Browsing by Author "Lee-Liu, Dasfne"

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    Cornifelin expression during Xenopus laevis metamorphosis and in response to spinal cord injury
    (2022) Torruella-Gonzalez, Sol; Slater, Paula G.; Lee-Liu, Dasfne; Larrain, Juan
    Background: In a high-throughput RNA sequencing analysis, comparing the transcriptional response between Xenopus laevis regenerative and non-regenerative stages to spinal cord injury, cornifelin was found among the most highly differentially expressed genes. Cornifelin is mainly expressed in stratified squamous epithelia, but its expression in the spinal cord and other central nervous structures has only been described during early development.Results: Here, we report cornifelin expression in the spinal cord, retina, and cornea throughout metamorphosis and in the spinal cord after injury. Cornifelin was detected in the grey matter and meninges of the spinal cord from NF-50 to NF-66, with decreased expression in the grey matter during metamorphosis. In the retina, cor-nifelin was expressed in the ganglion cell layer, the inner and outer nuclear layer, and the outer segment from NF-50 to NF-66. After spinal cord injury, we only observed cornifelin upregulation in NF-66 but no significant changes in NF-50. However, we found cornifelin positive cells in NF-50 meninges closing the spinal cord stumps 1 day after injury and delineating the borders of the spinal cord following the continuity of tissue regeneration in the following days after injury. Instead, in NF-66, cornifelin positive cells were distributed to the ventral side of the spinal cord at 6 days after injury, and at the injury gap at 10 days after injury.Conclusions: Cornifelin is expressed in the Xenopus laevis spinal cord and eye during metamorphosis and plays a role in the meningeal response to spinal cord injury.
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    Expression of Transposable Elements in Neural Tissues during Xenopus Development
    (2011) Faunes, Fernando; Sanchez, Natalia; Moreno, Mauricio; Olivares, Gonzalo H.; Lee-Liu, Dasfne; Almonacid, Leonardo; Slater, Alex W.; Norambuena, Tomas; Taft, Ryan J.; Mattick, John S.; Melo, Francisco; Larrain, Juan
    Transposable elements comprise a large proportion of animal genomes. Transposons can have detrimental effects on genome stability but also offer positive roles for genome evolution and gene expression regulation. Proper balance of the positive and deleterious effects of transposons is crucial for cell homeostasis and requires a mechanism that tightly regulates their expression. Herein we describe the expression of DNA transposons of the Tc1/mariner superfamily during Xenopus development. Sense and antisense transcripts containing complete Tc1-2_Xt were detected in Xenopus embryos. Both transcripts were found in zygotic stages and were mainly localized in Spemann's organizer and neural tissues. In addition, the Tc1-like elements Eagle, Froggy, Jumpy, Maya, Xeminos and TXr were also expressed in zygotic stages but not oocytes in X. tropicalis. Interestingly, although Tc1-2_Xt transcripts were not detected in Xenopus laevis embryos, transcripts from other two Tc1-like elements (TXr and TXz) presented a similar temporal and spatial pattern during X. laevis development. Deep sequencing analysis of Xenopus tropicalis gastrulae showed that PIWI-interacting RNAs (piRNAs) are specifically derived from several Tc1-like elements. The localized expression of Tc1-like elements in neural tissues suggests that they could play a role during the development of the Xenopus nervous system.
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    Neurod4 converts endogenous neural stem cells to neurons with synaptic formation after spinal cord injury
    (2021) Fukuoka, Toshiki; Kato, Akira; Hirano, Masaki; Ohka, Fumiharu; Aoki, Kosuke; Awaya, Takayuki; Adilijiang, Alimu; Sachi, Maeda; Tanahashi, Kuniaki; Yamaguchi, Junya; Motomura, Kazuya; Shimizu, Hiroyuki; Nagashima, Yoshitaka; Ando, Ryo; Wakabayashi, Toshihiko; Lee-Liu, Dasfne; Larrain, Juan; Nishimura, Yusuke; Natsume, Atsushi
    The transcriptome analysis of injured Xenopus laevis tadpole and mice suggested that Neurod4L.S., a basic-helix-loop-helix transcription factor, was the most promising transcription factor to exert neuroregeneration after spinal cord injury (SCI) in mammals. We generated a pseudotyped retroviral vector with the neurotropic lymphocytic choriomeningitis virus (LCMV) envelope to deliver murine Neurod4 to mice undergoing SCI. SCI induced ependymal cells to neural stem cells (NSCs) in the central canal. The LCMV envelope-based pseudotypedvector preferentially introduced Neurod4 into activated NSCs, which converted to neurons with axonal regrowth and suppressed the scar-forming glial lineage. Neurod4-induced inhibitory neurons predominantly projected to the subsynaptic domains of motor neurons at the epicenter, and Neurod4-induced excitatory neurons predominantly projected to subsynaptic domains of motor neurons caudal to the injury site suggesting the formation of functional synapses. Thus, Neurod4 is a potential therapeutic factor that can improve anatomical and functional recovery after SCI.
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    Spinal cord regeneration in Xenopus laevis
    (2017) Edwards Faret, Gabriela Andrea; Valle Muñoz Videla, Rosana del; Mendez Olivos, Emilio E.; Lee-Liu, Dasfne; Tapia, Victor S.; Larraín Correa, Juan Agustín
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    The African clawed frog Xenopus laevis: A model organism to study regeneration of the central nervous system
    (2017) Lee-Liu, Dasfne; Méndez, Emilio E.; Muñoz, Rosana; Larraín Correa, Juan Agustín