Search bioRxiv⌕ Search

bioRxiv · 10.1101/2022.06.27.497841

Craniofacial dysmorphology in Down Syndrome is caused by increased dosage of Dyrk1a and at least three other genes

Abstract

Down syndrome (DS), trisomy of human chromosome 21 (Hsa21), occurs in 1 in 800 live births and is the most common human aneuploidy. DS results in multiple phenotypes, including craniofacial dysmorphology, characterised by midfacial hypoplasia, brachycephaly and micrognathia. The genetic and developmental causes of this are poorly understood. Using morphometric analysis of the Dp1Tyb mouse model of DS and an associated genetic mouse genetic mapping panel, we demonstrate that four Hsa21-orthologous regions of mouse chromosome 16 contain dosage-sensitive genes that cause the DS craniofacial phenotype, and identify one of these causative genes as Dyrk1a. We show that the earliest and most severe defects in Dp1Tyb skulls are in bones of neural crest (NC) origin, and that mineralisation of the Dp1Tyb skull base synchondroses is aberrant. Furthermore, we show that increased dosage of Dyrk1a results in decreased NC cell proliferation and a decrease in size and cellularity of the NC-derived frontal bone primordia. Thus, DS craniofacial dysmorphology is caused by increased dosage of Dyrk1a and at least three other genes. Summary statementCraniofacial dysmorphology in mouse models of Down syndrome is caused by increased dosage of at least four genes including Dyrk1a, resulting in reduced proliferation of neural crest-derived cranial bone progenitors.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Redhead, Y., Gibbins, D., Lana-Elola, E., Watson-Scales, S., Dobson, L., Krause, M., Liu, K., Fisher, E., Green, J., Tybulewicz, V.. 2022-06-28. Craniofacial dysmorphology in Down Syndrome is caused by increased dosage of Dyrk1a and at least three other genes. https://doi.org/10.1101/2022.06.27.497841

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

Dynamic mechanical sorting biases niche occupancy and lineage outcome during development of bilayered glandular epithelia

Tissue compartmentalization into basal and luminal domains is a hallmark of glandular epithelia, yet how fate boundaries are established and stabilized during dynamic morphogenesis remains a major unresolved question. Here, using mouse embryonic explants, organoids, quantitative live imaging and genetic perturbations, we show that basal-luminal compartmentalization is not maintained by fixed boundaries, but through continuous positional corrections. We show that differences in cellular adhesion and actomyosin contractility drive these positional corrections by promoting active cell sorting. We further find that these mechanical differences influence lineage specification by controlling cell positioning rather than directly instructing cell fate. Before commitment, mosaic, but not uniform, perturbation of cell mechanics alters niche occupancy and biases lineage outcome, indicating that relative mechanical properties determine access to fate-instructive niches. Conversely, perturbation of Notch and YAP remodels compartment-specific mechanical properties and cell-positioning dynamics, revealing a reciprocal coupling between lineage state and mechanical sorting. Conservation of this mechanism across four glandular epithelia of distinct origins and functions identifies dynamic mechanical sorting as a general strategy for maintaining robust tissue compartmentalization during the extensive growth and cellular rearrangements of branching morphogenesis.

developmental biology↗

Unbiased lineage tracing across the adipose organ decouples developmental origin from anatomical and transcriptomic identities

The developmental origins of individual adipose depots and whether embryonic lineage dictates adult function remain unresolved. Here, we apply in utero CRISPR-mediated barcoding lineage tracing to construct the first unbiased clonal map of adipose organ development in mice. The developmental hierarchy we uncover challenges several conventions. Remarkably, interscapular brown fat, used as the prototypical brown fat, is the most developmentally isolated brown fat; depots sharing Myf5/Pax3 lineage markers fail to cluster together; mesenteric white fat shares unexpected high clonal ancestry with brown fats despite a radically divergent transcriptome; and subcutaneous white adipose tissues converge transcriptomically despite distant developmental origins. These findings call for a reinterpretation of single-marker lineage tracing data across the adipose organ and propose that adipose depot identity is not solely encoded by embryonic lineage but is substantially shaped by the anatomical niche.

developmental biology↗

Age-dependent mechanical stress underlies unexpected vestibular differentiation and regeneration patterns

Loss of inner-ear sensory hair cells (HCs) is a major cause of hearing and balance disorders. Promoting HC regeneration offers a potential therapeutic strategy, but regenerative capacity is limited in adult mammals and declines rapidly during early postnatal development in mice. HCs can regenerate through trans-differentiation of neighboring supporting cells in a process controlled by Notch mediated lateral inhibition. However, the factors underlying the decrease in regeneration capacity are poorly understood. Here, we combine live imaging with single-HC ablation in mouse vestibular explants to track the dynamics of HC development and regeneration. We reveal unexpected age-dependent deviations from the classical lateral inhibition model, in which new HCs differentiate adjacent to existing HCs. We find that mechanical stress changes with age and that perturbing it alters the observed differentiation patterns. A mathematical model incorporating local mechanical regulation of Notch signaling captures both HC differentiation and regeneration patterns across ages. Together, these findings identify mechanical stress as a crucial regulator of HC differentiation and support an underlying mechanism in which the interplay between local mechanics and Notch signaling shapes regenerative responses. This coupling offers a framework for understanding the age-dependent decline in HC regeneration and motivates investigation of mechanical regulation as a potential therapeutic target.

developmental biology↗