No abstract

MicroRNA-153 (miR-153) is a brain-specific miRNA that is expressed at a significantly lower level in glioblastoma (GBM) relative to non-neoplastic brain tissue. Although the expression pattern of miR-153 has been extensively established, its target genes and cellular mechanism remain undefined. To investigate into the potential function of miR-153 in glioblastmas, we transfected a GBM cell line DBTRG-05MG with synthetic miR-153 oligos and observed decreased cell proliferation and increased apoptosis. Bioinformatics analysis revealed that anti-apoptosis family member B-cell lymphoma 2 (Bcl-2) and myeloid cell leukemia sequence 1 (Mcl-1) are potential targets of miR-153. Indeed, Western blot analysis indicated that miR-153 downregulated both Bcl-2 and Mcl-1 at the protein levels. Single strand miR-153 inhibitor, which forms complementary base-pair with endogenous miR-153, efficiently blocked the apoptosis and target protein degradation induced by overexpression of miR-153. By luciferase reporter assays, we further showed that miR-153 inhibited Bcl-2 and Mcl-1 expressions by directly targeting the 3 0 UTR regions of their respective mRNAs.

During the early postnatal period, environmental influences play a pivotal role in shaping the development of the neocortex, including the prefrontal cortex (PFC) that is crucial for working memory and goal-directed actions. Exposure to stressful experiences during this critical period may disrupt the development of PFC pyramidal neurons and impair the wiring and function of related neural circuits. However, the molecular mechanisms of the impact of early-life stress on PFC development and function are not well understood. In this study, we found that repeated stress exposure during the first postnatal week hampered dendritic development in layers II/III and V pyramidal neurons in the dorsal agranular cingulate cortex (ACd) and prelimbic cortex (PL) of neonatal mice. The deleterious effects of early postnatal stress on structural plasticity persisted to adulthood only in ACd layer V pyramidal neurons. Most importantly, concurrent blockade of corticotropin-releasing factor receptor 1 (CRF 1 ) by systemic antalarmin administration (20 mg/g of body weight) during early-life stress exposure prevented stress-induced apical dendritic retraction and spine loss in ACd layer V neurons and impairments in PFC-dependent cognitive tasks. Moreover, the magnitude of dendritic regression, especially the shrinkage of apical branches, of ACd layer V neurons predicted the degree of cognitive deficits in stressed mice. Our data highlight the region-specific effects of early postnatal stress on the structural plasticity of prefrontal pyramidal neurons, and suggest a critical role of CRF 1 in modulating early-life stress-induced prefrontal abnormalities.

Adult individuals with early stressful experience exhibit impaired hippocampal neuronal morphology, synaptic plasticity and cognitive performance. While our knowledge on the persistent effects of early-life stress on hippocampal structure and function and the underlying mechanisms has advanced over the recent years, the molecular basis of the immediate postnatal stress effects on hippocampal development remains to be investigated. Here, we reported that repeated blockade of corticotropin-releasing hormone receptor 1 (CRHR1) ameliorated postnatal stress-induced hippocampal synaptic abnormalities in neonatal mice. Following the stress exposure, pups with fragmented maternal care showed retarded dendritic outgrowth and spine formation in CA3 pyramidal neurons and reduced hippocampal levels of synapse-related proteins. During the stress exposure, repeated blockade of glucocorticoid receptors (GRs) by daily administration of RU486 (100 µg g(-1) ) failed to attenuate postnatal stress-evoked synaptic impairments. Conversely, daily administration of the CRHR1 antagonist antalarmin hydrochloride (20 µg g(-1) ) in stressed pups normalized hippocampal protein levels of synaptophysin, postsynaptic density-95, nectin-1, and nectin-3, but not the N-methyl-d-aspartate receptor subunits NR1 and NR2A. Additionally, GR or CRHR1 antagonism attenuated postnatal stress-induced endocrine alterations but not body growth retardation. Our data indicate that the CRH-CRHR1 system modulates the deleterious effects of early-life stress on dendritic development, spinogenesis, and synapse formation, and that early interventions of this system may prevent stress-induced hippocampal maldevelopment.

Calbindin modulates intracellular Ca dynamics and synaptic plasticity. Reduction of hippocampal calbindin levels has been implicated in early-life stress-related cognitive disorders, but it remains unclear how calbindin in distinct populations of hippocampal neurons contributes to stress-induced memory loss. Here we report that early-life stress suppressed calbindin levels in CA1 and dentate gyrus (DG) neurons, and calbindin knockdown in adult CA1 or DG excitatory neurons mimicked early-life stress-induced memory loss. In contrast, calbindin knockdown in CA1 interneurons preserved long-term memory even after an acute stress challenge. These results indicate that the dysregulation of calbindin in hippocampal excitatory, but not inhibitory, neurons conveys susceptibility to stress-induced memory deficits. Moreover, calbindin levels were downregulated by early-life stress through the corticotropin-releasing hormone receptor 1-nectin3 pathway, which in turn reduced inositol monophosphatase levels. Our findings highlight calbindin as a molecular target of early-life stress and an essential substrate for memory.

Angiogenesis is a key step for tumour growth and metastasis, and anti-angiogenesis has been proposed as an important strategy for cancer therapy. Tryptanthrin is a weakly basic alkaloid isolated from the dried roots of medicinal indigo plants and has been shown to possess anti-tumour activities on various cancer cell types. This study aims to investigate the in vitro and in vivo anti-angiogenic activities of tryptanthrin and to unravel its underlying molecular action mechanisms. Our results show that tryptanthrin inhibited the in vitro proliferation, migration, and tube formation of the human microvascular endothelial cells (HMEC-1) in a concentration-dependent manner and significantly suppressed angiogenesis in Matrigel plugs in mice. Mechanistic studies indicated that tryptanthrin reduced the expression of several pro-angiogenic factors (Ang-1, PDGFB and MMP2). Tryptanthrin was also found to suppress the VEGFR2-mediated ERK1/2 signalling pathway in HMEC-1 cells and molecular docking simulation indicated that tryptanthrin could bound to the ATP-binding site of VEGFR2. Collectively, the present study demonstrated that tryptanthrin exhibited both in vitro and in vivo anti-angiogenic activities by targeting the VEGFR2-mediated ERK1/2 signalling pathway and might have therapeutic potential for the treatment of angiogenesis-related diseases.

MicroRNAs (miRNAs) are noncoding RNAs that regulate gene expression by inhibiting translation or by promoting mRNA degradation. Previously, we established that microRNA-153 (miR-153) induces apoptosis by downregulating B-cell lymphoma 2 (Bcl-2) and myeloid cell leukemia sequence 1 (Mcl-1) protein expression levels in glioblastoma cell line DBTRG-05MG. In our study, we show that ectopic expression of miR-153 also inhibits the protein kinase B (PKB/Akt) pathway via reducing the protein level of insulin receptor substrate-2 (Irs-2). Moreover, simultaneous treatment with the chromatin-modifying drugs 4-phenylbutyric acid and 5-aza-2 0 -deoxycytidine induces miR-153 expression to suppress Irs-2, Bcl-2 and Mcl-1 expressions, thus downregulating the survival but upregulating the apoptotic pathways, implying that tumor suppressor miR-153 is a dual life and death regulator.miRNAs are a class of noncoding RNA involved in post-transcriptional gene regulation. 1 miRNAs generally can downregulate targets genes with complementary sites in the 3 0 -untranslated region. miRNAs play important regulatory roles in a broad range of biological processes. For example, micro-RNA-21 (miR-21), the expression level of which is significantly elevated in cancers, regulates multiple genes associated with apoptosis, migration and invasion. 2,3 Glioblastoma (GBM) is a fatal central nervous system (CNS) tumor and considered to be among the deadliest form of human cancers. 4 Recently, several reports have revealed that abnormal miRNA expression is involved in GBM. 5,6 Specifically, a brain-specific miRNA, miR-153, was found to be highly expressed in normal brain tissue but almost at undetectable levels in malignant gliomas or CNS tumor-derived cell lines, suggesting that miR-153 functions as a tumor suppressor. [5][6][7] On the basis of a glioblastoma multiforme cell line DBTRG-05MG, we previously showed that enforced expression of miR-153 increases apoptosis via targeting two antiapoptosis family members B-cell lymphoma 2 (Bcl-2) and myeloid cell leukemia sequence 1 (Mcl-1), linking this tumor suppressor to the apoptosis pathway. Besides the apoptosis pathway, cellular life and death decision also hinges on the phosphatidylinositol 3-kinase (PI3K) and protein kinase B (PKB/Akt) survival pathway.9 Tumor suppressor miR-7 has been shown to inhibit the PI3K/Akt pathway via targeting upstream signaling molecules such as epidermal growth factor receptor (Egfr) and insulin receptor substrates-1/2 (Irs-1/2). 10 We, thus, wonder if tumor suppressor miR-153 additionally regulates the survival pathway. In our study, we report that miR-153 directly downregulates Irs-2 and consequently inhibits Akt phosphorylation. Moreover, miR-153 is upregulated to suppress Irs-2, Bcl-2 and Mcl-1 expressions by simultaneous treatment with the histone deacetylase inhibitor 4-phenylbutyric acid (PBA) and DNAdemethylating agent 5-aza-2 0 -deoxycytidine (DAC), thus downregulating the survival but upregulating the apoptotic pathways, implying that tumor suppressor miR-153 is ...

MYCN-amplified neuroblastoma (NB) is characterized by poor prognosis, and directly targeting MYCN has proven challenging. Here, we showed that aldehyde dehydrogenase family 18 member A1 (ALDH18A1) exerts profound impacts on the proliferation, self-renewal, and tumorigenicity of NB cells and is a potential risk factor in patients with NB, especially those with MYCN amplification. Mechanistic studies revealed that ALDH18A1 could both transcriptionally and posttranscriptionally regulate MYCN expression, with MYCN reciprocally transactivating ALDH18A1 and thus forming a positive feedback loop. Using molecular docking and screening, we identified an ALDH18A1-specific inhibitor, YG1702, and demonstrated that pharmacological inhibition of ALDH18A1 was sufficient to induce a less proliferative phenotype and confer tumor regression and prolonged survival in NB xenograft models, providing therapeutic insights into the disruption of this reciprocal regulatory loop in MYCN-amplified NB.