Complex Interplay of Genes Underlies Invasiveness in Fibrosarcoma Progression Model

Sarcomas are a heterogeneous group of mesenchymal tumours, with a great variability in their clinical behaviour. While our knowledge of sarcoma initiation has advanced rapidly in recent years, relatively little is known about mechanisms of sarcoma progression. JUN-murine fibrosarcoma progression series consists of four sarcoma cell lines, JUN-1, JUN-2, JUN-2fos-3, and JUN-3. JUN-1 and -2 were established from a single tumour initiated in a H2K/v-jun transgenic mouse, JUN-3 originates from a different tumour in the same animal, and JUN-2fos-3 results from a targeted in vitro transformation of the JUN-2 cell line. The JUN-1, -2, and -3 cell lines represent a linear progression from the least transformed JUN-2 to the most transformed JUN-3, with regard to all the transformation characteristics studied, while the JUN-2fos-3 cell line exhibits a unique transformation mode, with little deregulation of cell growth and proliferation, but pronounced motility and invasiveness. The invasive sarcoma sublines JUN-2fos-3 and JUN-3 show complex metabolic profiles, with activation of both mitochondrial oxidative phosphorylation and glycolysis and a significant increase in spared respiratory capacity. The specific transcriptomic profile of invasive sublines features very complex biological relationships across the identified genes and proteins, with accentuated autocrine control of motility and angiogenesis. Pharmacologic inhibition of one of the autocrine motility factors identified, Ccl8, significantly diminished both motility and invasiveness of the highly transformed fibrosarcoma cell. This progression series could be greatly valuable for deciphering crucial aspects of sarcoma progression and defining new prognostic markers and potential therapeutic targets.

A Joint Action in Times of Pandemic: The German BioImaging Recommendations for Operating Imaging Core Facilities During the SARS-Cov-2 Emergency

Operating shared resource laboratories (SRLs) in times of pandemic is a challenge for research institutions. In a multiuser, high‐turnover working space, the transmission of infectious agents is difficult to control. To address this challenge, imaging core facility managers being members of German BioImaging discussed how shared microscopes could be operated with minimal risk of spreading SARS‐CoV‐2 between users and staff. Here, we describe the resulting guidelines and explain their rationale, with a focus on separating users in space and time, protective face masks, and keeping surfaces virus‐free. These recommendations may prove useful for other types of SRLs. © 2020 The Authors. Cytometry Part A published by Wiley Periodicals LLC. on behalf of International Society for Advancement of Cytometry.

Advanced light microscopy core facilities: Balancing service, science and career

Core Facilities (CF) for advanced light microscopy (ALM) have become indispensable support units for research in the life sciences. Their organizational structure and technical characteristics are quite diverse, although the tasks they pursue and the services they offer are similar. Therefore, throughout Europe, scientists from ALM-CFs are forming networks to promote interactions and discuss best practice models. Here, we present recommendations for ALM-CF operations elaborated by the workgroups of the German network of ALM-CFs, German Bio-Imaging (GerBI). We address technical aspects of CF planning and instrument maintainance, give advice on the organization and management of an ALM-CF, propose a scheme for the training of CF users, and provide an overview of current resources for image processing and analysis. Further, we elaborate on the new challenges and opportunities for professional development and careers created by CFs. While some information specifically refers to the German academic system, most of the content of this article is of general interest for CFs in the life sciences. Microsc. Res. Tech. 79:463-479, 2016. © 2016 THE AUTHORS MICROSCOPY RESEARCH AND TECHNIQUE PUBLISHED BY WILEY PERIODICALS, INC.

Live cell multicolor imaging of lipid droplets with a new dye, LD540

A lipophilic dye based on the Bodipy fluorophore, LD540, was developed for microscopic imaging of lipid droplets. In contrast to previous lipid droplet dyes, it can spectrally be resolved from both green and red fluorophores allowing multicolor imaging in both fixed and living cells. Its improved specificity, brightness and photostability support live cell imaging, which was used to demonstrate by two-color imaging lipid droplet motility along microtubules.

A new configuration of the Zeiss LSM 510 for simultaneous optical separation of green and red fluorescent protein pairs

The power and simplicity of genetically encoded fluorophores (fluorescent proteins, FPs) have drawn many molecular biologists to light microscopy. First generation FPs suffered from overlapping excitation and emission spectra, which limited their use together in pairs (Patterson et al., J Cell Sci 2001;114 (Part 5):837-838). Image acquisition and processing techniques, collectively known as linear unmixing, have been developed to separate overlapping fluorescence signals encountered in the imaging of FP pairs and also in FRET. These specialized techniques are not without their potential drawbacks, including limitations on sensitivity and time-resolution for live cell imaging, and the risk of artifact in the hands of nonspecialists. With the advent of a new generation of red-shifted FPs (Shaner et al., Nat Biotechnol 2004;22:1567-1572; Verkhusha and Lukyanov, Nat Biotechnol 2004;22:289-296) careful selection of excitation sources and emission filters obviate the need for linear unmixing when simple two channel imaging of FPs is required. Here we introduce a new configuration of the Zeiss LSM 510 laser scanning confocal microscope, optimized for live cell imaging of green fluorescent protein (GFP) together with spectral variants such as mRFP1 and mCherry using standard photo-multipliers. A 2 mW, 594 nm HeNe laser was chosen as the excitation source for the red FP. This wavelength efficiently excites the aforementioned red variants without limiting the detection range of GFP emission during simultaneous two-channel imaging. Compared to excitation of GFP and mCherry at 488 and 543 nm, excitation at 488 and 594 nm approximately doubles the sensitivity of GFP detection and eliminates bleed-through of GFP into the mCherry channel. However, sensitivity of mCherry detection is decreased by 30%, suggesting the need for red FPs having longer emission peaks. Practical advantages to the simultaneous optical separation of FPs with nonoverlapping emission spectra include simplicity, robustness, reduced risk of artifact, and increased sensitivity during live cell imaging.

Establishment and characterization of clonal cell lines derived from a fibrosarcoma of the H2-K/V-JUN transgenic mouse. A model of H2-K/V-JUN mediated tumorigenesis

We used fibrosarcoma from an H2-K/V-JUN transgenic mouse to derive a series of three immortal cell lines (JUN-1, -2, and -3). The cell lines exhibit strikingly different behavior regarding phenotype transformation. Features examined include contact inhibition and density limitation of growth, proliferation, invasiveness, motility, and organization of the microfilament system. Overall, JUN-2 and JUN-3 represent extreme phenotypes, with JUN-2 having a phenotype indicative of low-level cellular transformation and JUN-3 meeting all the criteria of the transformed phenotype. JUN-1 cells can also be regarded as transformed, but to a lesser extent than JUN-3. Their phenotype is in the majority of characteristics intermediary between JUN-2 and JUN-3. The transformation status is inversely related to the expression of the V-JUN transgene, which is the highest in JUN-2, lower in JUN-1 and very low in JUN-3. This might be related to the MHC class I promoter driving its expression and to the general observation of repression of MHC class I genes coupled with cellular transformation. Based on this premise, we present a model of H2-K/V-JUN-mediated tumorigenesis, in which v-jun-conditioned transformation represents merely an initial phase of tumorigenesis. Later during tumor progression, additional oncogenes are activated and/or tumor suppressor genes inactivated, leading on the one hand to further exacerbation of the transformed phenotype, and on the other hand to the repression of the H2-K/V-JUN transgene (fixed in JUN-3). We believe that the system of JUN cell lines can be valuable for further molecular analysis of transformation-related traits.

Dried-droplet probe preparation on AnchorChip targets for navigating the acquisition of matrix-assisted laser desorption/ionization time-of-flight spectra by fluorescence of matrix/analyte crystals

We have developed a dried-droplet probe preparation method for peptide mass fingerprinting by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS), which uses AnchorChip targets and alpha-cyano-4-hydroxycinnamic acid (CHCA) as a matrix. Upon drying of a matrix and analyte mixture on the AnchorChip, salts and low molecular weight contaminants were pooled at the hydrophilic metal anchor, whereas 10-50 microm matrix/peptide crystals firmly adhered at the surface of a hydrophobic polymer and the entire target could be subsequently washed by submerging it in 5% formic acid for 2-3 min. Epifluorescence microscopy suggested that peptides were completely co-localized with CHCA crystals at the AnchorChip surface. Fluorescent images of the probes were of good contrast and were background-free, compared with images taken by a video camera built into the ion source. CHCA/peptide crystals were easy to recognize at the surface and peptide mass maps were acquired from them without further adjustment of the position of the laser beam. These crystals were remarkably stable towards the laser depletion and almost no matrix-related ions were typically observed in the low m/z region of peptide mass maps. The sensitivity of the peptide mass mapping was at the low-femtomole level.

Our Experiences with Development of Digitised Video Streams and Their Use in Animal-free Medical Education

Alternatives and their teaching are an essential part of the curricula at the Faculty of Medicine. Dynamic screen-based video recordings are the most important type of alternative models employed for teaching purposes. Currently, the majority of teaching materials for this purpose are based on PowerPoint presentations, which are very popular because of their high versatility and visual impact. Furthermore, current developments in the field of image capturing devices and software enable the use of digitised video streams, tailored precisely to the specific situation. Here, we demonstrate that with reasonable financial resources, it is possible to prepare video sequences and to introduce them into the PowerPoint presentation, thereby shaping the teaching process according to individual students’ needs and specificities.

The role of intracellular zinc in modulation of life and death of Hep-2 cells

Varying intracellular concentrations of zinc in laryngeal Hep-2 cells in relation to changing cultivation conditions in vitro were determined by atomic absorption spectrophotometry. Upon standard cultivation in DMEM with 10% serum, the mean concentration of zinc was determined at 0.88 +/- 0.09 microg/mg protein, with substantially decreased values in the cells exposed to a low-serum medium. Next, the study of the effects of a series of physiological and supraphysiological concentrations of ZnSO4 on laryngeal cells and their correlation with determined intracellular concentrations of zinc was performed. It was found that zinc concentrations above 100 microM were toxic to Hep-2 cells, inducing cell death in the interval of 96 h as determined by videomicroscopy, selective nuclear staining, and immunofluorescence detection of caspase-3 and specific cytokeratin 18 fragment. Both types of cell death were observed, with apoptosis being induced at moderately toxic zinc concentration of 150 microM and necrosis at higher zinc concentrations of 300 microM and 750 microM, respectively. Lower concentrations (1.5-100 microM), on the other hand, did not produce any measurable changes in cell morphology and function in the same time interval. Zinc at concentration of 1.5 microM was found to slightly enhance proliferation of Hep-2 cells up to the certain time point, which seemed to correlate with maximal tolerable momentary intracellular level of zinc. These results illustrate the importance of determining the intracellular levels of zinc when trying to characterize the effect of exogenous zinc on life and death of laryngeal cells.

3D-computer based reconstructions of apoptotic nuclei

We present a 3D-model of apoptotic nuclei of HL-60 cells treated with 10 g/ml Etoposide (topoisomerase II inhibitor) for 24 hours. The static model was generated from a series of optical sections obtained through a confocal microscope by freeware and shareware graphical programs available in the Internet. Its animation was done by 3D Studio Max. We demonstrate the appearance of typical fragmentation and condensation of chromatin accompanied by its aggregation to the inner side of the nuclear membrane.

[Zinc and its role in the regulation of cell death]

Zinc is a key element for maintenance of the structural and functional integrity of eukaryotic cells and tissues. In living systems, it forms stable complexes with macromolecules as well as so called labile pools called zincosomes, which are nowadays considered crucial for the regulation of apoptosis and cell proliferation. Zinc may block apoptosis induced by many external factors by inhibiting caspases and endonucleases, through interactions with transcription factors and kinases or due to its antioxidant activities. On the other hand, depletion of zinc may lead to rapid activation of apoptotic cascade and consequent cell death in many types of cells. Imbalances in intracellular zinc pools lead to improper regulation of cell death and proliferation, which is often causing or accompanying diseases. Therefore, detailed elucidation of the role of zinc in these regulations presents a solution for various pathophysiological conditions.

Toxic effects of chromium acetate hydroxide on cells cultivated in vitro

Many human activities, particularly industrial ones, result in an ever-growing production of toxic waste materials. The dynamics of the toxic effects of chromium acetate hydroxide, which is found in high concentrations in a waste sediment produced in the Czech Republic, were assessed by using a battery of in vitro tests carried out on two cell lines: L-929 (mouse fibroblasts) and Hep 2 (human laryngeal cells). Various markers of cell damage were assessed by phase-contrast, video and fluorescence microscopy, fluorometry, and DNA analysis. Chromium acetate hydroxide, over a concentration range of 1-0.02mol/l induced immediate cell death by fixation, whereas, at 0.002mol/l, the treated cells died in a much slower, more discrete manner. All the detected markers of cell damage, whether immediate or slow, clearly demonstrated that the cells died by necrosis. On the other hand, test concentration of 0.001mol/l appeared to constitute a threshold at which no pathological changes of Hep 2 cells were observed over 96 hours. We conclude that chromium acetate hydroxide has a high toxic potential in vitro, which should be considered when studying the toxicity of waste materials containing it.

The dynamics of the hexavalent chromium induced apoptotic patterns in vitro

Although hexavalent chromium has been shown to induce apoptosis in cells cultivated in vitro, there appear to be no studies focusing on the dynamics of this process. To find out about dynamic patterns of hexavalent chromium-induced apoptosis, we treated Hep2 cells with 150 micrograms/ml potassium chromate and recorded their behavior as well as appearance of some crucial organelles using different morphological and biochemical methods. We found that Hep2 cells showed the earliest observable changes at 6 hours after the treatment (blebbing, chromatin shrinkage), with the entire apoptotic process lasting up to 24 hours. While all the observed cell features clearly prove apoptosis induced by hexavalent chromium, a typical apoptotic hallmark, DNA ladder, seems not to occur in this type of cells. On the other hand, in HL60 cells, used as a control, this ladder was observable.

Apoptosis - when the cells begin to dance

We present a 24-hour time-lapse videosequence of in vitro behavior of Hep-2 cells treated with 10 m g/ml Etoposide, a topoisomerase II inhibitor. The cell behavior was recorded by a Mitsubishi video recorder, HS-S5600. In the presented sequence, we show the typical cell rounding accompanied by formation of numerous pseudopodia and rapid rhythmical contractions, so called membrane blebbing known as "dance of death".

The role of mitochondria in apoptosis induced in vitro

Cell death remains the focus of in vitro toxicology. Xenobiotics are capable of bringing about two types of cell death: apoptosis and necrosis. From our previous study we know that cells treated with xenobiotics showed very dynamic changes in their morphology, particularly vigorous movement of the plasma membrane. Such changes probably depend on adequate energy supply. This observation stands in contradiction with published data showing that generation of ATP in mitochondria is altered very early in apoptosis. In this study we analysed the relationship between mitochondrial activity and cell death induced by Etoposide, a selective inhibitor of topoisomerase II, treatment (10 microg/ml). As a model system we used stabilised cell line Hep2. Several markers of apoptosis, including typical cell morphology and DNA ladder formation were measured. The dynamics of morphological changes was recorded by the time-lapse videomicroscopy. We measured mitochondrial membrane potential with a specific fluorochrome DASPMI, quantification was done by microfluorometric assessment. Our data show that mitochondrial activity was maintained during the first 6 hours after the treatment with Etoposide, at the same time substantial changes in cell morphology as well as typical DNA fragmentation were observed.