Synchronization of mammalian cell cultures by serum deprivation

HN1 Is Enriched in the S-Phase, Phosphorylated in Mitosis, and Contributes to Cyclin B1 Degradation in Prostate Cancer Cells

HN1 has previously been shown as overexpressed in various cancers. In Prostate cancer, it regulates AR signaling and centrosome-related functions. Previously, in two different studies, HN1 expression has been observed as inversely correlated with Cyclin B1. However, HN1 interacting partners and the role of HN1 interactions in cell cycle pathways have not been completely elucidated. Therefore, we used Prostate cancer cell lines again and utilized both transient and stable inducible overexpression systems to delineate the role of HN1 in the cell cycle. HN1 characterization was performed using treatments of kinase inhibitors, western blotting, flow cytometry, immunofluorescence, cellular fractionation, and immunoprecipitation approaches. Our findings suggest that HN1 overexpression before mitosis (post-G2), using both transient and stable expression systems, leads to S-phase accumulation and causes early mitotic exit after post-G2 overexpression. Mechanistically, HN1 interacted with Cyclin B1 and increased its degradation via ubiquitination through stabilized Cdh1, which is a co-factor of the APC/C complex. Stably HN1-expressing cells exhibited a reduced Cdt1 loading onto chromatin, demonstrating an exit from a G1 to S phenotype. We found HN1 and Cdh1 interaction as a new regulator of the Cyclin B1/CDK1 axis in mitotic regulation which can be explored further to dissect the roles of HN1 in the cell cycle.

1α,25-Dihydroxyvitamin D3 (VD3) Shows a Neuroprotective Action Against Rotenone Toxicity on PC12 Cells: An In Vitro Model of Parkinson's Disease

Parkinson's disease (PD) is characterized by dopaminergic cell loss in the substantia nigra, and PD brains show neuroinflammation, oxidative stress, and mitochondrial dysfunction. The study evaluated the neuroprotective activity of 1α,25-dihydroxy vitamin D3 (VD3), on the rotenone (ROT)-induced cytotoxicity in PC12 cells. The viability parameters were assessed by the MTT and flow cytometry, on cells treated or not with VD3 and/or ROT. Besides, ROS production, cell death, mitochondrial transmembrane potential, reduced GSH, superoxide accumulation, molecular docking (TH and Keap1-Nrf2), and TH, Nrf2, NF-kB, and VD3 receptor protein contents by western blot were evaluated. VD3 was shown to improve the viability of ROT-exposed cells. Cells exposed to ROT showed increased production of ROS and superoxide, which decreased after VD3. ROT decrease in the mitochondrial transmembrane potential was prevented, after VD3 treatment and, VD3 was shown to interact with tyrosine hydroxylase (TH) and Nrf2. While ROT decreased TH, Nrf2, and NF-kB expressions, these effects were reversed by VD3. In addition, VD3 also increased VD3 receptor protein contents and values went back to those of controls after ROT exposure. VD3 protects PC12 cells against ROT damage, by decreasing oxidative stress and improving mitochondrial function. One target seems to be the TH molecule and possibly an indirect Nrf2 activation could also justify its neuroprotective actions on this PC12 cell model of PD.

Synergistic inhibitory effect of human umbilical cord matrix mesenchymal stem cells-conditioned medium and atorvastatin on MCF7 cancer cells viability and migration

Recent studies have demonstrated inhibitory effects of mesenchymal stem cells on breast tumors. Likewise, the emerging interest in statins as anticancer agents is based on their pleiotropic effects. In the present study, we investigated whether atorvastatin and umbilical cord matrix derived mesenchymal stem cells-conditioned medium affect the MCF7 cancer cells viability and interactions. We measured the viability of MCF7 cancer cells by MTT assay, flow cytometry, and quantitative real-time PCR. Two-dimensional culture and hanging drop aggregation assay illustrated the morphological changes. We traced the MCF7 migration via scratch-wound healing test and trans-well assay. The results showed the inhibition of cancer cell viability in all treated groups compared to the control group. The effect of atorvastatin and conditioned medium combination was significantly more than each substance separately. The morphological changes indicated apoptosis in treated cells. The annexin V/PI flow cytometry especially in the combination-treated group displayed decreasing in DNA synthesis and cell cycle arrest in G1 and G2/M phases. As well, the mRNA expressions of caspases 3, 8, 9, and Bcl-2 genes were along with extrinsic and intrinsic apoptosis pathways. Conditioned medium disrupted the connections between cancer cells, so the spheroids in three-dimensional configuration lost their order and dispersed. The migration of treated cells across the wound area and trans-well diminished, particularly by the conditioned medium and atorvastatin combination. There fore, the synergistic anti-proliferative and anti-motility effect of atorvastatin along with human umbilical cord mesenchymal stem cells-derived conditioned medium on MCF7 breast cancer cells have been proved. The results might lead the development of novel adjuvant anticancer therapeutics based on targeting or modifying the extracellular matrix to increase chemotherapy results or to prevent metastatic colonization. Schematic representation of "Synergistic Inhibitory Effect of Human Umbilical Cord Matrix Mesenchymal Stem Cells-Conditioned Medium and Atorvastatin on MCF7 Cancer Cells Viablity and Migration" by: Dr. Reyhaneh Abolghasemi, Dr. Somayeh Ebrahimi-barough, Proffesor. Jafar Ai.

Evaluation of anticancer activity in vitro of a stable copper(I) complex with phosphine-peptide conjugate

[CuI(2,9-dimethyl-1,10-phenanthroline)P(p-OCH₃-Ph)₂CH₂SarcosineGlycine] (1-MPSG), highly stable in physiological media phosphino copper(I) complex—is proposed herein as a viable alternative to anticancer platinum-based drugs. It is noteworthy that, 1-MPSG significantly and selectively reduced cell viability in a 3D spheroidal model of human lung adenocarcinoma (A549), in comparison with non-cancerous HaCaT cells. Confocal microscopy and an ICP-MS analysis showed that 1-MPSG effectively accumulates inside A549 cells with colocalization in mitochondria and nuclei. A precise cytometric analysis revealed a predominance of apoptosis over the other types of cell death. In the case of HaCaT cells, the overall cytotoxicity was significantly lower, indicating the selective activity of 1-MPSG towards cancer cells. Apoptosis also manifested itself in a decrease in mitochondrial membrane potential along with the activation of caspases-3/9. Moreover, the caspase inhibitor (Z-VAD-FMK) pretreatment led to decreased level of apoptosis (more pronouncedly in A549 cells than in non-cancerous HaCaT cells) and further validated the caspases dependence in 1-MPSG-induced apoptosis. Furthermore, the 1-MPSG complex presumably induces the changes in the cell cycle leading to G2/M phase arrest in a dose-dependent manner. It was also observed that the 1-MPSG mediated intracellular ROS alterations in A549 and HaCaT cells. These results, proved by fluorescence spectroscopy, and flow cytometry, suggest that investigated Cu(I) compound may trigger apoptosis also through ROS generation.

Continuous monitoring of cell transfection efficiency with micropatterned substrates

The effect of cell-cell contact on gene transfection is mainly unknown. Usually, transfection is carried out in batch cell cultures without control over cellular interactions, and efficiency analysis relies on complex and expensive protocols commonly involving flow cytometry as the final analytical step. Novel platforms and cell patterning are being studied to control cellular interactions and improve quantification methods. In this study, we report the use of surface patterning of fibronectin for the generation of two types of mesenchymal stromal cell patterns: single-cell patterns without cell-to-cell contact, and small cell-colony patterns. Both scenarios allowed the integration of the full transfection process and the continuous monitoring of thousands of individualized events by fluorescence microscopy. Our results showed that cell-to-cell contact clearly affected the transfection, as single cells presented a maximum transfection peak 6 h earlier and had a 10% higher transfection efficiency than cells with cell-to-cell contact.

The Effects of Exercise Serum From Prepubertal Girls and Women on In Vitro Myoblast and Osteoblast Proliferation and Differentiation

PURPOSE

In girls and women, the authors studied the effects of an acute bout of low-impact, moderate-intensity exercise serum on myoblast and osteoblast proliferation in vitro.

METHODS

A total of 12 pre/early pubertal girls (8-10 y old) and 12 women (20-30 y old) cycled at 60% VO2max for 1 hour followed by 1-hour recovery. Blood samples were collected at rest, mid-exercise, end of exercise, mid-recovery, and end of recovery. C2C12 myoblasts and MC3T3E1 osteoblasts were incubated with serum from each time point for 1 hour, then monitored for 24 hours (myoblasts) or 36 hours (osteoblasts) to examine proliferation. Cells were also monitored for 6 days (myoblasts) to examine myotube formation and 21 days (osteoblasts) to examine mineralization.

RESULTS

Exercise did not affect myoblast or osteoblast proliferation. Girls exhibited lower cell proliferation relative to women at end of exercise (osteoblasts, P = .041; myoblasts, P = .029) and mid-recovery (osteoblasts, P = .010). Mineralization was lower at end of recovery relative to rest (P = .014) in both girls and women. Myotube formation was not affected by exercise or group.

CONCLUSION

The systemic environment following one acute bout of low-impact moderate-intensity exercise in girls and women does not elicit osteoblast or myoblast activity in vitro. Differences in myoblast and osteoblast proliferation between girls and women may be influenced by maturation.

The Effects of Serum Removal on Gene Expression and Morphological Plasticity Markers in Differentiated SH-SY5Y Cells

Despite the widespread use of the SH-SY5Y human neuroblastoma cell line in modeling human neurons in vitro, protocols for growth, differentiation and experimentation differ considerably across the literature. Many studies fully differentiate SH-SY5Y cells before experimentation, to investigate plasticity measures in a mature, human neuronal-like cell model. Prior to experimentation, serum is often removed from cell culture media, to arrest the cell growth cycle and synchronize cells. However, the exact effect of this serum removal before experimentation on mature, differentiated SH-SY5Y cells has not yet been described. In studies using differentiated SH-SY5Y cells, any effect of serum removal on plasticity markers may influence results. The aim of the current study was to systematically characterize, in differentiated, neuronal-like SH-SY5Y cells, the potentially confounding effects of complete serum removal in terms of morphological and gene expression markers of plasticity. We measured changes in commonly used morphological markers and in genes related to neuroplasticity and synaptogenesis, particularly in the BDNF-TrkB signaling pathway. We found that complete serum removal from already differentiated SH-SY5Y cells increases neurite length, neurite branching, and the proportion of cells with a primary neurite, as well as proportion of βIII-Tubulin and MAP2 expressing cells. Gene expression results also indicate increased expression of PSD95 and NTRK2 expression 24 h after serum removal. We conclude that serum deprivation in differentiated SH-SY5Y cells affects morphology and gene expression and can potentially confound plasticity-related outcome measures, having significant implications for experimental design in studies using differentiated SH-SY5Y cells as a model of human neurons.

Cell Proliferation Is Strongly Associated with the Treatment Conditions of an ER Stress Inducer New Anti-Melanoma Drug in Melanoma Cell Lines

HA15 is a new anti-melanoma drug that triggers endoplasmic reticulum (ER) stress and causes deleterious effects on melanoma cell viability due to autophagy and apoptosis, regardless of driver mutations or drug resistance. In this study, we investigated the effect of HA15 on the viability/proliferation of BRAFV600E-mutant melanoma cells using different culture conditions. In contrast to the published data, we did not detect significant melanoma cell death under normal culture conditions using HA15 treatment. Indeed, only cells that were cultured under long-term starvation conditions were sensitive to the drug. Quantitative measurements of ER stress and autophagy markers showed that the compound HA15 does not trigger stress alone but synergistically enhances ER stress under starvation conditions. Importantly, we observed that the viability of normal melanocytes decreased significantly with treatment, even at low HA15 concentrations. Finally yet importantly, we were able to generate HA15-resistant cell lines, which failed by Cerezo et al. In summary, HA15 only influences the viability of cells that are starved for several hours before and during treatment. However, this in vitro setting is far from the in vivo conditions. In addition, our data clearly show that melanoma cells can acquire HA15 resistance. Further studies are needed to prove that HA15 is an effective anti-cancer agent.

Cell-cycle-gated feedback control mediates desensitization to interferon stimulation

Cells use molecular circuits to interpret and respond to extracellular cues, such as hormones and cytokines, which are often released in a temporally varying fashion. In this study, we combine microfluidics, time-lapse microscopy, and computational modeling to investigate how the type I interferon (IFN)-responsive regulatory network operates in single human cells to process repetitive IFN stimulation. We found that IFN-α pretreatments lead to opposite effects, priming versus desensitization, depending on input durations. These effects are governed by a regulatory network composed of a fast-acting positive feedback loop and a delayed negative feedback loop, mediated by upregulation of ubiquitin-specific peptidase 18 (USP18). We further revealed that USP18 upregulation can only be initiated at the G1/early S phases of cell cycle upon the treatment onset, resulting in heterogeneous and delayed induction kinetics in single cells. This cell cycle gating provides a temporal compartmentalization of feedback loops, enabling duration-dependent desensitization to repetitive stimulations.

Innate Immune Functions of Astrocytes are Dependent Upon Tumor Necrosis Factor-Alpha

Acute inflammation is a key feature of innate immunity that initiates clearance and repair in infected or damaged tissues. Alternatively, chronic inflammation is implicated in numerous disease processes. The contribution of neuroinflammation to the pathogenesis of neurological conditions, including infection, traumatic brain injury, and neurodegenerative diseases, has become increasingly evident. Potential drivers of such neuroinflammation include toll-like receptors (TLRs). TLRs confer a wide array of functions on different cell types in the central nervous system (CNS). Importantly, how TLR activation affects astrocyte functioning is unclear. In the present study, we examined the role of TLR2/4 signaling on various astrocyte functions (i.e., proliferation, pro-inflammatory mediator production, regulatory mechanisms, etc) by stimulating astrocytes with potent exogenous TLR2/4 agonist, bacterial lipopolysaccharide (LPS). Newborn astrocytes were derived from WT, Tnfα^−/−, Il1α^−/−/Il1β^−/−, and Tlr2^−/−/Tlr4^−/− mice as well as Sprague Dawley rats for all in vitro studies. LPS activated mRNA expression of different pro-inflammatory cytokines and chemokines in time- and concentration-dependent manners, and upregulated the proliferation of astrocytes based on increased ³H-thymidine update. Following LPS-mediated TLR2/4 activation, TNF-α and IL-1β self-regulated and modulated the expression of pro-inflammatory cytokines and chemokines. Polyclonal antibodies against TNF-α suppressed TLR2/4-mediated upregulation of astrocyte proliferation, supporting an autocrine/paracrine role of TNF-α on astrocyte proliferation. Astrocytes perform classical innate immune functions, which contradict the current paradigm that microglia are the main immune effector cells of the CNS. TNF-α plays a pivotal role in the LPS-upregulated astrocyte activation and proliferation, supporting their critical roles in in CNS pathogenesis.

In vitro induction of quiescence in isolated primary human myoblasts

Adult skeletal muscle stem cells, satellite cells, remain in an inactive or quiescent state in vivo under physiological conditions. Progression through the cell cycle, including activation of quiescent cells, is a tightly regulated process. Studies employing in vitro culture of satellite cells, primary human myoblasts (PHMs), necessitate isolation myoblasts from muscle biopsies. Further studies utilizing these cells should endeavour to represent their native in vivo characteristics as closely as possible, also considering variability between individual donors. This study demonstrates the approach of utilizing KnockOut™ Serum Replacement (KOSR)-supplemented culture media as a quiescence-induction media for 10 days in PHMs isolated and expanded from three different donors. Cell cycle analysis demonstrated that treatment resulted in an increase in G1 phase and decreased S phase proportions in all donors (p < 0.005). The proportions of cells in G1 and G2 phases differed in proliferating myoblasts when comparing donors (p < 0.05 to p < 0.005), but following KOSR treatment, the proportion of cells in G1 (p = 0.558), S (p = 0.606) and G2 phases (p = 0.884) were equivalent between donors. When cultured in the quiescence-induction media, expression of CD34 and Myf5 remained constant above > 98% over time from day 0 to day 10. In contrast activation (CD56), proliferation (Ki67) and myogenic marker MyoD decreased, indicated de-differentiation. Induction of quiescence was accompanied in all three clones by fold change in p21 mRNA greater than 3.5 and up to tenfold. After induction of quiescence, differentiation into myotubes was not affected. In conclusion, we describe a method to induce quiescence in PHMs from different donors.

What is Normalization? The Strategies Employed in Top-Down and Bottom-Up Proteome Analysis Workflows

The accurate quantification of changes in the abundance of proteins is one of the main applications of proteomics. The maintenance of accuracy can be affected by bias and error that can occur at many points in the experimental process, and normalization strategies are crucial to attempt to overcome this bias and return the sample to its regular biological condition, or normal state. Much work has been published on performing normalization on data post-acquisition with many algorithms and statistical processes available. However, there are many other sources of bias that can occur during experimental design and sample handling that are currently unaddressed. This article aims to cast light on the potential sources of bias and where normalization could be applied to return the sample to its normal state. Throughout we suggest solutions where possible but, in some cases, solutions are not available. Thus, we see this article as a starting point for discussion of the definition of and the issues surrounding the concept of normalization as it applies to the proteomic analysis of biological samples. Specifically, we discuss a wide range of different normalization techniques that can occur at each stage of the sample preparation and analysis process.

Stem cell factor and NSC87877 synergism enhances c-Kit mediated proliferation of human erythroid cells

The biological mechanisms underlying the effects of stem cell factor (SCF) and an inhibitor, NSC87877 (N) of the c-Kit negative regulator (SHP-1 and SHP-2) on cell proliferation are different. Therefore, we compared the cell's response to these two either alone or in combination in K562 cells. Binding of SCF (S) to c-Kit induces dimerization that activates its kinase activity. The activated c-Kit undergoes autophosphorylation at tyrosine residues that serve as a docking site for signal transduction molecules containing SH2 domains. Predominantly, the phosphotyrosine 568 (pY568) in Juxtamembrane (JM) region of c-Kit interacts with adaptor protein APS, Src family kinase, and SHP-2, while phosphotyrosine 570 (pY570) interacts with the SHP-1 and the adaptor protein Shc. The dephosphorylation of phosphotyrosine residues by SHP-1/SHP-2 leads to inhibition of c-Kit proliferative signaling. A chemical molecule, N is reported to inhibit the enzymatic activity of SHP-1/SHP-2, but its effect on c-Kit-mediated proliferation has not been studied yet. Thus, this work aims at examining the effect of the combination of S and N on cells growth as compared to individual treatment. The present study is performed with erythroleukemic K562 cells, chosen for its mRNA expression concerning the c-Kit, and SHP-1/SHP-2. Interestingly, proliferation assay showed that combination significantly increased proliferation when G₁ sorted K562 cells were used. These changes were significantly higher when K562 cells were initially treated with N followed by S treatment. Collectively, these results give mechanistic insight into the proliferation enhancement of bone marrow transplantation through the synergistic effect of S and N by inhibiting SHP-1/SHP-2. The study gives solid evidence that S and N combination can be used to enhance cell proliferation/growth.

3D Shape Modeling for Cell Nuclear Morphological Analysis and Classification

Quantitative analysis of morphological changes in a cell nucleus is important for the understanding of nuclear architecture and its relationship with pathological conditions such as cancer. However, dimensionality of imaging data, together with a great variability of nuclear shapes, presents challenges for 3D morphological analysis. Thus, there is a compelling need for robust 3D nuclear morphometric techniques to carry out population-wide analysis. We propose a new approach that combines modeling, analysis, and interpretation of morphometric characteristics of cell nuclei and nucleoli in 3D. We used robust surface reconstruction that allows accurate approximation of 3D object boundary. Then, we computed geometric morphological measures characterizing the form of cell nuclei and nucleoli. Using these features, we compared over 450 nuclei with about 1,000 nucleoli of epithelial and mesenchymal prostate cancer cells, as well as 1,000 nuclei with over 2,000 nucleoli from serum-starved and proliferating fibroblast cells. Classification of sets of 9 and 15 cells achieved accuracy of 95.4% and 98%, respectively, for prostate cancer cells, and 95% and 98% for fibroblast cells. To our knowledge, this is the first attempt to combine these methods for 3D nuclear shape modeling and morphometry into a highly parallel pipeline workflow for morphometric analysis of thousands of nuclei and nucleoli in 3D.

Mammalian Cell Division in 3D Matrices via Quantitative Confocal Reflection Microscopy

The study of how mammalian cell division is regulated in a 3D environment remains largely unexplored despite its physiological relevance and therapeutic significance. Possible reasons for the lack of exploration are the experimental limitations and technical challenges that render the study of cell division in 3D culture inefficient. Here, we describe an imaging-based method to efficiently study mammalian cell division and cell-matrix interactions in 3D collagen matrices. Cells labeled with fluorescent H2B are synchronized using the combination of thymidine blocking and nocodazole treatment, followed by a mechanical shake-off technique. Synchronized cells are then embedded into a 3D collagen matrix. Cell division is monitored using live-cell microscopy. The deformation of collagen fibers during and after cell division, which is an indicator of cell-matrix interaction, can be monitored and quantified using quantitative confocal reflection microscopy. The method provides an efficient and general approach to study mammalian cell division and cell-matrix interactions in a physiologically relevant 3D environment. This approach not only provides novel insights into the molecular basis of the development of normal tissue and diseases, but also allows for the design of novel diagnostic and therapeutic approaches.

Non-aggregated Aβ25-35 Upregulates Primary Astrocyte Proliferation In Vitro

Amyloid beta (Aβ) is a peptide cleaved from amyloid precursor protein that contributes to the formation of senile plaques in Alzheimer’s disease (AD). The relationship between Aβ and astrocyte proliferation in AD remains controversial. Despite pathological findings of increased astrocytic mitosis in AD brains, in vitro studies show an inhibitory effect of Aβ on astrocyte proliferation. In this study, we determined the effect of an active fragment of Aβ (Aβ_25-35) on the cell cycle progression of primary rat astrocytes. We found that Aβ_25-35 (0.3–1.0 μg/ml) enhanced astrocyte proliferation in vitro in a time- and concentration-dependent manner. Increased DNA synthesis by Aβ_25-35 was observed during the S phase of the astrocyte cell cycle, as indicated by proliferation kinetics and bromodeoxyuridine immunocytochemical staining. Aggregation of Aβ_25-35 abolished the upregulatory effect of Aβ on astrocyte proliferation. Further examination indicated that Aβ_25-35 affected astrocyte proliferation during early or mid-G₁ phase but had no effect on DNA synthesis at the peak of S phase. These results provide insight into the relationship between Aβ_25-35 and astrocyte cell cycling in AD.

Serum from CCl4-induced acute rat injury model induces differentiation of ADSCs towards hepatic cells and reduces liver fibrosis

Cellular therapies hold promise to alleviate liver diseases. This study explored the potential of allogenic serum isolated from rat with acute CCl₄ injury to differentiate adipose derived stem cells (ADSCs) towards hepatic lineage. Acute liver injury was induced by CCl₄ which caused significant increase in serum levels of VEGF, SDF1α and EGF. ADSCs were preconditioned with 3% serum isolated from normal and acute liver injury models. ADSCs showed enhanced expression of hepatic markers (AFP, albumin, CK8 and CK19). These differentiated ADSCs were transplanted intra-hepatically in CCl₄-induced liver fibrosis model. After one month of transplantation, fibrosis and liver functions (alkaline phosphatase, ALAT and bilirubin) showed marked improvement in acute injury group. Elevated expression of hepatic (AFP, albumin, CK 18 and HNF4a) and pro survival markers (PCNA and VEGF) and improvement in liver architecture as deduced from results of alpha smooth muscle actin, Sirius red and Masson's trichome staining was observed.

Naringenin inhibits transforming growth factor-β1-induced cardiac fibroblast proliferation and collagen synthesis via G0/G1 arrest

The Traditional Chinese Medicine naringenin (NRG) has a number of biological effects, including anti-inflammatory, anti-oxidative, anti-tumor and anti-atherosclerotic effects. However, the mechanism underlying its effects remains unclear. The aim of the present study is to investigate the role and mechanism of NRG on proliferation and collagen synthesis of cardiac fibroblasts (CFs) induced by transforming growth factor β1 (TGF-β1). Firstly, proliferation and collagen synthesis in CFs subjected to TGF-β1 was assessed subsequent to the consumption of NRG or control treatment. Additionally, the cell cycle of different groups and the roles of cyclins and cyclin-dependent kinases (CDKs) in NRG treatment of CFs were detected. In the present study, it was revealed that treatment of CFs with NRG resulted in attenuated fibroblast α-smooth muscle actin expression, deceased proliferation and collagen synthesis when compared with a TGF-β1 stimulus. Additionally, it was demonstrated that cell population of CFs treated with NRG in the S-phase became smaller whereas that of CFs in the G0/G1-phase increased when compared with the TGF-β1 group. Mechanistically, the expression of cyclin D1-CDK4/6 and cyclin E2-CDK2 were inhibited in the NRG treatment group. These results illustrated that the protective effects of NRG on proliferation and collagen synthesis of CFs were at least in part due to G0/G1 arrest. Therefore, NRG may become a novel strategy for treating cardiac fibrosis in the future.

Cetuximab Prevents Methotrexate-Induced Cytotoxicity in Vitro through Epidermal Growth Factor Dependent Regulation of Renal Drug Transporters

The combination of methotrexate with epidermal growth factor receptor (EGFR) recombinant antibody, cetuximab, is currently being investigated in treatment of head and neck carcinoma. As methotrexate is cleared by renal excretion, we studied the effect of cetuximab on renal methotrexate handling. We used human conditionally immortalized proximal tubule epithelial cells overexpressing either organic anion transporter 1 or 3 (ciPTEC-OAT1/ciPTEC-OAT3) to examine OAT1 and OAT3, and the efflux pumps breast cancer resistance protein (BCRP), multidrug resistance protein 4 (MRP4), and P-glycoprotein (P-gp) in methotrexate handling upon EGF or cetuximab treatment. Protein kinase microarrays and knowledge-based pathway analysis were used to predict EGFR-mediated transporter regulation. Cytotoxic effects of methotrexate were evaluated using the dimethylthiazol bromide (MTT) viability assay. Methotrexate inhibited OAT-mediated fluorescein uptake and decreased efflux of Hoechst33342 and glutathione-methylfluorescein (GS-MF), which suggested involvement of OAT1/3, BCRP, and MRP4 in transepithelial transport, respectively. Cetuximab reversed the EGF-increased expression of OAT1 and BCRP as well as their membrane expressions and transport activities, while MRP4 and P-gp were increased. Pathway analysis predicted cetuximab-induced modulation of PKC and PI3K pathways downstream EGFR/ERBB2/PLCg. Pharmacological inhibition of ERK decreased expression of OAT1 and BCRP, while P-gp and MRP4 were increased. AKT inhibition reduced all transporters. Exposure to methotrexate for 24 h led to a decreased viability, an effect that was reversed by cetuximab. In conclusion, cetuximab downregulates OAT1 and BCRP while upregulating P-gp and MRP4 through an EGFR-mediated regulation of PI3K-AKT and MAPKK-ERK pathways. Consequently, cetuximab attenuates methotrexate-induced cytotoxicity, which opens possibilities for further research into nephroprotective comedication therapies.

Flagellar Synchronization Is a Simple Alternative to Cell Cycle Synchronization for Ciliary and Flagellar Studies

Cilia and flagella are highly conserved antenna-like organelles that found in nearly all mammalian cell types. They perform sensory and motile functions contributing to numerous physiological and developmental processes. Defects in their assembly and function are implicated in a wide range of human diseases ranging from retinal degeneration to cancer. Chlamydomonas reinhardtii is an algal model system for studying mammalian cilium formation and function. Here, we report a simple synchronization method that allows detection of small changes in ciliary length by minimizing variability in the population. We find that this method alters the key relationship between cell size and the amount of protein accumulated for flagellar growth. This provides a rapid alternative to traditional methods of cell synchronization for uncovering novel regulators of cilia.

The unicellular green alga Chlamydomonas reinhardtii is an ideal model organism for studies of ciliary function and assembly. In assays for biological and biochemical effects of various factors on flagellar structure and function, synchronous culture is advantageous for minimizing variability. Here, we have characterized a method in which 100% synchronization is achieved with respect to flagellar length but not with respect to the cell cycle. The method requires inducing flagellar regeneration by amputation of the entire cell population and limiting regeneration time. This results in a maximally homogeneous distribution of flagellar lengths at 3 h postamputation. We found that time-limiting new protein synthesis during flagellar synchronization limits variability in the unassembled pool of limiting flagellar protein and variability in flagellar length without affecting the range of cell volumes. We also found that long- and short-flagella mutants that regenerate normally require longer and shorter synchronization times, respectively. By minimizing flagellar length variability using a simple method requiring only hours and no changes in media, flagellar synchronization facilitates the detection of small changes in flagellar length resulting from both chemical and genetic perturbations in Chlamydomonas. This method increases our ability to probe the basic biology of ciliary size regulation and related disease etiologies.

IMPORTANCE Cilia and flagella are highly conserved antenna-like organelles that found in nearly all mammalian cell types. They perform sensory and motile functions contributing to numerous physiological and developmental processes. Defects in their assembly and function are implicated in a wide range of human diseases ranging from retinal degeneration to cancer. Chlamydomonas reinhardtii is an algal model system for studying mammalian cilium formation and function. Here, we report a simple synchronization method that allows detection of small changes in ciliary length by minimizing variability in the population. We find that this method alters the key relationship between cell size and the amount of protein accumulated for flagellar growth. This provides a rapid alternative to traditional methods of cell synchronization for uncovering novel regulators of cilia.

APOBEC3A damages the cellular genome during DNA replication

The human APOBEC3 family of DNA-cytosine deaminases comprises 7 members (A3A-A3H) that act on single-stranded DNA (ssDNA). The APOBEC3 proteins function within the innate immune system by mutating DNA of viral genomes and retroelements to restrict infection and retrotransposition. Recent evidence suggests that APOBEC3 enzymes can also cause damage to the cellular genome. Mutational patterns consistent with APOBEC3 activity have been identified by bioinformatic analysis of tumor genome sequences. These mutational signatures include clusters of base substitutions that are proposed to occur due to APOBEC3 deamination. It has been suggested that transiently exposed ssDNA segments provide substrate for APOBEC3 deamination leading to mutation signatures within the genome. However, the mechanisms that produce single-stranded substrates for APOBEC3 deamination in mammalian cells have not been demonstrated. We investigated ssDNA at replication forks as a substrate for APOBEC3 deamination. We found that APOBEC3A (A3A) expression leads to DNA damage in replicating cells but this is reduced in quiescent cells. Upon A3A expression, cycling cells activate the DNA replication checkpoint and undergo cell cycle arrest. Additionally, we find that replication stress leaves cells vulnerable to A3A-induced DNA damage. We propose a model to explain A3A-induced damage to the cellular genome in which cytosine deamination at replication forks and other ssDNA substrates results in mutations and DNA breaks. This model highlights the risk of mutagenesis by A3A expression in replicating progenitor cells, and supports the emerging hypothesis that APOBEC3 enzymes contribute to genome instability in human tumors.

Quercetin-induced miR-200b-3p regulates the mode of self-renewing divisions in pancreatic cancer

BACKGROUND

Cancer stem cells are suggested to contribute to the extremely poor prognosis of pancreatic ductal adenocarcinoma and dysregulation of symmetric and asymmetric stem cell division may be involved. Anticancer benefits of phytochemicals like the polyphenol quercetin, present in many fruits, nuts and vegetables, could be expedited by microRNAs, which orchestrate cell-fate decisions and tissue homeostasis. The mechanisms regulating the division mode of cancer stem cells in relation to phytochemical-induced microRNAs are poorly understood.

METHODS

Patient-derived pancreas tissue and 3 established pancreatic cancer cell lines were examined by immunofluorescence and time-lapse microscopy, microRNA microarray analysis, bioinformatics and computational analysis, qRT-PCR, Western blot analysis, self-renewal and differentiation assays.

RESULTS

We show that symmetric and asymmetric division occurred in patient tissues and in vitro, whereas symmetric divisions were more extensive. By microarray analysis, bioinformatics prediction and qRT-PCR, we identified and validated quercetin-induced microRNAs involved in Notch signaling/cell-fate determination. Further computational analysis distinguished miR-200b-3p as strong candidate for cell-fate determinant. Mechanistically, miR-200b-3p switched symmetric to asymmetric cell division by reversing the Notch/Numb ratio, inhibition of the self-renewal and activation of the potential to differentiate to adipocytes, osteocytes and chondrocytes. Low miR-200b-3p levels fostered Notch signaling and promoted daughter cells to become symmetric while high miR-200b-3p levels lessened Notch signaling and promoted daughter cells to become asymmetric.

CONCLUSIONS

Our findings provide a better understanding of the cross talk between phytochemicals, microRNAs and Notch signaling in the regulation of self-renewing cancer stem cell divisions.

Histone methyltransferase Setd2 is critical for the proliferation and differentiation of myoblasts

Skeletal muscle cell proliferation and differentiation are tightly regulated. Epigenetic regulation is a major component of the regulatory mechanism governing these processes. Histone modification is part of the epigenetic code used for transcriptional regulation of chromatin through the establishment of an active or repressive state for genes involved in myogenesis in a temporal manner. Here, we uncovered the function of SET domain containing 2 (Setd2), an essential histone 3 lysine 36 trimethyltransferase, in regulating the proliferation and differentiation of myoblasts. Setd2 was silenced in the skeletal muscle myoblast cell line, C2C12, using the CRISPR/CAS9 system. The mutant cells exhibited defect in myotube formation. The myotube formation marker, myosin heavy chain (MHC), was downregulated earlier in Setd2 silenced cells compared to wild-type myoblasts during differentiation. The deficiency in Setd2 also resulted in repression of Myogenin (MyoG) expression, a key myogenic regulator during differentiation. In addition to the myoblast differentiation defect, decreased proliferation rate with significantly reduced levels of histone 3 phosphorylation, indicative of cell proliferation defect, were observed in the Setd2 silenced cells; suggesting an impaired proliferation phenotype. Furthermore, compromised G1/S- and G2/M-phase transition and decreased expression levels of major regulators of cell cycle G1/S checkpoints, cyclin D1, CDK4, CDK6, and cyclin E2 were detected in Setd2 silenced cells. Consistent with the cell cycle arrested phenotype, cyclin-dependent kinase inhibitor p21 was upregulated in Setd2 silenced cells. Together, this study demonstrates an essential role of Setd2 in myoblast proliferation and differentiation, and uncovers Setd2-mediated molecular mechanism through regulating MyoG and p21.

Chemically Induced Cell Cycle Arrest in Perfusion Cell Culture

In contrast to most present methods, continuous imaging of live cells would require full automation in each processing step. As an integrated system that would meet all requirements does not exist, we have established a long-term scanning-perfusion platform that: (a) replaces old medium with fresh one, (b) bypasses physical contact with the cell culture during continuous cell growth, (c) provides uninterrupted photomicrography of single cells, and (d) secures near physiological conditions and sterility up to several weeks. The system was validated by synchronizing cells using serum starvation and butyrate-induced cell cycle arrest of HaCaT cells.

Trypanosoma cruzi induces cellular proliferation in the trophoblastic cell line BeWo

Congenital transmission of Trypanosoma cruzi (T. cruzi) is partially responsible for the progressive globalization of Chagas disease. During congenital transmission the parasite must cross the placental barrier where the trophoblast, a continuous renewing epithelium, is the first tissue in contact with the parasite. The trophoblast turnover implies cellular proliferation, differentiation and apoptotic cell death. The epithelial turnover is considered part of innate immunity. We previously demonstrated that T. cruzi induces cellular differentiation and apoptosis in this tissue. Here we demonstrate that T. cruzi induces cellular proliferation in a trophoblastic cell line. We analyzed the cellular proliferation in BeWo cells by determining DNA synthesis by BrdU incorporation assays, mitotic index, cell cycle analysis by flow cytometry, as well as quantification of nucleolus organizer regions by histochemistry and expression of the proliferation markers PCNA and Ki67 by Western blotting and/or immunofluorescence. Additionally, we determined the ERK1/2 MAPK pathway activation by the parasite by Western blotting.

Periodicity of nuclear morphology in human fibroblasts

MOTIVATION

Morphology of the cell nucleus has been used as a key indicator of disease state and prognosis, but typically without quantitative rigor. It is also not well understood how nuclear morphology varies with time across different genetic backgrounds in healthy cells. To help answer these questions we measured the size and shape of nuclei in cell-cycle-synchronized primary human fibroblasts from 6 different individuals at 32 time points over a 75 hour period.

RESULTS

The nucleus was modeled as an ellipsoid and its dynamics analyzed. Shape and volume changed significantly over this time. Two prominent frequencies were found in the 6 individuals: a 17 hour period consistent with the cell cycle and a 26 hour period. Our findings suggest that the shape of the nucleus changes over time and thus any time-invariant shape property may provide a misleading characterization of cellular populations at different phases of the cell cycle. The proposed methodology provides a general method to analyze morphological change using multiple time points even for non-live-cell experiments.

Differential and kinetic effects of cell cycle inhibitors on neoplastic and primary astrocytes

Alterations in cell cycle regulation underlie the unrestricted growth of neoplastic astrocytes. Chemotherapeutic interventions of gliomas have poor prognostic outcomes due to drug resistance and drug toxicity. Here, we examined the in vitro growth kinetics of C6 glioma (C6G) cells and primary astrocytes and their responses to 2 phase-specific inhibitors, lovastatin and hydroxyurea. C6G cells demonstrated a shorter G₁ phase and an earlier peak of DNA synthesis in S phase than primary astrocytes. As C6G cells and primary astrocytes re-entered the cell cycle in the presence of lovastatin or hydroxyurea, they exhibited different sensitivities to the inhibitory effects of these agents, as measured by [³H]-thymidine incorporation. Compared to primary astrocytes, C6G cells were more sensitive to lovastatin, but less sensitive to hydroxyurea. Studies using 2 different paradigms of exposure uncovered dramatic differences in the kinetics of DNA synthesis inhibition by these 2 agents in C6G cells and primary astrocytes. One notable difference was the ability of C6G cells to more easily recover from the inhibitory effects of hydroxyurea following short exposure. Our results provide insight into C6 glioma drug resistance as well as the inhibitory effects of these 2 phase-specific inhibitors and their chemotherapeutic potential.

Silencing of Human CutC Gene (hCutC) Induces Apoptosis in HepG2 Cells

Copper is an essential microelement required for maintaining normal cell physiology. Copper transporter CutC is one of the six members of Cut family proteins, involved in prokaryotic copper homeostasis. Human homolog of CutC (hCutC) is an intracellular copper-binding protein with unknown physiological function. In the present study using HepG2 cells, we report the effects of hCutC knockdown on copper sensitivity and morphology of cells that ultimately leads to apoptosis. We silenced hCutC using specific small interfering RNA (siRNA), and its downregulation was confirmed by quantitative real-time PCR. Though there was no significant variation in total cellular copper as estimated by inductively coupled plasma-atomic emission spectrometry (ICP-AES), knockdown of hCutC caused an increase in sensitivity of HepG2 cells to copper loads when compared to control cells (studied by MTT-based cell viability assay). Morphological analysis by transmission electron microscopy (TEM) indicated onset of apoptosis in hCutC-silenced cells which was exacerbated upon copper treatment. Mitochondrial transmembrane potential (ΔΨm) assay and DNA fragmentation assay further ensured apoptosis occurring in cells upon hCutC silencing. The present study reveals copper induced damage in cells upon hCutC silencing and provides evidence for the role of hCutC protein in intracellular copper homeostasis.

Mutagenesis of Coronavirus nsp14 Reveals Its Potential Role in Modulation of the Innate Immune Response

Coronavirus (CoV) nonstructural protein 14 (nsp14) is a 60-kDa protein encoded by the replicase gene that is part of the replication-transcription complex. It is a bifunctional enzyme bearing 3'-to-5' exoribonuclease (ExoN) and guanine-N7-methyltransferase (N7-MTase) activities. ExoN hydrolyzes single-stranded RNAs and double-stranded RNAs (dsRNAs) and is part of a proofreading system responsible for the high fidelity of CoV replication. nsp14 N7-MTase activity is required for viral mRNA cap synthesis and prevents the recognition of viral mRNAs as "non-self" by the host cell. In this work, a set of point mutants affecting different motifs within the ExoN domain of nsp14 was generated, using transmissible gastroenteritis virus as a model of Alphacoronavirus Mutants lacking ExoN activity were nonviable despite being competent in both viral RNA and protein synthesis. A specific mutation within zinc finger 1 (ZF-C) led to production of a viable virus with growth and viral RNA synthesis kinetics similar to that of the parental virus. Mutant recombinant transmissible gastroenteritis virus (TGEV) ZF-C (rTGEV-ZF-C) caused decreased cytopathic effect and apoptosis compared with the wild-type virus and reduced levels of dsRNA accumulation at late times postinfection. Consequently, the mutant triggered a reduced antiviral response, which was confirmed by evaluating different stages of the dsRNA-induced antiviral pathway. The expression of beta interferon (IFN-β), tumor necrosis factor (TNF), and interferon-stimulated genes in cells infected with mutant rTGEV-ZF-C was reduced compared to the levels seen with the parental virus. Overall, our data revealed a potential role for CoV nsp14 in modulation of the innate immune response.

IMPORTANCE

The innate immune response is the first line of antiviral defense that culminates in the synthesis of interferon and proinflammatory cytokines to control viral replication. CoVs have evolved several mechanisms to counteract the innate immune response at different levels, but the role of CoV-encoded ribonucleases in preventing activation of the dsRNA-induced antiviral response has not been described to date. The introduction of a mutation in zinc finger 1 of the ExoN domain of nsp14 led to production of a virus that induced a weak antiviral response, most likely due to the accumulation of lower levels of dsRNA in the late phases of infection. These observations allowed us to propose a novel role for CoV nsp14 ExoN activity in counteracting the antiviral response, which could serve as a novel target for the design of antiviral strategies.

Two-way communication between the metabolic and cell cycle machineries: the molecular basis

The relationship between cellular metabolism and the cell cycle machinery is by no means unidirectional. The ability of a cell to enter the cell cycle critically depends on the availability of metabolites. Conversely, the cell cycle machinery commits to regulating metabolic networks in order to support cell survival and proliferation. In this review, we will give an account of how the cell cycle machinery and metabolism are interconnected. Acquiring information on how communication takes place among metabolic signaling networks and the cell cycle controllers is crucial to increase our understanding of the deregulation thereof in disease, including cancer.

Temporal Tracking of Cell Cycle Progression Using Flow Cytometry without the Need for Synchronization

This protocol describes a method to permit the tracking of cells through the cell cycle without requiring the cells to be synchronized. Achieving cell synchronization can be difficult for many cell systems. Standard practice is to block cell cycle progression at a specific stage and then release the accumulated cells producing a wave of cells progressing through the cycle in unison. However, some cell types find this block toxic resulting in abnormal cell cycling, or even mass death. Bromodeoxyuridine (BrdU) uptake can be used to track the cell cycle stage of individual cells. Cells incorporate this synthetic thymidine analog, while synthesizing new DNA during S phase. By providing BrdU for a brief period it is possible to mark a pool of cells that were in S phase while the BrdU was present. These cells can then be tracked through the remainder of the cell cycle and into the next round of replication, permitting the duration of the cell cycle phases to be determined without the need to induce a potentially toxic cell cycle block. It is also possible to determine and correlate the expression of both internal and external proteins during subsequent stages of the cell cycle. These can be used to further refine the assignment of cell cycle stage or assess effects on other cellular functions such as checkpoint activation or cell death.

Inflammatory factors in the circulation of patients with active rheumatoid arthritis stimulate osteoclastogenesis via endogenous cytokine production by osteoblasts

SUMMARY

The combination of cytokines present in the circulation of patients with active rheumatoid arthritis might contribute to the generalized bone loss that commonly occurs in these patients, by directly inhibiting osteoblast proliferation and differentiation, but especially by enhancing endogenous cytokine (i.e., receptor activator of nuclear factor-kappa B ligand (RANKL) and interleukin-6 (IL)-6) production by osteoblasts, thereby stimulating osteoclastogenesis.

INTRODUCTION

Generalized bone loss, as occurs in patients with rheumatoid arthritis (RA), is related to elevated levels of circulating cytokines. Individual cytokines have deleterious effects on proliferation and differentiation of osteoblast cell lines, but little is known about the effect of the interaction between inflammatory factors in the circulation of patients with active RA on human osteoblast function, including their communication towards other bone cells. We investigated whether serum from patients with active RA enhances cytokine production by osteoblasts, thereby effectively altering osteoblast-stimulated osteoclastogenesis.

METHODS

Serum was obtained from 20 patients with active RA (active RA sera) and from the same patients in clinical remission (remission RA sera). To determine osteoclastogenesis, RA serum-pretreated primary human osteoblast cultures were established in direct contact with human osteoclast precursors in the presence or absence of osteoprotegerin (OPG) or IL-6 inhibitor.

RESULTS

Compared to remission RA sera, active RA sera inhibited osteoblast proliferation and differentiation in vitro as demonstrated by a reduced DNA content and gene expression of KI-67, collagen type 1, osteopontin, and osteocalcin. Active RA sera inhibited OPG expression and enhanced RANKL and IL-6 expression but did not alter IL-8 expression in osteoblasts. IL-1β, IL-17, and tumor necrosis factor-α (TNF-α) expression were undetectable. In coculture, active RA sera treatment of osteoblasts stimulated while addition of OPG or IL-6 inhibitory antibodies significantly reduced the number of osteoclasts.

CONCLUSION

Active RA sera contain circulating factors, likely cytokines and chemokines, that might contribute to bone loss by directly inhibiting osteoblast proliferation and differentiation, but especially, these factors modulate endogenous cytokine production by osteoblasts, thereby affecting osteoclastogenesis.

Early induction of stress-associated Src activator/Homo sapiens chromosome 9 open reading frame 10 protein following photodynamic therapy

BACKGROUND

There are proteins, responsible for many basic cell functions (transmission of extracellular signals to cytoplasm or nucleus, cell growth, proliferation, migration, survival), which are activated and overexpressed in response to acute oxidative stress, especially tyrosine kinases. The oxidative stress-associated Src activator/Homo sapiens chromosome 9 open reading frame 10 protein (Ossa/C9orf10) protects cancer cells from oxidative stress-induced apoptosis by Src family kinases activation.

METHODS

In this study precursor of protoporphyrin IX, 5-aminolevulinic acid and its encapsulated form were used in treating MCF-7 human breast cancer cells. After light illumination, cells were collected at different time points and used for evaluation (immunocytochemistry, Western blot analysis) of expression of above proteins, c-Src and Ossa.

RESULTS

Our results showed that 5-aminolevulinic acid-mediated photodynamic therapy caused decrease of c-Src expression at 7h after irradiation. The strongest expression was observed at 24h after treatment. Encapsulated form of 5-aminolevulinic acid in terms of PDT caused similar changes of expression of c-Src protein. Furthermore, we observed strong Ossa expression at 7h after treatment in comparison to very low expression at time points 0, 18 and 24h.

CONCLUSION

We would like to emphasize that our results showed high expression of Ossa at early time interval after PDT, which was accompanied by a low expression of c-Src kinase, what could protect cancer cells from PDT through activation of c-Src in response to oxidative stress.

Manganese induces mitochondrial dynamics impairment and apoptotic cell death: a study in human Gli36 cells

Manganese (Mn) is an essential trace element due to its participation in many physiological processes. However, overexposure to this metal leads to a neurological disorder known as Manganism whose clinical manifestations and molecular mechanisms resemble Parkinson's disease. Several lines of evidence implicate astrocytes as an early target of Mn neurotoxicity being the mitochondria the most affected organelles. The aim of this study was to investigate the possible mitochondrial dynamics alterations in Mn-exposed human astrocytes. Therefore, we employed Gli36 cells which express the astrocytic markers GFAP and S100B. We demonstrated that Mn triggers the mitochondrial apoptotic pathway revealed by increased Bax/Bcl-2 ratio, by the loss of mitochondrial membrane potential and by caspase-9 activation. This apoptotic program may be in turn responsible of caspase-3/7 activation, PARP-1 cleavage, chromatin condensation and fragmentation. In addition, we determined that Mn induces deregulation in mitochondria-shaping proteins (Opa-1, Mfn-2 and Drp-1) expression levels in parallel with the disruption of the mitochondrial network toward to an exacerbated fragmentation. Since mitochondrial dynamics is altered in several neurodegenerative diseases, these proteins could become future targets to be considered in Manganism treatment.