The rich inner life of the cell nucleus: dynamic organization, active flows, and emergent rheology

Abstract

The cell nucleus stores the genetic material essential for life, and provides the environment for transcription, maintenance, and replication of the genome. Moreover, the nucleoplasm is filled with subnuclear bodies such as nucleoli that are responsible for other vital functions. Overall, the nucleus presents a highly heterogeneous and dynamic environment with diverse functionality. Here, we propose that its biophysical complexity can be organized around three inter-related and interactive facets: heterogeneity, activity, and rheology. Most nuclear constituents are sites of active, ATP-dependent processes and are thus inherently dynamic: The genome undergoes constant rearrangement, the nuclear envelope flickers and fluctuates, nucleoli migrate and coalesce, and many of these events are mediated by nucleoplasmic flows and interactions. And yet there is spatiotemporal organization in terms of hierarchical structure of the genome, its coherently moving regions and membrane-less compartmentalization via phase-separated nucleoplasmic constituents. Moreover, the non-equilibrium or activity-driven nature of the nucleus gives rise to emergent rheology and material properties that impact all cellular processes via the central dogma of molecular biology. New biophysical insights into the cell nucleus can come from appreciating this rich inner life.

Biophysical Reviews—the IUPAB journal tasked with advancing biophysics

“…The requirement for nomination is that the young scientist be currently involved in biophysical research and be under 40 by the deadline of application. In 2020, the inaugural ‘Michèle Auger Award for Young Scientists’ Independent Research’ was conducted and this competition was won by Dr. Alexandra Zidovska, Assistant Professor at New York University (Hall 2020b ; Zidovska 2020 ). For the 2021 award, the journal received 15 nominations.…”

Biophysical Reviews—A call to young biophysicists

“…For those interested in entering (or nominating another) additional details about the judging and selection of winners for the previous years' competitions can be found in the following references: Hall (2020bHall ( , 2020cHall ( , 2020d; Hall (2021bHall ( , 2021c. The 2020 winner's published review article can be found here (Zidovska 2020) with the 2021 winner's published review article set to appear in the upcoming Issue 4.…”

“…The winner's published Review will carry a short foreword about the life of Professor Michèle Auger, along with her work associated with teaching and training the next generation of biophysical scientists. First run in 2020, the two previous winners were Assistant Professor AlexandraZidovska (2020) and Associate Professor Jorge Alegre-Cebollada (2021). Their public research details can be found below.…”

Biophysical Reviews: 2020—looking back, going forward

“…A feature of this Issue was the invited review article by Dr. Alexandra Zidovska, the inaugural winner of the Michèle Auger award for young scientists’ independent research (Hall 2019a , b ; IUPAB 2018 ). In her award article Alexandra reviewed salient material within her thematic topic of cytosol rheology (Zidovska 2020 ). In addition, her article carried two short personal biographies of both herself and Michele Auger—the scientist and former Biophysical Reviews Editorial Board Member for whom the award acts as a perpetual memorial.…”