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IFT88 influences chondrocyte actin organization and biomechanics

IFT88 influences chondrocyte actin organization and biomechanics
IFT88 influences chondrocyte actin organization and biomechanics
Objectives: primary cilia are microtubule based organelles which control a variety of signalling pathways important in cartilage development, health and disease. This study examines the role of the intraflagellar transport (IFT) protein, IFT88, in regulating fundamental actin organisation and mechanics in articular chondrocytes.

Methods: the study used an established chondrocyte cell line with and without hypomorphic mutation of IFT88 (IFT88orpk). Confocal microscopy was used to quantify F-actin and myosin IIB organisation. Viscoelastic cell and actin cortex mechanics were determined using micropipette aspiration with actin dynamics visualised in live cells transfected with LifeACT-GFP.

Results: IFT88orpk cells exhibited a significant increase in acto-myosin stress fibre organisation relative to wild-type (WT) cells in monolayer and an altered response to cytochalasin D. Rounded IFT88orpk cells cultured in suspension exhibited reduced cortical actin expression with reduced cellular equilibrium modulus. Micropipette aspiration resulted in reduced membrane bleb formation in IFT88orpk cells. Following membrane blebbing, IFT88orpk cells exhibited slower reformation of the actin cortex. IFT88orpk cells showed increased actin deformability and reduced cortical tension confirming that IFT regulates actin cortex mechanics. The reduced cortical tension is also consistent with the reduced bleb formation.

Conclusions: this study demonstrates for the first time that the ciliary protein IFT88 regulates fundamental actin organisation and the stiffness of the actin cortex leading to alterations in cell deformation, mechanical properties and blebbing in an IFT88 chondrocyte cell line. This adds to the growing understanding of the role of primary cilia and IFT in regulating cartilage biology.
1063-4584
544-554
Wang, Z.
fe914552-33f1-4f0a-b8a1-52b82e8cb89e
Wann, A.K.T.
f1b0ea2f-dc8a-4588-a9d8-ae462ed0a993
Thompson, C.L.
8fb9d181-0b59-45b7-91ba-07d6fe6f1e8e
Hassen, A.
3259f37f-6975-4680-a8c3-8676210ca2ff
Wang, W.
8534fc2f-5969-40ab-aff5-96c97efaa922
Knight, M.M.
da926606-b5ef-48cb-8db8-8e4ddb85ed07
Wang, Z.
fe914552-33f1-4f0a-b8a1-52b82e8cb89e
Wann, A.K.T.
f1b0ea2f-dc8a-4588-a9d8-ae462ed0a993
Thompson, C.L.
8fb9d181-0b59-45b7-91ba-07d6fe6f1e8e
Hassen, A.
3259f37f-6975-4680-a8c3-8676210ca2ff
Wang, W.
8534fc2f-5969-40ab-aff5-96c97efaa922
Knight, M.M.
da926606-b5ef-48cb-8db8-8e4ddb85ed07

Wang, Z., Wann, A.K.T., Thompson, C.L., Hassen, A., Wang, W. and Knight, M.M. (2016) IFT88 influences chondrocyte actin organization and biomechanics. Osteoarthritis and Cartilage, 24 (3), 544-554. (doi:10.1016/J.JOCA.2015.10.003).

Record type: Article

Abstract

Objectives: primary cilia are microtubule based organelles which control a variety of signalling pathways important in cartilage development, health and disease. This study examines the role of the intraflagellar transport (IFT) protein, IFT88, in regulating fundamental actin organisation and mechanics in articular chondrocytes.

Methods: the study used an established chondrocyte cell line with and without hypomorphic mutation of IFT88 (IFT88orpk). Confocal microscopy was used to quantify F-actin and myosin IIB organisation. Viscoelastic cell and actin cortex mechanics were determined using micropipette aspiration with actin dynamics visualised in live cells transfected with LifeACT-GFP.

Results: IFT88orpk cells exhibited a significant increase in acto-myosin stress fibre organisation relative to wild-type (WT) cells in monolayer and an altered response to cytochalasin D. Rounded IFT88orpk cells cultured in suspension exhibited reduced cortical actin expression with reduced cellular equilibrium modulus. Micropipette aspiration resulted in reduced membrane bleb formation in IFT88orpk cells. Following membrane blebbing, IFT88orpk cells exhibited slower reformation of the actin cortex. IFT88orpk cells showed increased actin deformability and reduced cortical tension confirming that IFT regulates actin cortex mechanics. The reduced cortical tension is also consistent with the reduced bleb formation.

Conclusions: this study demonstrates for the first time that the ciliary protein IFT88 regulates fundamental actin organisation and the stiffness of the actin cortex leading to alterations in cell deformation, mechanical properties and blebbing in an IFT88 chondrocyte cell line. This adds to the growing understanding of the role of primary cilia and IFT in regulating cartilage biology.

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Accepted/In Press date: 12 October 2015
e-pub ahead of print date: 19 October 2015
Published date: 16 February 2016

Identifiers

Local EPrints ID: 488397
URI: http://eprints.soton.ac.uk/id/eprint/488397
ISSN: 1063-4584
PURE UUID: 19601449-35e3-4d9b-b2b3-e0f0026c8081
ORCID for A.K.T. Wann: ORCID iD orcid.org/0000-0002-8224-8661

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Date deposited: 21 Mar 2024 17:41
Last modified: 21 Jun 2024 02:06

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Contributors

Author: Z. Wang
Author: A.K.T. Wann ORCID iD
Author: C.L. Thompson
Author: A. Hassen
Author: W. Wang
Author: M.M. Knight

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