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Hippocampus development and generation of dentate gyrus granule cells irregulate by LEF1
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Lef1 and other genes of the LEF1/TCF family of transcription factors are nuclear mediators of Wnt signaling. Here we examine the expression pattern and functional importance of Lef1 in the developing forebrain of the mouse. Lef1 is expressed in the developing hippocampus, and LEF1-deficient embryos lack dentate gyrus granule cells but contain glial cells and interneurons in the region of the dentate gyrus. In mouse embryos homozygous for a Lef1-lacZ fusion gene, which encodes a protein that is not only deficient in DNA binding but also interferes with (beta)-catenin-mediated transcriptional activation by other LEF1/TCF proteins, the entire hippocampus including the CA fields is missing. Thus, LEF1 regulates the generation of dentate gyrus granule cells, and together with other LEF1/TCF proteins, the development of the hippocampus.
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... It has been demonstrated that both extrinsic signals, such as WNTs and BMPs, and intrinsic factors, including EMX1, EMX2, LEF1, LHX2, and LHX5, are involved in the regulation of early morphogenesis of the hippocampus. As the earliest Wnt gene to be exclusively expressed in the cortical hem, Wnt3a is required for the genesis of the hippocampus (Lee et al., 2000); in addition, Lef1 is downstream of Wnt signaling, and the hippocampus is completely absent in Lef1 neo/neo null mutant mice (Galceran et al., 2000). Wnt signaling is essential for early development of the hippocampus. ...
... Then, we mainly focused on the intrinsic regulatory networks by analyzing the expression profiles of two groups of transcription factor genes. The Foxg1, Gli3, Lhx2, Otx1, Otx2, and Pax6 genes, which are highly related to the early patterning of the dorsal telencephalon (Hébert and Fishell, 2008), were in the first group; Axin2, Emx1, Emx2, Lef1, Lhx5, and Tcf4 genes, which are associated with early hippocampal development (Galceran et al., 2000;Moore and Iulianella, 2021;Tole et al., 2000;Yoshida et al., 1997;Zhao et al., 1999), were in the other group. The expression of the Foxg1, Gli3, Lhx2, Otx1, Otx2, and Pax6 genes was comparable between the controls and double mutants ( Figure 5A), indicating that the early patterning of the dorsal telencephalon is largely unaltered. ...
... It is known that both extrinsic signals and intrinsic factors participate in the regulation of the early development of the hippocampus. Notably, mutations of Wnt3a and Lef1 eliminate the entire hippocampus (Galceran et al., 2000;Lee et al., 2000). Given that the expression of Axin2, Lef1, and Tcf4, three Wnt-responsive transcription factor genes, was not altered in the Nr2f double mutant ( Figure 5A), it is unlikely that abnormal Wnt signaling is the cause of the compromised hippocampus. ...
The hippocampus executes crucial functions from declarative memory to adaptive behaviors associated with cognition and emotion. However, the mechanisms of how morphogenesis and functions along the hippocampal dorsoventral axis are differentiated and integrated are still largely unclear. Here, we show that Nr2f1 and Nr2f2 genes are distinctively expressed in the dorsal and ventral hippocampus, respectively. The loss of Nr2f2 results in ectopic CA1/CA3 domains in the ventral hippocampus. The deficiency of Nr2f1 leads to the failed specification of dorsal CA1, among which there are place cells. The deletion of both Nr2f genes causes almost agenesis of the hippocampus with abnormalities of trisynaptic circuit and adult neurogenesis. Moreover, Nr2f1/2 may cooperate to guarantee appropriate morphogenesis and function of the hippocampus by regulating the Lhx5-Lhx2 axis. Our findings revealed a novel mechanism that Nr2f1 and Nr2f2 converge to govern the differentiation and integration of distinct characteristics of the hippocampus in mice.
... In situ hybridization verified that the expression of Lef1, the gene encoding the transcriptional co-factor of β-Catenin to activate Wnt signaling, is significantly upregulated in E16.5 cKO hippocampi ( Fig. 5j-l). LEF1 not only has an early role in specifying the hippocampus, but also controls the generation of dentate gyrus granule cells 37 . Similarly, the expression of Sfrp2, another Wnt signaling pathway component was greatly enhanced in E16.5 cKO hippocampi and VZ/SVZ of neocortices ( Fig. 5m-o). ...
... Wnt signaling governs multiple aspects of neural development including neurulation, pattern formation, and fate choices of neural progenitors [60][61][62] . Moreover, the strength and gradient of the canonical Wnt signaling in the RGC-IPCneuron path and through developmental time ensures proper cell fate establishment and transition [63][64][65] , including those in hippocampal morphogenesis 4,37 . Deletion of KDM2B-CxxC greatly elevated Wnt signaling in hippocampi of multiple developing stages and in hippocampal progenitors, which could lead to impeded migration and differentiation of IPCs. ...
The hippocampus plays major roles in learning and memory, and its formation requires precise coordination of patterning, cell proliferation, differentiation, and migration. Here we removed the chromatin-association capability of KDM2B in the progenitors of developing dorsal telencephalon ( Kdm2b ∆CxxC ) to discover that Kdm2b ∆CxxC hippocampus, particularly the dentate gyrus, became drastically smaller with disorganized cellular components and structure. Kdm2b ∆CxxC mice display prominent defects in spatial memory, motor learning and fear conditioning, resembling patients with KDM2B mutations. The migration and differentiation of neural progenitor cells is greatly impeded in the developing Kdm2b ∆CxxC hippocampus. Mechanism studies reveal that Wnt signaling genes in developing Kdm2b ∆CxxC hippocampi are de-repressed due to reduced enrichment of repressive histone marks by polycomb repressive complexes. Activating the Wnt signaling disturbs hippocampal neurogenesis, recapitulating the effect of KDM2B loss. Together, we unveil a previously unappreciated gene repressive program mediated by KDM2B that controls progressive fate specifications and cell migration, hence morphogenesis of the hippocampus.
... Downstream of Pax6 is Neurog2, which regulates Neurod1 expression. Neurog2 and Neurod1 heterodimerize to control progenitor cell production and the amplification of granule neuron progenitors, and the generation of the granule neurons of the hippocampus, which is dependent on Neurod1 and lymphoid-enhancer-binding protein 1 (Lef1 [50][51][52][53]). How many interneurons and primary pyramidal neurons develop remains unclear beyond the reduction of granule cells in Neurod1 null mice. ...
... The dentate gyrus of the hippocampus is one of the brain areas where neural stem cells persist during adulthood in most mammals [101]. Granule cells of the hippocampus depend on Wnt/β-catenin, Dkk, Neurod1, and Lef1, which will not develop if Neurod1 and Lef1 are deleted [35,37,51,53]. Labeling the newly formed granule neurons in the dentate gyrus showed that the maturation of adult-generated granule cells was slower than neonatal-generated granule cells [101][102][103]. ...
The development of the central auditory system, including the auditory cortex and other areas involved in processing sound, is shaped by genetic and environmental factors, enabling infants to learn how to speak. Before explaining hearing in humans, a short overview of auditory dysfunction is provided. Environmental factors such as exposure to sound and language can impact the development and function of the auditory system sound processing, including discerning in speech perception, singing, and language processing. Infants can hear before birth, and sound exposure sculpts their developing auditory system structure and functions. Exposing infants to singing and speaking can support their auditory and language development. In aging humans, the hippocampus and auditory nuclear centers are affected by neurodegenerative diseases such as Alzheimer’s, resulting in memory and auditory processing difficulties. As the disease progresses, overt auditory nuclear center damage occurs, leading to problems in processing auditory information. In conclusion, combined memory and auditory processing difficulties significantly impact people’s ability to communicate and engage with their societal essence.
... When Wnt3a is knocked out and Wnt signaling is lost, the mouse hippocampus does not develop normally [32,33]. Furthermore, the hippocampus develops poorly in LEF1-knockout mice, a transcription factor known as a target gene for Wnt/β-catenin signaling [34]. BMPs are secreted from the lateral edges and dorsal midline of the neural plate. ...
The telencephalon is the largest region of the brain and processes critical brain activity. Despite much progress, our understanding of the telencephalon’s function, development, and pathophysiological processes remains largely incomplete. Recently, 3-dimensional brain models, known as brain organoids, have attracted considerable attention in modern neurobiological research. Brain organoids have been proven to be valuable for studying the neurodevelopmental principles and pathophysiology of the brain, as well as for developing potential therapeutics. Brain organoids can change the paradigm of current research, replacing animal models. However, there are still limitations, and efforts are needed to improve brain organoid models. In this review, we provide an overview of the development and function of the telencephalon, as well as the techniques and scientific methods used to create fully developed telencephalon organoids. Additionally, we explore the limitations and challenges of current brain organoids and potential future advancements.
... 14 The deficiency of Lef1 leads to reduced granule cells perinatally, thereby leading to deprive the entire DG development during in postnatal brain. 15,16 Fate-mapping analysis using Axin2-CreER T2 mice demonstrates that embryonic dentate neural progenitors are Wnt responsive at early gestation (embryonic day 11.5 [E11.5]) before they populate their progeny and surrounding niche in adult DG. 17 Moreover, adult NSCs are still responsive to Wnt morphogens throughout adulthood. ...
Neural stem cells (NSCs) in the adult hippocampus are composed of multiple subpopulations. However, their origin and functional heterogeneity are still unclear. Here, we found that the contribution of murine Wnt-responsive (Axin2+) and Hedgehog-responsive (Gli1+) embryonic neural progenitors to adult NSCs started from early and late postnatal stages, respectively. Axin2+ adult NSCs were intended to actively proliferate, whereas Gli1+ adult NSCs were relatively quiescent and responsive to external stimuli. Moreover, Gli1+ NSC-derived adult-born neurons exhibited more complex dendritic arborization and connectivity than Axin2+ NSC-derived ones. Importantly, genetic cell ablation analysis identified that Axin2+ and Gli1+ adult NSCs were involved in hippocampus-dependent learning, but only Axin2+ adult NSCs were engaged in buffering stress responses and depressive behavior. Together, our study not only defined the heterogeneous multiple origins of adult NSCs but also advanced the concept that different subpopulations of adult NSCs may function differently.
In mouse dentate gyrus, radial glia-like cells (RGLs) persist throughout life and play a critical role in the generation of granule neurons. A large body of evidence has shown that the combinatorial expression of transcription factors (TFs) defines cell types in the developing central nervous system (CNS). As yet, the identification of specific TFs that exclusively define RGLs in the developing mouse dentate gyrus (DG) remains elusive. Here we show that phospho-Smad3 (PSmad3) is expressed in a subpopulation of neural progenitors in the DG. During embryonic stage (E14-15), PSmad3 was predominantly expressed in gfap-GFP-positive (GFP+)/Sox2+ progenitors located at the lower dentate notch (LDN). As the development proceeds (E16-17), the vast majority of PSmad3+ cells were GFP+/Sox2+/Prox1low+/Ki67+ proliferative progenitors that eventually differentiated into granule neurons. During postnatal stage (P1–P6) PSmad3 expression was observed in GFP+ progenitors and astrocytes. Subsequently, at P14–P60, PSmad3 expression was found both in GFP⁺ RGLs in the subgranular zone (SGZ) and astrocytes in the molecular layer (ML) and hilus. Notably, PSmad3+ SGZ cells did not express proliferation markers such as PCNA and phospho-vimentin, suggesting that they are predominantly quiescent from P14 onwards. Significantly PSmad3+/GFP+ astrocytes, but not SGZ cells, co-expressed Olig2 and S100β. Together, PSmad3+/Olig2− expression serves as an exclusive marker for a specific subpopulation of GFP+ neural progenitors and RGLs in the mouse DG during both embryonic and postnatal period.
Development of the mammalian telencephalon, which is the most complex region of the central nervous system, is precisely orchestrated by many signaling molecules. Wnt signaling derived from the cortical hem, a signaling center, is crucial for telencephalic development including cortical patterning and the induction of hippocampal development. Secreted protein R-spondin (Rspo) 1-4 and their receptors, leucine-rich repeat-containing G-protein-coupled receptor (Lgr) 4-6, act as activators of Wnt signaling. Although Rspo expression in the hem during the early stages of cortical development has been reported, comparative expression analysis of Rspos and Lgr4-6 has not been performed. In this study, we examined the detailed spatiotemporal expression patterns of Rspo1-4 and Lgr4-6 in the embryonic and postnatal telencephalon to elucidate their functions. In the embryonic day (E) 10.5-14.5 telencephalon, Rspo1-3 were prominently expressed in the cortical hem. Among their receptors, Lgr4 was observed in the ventral telencephalon, and Lgr6 was highly expressed throughout the telencephalon at the same stages. This suggests that Rspo1-3 and Lgr4 initially regulate telencephalic development in restricted regions, whereas Lgr6 functions broadly. From the late embryonic stage, the expression areas of Rspo1-3 and Lgr4-6 dramatically expanded; their expression was found in the neocortex and limbic system, such as the hippocampus, amygdala, and striatum. Increased Rspo and Lgr expression from the late embryonic stages suggests broad roles of Rspo signaling in telencephalic development. Furthermore, the Lgr+ regions were located far from the Rspo+ regions, especially in the E10.5-14.5 ventral telencephalon, suggesting that Lgrs act via a Rspo-independent pathway.
Targeted inactivation of the murine gene encoding the transcription factor LEF-1 abrogates the formation of organs that depend on epithelial-mesenchymal tissue interactions. In this study we have recombined epithelial and mesenchymal tissues from normal and LEF-1-deficient embryos at different stages of development to define the LEF-1-dependent steps in tooth and whisker organogenesis. At the initiation of organ development, formation of the epithelial primordium of the whisker but not tooth is dependent on mesenchymal Lef1 gene expression. Subsequent formation of a whisker and tooth mesenchymal papilla and completion of organogenesis require transient expression of Lef1 in the epithelium. These experiments indicate that the effect of Lef1 expression is transmitted from one tissue to the other. In addition, the finding that the expression of Lef1 can be activated by bone morphogenetic protein 4 (BMP-4) suggests a regulatory role of this transcription factor in BMP-mediated inductive tissue interactions.
A LIM homeobox gene, Lim5, is known to be expressed in the forebrain of Xenopus and zebrafish (Toyama et al. [1995] Dev. Biol. 170:583–593). Results from developmental and comparative studies of its mouse ortholog, Lhx5, indicate that this gene may play important roles in forebrain development. Lhx5 expression is detected in the most anterior portion of the neural tube at the headfold stage, overlapping partially with Otx2 expression domain. After neural tube closure, Lhx5 is expressed as a transverse stripe, covering most of the diencephalic primordium. This expression recedes to restricted areas as Dlx gene expression occurs. By midgestation, both genes, Lhx5 and Dlx5, are expressed in the diencephalon and ventral telencephalon in an alternating complementary pattern. It may be that Dlx inhibits Lhx5, and this may represent a step of early regionalization of the forebrain. Lhx5 is also expressed in midbrain, hindbrain, and spinal cord, overlapping extensively with Lhx1 starting from day E10.5 of gestation. The early, persistent, and dynamic expression of Lhx5 suggests a regulatory function in forebrain formation. Dev. Dyn. 208:266–277, 1997. © Wiley-Liss, Inc.†
The Wnt pathway regulates the early dorsal-ventral axis in Xenopus through a complex of beta-catenin and HMG box transcription factors of the Lef/Tcf family. We show that the promoter of the dorsalizing homeo box gene siamois is a direct target for the beta-catenin/XTcf-3 complex, establishing a link between the Wnt pathway and the activation of genes involved in specifying the dorsal axis. By injecting siamois reporter constructs into the animal pole of Xenopus embryos, we show that a 0.8-kb fragment of the siamois promoter is strongly activated by beta-catenin. The proximal 0.5 kb, which is also activated by beta-catenin, contains three Lef/Tcf-binding sites. Mutations in these sites eliminate the beta-catenin-mediated activation of siamois and show that siamois is regulated by the beta-catenin/XTcf-3 complex, in combination with additional transcriptional activators. When expressed at the equator of the embryo, the siamois promoter is activated to much higher levels on the dorsal side than the ventral side. Ectopic ventral expression of beta-catenin raises the ventral expression of the siamois promoter to the dorsal levels. Conversely, ectopic dorsal expression of dominant-negative XTcf-3 abolishes the dorsal activation of the siamois promoter. Furthermore, elimination of the Lef/Tcf sites elevates the ventral expression of siamois, revealing a repressive role for XTcf-3 in the absence of beta-catenin. Finally, we find that the endogenous siamois activator, although present throughout the dorsal side of the embryo, is most potent in the dorsal vegetal region. We propose that the dorsal activation of siamois by the beta-catenin/XTcf-3 complex combined with the ventral repression of siamois by XTcf-3 results in the restriction of endogenous siamois expression to the dorsal side of Xenopus embryos.
Brain factor-1 (BF-1) is a winged-helix (WH) transcription factor with a restricted pattern of expression in the neural tube. In the embryo, BF-1 is localized to the progenitor cells of the most rostral neural tube, the telencephalic neuroepithelium. Expression of BF-1 persists in the adult brain in the structures derived from the telencephalon, including the cerebral cortex, the hippocampus, the olfactory bulbs and the basal ganglia. Targeted disruption of the BF-1 gene in mice results in hypoplasia of the cerebral hemispheres. Proliferation of the telencephalic neuroepithelium is decreased and neuronal differentiation occurs prematurely. The forebrain of the BF-1 (‐/‐) mutant also displays dorsal‐ventral patterning defects. Development of the ventral (basal) region of the telencephalon is more severely affected than the dorsal region. These anomalies are associated with the ectopic expression of BMP4 in the dorsal telencephalic neuroepithelium and the loss of shh in the ventral telencephalon. These results raise the possibility that BF-1 may modulate both progenitor cell proliferation and regional patterning by regulating the expression or activity of inductive signals which act on the telencephalic neuroepithelium.
Using a functional screen in Xenopus embryos, we identified a novel function for the HMG box protein XSox17β. Ectopic expression of XSox17β ventralizes embryos by inhibiting the Wnt pathway downstream of β-catenin but upstream of the Wnt-responsive gene Siamois. XSox17β also represses transactivation of a TCF/LEF-dependent reporter construct by Wnt and β-catenin. In animal cap experiments, it both activates transcription of endodermal genes and represses β-catenin-stimulated expression of dorsal genes. The inhibition activity of XSox17β maps to a region C-terminal to the HMG box; this region of XSox17β physically interacts with the Armadillo repeats of β-catenin. Two additional Sox proteins, XSox17α and XSox3, likewise bind to β-catenin and inhibit its TCF-mediated signaling activity. These results reveal an unexpected mechanism by which Sox proteins can modulate Wnt signaling pathways.
CD3-epsilon expression is controlled by a downstream T lymphocyte-specific enhancer element. We report the identification of a T cell-specific transcription factor, TCF-1, binding to this element. The multimerized recognition motif of TCF-1 constituted a T cell-specific enhancer. Subsequent cloning of TCF-1 identified three splice alternatives. TCF-1 contained a single DNA-binding HMG box most closely related to similar boxes in the putative mammalian sex-determining gene SRY and in the Schizosaccharomyces pombe Mc mating type gene. TCF-1 mRNA was expressed uniquely in T lymphocytes. Upon cotransfection into non-T cells, TCF-1 could transactivate through its cognate motif. These results identify TCF-1 as a T cell-specific transcription factor, which might play a role in the establishment of the mature T cell phenotype.
The mammalian hippocampus contains the neural circuitry that is crucial for cognitive functions such as learning and memory.
The development of such circuitry is dependent on the generation and correct placement of the appropriate number and types
of neurons. Mice lacking function of the LIM homeobox gene Lhx5 showed a defect in hippocampus development. Hippocampal neural precursor cells were specified and proliferated, but many
of them failed to either exit the cell cycle or to differentiate and migrate properly.Lhx5 is therefore essential for the regulation of precursor cell proliferation and the control of neuronal differentiation and
migration during hippocampal development.
Interactions between cells help to elaborate pattern within the vertebrate central nervous system (CNS)1. The genes Wnt-1 and Wnt-3a, which encode members of the Wnt family of cysteine-rich secreted signals, are coexpressed at the dorsal midline of the developing neural tube, coincident with dorsal patterning2, 3. Each signal is essential for embryonic development, Wnt-1 for midbrain patterning4, 5 and Wnt-3a for formation of the paraxial mesoderm6, but the absence of a dorsal neural-tube phenotype in each mutant suggests that Wnt signalling may be redundant. Here we demonstrate that in the absence of both Wnt-1 and Wnt-3a there is a marked deficiency in neural crest derivatives, which originate from the dorsal neural tube7, and a pronounced reduction in dorsolateral neural precursors within the neural tube itself. These phenotypes do not seem to result from a disruption in the mechanisms responsible for establishing normal dorsoventral polarity. Rather, our results are consistent with a model in which local Wnt signalling regulates the expansion of dorsal neural precursors. Given the widespread expression of different Wnt genes in discrete areas of the mammalian neural tube3, this may represent a general model for the action of Wnt signalling in the developing CNS.
This study deals with the site of origin, migration, and settling of the principal cell constituents of the rat hippocampus during the embryonic period, The results indicate that the hippocampal neuroepithelium consists of three morphogenetically discrete components—the Ammonic neuroepithelium, the primary dentate neuroepithelium, and the fimbrial glioepithelium—and that these are discrete sources of the large neurons of Ammon's horn, the smaller granular neurons of the dentate gyrus, and the glial cells of the fimbria.
The putative Ammonic neuroepithelium is marked in short‐survival thymidine radiograms by a high level of proliferative activity and evidence of interkinetic nuclear migration from day E16 until day E19. On days E16 and E17 a diffuse band of unlabeled cells forms outside the Ammonic neuroepithelium. These postmitotic cells are considered to be stratum radiatum and stratum oriens neurons, which are produced in large numbers as early as day E15. A cell‐dense layer, the incipient stratum pyramidale, begins to form on day E18 and spindle‐shaped cells can be traced to it from the Ammonic neuroepithelium. This migratory band increases in size for several days, then declines, and finally disappears by day E22. It is inferred that this migration contains the pyramidal cells of Ammon's horn that are produced mostly on days E17 through E20.
The putative primary dentate neuroepithelium is distinguished from the Ammonic neuroepithelium during the early phases of embryonic development by its location, shape, and cellular dynamics. It is located around a ventricular indentation, the dentate notch, contains fewer mitotic cells near the lumen of the ventricle than the Ammonic neuroepithelium, and shows a different labeling pattern both in short‐survival and sequential‐survival thymidine radiograms. By day E18, the reduced primary dentate neuroepithelium is surrounded by an aggregate of proliferative cells; this is the secondary dentate matrix. On the subsequent days spindle‐shaped cells that have retained their proliferative capacity migrate from the progressively receding secondary dentate matrix to the dentate gyrus itself. The latter, representing a tertiary germinal matrix, becomes highly active during the perinatal period.
The putative fimbrial glioepithelium is situated between the primary dentate neuroepithelium and the tip of the hippocampal rudiment. Observations in methacrylate sections and thymidine radiograms suggest that the cells of this germinal matrix, unlike typical neuroepithelial cells, do not undergo interkinetic nuclear migration. The fimbrial glioepithelium is clearly present by day E16, two days before the fimbria becomes a distinct fiber tract. As the fimbria emerges, cells of the putative glial matrix migrate into it.