Biology subjects

Klingberg, T.

Publications and source records attributed to Klingberg, T..

3 recordsLinked to original sources

bioRxiv2023

Transcriptional clusters follow a conserved condensation-dispersal sequence during stem cell differentiation

Spatiotemporal organization of transcription is essential for organism development. Most eukaryotic genes are transcribed by RNA polymerase II (Pol II). In stem cells, Pol II forms prominent clusters, which gradually disappear during differentiation, such that only smaller clusters remain. Here, we ask whether the formation and loss of large Pol II clusters is a stereotypical process explicable by changes in the Pol II transcriptional state during differentiation. We assess clusters by super-resolution microscopy in differentiating mouse embryonic stem cells, sperm precursor formation in fruit flies, and germ layer induction in zebrafish. In all cases, Pol II clusters first become larger and rounder, then unfold, and finally disperse into small clusters. These shape changes are accompanied by initial increase in recruited Pol II, subsequent transition into transcript elongation, and finally reduction of active enhancers. We reproduce these observations using a biophysical surface condensation model, where enhancers support Pol II cluster formation, and transcriptional activity unfolds clusters. Our work indicates that changes in enhancer marks and transcriptional activity during differentiation define a stereotyped trajectory through a generally applicable space of cluster shapes. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=189 HEIGHT=200 SRC="FIGDIR/small/547621v1_ufig1.gif" ALT="Figure 1"> View larger version (35K): org.highwire.dtl.DTLVardef@1fb769borg.highwire.dtl.DTLVardef@27f6a0org.highwire.dtl.DTLVardef@1b0ab7corg.highwire.dtl.DTLVardef@1ca932d_HPS_FORMAT_FIGEXP M_FIG C_FIG

developmental biology↗

bioRxiv2021

RNA polymerase II clusters form in line with liquid phase wetting of chromatin

It is essential for cells to control which genes are transcribed into RNA. In eukaryotes, two major control points are recruitment of RNA polymerase II (Pol II) into a paused state and subsequent pause release to begin transcript elongation. Pol II associates with macromolecular clusters during recruitment, but it remains unclear how Pol II recruitment and pause release might affect these clusters. Here, we show that clusters exhibit morphologies that are in line with wetting of chromatin by a liquid phase enriched in recruited Pol II. Applying instantaneous structured illumination microscopy and stimulated emission double depletion microscopy to pluripotent zebrafish embryos, we find recruited Pol II associated with large clusters, and elongating Pol II with dispersed clusters. A lattice kinetic Monte Carlo model representing recruited Pol II as a liquid phase reproduced the observed cluster morphologies. In this model, chromatin is a copolymer chain containing regions that attract or repel recruited Pol II, supporting droplet formation by wetting or droplet dispersal, respectively.

biophysics↗

bioRxiv2019

Independent effects of socioeconomic status and genetics on adolescent cognition and brain development.

Genetic factors and socioeconomic (SES) inequalities play a large role in educational attainment, and both have been associated with variations in brain structure and cognition. However, genetics and SES are correlated, and no prior study has assessed their neural associations independently. Here we used polygenic score for educational attainment (EduYears-PGS) as well as SES, in a longitudinal study of 551 adolescents, to tease apart genetic and environmental associations with brain development and cognition. Subjects received a structural MRI scan at ages 14 and 19. At both time-points, they performed three working memory (WM) tasks. SES and EduYears-PGS were correlated (r = 0.27) and had both common and independent associations with brain structure and cognition. Specifically, lower SES was related to less total cortical surface area and lower WM. EduYears-PGS was also related to total cortical surface area, but in addition had a regional association with surface area in the right parietal lobe, a region related to non-verbal cognitive functions, including mathematics, spatial cognition, and WM. SES, but not EduYears-PGS, was related to a change in total cortical surface area from age 14 to 19. This is the first study demonstrating a regional association of EduYears-PGS and the independent prediction of SES on cognitive function and brain development. It suggests that the SES inequalities, in particular parental education, are related to global aspects of cortical development, and exert a persistent influence on brain development during adolescence. Significance statementThe influence of socioeconomic (SES) inequalities on brain and cognitive development is a hotly debated topic. However, previous studies have not considered that genetic factors overlap with SES. Here we showed, for the first time, that SES and EduYears-PGS (a score from thousands of genetic markers for educational attainment) have independent associations with both cognition and global cortical surface area in adolescents. EduYears-PGS also had a localized association in the brain: the intraparietal sulcus, a region related to non-verbal intelligence. In contrast, SES had global, but not regional, associations, and these persisted throughout adolescence. This suggests that the influence of SES inequalities is widespread - a result that opposes the current paradigm and can help inform policies in education.

neuroscience↗