can move and divide.

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