Vimentin Association with Nuclear Grooves in Normal MEF 3T3 Cells.

Karolina Feliksiak,Zenon Rajfur,Daria Solarz,Maciej Guzik,Tomasz Witko

doi:10.3390/ijms21207478

Abstract

Vimentin, an intermediate filament protein present in leukocytes, blood vessel endothelial cells, and multiple mesenchymal cells, such as mouse embryonic fibroblasts (MEF 3T3), is crucial for various cellular processes, as well as for maintaining the integrity and durability (stability) of the cell cytoskeleton. Vimentin intermediate filaments (VIFs) adhere tightly to the nucleus and spread to the lamellipodium and tail of the cell, serving as a connector between the nucleus, and the cell’s edges, especially in terms of transferring mechanical signals throughout the cell. How these signals are transmitted exactly remains under investigation. In the presented work, we propose that vimentin is involved in that transition by influencing the shape of the nucleus through the formation of nuclear blebs and grooves, as demonstrated by microscopic observations of healthy MEF (3T3) cells. Grooved, or “coffee beans” nuclei, have, to date, been noticed in several healthy cells; however, these structures are especially frequent in cancer cells—they serve as a significant marker for recognition of multiple cancers. We observed 288 MEF3T3 cells cultured on polyhydroxyoctanoate (PHO), polylactide (PLA), and glass, and we identified grooves, coaligned with vimentin fibers in the nuclei of 47% of cells cultured on PHO, 50% of cells on glass, and 59% of cells growing on PLA. We also observed nuclear blebs and associated their occurrence with the type of substrate used for cell culture. We propose that the higher rate of blebs in the nuclei of cells, cultured on PLA, is related to the microenvironmental features of the substrate, pH in particular.

Highlights

Vimentin is an intermediate filament protein present in a variety of endothelial and mesenchymal cells
Vimentin Bundles Associated with Nuclear Grooves of the Cells In this work, we investigated the morphology of vimentin cytoskeleton in mouse embryonic fibroblIanstthciesllws o(rMk,EwF e3Tin3v)esctuigltautreeddthoenmgolarspshoalnodgytwofovmimaetenrtiinalscyotof shkieglhetopnotiennmtiaolusaeppemlicbartyioonnicin bifoibmreodbilcaisntecaenllds t(isMsuEeFen3Tg3in)eceurilntugr—edpoolnyhgyldasrosxaynodctatwnooatmesanodf phoiglyhlapcotitdeen(tiPaLl Aa)p.pWliecamtiaonnagined toboiobmseerdveictihnieckaenrdbutnisdsulees oefnvgiimneeenrtiningfi—bpeorslyihnyadfrroaxcytioocntaonfotahteece(PllHs cOu)ltuanredd opnoltyhleacgtildases,(aPsLsAh)o.wWnein thme aFnigaugreed1t.o observe thicker bundles of vimentin fibers in a fraction of the cells cultured on the glass, as shown in the Figure 1
We investigated 288 nuclei of MEF 3T3 cells and found that is vimentin filling the spaces created by the nuclear grooves, whose creation was, to date, associated with microtubules, and that it reaches the deeper areas of the invaginations towards the interior of the nucleus

Summary

Introduction

Vimentin is an intermediate filament protein present in a variety of endothelial and mesenchymal cells It is mostly known for protecting the cell as a whole, and its inner organelles separately [1], and for ensuring cell cytoskeleton stability [2,3]. The invaginations in the nuclei are usually referred to the pathological feature of cancer cells and are identified as longitudinal nuclear membrane folds along the long axis of the nucleus. The shape of these nuclei resembles coffee beans, yet the pathogenesis beyond the presence of these structures is not known. It has been shown that neither of the major structural proteins of the nuclear envelope, such as lamin A, B, B1, and C, nor lamin B receptor or emerin, are involved in the formation of the grooves [10]

Methods

Results

Conclusion