Engagement of vimentin intermediate filaments in hypotonic stress

Abstract

Intermediate filaments (IFs) play a key role in the control of cell structure and morphology, cell mechano-responses, migration, proliferation, and apoptosis.However, the mechanisms regulating IFs organization in motile adhesive cells under certain physical/pathological conditions remain to be fully understood.In this study, we found hypo-osmotic-induced stress results in a dramatic but reversible rearrangement of the IF network. Vimentin and nestin IFs are partially depolymerized as they are redistributed throughout the cell cytoplasm after hypo-osmotic shock. This spreading of the IFs requires an intact microtubule network and the motor protein associated transportation. Both nocodazole treatment and depletion of kinesin-1 (KIF5B) block the hypoosmotic shock-induced rearrangement of IFs showing that the dynamic behavior of IFs largely depends on microtubules and kinesin-dependent transport. Moreover, we show that cell survival rates are dramatically decreased in response to hypo-osmotic shock, which was more severe by vimentin IFs depletion, indicating its contribution to osmotic endurance. Collectively, these results reveal a critical role of vimentin IFs under hypotonic stress and provide evidence that IFs are important for the defense mechanisms during the osmotic challenge. K E Y W O R D S cytoplasmic redistribution, hypo-osmosis, intermediate filaments, osmotic stress, vimentin

Hypotonic Stress Induces Fast, Reversible Degradation of the Vimentin Cytoskeleton via Intracellular Calcium Release

“…Consequently, the observed fast degradation of vimentin filaments, but not actin filaments or microtubules, under hypotonic stress cannot be explained through the intrinsic stabilities of the different filaments. A recent study proposes that microtubule‐based transport may mediate the reorganization of the vimentin cytoskeleton under hypotonic stress . We found that in our case, the fast degradation of the vimentin cytoskeleton persisted upon removal of the microtubule cytoskeletal system (Figure S5, Supporting Information).…”

“…A recent study proposes that microtubule-based transport may mediate the reorganization of the vimentin cytoskeleton under hypotonic stress. [33] We found that in our case, the fast degradation of the vimentin cytoskeleton persisted upon removal of the microtubule cytoskeletal system ( Figure S5, Supporting Information).…”

Mechanical and Non‐Mechanical Functions of Filamentous and Non‐Filamentous Vimentin

“…[ 33 ] Ubiquitination by gigaxonin, an E3‐ligase targeting factor encoded by the giant axonal neuropathy (GAN) gene also leads to vimentin degradation, and mutations in GAN are associated with the accumulation of VIFs in GAN as well as other types of intermediate filaments in the nervous system. [ 34 ] VIFs are also subject to proteolysis by calpain during osmotic shock [ 35,36 ] and are substrates for some bacterial proteases. [ 37 ] VIFs are also cleaved by calpain during pyroptosis of inflammatory cells.…”

Unidirectional Regulation of Vimentin Intermediate Filaments to Caveolin-1

“…According to the previous work, vimentin presented a more spread and diffuse distribution under hypo-osmotic stress [ 17 ]. This perhaps explains why, in the presence of vimentin, the motion of Cav-1 vesicles induced by hypo-osmosis is further hindered.…”

“…Actin-GFP can also be used as a cellular mechanical framework to better characterize the location of Cav-1 vesicles. It is note that, hypo-osmotic stress shows subtle effect to the distribution of actin at least within the initial 5 min [ 17 ]. We also only expressed Cav-1-mCherry without vimentin-GFP or actin-GFP to exclude the effects of overexpressing cytoskeletal proteins to the vesicle motility, the results remained the same (data not shown).…”