Microtubules and Vimentin Fiber Stability during Parabolic Flights

Simon L Wuest,Geraldine Cerretti,Christian Jost,Martina Caliò,Sarah Gander,Fabian Ille,Othmar Schälli,Christoph Zumbühl,Jaro Arnold,Gerhard S Székely,Cindy Follonier,Marcel Egli,Christina Giger-Lange,Karin Rattenbacher-Kiser

doi:10.1007/s12217-020-09818-8

Simon L Wuest, Geraldine Cerretti + Show 12 more

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https://doi.org/10.1007/s12217-020-09818-8

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Abstract

Adequate mechanical stimulation is essential for cellular health and tissue maintenance, including articular cartilage, which lines the articulating bones in joints. Chondrocytes, which are the sole cells found in articular cartilage, are responsible for matrix synthesis, maintenance and degradation. It is generally believed that chondrocytes require mechanical stimuli through daily physical activity for adequate cartilage homeostasis. However, to date, the molecular mechanisms of cellular force sensing (mechanotransduction) are not fully understood. Among other mechanisms, the cytoskeleton is thought to play a key role. Despite that gravity is a very small force at the cellular level, cytoskeletal adaptations have been observed under altered gravity conditions of a parabolic flight in multiple cell types. In this study, we developed a novel hardware which allowed to chemically fix primary bovine chondrocytes at 7 time points over the course of a 31-parabola flight. The samples were subsequently stained for the microtubules and vimentin network and microscopic images were acquired. The images showed a large heterogeneity among the cells in morphology as well as in the structure of both networks. In all, no changes or adaptions in cytoskeleton structure could be detected over the course of the parabolic flight.

Highlights

Adequate mechanical stimulation is essential for cellular health and tissue maintenance, such as in articularThis article belongs to the Topical Collection on The Effect of Gravity on Physical and Biological Phenomena Guest Editor: Valentina Shevtsova Electronic supplementary material The online version of this article contains supplementary material, which is available to authorized users.Chondrocytes are the sole cells found in articular cartilage and are responsible for matrix synthesis, maintenance, and degradation (reviewed in (Buckwalter et al 1994; Haqqi et al 2000; Ulrich-Vinther et al 2003; Akkiraju and Nohe 2015))
Since chondrocytes are exposed to mechanical loading during daily physical activity, it is generally believed that chondrocytes require mechanical stimuli for adequate cartilage homeostasis (reviewed in (Mobasheri et al 2002; Grad et al 2011; Anderson and Johnstone 2017))
Even though gravity is a tiny force at the cellular level, cytoskeletal rearrangements or adaptations have been observed under altered gravity conditions of a parabolic flight in multiple cell types (Rosner et al 2006; Yang et al 2010; Ulbrich et al 2011; Grosse et al 2012; Aleshcheva et al 2015; Corydon et al 2016)

Summary

Introduction

(2020) 32:921–933 mechanisms on how cells incorporate a mechanical force into a cellular response (mechanotransduction) are not fully understood (reviewed in (Wang and Thampatty 2006; Loon 2007; Eyckmans et al 2011; Wang et al 2014; Wang 2017)). Studies on articular chondrocytes showed a disruption of the tubulin network and holes in the vimentin and cytokeratin network after 31 parabolas, but not after one parabola (Aleshcheva et al 2015). This data suggests a time-dependent reaction of the tubulin and vimentin cytoskeleton to parabolic flight conditions

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