FGF independent MEK1/2 signalling is essential for male germline development in mice

Blucher, R. O.; Lim, R. S.; Jarred, E. G.; Ritchie, M. E.; Western, P. S.

doi:10.1101/2023.02.05.527224

Home/Archive/bioRxiv

bioRxiv · 10.1101/2023.02.05.527224

FGF independent MEK1/2 signalling is essential for male germline development in mice

Blucher, R. O.·Lim, R. S.·Jarred, E. G.·Ritchie, M. E.·Western, P. S.

View original source ↗Export metadata ↓

Abstract

BackgroundGermline development provides the founding cells for spermatogenesis and oogenesis in males and females, respectively. Disrupted germline differentiation or compromised testis development can lead to subfertility or infertility and are strongly associated with testis cancer in humans. In mice, SRY and SOX9 induce expression of a range of genes, including Fgf9, that promote Sertoli cell differentiation and testis development. FGF9 is also thought to promote male germline differentiation but the pathway through which it signals is unknown. As FGFs signal through Mitogen-Activated Protein Kinases (MAPKs) in other tissues, we explored whether FGF9 regulates male germline development through MAPK by inhibiting either FGF or MEK1/2 signalling in fetal testis cultures from embryonic day (E)12.5, immediately after gonadal sex determination and testis cord formation, but prior to male germline commitment. ResultsInhibition of MEK1/2 disrupted mitotic arrest, dysregulated a broad range of male germline development genes and prevented the upregulation of key male germline markers DPPA4 and DNMT3L. In contrast, when FGF signalling was inhibited, the male germline specific transcriptional program and the expression of male germline markers DPPA4 and DNMT3L were unaffected, and germ cells entered mitotic arrest normally. While male germline development was not disrupted by FGF inhibition, some genes were commonly altered after 24h of FGF or MEK1/2 inhibition including genes involved in maintenance, germline stem cells, Nodal signalling, proliferation, and germline cancer. ConclusionsTogether, these data demonstrate a novel and essential role for MEK1/2 signalling in male germline differentiation, but a more limited role for FGF signalling. Our data strongly indicate that additional ligands act through MEK1/2 to promote male germline differentiation and highlight a need for further mechanistic understanding of male germline development.

Explore related subjects

developmental biology Preprint

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Blucher, R. O., Lim, R. S., Jarred, E. G., Ritchie, M. E., Western, P. S.. 2023-02-08. FGF independent MEK1/2 signalling is essential for male germline development in mice. https://doi.org/10.1101/2023.02.05.527224

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

KEEP EXPLORING

Related preprints

bioRxiv2026

Hyaluronic acid dynamics are regulated by neural crest cells and NEDD4 in the developing cardiac outflow tract valves

The extracellular matrix (ECM) is essential for cardiac valve development, with hyaluronic acid (HA) playing a critical role in cardiac cushion formation. While HA is required for atrioventricular valve development, its role in semilunar valve formation remains poorly understood. The ubiquitin ligase NEDD4 is essential for cardiac outflow tract development, particularly within cardiac neural crest cells, however its role in semilunar valve development has been unexplored. Here, we demonstrate that neural crest-specific deletion of NEDD4 in mice disrupts outflow tract valve development, resulting in abnormal leaflet number and morphology. Analysis of valve ECM revealed a specific reduction in HA within the neural crest-derived valve mesenchyme, while other ECM components such as fibronectin and versican remained unaffected. In contrast, deletion of NEDD4 in endocardium-derived valve mesenchyme did not alter HA abundance. Using NEDD4-deficient neural crest cells, we further demonstrate a cell-autonomous requirement for NEDD4 in regulating HA abundance, with in vitro evidence supporting impaired HA synthesis rather than increased turnover of HA in the ECM. Our findings identify a previously unrecognised role for NEDD4 in regulating HA synthesis in cardiac neural crest cells, revealing a cell-type-specific mechanism governing semilunar valve development and highlighting distinct cellular requirements for ECM regulation across cardiac valve populations.

developmental biology↗

bioRxiv2026

Endogenous Mechanical Reporters Encode the Global Mechanical Landscape of Morphogenesis

Developmental systems usually comprise multiple genetically programmed morphogenetic events within a mechanically continuous environment, yet how individual processes interact and contribute to the overall mechanical landscape remains unknown. Here, we introduce the concept of mechanical reporter: endogenous tissues function as in situ probes of the embedded mechanical landscape. We exemplified cephalic furrow (CF) migration as a mechanical reporter in gastrulating Drosophila. Using optogenetics and genetics, we revealed that CF displacement reflects the combined effect of both force and tissue mechanical properties. By incorporating condition-specific mechanical landscape into a continuum minimal-response model, we developed a framework to quantitatively predict the reporter dynamics. Using different genetic mutants, we successfully decoded changes in the mechanical landscape from CF dynamics in gastrulating Drosophila. Overall, we established a predictive framework that uses CF dynamics to infer changes in the global mechanical landscape. Beyond this, the concept of mechanical reporter provides a general strategy for systematically understanding and decoding complex mechanical environments in living systems.

developmental biology↗

bioRxiv2026

Dissecting human embryonic patterning during organogenesis reveals a rostral midline progenitor population for mesoendoderm induction

Understanding how human organogenesis is accomplished via intricate spatiotemporal patterning of organ primordia requires spatial atlases at cellular resolution. However, existing human embryo spatial atlases are built using sequencing-based platforms such as Stereo-seq, which have limited spatial resolution and blurred anatomical boundaries, leading to misclassification across adjacent cells. Here, we integrate in situ imaging-based transcriptomics (Xenium) with transcriptome-wide spatial profiling (Visium-HD) of Carnegie stages 9-12 embryos to delineate the patterning of core embryonic tissues at single-cell resolution, including the brain, spinal cord, somites, neural crest, notochord, heart, and gut tube. A new finding enabled by spatial single-cell resolution is the identification of rostral midline progenitors (RMPs), a cell population co-expressing SOX2, TBXT, and OTX2. Transcriptionally, RMPs are distinct from both neuromesodermal progenitors (NMPs) and prechordal mesoderm, and in vivo clonal barcoding in mice indicates that RMPs share a common developmental origin with rostral neural ectoderm. To interrogate their functional significance, we leveraged our spatial transcriptome data to recapitulate RMP-like cells from human pluripotent stem cells and showed that these cells can induce epiblast-like cells to acquire mesendodermal and endodermal fates, while themselves adopting an ectodermal fate consistent with their in vivo counterparts. This work provides a 3D, stage-resolved molecular cell atlas of tissue patterning in human embryo that serves as a reference for in vitro models.

developmental biology↗