Biology subjects

Diaz-Cuadros, M.

Publications and source records attributed to Diaz-Cuadros, M..

6 recordsLinked to original sources

bioRxiv2026

A genetically encoded redox bottleneck constrains human developmental rate

The intrinsically slow pace of human development poses challenges for regenerative medicine and disease modeling. This trait is attributed to low metabolic rates, yet the endogenous mechanisms determining species-specific metabolic flux remain unknown. Here, we identify coupling between glycolytic NADH production and mitochondrial oxidation through the glycerol-3-phosphate (G3P) shuttle as a genetic bottleneck constraining human developmental tempo. Using stem cell-derived models of the segmentation clock, an oscillator whose period reflects developmental rate, we show that low expression of the G3P shuttle enzyme GPD1L limits NADH oxidation in human progenitors compared to mouse. Overexpressing GPD1L boosts metabolic flux, accelerating the segmentation clock, cell cycle, and differentiation across germ layers. G3P-mediated redox coupling is thus a genetically encoded, rate-limiting mechanism that sets the tempo of human development.

developmental biology↗

bioRxiv2022

Reconstruction and deconstruction of human somitogenesis in vitro

The body of vertebrates displays a segmental organization which is most conspicuous in the periodic organization of the vertebral column and peripheral nerves. This metameric organization is first implemented when somites, which contain the precursors of skeletal muscles and vertebrae, are rhythmically generated from the presomitic mesoderm (PSM). Somites then become subdivided into anterior and posterior compartments essential for vertebral formation and segmental patterning of the peripheral nervous system1-4. How this key somitic subdivision is established remains poorly understood. Here we introduce novel tridimensional culture systems of human pluripotent stem cells (PSCs), called Somitoids and Segmentoids, which can recapitulate the formation of epithelial somite-like structures with antero-posterior (AP) identity. Using these systems, we identified a key organizing function of the segmentation clock in converting temporal rhythmicity into the spatial regularity of anterior and posterior somitic compartments. We show that an initial salt-and-pepper expression pattern of the segmentation gene MESP2 in the newly formed segment is transformed into defined compartments of anterior and posterior identity via an active cell sorting mechanism. Moreover, we demonstrate a large degree of independence of the various patterning modules involved in somitogenesis including the segmentation clock, somite epithelialization and AP polarity patterning. Together we put forward a novel framework accounting for the symmetry breaking process initiating somite polarity patterning. Our work provides a valuable platform to decode general principles of somitogenesis and advance knowledge of human development.

developmental biology↗

bioRxiv2021

Tension-driven multi-scale self-organisation in human iPSC-derived muscle fibers

Human muscle is a hierarchically organised tissue with its contractile cells called myofibers packed into large myofiber bundles. Each myofiber contains periodic myofibrils built by hundreds of contractile sarcomeres that generate large mechanical forces. To better understand the mechanisms that coordinate human muscle morphogenesis from tissue to molecular scales, we adopted a simple in vitro system using induced pluripotent stem cell-derived human myogenic precursors. When grown on an unrestricted two-dimensional substrate, developing myofibers spontaneously align and self-organise into higher-order myofiber bundles, which grow and consolidate to stable sizes. Following a transcriptional boost of sarcomeric components, myofibrils assemble into chains of periodic sarcomeres that emerge across the entire myofiber. By directly probing tension we found that tension build-up precedes sarcomere assembly and increases within each assembling myofibril. Furthermore, we found that myofiber ends stably attach to other myofibers using integrin-based attachments and thus myofiber bundling coincides with stable myofiber bundle attachment in vitro. A failure in stable myofiber attachment results in a collapse of the myofibrils. Overall, our results strongly suggest that mechanical tension across sarcomeric components as well as between differentiating myofibers is key to coordinate the multi-scale self-organisation of muscle morphogenesis.

developmental biology↗

bioRxiv2021

Metabolic regulation of species-specific developmental rates

Animals display significant inter-specific variation in the rate of embryonic development despite broad conservation of the overall sequence of developmental events. Differences in biochemical reaction speeds, including the rates of protein production and degradation, are thought to be responsible for distinct species-specific rates of development [1-3]. However, the cause of differential biochemical reaction speeds between species remains unknown. Using pluripotent stem cells, we have established an in vitro system that recapitulates the two-fold difference in developmental rate between early mouse and human embryos. This system provides a quantitative measure of developmental speed as revealed by the period of the segmentation clock, a molecular oscillator associated with the rhythmic production of vertebral precursors. Using this system, we showed that mass-specific metabolic rates scale with developmental rate and are therefore elevated in mouse cells compared to human cells. We further showed that reducing these metabolic rates by pharmacologically inhibiting the electron transport chain slows down the segmentation clock. The effect of the electron transport chain on the segmentation clock is mediated by the cellular NAD+/NADH redox balance independent of ATP production and, further downstream, by the global rate of protein synthesis. These findings represent a starting point for the manipulation of developmental rate, which would find multiple translational applications including the acceleration of human pluripotent stem cell differentiation for disease modeling and cell-based therapies.

developmental biology↗

bioRxiv2018

In vitro characterization of the human segmentation clock

The vertebral column is characterized by the periodic arrangement of vertebrae along the anterior-posterior (AP) axis. This segmental or metameric organization is established early in embryogenesis when pairs of embryonic segments called somites are rhythmically produced by the presomitic mesoderm (PSM). The tempo of somite formation is controlled by a molecular oscillator known as the segmentation clock 1,2. While this oscillator has been well characterized in model organisms 1,2, whether a similar oscillator exists in humans remains unknown. We have previously shown that human embryonic stem (ES) cells or induced pluripotent stem (iPS) cells can differentiate in vitro into PSM upon activation of the Wnt signaling pathway combined with BMP inhibition3. Here, we show that these human PSM cells exhibit Notch and YAP-dependent oscillations4 of the cyclic gene HES7 with a 5-hour period. Single cell RNA-sequencing comparison of the differentiating iPS cells with mouse PSM reveals that human PSM cells follow a similar differentiation path and exhibit a remarkably coordinated differentiation sequence. We also demonstrate that FGF signaling controls the phase and period of the oscillator. This contrasts with classical segmentation models such as the \"Clock and Wavefront\" 1,2,5, where FGF merely implements a signaling threshold specifying where oscillations stop. Overall, our work identifying the human segmentation clock represents an important breakthrough for human developmental biology.

developmental biology↗

bioRxiv2017

Distinct effects of tubulin isotype mutations on neurite growth in Caenorhabditis elegans

Tubulins, the building block of microtubules (MTs), play a critical role in both supporting and regulating neurite growth. Eukaryotic genomes contain multiple tubulin isotypes, and their missense mutations cause a range of neurodevelopmental defects. Using the C. elegans touch receptor neurons, we analyzed the effects of 67 tubulin missense mutations on neurite growth. Three types of mutations emerged: 1) loss-of-function mutations, which cause mild defects in neurite growth; 2) antimorphic mutations, which map to the GTP binding site and intradimer and interdimer interfaces, significantly reduce MT stability, and cause severe neurite growth defects; and 3) neomorphic mutations, which map to the exterior surface, increase MT stability, and cause ectopic neurite growth. Structure-function analysis reveals a causal relationship between tubulin structure and MT stability. This stability affects neuronal morphogenesis. As part of this analysis, we engineered several disease-associated human tubulin mutations into C. elegans genes and examined their impact on neuronal development at the cellular level. We also discovered an -tubulin (TBA-7) that appears to destabilize MTs. Loss of TBA-7 led to the formation of hyperstable MTs and the generation of ectopic neurites; the lack of potential sites for polyamination and polyglutamination on TBA-7 may be responsible for this destabilization.\n\nTable of Content (TOC) Highlight SummaryDifferent tubulin isotypes perform different functions in the regulation of MT structure and neurite growth, and missense mutations of tubulin genes have three types of distinct effects on MT stability and neurite growth. One -tubulin isotype appears to induce relative instability due to the lack of potential post-translational modification sites.

cell biology↗