Mutations of the homeobox genes Dlx-1 and Dlx-2 disrupt the striatal subventricular zone and differentiation of late born striatal neurons

The striatum has a central role in many neurobiological processes, yet little is known about the molecular control of its development. Inroads to this subject have been made, due to the discovery of transcription factors, such as the Dlx genes, whose expression patterns suggest that they have a role in striatal development. We report that mice lacking both Dlx-1 and Dlx-2 have a time-dependent block in striatal differentiation. In these mutants, early born neurons migrate into a striatum-like region, which is enriched for markers of the striosome (patch) compartment. However, later born neurons accumulate within the proliferative zone. Several lines of evidence suggest that mutations in Dlx-1 and Dlx-2 produce abnormalities in the development of the striatal subventricular zone and in the differentiation of striatal matrix neurons.

Role of the Dlx homeobox genes in proximodistal patterning of the branchial arches: mutations of Dlx-1, Dlx-2, and Dlx-1 and -2 alter morphogenesis of proximal skeletal and soft tissue structures derived from the first and second arches

The Dlx homeobox gene family is expressed in a complex pattern within the embryonic craniofacial ectoderm and ectomesenchyme. A previous study established that Dlx-2 is essential for development of proximal regions of the murine first and second branchial arches. Here we describe the craniofacial phenotype of mice with mutations in Dlx-1 and Dlx-1 and -2. The skeletal and soft tissue analyses of mice with Dlx-1 and Dlx-1 and -2 mutations provide additional evidence that the Dlx genes regulate proximodistal patterning of the branchial arches. This analysis also elucidates distinct and overlapping roles for Dlx-1 and Dlx-2 in craniofacial development. Furthermore, mice lacking both Dlx-1 and -2 have unique abnormalities, including the absence of maxillary molars. Dlx-1 and -2 are expressed in the proximal and distal first and second arches, yet only the proximal regions are abnormal. The nested expression patterns of Dlx-1, -2, -3, -5, and -6 provide evidence for a model that predicts the region-specific requirements for each gene. Finally, the Dlx-2 and Dlx-1 and -2 mutants have ectopic skull components that resemble bones and cartilages found in phylogenetically more primitive vertebrates.

Null mutation of Dlx-2 results in abnormal morphogenesis of proximal first and second branchial arch derivatives and abnormal differentiation in the forebrain

Genetic analysis of the development and evolution of the vertebrate head is at a primitive stage. Many homeo box genes, including the Distal-less family, are potential regulators of head development. To determine the function of Dlx-2, we generated a null mutation in mice using gene targeting. In homozygous mutants, differentiation within the forebrain is abnormal and the fate of a subset of cranial neural crest cells is respecified. The latter causes abnormal morphogenesis of the skeletal elements derived from the proximal parts of the first and second branchial arches. We hypothesize that the affected skull bones from the first arch have undergone a transformation into structures similar to those found in reptiles. These results show that Dlx-2 controls development of the branchial arches and the forebrain and suggests its role in craniofacial evolution.

Control of oligodendrocyte differentiation by the Nkx2.2 homeodomain transcription factor

Oligodendrocytes are derived from glial precursors that arise from the ventral neural tube early in development. In the developing chicken CNS, oligodendrocyte progenitors selectively express Nkx2.2 homeodomain transcription factor, raising the possibility that Nkx2.2 may directly regulate oligogliogenesis. In this study, we have examined Nkx2.2 expression in rodent glial precursors and studied the effect of a loss of Nkx2.2 on oligodendrocyte and astrocyte differentiation. We show that Nkx2.2 is also expressed in mammalian oligodendrocyte progenitors and that the differentiation of MBP-positive and PLP-DM20-positive oligodendrocytes is dramatically retarded in Nkx2.2-null mutants along the entire rostrocaudal axis. In contrast, no effect is seen on astrocytic differentiation. Interestingly, absence of Nkx2.2 expression leads to a ventral expansion of the Olig1/Olig2 expression in neuroepithelial cells into the Nkx2.2 domain and a consequent increase in the production of Olig1/Olig2-positive and platelet-derived growth factor receptor α-positive oligodendrocyte progenitors. These results strongly suggest that Nkx2.2 regulates the differentiation and/or maturation, but not the initial specification, of oligodendrocyte progenitors. Consistent with this suggestion, overproduction of Nkx2.2 protein in fibroblast cells can induce gene expression from the proteolipid protein promoter.

Increased production of reactive oxygen species contributes to motor neuron death in a compression mouse model of spinal cord injury

STUDY DESIGN

Experimental laboratory investigation of the role and pathways of reactive oxygen species (ROS)-mediated motor neuron cell death in a mouse model of compression spinal cord injury.

OBJECTIVES

To analyze ROS-mediated oxidative stress propagation and signal transduction leading to motor neuron apoptosis induced by compression spinal cord injury.

SETTING

University of Louisville Health Science Center.

METHODS

Adult C57BL/6J mice and transgenic mice overexpressing SOD1 were severely lesioned at the lumbar region by compression spinal cord injury approach. Fluorescent oxidation, oxidative response gene expression and oxidative stress damage markers were used to assay spinal cord injury-mediated ROS generation and oxidative stress propagation. Biochemical and immunohistochemical analyses were applied to define the ROS-mediated motor neuron apoptosis resulted from compression spinal cord injury.

RESULTS

ROS production was shown to be elevated in the lesioned spinal cord as detected by fluorescent oxidation assays. The early oxidative stress response markers, NF-kappaB transcriptional activation and c-Fos gene expression, were significantly increased after spinal cord injury. Lipid peroxidation and nucleic acid oxidation were also elevated in the lesioned spinal cord and motor neurons. Cytochrome c release, caspase-3 activation and apoptotic cell death were increased in the spinal cord motor neuron cells after spinal cord injury. On the other hand, transgenic mice overexpressing SOD1 showed lower levels of steady-state ROS production and reduction of motor neuron apoptosis compared to that of control mice after spinal cord injury.

CONCLUSION

These data together provide direct evidence to demonstrate that the increased production of ROS is an early and likely causal event that contributes to the spinal cord motor neuron death following spinal cord injury. Thus, antioxidants/antioxidant enzyme intervention combined with other therapy may provide an effective approach to alleviate spinal cord injury-induced motor neuron damage and motor dysfunction.

Control of anteroposterior and dorsoventral domains of Nkx-6.1 gene expression relative to other Nkx genes during vertebrate CNS development

Here we report the isolation, sequence and developmental expression in the central nervous system of several members of the chicken and mouse Nkx gene family. These are among the earliest genes to be regionally expressed in the neural plate; they are expressed just above the axial mesendoderm (prechordal mesendoderm and notochord). Each Nkx gene has a distinct spatial pattern of expression along the anterior-posterior axis of the ventral central nervous system: Nkx-2. 2 is expressed along the entire axis, whereas Nkx-2.1 is restricted to the forebrain, and Nkx-6.1 and Nkx-6.2 are largely excluded from the forebrain. They are also expressed in distinct patterns along the dorsal-ventral axis. These genes are expressed in both the ventricular and mantle zones; in the mantle zone Nkx-6.1 is co-expressed with Islet-1 in a subset of motor neurons. Like other Nkx genes, expression of Nkx-6.1 is induced by the axial mesendoderm and by sonic hedgehog protein. BMP-7 represses Nkx-6.1 expression. While the notochord can induce Nkx-6.1 expression in the anterior neural plate, sonic hedgehog protein does not, suggesting that the notochord produces additional molecules that can regulate ventral patterning.

CYP4A in tumor-associated macrophages promotes pre-metastatic niche formation and metastasis

Tumor-associated macrophages (TAMs) play an essential role in metastasis. However, what enables TAMs to have a superior capacity to establish pre-metastatic microenvironment in distant organs is unclear. Here we have begun to uncover the effects of cytochrome P450 (CYP) 4A in TAMs on lung pre-metastatic niche formation and metastasis. CYP4A⁺ TAM infiltration was positively associated with metastasis, pre-metastatic niche formation and poor prognosis in breast cancer patients. The pharmacological inhibition of CYP4A reduced lung pre-metastatic niche formation (evidenced by a decrease in vascular endothelial growth factor receptor 1 positive (VEGFR1⁺) myeloid cell recruitment and pro-metastatic protein expression) and metastatic burden, accompanied with TAM polarization away from the M2 phenotype in spontaneous metastasis models of 4T1 breast cancer and B16F10 melanoma. Co-implantation of 4T1 cells with CYP4A10^high macrophages promoted lung pre-metastatic niche formation and metastasis. Depletion of TAMs disrupted lung pre-metastatic niches and thereby prevented metastasis. Treatment with the CM from CYP4A10^high M2 macrophages (M2) increased pre-metastatic niche formation and metastatic burden in the lungs, whereas CYP4A inhibition attenuated these effects. In vitro TAM polarization away from the M2 phenotype induced by CYP4A inhibition decreased VEGFR1⁺ myeloid cell migration and fibronectin expression, accompanied with downregulation of STAT3 signaling. Conversely, overexpression of CYP4A or exogenous addition of 20-hydroxyeicosatetraenoic acid promoted M2 polarization and cytokine production of macrophages and thereby enhanced migration of VEGFR1⁺ myeloid cells, which were reversed by siRNA or pharmacological inhibition of STAT3. Importantly, a combined blocking M2 macrophage-derived factors TGF-β, VEGF and SDF-1 abolished VEGFR1⁺ myeloid cell migration and fibroblast activation induced by CYP4A. In summary, CYP4A in TAMs is crucial for lung pre-metastatic niche formation and metastasis, and may serve as a potential therapeutic target in human cancer.

Cloning and expression pattern of chicken Pitx2: a new component in the SHH signaling pathway controlling embryonic heart looping

Asymmetry along the left-right axis of the embryo is a vital feature of vertebrate embryogenesis. In this study, we report the isolation and characterization of a bicoid-related homeobox gene, cPitx2, which displays left-right asymmetric expression during early chick embryogenesis. Asymmetric expression of cPitx2 is first detected at stage 7 and is restricted to mesodermal tissues on the left side of the embryo including the left sided lateral mesoderm, the left sided precardiac mesoderm, and the left half epimyocardium of the primitive heart. cPitx2 is also detected in the presumptive blood islands and endothelia of the embryonic blood vessels. Implantation of Sonic hedgehog (SHH) protein soaked beads on the right side of embryos induced ectopic cPitx2 expression on that side. Based on these observations, we suggest that cPitx2 is a component in SHH signaling pathway and plays a role in determining left-right asymmetry and in vasculogenesis during avian embryogenesis.

Minimum length of sequence homology required for in vivo cloning by homologous recombination in yeast

With efficient homologous recombination in Saccharomyces cerevisiae, a rapid in vivo cloning technique has been available. Here we demonstrated that 30 bp of a homologous sequence at each end of a DNA fragment is sufficient to integrate the fragment into a linearized plasmid in yeast. To obtain a high yield of recombination transformants, however, more than 60 bp are desirable. Interestingly, we observed that 20 bp of homology at one end of a DNA fragment is sufficient for efficient recombination provided that the other end contains 80 bp of homologous sequence. Some applications, including high-throughput transferring of EST inserts to the yeast expression systems for the Human Genome Project, are discussed.

A novel lncRNA, LUADT1, promotes lung adenocarcinoma proliferation via the epigenetic suppression of p27

Long noncoding RNAs (lncRNAs) are known to regulate the development and progression of various cancers. However, few lncRNAs have been well characterized in lung adenocarcinoma (LUAD). Here, we identified the expression profile of lncRNAs and protein-coding genes via microarrays analysis of paired LUAD tissues and adjacent non-tumor tissues from five female non-smokes with LUAD. A total of 498 lncRNAs and 1691 protein-coding genes were differentially expressed between LUAD tissues and paired adjacent normal tissues. A novel lncRNA, LUAD transcript 1 (LUADT1), which is highly expressed in LUAD and correlates with T stage, was characterized. Both in vitro and in vivo data showed that LUADT1 knockdown significantly inhibited proliferation of LUAD cells and induced cell cycle arrest at the G0–G1 phase. Further analysis indicated that LUADT1 may regulate cell cycle progression by epigenetically inhibiting the expression of p27. RNA immunoprecipitation and chromatin immunoprecipitation assays confirmed that LUADT1 binds to SUZ12, a core component of polycomb repressive complex 2, and mediates the trimethylation of H3K27 at the promoter region of p27. The negative correlation between LUADT1 and p27 expression was confirmed in LUAD tissue samples. These data suggested that a set of lncRNAs and protein-coding genes were differentially expressed in LUAD. LUADT1 is an oncogenic lncRNA that regulates LUAD progression, suggesting that dysregulated lncRNAs may serve as key regulatory factors in LUAD progression.

Current progress in black phosphorus materials and their applications in electrochemical energy storage

Recently, a new two-dimensional material, single- or few-layered black phosphorus (BP), has attracted considerable attention for applications in electronics, optoelectronics, and batteries due to its unique properties, including large specific surface area, anisotropy, and tunable and direct band gaps. In particular, contributions to electrochemical energy storage devices, such as lithium and sodium ion batteries and supercapacitors, have emerged. However, critical issues remain to be explored before scaled-up commercial production of BP, such as preparation, stability, and performance. Herein, we present the first review of recent progress in BP-based electrochemical energy storage device. The preparation and electrochemical properties of black phosphorus, recent advances, potential challenges, and relevant perspectives in electrochemical energy storage, and the potential of BP are discussed in this work.

Mutation of the Emx-1 homeobox gene disrupts the corpus callosum

Expression of the Emx-1 homeobox gene is largely restricted to the developing and mature cerebral cortex. To study its function, two lines of mice were generated using gene targeting methods that have a deletion that includes the N-terminal coding region of Emx-1. Mice homozygous for the deletion were viable and fertile and exhibited no obvious behavioral defects. However, 100% of homozygous mice lack most or all of their corpus callosum, the principle fiber tract that connects the left and right cerebral hemispheres. Heterozygotes show partial penetrance for the corpus callosum abnormality. The histology and various molecular properties of the cerebral cortex appear normal in the mutant mice.

Characterization of pu-erh tea using chemical and metabolic profiling approaches

In this study, the chemical constituents of pu-erh tea, black tea, and green tea, as well as those of pu-erh tea products of different ages, were analyzed and compared using a chemical profiling approach. Differences in tea processing resulted in differences in the chemical constituents and the color of tea infusions. Human biological responses to pu-erh tea ingestion were also studied by using ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOFMS) in conjunction with multivariate statistical techniques. Metabolic alterations during and after pu-erh tea ingestion were characterized by increased urinary excretion of 5-hydroxytryptophan, inositol, and 4-methoxyphenylacetic acid, along with reduced excretion of 3-chlorotyrosine and creatinine. This study highlights the potential for metabonomic technology to assess nutritional interventions and is an important step toward a full understanding of pu-erh tea and its influence on human metabolism.

Msx1 is required for the induction of Patched by Sonic hedgehog in the mammalian tooth germ

We have used the mouse developing tooth germ as a model system to explore the transmission of Sonic hedgehog (Shh) signal in the induction of Patched (Ptc). In the early developing molar tooth germ, Shh is expressed in the dental epithelium, and the transcripts of Shh downstream target genes Ptc and Gli1 are expressed in dental epithelium as well as adjacent mesenchymal tissue. The homeobox gene Msx1 is also expressed in the dental mesenchyme of the molar tooth germ at this time. We show here that the expression of Ptc, but not Gli1, was downregulated in the dental mesenchyme of Msx1 mutants. In wild-type E11.0 molar tooth mesenchyme SHH-soaked beads induced the expression of Ptc and Gli1. However, in Msx1 mutant dental mesenchyme SHH-soaked beads were able to induce Gli1 but failed to induce Ptc expression, indicating a requirement for Msx1 in the induction of Ptc by SHH. Moreover, we show that another signaling molecule, BMP4, was able to induce Ptc expression in wild-type dental mesenchyme, but induced a distinct expression pattern of Ptc in the Msx1 mutant molar mesenchyme. We conclude that in the context of the tooth germ Msx1 is a component of the Shh signaling pathway that leads to Ptc induction. Our results also suggest that the precise pattern of Ptc expression in the prospective tooth-forming region is controlled and coordinated by at least two inductive signaling pathways.

Pharmacometabonomic Phenotyping Reveals Different Responses to Xenobiotic Intervention in Rats

In conventional pharmacological studies, intersubject differences within an animal strain are normally neglected, leading to variations in pharmacological outcomes in response to the same stimulus. Using two classical experimental models, the Streptozotocin (STZ)-induced diabetic model of Wistar rats and the high-energy, diet-induced obesity model of Sprague-Dawley rats, we demonstrate that the different outcomes of STZ or diet intervention are closely associated with variation in predose (baseline) urinary metabolic profiles of the rats. The pharmacometabonomic analysis of predose metabolic profiles indicates that the intersubject difference is, to a great extent, associated with gut-microbiota, which predisposes different pathophysiological outcomes upon diet alteration or chemical stimulus. We hypothesize that there may exist an important association between observations from these two models and the obese/diabetic human population in that subtle variations in metabolic phenotype may predetermine different systems' responses to xenobiotic perturbation, ultimately leading to varied pathophysiological processes. Results from two independent models also suggest that the pharmacometabonomics approach is of great importance in the study of pharmacology and clinical drug evaluations, where endogenous metabolite signatures of predose individuals should be taken into consideration to minimize intersubject difference and the resulting variation in the postdose pharmacological outcomes.

Sequence, organization, and transcription of the Dlx-1 and Dlx-2 locus

There are at least five murine Dlx genes that are related to the Drosophila Distal-less homeobox gene. The Dlx genes are primarily expressed in the developing forebrain, derivatives of the cranial neural crest and restricted epidermal craniofacial and limb domains. Dlx-2 is required for differentiation of subsets of cranial neural crest and forebrain cells. Previous genomic studies have shown that Dlx-1 and Dlx-2 are linked on mouse chromosome 2, near the HoxD cluster. Here we report a detailed analysis of the nucleotide sequence (approximately 14 kb), organization, and transcription of the murine Dlx-1 and Dlx-2 locus. In addition, we show that Dlx-1 makes multiple sense transcripts and at least one antisense transcript, whereas Dlx-2 makes one major transcript. The sequence of the human Dlx-2 gene is reported and is compared to that of the murine gene. Finally, sequence analysis of the deduced protein sequences reveals several candidate functional domains.

Selective expression of Nkx-2.2 transcription factor in chicken oligodendrocyte progenitors and implications for the embryonic origin of oligodendrocytes

Recent studies have demonstrated that oligodendrocytes originate from the ventral region of the developing spinal cord. However, the precise neuroepithelial origin of oligodendrocytes remains controversial, and the transcriptional control of oligodendrocyte lineage specification is largely unknown. Here we present evidence that oligodendrocytes in the embryonic chicken spinal cord can be generated from neuroepithelial cells that express the Nkx-2.2 homeodomain transcription factor. Nkx-2.2 expression is initially confined to a narrow stripe of neuroepithelium flanking the floor plate. Later, Nkx-2.2+ cells migrate ventrally and dorsolaterally into the surrounding gray and white matter regions where they undergo rapid proliferation. Double labeling experiments revealed that Nkx-2.2+ cells coexpress markers specific for oligodendrocyte progenitors, e.g., PDGFRalpha+, O4, and R-mAb antigens. In the brain, the Nkx-2.2 cells are also highly migratory and can generate oligodendrocytes. The persistent expression of the Nkx-2.2 homeodomain transcription factor in the oligodendrocyte lineage suggests its important role in the control of oligodendrocyte development.

Protective effect of flavonoids from Scutellaria baicalensis Georgi on cerebral ischemia injury

The protective effect of flavonoids extracted from Scutellaria baicalensis Georgi on cerebral ischemia injury has been explored in experimental animals. Scutellaria flavonoid (SF) could significantly prolong gasping time (prolonged ratio, 23.79%) and survival time after carotid artery occlusion, and decrease attenuate malondialdehyde (MDA) content in damaged brain tissues from 118.56+/-47.95 nmol/g in untreated to 199.29+/-24.24 nmol/g. SF could also increase the content of superoxide dismutase (SOD) in brain tissues after ischemic mice from 1486+/-94 NU/g in untreated to 1168+/-76 NU/g, and showed significant protective effect on cerebral hypoxia and reperfusion brain tissues in middle cerebral artery occlusion (MCAO) procedure. Additionally, SF has inhibitory effect on platelet aggregation, with the average inhibition rate of 45.52%, while the aspirin group was 54.96%. These results suggest that SF has a significant protective effect on cerebral ischemia and ischemia-reperfusion induced brain injury.

Electronic structure and magnetic properties of penta-graphene nanoribbons

Calculations predict that bipolar magnetic semiconductor and half-metal behaviors can be observed in penta-graphene nanoribbons.

Leukocyte-specific adaptor protein Grap2 interacts with hematopoietic progenitor kinase 1 (HPK1) to activate JNK signaling pathway in T lymphocytes

Immune cell-specific adaptor proteins create various combinations of multiprotein complexes and integrate signals from cell surface receptors to the nucleus, modulating the specificity and selectivity of intracellular signal transduction. Grap2 is a newly identified adaptor protein specifically expressed in lymphoid tissues. This protein shares 40--50% sequence homology in the SH3 and the SH2 domain with Grb2 and Grap. However, the Grap2 protein has a unique 120-amino acid glutamine- and proline-rich domain between the SH2 and C-terminal SH3 domains. The expression of Grap2 is highly restricted to lymphoid organs and T lymphocytes. In order to understand the role of this specific adaptor protein in immune cell signaling and activation, we searched for the Grap2 interacting protein in T lymphocytes. We found that Grap2 interacted with the hematopoietic progenitor kinase 1 (HPK1) in vitro and in Jurkat T cells. The interaction was mediated by the carboxyl-terminal SH3 domain of Grap2 with the second proline-rich motif of HPK1. Coexpression of Grap2 with HPK1 not only increased the kinase activity of HPK1 in the cell, but also had an additive effect on HPK1 mediated JNK activation. Furthermore, over expression of Grap2 and HPK1 induced significant transcriptional activation of c-Jun in the JNK signaling pathway and IL-2 gene reporter activity in stimulated Jurkat T cells. Therefore, our data suggest that the hematopoietic specific proteins Grap2 and HPK1 form a signaling complex to mediate the c-Jun NH(2)-terminal kinase (JNK) signaling pathway in T cells.

Determination of sphinganine, sphingosine and Sa/So ratio in urine of humans exposed to dietary fumonisin B1

Fumonisin B1 (FB1) is an inhibitor of sphinganine N-acyltransferase and the increase in the sphinganine/ sphingosine (Sa/So) ratio in urine or serum has been proposed as a biomarker to evaluate exposure to fumonisins. The objectives of this study were to (1) develop a liquid chromatographic method sufficiently sensitive to determine the low concentration of free Sa in male human urine, and (2) analyse So and Sa in human urine and monitor the Sa/So ratio in urine of humans exposed to FB1 in corn diets over 1 month. The liquid chromatographic method involved isolation from human urine of exfoliated cells followed by an extraction of free sphingoid bases and their separation and quantification by high performance liquid chromatography. The detection limits for So and Sa were 0.15 ng/ml in female urine (2 ml used) and 0.005 ng/ ml in male urine (60 ml used). Twenty-eight healthy adult volunteers consumed for 1 month a normal diet containing their homegrown corn potentially contaminated with FB1. Immediately preceding the start of the test, morning urine samples for the determination of So and Sa were collected from each person, and the corn samples used in cooking were obtained from each family for the determination of FB1. At the end of the test period, morning-urine samples were collected from each person and analysed again. The daily FB1 intakes were estimated and used to assess the relationship between them and the urinary Sa/So ratios in humans exposed to dietary FB1 over 1 month. All the homegrown corn samples contained FB1 ranging from 0.08 to 41.1 mg/kg, and the estimated daily FB1 intakes ranged from 0.4 to 740 microg/kg b.w./day. The 1-month monitoring results suggest that sphingolipid metabolism of humans could be affected by FB1 intake, the urinary Sa/So ratio may be useful for evaluating FB1 exposure when the contamination of FB1 is high, and that males are more sensitive to FB1 disruption of sphingolipid metabolism than females.