Up-regulation of hexokinaseII in myeloma cells: targeting myeloma cells with 3-bromopyruvate

Hexokinase II (HKII), a key enzyme of glycolysis, is widely over-expressed in cancer cells. However, HKII levels and its roles in ATP production and ATP-dependent cellular process have not been well studied in hematopoietic malignant cells including multiple myeloma (MM) cells.We demonstrate herein that HKII is constitutively over-expressed in MM cells. 3-bromopyruvate (3BrPA), an inhibitor of HKII, promptly and substantially suppresses ATP production and induces cell death in MM cells. Interestingly, cocultures with osteoclasts (OCs) but not bone marrow stromal cells (BMSCs) enhanced the phosphorylation of Akt along with an increase in HKII levels and lactate production in MM cells. The enhancement of HKII levels and lactate production in MM cells by OCs were mostly abrogated by the PI3K inhibitor LY294002, suggesting activation of glycolysis in MM cells by OCs via the PI3K-Akt-HKII pathway. Although BMSCs and OCs stimulate MM cell growth and survival, 3BrPA induces cell death in MM cells even in cocultures with OCs as well as BMSCs. Furthermore, 3BrPA was able to diminish ATP-dependent ABC transporter activity to restore drug retention in MM cells in the presence of OCs. These results may underpin possible clinical application of 3BrPA in patients with MM.     

T cell receptor-mediated signaling induces GRP78 expression in T cells: the implications in maintaining T cell viability

The 78-kDa glucose-regulated protein (GRP78) is an important molecular chaperone in the endoplasmic reticulum (ER) induced by various stresses. This study showed that stimulation with anti-CD3 mAb, PMA plus ionomycin, or an antigen increased the levels of GRP78 mRNA in primary T cells, which was inhibited by Ca²⁺ chelators EGTA and BAPTA-AM and by an inhibitor of calcineurin FK506. In addition, the specific knockdown of GRP78 protein expression induced apoptosis in mouse EL-4 T cell line associated with CHOP induction and caspase-3 activation. Furthermore, overexpression of GRP78 inhibited PMA/ionomycin-induced cell death in EL-4 cells. Collectively, GRP78 expression is induced by TCR activation via a Ca²⁺-dependent pathway and may play a critical role in maintaining T cell viability in the steady and TCR-activated states. These results suggest a novel regulatory mechanism and an essential function of GRP78 in T cells.     

Small RNAs in tomato fruit and leaf development

Tomato fruit and leaf development offers excellent systems to study the evolution of gene regulation underlying development of different organs. We have identified over 350 and 700 small RNAs from tomato fruit and leaf, respectively. Except for conserved microRNAs, more than 90% of the small RNAs are unique to tomato. We confirmed expression of some conserved as well as novel putative microRNAs by Northern hybridization. Our results help form a basis for comparative studies on how small RNA-mediated gene expression has contributed to the evolution of common and distinct developmental pathways of fruits and leaves. We have established a website (http://ted.bti.cornell.edu/digital/sRNA/) for public access to all of our small RNA sequences, their expression patterns in respective tissues, and their matching genes or predicted target genes in a searchable manner.     

AcrS/EnvR represses expression of the acrAB multidrug efflux genes in Escherichia coli

The acrS regulatory gene is located upstream of the acrEF multidrug efflux system genes. However, the roles of AcrS in regulation of drug efflux pumps have not been clearly understood. Here we show that AcrS represses other multidrug efflux genes, acrAB, which encode a major efflux system in Escherichia coli.     

Alkane inducible proteins in Geobacillus thermoleovorans B23

Background  

Initial step of β-oxidation is catalyzed by acyl-CoA dehydrogenase in prokaryotes and mitochondria, while acyl-CoA oxidase primarily functions in the peroxisomes of eukaryotes. Oxidase reaction accompanies emission of toxic by-product reactive oxygen molecules including superoxide anion, and superoxide dismutase and catalase activities are essential to detoxify them in the peroxisomes. Although there is an argument about whether primitive life was born and evolved under high temperature conditions, thermophilic archaea apparently share living systems with both bacteria and eukaryotes. We hypothesized that alkane degradation pathways in thermophilic microorganisms could be premature and useful to understand their evolution.     

Cellular basis of developmental plasticity observed in heterophyllous leaf formation of Ludwigia arcuata (Onagraceae)

When heterophyllous plants of Ludwigia arcuata Walt. (Onagraceae) were transferred from aerial condition to submergence, young developing leaves were matured into leaves with intermediate shape between aerial-type and submerged-type, showing spatulate shape (spoon-shaped). This change was also induced by the exposure of plants to ethylene. On the other hand, when the plants were transferred from submergence to aerial conditions, young developing leaves were matured into intermediate-type leaves with elliptic shape (spearhead shape). Anatomical analysis revealed that the formation of spatulate leaf was caused by the reduction of the number of epidermal cells aligned in the leaf transverse direction in the basal region of the leaf while the tip regions remained as before and did not respond to this treatment. During development, the ethylene-induced spatulate leaves showed that three types of alterations in epidermal cell division were involved in this process. Changes in the distribution of cell divisions in leaf lamina were detected by the first day of ethylene exposure, and changes in the orientation of cell division planes were detected by the second day. However, changes in the number of cells aligned in the leaf transverse direction were not detected by this time. Three days after ethylene exposure, frequency of cell divisions changed, and by the time changes of cell numbers aligned in the leaf transverse direction were observed. Thus, the formation of intermediate-type leaves in L. arcuata was ascribed to the alterations of cell division patterns which was induced by ethylene.     

Analysis of cis-regulatory elements controlling spatio-temporal expression of T-brain gene in sea urchin, Hemicentrotus pulcherrimus

In sea urchin development, micromere descendants play important roles in skeletogenesis and induction of gastrulation. We previously reported that the T-brain homolog of sea urchin Hemicentrotus pulcherrimus, HpTb expresses specifically in micromere descendants and is required for induction of gastrulation and skeletogenesis. Thus, HpTb is thought to play important roles in the function of micromere-lineage cells. To identify cis-regulatory regions responsible for spatio-temporal gene expression of HpTb, we isolated approximately 7kb genomic region of HpTb gene and showed that GFP expression driven by this region exhibits the spatio-temporal pattern corresponding substantially to that of endogenous HpTb expression. Deletion of interspecifically conserved C2 and C4 regions resulted in an increase of ectopic expression. Mutations in Hairy family and Snail family consensus sequences in C1 and C2 regions also increased ectopic expression. Furthermore, we demonstrated that C4 region functions as enhancer, and that three Ets family consensus sequences are involved in this activity but not in spatial regulation. Therefore, we concluded that expression of HpTb gene is regulated by multiple cis-regulatory elements.     

Ecotype-specific and chromosome-specific expansion of variant centromeric satellites in <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis>

Despite the conserved roles and conserved protein machineries of centromeres, their nucleotide sequences can be highly diverse even among related species. The diversity reflects rapid evolution, but the underlying mechanism is largely unknown. One approach to monitor rapid evolution is examination of intra-specific variation. Here we report variant centromeric satellites of Arabidopsis thaliana found through survey of 103 natural accessions (ecotypes). Among them, a cluster of variant centromeric satellites was detected in one ecotype, Cape Verde Islands (Cvi). Recombinant inbred mapping revealed that the variant satellites are distributed in centromeric region of the chromosome 5 (CEN5) of this ecotype. This apparently recent variant accumulation is associated with large deletion of a pericentromeric region and the expansion of satellite region. The variant satellite was bound to HTR12 (centromeric variant histone H3), although expansion of the satellite was not associated with comparable increase in the HTR12 binding. The results suggest that variant satellites with centromere function can rapidly accumulate in one centromere, supporting the model that the satellite repeats in the array are homogenized by occasional unequal crossing-over, which has a potential to generate an expansion of local sequence variants within a centromere cluster. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.