Interphase Chromosomes in Replicative Senescence: Chromosome Positioning as a Senescence Biomarker and the Lack of Nuclear Motor-Driven Chromosome Repositioning in Senescent Cells.

Ishita S Mehta,Kumars Riyahi,Karen J Meaburn,Rita Torres Pereira,Ian R Kill,Christopher H Eskiw,Martin Figgitt,Joanna M Bridger

doi:10.3389/fcell.2021.640200

Abstract

This study demonstrates, and confirms, that chromosome territory positioning is altered in primary senescent human dermal fibroblasts (HDFs). The chromosome territory positioning pattern is very similar to that found in HDFs made quiescent either by serum starvation or confluence; but not completely. A few chromosomes are found in different locations. One chromosome in particular stands out, chromosome 10, which is located in an intermediate location in young proliferating HDFs, but is found at the nuclear periphery in quiescent cells and in an opposing location of the nuclear interior in senescent HDFs. We have previously demonstrated that individual chromosome territories can be actively and rapidly relocated, with 15 min, after removal of serum from the culture media. These chromosome relocations require nuclear motor activity through the presence of nuclear myosin 1β (NM1β). We now also demonstrate rapid chromosome movement in HDFs after heat-shock at 42°C. Others have shown that heat shock genes are actively relocated using nuclear motor protein activity via actin or NM1β (Khanna et al., 2014; Pradhan et al., 2020). However, this current study reveals, that in senescent HDFs, chromosomes can no longer be relocated to expected nuclear locations upon these two types of stimuli. This coincides with a entirely different organisation and distribution of NM1β within senescent HDFs.

Highlights

Senescence is described as a gradual accumulation of nondividing cells throughout the reproductive life span of culture (Hayflick and Moorhead, 1961; Kill et al, 1994; Ben-Porath and Weinberg, 2004), it is a major obstacle to continuous propagation of cells, and is often regarded as a tumour suppressing mechanism (Kill, 1998; Campisi, 2001, 2003a,b)
We found that in senescent human dermal fibroblasts (HDFs) chromosome 10 territories did not relocate to the nuclear periphery (Figure 6C), where they are found in young quiescent HDF (Figure 6B) but remained within the nuclear interior (Figure 6C)
We have previously demonstrated that nuclear myosin 1β (NM1β) is required for whole chromosome movement when HDF are placed in low serum (Mehta et al, 2010) and have shown its distribution is considerably altered in quiescent (Mehta et al, 2010) and in Hutchinson-Gilford Progeria Syndrome (HGPS) HDFs (Mehta et al, 2011)

Summary

Introduction

Senescence is described as a gradual accumulation of nondividing cells throughout the reproductive life span of culture (Hayflick and Moorhead, 1961; Kill et al, 1994; Ben-Porath and Weinberg, 2004), it is a major obstacle to continuous propagation of cells, and is often regarded as a tumour suppressing mechanism (Kill, 1998; Campisi, 2001, 2003a,b). RS cells display telomere shortening (Harley et al, 1990; Allsopp et al, 1995; Blackburn, 2001; Cawthon et al, 2003; Masutomi et al, 2003; Ben-Porath and Weinberg, 2004; Ogami et al, 2004; Davis and Kipling, 2005; Canela et al, 2007), with accumulation of DNA damage through an inability to repair it (Chen et al, 2020), de-repression of p16INK 4a loci (Zindy et al, 1997; Chkhotua et al, 2003; Krishnamurthy et al, 2004; Ressler et al, 2006) and alterations in Rb/p13 or p53/p21CIP1 pathways, both inducing senescence in different ways (Chen et al, 2020). Senescence can be induced by mitochondrial dysfunction (Wiley et al, 2016), chemotherapy drugs, inhibition of histone methyl transferases or histone deactylases (Petrova et al, 2016)

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Conclusion