scholarly journals The Golgi Protein GM130 Regulates Centrosome Morphology and Function

2008 ◽  
Vol 19 (2) ◽  
pp. 745-753 ◽  
Author(s):  
Andrew Kodani ◽  
Christine Sütterlin
Keyword(s):  
Mammalian Cells ◽  
Cell Cycle Progression ◽  
Human Cell Lines ◽  
Microtubule Organizing Center ◽  
Microtubule Organization ◽  
Cycle Progression ◽  
Multipolar Spindles ◽  
Organizing Center ◽  
Golgi Protein ◽  
And Function

The Golgi apparatus (GA) of mammalian cells is positioned in the vicinity of the centrosome, the major microtubule organizing center of the cell. The significance of this physical proximity for organelle function and cell cycle progression is only beginning to being understood. We have identified a novel function for the GA protein, GM130, in the regulation of centrosome morphology, position and function during interphase. RNA interference–mediated depletion of GM130 from five human cell lines revealed abnormal interphase centrosomes that were mispositioned and defective with respect to microtubule organization and cell migration. When GM130-depleted cells entered mitosis, they formed multipolar spindles, arrested in metaphase, and died. We also detected aberrant centrosomes during interphase and multipolar spindles during mitosis in ldlG cells, which do not contain detectable GM130. Although GA proteins have been described to regulate mitotic centrosomes and spindle formation, this is the first report of a role for a GA protein in the regulation of centrosomes during interphase.

scholarly journals MLL5 maintains spindle bipolarity by preventing aberrant cytosolic aggregation of PLK1

2016 ◽  
Vol 212 (7) ◽  
pp. 829-843 ◽  
Author(s):  
Wei Zhao ◽  
Jie Liu ◽  
Xiaoming Zhang ◽  
Lih-Wen Deng
Keyword(s):  
Chromosome Segregation ◽  
Cell Cycle Progression ◽  
Genomic Stability ◽  
Binding Motif ◽  
Wild Type ◽  
Microtubule Organizing Center ◽  
Cycle Progression ◽  
Molecular Studies ◽  
Organizing Center ◽  
Do So

Faithful chromosome segregation with bipolar spindle formation is critical for the maintenance of genomic stability. Perturbation of this process often leads to severe mitotic failure, contributing to tumorigenesis. MLL5 has been demonstrated to play vital roles in cell cycle progression and the maintenance of genomic stability. Here, we identify a novel interaction between MLL5 and PLK1 in the cytosol that is crucial for sustaining spindle bipolarity during mitosis. Knockdown of MLL5 caused aberrant PLK1 aggregation that led to acentrosomal microtubule-organizing center (aMTOC) formation and subsequent spindle multipolarity. Further molecular studies revealed that the polo-box domain (PBD) of PLK1 interacted with a binding motif on MLL5 (Thr887-Ser888-Thr889), and this interaction was essential for spindle bipolarity. Overexpression of wild-type MLL5 was able to rescue PLK1 mislocalization and aMTOC formation in MLL5-KD cells, whereas MLL5 mutants incapable of interacting with the PBD failed to do so. We thus propose that MLL5 preserves spindle bipolarity through maintaining cytosolic PLK1 in a nonaggregated form.

scholarly journals Microtubule Organization in Striated Muscle Cells

Cells ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 1395 ◽  
Author(s):  
Robert Becker ◽  
Marina Leone ◽  
Felix Engel
Keyword(s):  
Nuclear Envelope ◽  
Mammalian Cells ◽  
Cell Cycle Progression ◽  
Striated Muscle ◽  
Muscle Cells ◽  
Cell Types ◽  
Microtubule Organizing Center ◽  
Microtubule Organization ◽  
Cardiac Muscle Cells ◽  
Microtubule Networks

Distinctly organized microtubule networks contribute to the function of differentiated cell types such as neurons, epithelial cells, skeletal myotubes, and cardiomyocytes. In striated (i.e., skeletal and cardiac) muscle cells, the nuclear envelope acts as the dominant microtubule-organizing center (MTOC) and the function of the centrosome—the canonical MTOC of mammalian cells—is attenuated, a common feature of differentiated cell types. We summarize the mechanisms known to underlie MTOC formation at the nuclear envelope, discuss the significance of the nuclear envelope MTOC for muscle function and cell cycle progression, and outline potential mechanisms of centrosome attenuation.

scholarly journals LINC00963 affects the development of colorectal cancer via MiR-532-3p/HMGA2 axis

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Jinjun Ye ◽  
Jidong Liu ◽  
Tao Tang ◽  
Le Xin ◽  
Xing Bao ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Tumor Growth ◽  
Cell Cycle Progression ◽  
Bioinformatics Analysis ◽  
Scratch Test ◽  
Luciferase Assay ◽  
Migration And Invasion ◽  
Cycle Progression ◽  
Ki67 Expression ◽  
And Function

Abstract Background LINC00963 is high-expressed in various carcinomas, but its expression and function in colorectal cancer (CRC) have not been explored. This study explored the role and mechanism of LINC00963 in CRC. Methods The expression of LINC00963 in CRC and its relationship with prognosis were examined by starBase and survival analysis. The effects of LINC00963, miR-532-3p and HMGA2 on the biological characteristics and EMT-related genes of CRC cells were studied by RT-qPCR, CCK-8, clone formation experiments, flow cytometry, scratch test, Transwell, and Western blot. Xenograft assay and immunohistochemistry were performed to verify the effect of LINC00963 on tumor growth. The correlation among LINC00963, miR-532-3p, and HMGA2 was analyzed by bioinformatics analysis, luciferase assay, and Pearson test. Results LINC00963 was high-expressed in CRC, and this was associated with poor prognosis of CRC. Silencing LINC00963 inhibited the activity, proliferation, migration, and invasion of CRC cells, MMP-3 and MMP-9 expressions, moreover, it also blocked cell cycle progression, and inhibited tumor growth and Ki67 expression. However, overexpression of LINC00963 showed the opposite effects to silencing LINC00963. LINC00963 targeted miR-532-3p to regulate HMGA2 expression. Down-regulation of miR-532-3p promoted cell proliferation, migration and invasion, and expressions of MMP-3 and MMP-9, and knockdown of HMGA2 reversed the effect of miR-532-3p inhibitor. Up-regulation of miR-532-3p inhibited the biological functions of CRC cells, and overexpression of HMGA2 reversed the miR-532-3p mimic effect. Conclusion LINC00963 affects the development of CRC through the miR-532-3p/HMGA2 axis.

scholarly journals Evidence for rapid structural and functional changes of the melanophore microtubule-organizing center upon pigment movements

1979 ◽  
Vol 83 (3) ◽  
pp. 623-632 ◽  
Author(s):  
M Schliwa ◽  
U Euteneuer ◽  
W Herzog ◽  
K Weber
Keyword(s):  
Complete Removal ◽  
Cell System ◽  
The State ◽  
Microtubule Assembly ◽  
Microtubule Organizing Center ◽  
Functional Changes ◽  
Organizing Center ◽  
Pigment Distribution ◽  
And Function ◽  
In Cells

Melanophores of the angelfish, pterophyllum scalare, have previously been shown to display approximately 2,400 microtubules in cells wih pigment dispersed; these microtubules radiate from a presumptive organizing center, the central apparatus (CA), and their number is reduced to approximately 1,000 in the state with aggregated pigment (M. Schliwa and U. Euteneuer, 1978, J. Supramol. Struct. 8:177-190). In an attempt to elucidate the factors controlling this rapid reorganization of the microtubule apparatus, structure and function of the CA have been investigated under different physiological conditions. As a function of the state of pigment distribution, melanophores differ markedly with respect to CA organization. A complex of dense amorphous aggregates and associated fuzzy material, several micrometers in diameter, surrounds the centrioles in cells with pigment dispersed, and numerous microtubules emanate from this complex in a radial fashion. In the aggregated state, on the other hand, few microtubules are observed in the pericentiolar region, and the amount of fibrous material is greatly reduced. These changes in CA morphology as a function of the state of pigment distribution are associated with a marked difference in its capacity to initiatiate the assembly of microtubules from exogenous pure porcine brain tubulin in lysed cell preparations. After complete removal of preexisting microtubules, cells lysed in the dispersed state into a solution of 1-2 mg/ml pure tubulin have numerous microtubules associated with the CA in radial fashion, while cells lysed in the aggregated state nucleate the assembly of only a few microtubules. We conclude that it is the activity of the CA that basically regulates the expression of microtubules. This regulation is achieved through a variation in the capacity to initiate microtubule assembly. Increase or decrease in the amount of dense material, as readily observed in the cell system studied here, seems to be a morphologic expression of such a physiologic function.

Overexpression of kin17 protein disrupts nuclear morphology and inhibits the growth of mammalian cells

1999 ◽  
Vol 112 (19) ◽  
pp. 3215-3224 ◽  
Author(s):  
P. Kannouche ◽  
J.F. Angulo
Keyword(s):  
Dna Replication ◽  
Mammalian Cells ◽  
Cell Cycle Progression ◽  
Reca Protein ◽  
S Phase ◽  
Expression Vectors ◽  
Nuclear Morphology ◽  
Functional Domain ◽  
Genetic Response ◽  
Cycle Progression

UVC or ionizing radiation of mammalian cells elicits a complex genetic response that allows recovery and cell survival. Kin17 gene, which is highly conserved among mammals, is upregulated during this response. Kin17 gene encodes a 45 kDa protein which binds to DNA and presents a limited similarity with a functional domain of the bacterial RecA protein. Kin17 protein is accumulated in the nucleus of proliferating fibroblasts and forms intranuclear foci. Using expression vectors, we show that overexpression of kin17 protein inhibits cell-cycle progression into S phase. Our results indicate that growth inhibition correlates with disruption of the nuclear morphology which seems to modify the intranuclear network required during the early steps of DNA replication. We report that a mutant encoding a protein deleted from the central domain of kin17 protein enhanced these effects whereas the deletion of the C-terminal domain considerably reduced them. These mutants will be used to elucidate the molecular mechanism by which kin17 protein alters cell growth and DNA replication.

scholarly journals Overall Cdk activity modulates the DNA damage response in mammalian cells

2009 ◽  
Vol 187 (6) ◽  
pp. 773-780 ◽  
Author(s):  
Antonio Cerqueira ◽  
David Santamaría ◽  
Bárbara Martínez-Pastor ◽  
Miriam Cuadrado ◽  
Oscar Fernández-Capetillo ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Mammalian Cells ◽  
Cell Cycle Progression ◽  
Cyclin Dependent Kinase ◽  
Genome Maintenance ◽  
Cycle Progression ◽  
Damage Response ◽  
Dna Break ◽  
Specific Contribution

In response to DNA damage, cells activate a phosphorylation-based signaling cascade known as the DNA damage response (DDR). One of the main outcomes of DDR activation is inhibition of cyclin-dependent kinase (Cdk) activity to restrain cell cycle progression until lesions are healed. Recent studies have revealed a reverse connection by which Cdk activity modulates processing of DNA break ends and DDR activation. However, the specific contribution of individual Cdks to this process remains poorly understood. To address this issue, we have examined the DDR in murine cells carrying a defined set of Cdks. Our results reveal that genome maintenance programs of postreplicative cells, including DDR, are regulated by the overall level of Cdk activity and not by specific Cdks.

Pentose Phosphate Pathway in Disease and Therapy

2014 ◽  
Vol 995 ◽  
pp. 1-27 ◽  
Author(s):  
Mahbuba Rahman ◽  
M. Rubayet Hasan
Keyword(s):  
Metabolic Pathways ◽  
Cell Cycle Progression ◽  
Metabolic Diseases ◽  
Pentose Phosphate ◽  
Cycle Progression ◽  
Novel Drugs ◽  
Abnormal Cells ◽  
Living Organisms ◽  
And Function

Pentose phosphate (PP) pathway, which is ubiquitously present in all living organisms, is one of the major metabolic pathways associated with glucose metabolism. The most important functions of this pathway includes the generation of reducing equivalents in the form of NADPH for reductive biosynthesis, and production of ribose sugars for the biosynthesis of nucleotides, amino acids, and other macromolecules required by all living cells. Under normal conditions of growth, PP pathway is important for cell cycle progression, myelin formation, and the maintenance of the structure and function of brain, liver, cortex and other organs. Under diseased conditions, such as in cases of many metabolic, neurological or malignant diseases, pathological mechanisms augment due to defects in the PP pathway genes. Adoption of alternative metabolic pathways by cells that are metabolically abnormal, or malignant cells that are resistant to chemotherapeutic drugs often plays important roles in disease progression and severity. Accordingly, the PP pathway has been suggested to play critical roles in protecting cancer or abnormal cells by providing reduced environment, to protect cells from oxidative damage and generating structural components for nucleic acids biosynthesis. Novel drugs that targets one or more components of the PP pathway could potentially serve to overcome challenges associated with currently available therapeutic options for many metabolic and non-metabolic diseases. However, careful designing of drugs is critical that takes into the accounts of cell’s broader genomic, proteomic and metabolic contexts under consideration, in order to avoid undesirable side-effects. In this review, we discuss the role of PP pathway under normal and abnormal physiological conditions and the potential of the PP pathway as a target for new drug development to treat metabolic and non-metabolic diseases.

scholarly journals Distinct Cell Cycle Timing Requirements for Extracellular Signal-Regulated Kinase and Phosphoinositide 3-Kinase Signaling Pathways in Somatic Cell Mitosis

2002 ◽  
Vol 22 (20) ◽  
pp. 7226-7241 ◽  
Author(s):  
Elisabeth C. Roberts ◽  
Paul S. Shapiro ◽  
Theresa Stines Nahreini ◽  
Gilles Pages ◽  
Jacques Pouyssegur ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Cyclin B1 ◽  
Erk Pathway ◽  
Cycle Progression ◽  
Mitotic Entry ◽  
Extracellular Signal Regulated Kinase ◽  
Extracellular Signal ◽  
Phosphoinositide 3 Kinase ◽  
And Function

ABSTRACT Mitogen-activated protein (MAP) kinase and phosphoinositide 3-kinase (PI3K) pathways are necessary for cell cycle progression into S phase; however the importance of these pathways after the restriction point is poorly understood. In this study, we examined the regulation and function of extracellular signal-regulated kinase (ERK) and PI3K during G2/M in synchronized HeLa and NIH 3T3 cells. Phosphorylation and activation of both the MAP kinase kinase/ERK and PI3K/Akt pathways occur in late S and persist until the end of mitosis. Signaling was rapidly reversed by cell-permeable inhibitors, indicating that both pathways are continuously activated and rapidly cycle between active and inactive states during G2/M. The serum-dependent behavior of PI3K/Akt versus ERK pathway activation indicates that their mechanisms of regulation differ during G2/M. Effects of cell-permeable inhibitors and dominant-negative mutants show that both pathways are needed for mitotic progression. However, inhibiting the PI3K pathway interferes with cdc2 activation, cyclin B1 expression, and mitotic entry, whereas inhibiting the ERK pathway interferes with mitotic entry but has little effect on cdc2 activation and cyclin B1 and retards progression from metaphase to anaphase. Thus, our study provides novel evidence that ERK and PI3K pathways both promote cell cycle progression during G2/M but have different regulatory mechanisms and function at distinct times.

Immunoprobe Localization by Correlative Microscopy

2000 ◽  
Vol 6 (3) ◽  
pp. 195-201 ◽  
Author(s):  
Patricia G. Calarco
Keyword(s):  
Electron Microscopy ◽  
Light Microscopy ◽  
Ultrastructural Level ◽  
Correlative Microscopy ◽  
Microtubule Organizing Center ◽  
Large Size ◽  
Organizing Center ◽  
Gamma Tubulin ◽  
High Level ◽  
And Function

AbstractMammalian oocytes present challenges for optimal study by electron microscopy (EM) due to their high level of hydration, their large size, and their relatively undifferentiated cytoplasm. This is particularly true for immunoprobe localization which has led to a dependence on light microscopic (LM) techniques, such as immunofluorescence. This study presents correlative LM and EM data to describe an example of the failure of light microscopy to correctly predict the ultrastructure of one particular organelle. Immunoprobe localization of centrosome and microtubule organizing center (MTOC) antigens in the mammalian egg was made by immunofluorescence and post-embedding immuno-EM, with best EM results achieved in Lowicryl-embedded material. Centrosome and MTOC antigens were detected by 5051 and an antibody to gamma tubulin (γtubulin). Gamma tubulin is a highly conserved element of MTOCs in many species and, thus, is highly diagnostic for them; it is also considered essential for microtubule (MT) nucleation. Results indicate that prior to nuclear breakdown, 5051 antigens and γ-tubulin are found exclusively in a type of “organelle,” the multivesicular aggregate (MVA), that bears no resemblance to MTOCs at the ultrastructural level. Until recently, the MVA was considered an organelle without a known function, while standard MTOCs were presumed to be the entities that carry the proteins recognized by centrosome antibodies. LM localization of centrosomal antigens carried the presumption that standard MTOCs were the entities labeled. Whether or not other molecules are shown to co-localize to these MVA, the presence of γ-tubulin supports the contention that MVA, or their contents, serve as centrosomal precursors with a unique ultrastructure. Thus, dependence on LM techniques alone can lead to erroneous conclusions on organelle identity and function.

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