Adel AL JORD

Godfroid — 2022-09-07T08:16:40Z

Adel Al Jord, Gaëlle Letort, Soline Chanet, Feng-Ching Tsai, Christophe Antoniewski, Adrien Eichmuller, Christelle Da Silva, Jean-René Huynh, Nir S. Gov, Raphaël Voituriez, Marie-Émilie Terret & Marie-Hélène Verlhac

Abstract

Cells remodel their cytoplasm with force-generating cytoskeletal motors. Their activity generates random forces that stir the cytoplasm, agitating and displacing membrane-bound organelles like the nucleus in somatic and germ cells. These forces are transmitted inside the nucleus, yet their consequences on liquid-like biomolecular condensates residing in the nucleus remain unexplored. Here, we probe experimentally and computationally diverse nuclear condensates, that include nuclear speckles, Cajal bodies, and nucleoli, during cytoplasmic remodeling of female germ cells named oocytes. We discover that growing mammalian oocytes deploy cytoplasmic forces to timely impose multiscale reorganization of nuclear condensates for the success of meiotic divisions. These cytoplasmic forces accelerate nuclear condensate collision-coalescence and molecular kinetics within condensates. Disrupting the forces decelerates nuclear condensate reorganization on both scales, which correlates with compromised condensate-associated mRNA processing and hindered oocyte divisions that drive female fertility. We establish that cytoplasmic forces can reorganize nuclear condensates in an evolutionary conserved fashion in insects. Our work implies that cells evolved a mechanism, based on cytoplasmic force tuning, to functionally regulate a broad range of nuclear condensates across scales. This finding opens new perspectives when studying condensate-associated pathologies like cancer, neurodegeneration and viral infections.

More information

Nat Commun. 2022 Aug 29 ;13(1):5070. doi : 10.1038/s41467-022-32675-5

Ioana GENESCU

Godfroid — 2022-04-15T12:24:18Z

Authors : I Genescu, M Aníbal-Martínez, V Kouskoff, N Chenouard, C Mailhes-Hamon, H Cartonnet, L Lokmane, F M. Rijli, G López-Bendito, F Gambino, S Garel

Summary

Cortical wiring relies on guidepost cells and activity-dependent processes that are thought to act sequentially. Here, we show that the construction of layer 1 (L1), a main site of top-down integration, is regulated by crosstalk between transient Cajal-Retzius cells (CRc) and spontaneous activity of the thalamus, a main driver of bottom-up information. While activity was known to regulate CRc migration and elimination, we found that prenatal spontaneous thalamic activity and NMDA receptors selectively control CRc early density, without affecting their demise. CRc density, in turn, regulates the distribution of upper layer interneurons and excitatory synapses, thereby drastically impairing the apical dendrite activity of output pyramidal neurons. In contrast, postnatal sensory-evoked activity had a limited impact on L1 and selectively perturbed basal dendrites synaptogenesis. Collectively, our study highlights a remarkable interplay between thalamic activity and CRc in L1 functional wiring, with major implications for our understanding of cortical development.

More information

Cell Reports Vol. 39, Issue 2, 110667, April 12, 2022. doi : 10.1016/j.celrep.2022.110667

ENS - MemoLife

Adel AL JORD

Abstract

Ioana GENESCU

Summary