Regulation of neuronal gene expression by epi-editing

Trabajo presentado al Online Seminar: Molecular Neurobiolgy and Neuropathology, celebrado el 29 de septiembre de 2020.Peer reviewe

Comprehensive expression analysis for the core cell cycle regulators in the chicken embryo reveals novel tissue-specific synexpression groups and similarities and differences with expression in mouse, frog and zebrafish

The core cell cycle machinery is conserved from yeast to humans, and hence it is assumed that all vertebrates share the same set of players. Yet during vertebrate evolution, the genome was duplicated twice, followed by a further genome duplication in teleost fish. Thereafter, distinct genes were retained in different vertebrate lineages; some individual gene duplications also occurred. To which extent these diversifying tendencies were compensated by retaining the same expression patterns across homologous genes is not known. This study for the first time undertook a comprehensive expression analysis for the core cell cycle regulators in the chicken, focusing in on early neurula and pharyngula stages of development, with the latter representing the vertebrate phylotypic stage. We also compared our data with published data for the mouse, Xenopus and zebrafish, the other established vertebrate models. Our work shows that, while many genes are expressed widely, some are upregulated or specifically expressed in defined tissues of the chicken embryo, forming novel synexpression groups with markers for distinct developmental pathways. Moreover, we found that in the neural tube and in the somite, mRNAs of some of the genes investigated accumulate in a specific subcellular localisation, pointing at a novel link between the site of mRNA translation, cell cycle control and interkinetic nuclear movements. Finally, we show that expression patterns of orthologous genes may differ in the four vertebrate models. Thus, for any study investigating cell proliferation, cell differentiation, tissue regeneration, stem cell behaviour and cancer/cancer therapy, it has to be carefully examined which of the observed effects are due to the specific model organism used, and which can be generalised.The work was funded by a UoP start-up grant, an IBBS studentship to Federica. Berti and an Erasmus fellowship to Marta Alaiz Noya.Peer reviewe

Transcriptome and epigenome analysis of engram cells: Next-generation sequencing technologies in memory research

Transcription and epigenetic changes are integral components of the neuronal response to stimulation and have been postulated to be drivers or substrates for enduring changes in animal behavior, including learning and memory. Memories are thought to be deposited in neuronal assemblies called engrams, i.e., groups of cells that undergo persistent physical or chemical changes during learning and are selectively reactivated to retrieve the memory. Despite the research progress made in recent years, the identity of specific epigenetic changes, if any, that occur in these cells and subsequently contribute to the persistence of memory traces remains unknown. The analysis of these changes is challenging due to the difficulty of exploring molecular alterations that only occur in a relatively small percentage of cells embedded in a complex tissue. In this review, we discuss the recent advances in this field and the promise of next-generation sequencing (NGS) and epigenome editing methods for overcoming these challenges and address long-standing questions concerning the role of epigenetic mechanisms in memory encoding, maintenance and expression.M.F.-R. is the recipient of a “Formación de Profesorado Universitario (FPU)” fellowship from the Spanish Ministry of Education and M.A.-N. is the recipient of an ACIF fellowship from Generalitat Valenciana. A.B. research is supported by grants SAF2017-87928-R and SEV-2013-0317 from MICINN co-financed by ERDF, grant PROMETEO/2020/007 from the Generalitat Valenciana, and grant RGP0039/2017 from the Human Frontiers Science Program Organization (HFSPO). The Instituto de Neurociencias is a “Centre of Excellence Severo Ochoa”.Peer reviewe

Characterization of an eutherian gene cluster generated after transposon domestication identifies Bex3 as relevant for advanced neurological functions

Background One of the most unusual sources of phylogenetically restricted genes is the molecular domestication of transposable elements into a host genome as functional genes. Although these kinds of events are sometimes at the core of key macroevolutionary changes, their origin and organismal function are generally poorly understood. Results Here, we identify several previously unreported transposable element domestication events in the human and mouse genomes. Among them, we find a remarkable molecular domestication that gave rise to a multigenic family in placental mammals, the Bex/Tceal gene cluster. These genes, which act as hub proteins within diverse signaling pathways, have been associated with neurological features of human patients carrying genomic microdeletions in chromosome X. The Bex/Tceal genes display neural-enriched patterns and are differentially expressed in human neurological disorders, such as autism and schizophrenia. Two different murine alleles of the cluster member Bex3 display morphological and physiopathological brain modifications, such as reduced interneuron number and hippocampal electrophysiological imbalance, alterations that translate into distinct behavioral phenotypes. Conclusions We provide an in-depth understanding of the emergence of a gene cluster that originated by transposon domestication and gene duplication at the origin of placental mammals, an evolutionary process that transformed a non-functional transposon sequence into novel components of the eutherian genome. These genes were integrated into existing signaling pathways involved in the development, maintenance, and function of the CNS in eutherians. At least one of its members, Bex3, is relevant for higher brain functions in placental mammals and may be involved in human neurological disorders.Major financial support for this research was received from Spanish “Ministerio de Ciencia, Innovación y Universidades.” Grants BFU2015-68655-P and BFU2017-861152-P to J.G.F., RTI2018-100968-B-I00, 2017-SGR-738, H2020/2014-2020 under grant agreements n°667302, n°643051, and n°728018 to B.C., PGC2018-098229-B-I00 to J.L.F., BES-2016-077374 to E.A.-G., CVI-7290 Junta de Andalucía to A.R.M., SAF2016-80937-R (Ministerio de Economía y Competitividad/FEDER) to G.M., Institutional Grant MDM-2016-0687 (Maria de Maeztu Excellence Unit, Department of Gene Regulation and Morphogenesis at CABD) and BFU2017-83150-P to J.J.C, BFU2017-89780-R and P12-CTS-2257 to A.M.C. and SAF2016-76340-R and María de Maeztu Excellence Unit, Institute of Neurosciences to E.S.. E.N.P. held an FPI pre-doctoral fellowship (Spanish “Ministerio de Ciencia, Innovación y Universidades”). S.M. was first supported by a contract with the “Centro de Investigación Biomédica en Enfermedades Neurodegenerativas,” and later by “Centro de Investigación Biomédica en Red de Enfermedades Raras” (CIBERER). N.F.C. is also under contract by CIBERER. This study makes use of data generated by the DECIPHER community. A full list of centres who contributed to the generation of the data is available at http://decipher.sanger.ac.uk and via email from [email protected]. Funding for the project was provided by the Wellcome Trust.Ye