bioRxiv Science⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/2022.01.19.476939

Lysosomes are Required for Early Dorsal Signaling in the Xenopus Embryo

Tejeda Munoz, N.·De Robertis, E. M.
View original source ↗Export metadata ↓

Abstract

Lysosomes are the digestive center of the cell and play important roles in human disease, including cancer. Previous work has suggested that late endosomes, also known as multivesicular bodies (MVBs), and lysosomes are essential for canonical Wnt pathway signaling. Sequestration of Glycogen Synthase 3 (GSK3) and of {beta}{square}catenin destruction complex components in MVBs is required for sustained canonical Wnt signaling. Little is known about the role of lysosomes during early development. In the Xenopus egg, a Wnt-like cytoplasmic determinant signal initiates formation of the body axis following a cortical rotation triggered by sperm entry. Here we report that cathepsin D was activated in lysosomes specifically on the dorsal marginal zone of the embryo at 64-cell stage, long before zygotic transcription starts. Expansion of the multivesicular body (MVB) compartment with low-dose Hydroxychloroquine (HCQ) greatly potentiated the dorsalizing effects of the Wnt agonist Lithium chloride (LiCl) in embryos, and this effect required macropinocytosis. Formation of the dorsal axis required lysosomes, as indicated by brief treatments with the vacuolar ATPase (V-ATPase) Bafilomycin A1 inhibitor at the 32-cell stage. Inhibiting the MVB-forming machinery with a dominant-negative point mutation in Vacuolar Protein Sorting 4 (Vps4-EQ) also interfered with the endogenous dorsal axis. The Wnt-like activity of the dorsal cytoplasmic determinant Huluwa (Hwa), and that of microinjected xWnt8 mRNA, also required lysosome acidification and the MVB-forming machinery. We conclude that lysosome function is essential for early dorsal axis development in Xenopus. The results highlight the intertwining between membrane trafficking, lysosomes, and vertebrate axis formation. SignificanceThe dorsal axis of the vertebrate Xenopus embryo is established by an early Wnt signal generated by a rotation of the cortex of the egg towards the opposite side of the sperm entry point. In this study, we report that lysosomal Cathepsin D becomes activated on the dorsal marginal zone of the embryo already at the 64-cell stage, and that this asymmetry is enhanced by increasing Wnt signaling levels. We present experiments showing that lysosome activity, macropinocytosis, and multivesicular body formation are required for the dorsal signal provided maternally in the egg, and for twinning by microinjected huluwa and Wnt8 mRNA. The results indicate that the cell biology of lysosomes plays a fundamental role in vertebrate development.

Source connections

Explore related subjects

developmental biologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Tejeda Munoz, N., De Robertis, E. M.. 2022-01-20. Lysosomes are Required for Early Dorsal Signaling in the Xenopus Embryo. https://doi.org/10.1101/2022.01.19.476939

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

KEEP EXPLORING

Related preprints

bioRxiv2026

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↗
bioRxiv2026

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↗
bioRxiv2026

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↗