DOT1L promotes progenitor proliferation and primes neuronal layer identity in the developing cerebral cortex

Abstract

Cortical development is controlled by transcriptional programs, which are orchestrated by transcription factors. Yet, stable inheritance of spatio-temporal activity of factors influencing cell fate and localization in different layers is only partly understood. Here we find that deletion of Dot1l in the murine telencephalon leads to cortical layering defects, indicating DOT1L activity and chromatin methylation at H3K79 impact on the cell cycle, and influence transcriptional programs conferring upper layer identity in early progenitors. Specifically, DOT1L prevents premature differentiation by increasing expression of genes that regulate asymmetric cell division (Vangl2, Cenpj). Loss of DOT1L results in reduced numbers of progenitors expressing genes including SoxB1 gene family members. Loss of DOT1L also leads to altered cortical distribution of deep layer neurons that express either TBR1, CTIP2 or SOX5, and less activation of transcriptional programs that are characteristic for upper layer neurons (Satb2, Pou3f3, Cux2, SoxC family members). Data from three different mouse models suggest that DOT1L balances transcriptional programs necessary for proper neuronal composition and distribution in the six cortical layers. Furthermore, because loss of DOT1L in the pre-neurogenic phase of development impairs specifically generation of SATB2-expressing upper layer neurons, our data suggest that DOT1L primes upper layer identity in cortical progenitors.

Poor concordance of floxed sequence recombination in single neural stem cells: Implications for cell autonomous studies

“…Our findings do not necessarily undermine previous studies, which have identified cell autonomous gene functions using stop-floxed reporters as a marker of target gene recombined cells (Franz et al, 2019;Zhang et al 2019;Zhou et al, 2018;Zimmermann et al, 2018). If target gene recombination has a large cell-autonomous effect, it may still be detectable in reporter-expressing cells due to the subpopulation of cells in which fluorescent protein presence is a true signal.…”

“…In many studies, NSPC-targeted CreER T2 -lox systems are combined with a ubiquitously-expressed stop-floxed fluorescent reporter gene to confirm recombination in NSPCs (Kirby et al, 2015;Tannenholz et al, 2016) (Sun et al, 2014). It is also common to use these fluorescent proteins more cellspecifically to investigate cell autonomous effects of recombination in the experimental gene of interest (Franz et al, 2019;Zhang et al 2019;Zhou et al, 2018;Zimmermann et al, 2018). These cell autonomous experimental paradigms suppose that target gene and fluorescence reporter gene recombination occur in the same cell with high probability, allowing investigators to identify cell autonomous effects by comparing fluorescent and non-fluorescent cells.…”

The Role of Dot1l in Prenatal and Postnatal Murine Chondrocytes and Trabecular Bone

“…However, regulation of cell cycle and differentiation by Dot1l has been reported in other cell types, including hematopoietic cells (20) and cortical neurons. (35) Dot1l loss in postnatal mouse chondrocytes also led to weakened trabecular bone. In particular, there was decrease in total trabecular bone (BV/TV) as well as changes in bone morphology (BS/BV), both of which are correlated with callus strength of healing fracture.…”

“…No previous studies have specifically examined cell cycle in Dot1l‐ deleted growth plates. However, regulation of cell cycle and differentiation by Dot1l has been reported in other cell types, including hematopoietic cells and cortical neurons …”

Dot1L methyltransferase activity is a barrier to acquisition of pluripotency but not transdifferentiation

“…In both models, Dot1L KO results in disorganized yolk sacs containing primitive erythrocytes. Dot1L is also necessary for development of the heart (Nguyen and Zhang, 2011), cerebral cortex (Franz et al, 2019), and chondrocytes (Castaño Betancourt et al, 2012).…”