Interactions between cytoskeletal networks

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Table of contents

Preface
Summary
Résumé
Abbreviations
List of figures
I. The cytoskeleton
I-1. Actin
I-1-1. Form and assembly
I-1-2. Different structures of actin
I-1-3. Post-translational modifications
I-2. Microtubule
I-2-1. Form and assembly
I-2-2. Post-translational modifications
I-3. Intermediate filaments
I-3-1. Structure of IF proteins
I-3-2. Assembly into filament
I-3-3. Classification of IF proteins
I-3-3-1. Differences between nuclear and cytoplasmic IFs
I-3-3-2. Different categories of IF proteins
I-3-3-3. Alteration and mutations
I-3-4. Post-translational modifications
I-3-4-1. Phosphorylation
I-3-4-2. Farnesylation, glycosylation, transglutamination
I-4. IFs in Astrocytes
I-4-1. Description of the astrocyte model
I-4-2. Different IFs present in Astrocytes
I-4-2-1. GFAP
I-4-2-2. Synemin
I-4-2-3. Nestin
I-4-2-4. Vimentin
I-4-3. IFs in cancer: focus on Glioblastoma
I-5. Cytoskeletal interactions
I-5-1. Interactions between cytoskeletal networks
I-5-2. Transport of IFs in the cell: interaction with cellular protein motors
I-5-3. A fully formed network of IFs interacts with actin and MT
I-6. Key messages
II. The mechanical functions of the cytoskeletal network
II-1. Actin and actomyosin
II-2. Microtubules
II-3. Intermediate filaments
II-3-1. Physical and mechanical properties of IFs
II-3-2. Structural role of IFs
II-3-2-1. At the tissue level
II-3-2-2. At the cell level
II-3-3. IFs involvement in signalling
II-4. Key messages
III. Mechanotransduction
III-1. Mechanotransduction definition
III-2. Substrate Rigidity
III-3. Mechanosensing at adhesive structures on different substrate rigidity
III-3-1. Mechanosensing at FAs
III-3-2. Mechanosensing at adherens junctions
III-4. Cytoskeletal network in mechanotransduction
III-4-1. Actin
III-4-1-1. Role of actin/actomyosin in mechanosensing
III-4-1-2. Impact of mechanotransduction on actin and forces
III-4-2. Microtubules
III-4-3. Intermediate filaments
III-5. Key messages
IV. Mechanotransduction at the nucleus
IV-1. The LINC complex connects the cytoskeleton to the nucleoplasm
IV-2. The cytoplasmic and nuclear cytoskeleton protect the nucleus from mechanical stress
IV-2-1. Lamins
IV-2-2. Actin cap
IV-2-3. Cytoplasmic Intermediate filaments
IV-3. Cytoskeleton and nucleus positioning
IV-4. Control of nuclear morphology
IV-5. Mechanotransduction induces changes in gene expression
IV-5-1. Effects of mechanical signals on chromatin
IV-5-2. Control of gene expression in response to mechanical tension
IV-6. Key messages
V. Objectives
V-1. What are the effects of mechanical cues on nuclear morphology and structure?
V-1-1. Does substrate rigidity affect the nucleus size and morphology?
V-1-2. Does substrate rigidity affect the chromatin status?
V-1-3. Does substrate rigidity affect the nuclear recruitment of transcription factor YAP?
V-1-4. Does geometrical constrain affect the nucleus morphology?
V-2. Is the IF network reorganised in response to mechanical cues?
V-2-1. Does IF organisation change with the substrate rigidity?
V-3. Do IFs mediate the effect of substrate rigidity on the nucleus?
V-4. Looking for effectors of IFs new partners
VI. Material and methods
VI-1. Cell culture
VI-2. Transfection
VI-3. Hydrogel substrates of different rigidities
VI-4. Micropatterns
VI-5. Immunofluorescence
VI-6. Immunoprecipitation
VI-7. Mass spectrometry
VI-8. Western Blotting
VI-9. Image analysis
VI-10. Quantification and statistical analyses
VII. Results
VII-1. Substrate rigidity affects the nucleus of astrocytes
VII-1-1. Substrate rigidity affects the size and shape of the nucleus but not its position within the cell
VII-1-2. YAP nuclear localisation in astrocytes
VII-1-3. Substrate rigidity affects histone post translational modifications
VII-2. IFs organisation is changing with the rigidity of the substrate
VII-2-1. IFs form a cage-like structure around the nucleus on stiff substrates
VII-2-2. Substrate rigidity affects the phosphorylation status of vimentin
VII-3. Decreased IF protein expression by siRNA
VII-4. IFs mediate some effect of the substrate rigidity on the nucleus
VII-4-1. Specific IFs affect the size and morphology of the nucleus on soft stiffness
VII-4-2. IFs protect the nucleus against nuclear blebbing
VII-4-3. IFs are responsible for the positioning within the cell on different rigidities
VII-4-4. Vimentin increases YAP localisation on soft substrate
VII-5. IFs affect the rigidity dependent changes in histone PTM
VII-6. Discovery of new interactors of IFs
VII-6-1. Mass spectrometry analyses of potential interactors
VII-6-2. Confirmation of interaction between IFs and HDAC6
VII-7. Key messages
VIII. Discussion
VIII-1. Substrate rigidity affects the nucleus
VIII-1-1. Substrate rigidity affects the size and the shape of the nucleus
VIII-1-2. Substrate rigidity affect the tension on the nucleus
VIII-1-3. Substrate rigidity affect the structure of the chromatin
VIII-2. The organisation of IFs is changing with rigidity
VIII-2-1. IFs organisation around the nucleus
VIII-2-2. Phosphorylation of vimentin makes the network more soluble
VIII-3. IFs mediate the effects of substrate rigidity on the nucleus
VIII-3-1. Lack of IFs changes the morphology of the nucleus depending on substrate rigidity
VIII-3-2. IFs protect the nucleus from blebbing
VIII-3-3. IFs keep the nucleus centred in the different rigidity
VIII-3-4. Lack of IFs affect the acetylation of histone H3 depending on the substrate rigidity
VIII-4. Geometrical constrain and the nucleus
VIII-5. HDAC6 interaction with IFs
IX. Perspective
Appendix 1
Appendix 2
Appendix 3
Appendix 4
Appendix 5
Publication: “Intermediate filaments”
X. Bibliography