Disruption Of Cell Division Research Articles

Malignant Pleural Mesothelioma: A Comprehensive Review.

Mesotheliomas are hyperplastic tumors that envelop the serosal membranes that safeguard the body's external surfaces. Although certain instances may exhibit indolent characteristics, a significant number of tumors demonstrate rapid progression and a poor prognosis. Mesotheliomas are typically categorized as benign or malignant, with malignant mesothelioma being more frequently linked to asbestos exposure. Malignant pleural mesothelioma (MPM) predominantly impacts males and often emerges in the late 50 s or beyond, characterized by a median age of early 70 s among patients exposed to asbestos lasting from 2 to 4 decades. Respiratory exposure to asbestos particles leads to the development of malignant mesothelioma, characterized by recurrent inflammation, disruption of cell division, activation of proto-oncogenes, and generation of free radicals. In pleural mesothelioma, BAP1, CDKN2A, and NF are the most often mutated genes. Accurate diagnosis and assessment usually require the use of chest computed tomography (CT) scans, magnetic resonance imaging (MRI), and positron emission tomography (PET). Radiation therapy, immunotherapy, chemotherapy, and surgery are some of the treatment options that are currently available. This systematic review provides a comprehensive analysis of the latest research, biomarkers, evaluation, and management strategies for malignant pleural mesothelioma.

Connecting sequence features within the disordered C-terminal linker of B. subtilis FtsZ to functions and bacterial cell division.

Intrinsically disordered regions (IDRs) can function as autoregulators of folded enzymes to which they are tethered. One such example is the disordered C-terminal tail (CTT) of FtsZ, an essential GTPase in bacterial cell division. FtsZs feature a folded core and a CTT that encompasses a poorly conserved, disordered C-terminal linker (CTL) and a conserved 17-residues C-terminal peptide (CT17). Sites for GTPase activity of FtsZs are formed at the interface between GTP binding sites and T7 loops on cores of adjacent subunits within dimers. Here, we explore the molecular, evolutionary, and cellular bases for how autoregulatory functions of the CTT are realized in Bacillus subtilis FtsZ (Bs-FtsZ). Molecular simulations show statistically significant CTL-mediated contacts between the T7 loop and the CT17. Statistical coupling analysis of more than 1000 orthologs reveals clear covariation of the T7 loop and the CT17 with most of the core domain whereas the CTL is under independent selection. Furthermore, we also identify a conserved set of non-random sequence patterns within the CTLs, including linear clustering of polar and acidic residues, that modulate the interaction between the core and the CTT. To test how the non-random patterns of CTLs mediate CTT-core interactions and modulate FtsZ functionalities, we designed Bs-FtsZ variants by altering the patterning of oppositely charged residues within the CTL. Such alterations disrupt the core-CTT interactions, lead to anomalous assembly and inefficient GTP hydrolysis in vitro, and protein degradation, aberrant assembly, and disruption of cell division in vivo. Our findings suggest that viable CTLs in FtsZs are likely to be IDRs that encompass the non-random, functionally relevant sequence patterns that also preserve three-way covariation of the CT17, the T7 loop, and core domain.

Real-Time Monitoring of the Effect of Tumour-Treating Fields on Cell Division Using Live-Cell Imaging.

The effects of electric fields (EFs) on various cell types have been thoroughly studied, and exhibit a well-known regulatory effect on cell processes, implicating their usage in several medical applications. While the specific effect exerted on cells is highly parameter-dependent, the majority of past research has focused primarily on low-frequency alternating fields (<1 kHz) and high-frequency fields (in the order of MHz). However, in recent years, low-intensity (1–3 V/cm) alternating EFs with intermediate frequencies (100–500 kHz) have been of topical interest as clinical treatments for cancerous tumours through their disruption of cell division and the mitotic spindle, which can lead to cell death. These aptly named tumour-treating fields (TTFields) have been approved by the FDA as a treatment modality for several cancers, such as malignant pleural mesothelioma and glioblastoma multiforme, demonstrating remarkable efficacy and a high safety profile. In this work, we report the results of in vitro experiments with HeLa and MCF-10A cells exposed to TTFields for 18 h, imaged in real time using live-cell imaging. Both studied cell lines were exposed to 100 kHz TTFields with a 1-1 duty cycle, which resulted in significant mitotic and cytokinetic arrest. In the experiments with HeLa cells, the effects of the TTFields’ frequency (100 kHz vs. 200 kHz) and duty cycle (1-1 vs. 1-0) were also investigated. Notably, the anti-mitotic effect was stronger in the HeLa cells treated with 100 kHz TTFields. Additionally, it was found that single and two-directional TTFields (oriented orthogonally) exhibit a similar inhibitory effect on HeLa cell division. These results provide real-time evidence of the profound ability of TTFields to hinder the process of cell division by significantly delaying both the mitosis and cytokinesis phases of the cell cycle.

Auxin application to maize plants at flowering increases abundance and activity of plasma membrane H+‐ATPase in developing maize kernels

AbstractBackgroundThe kernel number of maize (Zea mays L.) at maturity is mainly determined at the time around pollination. Kernel abortion frequently occurs during this period, leading to grain yield depressions. Plasma membrane (PM) H+‐ATPase was identified as a key enzyme responsible for supply of assimilates to the developing maize kernels shortly after pollination.AimsThis study aimed at stimulating PM H+‐ATPase activity in the kernels by in vivo application of the auxin indole‐3‐acetic acid (IAA) to maize plants at flowering, leading to an improved hexose uptake and finally to a better kernel set.MethodsMaize plants were cultivated under well‐watered conditions using the container technique. IAA was applied to unstressed maize plants twice, 2 days before controlled pollination and at pollination (application rate per plant: 1.9 mL of 1.5 mM IAA). The developing kernels were harvested 2 days after pollination, and PM vesicles were isolated and purified using two‐phase partitioning.ResultsThe in vitro hydrolytic activity of the PM H+‐ATPase was significantly stimulated by 22% due to in vivo IAA application (control: 0.99 ± 0.05, IAA treatment: 1.21 ± 0.03* μmol inorganic phosphate mg–1 protein min–1). Vmax was significantly increased by IAA treatment, whereas Km was reduced. The maximal pH gradient (ΔA492) at the PM was increased by 10% (control: 0.071 ± 0.002, IAA treatment: 0.078 ± 0.002*). IAA caused a significant increase of PM H+‐ATPase abundance in the vesicles. Concentrations of sucrose and hexoses as well as acid invertase activity in the kernels were unaffected by IAA treatment. However, at maturity kernel numbers per cob were significantly decreased causing grain yield reductions of 19%.ConclusionsIncreased PM H+‐ATPase activity could not be translated into grain yield improvements. Probably the auxin application occurred too early during kernel development. As cytokinins play a key role during pollination, auxin application at this stage may have disturbed the phytohormone balance, causing disruption of cell division and a rather early onset of cell extension due to increased IAA concentrations. In further studies, it should be tested if applications of cytokinin at flowering or of IAA at a later growth stage have positive impacts on kernel set.

Antibacterial activity of alkyl gallates is a combination of direct targeting of FtsZ and permeabilization of bacterial membranes.

Alkyl gallates are compounds with reported antibacterial activity. One of the modes of action is binding of the alkyl gallates to the bacterial membrane and interference with membrane integrity. However, alkyl gallates also cause cell elongation and disruption of cell division in the important plant pathogen Xanthomonas citri subsp. citri, suggesting that cell division proteins may be targeted by alkyl gallates. Here, we use Bacillus subtilis and purified B. subtilis FtsZ to demonstrate that FtsZ is a direct target of alkyl gallates. Alkyl gallates disrupt the FtsZ-ring in vivo, and cause cell elongation. In vitro, alkyl gallates bind with high affinity to FtsZ, causing it to cluster and lose its capacity to polymerize. The activities of a homologous series of alkyl gallates with alkyl side chain lengths ranging from five to eight carbons (C5–C8) were compared and heptyl gallate was found to be the most potent FtsZ inhibitor. Next to the direct effect on FtsZ, alkyl gallates also target B. subtilis membrane integrity—however the observed anti-FtsZ activity is not a secondary effect of the disruption of membrane integrity. We propose that both modes of action, membrane disruption and anti-FtsZ activity, contribute to the antibacterial activity of the alkyl gallates. We propose that heptyl gallate is a promising hit for the further development of antibacterials that specifically target FtsZ.

Gene silencing in Fucus embryos: developmental consequences of RNAi-mediated cytoskeletal disruption.

Brown algae (Phaeophyceae) are an important algal class that play a range of key ecological roles. They are often important components of rocky shore communities. A number of members of the Fucales and Ectocarpales have provided models for the study of multicellular evolution, reproductive biology and polarized development. Indeed the fucoid algae exhibit the unusual feature of inducible embryo polarization, allowing many classical studies of polarity induction. The potential of further studies of brown algae in these important areas has been increasingly hindered by the absence of tools for manipulation of gene expression that would facilitate further mechanistic analysis and gene function studies at a molecular level. The aim of this study was to establish a method that would allow the analysis of gene function through RNAi-mediated gene knockdown. We show that injection of double-stranded RNA (dsRNA) corresponding to an α-tubulin gene into Fucus serratus Linnaeus zygotes induces the loss of a large proportion of the microtubule cytoskeleton, leading to growth arrest and disruption of cell division. Injection of dsRNA targeting β-actin led to reduced rhizoid growth, enlarged cells and the failure to develop apical hair cells. The silencing effect on actin expression was maintained for 3months. These results indicate that the Fucus embryo possesses a functional RNA interference system that can be exploited to investigate gene function during embryogenesis.

CDNA phage display as a novel tool to screen for cellular targets of chemical compounds

cDNA phage display is frequently used in drug development to screen for cellular target of drugs. However, in toxicology, cDNA phage display remains unexplored, although it has large potential in this field. In this study, cDNA phage display is demonstrated as a novel tool to screen for interactions between chemical compounds and cellular targets. The knowledge of these target interactions is valuable to have a more complete understanding of the mechanisms of action of chemical compounds. Bisphenol A (BPA) was selected as a model compound for this study. By selection of the cellular proteins that bind BPA with cDNA phage display, it was possible to identify a known cellular target of BPA, tubulin α and a possible novel cellular target of BPA, transforming acidic coiled-coil containing protein 3. Both these cellular proteins are involved in the mechanism of cell division. The disruption of cell division is a known non-genomic effect of BPA. Non-genomic effects are not mediated by differences in gene expression and therefore important mechanistic information might be missed with the widely used differential gene expression techniques for mode of action research. This cDNA phage display technique can provide important additional information about the interaction of chemical compounds with cellular targets that mediates these non-genomic actions and therefore gives complementary information to toxicogenomic studies to obtain a more complete understanding of the mechanism of action of chemical compounds.

Therapeutic Efficacy of a Herpes Simplex Virus With Radiation or Temozolomide for Intracranial Glioblastoma After Convection-enhanced Delivery

The herpes simplex virus-1 (HSV-1)-infected cell protein 0 (ICP0) is an E3 ubiquitin ligase implicated in cell cycle arrest and DNA repair inhibition. Convection-enhanced delivery (CED) of either the replication-defective, ICP0-producing HSV-1 mutant, d106, or the recombinant d109, devoid of all viral genome expression, was performed to determine the in vivo efficacy of ICP0 in combination with ionizing radiation (IR) or systemic temozolomide (TMZ) in the treatment of glioblastoma multiforme (GBM). Intracranial U87-MG xenografts were established in athymic nude mice. Animal survival was determined after mice underwent intracranial CED of either the replication-defective d106 or d109 viruses, or Hanks' balanced salt solution (HBSS), before a single session of whole-brain irradiation or TMZ treatment. Median survival for animals that underwent treatment with HBSS alone, d109 alone, d106 alone, HBSS + IR, HBSS + TMZ, d109 + IR, d106 + IR, and d106 + TMZ was 28, 35, 41, 39, 44, 39, 68 (P < 0.01), and 66 days (P < 0.01), respectively. Intracerebral d106 CED resulted in a significant increase in athymic nude mouse survival when combined with IR or TMZ. d106 CED allows for distribution of HSV-1 in human GBM xenografts and persistent viral infection.

Cell Size: A Matter of Life or Death?

Proper growth and development of multicellular organisms require the tight regulation of cell growth, cell division and cell death. A recent study has identified a novel regulatory link between two of these processes: cell growth and cell death.

Heat Stress Effects on Protein Accumulation of Maize Endosperm

Heat stress is a major factor limiting crop yield in many agricultural regions. During the early stage of kernel development, heat stress is particularly detrimental to subsequent dry matter accumulation since it causes disruption of cell division, sugar metabolism, and starch biosynthesis in the endosperm. The effects of heat stress on protein accumulation, however, is less well understood. Therefore, the objective of this study was to determine the mechanisms by which heat stress decreases protein accumulation and alters composition of developing maize (Zea mays L.) kernels. In this study, maize ears were heat stressed for 2 and 4 d at continuous 35°C starting at 5 d after pollination (DAP). Endosperms were analyzed for the relative proportion of each Osborne protein solubility class fraction and for individual zein proteins. The 2‐ and 4‐d heat stress (DHS) treatment caused a 20 and 48% reduction in kernel final dry weight, respectively, and protein content was similarly reduced. Specifically, zein content was reduced by an average of 53%, but zein composition was only mildly affected. The concentrations of glutelin and albumin plus globulin tended to increase throughout most of 4‐DHS kernel development. L‐[35S]‐methionine incorporation in the zein fraction was delayed by the 4 DHS when compared to control and 2‐DHS treated kernels. Therefore, we concluded that heat stress during early stages of endosperm development repressed zein accumulation at the synthesis level. In contrast, later in development, zein accumulation appeared to be repressed mainly by protein degradation, which appears to be a part of the natural progression of kernel development since there was no apparent significant effect of heat stress treatments on this process.

Resveratrol-induced G 2 arrest through the inhibition of CDK7 and p34 CDC2 kinases in colon carcinoma HT29 cells

Resveratrol (3,5,4′-trihydroxystilbene), a phytoalexin found in grapes and other food products, has been shown to have cancer chemopreventive activity. However, the mechanism of the anti-carcinogenic activity is not well understood. Here, we offer a possible explanation of its anti-tumor effect. Based on flow cytometric analysis, resveratrol inhibited the proliferation of HT29 colon cancer cells and resulted in their accumulation in the G 2 phase of the cell cycle. Western blot analysis and kinase assays demonstrated that the perturbation of G 2 phase progression by resveratrol was accompanied by the inactivation of p34 CDC2 protein kinase, and an increase in the tyrosine phosphorylated (inactive) form of p34 CDC2. Kinase assays revealed that the reduction of p34 CDC2 activity by resveratrol was mediated through the inhibition of CDK7 kinase activity, while CDC25A phosphatase activity was not affected. In addition, resveratrol-treated cells were shown to have a low level of CDK7 kinase-Thr 161-phosphorylated p34 CDC2. These results demonstrated that resveratrol induced cell cycle arrest at the G 2 phase through the inhibition of CDK7 kinase activity, suggesting that its anti-tumor activity might occur through the disruption of cell division at the G 2/M phase.

Ultrastructural characterization of maize (Zea mays L.) kernels exposed to high temperature during endosperm cell division

This study reports the ultrastructural changes in maize endosperm that result from exposure to high temperature during cell division. Kernels were grown in vitro at 25 ºC continuously (control) and at 5 d after pollination (DAP) subsamples were transferred to continuous 35 ºC for either 4 or 6 d. The 4 d treatment reduced kernel mass by 40% and increased kernel abortion three‐fold. The 6‐d high‐temperature treatment resulted in a 77% reduction in kernel mass and a 12‐fold increase in kernel abortion. Evaluation of the kernels at 11 DAP using scanning and transmission electron microscopy revealed that the reduced kernel mass and/or abortion was associated with the disruption of cell division and amyloplast biogenesis in the periphery of the endosperm. This was further confirmed by the presence of an irregular‐shaped nucleus, altered size of the nucleolus, highly dense nucleoplasm, and a decrease in the number of proplastids and amyloplasts. Thus, the endosperm cavity was not filled, the total number of endosperm cells was reduced by 35 and 70%, and the number of starch granules was decreased by 45 and 80% after exposure to 4 and 6 d of high‐temperature treatments, respectively. This also resulted in a 35–70% reduction in total starch accumulation. KI/I2 staining and light microscopy revealed that starch accumulation in the peripheral endosperm cells was reduced more severely than in the central zones. However, the scanning electron micrographs of cells from the central endosperm showed that the number and the size of apparently viable amyloplasts were reduced and isolated granules were smaller and/or showed enhanced pitting. These ultrastructural data support the hypothesis that high temperature during endosperm cell division reduces kernel sink potential and subsequently mature kernel mass, mainly by disrupting cell division and amyloplast biogenesis in the peripheral and central endosperm.

Specific destruction of kinetochore protein CENP-C and disruption of cell division by herpes simplex virus immediate-early protein Vmw110.

Examination of cells at the early stages of herpes simplex virus type 1 infection revealed that the viral immediate-early protein Vmw110 (also known as ICP0) formed discrete punctate accumulations associated with centromeres in both mitotic and interphase cells. The RING finger domain of Vmw110 (but not the C-terminal region) was essential for its localization at centromeres, thus distinguishing the Vmw110 sequences required for centromere association from those required for its localization at other discrete nuclear structures known as ND10, promyelocytic leukaemia (PML) bodies or PODs. We have shown recently that Vmw110 can induce the proteasome-dependent loss of several cellular proteins, including a number of probable SUMO-1-conjugated isoforms of PML, and this results in the disruption of ND10. In this study, we found some striking similarities between the interactions of Vmw110 with ND10 and centromeres. Specifically, centromeric protein CENP-C was lost from centromeres during virus infection in a Vmw110- and proteasome-dependent manner, causing substantial ultrastructural changes in the kinetochore. In consequence, dividing cells either became stalled in mitosis or underwent an unusual cytokinesis resulting in daughter cells with many micronuclei. These results emphasize the importance of CENP-C for mitotic progression and suggest that Vmw110 may be interfering with biochemical mechanisms which are relevant to both centromeres and ND10.

Chloral hydrate mediated inhibition of cell division and of proton synthesis.

Chloral hydrate (along with other anaesthetics and hypnotics) is an inhibitor of cell division. We have shown that chloral hydrate is also an inhibitor of protein synthesis. This inhibition is unlikely to be a result of either of the disruption of cell division or of interference with the function of microtubules. The ability of chloral hydrate to inhibit cell division may result from its ability to inhibit protein synthesis.