NF-kappa B mediated Up-regulation of CCCTC-binding factor in pediatric acute lymphoblastic leukemia

BACKGROUND: Acute lymphoblastic leukemia (ALL) is the most frequently occurring malignant neoplasm in children. Despite advances in treatment and outcomes for ALL patients, the pathogenesis of the disease remains unclear. Microarray analysis of samples from 100 Chinese children with ALL revealed the up-regulation of CTCF (CCCTC binding factor). CTCF is a highly conserved 11-zinc finger protein that is involved in many human cancers; however, the biological function of CTCF in pediatric ALL is unknown. METHODS: The expression patterns of CTCF were evaluated in matched newly diagnosed (ND), complete remission (CR), and relapsed (RE) bone marrow samples from 28 patients. The potential oncogenic mechanism of CTCF and related pathways in leukemogenesis were investigated in leukemia cell lines. RESULTS: We identified significant up-regulation of CTCF in the ND samples. Importantly, the expression of CTCF returned to normal levels after CR but rebounded in the RE samples. In the pre-B ALL cell line Nalm-6, siRNA-mediated silencing of CTCF expression promoted cell apoptosis and reduced cell proliferation; accordingly, over-expression of a cDNA encoding full-length CTCF protected cells from apoptosis and enhanced cell proliferation. Furthermore, inhibition or activation of the nuclear factor-kappa B (NF-κB) pathway resulted in marked variations in the levels of CTCF mRNA and protein in leukemic cells, indicating that CTCF may be involved downstream of the NF-κB pathway. Moreover, inhibition of the NF-κB pathway increased cell apoptosis, which was partially rescued by ectopic over-expression of CTCF, suggesting that CTCF may play a significant role in the anti-apoptotic pathway mediated by NF-κB. CONCLUSIONS: Our results indicate that CTCF serves as both an anti-apoptotic factor and a proliferative factor in leukemic cells. It potentially contributes to leukemogenesis through the NF-κB pathway in pediatric ALL patients

The tea plant CsLHT1 and CsLHT6 transporters take up amino acids, as a nitrogen source, from the soil of organic tea plantations

Organic tea is more popular than conventional tea that originates from fertilized plants. Amino acids inorganic soils constitute a substantial pool nitrogen (N) available for plants. However, the amino-acid contents in soils of tea plantations and how tea plants take up these amino acids remain largely unknown. In this study, we show that the amino-acid content in the soil of an organic tea plantation is significantly higher than that of a conventional tea plantation. Glutamate, alanine, valine, and leucine were the most abundant amino acids in the soil of this tea plantation. When 15N-glutamate was fed to tea plants, it was efficiently absorbed and significantly increased the contents of other amino acids in the roots. We cloned seven CsLHT genes encoding amino-acid transporters and found that the expression of CsLHT1, CsLHT2, and CsLHT6 in the roots significantly increased upon glutamate feeding. Moreover, the expression of CsLHT1 or CsLHT6 in a yeast amino-acid uptake-defective mutant, 22∆10α, enabled growth on media with amino acids constituting the sole N source. Amino-acid uptake assays indicated that CsLHT1 and CsLHT6 are H+-dependent high- and low-affinity amino-acid transporters, respectively. We further demonstrated that CsLHT1 and CsLHT6 are highly expressed in the roots and are localized to the plasma membrane. Moreover, overexpression of CsLHT1 and CsLHT6 in Arabidopsis significantly improved the uptake of exogenously supplied 15N-glutamate and 15N-glutamine. Taken together, our findings are consistent with the involvement of CsLHT1 and CsLHT6 in amino-acid uptake from the soil, which is particularly important for tea plants grown inorganic tea plantations

SKB1-mediated symmetric dimethylation of histone H4R3 controls flowering time in Arabidopsis

Plant flowering is a crucial developmental transition from the vegetative to reproductive phase and is properly timed by a number of intrinsic and environmental cues. Genetic studies have identified that chromatin modification influences the expression of FLOWERING LOCUS C (FLC), a MADS-box transcription factor that controls flowering time. Histone deacetylation and methylation at H3K9 and H3K27 are associated with repression of FLC; in contrast, methylation at H3K4 and H3K36 activates FLC expression. However, little is known about the functions of histone arginine methylation in plants. Here, we report that Arabidopsis Shk1 binding protein 1 (SKB1) catalyzes histone H4R3 symmetric dimethylation (H4R3sme2). SKB1 lesion results in upregulation of FLC and late flowering under both long and short days, but late flowering is reversed by vernalization and gibberellin treatments. An skb1-1flc-3 double mutant blocks late-flowering phenotype, which suggests that SKB1 promotes flowering by suppressing FLC transcription. SKB1 binds to the FLC promoter, and disruption of SKB1 results in reduced H4R3sme2, especially in the promoter of FLC chromatin. Thus, SKB1-mediated H4R3sme2 is a novel histone mark required for repression of FLC expression and flowering time control

Overexpression of RAN1 in Rice and Arabidopsis Alters Primordial Meristem, Mitotic Progress, and Sensitivity to Auxin

Ran is an evolutionarily conserved eukaryotic GTPase. We previously identified a cDNA of TaRAN1, a novel Ran GTPase homologous gene in wheat (Triticum aestivum) and demonstrated that TaRAN1 is associated with regulation of genome integrity and cell division in yeast (Saccharomyces cerevisiae) systems. However, much less is known about the function of RAN in plant development. To analyze the possible biological roles of Ran GTPase, we overexpressed TaRAN1 in transgenic Arabidopsis (Arabidopsis thaliana) and rice (Oryza sativa). TaRAN1 overexpression increased the proportion of cells in the G2 phase of the cell cycle, which resulted in an elevated mitotic index and prolonged life cycle. Furthermore, it led to increased primordial tissue, reduced number of lateral roots, and stimulated hypersensitivity to exogenous auxin. The results suggest that Ran protein was involved in the regulation of mitotic progress, either in the shoot apical meristem or the root meristem zone in plants, where auxin signaling is involved. This article determines the function of RAN in plant development mediated by the cell cycle and its novel role in meristem initiation mediated by auxin signaling

Histone H4R3 Methylation Catalyzed by SKB1/PRMT5 Is Required for Maintaining Shoot Apical Meristem

<div><p>The shoot apical meristem (SAM) is the source of all of the above-ground tissues and organs in post-embryonic development in higher plants. Studies have proven that the expression of genes constituting the WUSCHEL (WUS)-<i>CLAVATA</i> (<i>CLV</i>) feedback loop is critical for the SAM maintenance. Several histone lysine acetylation and methylation markers have been proven to regulate the transcription level of <i>WUS</i>. However, little is known about how histone arginine methylation regulates the expression of <i>WUS</i> and other genes. Here, we report that H4R3 symmetric dimethylation (H4R3sme2) mediated by SKB1/PRMT5 represses the expression of <i>CORYNE</i> (<i>CRN</i>) to maintain normal SAM geometrics. <i>SKB1</i> lesion results in small SAM size in <i>Arabidopsis</i>, as well as down-regulated expression of <i>WUS</i> and <i>CLV3</i>. Up-regulation of <i>WUS</i> expression enlarges SAM size in <i>skb1</i> mutant plants. We find that SKB1 and H4R3sme2 associate with the chromatin of the <i>CRN</i> locus to down-regulate its transcription. Mutation of <i>CRN</i> rescues the expression of <i>WUS</i> and the small SAM size of <i>skb1</i>. Thus, <i>SKB1</i> and <i>SKB1</i>-mediated H4R3sme2 are required for the maintenance of SAM in <i>Arabidopsis</i> seedlings.</p> </div

Loss of the golgin GM130 causes Golgi disruption, Purkinje neuron loss, and ataxia in mice

The Golgi apparatus lies at the heart of the secretory pathway where it is required for secretory trafficking and cargo modification. Disruption of Golgi architecture and function has been widely observed in neurodegenerative disease, but whether Golgi dysfunction is causal with regard to the neurodegenerative process, or is simply a manifestation of neuronal death, remains unclear. Here we report that targeted loss of the golgin GM130 leads to a profound neurological phenotype in mice. Global KO of mouse GM130 results in developmental delay, severe ataxia, and postnatal death. We further show that selective deletion of GM130 in neurons causes fragmentation and defective positioning of the Golgi apparatus, impaired secretory trafficking, and dendritic atrophy in Purkinje cells. These cellular defects manifest as reduced cerebellar size and Purkinje cell number, leading to ataxia. Purkinje cell loss and ataxia first appear during postnatal development but progressively worsen with age. Our data therefore indicate that targeted disruption of the mammalian Golgi apparatus and secretory traffic results in neuronal degeneration in vivo, supporting the view that Golgi dysfunction can play a causative role in neurodegeneration

CRN is a major target of SKB1 in regulating SAM size.

<div><p>(A) A diagram of the <i>CRN</i> gene structure, with bars representing the a-e regions examined by ChIP. The <i>CRN</i> open reading frame was shown by black boxes, while the exons of its neighbor genes (the left is At5G13300 and the right is At5G13280) were shown by white boxes.</p> <p>(B) The ChIP assay for <i>CRN</i> was performed with antibodies against SKB1 and H4R3sme2. Chromatin extracted from 12-day-old seedlings of Col-0 grown in soil, and <i>skb1</i> mutant chromatin as a control. Data represent triplicate quantitative real time PCR measurements of immunoprecipitated DNA, and the input represents chromatin before immunoprecipitation. Error bars represent relative SD of ChIP data.</p> <p>(C) Quantitative real-time-PCR analysis of the relative expression levels of <i>CRN</i> in Col-0, <i>skb1</i> and 35S<i>::</i>SKB1 <i>skb1</i> seedlings and normalized with ACTIN expression. Data represent the means ± SE of three independent experiments, <i>P</i> < 0.01.</p> <p>(D) and (E) Comparison of SAM size in Col-0, <i>skb1</i>, <i>crn</i>, and <i>crn </i><i>skb1</i> plants grown on MS medium to 9 DAG. Data in (E) represent the means ± SE (n≥11). Scale bar in (D) = 20 μm.</p> <p>(F) Staining results of GUS activity assays of pWUS<i>::GUS</i> and <i>pCLV3::GUS</i> transgenic lines in the Col-0, <i>skb1</i>, <i>crn</i>, and <i>crn </i><i>skb1</i> backgrounds, respectively. Materials used were seedlings grown to 9 DAG on MS medium. Scale bar = 20 μm.</p></div

Expression of miR-652-3p and Effect on Apoptosis and Drug Sensitivity in Pediatric Acute Lymphoblastic Leukemia

MicroRNAs (miRNAs) expression profiles were screened in plasma samples from pediatric patients with acute lymphoblastic leukemia (ALL) and healthy controls, using qRT-PCR-based TaqMan low-density miRNA arrays. MiR-652-3p (a circulating miRNA) was downregulated in new diagnosis (ND) patients compared with healthy controls. The levels of miR652-3p were restored in complete remission (CR) but were downregulated again in disease relapse (RE). The expression pattern of miR-652-3p was validated in bone marrow (BM) samples from other pediatric ALL patients. MiR-652-3p was significantly upregulated in BM when the patients (n=86) achieved CR, as compared with the matched ND samples (p<0.001). Moreover, the miR-652-3p levels in BM decreased again in two patients at RE. In addition, the lymphoblastic leukemia cell lines Reh and RS4:11 were found to have lower levels of miR-625-3p than the normal B-cell line. Overexpression of miR-652-3p using agomir increased the sensitivity to vincristine and cytarabine (all p<0.05) and promoted apoptosis (both p<0.05) in Reh and RS4:11 cells. In conclusion, the results suggested that a low level of miR-652-3p might be involved in the pathogenesis of pediatric ALL. Overexpression of miR-652-3p might suppress lymphoblastic leukemia cells, promoting apoptosis and increasing sensitivity to chemotherapeutic drugs