Loading...
2 results
Search Results
Now showing 1 - 2 of 2
- Cell–fibronectin interactions and actomyosin contractility regulate the segmentation clock and spatio-temporal somite cleft formation during chick embryo somitogenesisPublication . Gomes De Almeida, Patrícia; Rifes, Pedro; Jesus, Ana Patrícia; Pinheiro, Gonçalo; P. Andrade, Raquel; Thorsteinsdóttir, SólveigFibronectin is essential for somite formation in the vertebrate embryo. Fibronectin matrix assembly starts as cells emerge from the primitive streak and ingress in the unsegmented presomitic mesoderm (PSM). PSM cells undergo cyclic waves of segmentation clock gene expression, followed by Notch-dependent upregulation of meso1 in the rostral PSM which induces somite cleft formation. However, the relevance of the fibronectin matrix for these molecular processes remains unknown. Here, we assessed the role of the PSM fibronectin matrix in the spatio-temporal regulation of chick embryo somitogenesis by perturbing (1) extracellular fibronectin matrix assembly, (2) integrin–fibronectin binding, (3) Rho-associated protein kinase (ROCK) activity and (4) non-muscle myosin II (NM II) function. We found that integrin–fibronectin engagement and NM II activity are required for cell polarization in the nascent somite. All treatments resulted in defective somitic clefts and significantly perturbed meso1 and segmentation clock gene expression in the PSM. Importantly, inhibition of actomyosin-mediated contractility increased the period of hairy1/hes4 oscillations from 90 to 120 min. Together, our work strongly suggests that the fibronectin–integrin–ROCK–NM II axis regulates segmentation clock dynamics and dictates the spatio-temporal localization of somitic clefts.
- Rewired glycosylation activity promotes scarless regeneration and functional recovery in spiny mice after complete spinal cord transectionPublication . Nogueira-Rodrigues, Joana; Leite, Sérgio C.; Pinto-Costa, Rita; Sousa, Sara C.; Luz, Liliana L.; Sintra, Maria A.; Oliveira, Raquel; Monteiro, Ana C.; Pinheiro, Gonçalo; Vitorino, Marta; Silva, Joana A.; S, Simão; Vitor Fernandes, Dr; Provazník, Jan; Benes, Vladimir; Cruz, Célia D.; Safronov, Boris V.; Magalhães, Ana; Reis, Celso A.; Vieira, Jorge; Vieira, Cristina P.; Tiscórnia, Gustavo; Araujo, Ines; Sousa, Mónica M.Regeneration of adult mammalian central nervous system (CNS) axons is abortive, resulting in inability to recover function after CNS lesion, including spinal cord injury (SCI). Here, we show that the spiny mouse (Acomys) is an exception to other mammals, being capable of spontaneous and fast restoration of function after severe SCI, re-establishing hind limb coordination. Remarkably, Acomys assembles a scarless pro-regenerative tissue at the injury site, providing a unique structural continuity of the initial spinal cord geometry. The Acomys SCI site shows robust axon regeneration of multiple tracts, synapse formation, and electrophysiological signal propagation. Transcriptomic analysis of the spinal cord following transcriptome reconstruction revealed that Acomys rewires glycosylation biosynthetic pathways, culminating in a specific pro-regenerative proteoglycan signature at SCI site. Our work uncovers that a glycosylation switch is critical for axon regeneration after SCI and identifies beta 3gnt7, a crucial enzyme of keratan sulfate biosynthesis, as an enhancer of axon growth.