Caracterización de la familia génica LGI

La epilepsia lateral temporal de herencia autosómica dominante, es una forma de epilepsia parcial, con crisis secundariamente generalizadas, causada por mutaciones en LGI1. Este gen fue inicialmente descrito en 1998 en relación a la aparición de glioblastomas malignos y se ha visto que su expresión, se relaciona inversamente con el grado de malignidad de estos tumores. El análisis in silico de la secuencia primaria de LGI1, permitió identificar una familia génica compuesta por cuatro elementos, que compartían una misma organización en dominios proteicos: la familia LGI. La existencia de formas clínicas de epilepsia similares a aquellas debidas a mutaciones en LGI1 pero sin relación con este gen, permite establecer la hipótesis de que algún otro componente de la misma familia génica podría estar implicado en la aparición de la enfermedad. Además, la existencia de varios parálogos sugiere que se da un cierto grado de redundancia funcional, que podría ser explicado por una distinta distribución anatómica de los elementos de la familia LGI. En este trabajo se presentan los resultados del análisis de expresión de los ARNm de los componentes de la familia LGI en cerebro de ratón adulto. La distribución de transcritos de los genes de la familia LGI es regionalmente heterogénea, lo que hace pensar que desde su origen a partir de un gen ancestral común, sufrieron una subfuncionalización. Además, en este trabajo se trata de indagar, en la posible función o funciones de estos genes.Autosomic dominant lateral temporal epilepsy (ADLTE) is a form of partial epilepsy with secondary generalized seizures, caused by mutations in LGI1. This gene was initially identified in 1998, as a tumour suppressor in multiform glioblastoma, affecting to the malignancy of these tumours. In silico analysis of the primary sequence of LGI1, revealed four paralogues of the gene, which shared a very similar domain structure and were named as LGI1, LGI2, LGI3 and LGI4. The existence of similar types of epilepsy with common features for that seen for ADLTE, suggests that some other members of this gene family could be involved in these pathologies. Moreover, the presence of four paralogues, makes the idea of a certain degree of functional redundancy, possible. This fact, could be explained by the complementary distribution of cells expressing the genes of this family in the brain. In this work, we show a detailed expression analysis of the mRNA of the members of the LGI family in adult mouse brain. The distribution of these genes is regionally heterogeneous, suggesting that since their origin as a common ancestral gene, a subfunctionalization might have occurred. In this work, we try to shed light on these possible functions

Editorial: New insights into adult neurogenesis and neurodegeneration: challenges for brain repair

The formation of new neurons in the brain is probably one of the most controversial topics in the scientific community since in the 1960's Joseph Altman described for the first time that proliferating cells give rise to new neurons in the adult brain of rats and other mammals. This Research Topic includes 1 brief research report, 3 mini review, 4 review and 9 original research papers gathering different contributions highlighting new developments in the field of neurogenesis

Regional distribution of the leucine-rich glioma inactivated (LGI) gene family transcripts in the adult mouse brain

25 p., figuras y bibliografíaThe leucine-rich glioma inactivated (LGI) gene subfamily contains four highly conserved members (LGI1, 2, 3 and 4), which have been described in human, mouse and other mammalians. Although their main roles remain unknown, LGI1 gene mutations have been found in human partial temporal lobe epilepsy. Moreover, previous studies showed that the products of these genes exert their function in the nervous system. The anatomical distribution of these gene transcripts in the brain might give some insight to elucidate their possible function. In this study, the pattern of expression of the four LGI genes was assessed in the brain of C57BL/6J adult mice by in situ hybridization. We found that the LGI1 transcript is mainly expressed in the dentate gyrus and CA3 field of the hippocampus. LGI2 and LGI4 genes, which showed a similar pattern of distribution with minor differences, were mostly expressed in the medial septal area, thalamic reticular nucleus and substantia nigra pars compacta. LGI3-expressing cells were distributed widespread, but were more consistently observed in the hippocampal formation, thalamic and hypothalamic nuclei, substantia nigra and reticular formation. In summary, LGI1 gene expression is very restricted to intrahippocampal circuitry, which might be related to its involvement in temporal lobe epilepsy. The patterns of expression of LGI2 and LGI4 genes are very similar and their distribution in the vertical limb of the diagonal band and in putative hippocampal interneurons, suggest that the function of these genes might be related to the generation of hippocampal theta rhythm. Finally, LGI3 gene widespread expression in the brain suggests that its transcripts might be involved in a common cellular process present in different neuronal types.This work was supported by a grant from the Ministerio de Educación y Ciencia (SAF2006-00724) to J. P-T. Part of F. O-B. work has been supported by the Spanish Health Department (FIS 06-1816).Peer reviewe

Ultrastructural characterization of human oligodendrocytes and their progenitor cells by pre-embedding immunogold.

Oligodendrocytes are the myelinating cells of the central nervous system. They provide trophic, metabolic, and structural support to neurons. In several pathologies such as multiple sclerosis (MS), these cells are severely affected and fail to remyelinate, thereby leading to neuronal death. The gold standard for studying remyelination is the g-ratio, which is measured by means of transmission electron microscopy (TEM). Therefore, studying the fine structure of the oligodendrocyte population in the human brain at different stages through TEM is a key feature in this field of study. Here we study the ultrastructure of oligodendrocytes, its progenitors, and myelin in 10 samples of human white matter using nine different markers of the oligodendrocyte lineage (NG2, PDGFRα, A2B5, Sox10, Olig2, BCAS1, APC-(CC1), MAG, and MBP). Our findings show that human oligodendrocytes constitute a very heterogeneous population within the human white matter and that its stages of differentiation present characteristic features that can be used to identify them by TEM. This study sheds light on how these cells interact with other cells within the human brain and clarify their fine characteristics from other glial cell types

Editorial: Mesenchymal stromal cell therapy for regenerative medicine

Mesenchymal stromal/stem cell (MSC) therapies are increasingly explored as novel regenerative and immunomodulatory approaches to treat or prevent diseases (Pittenger et al., 2019; Hmadcha et al., 2020; Moll et al., 2020b; Ringdén et al., 2022). These cells exhibit potent paracrine properties that can modulate host immune responses, lower inflammation, and orchestrate endogenous tissue repair, at both the local and the systemic level through multiple pathways (Singer and Caplan, 2011; Doorn et al., 2012). MSCs possess tropism toward damaged and inflamed tissues, where they can engraft short-term and exert their therapeutic effects by both direct and indirect mechanisms (Doorn et al., 2012; Galipeau and Sensebe, 2018; Soria et al., 2019). MSC products can be prepared from multiple sources (Moll et al., 2019, 2022), rapidly expanded and biobanked for clinical application. All these advantages make this cell type a versatile tool in regenerative medicine. The goal of our Research Topic is to highlight the latest advances in applications of MSCs for the treatment of a variety of diseases and their modes of action (MoA). A better understanding of the mechanisms underlying the therapeutic effect of MSCs can provide crucial insight into innovative strategies to enhance their effectiveness in clinical application (Singer and Caplan, 2011; Doorn et al., 2012; Galipeau and Sensebe, 2018; Moll et al., 2019, 2020b, 2022; Pittenger et al., 2019; Ringdén et al., 2022). The subjects covered within this Research Topic include: (a) Therapeutic application of MSCs for major clinical indications, (b) Cellular and molecular mechanisms underlying therapeutic effects of MSCs, and (c) Strategies for enhancement of the therapeutic effects of MSCs and their products. Here, we summarize the 37 manuscripts that were submitted to this Research Topic (Figure 1)

Ependymoma associated protein Zfta is expressed in immature ependymal cells but is not essential for ependymal development in mice

The fusion protein of uncharacterised zinc finger translocation associated (ZFTA) and effector transcription factor of tumorigenic NF‑κB signalling, RELA (ZFTA‑RELA), is expressed in more than two‑thirds of supratentorial ependymoma (ST‑EPN‑RELA), but ZFTA¿s expression profile and functional analysis in multiciliated ependymal (E1) cells have not been examined. Here, we showed the mRNA expression of mouse Zfta peaks on embryonic day (E) 17.5 in the wholemount of the lateral walls of the lateral ventricle. Zfta was expressed in the nuclei of FoxJ1‑positive immature E1 (pre‑E1) cells in E18.5 mouse embryonic brain. Interestingly, the transcription factors promoting ciliogenesis (ciliary TFs) (e.g., multicilin) and ZFTA‑RELA upregulated luciferase activity using a 5′ upstream sequence of ZFTA in cultured cells. Zftatm1/tm1 knock‑in mice did not show developmental defects or abnormal fertility. In the Zftatm1/tm1 E1 cells, morphology, gene expression, ciliary beating frequency and ependymal flow were unaffected. These results suggest that Zfta is expressed in pre‑E1 cells, possibly under the control of ciliary TFs, but is not essential for ependymal development or flow. This study sheds light on the mechanism of the ZFTA‑RELA expression in the pathogenesis of ST‑EPNRELA: Ciliary TFs initiate ZFTA‑RELA expression in pre‑E1 cells, and ZFTA‑RELA enhances its own expression using positive feedback

Dynamic Changes in the Neurogenic Potential in the Ventricular–Subventricular Zone of Common Marmoset during Postnatal Brain Development

Even after birth, neuronal production continues in the ventricular–subventricular zone (V–SVZ) and hippocampus in many mammals. The immature new neurons (“neuroblasts”) migrate and then mature at their final destination. In humans, neuroblast production and migration toward the neocortex and the olfactory bulb (OB) occur actively only for a few months after birth and then sharply decline with age. However, the precise spatiotemporal profiles and fates of postnatally born neurons remain unclear due to methodological limitations. We previously found that common marmosets, small nonhuman primates, share many features of V–SVZ organization with humans. Here, using marmosets injected with thymidine analogue(s) during various postnatal periods, we demonstrated spatiotemporal changes in neurogenesis during development. V–SVZ progenitor proliferation and neuroblast migration toward the OB and neocortex sharply decreased by 4 months, most strikingly in a V–SVZ subregion from which neuroblasts migrated toward the neocortex. Postnatally born neurons matured within a few months in the OB and hippocampus but remained immature until 6 months in the neocortex. While neurogenic activity was sustained for a month after birth, the distribution and/or differentiation diversity was more restricted in 1-month-born cells than in the neonatal-born population. These findings shed light on distinctive features of postnatal neurogenesis in primates

Endoderm development requires centrioles to restrain p53-mediated apoptosis in the absence of ERK activity

Centrioles comprise the heart of centrosomes, microtubule-organizing centers. To study the function of centrioles in lung and gut development, we genetically disrupted centrioles throughout the mouse endoderm. Surprisingly, removing centrioles from the endoderm did not disrupt intestinal growth or development but blocked lung branching. In the lung, acentriolar SOX2-expressing airway epithelial cells apoptosed. Loss of centrioles activated p53, and removing p53 restored survival of SOX2-expressing cells, lung branching, and mouse viability. To investigate how endodermal p53 activation specifically killed acentriolar SOX2-expressing cells, we assessed ERK, aprosurvival cue.ERKwasactivethroughouttheintestine and inthedistal lung buds, correlating with tolerance to centriole loss. Pharmacologically inhibiting ERK activated apoptosis in acentriolar cells, revealing that ERK activity protects acentriolar cells from apoptosis. Therefore, centrioles are largely dispensable for endodermal growth and the spatial distribution of ERK activity in the endoderm shapes the developmental consequences of centriolar defects and p53 activation

Adult neurogenesis in the telencephalon of the lizard Podarcis liolepis

In adult lizards, new neurons are generated from neural stem cells in the ventricular zone of the lateral ventricles. These new neurons migrate and integrate into the main telencephalic subdivisions. In this work we have studied adult neurogenesis in the lizard Podarcis liolepis (formerly Podarcis hispanica) by administering [3H]-thymidine and bromodeoxyuridine as proliferation markers and euthanizing the animals at different survival times to determine the identity of progenitor cells and to study their lineage derivatives. After short survival times, only type B cells are labeled, suggesting that they are neural stem cells. Three days after administration, some type A cells are labeled, corresponding to recently formed neuroblasts. Type A cells migrate to their final destinations, where they differentiate into mature neurons and integrate into functional circuits. Our results after long survival periods suggest that, in addition to actively dividing type B cells, there is also a type B subpopulation with low proliferative activity. We also found that new neurons incorporated into the olfactory bulb are generated both in situ, in the walls of the anterior extension of the lateral ventricle of the olfactory bulbs, but also at more caudal levels, most likely in anterior levels of the sulcus ventralis/terminalis. These cells follow a tangential migration toward the olfactory bulbs where they integrate. We hypothesized that at least part of the newly generated neurons would undergo a specialization process over time. In support of this prediction, we found two neuronal populations in the cellular layer of the medial cortex, which we named type I and II neurons. At intermediate survival times (1 month) only type II neurons were labeled with [3H]-thymidine, while at longer survival times (3, 6, or 12 months) both type I and type II neurons were labeled. This study sheds light on the ultrastructural characteristics of the ventricular zone of P. liolepis as a neurogenic niche, and adds to our knowledge of the processes whereby newly generated neurons in the adult brain migrate and integrate into their final destinations

Membrane-to-Nucleus Signaling in Human Blood Progenitor Cells Reveals an Efficient GM-Free Reprogramming to Pluripotency

The generation of induced pluripotent stem cells (iPSCs) by forced expression of defined transcription factors has revolutionized regenerative medicine. These cells have similar features to embryonic stem cells (ESCs) regarding self-renewal and their ability to differentiate into any cell type in the body. In spite of many improvements, in using nonviral delivery reprogramming methods, there are still challenges to overcome regarding safety before patient-made iPSCs can be used in regular clinical practice. We have recently reported about a gene manipulation-free method of generating human pluripotent stem cells (PSCs), based on activation of the novel human GPI-linked glycoprotein ACA. The process of dedifferentiation of blood progenitor cells that leads to the generation of blood-derived pluripotent stem cells (BD-PSCs) is initiated upon cross-linking of this protein via activation of PLCγ/PI3K/Akt pathway. These cells are mortal, express pluripotent markers, and redifferentiate in vitro into cells of all three germ layers. The ultrastructural analysis of BD-PSCs, by means of electron microscopy, revealed them similar to human ESCs with large dense nucleolus and scarce cytoplasm. BD-PSCs are autologous stem cells and while nonteratogenic offer a new alternative that overcomes immunological, ethical, and safety concerns and opens up a new avenue in treating contemporarily intractable diseases and generally in human therapeutics