S-Phase phosphorylation of lamin B2

AbstractLamin B2 modification in synchronously dividing populations of human diploid fibroblasts was determined by 2-dimensional gel electrophoresis and [32P]orthophosphate labelling. In quiescent (G0) and G1 cultures of HDF, lamin B2 migrated as 2 spots on 2-dimensional gels. In contrast, in S-phase populations of HDF lamin B2 migrated as a single basic species. The level of lamin B2 phosphorylation was determined after immunoisolation from [32P]orthophosphate labelled cells. The results of these experiments indicated a 2–3-fold increase in the steady state level of lamin B2 phosphorylation in S-phase HDF compared with G0 HDF. Consistent with this evidence, tryptic peptide maps revealed the presence of a phosphopeptide in S-phase lamin B2 which was absent from G0 lamin B2. Since all of the phosphate incorporated into S-phase and G0 lamin B2 was recovered in serine residues we conclude that the S-phase specific phosphopeptide did not represent either of the cdc2 sites associated with entry nuclear lamina breakdown

The Future of Dancefloors: Building More Flexible, Open and Innovative Clubbing Experiences

Nightclubs across the world are in a state of crisis due to COVID-19, and neither inaction or ‘business as usual’ are viable options if the industry is to survive it. It has never been more important to question, innovate and re-imagine the status quo

Alterations to nuclear architecture and genome behavior in senescent cells.

The organization of the genome within interphase nuclei, and how it interacts with nuclear structures is important for the regulation of nuclear functions. Many of the studies researching the importance of genome organization and nuclear structure are performed in young, proliferating, and often transformed cells. These studies do not reveal anything about the nucleus or genome in nonproliferating cells, which may be relevant for the regulation of both proliferation and replicative senescence. Here, we provide an overview of what is known about the genome and nuclear structure in senescent cells. We review the evidence that nuclear structures, such as the nuclear lamina, nucleoli, the nuclear matrix, nuclear bodies (such as promyelocytic leukemia bodies), and nuclear morphology all become altered within growth-arrested or senescent cells. Specific alterations to the genome in senescent cells, as compared to young proliferating cells, are described, including aneuploidy, chromatin modifications, chromosome positioning, relocation of heterochromatin, and changes to telomeres

Primary laminopathy fibroblasts display altered genome organization and apoptosis

A number of diseases associated with specific tissue degeneration and premature aging have mutations in the nuclear envelope proteins A-type lamins or emerin. Those diseases with A-type lamin mutation are inclusively termed laminopathies. Due to various hypothetical roles of nuclear envelope proteins in genome function we investigated whether alterations to normal genomic behaviour are apparent in cells with mutations in A-type lamins and emerin. Even though the distributions of these proteins in proliferating laminopathy fibroblasts appear normal, there is abnormal nuclear positioning of both chromosome 18 and 13 territories, from the nuclear periphery to the interior. This genomic organization mimics that found in normal nonproliferating quiescent or senescent cells. This finding is supported by distributions of modified pRb in the laminopathy cells. All laminopathy cell lines tested and an X-linked Emery-Dreifuss muscular dystrophy cell line also demonstrate increased incidences of apoptosis. The most extreme cases of apoptosis occur in cells derived from diseases with mutations in the tail region of the LMNA gene, such as Dunningan-type familial partial lipodystrophy and mandibuloacral dysplasia, and this correlates with a significant level of micronucleation in these cells

Digestible energy levels for gilts in a high temperature environment

Fifty crossbred female piglets, from 30 to 60 kg, were used to evaluate the effects of five dietary digestible energy (DE) levels on performance and carcass composition at a high environmental temperature (32.04 ± 0.88°C). The experimental design was randomized blocks with five treatments (3 100, 3 250, 3 400, 3 550, and 3 700 kcal DE/kg), five replicates and two animals per experimental unit. DE level did not influence daily weight gain, (treatment means from 641 to 687 g) or intakes of feed, energy and protein. Feed conversion improved linearly (P<.05) with increasing dietary DE level. The diet with 3 700 kcal ED/kg, in which soybean oil supplied 20.8% of the total energy, gave the best feed conversion (2.34 g/g). Protein deposition rate decreased (P<.05), while fat deposition rate increased (P<.01) linearly with increasing DE concentration

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

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