L3/Lhx8 is a pivotal factor for cholinergic differentiation of murine embryonic stem cells

Mispatterning and interneuron deficit in Tourette Syndrome basal ganglia organoids

Tourette Syndrome (TS) is a neuropsychiatric disorder thought to involve a reduction of basal ganglia (BG) interneurons and malfunctioning of the BG circuitry. However, whether interneurons fail to develop or are lost postnatally remains unknown. To investigate the pathophysiology of early development in TS, induced pluripotent stem cell (iPSC)-derived BG organoids from TS patients and healthy controls were compared on multiple levels of measurement and analysis. BG organoids from TS individuals manifested an impaired medial ganglionic eminence fate and a decreased differentiation of cholinergic and GABAergic interneurons. Transcriptome analyses revealed organoid mispatterning in TS, with a preference for dorsolateral at the expense of ventromedial fates. Our results point to altered expression of GLI transcription factors downstream of the Sonic Hedgehog signaling pathway with cilia disruption at the earliest stages of BG organoid differentiation as a potential mechanism for the BG mispatterning in TS. This study uncovers early neurodevelopmental underpinnings of TS neuropathological deficits using organoids as a model system.

Genetic Regulation of Vertebrate Forebrain Development by Homeobox Genes

Forebrain development in vertebrates is regulated by transcription factors encoded by homeobox, bHLH and forkhead gene families throughout the progressive and overlapping stages of neural induction and patterning, regional specification and generation of neurons and glia from central nervous system (CNS) progenitor cells. Moreover, cell fate decisions, differentiation and migration of these committed CNS progenitors are controlled by the gene regulatory networks that are regulated by various homeodomain-containing transcription factors, including but not limited to those of the Pax (paired), Nkx, Otx (orthodenticle), Gsx/Gsh (genetic screened), and Dlx (distal-less) homeobox gene families. This comprehensive review outlines the integral role of key homeobox transcription factors and their target genes on forebrain development, focused primarily on the telencephalon. Furthermore, links of these transcription factors to human diseases, such as neurodevelopmental disorders and brain tumors are provided.

Maternal high sugar and fat diet benefits offspring brain function via targeting on the gut-brain axis

A recent study showed that a gestational high fat diet protects 3xTg-AD offspring from memory impairments, synaptic dysfunction, and brain pathology. However, it is unknown whether this diet exerts the same effects on normal mice or on other functions, and if so, how. In the present study, mother mice were pre-fed a high sugar and high fat (HSHF) diet for 1 month and then fertilized; the HSHF diet was continued until birth and then mother mice were returned to a standard diet. The gut microbiota, and intestinal and brain functions of the offspring were dynamically monitored at 7, 14, 28, and 56 days old until 16 months of age. Results showed that the HSHF diet significantly affected the gut microbiota structure of the offspring, especially during the early life stage. In addition, in the HSHF diet offspring, there were influenced on various types of neurons, including cholinergic and GABAergic neurons, on autophagy levels in the brain, and on inflammation levels in the intestinal tract. When the offspring grew older (16 months), we found that some genes of benefit against nervous system disease were activated, such as Lhx8, GPR88, RGS9, CD4, DRD2, RXRG, and Syt6, and the expression of cholinergic and GABAergic neurons biomarker protein increased. Although the inflammation levels in the nervous and peripheral systems showed no obvious differences, the AFP level of individuals on the HSHF diet was much higher than those on the standard diet, suggesting that more accurate and/or personalized nutrition is needed. Taken together, the results show that a maternal HSHF diet benefits the offspring by reducing the risk of nervous diseases, which might depend on LHX8 activation to modulate cholinergic and GABAergic neurons via the gut–brain axis, but still need much more deep studies.

Aging-relevant human basal forebrain cholinergic neurons as a cell model for Alzheimer's disease

Background

Alzheimer’s disease (AD) is an adult-onset mental disorder with aging as a major risk factor. Early and progressive degeneration of basal forebrain cholinergic neurons (BFCNs) contributes substantially to cognitive impairments of AD. An aging-relevant cell model of BFCNs will critically help understand AD and identify potential therapeutics. Recent studies demonstrate that induced neurons directly reprogrammed from adult human skin fibroblasts retain aging-associated features. However, human induced BFCNs (hiBFCNs) have yet to be achieved.

Methods

We examined a reprogramming procedure for the generation of aging-relevant hiBFCNs through virus-mediated expression of fate-determining transcription factors. Skin fibroblasts were obtained from healthy young persons, healthy adults and sporadic AD patients. Properties of the induced neurons were examined by immunocytochemistry, qRT-PCR, western blotting, and electrophysiology.

Results

We established a protocol for efficient generation of hiBFCNs from adult human skin fibroblasts. They show electrophysiological properties of mature neurons and express BFCN-specific markers, such as CHAT, p75NTR, ISL1, and VACHT. As a proof-of-concept, our preliminary results further reveal that hiBFCNs from sporadic AD patients exhibit time-dependent TAU hyperphosphorylation in the soma and dysfunctional nucleocytoplasmic transport activities.

Conclusions

Aging-relevant BFCNs can be directly reprogrammed from human skin fibroblasts of healthy adults and sporadic AD patients. They show promises as an aging-relevant cell model for understanding AD pathology and may be employed for therapeutics identification for AD.

RP1, a RAGE antagonist peptide, can improve memory impairment and reduce Aβ plaque load in the APP/PS1 mouse model of Alzheimer's disease

Amyloid-β (Aβ) accumulation is a pathological hallmark of Alzheimer's disease (AD). The receptor for advanced glycation end products (RAGE) is involved in the production and accumulation of Aβ. RP1, a peptide antagonist of RAGE, was screened by phage display technology in our previous studies, and its neuroprotective effects on an AD cell model have been confirmed. However, its efficacy in vivo remains unclear. Here, the intranasal delivery of RP1 to APPSwe/PS1dE9 (APP/PS1) mice significantly improved memory impairment and relieved the Aβ burden by decreasing the expression of amyloid precursor protein and β-secretase. RNA-sequencing (RNA-seq) was utilized to identify differentially expressed genes (DEGs) in APP/PS1 mice after RP1 administration. Several DEGs in RAGE downstream signalling pathways were downregulated. Some transcription factors (such as Fos) and the pathways enriched in the remarkable modules may also be related to the efficacy of RP1. In conclusion, RP1 significantly improves the AD symptoms of APP/PS1 mice, and the RNA-seq results provide new ideas for elucidating the possible mechanisms of RP1 treatment.

GAS5 which is regulated by Lhx8 promotes the recovery of learning and memory in rats with cholinergic nerve injury

Damage to the cholinergic system in central nervous system injuries such as traumatic brain injury (TBI) and neurodegenerative diseases leads to impaired learning and cognition. Neural stem cells (NSCs) have self-renewal capacity and multi-directional differentiation potential and considered the best source of cells for cell replacement therapy. However, how to promote the differentiation of NSCs into neurons is a major challenge in current research. Lhx8 has a specific effect on the development of the cholinergic nervous system, but its exact function is unclear. In this study, we found that Lhx8 could regulate the expression of Growth arrest-specific (GAS)5 which has been implicated in cancer but was less studied in the nervous system. Additionally, results from PCR, fluorescence in situ hybridization, and immunocytochemical analyses showed that GAS5 is mainly expressed in the cytoplasm of hippocampal neural stems cells and promotes their differentiation into neurons; the Morris water maze test demonstrated that GAS5 overexpression restored learning and memory in rats with cholinergic injury. These findings indicate that GAS5, which is regulated by Lhx8, improve brain function following cholinergic nerve injury.

Long non-coding RNA GAS5 promotes PC12 cells differentiation into Tuj1-positive neuron-like cells and induces cell cycle arrest

Growth arrest-specific 5 (GAS5) is an anti-oncogene that has been extensively studied in tumors. However, research on GAS5 in the context of nervous system disease is rare at present. This study aimed to investigate the role of the long non-coding RNA GAS5 in rat pheochromocytoma cells (PC12 cells). GAS5-overexpressing lentivirus was transfected into PC12 cells, and expression levels of GAS5 and C-myc were detected by real-time PCR. Ratios of cells in S phase were detected by 5-ethynyl-2′-deoxyuridine. Immunohistochemical staining was used to detect the immunoreactivity of neuron microtubule markers Tuj1, doublecortin, and microtubule-associated protein 2. Apoptosis was detected by flow cytometry, while expression of acetylcholine in cells was detected by western blot assay. We found that GAS5 can promote PC12 cells to differentiate into Tuj1-positive neuron-like cells with longer processes. In addition, cell proliferation and cell cycle were significantly suppressed by GAS5, whereas it had no effect on apoptosis of PC12 cells. Our results indicate that GAS5 could increase the expression of choline acetyltransferase and acetylcholine release. Thus, we speculate that GAS5 is beneficial to the recovery of neurons and the cholinergic nervous system.

Regulation and/or Repression of Cholinergic Differentiation of Murine Embryonic Stem Cells Using RNAi Directed Against Transcription Factor L3/Lhx8

Techniques for controlling the expression of a specific gene in embryonic stem cells are effective and important for clarifying the functions of the gene. Regarding differentiation of cells into nervous system components, these techniques would play key roles in elucidating, not only the differentiation mechanisms of neuronal and glial cells but also how neuronal phenotypes are determined. In this chapter, we describe a RNA interference method for suppressing cholinergic differentiation in murine embryonic stem cells by knockdown of expression of the transcription factor L3/Lhx8, a Lim homeobox gene family protein. This method will greatly facilitate functional analyses of the factors involved in neuronal differentiation and regeneration and will contribute to cell transplantation studies.

Lhx6 and Lhx8: cell fate regulators and beyond

As transcription factors of the lines (LIN)-11/Islet (Isl)-1/mitosis entry checkpoint (MEC)-3 (LIM)-homeobox subfamily, LIM homeobox (Lhx)6 and -8 are remarkably conserved and involved in the morphogenesis of multiple organ systems. Lhx6 and -8 play overlapping and distinctive roles, but in general act as cell fate mediators and in turn are regulated by several transcriptional factors, such as sonic hedgehog, fibroblast growth factors, and wingless-int (Wnt)/β-catenin. In this review, we first summarize Lhx6 and -8 distributions in development and then explore how Lhx6 and -8 act as transcription factors and coregulators of cell lineage specification. Known Lhx6 and -8 functions and targets are outlined in neurogenesis, craniofacial development, and germ cell differentiation. The underlying mechanisms of Lhx6 and -8 in regulating cell fate remain elusive. Whether Lhx6 and -8 affect functions in tissues and organs other than neural, craniofacial, oocytes, and germ cells is largely unexplored. Taken together, Lhx6 and -8 are important regulators of cell lineage specification and may act as one of the pivotal mediators of stem cell fate. Undoubtedly, future investigations of Lhx6 and -8 biology will continue to yield fascinating insights into tissue development and homeostasis, in addition to their putative roles in tissue regeneration and ageing.

Retinoic acid as a therapeutic option in Alzheimer's disease: a focus on cholinergic restoration

Retinoic acid is a potent cell differentiating factor, which through its nuclear receptors affects a vast range of promoter sites in brain neuronal and glial cells in every step of embryonic and postnatal life. Its capacities, facilitating maturation of neurotransmitter phenotype in different groups of neurons, pave the way for its application as a potential therapeutic agent in neurodegenerative diseases including Alzheimer's disease. Retinoic acid was found to exert particularly strong enhancing effects on acetylcholine transmitter functions in brain cholinergic neurons, loss of which is tightly linked to the development of cognitive and memory deficits in course of different cholinergic encephalopathies. Here, we review cholinotrophic properties of retinoic acid and its derivatives, which may justify their application in the management of Alzheimer's disease and the related neurodegenerative conditions.

Overexpression of Lhx8 inhibits cell proliferation and induces cell cycle arrest in PC12 cell line

LIM-homeobox genes play a pivotal function in tissue patterning and differentiation, Lhx8 is a member of LIM-homeobox gene family, and it is selectively expressed in embryonic basal forebrain and is a key factor for the determination of cholinergic cells fate. However, besides cholinergic differentiation, little is known about the potential role of Lhx8 in cell biology. In this study, we transfected Lhx8 complementary DNA (cDNA) into PC12 cell line using lentiviral vectors to acquire the cells which stably expressed high level of Lhx8, and we provide the experimental evidence that overexpression of Lhx8 inhibits cell proliferation and induces cell cycle arrest but not apoptosis in vitro. In conclusion, besides cholinergic differentiation, our results suggest that Lhx8 also plays as a suppressor gene of proliferation in cell biology.

Upregulation of Lhx8 increase VAChT expression and ACh release in neuronal cell line SHSY5Y

Lhx8 is a transcription factor for cholinergic differentiation. Our previous experiments found upregulation of Lhx8 promoted cholinergic neuronal differentiation of hippocampal neural stem/progenitor cells or hippocampal newborn neurons in vitro. However, the role of Lhx8 in VAChT expression and ACh release is still less understood. In this report, we transfected Lhx8 cDNA into neuronal cell line SHSY5Y by lentiviral vectors to acquire the cells which stably expressed high level of Lhx8. Using this cell model, we provided experimental evidence that increasing Lhx8 upregulated the expression of ChAT and VAChT, and also increased the ACh release in culture medium. We suggested that Lhx8 overexpression is a useful strategy to increase the release of ACh and maybe of therapeutic value to neurodegenerative diseases.

LIM homeobox 8 (Lhx8) is a key regulator of the cholinergic neuronal function via a tropomyosin receptor kinase A (TrkA)-mediated positive feedback loop

Basal forebrain cholinergic neurons play an important role in cognitive functions such as learning and memory, and they are affected in several neurodegenerative diseases, including Alzheimer disease and Down syndrome. Despite their functional importance, the molecular mechanisms of functional maturation and maintenance of these cholinergic neurons after the differentiation stage have not been fully elucidated. This study demonstrates that the LIM homeobox 8 (Lhx8) transcription factor regulates cholinergic function in rat septal cholinergic neurons in primary cultures from E18.5 embryos and in the adult brain. Lhx8 expression modulated tropomyosin receptor kinase A (TrkA) expression in septal cholinergic neurons in vitro and in vivo, resulting in regulated acetylcholine release as an index of cholinergic function. In addition, Lhx8 expression and function were regulated by nerve growth factor (NGF), and the effect of NGF was potentiated by Lhx8-induced TrkA expression. Together, our findings suggest that positive feedback regulation between Lhx8, TrkA, and NGF is an important regulatory mechanism for cholinergic functions of the septum.

Dynamic expression of tyrosine hydroxylase mRNA and protein in neurons of the striatum and amygdala of mice, and experimental evidence of their multiple embryonic origin

Emotional and motivational dysfunctions observed in Parkinson's disease, schizophrenia, and drug addiction are associated to an alteration of the mesocortical and mesolimbic dopaminergic pathways, which include axons projecting to the prefrontal cortex, the ventral striatum, and the amygdala. Subpopulations of catecholaminergic neurons have been described in the cortex and striatum of several mammals, but the presence of such cells in the adult amygdala is unclear in murine rodents, and in other rodents appears to show variations depending on the species. Moreover, the embryonic origin of telencephalic tyrosine hydroxylase (TH) cells is unknown, which is essential for trying to understand aspects of their evolution, distribution and function. Herein we investigated the expression of TH mRNA and protein in cells of the striatum and amygdala of developing and adult mice, and analyzed the embryonic origin of such cells using in vitro migration assays. Our results showed the presence of TH mRNA and protein expressing cells in the striatum (including nucleus accumbens), central and medial extended amygdala during development, which are persistent in adulthood although they are less numerous, generally show weak mRNA expression, and some appear to lack the protein. Fate mapping analysis showed that these cells include at least two subpopulations with different embryonic origin in either the commissural preoptic area of the subpallium or the supraopto-paraventricular domain of the alar hypothalamus. These data are important for future studies trying to understand the role of catecholamines in modulation of emotion, motivation, and reward.

Lhx8 promote differentiation of hippocampal neural stem/progenitor cells into cholinergic neurons in vitro

Lhx8, also named L3, is a recently identified member of the LIM homeobox gene family. Previously, we found acetylcholinesterase (AChE)-positive cells in fimbria-fornix (FF) transected rat hippocampal subgranular zone (SGZ). In the present study, we detected choline acetyltransferase (ChAT)-positive cholinergic cells in hippocampal SGZ after FF transaction, and these ChAT-positive cells were double labeled by Lhx8. Then we overexpressed Lhx8 during neural differentiation of hippocampal neural stem/progenitor cells on adherent conditions using lentivirus Lenti6.3-Lhx8. The result indicated that overexpression of Lhx8 did not affect the proportion of MAP2-positive neurons, but increased the proportion of ChAT-positive cells in vitro. These results suggested that FF-transected hippocampal niche promoted the ChAT/Lhx8-positive cholinergic neurons generation in rodent hippocampus, and Lhx8 was not associated with the MAP2-positive neurons differentiation on adherent conditions, but played a role in the specification of cholinergic neurons derived from hippocampal neural stem/progenitor cells in vitro.

The avian subpallium: new insights into structural and functional subdivisions occupying the lateral subpallial wall and their embryological origins

The subpallial region of the avian telencephalon contains neural systems whose functions are critical to the survival of individual vertebrates and their species. The subpallial neural structures can be grouped into five major functional systems, namely the dorsal somatomotor basal ganglia; ventral viscerolimbic basal ganglia; subpallial extended amygdala including the central and medial extended amygdala and bed nuclei of the stria terminalis; basal telencephalic cholinergic and non-cholinergic corticopetal systems; and septum. The paper provides an overview of the major developmental, neuroanatomical and functional characteristics of the first four of these neural systems, all of which belong to the lateral telencephalic wall. The review particularly focuses on new findings that have emerged since the identity, extent and terminology for the regions were considered by the Avian Brain Nomenclature Forum. New terminology is introduced as appropriate based on the new findings. The paper also addresses regional similarities and differences between birds and mammals, and notes areas where gaps in knowledge occur for birds.

The controlled generation of functional basal forebrain cholinergic neurons from human embryonic stem cells

An early substantial loss of basal forebrain cholinergic neurons (BFCN) is a constant feature of Alzheimer's disease and is associated with deficits in spatial learning and memory. The ability to selectively control the differentiation of human embryonic stem cells (hESCs) into BFCN would be a significant step toward a cell replacement therapy. We demonstrate here a method for the derivation of a predominantly pure population of BFCN from hESC cells using diffusible ligands present in the forebrain at developmentally relevant time periods. Overexpression of two relevant human transcription factors in hESC-derived neural progenitors also generates BFCN. These neurons express only those markers characteristic of BFCN, generate action potentials, and form functional cholinergic synapses in murine hippocampal slice cultures. siRNA-mediated knockdown of the transcription factors blocks BFCN generation by the diffusible ligands, clearly demonstrating the factors both necessary and sufficient for the controlled derivation of this neuronal population. The ability to selectively control the differentiation of hESCs into BFCN is a significant step both for understanding mechanisms regulating BFCN lineage commitment and for the development of both cell transplant-mediated therapeutic interventions for Alzheimer's disease and high-throughput screening for agents that promote BFCN survival.

Regulation and/or repression of cholinergic differentiation of murine embryonic stem cells using RNAi directed against transcription factor L3/Lhx8

Techniques for controlling the expression of a specific gene in embryonic stem cells are effective and important for clarifying the functions of the gene. Regarding differentiation of cells into nervous system components, these techniques would play key roles in elucidating, not only the differentiation mechanisms of neuronal and glial cells, but also how neuronal phenotypes are determined. In this chapter, we describe an RNA interference method for suppressing cholinergic differentiation in murine embryonic stem cells by knockdown of expression of the transcription factor L3/Lhx8, a Lim homeobox gene family protein. This method will greatly facilitate functional analyses of the factors involved in neuronal differentiation and regeneration and contribute to cell transplantation studies.

Early evolution of the LIM homeobox gene family

Background

LIM homeobox (Lhx) transcription factors are unique to the animal lineage and have patterning roles during embryonic development in flies, nematodes and vertebrates, with a conserved role in specifying neuronal identity. Though genes of this family have been reported in a sponge and a cnidarian, the expression patterns and functions of the Lhx family during development in non-bilaterian phyla are not known.

Results

We identified Lhx genes in two cnidarians and a placozoan and report the expression of Lhx genes during embryonic development in Nematostella and the demosponge Amphimedon. Members of the six major LIM homeobox subfamilies are represented in the genomes of the starlet sea anemone, Nematostella vectensis, and the placozoan Trichoplax adhaerens. The hydrozoan cnidarian, Hydra magnipapillata, has retained four of the six Lhx subfamilies, but apparently lost two others. Only three subfamilies are represented in the haplosclerid demosponge Amphimedon queenslandica. A tandem cluster of three Lhx genes of different subfamilies and a gene containing two LIM domains in the genome of T. adhaerens (an animal without any neurons) indicates that Lhx subfamilies were generated by tandem duplication. This tandem cluster in Trichoplax is likely a remnant of the original chromosomal context in which Lhx subfamilies first appeared. Three of the six Trichoplax Lhx genes are expressed in animals in laboratory culture, as are all Lhx genes in Hydra. Expression patterns of Nematostella Lhx genes correlate with neural territories in larval and juvenile polyp stages. In the aneural demosponge, A. queenslandica, the three Lhx genes are expressed widely during development, including in cells that are associated with the larval photosensory ring.

Conclusions

The Lhx family expanded and diversified early in animal evolution, with all six subfamilies already diverged prior to the cnidarian-placozoan-bilaterian last common ancestor. In Nematostella, Lhx gene expression is correlated with neural territories in larval and juvenile polyp stages. This pattern is consistent with a possible role in patterning the Nematostella nervous system. We propose a scenario in which Lhx genes play a homologous role in neural patterning across eumetazoans.

Developmental aspects of the cholinergic system

Beyond its importance in sustaining or modulating different aspects of the activity of the central nervous system (CNS), the cholinergic system plays important roles during development. In the current review, we focus on the developmental aspects associated with major components of the cholinergic system: Acetylcholine, choline acetyltransferase, vesicular acetylcholine transporter, high-affinity choline transporter, acetylcholinesterase, nicotinic and muscarinic receptors. We describe when and where each one of these components is first identified in the CNS and the changes in their levels that occur during the course of prenatal and postnatal development. We also describe how these components are relevant to many events that occur during the development of the CNS, including progenitor cells proliferation and differentiation, neurogenesis, gliogenesis, neuronal maturation and plasticity, axonal pathfinding, regulation of gene expression and cell survival. It will be noticed that evidence regarding the developmental aspects of the cholinergic system comes mostly from studies that used agonists, such as nicotine, and antagonists, such as hemicholinium-3. Studies using immunohistochemistry and genetically altered mice also provided valuable information.

Stem cells in human neurodegenerative disorders--time for clinical translation?

Stem cell-based approaches have received much hype as potential treatments for neurodegenerative disorders. Indeed, transplantation of stem cells or their derivatives in animal models of neurodegenerative diseases can improve function by replacing the lost neurons and glial cells and by mediating remyelination, trophic actions, and modulation of inflammation. Endogenous neural stem cells are also potential therapeutic targets because they produce neurons and glial cells in response to injury and could be affected by the degenerative process. As we discuss here, however, significant hurdles remain before these findings can be responsibly translated to novel therapies. In particular, we need to better understand the mechanisms of action of stem cells after transplantation and learn how to control stem cell proliferation, survival, migration, and differentiation in the pathological environment.

Transforming growth factor-β3 expression up-regulates on cleft palates induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin in mice

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) has been shown to induce cleft palate, in which the molecular etiology of the defect is poorly characterized. Recently, transforming growth factor-β3 (TGF-β3) has been indicated to play an essential role in the development of palatal shelves. In this developmental toxicity study, we investigated the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on the expression of TGF-β3 in fetal mice. Pregnant C57BL/6 mice were exposed to corn oil or TCDD (32 μg/kg/day 64 μg/kg/day, per os) at embryonic day 10 (ED10), a drastic inhibition of palatal shelves was induced. By using RT-PCR (reverse transcription-polymerase chain reaction) and Western blot, the expressions of TGF-β3 was investigated. We found that the expression of TGF-β3 was gradually up-regulated in TCDD-treated group. These results suggest that cleft palate can be induced by TCDD exposure, the modification of TGF-β3 is related to its pathogenesis.

Embryonic stem cell-derived neural precursor grafts for treatment of temporal lobe epilepsy

Complex partial seizures arising from mesial temporal lobe structures are a defining feature of mesial temporal lobe epilepsy (TLE). For many TLE patients, there is an initial traumatic head injury that is the precipitating cause of epilepsy. Severe TLE can be associated with neuropathological changes, including hippocampal sclerosis, neurodegeneration in the dentate gyrus, and extensive reorganization of hippocampal circuits. Learning disabilities and psychiatric conditions may also occur in patients with severe TLE for whom conventional anti-epileptic drugs are ineffective. Novel treatments are needed to limit or repair neuronal damage, particularly to hippocampus and related limbic regions in severe TLE and to suppress temporal lobe seizures. A promising therapeutic strategy may be to restore inhibition of dentate gyrus granule neurons by means of cell grafts of embryonic stem cell-derived GABAergic neuron precursors. "Proof-of-concept" studies show that human and mouse embryonic stem cell-derived neural precursors can survive, migrate, and integrate into the brains of rodents in different experimental models of TLE. In addition, studies have shown that hippocampal grafts of cell lines engineered to release GABA or other anticonvulsant molecules can suppress seizures. Furthermore, transplants of fetal GABAergic progenitors from the mouse or human brain have also been shown to suppress the development of seizures. Here, we review these relevant studies and highlight areas of future research directed toward producing embryonic stem cell-derived GABAergic interneurons for cell-based therapies for treating TLE.

Enhanced co-expression of beta-tubulin III and choline acetyltransferase in neurons from mouse embryonic stem cells promoted by icaritin in an estrogen receptor-independent manner

A previous small molecule screen demonstrated that some prenylflavonoids can promote neuronal differentiation from mouse embryonic stem (ES) cells based on morphologic criteria. Here we build on this observation and examine the neuronal subtypes induced by icaritin, a compound screened, and the molecular events underlying the differentiation. In the presence of icaritin, the number of neural rosettes in embryoid bodies (EBs) expressing nestin efficiently increased and the neuroectodermal gene Fgf5 expression upregulated during germ layer formation. The neural progenitors generated from icaritin-treated EBs were further differentiated into the neurons (marked by beta-tubulin III) and also enhanced the choline acetyltransferase (ChAT) expression upon terminal differentiation. A suppression of p38 mitogen-activated protein kinase (p38MAPK) phosphorylation and sustained extracellular signal-regulated protein kinase (ERK) phosphorylation existed simultaneously without estrogen-like activities involved. Taken together, enhanced co-expression of beta-tubulin III and choline acetyltransferase in neuronal differentiation from mouse ES cells is promoted by icaritin via estrogen receptor-independent action.

Knockdown of the L3/Lhx8 gene suppresses cholinergic differentiation of murine embryonic stem cell-derived spheres

L3/Lhx8, a member of the Lim-homeobox gene family, is selectively and specifically expressed in the murine embryonic medial ganglionic eminence (MGE). Our previous study demonstrated that L3/Lhx8-deficient mice specifically lack cholinergic neurons in the basal forebrain. In this manuscript, we report the in vitro effects of reduced L3/Lhx8 gene expression on cholinergic differentiation in murine embryonic stem (ES) cell-derived spheres without dissociation. The knockdown of L3/Lhx8 gene expression dramatically decreased the cholinergic phenotype of spheres without altering other known phenotypes (TuJ1, GABA and GFAP). These results strongly suggest that L3/Lhx8 is a key factor for cholinergic differentiation of murine ES cell-derived spheres and is involved in basal forebrain development.

A novel role for Fyn: Change in sphere formation ability in murine embryonic stem cells

Fyn, a member of the Src-family protein tyrosine kinase (PTK), is an essential factor in myelination in the CNS and is involved in murine embryonic stem (ES) cell growth and differentiation. Although dysfunctions of Fyn have been comparatively studied, the gain of function by ectopic expression, especially using ES cells, has seldom been investigated. In this article, we give the first report of the involvement of Fyn alteration in the sphere formation ability of murine ES cells. First, transient transfection of Fyn hardly affected multiplication and specialization. Then, we investigated Fyn overexpression using ES cells, which stably express Fyn. As a result, altered sphere formation capability was observed in all clones stably expressing Fyn. These results may provide important information for reproduction medical treatment using ES cells.