bims-micesi 2023-01-01 papers

bims-micesi

Biomed News

on Mitotic cell signalling

Issue of 2023–01–01
six papers selected by
Valentina Piano, Uniklinik Köln

Contribution of integrin adhesion to cytokinetic abscission and genomic integrity.
FAIRE-MS reveals mitotic retention of transcriptional regulators on a proteome-wide scale.
Bayesian inference of multi-point macromolecular architecture mixtures at nanometre resolution.
Nuclear-cytoplasmic compartmentalization of cyclin B1-Cdk1 promotes robust timing of mitotic events.
Regulation of cell size and Wee1 kinase by elevated levels of the cell cycle regulatory protein kinase Cdr2.
Piezo mechanosensory channels regulate centrosome integrity and mitotic entry.

Front Cell Dev Biol. 2022 ;10 1048717

Contribution of integrin adhesion to cytokinetic abscission and genomic integrity.

Bhavna Rani, Deepesh K Gupta, Staffan Johansson, Siamak A Kamranvar.

  Recent research shows that integrin-mediated adhesion contributes to the regulation of cell division at two key steps: the formation of the mitotic spindle at the mitotic entry and the final cytokinetic abscission at the mitotic exit. Failure in either of these processes will have a direct impact on the other in each round of the cell cycle and on the genomic integrity. This review aims to present how integrin signals are involved at these cell cycle stages under normal conditions and some safety mechanisms that may counteract the generation of aneuploid cells in cases of defective integrin signals.

Keywords:  abscission; centrosome; genome integrity; integrin; mitosis

DOI:  https://doi.org/10.3389/fcell.2022.1048717
FASEB J. 2023 Feb;37(2): e22724

FAIRE-MS reveals mitotic retention of transcriptional regulators on a proteome-wide scale.

Bingyu Ye, Wenlong Shen, Yanchang Li, Dong Wang, Yan Zhang, Ping Li, Man Yin, Yahao Wang, Dejian Xie, Shu Shi, Tao Yao, Juncai Chen, Ping Xu, Zhihu Zhao.

  Mitosis entails global and dramatic alterations, such as higher-order chromatin organization disruption, concomitant with global transcription downregulation. Cells reliably re-establishing gene expression patterns upon mitotic exit and maintaining cellular identities remain poorly understood. Previous studies indicated that certain transcription factors (TFs) remain associated with individual loci during mitosis and serve as mitotic bookmarkers. However, it is unclear which regulatory factors remain bound to the compacted mitotic chromosomes. We developed formaldehyde-assisted isolation of regulatory elements-coupled mass spectrometry (FAIRE-MS) that combines FAIRE-based open chromatin-associated protein pull-down and mass spectrometry (MS) to quantify the open chromatin-associated proteome during the interphase and mitosis. We identified 189 interphase and mitosis maintained (IM) regulatory factors using FAIRE-MS and found intrinsically disordered proteins and regions (IDP(R)s) are highly enriched, which plays a crucial role in liquid-liquid phase separation (LLPS) and chromatin organization during the cell cycle. Notably, in these IDP(R)s, we identified mitotic bookmarkers, such as CEBPB, HMGB1, and TFAP2A, and several factors, including MAX, HMGB3, hnRNP A2/B1, FUS, hnRNP D, and TIAL1, which are at least partially bound to the mitotic chromosome. Furthermore, it will be essential to study whether these IDP(R)s through LLPS helps cells transit from mitosis to the G1 phase during the cell cycle.

Keywords:  cell identity; intrinsically disordered proteins; mitotic bookmarking; transcription factor

DOI:  https://doi.org/10.1096/fj.202201038RRR
PLoS Comput Biol. 2022 Dec 27. 18(12): e1010765

Bayesian inference of multi-point macromolecular architecture mixtures at nanometre resolution.

Peter A Embacher, Tsvetelina E Germanova, Emanuele Roscioli, Andrew D McAinsh, Nigel J Burroughs.

Gaussian spot fitting methods have significantly extended the spatial range where fluorescent microscopy can be used, with recent techniques approaching nanometre (nm) resolutions. However, small inter-fluorophore distances are systematically over-estimated for typical molecular scales. This bias can be corrected computationally, but current algorithms are limited to correcting distances between pairs of fluorophores. Here we present a flexible Bayesian computational approach that infers the distances and angles between multiple fluorophores and has several advantages over these previous methods. Specifically it improves confidence intervals for small lengths, estimates measurement errors of each fluorophore individually and infers the correlations between polygon lengths. The latter is essential for determining the full multi-fluorophore 3D architecture. We further developed the algorithm to infer the mixture composition of a heterogeneous population of multiple polygon states. We use our algorithm to analyse the 3D architecture of the human kinetochore, a macro-molecular complex that is essential for high fidelity chromosome segregation during cell division. Using triple fluorophore image data we unravel the mixture of kinetochore states during human mitosis, inferring the conformation of microtubule attached and unattached kinetochores and their proportions across mitosis. We demonstrate that the attachment conformation correlates with intersister tension and sister alignment to the metaphase plate.

DOI: https://doi.org/10.1371/journal.pcbi.1010765
Cell Rep. 2022 Dec 27. pii: S2211-1247(22)01766-1. [Epub ahead of print]41(13): 111870

Nuclear-cytoplasmic compartmentalization of cyclin B1-Cdk1 promotes robust timing of mitotic events.

Gembu Maryu, Qiong Yang.

  The cyclin-dependent kinase (Cdk1) oscillator is widely characterized in homogenized cytosolic extracts, leaving unclear the impact of nucleocytoplasmic compartmentalization. Here, by developing a Förster resonance energy transfer (FRET) biosensor, we track Cdk1 spatiotemporal dynamics in reconstituted cells with or without side by side and find compartmentalization significantly modulates clock properties previously found in bulk studies. Although nucleus-absent cells display highly tunable frequency, the nucleus-present cells maintain constant frequency against cyclin B1 variations. Despite high expression variability, cyclin degraded within the same duration, enabling a robust mitotic phase. Moreover, Cdk1 and cyclin B1 cycle rigorously out-of-phase, ensuring wide phase-plane orbits, essential for oscillation robustness. Although Cdk1 in homogeneous extracts is well known for delayed switch-like activation, we find active cyclin B1-Cdk1 accumulates in nuclei, without delay, until the nuclear envelope breakdown (NEB) when another abrupt activation triggers anaphase. Cdk1 biphasic activation and spatial compartmentalization may together coordinate the accurate ordering of different downstream events.

Keywords:  CP: Cell biology; FRET imaging; cell cycle robustness; cell-free extracts; cyclin-dependent kinase (Cdk); droplet microfluidics; frequency tunability; limit-cycle oscillations; nuclear-cytoplasmic compartmentalization; phase-plane trajectory; synthetic cells

DOI:  https://doi.org/10.1016/j.celrep.2022.111870
J Biol Chem. 2022 Dec 24. pii: S0021-9258(22)01274-1. [Epub ahead of print] 102831

Regulation of cell size and Wee1 kinase by elevated levels of the cell cycle regulatory protein kinase Cdr2.

Rachel A Berg, James B Moseley.

  Many cell cycle regulatory proteins catalyze cell cycle progression in a concentration-dependent manner. In the fission yeast S. pombe, the protein kinase Cdr2 promotes mitotic entry by organizing cortical oligomeric nodes that lead to inhibition of Wee1, which itself inhibits the cyclin-dependent kinase Cdk1. cdr2Δ cells lack nodes and divide at increased size due to overactive Wee1, but it has not been known how increased Cdr2 levels might impact Wee1 and cell size. It also has not been clear if and how Cdr2 might regulate Wee1 in the absence of the related kinase Cdr1/Nim1. Using a Tetracycline-inducible expression system, we found that a 6X increase in Cdr2 expression caused hyperphosphorylation of Wee1 and reduction in cell size even in the absence of Cdr1/Nim1. This overexpressed Cdr2 formed clusters that sequestered Wee1 adjacent to the nuclear envelope. Cdr2 mutants that disrupt either kinase activity or clustering ability failed to sequester Wee1 and to reduce cell size. We propose that Cdr2 acts as a dosage-dependent regulator of cell size by sequestering its substrate Wee1 in cytoplasmic clusters, away from Cdk1 in the nucleus. This mechanism has implications for other clustered kinases, which may act similarly by sequestering substrates.

Keywords:  Cdr2; Wee1; cell size; mitosis; pombe; tetracycline; yeast

DOI:  https://doi.org/10.1016/j.jbc.2022.102831
Proc Natl Acad Sci U S A. 2023 Jan 03. 120(1): e2213846120

Piezo mechanosensory channels regulate centrosome integrity and mitotic entry.

Liron David, Laurel Martinez, Qiongchao Xi, Kameron A Kooshesh, Ying Zhang, Jagesh V Shah, Richard L Maas, Hao Wu.

  Piezo1 and 2 are evolutionarily conserved mechanosensory cation channels known to function on the cell surface by responding to external pressure and transducing a mechanically activated Ca2+ current. Here we show that both Piezo1 and 2 also exhibit concentrated intracellular localization at centrosomes. Both Piezo1 and 2 loss-of-function and Piezo1 activation by the small molecule Yoda1 result in supernumerary centrosomes, premature centriole disengagement, multi-polar spindles, and mitotic delay. By using a GFP, Calmodulin and M13 Protein fusion (GCaMP) Ca2+-sensitive reporter, we show that perturbations in Piezo modulate Ca2+ flux at centrosomes. Moreover, the inhibition of Polo-like-kinase 1 eliminates Yoda1-induced centriole disengagement. Because previous studies have implicated force generation by microtubules as essential for maintaining centrosomal integrity, we propose that mechanotransduction by Piezo maintains pericentrosomal Ca2+ within a defined range, possibly through sensing cell intrinsic forces from microtubules.

Keywords:  Ca2+ signaling; centrioles; centrosomes; mechanotransduction; piezo

DOI:  https://doi.org/10.1073/pnas.2213846120