The Tubulin Code and Tubulin-Modifying Enzymes in Autophagy and Cancer

Microtubules are tubulin polymers that constitute the structure of eukaryotic cells. They control different cell functions that are often deregulated in cancer, such as cell shape, cell motility and the intracellular movement of organelles. Here, we focus on the crucial role of tubulin modifications in determining different cancer characteristics, including metastatic cell migration and therapy resistance. We also discuss the influence of microtubule modifications on the autophagic process—the cellular degradation pathway that influences cancer growth. We discuss findings showing that inducing microtubule modifications can be used as a means to kill cancer cells by inhibiting autophagy.

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Identifying loci required for follicular patterning using directed mosaics

Development ◽

10.1242/dev.125.12.2263 ◽

1998 ◽

Vol 125 (12) ◽

pp. 2263-2271 ◽

Cited By ~ 16

Author(s):

J.B. Duffy ◽

D.A. Harrison ◽

N. Perrimon

Keyword(s):

Cell Migration ◽

Cell Shape ◽

Egf Receptor ◽

Essential Genes ◽

Follicular Epithelium ◽

Loss Of Function ◽

Developmental Pathway ◽

Adult Tissues ◽

Phenotypic Screen

We have developed a ‘directed mosaic’ system in Drosophila by using the GAL4 system to control the expression of the yeast recombinase, FLP, in a spatial and temporal fashion. By directing FLP expression, we show that it is possible to efficiently and specifically target loss-of-function studies for vital loci to the developmental pathway of interest. A simple F1 adult phenotypic screen demonstrated that most adult tissues can be analyzed with this approach. Using GAL4 lines expressed during oogenesis, we have refined the system to examine the roles of vital loci in the development of the follicular epithelium. We have identified essential genes involved in egg chamber organization, cell migration and cell shape. Further, we have used this technique to gain insights into the role of the Drosophila EGF receptor pathway in establishing the egg axes. Finally, using different UAS-FLP, GAL4 and existing FRT lines, we have built stocks that permit the analysis of approximately 95% of the genome in follicular mosaics.

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The histone methyltransferase MLL is an upstream regulator of endothelial-cell sprout formation

Blood ◽

10.1182/blood-2006-08-039651 ◽

2006 ◽

Vol 109 (4) ◽

pp. 1472-1478 ◽

Cited By ~ 46

Author(s):

Florian Diehl ◽

Lothar Rössig ◽

Andreas M. Zeiher ◽

Stefanie Dimmeler ◽

Carmen Urbich

Keyword(s):

Gene Expression ◽

Endothelial Cells ◽

Cell Migration ◽

Endothelial Cell ◽

Umbilical Vein ◽

Underlying Mechanism ◽

Endothelial Cell Migration ◽

Cell Functions ◽

Sprout Formation

Abstract Posttranslational histone modification by acetylation or methylation regulates gene expression. Here, we investigated the role of the histone lysine methyltransferase MLL for angiogenic functions in human umbilical vein endothelial cells. Suppression of MLL expression by siRNA or incubation with the pharmacologic methyltransferase inhibitor 5′-deoxy-5′-(methylthio)adenosine significantly decreased endothelial-cell migration and capillary sprout formation, indicating that methyltransferase activity is required for proangiogenic endothelial-cell functions. Because the expression of homeodomain transcription factors (Hox) is regulated by MLL, we elucidated the role of Hox gene expression. MLL silencing was associated with reduced mRNA and protein expression of HoxA9 and HoxD3, whereas HoxB3, HoxB4, HoxB5, and HoxB9 were not altered. Overexpression of HoxA9 or HoxD3 partially compensated for impaired migration in MLL siRNA-transfected endothelial cells, suggesting that HoxA9 and HoxD3 both contribute to MLL-dependent migration. As a potential underlying mechanism, MLL siRNA down-regulated mRNA and protein levels of the HoxA9-dependent axon guidance factor EphB4. In contrast, MLL knockdown effects on capillary sprouting were not rescued by HoxA9 or HoxD3 overexpression, indicating that MLL affects additional targets required for 3-dimensional sprout formation. We conclude that MLL regulates endothelial-cell migration via HoxA9 and EphB4, whereas sprout formation requires MLL-dependent signals beyond HoxA9 and HoxD3.

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Autophagy a Close Relative of AML Biology

Biology ◽

10.3390/biology10060552 ◽

2021 ◽

Vol 10 (6) ◽

pp. 552

Author(s):

Carine Joffre ◽

Charlotte Ducau ◽

Laura Poillet-Perez ◽

Charly Courdy ◽

Véronique Mansat-De Mas

Keyword(s):

Degradation Pathway ◽

Close Relative ◽

Acid Oxidation ◽

Hematopoietic Stem ◽

Cell Functions ◽

Specific Degradation ◽

Proliferation In Vitro

Autophagy, which literally means “eat yourself”, is more than just a lysosomal degradation pathway. It is a well-known regulator of cellular metabolism and a mechanism implicated in tumor initiation/progression and therapeutic resistance in many cancers. However, whether autophagy acts as a tumor suppressor or promoter is still a matter of debate. In acute myeloid leukemia (AML), it is now proven that autophagy supports cell proliferation in vitro and leukemic progression in vivo. Mitophagy, the specific degradation of mitochondria through autophagy, was recently shown to be required for leukemic stem cell functions and survival, highlighting the prominent role of this selective autophagy in leukemia initiation and progression. Moreover, autophagy in AML sustains fatty acid oxidation through lipophagy to support mitochondrial oxidative phosphorylation (OxPHOS), a hallmark of chemotherapy-resistant cells. Nevertheless, in the context of therapy, in AML, as well as in other cancers, autophagy could be either cytoprotective or cytotoxic, depending on the drugs used. This review summarizes the recent findings that mechanistically show how autophagy favors leukemic transformation of normal hematopoietic stem cells, as well as AML progression and also recapitulates its ambivalent role in resistance to chemotherapies and targeted therapies.

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Microtubules in Polyomavirus Infection

Viruses ◽

10.3390/v12010121 ◽

2020 ◽

Vol 12 (1) ◽

pp. 121

Author(s):

Lenka Horníková ◽

Kateřina Bruštíková ◽

Jitka Forstová

Keyword(s):

Endoplasmic Reticulum ◽

Cell Shape ◽

Late Phase ◽

T Antigen ◽

Productive Infection ◽

Gene Products ◽

T Antigens ◽

Intracellular Movement ◽

Capsid Protein Vp1

Microtubules, part of the cytoskeleton, are indispensable for intracellular movement, cell division, and maintaining cell shape and polarity. In addition, microtubules play an important role in viral infection. In this review, we summarize the role of the microtubules’ network during polyomavirus infection. Polyomaviruses usurp microtubules and their motors to travel via early and late acidic endosomes to the endoplasmic reticulum. As shown for SV40, kinesin-1 and microtubules are engaged in the release of partially disassembled virus from the endoplasmic reticulum to the cytosol, and dynein apparently assists in the further disassembly of virions prior to their translocation to the cell nucleus—the place of their replication. Polyomavirus gene products affect the regulation of microtubule dynamics. Early T antigens destabilize microtubules and cause aberrant mitosis. The role of these activities in tumorigenesis has been documented. However, its importance for productive infection remains elusive. On the other hand, in the late phase of infection, the major capsid protein, VP1, of the mouse polyomavirus, counteracts T-antigen-induced destabilization. It physically binds microtubules and stabilizes them. The interaction results in the G2/M block of the cell cycle and prolonged S phase, which is apparently required for successful completion of the viral replication cycle.

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The photoreceptor cytoskeleton visualized

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100122800 ◽

1992 ◽

Vol 50 (1) ◽

pp. 480-481

Author(s):

Beth Burnside

Keyword(s):

Outer Segment ◽

Pigment Epithelium ◽

Retinal Pigment ◽

Cell Polarization ◽

Synaptic Proteins ◽

Cell Functions ◽

Vertebrate Photoreceptor ◽

Numerous Cell ◽

Turn Over

The vertebrate photoreceptor provides a drammatic example of cell polarization. Specialized to carry out phototransduction at its distal end and to synapse with retinal interneurons at its proximal end, this long slender cell has a uniquely polarized morphology which is reflected in a similarly polarized cytoskeleton. Membranes bearing photopigment are localized in the outer segment, a modified sensory cilium. Sodium pumps which maintain the dark current critical to photosensory transduction are anchored along the inner segment plasma membrane between the outer segment and the nucleus.Proximal to the nucleus is a slender axon terminating in specialized invaginating synapses with other neurons of the retina. Though photoreceptor diameter is only 3-8u, its length from the tip of the outer segment to the synapse may be as great as 200μ. This peculiar linear cell morphology poses special logistical problems and has evoked interesting solutions for numerous cell functions. For example, the outer segment membranes turn over by means of a unique mechanism in which new disks are continuously added at the proximal base of the outer segment, while effete disks are discarded at the tip and phagocytosed by the retinal pigment epithelium. Outer segment proteins are synthesized in the Golgi near the nucleus and must be transported north through the inner segment to their sites of assembly into the outer segment, while synaptic proteins must be transported south through the axon to the synapse.The role of the cytoskeleton in photoreceptor motile processes is being intensely investigated in several laboratories.

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Extracellular matrix: the gatekeeper of tumor angiogenesis

Biochemical Society Transactions ◽

10.1042/bst20190653 ◽

2019 ◽

Vol 47 (5) ◽

pp. 1543-1555 ◽

Cited By ~ 10

Author(s):

Maurizio Mongiat ◽

Simone Buraschi ◽

Eva Andreuzzi ◽

Thomas Neill ◽

Renato V. Iozzo

Keyword(s):

Extracellular Matrix ◽

Tumor Angiogenesis ◽

Signaling Cascades ◽

Cancer Growth ◽

Cell Behavior ◽

Metastatic Progression ◽

Surface Receptors ◽

The Matrix ◽

Multiple Signaling

Abstract The extracellular matrix is a network of secreted macromolecules that provides a harmonious meshwork for the growth and homeostatic development of organisms. It conveys multiple signaling cascades affecting specific surface receptors that impact cell behavior. During cancer growth, this bioactive meshwork is remodeled and enriched in newly formed blood vessels, which provide nutrients and oxygen to the growing tumor cells. Remodeling of the tumor microenvironment leads to the formation of bioactive fragments that may have a distinct function from their parent molecules, and the balance among these factors directly influence cell viability and metastatic progression. Indeed, the matrix acts as a gatekeeper by regulating the access of cancer cells to nutrients. Here, we will critically evaluate the role of selected matrix constituents in regulating tumor angiogenesis and provide up-to-date information concerning their primary mechanisms of action.

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The role of DUBs in the post-translational control of cell migration

Essays in Biochemistry ◽

10.1042/ebc20190022 ◽

2019 ◽

Vol 63 (5) ◽

pp. 579-594 ◽

Cited By ~ 2

Author(s):

Guillem Lambies ◽

Antonio García de Herreros ◽

Víctor M. Díaz

Keyword(s):

Cell Migration ◽

Translational Control ◽

Epithelial To Mesenchymal Transition ◽

Extracellular Matrix Remodeling ◽

Matrix Remodeling ◽

Mesenchymal Transition ◽

Tgfβ Receptors ◽

Fundamental Process ◽

Multistep Process

Abstract Cell migration is a multifactorial/multistep process that requires the concerted action of growth and transcriptional factors, motor proteins, extracellular matrix remodeling and proteases. In this review, we focus on the role of transcription factors modulating Epithelial-to-Mesenchymal Transition (EMT-TFs), a fundamental process supporting both physiological and pathological cell migration. These EMT-TFs (Snail1/2, Twist1/2 and Zeb1/2) are labile proteins which should be stabilized to initiate EMT and provide full migratory and invasive properties. We present here a family of enzymes, the deubiquitinases (DUBs) which have a crucial role in counteracting polyubiquitination and proteasomal degradation of EMT-TFs after their induction by TGFβ, inflammatory cytokines and hypoxia. We also describe the DUBs promoting the stabilization of Smads, TGFβ receptors and other key proteins involved in transduction pathways controlling EMT.

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