The department deals with research into the genetic regulation of embryonic development. In our studies, we use tissue-specific gene inactivation (knock‑out) technologies in mice using the Cre-loxP system. We study the functions of Wnt, Shh and FGF signaling pathways and selected transcription factors, e.g. from the Meis, Hand and Pbx families. We focus on the differentiation of neural crest cells and the associated germinal development of cartilage and bone in the craniofacial area and the middle ear. We also study the cellular mechanisms of neural tissue formation derived from neural crest cells. Analyses in mouse models are complemented by experiments in Danio rerio fish embryos. In both experimental organisms, we try to clarify the genetic nature of some human developmental defects.
Mesenchymal Meis2 controls whisker development independently from trigeminal sensory innervation
Hair follicle development is initiated by reciprocal molecular interactions between the placodeforming epithelium and the underlying mesenchyme. Here we show that Meis2 expression in cells derived from the neural crest is critical for whisker formation and for branching of trigeminal nerves. Meis2 in mesenchymal dermal cells orchestrates the initial steps of epithelial placode formation and subsequent dermal condensation by regulating Foxd1 expression which is typical of pre-dermal condensation.
Severed whisker follicle development in Meis2 cKO embryos. (A) micro-CT images of control and Meis2 cKO embryos showing aberrant whisker phenotype in Meis2 cKO mice. (B) Light-sheet microscopy of Sox9 whole-mount immunostaining of WF. (C) MEIS2 immunofluorescence on frontal frozen sections (D) Wnt1-Cre; mTmG embryos showing Cre recombination specificity (green) in the craniofacial area, midbrain and dorsal spinal cord. (E) Frontal sections of Wnt1-Cre; mTmG snouts documenting Cre recombination in the neural crest-derive mesenchyme, cranial nerve projections without recombination in the overlying epithelium. (F) Whole-mount staining with SOX9 and TRKA (Ntrk1) antibodies showing the almost absence of WF and compromised branching of the trigeminal nerve.
Publication:
Kaplan M. M., Hudacova E., Matejcek M., Tuaima H., Krivanek J., Machon O.: (2024) Mesenchymal Meis2 controls whisker development independently from trigeminal sensory innervation. Elife, https://doi.org/10.7554/eLife.100854.1
Single-cell transcriptomic resolution of osteogenesis during craniofacial morphogenesis
We performed single-cell transcriptomic analysis of craniofacial mesenchymal cells derived from neural crest cells and mapped the cell heterogeneity during the initial stages of cartilage and bone formation. We identified molecular determinants of cell populations involved in the development of lower and upper jaw, teeth, tongue, or dermis. Analysis of Meis2-deficient mice revealed increased osteogenesis and cell adhesion leading to abnormal mesenchymal condensation and impaired bone and cartilage.
Absence of Meis2 in cranial neural crest cells affects mesenchymal cell populations associated with osteogenesis and tongue formation. (A) UMAP plots of 21 mesenchymal clusters showing changes between Wnt1-Cre2; Meis2 fl/fl (Meis2 cKO) and control. (B) Cell numbers across 21 clusters in controls and Meis2. (C) Violin plot illustrating Meis2 expression across 21 clusters (*). (D) Venn diagram displaying differentially expressed genes. (E) Volcano plots showing differentially expressed genes (F) Top: Alcian/Alizarin staining of controls and Meis2 cKOs at E17.5. Ventral/side view of the head showing fusion and shortening of premaxilla and maxilla (white arrowheads), cleft palate (*), shrunken basisphenoid bone (black arrowheads) and tympanic rings (white double arrowheads). Middle: shorter and wider mandible in Meis2 cKO. Bottom: Frontal sections at E16.5 showing cleft palate (p*), hypoglossia (t*), and aberrant ossification of the mandible (mb*).
Publication:
Hudacova E., Abaffy P., Kaplan M. M., Krausova M., Kubista M., Machon O.: (2024) Single-cell transcriptomic resolution of osteogenesis during craniofacial morphogenesis. Bone 2024 Oct 24:190:117297. doi: 10.1016/j.bone.2024.117297. PMID: 39461490
Meis2 controls skeletal formation in the hyoid region
We identified Meis2 as a critical transcription factor determining embryonic bone formation. In the hyoid bone, we showed that mesenchymal condensation, chondroblast proliferation and their spatial arrangement is driven by transcription factor Meis2.
Elevated proliferation of SOX9 cells in the cartilage primordium of the hyoid bone in Wnt1-Cre2; Meis2 f/f. (A-C’) Frontal frozen sections with orthogonal projections of hyoid regions in controls and Wnt1-Cre2; Meis2 f/f. (D) Quantifications of the percentage of double positive EdU/SOX9 cells in controls and Wnt1-Cre2; Meis2 f/f.
Publication:
Fábik, J., Psutková, V., Machoň, O.: (2022) Meis2 controls skeletal formation in the hyoid region. Frontiers in Cell and Developmental Biology. 28(10): 951063. doi: 10.3389/fcell.2022.951063
MEIS-WNT5A axis regulates development of fourth ventricle choroid plexus
The choroid plexus (ChP) produces cerebrospinal fluid and forms an essential brain barrier. ChP tissues form in each brain ventricle. Epithelial WNT5A is crucial for determining fourth ventricle (4V) ChP morphogenesis and size in mouse. WNT5A, which depends on transcription factors Meis1 and eis2, acts locally to activate non-canonical WNT signaling via ROR1 and ROR2 receptors.
WNT5A signaling in the embryonic ChP epithelium. Epithelial WNT5A, production of which is under direct regulatory control of the transcription co-factor MEIS1, stimulates in an autocrine manner the transmembrane receptors ROR1 and ROR2. Their activation leads to the activation of DVL2 and DVL3.
Publication:
Kaiser, K., Jang, A., Kompanikova, P., Lun-Melody, P., Procházka, J., Machoň, O., Dani, N., Procházková, M., Laurent, B., Gyllborg, D., van Amerongen, R., Fame, R.M., Gupta, S., Wu, F., Barker, R.A., Buková, I., Sedláček, R., Kozmik, Z., Arenas, E., Lehtinen, M.K.: (2021) MEIS-WNT5A axis regulates development of fourth ventricle choroid plexus. Development. 148(10): dev192054. doi: 10.1242/dev.192054.
Projects
2022–2024
The role of Meis transcription factors in mesenchymal condensations during formation of the cranium
Department of Developmental BiologyKaplan M.Zeidler M.Knapp A.Hölzl M.Kress M.Fritsch H.Krogsdam A.Flucher B. E.
2024
iScience. 2024 May 17;27(6):110018. doi: 10.1016/j.isci.2024.110018. eCollection 2024 Jun 21.
2024
eLife13:RP100854 https://doi.org/10.7554/eLife.100854.1
