The transcription factors ZAT5 and BLH2/4 regulate homogalacturonan demethylesterification in Arabidopsis seed coat mucilage.

The level of methylesterification alters the functional properties of pectin, which is believed to influence plant growth and development. However, the mechanisms that regulate demethylesterification remain largely unexplored. Pectin with a high degree of methylesterification is produced in the Golgi apparatus and then transferred to the primary cell wall where it is partially demethylesterified by pectin methylesterases (PMEs). Here, we show that in Arabidopsis (Arabidopsis thaliana) seed mucilage, pectin demethylesterification is negatively regulated by the transcription factor ZINC FINGER FAMILY PROTEIN5 (ZAT5). Plants carrying null mutations in ZAT5 had increased PME activity, decreased pectin methylesterification, and produced seeds with a thinner mucilage layer. We provide evidence that ZAT5 binds to a TGATCA-motif and thereby negatively regulates methylesterification by reducing the expression of PME5, HIGHLY METHYL ESTERIFIED SEEDS (HMS)/PME6, PME12, and PME16. We also demonstrate that ZAT5 physically interacts with BEL1-LIKE HOMEODOMAIN2 (BLH2) and BLH4 transcription factors. BLH2 and BLH4 are known to modulate pectin demethylesterification by directly regulating PME58 expression. The ZAT5-BLH2/4 interaction provides a mechanism to control the degree of pectin methylesterification in seed coat mucilage by modifying each transcription factor's ability to regulate the expression of target genes encoding PMEs. Taken together, these findings reveal a transcriptional regulatory module comprising ZAT5, BLH2 and BLH4, that functions in modulating the de-methylesterification of homogalacturonan in seed coat mucilage.

Activation of Kv7 channels normalizes hyperactivity of the VTA-NAcLat circuit and attenuates methamphetamine-induced conditioned place preference and sensitization in mice.

The brain circuit projecting from the ventral tegmental area (VTA) to the nucleus accumbens lateral shell (NAcLat) has a key role in methamphetamine (MA) addiction. As different dopamine (DA) neuron subpopulations in the VTA participate in different neuronal circuits, it is a challenge to isolate these DA neuron subtypes. Using retrograde tracing and Patch-seq, we isolated DA neurons in the VTA-NAcLat circuit in MA-treated mice and performed gene expression profiling. Among the differentially expressed genes, KCNQ genes were dramatically downregulated. KCNQ genes encode Kv7 channel proteins, which modulate neuronal excitability. Injection of both the Kv7.2/3 agonist ICA069673 and the Kv7.4 agonist fasudil into the VTA attenuated MA-induced conditioned place preference and locomotor sensitization and decreased neuronal excitability. Increasing Kv7.2/3 activity decreased neural oscillations, synaptic plasticity and DA release in the VTA-NacLat circuit in MA-treated mice. Furthermore, overexpression of only Kv7.3 channels in the VTA-NacLat circuit was sufficient to attenuate MA-induced reward behavior and decrease VTA neuron excitability. Activation of Kv7 channels in the VTA may become a novel treatment strategy for MA abuse.

Systematic pan-cancer analysis identifies transmembrane protein 158 as a potential therapeutic, prognostic and immunological biomarker.

The purpose of this study was to investigate the expression significance, predictive value, immunologic function, and biological role of transmembrane protein 158 (TMEM158) in the development of pan-cancer. To achieve this, we utilized data from multiple databases, including TCGA, GTEx, GEPIA, and TIMER, to collect gene transcriptome, patient prognosis, and tumor immune data. We evaluated the association of TMEM158 with patient prognosis, tumor mutational burden (TMB), and microsatellite instability (MSI) in pan-cancer samples. We performed immune checkpoint gene co-expression analysis and gene set enrichment analysis (GSEA) to better understand the immunologic function of TMEM158. Our findings revealed that TMEM158 was significantly differentially expressed between most types of cancer tissues and their adjacent normal tissues and was associated with prognosis. Moreover, TMEM158 was significantly correlated with TMB, MSI, and tumor immune cell infiltration in multiple cancers. Co-expression analysis of immune checkpoint genes showed that TMEM158 was related to the expression of several common immune checkpoint genes, especially CTLA4 and LAG3. Gene enrichment analysis further revealed that TMEM158 was involved in multiple immune-related biological pathways in pan-cancer. Overall, this systematic pan-cancer analysis suggests that TMEM158 is generally highly expressed in various cancer tissues and is closely related to patient prognosis and survival across multiple cancer types. TMEM158 may serve as a significant predictor of cancer prognosis and modulate immune responses to various types of cancer.

Dopamine D1 receptor in orbitofrontal cortex to dorsal striatum pathway modulates methamphetamine addiction.

The orbitofrontal cortex (OFC)-dorsal striatum (DS) is an important neural circuit that contributes to addictive behavior, including compulsive reinforcement, yet the specific types of neurons that play a major role still need to be further elucidated. Here, we used a place conditioning paradigm to measure the conditioned responses to methamphetamine (MA). The results demonstrated that MA increases the expression of c-Fos, synaptic plasticity in OFC and DS. Patch-clamp recording showed that MA activated projection neurons from the OFC to the DS, and chemogenetic manipulation of neuronal activity in OFC-DS projection neurons affects conditioned place preference (CPP) scores. And the combined patch-electrochemical technique was used to detect the DA release in OFC, the data indicated that the DA release was increased in MA group. Additionally, SCH23390, a D1R antagonist, was used to verify the function of D1R projection neurons, showing that SCH23390 reversed MA addiction-like behavior. Collectively, these findings provide evidence for the D1R neuron is sufficient to regulate MA addiction in the OFC-DS pathway, and the study provides new insight into the underlying mechanism of pathological changes in MA addiction.

Inactivation of the Lateral Hypothalamus Attenuates Methamphetamine-Induced Conditioned Place Preference through Regulation of Kcnq3 Expression.

Repeated administration of methylamphetamine (MA) induces MA addiction, which is featured by awfully unpleasant physical and emotional experiences after drug use is terminated. Neurophysiological studies show that the lateral hypothalamus (LH) is involved in reward development and addictive behaviors. Here, we show that repeated administration of MA activates the expression of c-Fos in LH neurons responding to conditioned place preference (CPP). Chemogenetic inhibition of the LH can disrupt the addiction behavior, demonstrating that the LH plays an important role in MA-induced reward processing. Critically, MA remodels the neurons of LH synaptic plasticity, increases intracellular calcium level, and enhances spontaneous current and evoked potentials of neurons compared to the saline group. Furthermore, overexpression of the potassium voltage-gated channel subfamily Q member 3 (Kcnq3) expression can reverse the CPP score and alleviate the occurrence of addictive behaviors. Together, these results unravel a new neurobiological mechanism underlying the MA-induced addiction in the lateral hypothalamus, which could pave the way toward new and effective interventions for this addiction disease.

Lactate: A Novel Signaling Molecule in Synaptic Plasticity and Drug Addiction.

l-Lactate is emerging as a crucial regulatory nexus for energy metabolism in the brain and signaling transduction in synaptic plasticity, memory processes, and drug addiction instead of being merely a waste by-product of anaerobic glycolysis. In this review, the role of lactate in various memory processes, synapse plasticity and drug addiction on the basis of recent studies is summarized and discussed. To this end, three main parts are presented: first, lactate as an energy substrate in energy metabolism of the brain is described; second, lactate as a novel signaling molecule in synaptic plasticity, neural circuits, memory, and drug addiction is described; and third, in light of the above descriptions, it is plausible to speculate that lactate is predominantly a signaling molecule in specific memory processes and partly acts as an energy substrate. The future perspective in lactate signaling involving microglia and associated precise signaling pathways in the brain is highlighted.

Astragalus protects PC12 cells from 6-hydroxydopamine-induced neuronal damage: A serum pharmacological study.

Accumulating evidence has already indicated that traditional Chinese medicine (TCM) possesses tremendous potential for treating neurodegenerative diseases. Astragalus, also named Huangqi, is a famous traditional medical herb that can be applied to treat cerebral ischemia and prevent neuronal degeneration. Nevertheless, the underlying mechanisms remain largely unexplored. In the present study, Astragalus-containing serum (ASMES) was prepared and added into the culture medium of PC12 cells to explore its neuroprotective effect on 6-hydroxydopamine (6-OHDA)-caused neuronal toxicity. Our data showed that ASMES significantly ameliorated the cellular viability of cultured PC12 cells against the neurotoxicity induced by 6-OHDA (P < 0.05). Moreover, ASMES significantly decreased the cell apoptosis triggered by 6-OHDA (P < 0.01). Furthermore, 2',7'-dichlorofluorescin diacetate assay was performed to detect the changes in oxidative stress, and we showed that 6-OHDA elevated the production of reactive oxygen species (ROS), whereas ASMES significantly reversed these changes (P < 0.01). Besides, mitochondrial membrane potential (MMP) assay showed that ASMES could restore 6-OHDA-damaged MMP in cultured PC12 cells (P < 0.05). In conclusion, Astragalus could protect PC12 cells from 6-OHDA-caused neuronal toxicity, and possibly, the ROS-mediated apoptotic pathway participated in this process. Collectively, our findings provided valuable insights into the potential in treatment of neurodegenerative diseases.

Nicotinamide adenine dinucleotide promotes synaptic plasticity gene expression through regulation N-methyl-D-aspartate receptor/Ca2+/Erk1/2 pathway.

Nicotinamide adenine dinucleotide (NADH) has been reported to regulate synaptic plasticity recently, while its role in this process remains unclear. To explore the contribution and the underlying mechanisms of NADH regulating synaptic plasticity, here, we examined NADH's effect on immediate-early response genes (IEGs) expressions, including C-Fos and Arc in primary cultured cortical neurons and the frontal cortex of mouse brain. Our results showed that NADH promoted IEGs expression and that the C-Fos and Arc levels are increased in primary cultured cortical neurons, which is almost completely blocked by N-methyl-D-aspartate receptor (NMDAR) inhibitor, MK-801. Moreover, NADH significantly increased intracellular Ca2+ levels and the phosphorylation of Erk1/2, a downstream molecule of the NMDAR. Furthermore, NADH also significantly increased IEGs expression in vivo, accompanied by the changes of Ca2+ in neurons and activation of excitatory neurons in the mouse frontal cortex. In conclusion, this study indicates that NADH can promote the expression of synaptic plasticity-related IEGs through the NMDAR/Ca2+/Erk1/2 pathway, which provides a new way to understand the regulatory role of NADH in synaptic plasticity.

Potato NAC Transcription Factor StNAC053 Enhances Salt and Drought Tolerance in Transgenic Arabidopsis.

The NAC (NAM, ATAF1/2, and CUC2) transcription factors comprise one of the largest transcription factor families in plants and play important roles in stress responses. However, little is known about the functions of potato NAC family members. Here we report the cloning of a potato NAC transcription factor gene StNAC053, which was significantly upregulated after salt, drought, and abscisic acid treatments. Furthermore, the StNAC053-GFP fusion protein was found to be located in the nucleus and had a C-terminal transactivation domain, implying that StNAC053 may function as a transcriptional activator in potato. Notably, Arabidopsis plants overexpressing StNAC053 displayed lower seed germination rates compared to wild-type under exogenous ABA treatment. In addition, the StNAC053 overexpression Arabidopsis lines displayed significantly increased tolerance to salt and drought stress treatments. Moreover, the StNAC053-OE lines were found to have higher activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) under multiple stress treatments. Interestingly, the expression levels of several stress-related genes including COR15A,DREB1A, ERD11, RAB18, ERF5, and KAT2, were significantly upregulated in these StNAC053-overexpressing lines. Taken together, overexpression of the stress-inducible StNAC053 gene could enhance the tolerances to both salt and drought stress treatments in Arabidopsis, likely by upregulating stress-related genes.

Melatonin recovers sleep phase delayed by MK-801 through the melatonin MT2 receptor- Ca2+ -CaMKII-CREB pathway in the ventrolateral preoptic nucleus.

Melatonin (MLT) is widely used to treat sleep disorders although the underlying mechanism is still elusive. In mice, using wheel-running detection, we found that exogenous MLT could completely recover the period length prolonged by N-methyl-D-aspartate receptor (NMDAR) impairment due to the injection of the NMDAR antagonist MK-801, a preclinical model of psychosis. The analysis of the possible underlying mechanisms indicated that MLT could regulate the homeostatic state in the ventrolateral preoptic nucleus (VLPO) instead of the circadian process in the suprachiasmatic nucleus (SCN). In addition, our data showed that MK-801 decreased Ca2+ -related CaMKII expression and CREB phosphorylation levels in the VLPO, and MLT could rescue these intracellular impairments but not NMDAR expression levels. Accordingly, Gcamp6 AAV virus was injected in-vivo to further monitor intracellular Ca2+ levels in the VLPO, and MLT demonstrated a unique ability to increase Ca2+ fluorescence compared with MK-801-injected mice. Additionally, using the selective melatonin MT2 receptor antagonist 4-phenyl-2-propionamidotetralin (4P-PDOT), we discovered that the pharmacological effects of MLT upon NMDAR impairments were mediated by melatonin MT2 receptors. Using electroencephalography/electromyography (EEG/EMG) recordings, we observed that the latency to the first nonrapid eye movement (NREM) sleep episode was delayed by MK-801, and MLT was able to recover this delay. In conclusion, exogenous MLT by acting upon melatonin MT2 receptors rescues sleep phase delayed by NMDAR impairment via increasing intracellular Ca2+ signaling in the VLPO, suggesting a regulatory role of the neurohormone on the homeostatic system.

Co-culturing on dry filter paper significantly increased the efficiency of Agrobacterium-mediated transformations of maize immature embryos.

In the Agrobacterium tumefaciens-mediated transformations of maize immature embryos (IEs), the common co-culturing media used are MS or N6-based (MC). Here, we used a novel co-culturing method in which maize 'Qi319' IEs inoculated with Agrobacterium-harboring target vector were placed on dry filter paper (DC) in a petri dish. To compare the effects of the DC and MC co-culturing methods on transformation efficiency, we designed three experiments: (1) A. tumefaciens strain AGL1 independently carrying two plasmids, pXQD12 and pXQD70; (2) two A. tumefaciens strains, AGL1 and EHA105, carrying pXQD12; and (3) strains AGL1 and EHA105 each independently inoculated with pXQD12 and pXQD70 for different infiltration periods, 5, 10, 15, 20 and 25 min. We used A. tumefaciens to inoculate IEs derived from maize ears 9-15 d after pollination, and then IEs were placed in petri dishes for co-culturing. The DC treatment significantly increased the percentage of IEs expressing green fluorescence protein (%GFP), indicating positive transformants. DC-treated IEs had ~ 3 to 4 times the %GFP compared with MC-treated IEs at 8 d after inoculation (3 d co-culture and 5 d restoration). The average regeneration frequency (%GFP positive regenerated calli of infected IEs) and stable transformation frequency (%GFP positive T0 plants of infected IEs) significantly increased with the DC treatment. Thus, the DC method may be used to develop a more efficient Agrobacterium-mediated transformation method for maize IEs.

Sohlh1 suppresses glioblastoma cell proliferation, migration, and invasion by inhibition of Wnt/ß-catenin signaling.

Glioblastoma (GBM) is the most aggressive and highly invasive type of astrocytic tumors. Despite advances in diagnosis and therapy, the prognosis and survival time remain poor. Identifying key mediators of tumor cell proliferation, migration, and invasion is crucial to the development of new and more effective therapies. In this paper, we report the novel role of Spermatogenesis- and oogenesis- specific basic helix-loop-helix transcription factor1 (Sohlh1) in the inhibition of Wnt/ß-catenin signaling and aggressive behaviors in GBM cells. Immunohistochemistry was performed to examine the expression of Sohlh1 and related proteins in astrocytomas. Human glioblastoma U87 and U251 cellswere transfected with appropriate plasmids and/or siRNAs to evaluate their functions on cell proliferation, migration, and invasion. Western blot and TOPflash luciferase assay were used to determine the involvement of Wnt/ß-catenin signaling pathway in Sohlh1-mediated cellular activities in glioblastomas. We observed that Sohlh1 was downregulated in astrocytomas. The reduction in Sohlh1 expression was inversely correlated with the degree of malignancy in astrocytomas. In GBM cell lines, cellular proliferation, migration, and invasion were significantly enhanced after Sohlh1 knockdown, but significantly inhibited after Sohlh1 overexpression. These functional effects of Sohlh1 were achieved by upregulating GSK3ß and inhibiting Wnt/ß-catenin signaling. Our findings provide novel mechanistic insights of Sohlh1 in malignant progression of astrocytomas, suggesting that the level of Sohlh1 expression may be a predictor of astrocytoma behavior and further, Sohlh1 may serve as a potential therapeutic target for GBM.

Fecal Microbiota Transplantation from Healthy Donors Reduced Alcohol-induced Anxiety and Depression in an Animal Model of Chronic Alcohol Exposure.

Alcohol addiction can cause brain dysfunction and threatens both individuals and society. Recently, emerging studies have suggested the dysbiosis of gut microbiota induced by alcohol exposure contributed to the reward-seeking behaviors as well as anxiety, depression. In the current study, animal model of chronic alcohol exposure was established by providing mice with gradient concentrations of alcohol from 2%, 4%, and 6% to 8% for 21 days. Moreover, three fecal microbiota transplantation (FMT) plans were innovatively designed to explore the potential effects of FMT from 3 healthy donors on alcohol-induced neuropsychic behaviors. To our knowledge, for the first time, we found that anxiety and depression after alcohol intake were gradually relieved with the extension of transplantation. Although the two-week FMT starting at the end of alcohol treatment had few effects, the transplantation started at 8% ethanol exposure alleviated alcohol-induced depression in tail suspension test. More importantly, accompanied by three-week exposure, the five-week FMT significantly decreased anxiety-like behaviors in open field test and depression in tail suspension test. These data validated the role of gut microbiota in alcohol addiction and indicated the modulation of healthy donor FMT on alcohol-related anxiety and depression, providing a new target for treating alcohol addiction by targeting microbiota.

Sohlh2 inhibits human ovarian cancer cell invasion and metastasis by transcriptional inactivation of MMP9.

Identifying key mediators of cancer invasion and metastasis is crucial to the development of new and more effective therapies. We previously identified Sohlh2 as an important inhibitor of ovarian cancer cell proliferation. However, the function of Sohlh2 in cell migration and invasion remains unknown. In this paper, we report a novel Sohlh2 to MMP9 signaling pathway in the invasive ovarian cancer. Using immunohistochemistry staining, we revealed Sohlh2 expression was inversely correlated with the invasive human ovarian cancers. In vitro experiments, forced expression of Sohlh2 led to a significant reduction in cancer cell migration and invasion. Conversely, silencing of Sohlh2 enhanced ovarian cancer cell migration and invasion. Experiments using nude mice demonstrated that the ectopic Sohlh2 expression inhibited the HO8910 cell capability of the metastasis to the lungs and livers. Ectopic overexpression of Sohlh2 in the invasive HO8910 cells reduced the MMP9 expression, whereas Sohlh2 knockdown from the non-invasive, SKOV3 cells increased the MMP9 expression. Promoter activation and binding analyses indicated that Sohlh2 repressed the MMP9 expression by directly acting on the MMP9 gene promoter. Inhibition of MMP9 dramatically blocked the Sohlh2 knockdown-enhanced SKOV3 cell invasion, and ectopic expression of MMP9 compensated for the anti-invasive activity of Sohlh2 in HO8910 cells. Overall, these results demonstrate for the first time that Sohlh2 functions as a tumor metastasis suppressor. Modulation of Sohlh2 expression has the potential to be a target for cancer therapy. © 2015 Wiley Periodicals, Inc.

Functional conservation and diversification of APETALA1/FRUITFULL genes in Brachypodium distachyon.

The duplicated grass APETALA1/FRUITFULL (AP1/FUL) genes have distinct but overlapping patterns of expression, suggesting their discrete roles in transition to flowering, specification of spikelet meristem identity and specification of floral organ identity. In this study, we analyzed the expression patterns and functions of four AP1/FUL paralogs (BdVRN1, BdFUL2, BdFUL3 and BdFUL4) in Brachypodium distachyon, a model plant for the temperate cereals and related grasses. Among the four genes tested, only BdVRN1 could remember the prolonged cold treatment. The recently duplicated BdVRN1 and BdFUL2 genes were expressed in a highly consistent manner and ectopic expressions of them caused similar phenotypes such as extremely early flowering and severe morphological alterations of floral organs, indicating their redundant roles in floral transition, inflorescence development and floral organ identity. In comparison, ectopic expressions of BdFUL3 and BdFUL4 only caused a moderate early flowering phenotype, suggesting their divergent function. In yeast two-hybrid assay, both BdVRN1 and BdFUL2 physically interact with SEP proteins but only BdFUL2 is able to form a homodimer. BdVRN1 also interacts weakly with BdFUL2. Our results indicate that, since the separation of AP1/FUL genes in grasses, the process of sub- or neo-functionalization has occurred and paralogs function redundantly and/or separately in flowering competence and inflorescence development.

Roles of NAD in Protection of Axon against Degeneration via SIRT1 Pathways.

Axonal degeneration is a common pathological change of neurogenical disease which often arises before the neuron death. But it had not found any effective method to protect axon from degeneration. In this study we intended to confirm the protective effect of nicotinamide adenine dinucleotide (NAD), investigate the optimal administration dosage and time of NAD, and identify the relationship between silence signal regulating factor 1 (SIRT1) and axonal degeneration. An axonal degeneration model was established using dorsal root ganglion (DRG) neurons injured by vincristine to observe the protective effects of NAD to the injured axons. In addition, the potential contribution of the SIRT1 in axonal degeneration was also investigated. Through the 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, immunochemistry staining, axons counting and length measuring, transmission electron microscope (TEM) observation, we demonstrated that NAD played an important role in preventing axonal degeneration. Further study revealed that the expression of SIRT1 and phosphorylated Akt1 (p-Akt1) was up-regulated when NAD was added into the culturing medium. Taking together, our results demonstrated that NAD might delay the axonal degeneration through SIRT1/Akt1 pathways.

Lithium protects against methamphetamine-induced neurotoxicity in PC12 cells via Akt/GSK3ß/mTOR pathway.

Methamphetamine (MA) is neurotoxic, especially in dopaminergic neurons. Long-lasting exposure to MA causes psychosis and increases the risk of Parkinson's disease. Lithium (Li) is a known mood stabilizer and has neuroprotective effects. Previous studies suggest that MA exposure decreases the phosphorylation of Akt/GSK3ß pathway in vivo, whereas Li facilitates the phosphorylation of Akt/GSK3ß pathway. Moreover, GSK3ß and mTOR are implicated in the locomotor sensitization induced by psychostimulants and mTOR plays a critical role in MA induced toxicity. However, the effect of MA on Akt/GSK3ß/mTOR pathway has not been fully investigated in vitro. Here, we found that MA exposure significantly dephosphorylated Akt/GSK3ß/mTOR pathway in PC12 cells. In addition, Li remarkably attenuated the dephosphorylation effect of MA exposure on Akt/GSK3ß/mTOR pathway. Furthermore, Li showed obvious protective effects against MA toxicity and LY294002 (Akt inhibitor) suppressed the protective effects of Li. Together, MA exposure dephosphorylates Akt/GSK3ß/mTOR pathway in vitro, while lithium protects against MA-induced neurotoxicity via phosphorylation of Akt/GSK3ß/mTOR pathway.

Astrocyte-like cells differentiated from a novel population of CD45-positive cells in adult human peripheral blood.

We have previously reported a novel CD45-positive cell population called peripheral blood insulin-producing cells (PB-IPCs) and its unique potential for releasing insulin in vitro. Despite the CD45-positive phenotype and self-renewal ability, PB-IPCs are distinguished from hemopoietic and endothelial progenitor cells (EPCs) by some characteristics, such as a CD34-negative phenotype and different culture conditions. We have further identified the gene profiles of the embryonic and neural stem cells, and these profiles include Sox2, Nanog, c-Myc, Klf4, Notch1 and Mash1. After treatment with all-trans retinoic acid (ATRA) in vitro, most PB-IPCs exhibited morphological changes that included the development of elongated and branched cell processes. In the process of induction, the mRNA expression of Hes1 was robustly upregulated, and a majority of cells acquired some astrocyte-associated specific phenotypes including anti-glial fibrillary acidic protein (GFAP), CD44, Glutamate-aspartate transporter (GLAST) and S100ß. In spite of the deficiency of glutamate uptaking, the differentiated cells significantly relaxed the regulation of the expression of brain-derived neurotrophic factor (BDNF) mRNA. This finding demonstrates that PB-IPCs could be induced into a population of astrocyte-like cells and enhanced the neurotrophic potential when the state of proliferation was limited by ATRA, which implies that this unique CD45+ cell pool may have a protective role in some degenerative diseases of the central nervous system (CNS).

Sohlh2 inhibits ovarian cancer cell proliferation by upregulation of p21 and downregulation of cyclin D1.

Spermatogenesis and oogenesis basic helix-loop-helix (bHLH) transcription factor 2 (Sohlh2) functions as a bhlh transcription factor to regulate mouse germ cell differentiation. Our previous data showed that Sohlh2 was highly expressed in human normal tissues, but low level of Sohlh2 was observed in many cancer cell lines, suggesting a possible role of Sohlh2 in tumorigenesis. In this study, we examined this possibility by using immunohistochemistry, MTT, 5-bromo-2-deoxyuridine, clonogenic assay and tumor xenograft techniques. Our results showed that the expression of Sohlh2 was decreased in epithelial ovarian carcinoma (EOC) tissues compared with benign ovarian tumors and ovarian tumors with low malignant potential. Forced expression of Sohlh2 led to a significant reduction in cancer cell proliferation in vitro and tumorigenesis in nude mice. Conversely, silencing of Sohlh2 enhanced ovarian cancer cell proliferation. Furthermore, Sohlh2 had opposite effects on its two direct targets p21 and cyclin D1: overexpression of Sohlh2 upregulated p21 but downregulated cyclin D1 expression. p21 knockdown could reverse the effects of Sohlh2 overexpression on inhibiting cell proliferation, and cyclin D1 knockdown could reverse the effects of Sohlh2 ablation on promoting cell proliferation. Thus, our data indicate that Sohlh2 likely functions as a tumor suppressor in EOCs, which is achieved by inducing p21 expression but repressing cyclin D1 expression.