Identification of a Smad4/YY1-recognized and BMP2-responsive transcriptional regulatory module in the promoter of mouse GABA transporter subtype I (Gat1) gene

Smurf2 exerts neuroprotective effects on cerebral ischemic injury

The present study aimed to explore specific mechanisms involved in mediating the neuroprotective effects of Smad ubiquitination regulatory factor 2 (Smurf2) in cerebral ischemic injury. A middle cerebral artery occlusion (MCAO) mouse model and an oxygen–glucose deprivation (OGD)–treated neuron model were developed. The expression of Smurf2, Yin Yang 1 (YY1), hypoxia-inducible factor-1 alpha (HIF1α), and DNA damage–inducible transcript 4 gene (DDIT4) was analyzed. Thereafter, the expression of Smurf2, YY1, HIF1α, and DDIT4 was altered in the MCAO mice and OGD-treated neurons. Apoptosis in tissues and cerebral infarction were assessed. In neurons, the expression of apoptosis-related proteins, viability, and apoptosis were assessed, followed by evaluation of lactate dehydrogenase leakage rate. The interaction between Smurf2 and YY1 was analyzed by coimmunoprecipitation assay and that between YY1 ubiquitination by in vivo ubiquitination experiment. The results showed downregulation of Smurf2 and upregulation of YY1, HIF1α, and DDIT4 in both MCAO mice and OGD-treated neurons. Smurf2 elevated YY1 ubiquitination and degradation, and YY1 increased HIF1α expression to promote DDIT4 in neurons. Overexpressed Smurf2 or downregulated YY1, HIF1α, or DDIT4 reduced the volume of cerebral infarction and apoptosis in MCAO mice, while enhancing cell viability and reducing apoptosis and lactate dehydrogenase leakage in OGD-treated neurons. In summary, our findings elucidated a neuroprotective role of Smurf2 in cerebral ischemic injury via inactivation of the YY1/HIF1α/DDIT4 axis.

Arfgef1 haploinsufficiency in mice alters neuronal endosome composition and decreases membrane surface postsynaptic GABAA receptors

ARFGEF1 encodes a guanine exchange factor involved in intracellular vesicle trafficking, and is a candidate gene for childhood genetic epilepsies. To model ARFGEF1 haploinsufficiency observed in a recent Lennox Gastaut Syndrome patient, we studied a frameshift mutation (Arfgef1^fs) in mice. Arfgef1^fs/+ pups exhibit signs of developmental delay, and Arfgef1^fs/+ adults have a significantly decreased threshold to induced seizures but do not experience spontaneous seizures. Histologically, the Arfgef1^fs/+ brain exhibits a disruption in the apical lining of the dentate gyrus and altered spine morphology of deep layer neurons. In primary hippocampal neuron culture, dendritic surface and synaptic but not total GABA_A receptors (GABA_AR) are reduced in Arfgef1^fs/+ neurons with an accompanying decrease in the number of GABA_AR-containing recycling endosomes in cell body. Arfgef1^fs/+ neurons also display differences in the relative ratio of Arf6⁺:Rab11⁺:TrfR⁺ recycling endosomes. Although the GABA_AR-containing early endosomes in Arfgef1^fs/+ neurons are comparable to wildtype, Arfgef1^fs/+ neurons show an increase in the number of GABA_AR-containing lysosomes in dendrite and cell body. Together, the altered endosome composition and decreased neuronal surface GABA_AR results suggests a mechanism whereby impaired neuronal inhibition leads to seizure susceptibility.

A role for miR-132 in learned safety

Learned safety is a fear inhibitory mechanism, which regulates fear responses, promotes episodes of safety and generates positive affective states. Despite its potential as experimental model for several psychiatric illnesses, including post-traumatic stress disorder and depression, the molecular mechanisms of learned safety remain poorly understood, We here investigated the molecular mediators of learned safety, focusing on the characterization of miRNA expression in the basolateral amygdala (BLA). Comparing levels of 22 miRNAs in learned safety and learned fear trained mice, six safety-related miRNAs, including three members of the miR-132/-212 family, were identified. A gain-of-function approach based upon in-vivo transfection of a specific miRNA mimic, and miR-132/212 knock-out mice as loss-of-function tool were used in order to determine the relevance of miR-132 for learned safety at the behavioral and the neuronal functional levels. Using a designated bioinformatic approach, PTEN and GAT1 were identified as potential novel miR-132 target genes and further experimentally validated. We here firstly provide evidence for a regulation of amygdala miRNA expression in learned safety and propose miR-132 as signature molecule to be considered in future preclinical and translational approaches testing the transdiagnostic relevance of learned safety as intermediate phenotype in fear and stress-related disorders.

SLC6A1-miR133a-CDX2 loop regulates SK-OV-3 ovarian cancer cell proliferation, migration and invasion

The present study assessed the expression of solute carrier 6 member 1 (SLC6A1) in ovarian cancer (OC) tissues and evaluated the effect of silencing SLC6A1 or caudal type homeobox 2 (CDX2) on the proliferation, migration, and invasion of SK-OV-3 OC cells. The levels of caudal type homeobox 2 (CDX2) and SLC6A1 mRNA were also examined in OC SK-OV-3, OVCAR3 and A2780 cell lines. The mRNA levels of CDX2 and SLC6A1 in SK-OV-3 OC cells were assessed following transection with microRNA (miR) 133a mimics; the mRNA and protein levels of SLC6A1 were determined following the silencing of CDX2, and the mRNA expression of CDX2 was gauged following the silencing of SLC6A1. A luciferase reporter assay was performed to assess the effect of miR133a on the CDX2 and SLC6A1 3′-untranslated regions (3′UTRs). The proliferation, migration and invasion rate of SK-OV-3 cells were then examined following the silencing of CDX2 or SLC6A1. The expression of SLC6A1 was increased in OC compared with adjacent tissue. The expression of CDX2 and SLC6A1 in SK-OV-3 and OVCAR3 cells was increased compared with A2780 cells (P<0.05). The level of CDX2 and SLC6A1 mRNA in SK-OV-3 cells decreased when the cells were transected with the miR133a mimics, compared with a negative control (P<0.05). Transfection with the miR133a mimics significantly reduced the luciferase activity of reporter plasmids with the SLC6A1 or CDX2 3′UTRs (P<0.05). The mRNA level of CDX2 was decreased subsequent to the silencing of SLC6A1; the mRNA and protein level of SLC6A1 were decreased when CDX2 was silenced (P<0.05). The proliferation, migration, and invasion of SK-OV-3 cells were significantly reduced following the silencing of CDX2 or SLC6A1 (P<0.05). CDX2 may therefore be inferred to promote the proliferation, migration and invasion in SK-OV-3 OC cells, acting as a competing endogenous RNA.

Crosstalk among electrical activity, trophic factors and morphogenetic proteins in the regulation of neurotransmitter phenotype specification

Morphogenetic proteins are responsible for patterning the embryonic nervous system by enabling cell proliferation that will populate all the neural structures and by specifying neural progenitors that imprint different identities in differentiating neurons. The adoption of specific neurotransmitter phenotypes is crucial for the progression of neuronal differentiation, enabling neurons to connect with each other and with target tissues. Preliminary neurotransmitter specification originates from morphogen-driven neural progenitor specification through the combinatorial expression of transcription factors according to morphogen concentration gradients, which progressively restrict the identity that born neurons adopt. However, neurotransmitter phenotype is not immutable, instead trophic factors released from target tissues and environmental stimuli change expression of neurotransmitter-synthesizing enzymes and specific vesicular transporters modifying neuronal neurotransmitter identity. Here we review studies identifying the mechanisms of catecholaminergic, GABAergic, glutamatergic, cholinergic and serotonergic early specification and of the plasticity of these neurotransmitter phenotypes during development and in the adult nervous system. The emergence of spontaneous electrical activity in developing neurons recruits morphogenetic proteins in the process of neurotransmitter phenotype plasticity, which ultimately equips the nervous system and the whole organism with adaptability for optimal performance in a changing environment.

Cloning and identification of a YY-1 homolog as a potential transcription factor from Pinctada fucata

Biomineralization is an important and ubiquitous process in organisms. The shell formation of mollusks is a typical biomineral physical activity and is used as a canonical model in biomineralization research. Most recent studies focused on the identification of matrix proteins involved in shell formation; however, little is known about their transcriptional regulation mechanism, especially the transcription factors involved in shell formation. In this study, we identified a homolog of the YY-1 transcriptional factor from Pinctada fucata, named Pf-YY-1, and characterized its expression pattern and biological functions. Pf-YY-1 has a typical zinc finger motif highly similar to those in humans, mice, and other higher organisms, which indicated its DNA-binding capability and its function as a transcription factor. Pf-YY-1 is ubiquitously expressed in many tissues, but at a higher level in the mantle, which suggested a role in biomineralization. The expression pattern of Pf-YY-1 during pearl sac development was quite similar to, and was synchronized with, those of Prisilkin-39, ACCBP, and other genes involved in biomineralization, which also suggested its function in biomineralization.

Use of stem cell transplantation to treat epilepsy: A Web of Science-based literature analysis

OBJECTIVE:

To identify global research trends in the use of stem cell transplantation to treat epilepsy.

DATA RETRIEVAL:

We performed a bibliometric analysis of studies on the use of stem cell transplantation to treat epilepsy during 2002–2011, retrieved from Web of Science, using the key words epilepsy or epileptic or epilepticus or seizure and “stem cell”.

SELECTION CRITERIA:

Inclusion criteria: (a) peer-reviewed published articles on the use of stem cell transplantation to treat epilepsy indexed in Web of Science; (b) original research articles, reviews, meeting abstracts, proceedings papers, book chapters, editorial material, and news items.

MAIN OUTCOME MEASURES:

(a) Annual publication output; (b) type of publication; (c) publication by research field; (d) publication by journal; (e) publication by author; (f) publication by country and institution; (g) publications by institution in China; (h) most-cited papers; and (i) papers published by Chinese authors or institutions.

RESULTS:

A total of 460 publications on the use of stem cell transplantation to treat epilepsy were retrieved from Web of Science, 2002–2011. The number of publications gradually increased over the 10-year study period. Articles and reviews constituted the major types of publications. More than half of the studies were in the field of neuroscience/neurology. The most prolific journals for this topic were Epilepsia, Bone Marrow Transplantation, and Journal of Neuroscience. Of the 460 publications, almost half came from American authors and institutions; relatively few papers were published by Chinese authors or institutions.

CONCLUSION:

Literature on stem cell transplantation for epilepsy includes many reports of basic research, but few of clinical trials or treatments. Exact effects are not yet evaluated. Epilepsy rehabilitation is a long-term, complex, and comprehensive system engineering. With advances in medical development, some effective medical, social and educational measures are needed to facilitate patient's treatment and training and accelerate the recovery of life ability, learning ability and social adaptability to the largest extent to improve patient's quality of life.