Nerve growth factor-dependent regulation of NADE-induced apoptosis

BEX1 and BEX4 Induce GBM Progression through Regulation of Actin Polymerization and Activation of YAP/TAZ Signaling

GBM is a high-grade cancer that originates from glial cells and has a poor prognosis. Although a combination of surgery, radiotherapy, and chemotherapy is prescribed to patients, GBM is highly resistant to therapies, and surviving cells show increased aggressiveness. In this study, we investigated the molecular mechanism underlying GBM progression after radiotherapy by establishing a GBM orthotopic xenograft mouse model. Based on transcriptomic analysis, we found that the expression of BEX1 and BEX4 was upregulated in GBM cells surviving radiotherapy. We also found that upregulated expression of BEX1 and BEX4 was involved in the formation of the filamentous cytoskeleton and altered mechanotransduction, which resulted in the activation of the YAP/TAZ signaling pathway. BEX1- and BEX4-mediated YAP/TAZ activation enhanced the tumor formation, growth, and radioresistance of GBM cells. Additionally, latrunculin B inhibited GBM progression after radiotherapy by suppressing actin polymerization in an orthotopic xenograft mouse model. Taken together, we suggest the involvement of cytoskeleton formation in radiation-induced GBM progression and latrunculin B as a GBM radiosensitizer.

Death domain of p75 neurotrophin receptor: a structural perspective on an intracellular signalling hub

The death domain (DD) is a globular protein motif with a signature feature of an all-helical Greek-key motif. It is a primary mediator of a variety of biological activities, including apoptosis, cell survival and cytoskeletal changes, which are related to many neurodegenerative diseases, neurotrauma, and cancers. DDs exist in a wide range of signalling proteins including p75 neurotrophin receptor (p75^NTR ), a member of the tumour necrosis factor receptor superfamily. The specific signalling mediated by p75^NTR in a given cell depends on the type of ligand engaging the extracellular domain and the recruitment of cytosolic interactors to the intracellular domain, especially the DD, of the receptor. In solution, the p75^NTR -DDs mainly form a symmetric non-covalent homodimer. In response to extracellular signals, conformational changes in the p75^NTR extracellular domain (ECD) propagate to the p75^NTR -DD through the disulfide-bonded transmembrane domain (TMD) and destabilize the p75^NTR -DD homodimer, leading to protomer separation and exposure of binding sites on the DD surface. In this review, we focus on recent advances in the study of the structural mechanism of p75^NTR -DD signalling through recruitment of diverse intracellular interactors for the regulation and control of diverse functional outputs.

Genome-wide gene expression analysis of amphioxus (Branchiostoma belcheri) following lipopolysaccharide challenge using strand-specific RNA-seq

Amphioxus is the closest living proxy for exploring the evolutionary origin of the immune system in vertebrates. To understand the immune responses of amphioxus to lipopolysaccharide (LPS), 5 ribosomal RNA (rRNA)-depleted libraries of amphioxus were constructed, including one control (0 h) library and 4 treatment libraries at 6, 12, 24, and 48 h post-injection (hpi) with LPS. The transcriptome of Branchiostoma belcheri was analyzed using strand-specific RNA sequencing technology (RNA-seq). A total of 6161, 6665, 7969, and 6447 differentially expressed genes (DEGs) were detected at 6, 12, 24, and 48 hpi, respectively, compared with expression levels at 0 h. We identified amphioxus genes active during the acute-phase response to LPS at different time points after stimulation. Moreover, to better visualize the resolution phase of the immune process during immune response, we identified 6057 and 5235 DEGs at 48 hpi by comparing with 6 and 24 hpi, respectively. Through real-time quantitative PCR (qRT-PCR) analysis of 12 selected DEGs, we demonstrated the accuracy of the RNA-seq data in this study. Functional enrichment analysis of DEGs demonstrated that most terms were related to defense and immune responses, disease and infection, cell apoptosis, and metabolism and catalysis. Subsequently, we identified 1330, 485, 670, 911, and 1624 time-specific genes (TSGs) at 0, 6, 12, 24, and 48 hpi. Time-specific terms at each of 5 time points were primarily involved in development, immune signaling, signal transduction, DNA repair and stability, and metabolism and catalysis, respectively. As this is the first study to report the transcriptome of an organism with primitive immunity following LPS challenge at multiple time points, it provides gene expression information for further research into the evolution of immunity in vertebrates.

Induction of Bex genes by curcumin is associated with apoptosis and activation of p53 in N2a neuroblastoma cells

Brain expressed X-linked (Bex) genes are newer group of pro-apoptotic genes. Role of any Bex gene in neuroblastoma and Bex4 and Bex6 in any cancer is completely unknown. Re-expression of all endogenous Bex genes by any nutraceutical is also unknown. Therefore, we investigated the induction of all endogenous Bex genes and associated mechanisms by curcumin using N2a, an aggressive neuroblastoma cell line. Curcumin induced all endogenous Bex genes prior to apoptosis in N2a cells in a dose- and time-dependent manner. Wortmannin (PI-3Kinases inhibitor), SP600125 (JNK inhibitor) and pifithrin-α (p53 inhibitor) abrogated curcumin-mediated induction of Bex genes. Inhibition of curcumin-mediated induction of Bex genes by pifithrin-α also inhibited N2a cells apoptosis suggesting, a direct role of Bex genes in N2a cells apoptosis and involvement of p53 in Bex genes induction. Curcumin treatment activated p53 through hyperphosphorylation at serine 15 before Bex genes induction indicating Bex genes are novel downstream targets of p53. Collectively, curcumin, a safe nutraceutical has the potential to induce all endogenous Bex genes to harness their anti-cancer properties in neuroblastoma cells. Re-expression of Bex genes by curcumin acts as tumor suppressors and may provide alternate strategy to treat neuroblastomas and other cancers with silenced Bex genes.

Recent advances in understanding neurotrophin signaling

The nerve growth factor family of growth factors, collectively known as neurotrophins, are evolutionarily ancient regulators with an enormous range of biological functions. Reflecting this long history and functional diversity, mechanisms for cellular responses to neurotrophins are exceptionally complex. Neurotrophins signal through p75 ^NTR, a member of the TNF receptor superfamily member, and through receptor tyrosine kinases (TrkA, TrkB, TrkC), often with opposite functional outcomes. The two classes of receptors are activated preferentially by proneurotrophins and mature processed neurotrophins, respectively. However, both receptor classes also possess neurotrophin-independent signaling functions. Signaling functions of p75 ^NTR and Trk receptors are each influenced by the other class of receptors. This review focuses on the mechanisms responsible for the functional interplay between the two neurotrophin receptor signaling systems.

Protective effects of matrine on experimental autoimmune encephalomyelitis via regulation of ProNGF and NGF signaling

Inflammation, demyelination, oligodendrocyte (OLG) death, and axonal degeneration are primary characteristics of multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE). OLGs generate myelin sheaths that surround axons, while damage to OLGs leads to demyelination and neurological functional deficit. Matrine (MAT), a quinolizidine alkaloid derived from the herb Radix Sophorae Flave, has been recently found to effectively ameliorate clinical signs in EAE. Its therapeutic mechanism has, however, not been completely elucidated. In the present study, we found that MAT retarded the disease process, attenuated the clinical severity of EAE rats, ameliorated inflammation and demyelination, and suppressed the apoptosis of OLGs in the central nervous system (CNS) of EAE rats. In addition, MAT markedly blocked increased expression of the proNGF-p75(NTR) death signaling complex, which is known to mediate OLG death in EAE animals. At the same time, MAT also prevented a decrease in the levels of NGF and its receptor TrkA, which together mediate the cell survival pathway and differentiation of OLGs. ProNGF, NGF, and the downstream effector proteins play an important role in the growth, differentiation, and apoptosis of OLGs as well as the reparative response to neuronal damage. These findings thus indicate that MAT improves clinical severity of EAE in part by reducing OLG apoptosis via restoring the ratios of proNGF:NGF and the respective receptors p75(NTR):TrkA in vivo. Taken together, these results suggest that MAT may be a promising agent for MS treatment based on its protective effect on OLGs.

Brain-Expressed X-linked (BEX) proteins in human cancers

The Brain-Expressed X-linked (BEX) family proteins are comprised of five human proteins including BEX1, BEX2, BEX3, BEX4 and BEX5. BEX family proteins are expressed in a wide range of tissues and are known to play a role in neuronal development. Recent studies suggest a role of BEX family proteins in cancers. BEX1 expression is lost in a subgroup of patients with acute myeloid leukemia (AML) and chronic myeloid leukemia (CML). Expression of BEX1 controls cell surface receptor signaling and restores imatinib response in resistant cells. BEX2 is overexpressed in a group of breast cancer patients and also in gliomas. Increased BEX2 expression led to enhanced NF-κB signaling as well as cell proliferation. Although BEX2 acts as tumor promoter in a subset of breast cancer, BEX3 expression displayed an opposite role. Overexpression of BEX3 resulted in inhibition of tumor formation in breast cancer mouse xenograft models. The role of BEX4 and BEX5 in cancer has not yet been defined. Collectively this suggests that BEX family members have distinct roles in cancers. While BEX1 and BEX3 act as tumor suppressors, BEX2 seems to act as an oncogene.

Biophysical Studies on BEX3, the p75NTR-Associated Cell Death Executor, Reveal a High-Order Oligomer with Partially Folded Regions

BEX3 (Brain Expressed X-linked protein 3) is a member of a mammal-specific placental protein family. Several studies have found the BEX proteins to be associated with neurodegeneration, the cell cycle and cancer. BEX3 has been predicted to be intrinsically disordered and also to represent an intracellular hub for cell signaling. The pro-apoptotic activity of BEX3 in association with a number of additional proteins has been widely supported; however, to the best of our knowledge, very limited data are available on the conformation of any of the members of the BEX family. In this study, we structurally characterized BEX3 using biophysical experimental data. Small angle X-ray scattering and atomic force microscopy revealed that BEX3 forms a specific higher-order oligomer that is consistent with a globular molecule. Solution nuclear magnetic resonance, partial proteinase K digestion, circular dichroism spectroscopy, and fluorescence techniques that were performed on the recombinant protein indicated that the structure of BEX3 is composed of approximately 31% α-helix and 20% β-strand, contains partially folded regions near the N- and C-termini, and a core which is proteolysis-resistant around residues 55-120. The self-oligomerization of BEX3 has been previously reported in cell culture and is consistent with our in vitro data.

Bex2 controls proliferation of human glioblastoma cells through NF-κB signaling pathway

Glioblastoma is the most common and fatal human brain malignancy in adults with highly proliferative capacity. Despite advances in surgery and adjuvant therapy, the median survival of patients has changed little over recent decades. Identifying molecules critical for glioma development is significant for devising effective targeted therapy. We previously reported that Bex2, a member of the brain expressed X-linked gene family, promoted the progression of glioma by promoting cell proliferation. In the present study, we investigated the main mechanism of Bex2 promoting the proliferation of glioblastoma cells. We found that Bex2 downregulation inhibited glioma cell proliferation and the expression of NF-κB p65, but Bex2 overexpression promoted them. Similarly, the proliferation of glioma cells was inhibited by p65 downregulation but increased by p65 overexpression. In addition, Bex2 overexpression-induced cell proliferation was abolished by p65 downregulation. Furthermore, Bex2 with nuclear localization signal deleted no longer promoted p65 expression. In conclusion, this study demonstrates that Bex2 promotes proliferation of human glioblastoma cells via NF-κB signaling pathway and Bex2 nuclear location is critical for p65 expression.

Dysregulation of astrocyte-motoneuron cross-talk in mutant superoxide dismutase 1-related amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis is a neurodegenerative disease in which death of motoneurons leads to progressive failure of the neuromuscular system resulting in death frequently within 2-3 years of symptom onset. Focal onset and propagation of the disease symptoms to contiguous motoneuron groups is a striking feature of the human disease progression. Recent work, using mutant superoxide dismutase 1 murine models and in vitro culture systems has indicated that astrocytes are likely to contribute to the propagation of motoneuron injury and disease progression. However, the basis of this astrocyte toxicity and/or failure of motoneuron support has remained uncertain. Using a combination of in vivo and in vitro model systems of superoxide dismutase 1-related amyotrophic lateral sclerosis, linked back to human biosamples, we set out to elucidate how astrocyte properties change in the presence of mutant superoxide dismutase 1 to contribute to motoneuron injury. Gene expression profiling of spinal cord astrocytes from presymptomatic transgenic mice expressing mutant superoxide dismutase 1 revealed two striking changes. First, there was evidence of metabolic dysregulation and, in particular, impairment of the astrocyte lactate efflux transporter, with resultant decrease of spinal cord lactate levels. Second, there was evidence of increased nerve growth factor production and dysregulation of the ratio of pro-nerve growth factor to mature nerve growth factor, favouring p75 receptor expression and activation by neighbouring motoneurons. Functional in vitro studies showed that astrocytes expressing mutant superoxide dismutase 1 are toxic to normal motoneurons. We provide evidence that reduced metabolic support from lactate release and activation of pro-nerve growth factor-p75 receptor signalling are key components of this toxicity. Preservation of motoneuron viability could be achieved by increasing lactate provision to motoneurons, depletion of increased pro-nerve growth factor levels or p75 receptor blockade. These findings are likely to be relevant to human amyotrophic lateral sclerosis, where we have demonstrated increased levels of pro-nerve growth factor in cerebrospinal fluid and increased expression of the p75 receptor by spinal motoneurons. Taken together, these data confirm that altered properties of astrocytes are likely to play a crucial role in the propagation of motoneuron injury in superoxide dismutase 1-related amyotrophic lateral sclerosis and indicate that manipulation of the energy supply to motoneurons as well as inhibition of p75 receptor signalling may represent valuable neuroprotective strategies.

TrkA overexpression enhances growth and metastasis of breast cancer cells

The Trk family of neurotrophin tyrosine kinase receptors is emerging as an important player in carcinogenic progression in non-neuronal tissues. Here, we show that breast tumors present high levels of TrkA and phospho-TrkA compared to normal breast tissues. To further evaluate the precise functions of TrkA overexpression in breast cancer development, we have performed a series of biological tests using breast cancer cells that stably overexpress TrkA. We show that (1) TrkA overexpression promoted cell growth, migration and invasion in vitro; (2) overexpression of TrkA per se conferred constitutive activation of its tyrosine kinase activity; (3) signal pathways including PI3K-Akt and ERK/p38 MAP kinases were activated by TrkA overexpression and were required for the maintenance of a more aggressive cellular phenotype; and (4) TrkA overexpression enhanced tumor growth, angiogenesis and metastasis of xenografted breast cancer cells in immunodeficient mice. Moreover, recovered metastatic cells from the lungs exhibited enhanced anoikis resistance that was abolished by the pharmacological inhibitor K252a, suggesting that TrkA-promoted breast tumor metastasis could be mediated at least in part by enhancing anoikis resistance. Together, these results provide the first direct evidence that TrkA overexpression enhances the tumorigenic properties of breast cancer cells and point to TrkA as a potential target in breast cancer therapy.

Adaptive evolution and frequent gene conversion in the brain expressed X-linked gene family in mammals

This work examines the molecular evolution of a brain-expressed X-linked gene family in the mammalian genomes of human, chimp, macaque, mouse, rat, dog, and cow. The gene structures are well conserved across family members and among the mammals in that all five members have three exons with the first two exons untranslated. Furthermore, the five members are arranged tandemly on chromosome X with Bex5, Bex1, Bex2 on the negative strand and Bex4, Bex3 on the positive strand, and this physical arrangement remains conserved among species. Sequence analyses indicate that gene conversion has been frequent and ongoing among Bex1-4, occurring in multiple species independently. All gene conversions in different species between Bex1 and Bex4, and between Bex2 and Bex3, appear to be limited to the upstream regions of the third exon, whereas the gene conversions occurred independently in different species between Bex1 and Bex2 and cover only the third exon. Bex5 appears to have little exchange of genetic information with other members, possibly due to its distance from other members. The GC content decreases from 5'-UTR, intron 1, intron 2, coding region, to 3'-UTR, reflecting faithfully the frequency of gene conversion in different regions of the Bex genes. Sequence analyses also suggest that both relaxed selective constraint and positive selection have acted on the Bex members after duplication. In particular, Bex3 shows strong evidence of positive selection and seems to have evolved a new gene function after gene duplication.

BEX2 is overexpressed in a subset of primary breast cancers and mediates nerve growth factor/nuclear factor-kappaB inhibition of apoptosis in breast cancer cell lines

We have identified a novel subtype of estrogen receptor (ER)-positive breast cancers with improved outcome after tamoxifen treatment and characterized by overexpression of the gene BEX2. BEX2 and its homologue BEX1 have highly correlated expression and are part of a cluster enriched for ER response and apoptosis genes. BEX2 expression is induced after estradiol (E2) treatment with a peak at 3 h, suggesting BEX2 is an estrogen-regulated gene. BEX2 belongs to a family of genes, including BEX1, NGFRAP1 (alias BEX3), BEXL1 (alias BEX4), and NGFRAP1L1 (alias BEX5). Both BEX1 and NGFRAP1 interact with p75NTR and modulate nerve growth factor (NGF) signaling through nuclear factor-kappaB (NF-kappaB) to regulate cell cycle, apoptosis, and differentiation in neural tissues. In breast cancer cells, NGF inhibits C2-induced apoptosis through binding of p75NTR and NF-kappaB activation. Here, we show that BEX2 expression is necessary and sufficient for the NGF-mediated inhibition (through NF-kappaB activation) of C2-induced apoptosis. We also show that BEX2 modulates apoptosis of breast cancer cells in response to E2 (50 nmol/L) and tamoxifen (5 and 10 micromol/L). Furthermore, BEX2 overexpression enhances the antiproliferative effect of tamoxifen at pharmacologic dose (1 micromol/L). These data suggest that a NGF/BEX2/NF-kappaB pathway is involved in regulating apoptosis in breast cancer cells and in modulating response to tamoxifen in primary tumors.

Rex3 (reduced in expression 3) as a new tumor marker in mouse hepatocarcinogenesis

In a previous microarray expression analysis, Rex3, a gene formerly not linked to tumor formation, was found to be highly overexpressed in both Ctnnb1-(beta-Catenin) and Ha-ras-mutated mouse liver tumors. Subsequent analyses by in situ hybridization and real-time PCR confirmed a general liver tumor-specific overexpression of the gene (up to 400-fold). To investigate the role of Rex3 in liver tumors, hepatoma cells were transfected with FLAG- and Myc-tagged Rex3 expression vectors. Rex3 was shown to be exclusively localized to the cytoplasm, as determined by fluorescence microscopy and Western blotting. However, forced overexpression of Rex3 did not significantly affect proliferation or stress-induced apoptosis of transfected mouse hepatoma cells. Rex3 mRNA was determined in primary hepatocytes in culture by real-time PCR. In primary mouse hepatocytes, expression of Rex3 increased while cells dedifferentiated in culture. This effect was abolished when hepatocytes were maintained in a differentiated state. Furthermore, expression of Rex3 decreased in mouse liver with age of mice and the expression profile was highly correlated to that of the tumor markers alpha-fetoprotein and H19. The findings suggest a role of Rex3 as a marker for hepatocyte differentiation/dedifferentiation processes and tumor formation.

The p75(NTR) tumor suppressor induces cell cycle arrest facilitating caspase mediated apoptosis in prostate tumor cells

The p75 neurotrophin receptor (p75(NTR)) is a death receptor which belongs to the tumor necrosis factor receptor super-family of membrane proteins. This study shows that p75(NTR) retarded cell cycle progression by induced accumulation of cells in G0/G1 and a reduction in the S phase of the cell cycle. The rescue of tumor cells from cell cycle progression by a death domain deleted (DeltaDD) dominant-negative antagonist of p75(NTR) showed that the death domain transduced anti-proliferative activity in a ligand-independent manner. Conversely, addition of NGF ligand rescued retardation of cell cycle progression with commensurate changes in components of the cyclin/cdk holoenzyme complex. In the absence of ligand, p75(NTR)-dependent cell cycle arrest facilitated an increase in apoptotic nuclear fragmentation of the prostate cancer cells. Apoptosis of p75(NTR) expressing cells occurred via the intrinsic mitochondrial pathway leading to a sequential caspase-9 and -7 cascade. Since the death domain deleted dominant-negative antagonist of p75(NTR) rescued intrinsic caspase associated apoptosis in PC-3 cells, this shows p75(NTR) was integral to ligand independent induction of apoptosis. Moreover, the ability of ligand to ameliorate the p75(NTR)-dependent intrinsic apoptotic cascade indicates that NGF functioned as a survival factor for p75(NTR) expressing prostate cancer cells.

Human Bex2 interacts with LMO2 and regulates the transcriptional activity of a novel DNA-binding complex

Human Bex2 (brain expressed X-linked, hBex2) is highly expressed in the embryonic brain, but its function remains unknown. We have identified that LMO2, a LIM-domain containing transcriptional factor, specifically interacts with hBex2 but not with mouse Bex1 and Bex2. The interaction was confirmed both by pull-down with GST-hBex2 and by coimmunoprecipitation assays in vivo. Using electrophoretic mobility shift assay, we have demonstrated the physical interaction of hBex2 and LMO2 as part of a DNA-binding protein complex. We have also shown that hBex2 can enhance the transcriptional activity of LMO2 in vivo. Furthermore, using mammalian two-hybrid analysis, we have identified a neuronal bHLH protein, NSCL2, as a novel binding partner for LMO2. We then showed that LMO2 could up-regulate NSCL2-dependent transcriptional activity, and hBex2 augmented this effect. Thus, hBex2 may act as a specific regulator during embryonic development by modulating the transcriptional activity of a novel E-box sequence-binding complex that contains hBex2, LMO2, NSCL2 and LDB1.

Characterization of the Bex gene family in humans, mice, and rats

To better understand the development of ventral mesencephalic dopamine neurons, we performed subtractive hybridization screens to find ventral mesencephalic genes expressed at rat embryonic day 10 when these neurons begin to differentiate. The most commonly identified genes in these screens were members of the Bex (Brain expressed X-linked) gene family, rat Bex1 (Rex3), and a novel gene, rat Bex4. After identifying these genes, we then sought to characterize the Bex gene family. Two additional novel Bex genes (human Bex5 and mouse Bex6) were discovered through genomic databases. Bex5 is present in humans and monkeys, but not rodents, while Bex6 exists in mice, but not humans. Bex4 and Bex5 are localized to the X chromosome, are expressed in brain, and are similar in sequence. Bex4 and Bex5 are 54% and 56% identical to human Bex3 (pHGR74, NADE). Mouse Bex6 is on chromosome 16 and is 67% identical to mouse Bex4. Human Bex gene expression was studied with tissue expression arrays probed with specific oligonucleotides. Human Bex1 and Bex2 have similar expression patterns in the central nervous system with high levels in pituitary, cerebellum, and temporal lobe, and Bex1 is widely expressed outside of the central nervous system with high expression in the liver. Human Bex4 is highly expressed in heart, skeletal muscle, and liver, while Bex3 and Bex5 are more widely expressed. The subcellular localization of the Bex proteins varies from nuclear (rat Bex1) to cytoplasmic (rat Bex3, human Bex5, and mouse Bex6) and to both nuclear and cytoplasmic (rat Bex2 and rat Bex4). Rat Bex3, rat Bex4, human Bex5, and mouse Bex6 are degraded by the proteasome, while rat Bex1 or Bex2 are not. Rat Bex3 protein can likely bind transition metals through a histidine-rich domain. Because this gene family was originally named Bex and because these genes are unified by sequence similarity and gene structure, we believe the Bex nomenclature should prevail over nomenclature based on function (NADE) that has not been extended to the other Bex genes. We conclude that the Bex gene family members are highly homologous but differ in their expression patterns, subcellular localization, and degradation by the proteasome.

Up-regulated genes in diethylnitrosamine-induced liver cancer in rats

AIM: To investigate the differentially expressed genes in rat liver cancer induced by diethylnitrosamine (DEN), and to explore mechanism in DEN-induced carcinogenesis.

METHODS: The model of liver cancer was induced by DEN. The RNA was extracted purified from the cancer cells with routine methods. Affymetrix Rat 230A GeneChip and technique were used to detect the dis-crepancies of gene expression between tissues of nor-mal control and liver cancer.

RESULTS: Of 15710 genes in the GeneChip, the positive expression covered a percentage of 84.54% in liver cancer. There were 509 genes whose expression levels in liver cancer were about 5 times as high as those in the normal controls, of which 325 were EST fragments. Of the 325 genes, 184 ones were with known function, of which 168 had been reported in relevant references. Of the 168 genes, 100 ones were associated with the tumor (36 with liver cancer), 4 with liver, and the other 64 had no relation with tumor and liver.

CONCLUSION: DEN-induced up-regulations of genes in liver cancer are fairly complicated, of which 168 ones need paying more attention to.

Immunolocalization of Bex protein in the mouse brain and olfactory system

Bex proteins are expressed from a family of "brain expressed X-linked genes" that are closely linked on the X-chromosome. Bex1 and 2 have been characterized as interacting partners of the olfactory marker protein (OMP). Here we report the distribution of Bex1 and Bex2 mRNAs in several brain regions and the development and characterization of an antibody to mouse Bex1 protein that cross-reacts with Bex2 (but not Bex3), and its use to determine the cellular distribution of Bex proteins in the murine brain. The specificity of the antiserum was characterized by immunoprecipitation and Western blots of tissue and transfected cell extracts and by immunocytochemical analyses of cells transfected with either Bex1 or Bex2. Antibodies preabsorbed with Bex2 still recognize Bex1, while blocking with Bex1 eliminates all immunoreactivity to both Bex1 and Bex2. Bex immunoreactivity (ir) was primarily localized to neuronal cells within several regions of the brain, including the olfactory epithelium, bulb, peri/paraventricular nuclei, suprachiasmatic nucleus, arcuate nucleus, median eminence, lateral hypothalamic area, thalamus, hippocampus, and cerebellum. RT-PCR and in situ hybridization demonstrated the presence of Bex mRNA in several of these regions. Double-label immunocytochemistry indicates that Bex-ir is colocalized with OMP in mature olfactory receptor neurons (ORNs) and in the OMP-positive subpopulation of neurons in hypothalamus. This is the first anatomical mapping of Bex proteins in the mouse brain and their colocalization with OMP in ORNs and hypothalamus.

UV induced bystander signaling leading to apoptosis

Human keratinocytes (HaCaT) were exposed to UV (A+B) (UVA-350-400 mJ/cm2 and UVB-30 mJ/cm2) which induces apoptosis as evidenced by MTT assay, DNA laddering, Bax and Fas up-regulation. UV induced apoptotic conditioned media (6 h or earlier) did not cause apoptosis in unexposed cells. However, treatment with conditioned medium collected post UV exposure (1 h) induced Bax in unexposed cells as observed by RT-PCR. The induction of cell death was initiated by conditioned medium collected 12 h after UV exposure and the extent of death was increased progressively when conditioned medium collected 24 or 72 h post UV exposure was used. Medium collected 24 h after UV exposure also increased mitochondrial membrane permeability as determined by rhodamine uptake. Conditioned medium induced apoptosis did not involve reactive oxygen species (ROS) unlike UV induced apoptosis indicating that the apoptosis pathway could be different. Interestingly, at high dilution apototic conditioned medium did not induce apoptosis but actually protected cells from UV insult. The role of nerve growth factor (NGF) in UV induced bystander effects are also discussed.

Global analysis of genes differentially expressed in branching and non-branching regions of the mouse embryonic lung

During development, the proximal and distal regions of respiratory tract undergo distinct processes that ultimately give rise to conducting airways and alveoli. To gain insights into the genetic pathways differentially activated in these regions when branching morphogenesis is initiating, we characterized their transcriptional profiles in murine rudiments isolated at embryonic (E) day 11.5. By using oligonucleotide microarrays, we identified 83 and 128 genes preferentially expressed in branching and non-branching regions, respectively. The majority of these genes (85%) had not been previously described in the lung, or in other organs. We report restricted expression patterns of 22 of these genes were by in situ hybridization. Among them in the lung potential components of the Wnt, TGF beta, FGF and retinoid pathways identified in other systems, and uncharacterized genes, such as translocases, small GTPases and splicing factors. In addition, we provide a more detailed analysis of the expression pattern and regulation of a representative gene from the distal (transforming growth factor, beta induced) and proximal (WW domain-containing protein 2) regions. Our data suggest that these genes may regulate focal developmental events specific of each of these regions during respiratory tract formation.